Wetlands

Methane Cycling Contributes to Distinct Patterns in Carbon Stable Isotopes of Wetland Detritus Abstract Increasing global temperatures are changing the balance between carbon sequestration and its microbial processing in wetlands, making the tracking of these processes important. We used detrital carbon stable isotopes (δ13C) to trace aerobic decomposition and CH4 production in two experiments conducted in Alaskan wetlands. In laboratory bottle incubations, larger decreases in detritus δ13C corresponded to higher net CH4 and CO2production rates. Because net CH4 production was the stronger predictor and its effect was negative, we hypothesize that decreases in δ13C trace concurrent CH4 production and oxidation. In a field experiment, decreases in detritus δ13C were not correlated with aerobic decomposition rates, but were positively correlated with CH4 production potentials as estimated from bottle incubations. We hypothesize that the positive relationship reflects only CH4 production, rather than concurrent production and oxidation. Although CH4 production rates were correlated with changes in detrital δ13C in both experiments, the direction of this relationship differed between laboratory and field with important consequences for the scale of ecological experiments. Our study demonstrates that CH4 cycling can create distinct patterns in δ13C of wetland detritus. Future studies should conduct explicit mass balance experiments to clarify mechanisms and determine the importance of scale in shaping isotopic patterns.

Paleoecological assessment of cladoceran community dynamics in two subarctic peatlands Abstract Crustacean community structure and dynamics are very well studied in lakes, rivers and oceanic systems but wetlands, where moisture conditions fluctuate, have not received equal attention in research. For example, cladoceran communities in peatland systems in the subarctic region have not been fully investigated. We used paleolimnological and paleoecological methods to study plant and cladoceran assemblages and the community dynamics in two subarctic peatlands, which differ in their hydrological characteristics. At the first site, Iitto, river floods introduce planktonic species to fen pools and the steep topography of the catchment induces rapid but relatively short flooding periods. Fluctuating environmental conditions result in a high amount of cladoceran resting stages in the samples. At the other site, Kaamanen, the cladoceran assemblage goes through clear directional changes, which could be attributed to changes in fen hydrology and ultimately to climatic changes during the past two millennia.

Rising Tides: Assessing Habitat Vulnerability for an Endangered Salt Marsh-Dependent Species with Sea-Level Rise Abstract Salt marsh-dependent species are vulnerable to impacts of sea-level rise (SLR). Site-specific differences in ecogeomorphic processes result in different SLR vulnerabilities. SLR impacts to Ridgway’s rail (Rallus obsoletus) of Southern California (SC) and San Francisco Bay (SF), U.S.A. could foreshadow SLR effects on other coastal endemic species. Salt marsh vulnerabilities to SLR were forecasted across 14 study sites using the Wetland Accretion Rate Model of Ecosystem Resilience, which accounts for changes in above and belowground marsh processes. Changes in suitable habitat for rail were projected with MaxEnt. Under a high (166 cm/100 yr) SLR scenario, current extent of suitable habitat is projected to increase by 34% across the combined area of 14 sites by 2050, but by 2100, total habitat suitability is projected to decrease by 83%, with six salt marshes losing over 95% of suitable habitat. Under a high SLR scenario, SF’s suitable habitat is predicted to increase by 35% at mid-century, and SC’s current suitable habitat extent will increase by 24%. However, by 2100, SF is forecasted to lose 84% of suitable habitat and SC to lose 80% of its current habitat extent. If accretion rates cannot keep pace with SLR, salt marsh obligate species are in danger of being extirpated from their habitat.

Rapid Increases in Bat Activity and Diversity after Wetland Construction in an Urban Ecosystem Abstract Wetland construction can mitigate the biodiversity and water quality losses associated with reduced natural wetland coverage. While beneficial effects of wetland construction for bats have been observed in natural and rural settings, the effects of wetland construction on bats in an urban ecosystem are less understood. We used passive acoustic monitoring to measure bat activity levels and diversity at two constructed wetlands and two control sites on the University of North Carolina Greensboro campus, in Greensboro, North Carolina, USA. We monitored all 4 sites before and after wetland construction. Pre-wetland construction, there were few differences in bat activity and community structure at our sites. After wetland construction, we observed greater activity, attributable to all species we recorded, at wetland sites compared to control sites. Species diversity and species richness were also higher at wetland sites compared to control sites. When comparing the same sites before and after wetland construction, both bat activity and species richness increased after construction, but the effects were seen in Winter and not Spring. Our results demonstrate that bats use constructed wetlands in urban ecosystems similarly to other habitat settings. Increases in bat activity, diversity, and species richness occurred within one year of wetland construction.

Landscape Indicators and Ecological Condition for Mapped Wetlands in Pennsylvania, USA Abstract Although landscape indicators are widely used to assess wetland ecological condition, how they capture the spatial arrangement of land cover is not well addressed. We conducted a Level 1 Landscape Assessment to revise strengths and weaknesses of landscape indicators when links to ecological conditions are strong. Wetland sites mapped by the National Wetlands Inventory were defined as 1-km radius circles around centroid points. Forest fragmentation type, road density, Landscape Development Intensity (LDI) index, and percentage of impervious surface were quantified at each site by integrating land cover and road network information. Based on forest cover, 6% of wetland sites scored in the highest ecological category while 45% fit into the lowest one. Results showed high dispersion of data for the impervious surface indicator in the lowest condition category. When comparing LDI and impervious surface under different landscape compositions and configurations, LDI better described disturbance in agricultural areas where road density was low. Impervious surface better reflected the occurrence of fragmented landscapes at forested areas with high percentage of edge forest cover. In addition, a significant proportion of freshwater wetlands (60%) in the lowest condition category was associated with first-order streams, indicating a wide range of disturbance at some headwater watersheds.

Mathematical Formulations for Three Components of Hydroperiod in Tidal Wetlands Abstract Hydroperiod has numerous ecological function and effective methods for calculating hydroperiod would be valuable for different ecological or biological studies. However, accurate computation of hydroperiod remain challenging mainly due to absence of accurate mathematical formulation. Additionally, computing hydroperiod is complex due to the daily fluctuating water levels from tides, wind, river flows, and other meteorological events. This research presents quantitative formulations for three components of hydroperiod (flooding depth, frequency, and duration) directly from the physical dynamics of water surface movement in a tidal wetland. A set of National Oceanic and Atmospheric Administration (NOAA) tide gauges along the U.S. West, East, and Gulf coasts are selected to demonstrate the application of the new formulations. The computational results in terms of duration are compared with Morris non-dimensional depth (D) of hydroperiod. The comparison indicates that D is a linear-triangular approximation of sinusoid tide curve and it would generally be a good estimate of the duration component of hydroperiod within the tidal range and the accuracy of D depends on geographic location of the stations that determine the tidal regimes. Whereas the proposed formulation is not limited to variations in tide regimes and can be used as a powerful tool to determine hydroperiod.

Quantifying Functional Increases Across a Large-Scale Wetland Restoration Chronosequence Abstract Over 300,000 ha of forested wetlands have undergone restoration within the Mississippi Alluvial Valley region. Restored forest successional stage varies, providing opportunities to document wetland functional increases across a large scale restoration chronosequence using the Hydrogeomorphic (HGM) approach. Results from >600 restored study sites spanning a 25 year chronosequence indicate that: 1) wetland functional assessment variables increased toward reference conditions; 2) restored wetlands generally follow expected recovery trajectories; and 3) wetland functions display significant improvements across the restoration chronosequence. A functional lag between restored areas and mature reference wetlands persists in most instances. However, a subset of restored sites have attained mature reference wetland conditions in areas approaching or exceeding tree diameter and canopy closure thresholds. Study results highlight the importance of site selection and the benefits of evaluating a suite of wetland functions in order to identify appropriate restoration success milestones and design monitoring programs. For example wetland functions associated with detention of precipitation (a largely physical process) rapidly increased under post restoration conditions, while improvements in wetland habitat functions (associated with forest establishment and maturation) required additional time. As the wetland science community transitions towards larger scale restoration efforts, effectively quantifying restoration functional improvements will become increasingly important.

Microtopography Alters Hydrology, Phenol Oxidase Activity and Nutrient Availability in Organic Soils of a Coastal Freshwater Forested Wetland Abstract Hummock-hollow microtopography is a unique feature of wetland ecosystems, but our understanding of its effects on soil carbon and nutrient cycling is limited. We investigated effects of microtopography on hydrology, phenol oxidase activity (POX) and nutrient availability in a freshwater forested wetland of coastal North Carolina. Water table depth (WTD) was measured from September 2012 to August 2013. Ion exchange probes were used to measure nutrient concentrations prior to soil sample collection in August 2013. WTD fluctuated seasonally with maximum and minimum WTD resulting in 92% (September 2012) to 8% (June 2013) of the site in flooded and non-flooded conditions, respectively. Hummocks had greater POX activity (12 ± 2.8 μmol g−1 h−1) compared to hollows (4 ± 0.7 μmol g−1 h−1) and greater concentrations of potassium and sulfur, but lower concentrations of calcium, iron, zinc, boron, and lead. POX was negatively correlated with soil water content. Higher enzyme activity in hummocks likely drives greater rates of carbon and nutrient cycling compared to hollows, consistent with observations that hummocks are hotspots for CO2 fluxes. Microtopography altered site-level hydrologic conditions, phenol oxidase activity and nutrient availability with important implications for understanding carbon and nutrient cycling in forested wetlands and response to changes in hydrology.

Morphology of Drained Upland Depressions on the Des Moines Lobe of Iowa Abstract An algorithm developed to derive the morphology of depressional landscape features was applied to the Iowa portion of the Des Moines Lobe using high-resolution hydrologically corrected digital elevation models. In total, 173,171 topographically intact, drained upland depressions were identified, and their individual morphologies determined. The frequency distributions of maximum area of inundation, maximum depth, and maximum storage volume of depressions were described by a power-law function. Maximum storage volume was strongly related to maximum inundation area through a power-law model, the parameters of which differ from those reported for other areas of the North American Prairie Pothole Region. The spatial distributions, densities, and bulk morphological attributes of upland depressions within the DML-IA tend to be coincident with the region's distinctive glaciated sub-regions.

Effects of Nutrient-Limitation on Disturbance Recovery in Experimental Mangrove Wetlands Abstract Coastal wetlands are exposed to high-energy storms that influence plant and soil structure. To understand how nutrient availability interacts with storm-induced plant stress, we tested how defoliation interacts with nutrient enrichment to affect carbon (C) and nutrient (nitrogen, N; phosphorus, P) cycling and storage within soils and plants. In outdoor experimental mesocosms, we defoliated red mangrove saplings (Rhizophora mangle), added 30 g of inorganic P to peat soils, and quantified plant [elemental stoichiometry (C:N, C:P, N:P), leaf count, and above- and below- ground biomass] and soil responses [C:N, C:P, N:P, litter breakdown rate (k), soil CO2 efflux] during a 42-d recovery period. Mangroves rapidly regrew all removed leaves and recovered nearly 30% of leaf biomass. Mangrove biomass %P increased by 50% with added P; however, soil stoichiometry remained unchanged. Defoliation reduced Soil CO2 efflux by 40% and root litter k by 30%. Phosphorus was quickly incorporated into mangrove biomass and stimulated nighttime soil CO2 efflux. This work highlights the importance of testing interactions of nutrient availability and plant stress on plant and soil biogeochemical cycling and suggests that plants quickly incorporate available nutrients into biomass and defoliation can lead to reduced soil C losses.

Environmental Science and Pollution Research

MnO 2 -loaded microorganism-derived carbon for U(VI) adsorption from aqueous solution Abstract A low-cost industrial microorganism, Saccharomyces cerevisiae, was employed as a precursor to synthesize carbon/MnO2 composites (MMCs) via an oxidation-reduction reaction and one-step carbonization method for U(VI) adsorption. Scanning electron microscopy and nitrogen adsorption measurement indicated that the microorganism’s carbonization could form surface porous structure and increase the specific surface area. Batch experiments showed that the maximum U(VI) adsorption capacity of MMCs reached 207 mg g−1 at [U(VI)]initial = 25 mg L−1 and pHinitial = 4.5. The obtained thermodynamic and kinetic parameters suggested that the process is endothermic, spontaneous, and chemisorption. FTIR and X-ray photoelectron spectroscopy demonstrated that the surface hydroxyl groups of composites might be the reactive adsorption sites for U(VI). Additionally, 0.5 mol L−1 HNO3 solution could desorb ~ 95% uranium from U(VI)-loaded MMCs, and materials exhibited good regenerated availability. This study suggests that MMCs can be a potential adsorbent for U(VI) preconcentration and removal from radioactive wastewater.

Curcumin and quercetin synergistically attenuate subacute diazinon-induced inflammation and oxidative neurohepatic damage, and acetylcholinesterase inhibition in albino rats Abstract The ubiquitous use of diazinon (DZN, an organophosphorus insecticide) has increased the probability of occupational, public, and the ecosystem exposure; these exposures are linked to negative health outcomes. The flavonoids curcumin (CUR) and quercetin (QUE) exert significant anti-inflammatory and antioxidant activities against toxicants, including insecticides. However, it is unclear whether their combination enhances these activities. Therefore, 40 albino rat were divided randomly into the CTR, DZN, CUR + DZN, QUE + DZN, and CUR + QUE + DZN groups, which are treated daily via gavage for 28 days. DZN induced neurohepatic inflammation and oxidative damage, which was confirmed by significant (P < 0.05) induction of aspartate and alanine aminotransferases, alkaline phosphatase, lactate dehydrogenase, γ-glutamyl transferase, and tumor necrosis factor-α and inhibition of acetylcholinesterase activity. Furthermore, the liver and brain of DZN-exposed rats exhibited a notable elevation in MDA level paralleled with reduction in antioxidant molecules, i.e., glutathione, superoxide dismutase, glutathione peroxidase, and catalase. The pretreatment of DZN-intoxicated rats with CUR or QUE substantially mitigated neurohepatic dysfunction and inflammation and improved liver and brain antioxidant status with reducing oxidative stress levels. Furthermore, pretreatment with CUR + QUE synergistically restored the neurohepatic dysfunction and oxidative levels to approximately normal levels. The overall results suggested that CUR or QUE inhibits DZN-mediated neurohepatic toxicity via their favorable anti-inflammatory, antioxidant, and free radical-scavenging activities. Moreover, both QUE and CUR may be mutual adjuvant agents against oxidative stress neurohepatic damages.

Environmental efficiency of Saccharomyces cerevisiae on methane production in dairy and beef cattle via a meta-analysis Abstract The objective of the present study is to examine the effect of yeast (Saccharomyces cerevisiae) on reduction of methane (CH4) production in dairy and beef cattle using meta-analytic methods. After compilation of relevant scientific publications available from the literature between 1990 and 2016, and applying exclusion and inclusion criteria, meta-analyses of data from dairy and beef cattle were applied for the pooled dataset or for each animal category (dairy or beef). The results of meta-analysis of all three datasets (all cattle, dairy cattle, or beef cattle) suggested that effect size of yeast either on daily CH4 production or on CH4 production per dry matter intake (CH4/DMI) was not significant. The results of Q test and I2 statistic suggest that there is no heterogeneity between different studies on CH4 production and CH4/DMI. The results of meta-analysis suggest that use of yeast (Saccharomyces cerevisiae) as feed additive does not offer significant results in terms of reduction of CH4 production in dairy and beef cattle. Further research on the effects of different doses of yeast, use of yeast products, different strains, and experimental designs is warranted to elucidate the effects of yeasts on methane production in the rumen.

Synthesis of graphene by in situ catalytic chemical vapor deposition of reed as a carbon source for VOC adsorption Abstract Few-layer graphene was synthesized by in situ catalytic carbon vapor deposition (CCVD) method, using reed as a carbon source and Ni, Cu, and Mg salts as the catalyst compounds. The synthesized graphene was also used for adsorption of VOCs. Furthermore, the effect of organic additives, sorbitol, and citric acid on catalyst compounds was investigated by temperature-programmed reduction analysis (H2-TPR). The products’ properties were characterized by thermo-gravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) surface area analysis. TEM and FE-SEM images confirmed the formation of graphene sheets. Activation of the graphene by phosphoric acid at 500 °C and then by CO2 at 800 °C increased the surface area from 298 to 568 m2/g. Gasoline working capacity of the activated graphene was 65.24 g/ladsorbent. Graphical abstract Few-layer graphene was synthesized by in situ catalytic carbon vapor deposition (CCVD) method using reed as a carbon source and Ni, Cu, and Mg salts as the catalyst compounds and used for adsorption of VOCs.

Distribution and potential ecological risk assessment of trace elements in the stream water and sediments from Lanmuchang area, southwest Guizhou, China Abstract Trace elements contamination in sediment is regarded as the global crisis with a large share in developing countries like China. Water and sediment samples were collected during (2016) from Qingshui Stream and analyzed for major physicochemical properties and trace elements by using ICP-MS. Our result of sediments showed that studied trace elements (except Pb, Cd, Co) had a concentration higher than Chinese sediment guideline as well as stream water data for studied trace elements (except Cr, Pb, Cd, Cu, and Zn) had a higher concentration than the maximum permissible safe limit of WHO. Contamination factor (CF) confirmed a moderate to high contamination in the sediment samples due to As and Tl, respectively. The values of pollution load index (PLI) were found above one (> 1), describing the progressive sediment quality decline. Pearson correlation showed that there was a significant positive association between Tl and As (r = 0.725, p < 0.05) in sediment samples. Results revealed that water-rock interaction, weathering of Tl sulfide mineralization, and hydrogeological conditions were major sources of stream water and sediments contamination in the study area. This experimental study contributes to a better understanding of the geochemistry and prevention of trace element contamination in sediments from Lanmuchang area.

How does natural resource dependence affect public education spending? Abstract The “resource curse” phenomenon has been the subject of extensive research, with its causes and transmission mechanisms primarily examined from the perspectives of economic development and rent seeking. Education is a major factor contributing to economically sustainable development, owing to its potential for improving cognition and skill levels and thereby enhancing worker productivity. The crowding-out or crowding-in effect of natural resource dependence on public education spending has been identified as one of the key mechanisms of the resource curse or blessing. Using panel data from 31 Chinese provinces, this empirical study revealed a positive correlation between natural resource dependence and public education expenditure, demonstrating the impact of the crowding-in effect, exerted by natural resource dependence, on public education expenditure. Abundant natural resources can provide funds for education expenditure. The sample was further divided into eastern and central and western regions. The results indicate that the crowding-out effect of natural resource dependence only affects public education expenditure in the Eastern region, while the crowding-in effect of natural resource dependence on public education expenditure in the central and western regions. Research shows that the regional differences of crowding-out or crowding-in effect are very obvious, so the government should adopt transfer payment to promote balanced regional development. Better economic and social policies will help to translate wealth from natural resources into economic growth. Thus, a “resource blessing” may emerge to replace the “resource curse.” Fairly distributed and higher quality education will enhance human capital, thereby promoting economic growth from its current resource-driven pattern to a knowledge-driven pattern.

Enhanced nitrogen removal in biochar-added surface flow constructed wetlands: dealing with seasonal variation in the north China Abstract In the present study, the performance of surface flow constructed wetlands (SFCWs) added with different dosage of biochar (group A 0%, group B 10%, group C 20%; v/v) was investigated, to evaluate the effect of biochar on nitrogen removal of a constructed wetland. No significant difference was observed in NH4+-N removal among three groups even during different seasons. Labile organic carbon released from biochar distinctly enhanced denitrification process, which improved NO3−-N removal efficiency by 4.58% in group B and 10.33% in group C. More importantly, compared with group A, biochar addition increased plant N removal by 82.24% and 192.11% in groups B and C, respectively. This result indicated that biochar could increase the accumulation of plant net biomass. In addition, TN removal of group A was much lower at low temperature (4.9 °C). However, no obvious influence of temperature on TN removal was observed in groups B and C with biochar addition. Microbial community analysis showed that, compared with that in group A, the total relative abundance of the main denitrification bacteria (Proteobacteria, Firmicutes, and Bacteroidetes) increased by 0.81% in group B and 13.63% in group C. These results provide a reasonable strategy for improving the performance of SFCWs under cold climate.

Composts as alternative to inorganic fertilization for cereal crops Abstract The use of treated organic products as fertilizers and soil amendments not only results in economic benefits for the small-scale farmer, but it also reduces pollution due to reduced nutrient run-off and N leaching. In this work, the feasibility of using composts as fertilizers and soil improvers has been evaluated at the field level, in barley and soft wheat crops (two successive cultivations of each crop). The applied treatments consisted of two commercial composts (compost manure and sewage sludge compost) added to the soil either alone (T1 and T3) or in combination with inorganic fertilizers (T2 and T4) and a conventional mineral fertilization (T5). Physical, physical-chemical, chemical, microbiological, and biochemical parameters were determined in the soil after each harvest. In both barley and wheat crops, soils treated with composts showed higher organic C, humic substances, and humic acid contents than the inorganically fertilized soil, as well as higher contents of water-soluble P, K, Ca, Mg, and S. In both successive crops, all treatments led to similar yields of total barley and wheat vegetal material (straw + ears) and grain, differences between treatments being not statistically significant (p ≤ 0.05). Organically treated soils showed higher microbial size and activity than inorganically treated soils as well as higher water-holding capacity. It can be concluded that quality organic composts can be used, at suitable rates, alone or in combination with inorganic fertilizers, as a good alternative to inorganic fertilization for cereal cultivation, improving soil characteristics while giving similar yield and crop quality than conventional inorganic fertilization.

Contrastive removal of oxytetracycline and chlortetracycline from aqueous solution on Al-MOF/GO granules Abstract The presence of tetracycline antibiotics (TCS) in the water and wastewater has raised growing concern due to its potential environmental impacts; thus, their removal is of high importance. In this study, a novel aluminum-based MOF/graphite oxide (Al-MOF/GO) granule was prepared as an adsorbent for the removal of TCS including oxytetracycline (OTC) and chlortetracycline (CTC). The adsorbent was characterized via XRD, FTIR, BET, SEM, and XPS methods. The granules exhibited similar crystal structure and some new mesopores appearing compared to the parent Al-MOF/GO powder. In addition, the adsorption behavior of OTC and CTC on samples was explored as a function of initial concentration, contact time, pH, and ionic strength by means of batch experiments. The adsorption capacity reached to 224.60 and 240.13 mg·L−1 for OTC and CTC, at C0 = 60 mg·L−1as well as ambient temperature respectively. Moreover, the adsorption process of OTC and CTC on Al-MOF/GO samples can be better delineated by pseudo-second-order kinetics and Freundlich isotherm models. Besides, the adsorption mechanism over Al-MOF/GO granules was proposed, which could be ascribed to π-π interaction, cation-π bonding, and hydrogen bond. Finally, the great water stability, separation performance, and regeneration efficiency of these novel granules indicated their potential application in the OTC and CTC removals from aqueous solution.

Bisphenol S exposure affects gene expression related to intestinal glucose absorption and glucose metabolism in mice Abstract Bisphenol S, an industrial chemical, has raised concerns for both human and ecosystem health. Yet, health hazards posed by bisphenol S (BPS) exposure remain poorly studied. Compared to all tissues, the intestine and the liver are among the most affected by environmental endocrine disruptors. The aim of this study was to investigate the molecular effect of BPS on gene expression implicated in the control of glucose metabolism in the intestine (apelin and its receptor APJ, SGLT1, GLUT2) and in the liver (glycogenolysis and/or gluconeogenesis key enzymes (glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK)) and pro-inflammatory cytokine expression (TNF-α and IL-1β)). BPS at 25, 50, and 100 μg/kg was administered to mice in water drink for 10 weeks. In the duodenum, BPS exposure reduces significantly mRNA expression of sodium glucose transporter 1 (SGLT1), glucose transporter 2 (GLUT2), apelin, and APJ mRNA. In the liver, BPS exposure increases the expression of G6Pase and PEPCK, but does not affect pro-inflammatory markers. These data suggest that alteration of apelinergic system and glucose transporters expression could contribute to a disruption of intestinal glucose absorption, and that BPS stimulates glycogenolysis and/or gluconeogenesis in the liver. Collectively, we reveal that BPS heightens the risk of metabolic syndrome.

Estuaries and Coasts

Response and Recovery of Low-Salinity Marsh Plant Communities to Presses and Pulses of Elevated Salinity Abstract In estuaries, future variation in sea level and river discharge will lead to saline intrusion into low-salinity tidal marshes. To investigate the processes that control the differential response and recovery of tidal freshwater marsh plant communities to saline pulses, a 3 × 5 factorial greenhouse experiment was conducted to examine the effects of a range of salinity levels (3, 5, and 10 practical salinity units (PSU)) and pulse durations (5, 10, 15, 20, and 30 days per month) on community composition of tidal freshwater marsh vegetation. Recovery of perturbed communities was also examined after 10 months. The results showed that community composition was increasingly affected by the more-saline and longer-duration treatments. The increasing suppression of salt-sensitive species resulted in species reordering, decreased species richness, and decreased aboveground biomass. Most of the plant species were able to recover from low-salinity, short-duration saline pulses in less than 1 year. However, because not all species recovered in the heavily salinized treatments, species richness at the end of the recovery period remained low for treatments that were heavily salinized during the treatment period. In contrast, plant aboveground biomass fully recovered in the heavily salinized treatments. Although the magnitude and duration of pulsed environmental changes had strong effects on community composition, shifts in community composition prevented long-term reductions in productivity. Thus, in this study system, environmental change affected species composition more strongly than it did ecosystem processes.

Ability of Eelgrass to Alter Oyster Growth and Physiology Is Spatially Limited and Offset by Increasing Predation Risk Abstract Marine foundation species have strong effects on sympatric species, but the strength may vary along environmental gradients. Climate change is shifting the distribution and magnitude of environmental gradients, making identification of when and where foundation species effects occur necessary for effective management. We reviewed existing work to identify expected mechanisms by which seagrass affect suspension feeding bivalves, then tested whether these effects shifted across estuarine conditions for two species of oysters (native Ostrea lurida and non-native Crassostrea gigas) grown in and out of eelgrass (Zostera marina) at six estuarine sites in Washington state. Hypothesized mechanisms of eelgrass influence include reduced predation pressure, reduced or altered food availability, and amelioration of environmental (pH) stress. We analyzed oyster survival, shell and tissue growth, shell strength, and stable isotope (SI) and fatty acid (FA) biomarkers. Oyster survival was > 20% lower in eelgrass at lower-estuary sites, but not up-estuary sites. Both species grew faster in eelgrass at one low-estuary (higher pH) site, but not elsewhere. Shell strength in eelgrass increased by 21.1% for native but decreased by 12.6% for non-native oysters. FA and SI biomarkers only differed in eelgrass at one site but correlated significantly to growth among individuals. No measurement showed a consistent response to eelgrass across estuarine conditions and taxa, and responses were often opposite of expectations based on published literature. These results have important implications for management and restoration of oysters in areas with eelgrass.

Nutrients in Saltmarsh Soils Are Weakly Related to those in Adjacent Coastal Waters Abstract Saltmarshes provide a broad range of high-value ecosystem services and can be sensitive to eutrophication, but elucidating such impacts at broad spatial scales demands a better understanding of the underlying nutrient linkages between saltmarsh soil and tidal waters. We used existing water quality data and field surveys of 15 saltmarshes across a broad trophic gradient of coastal waters, but similar biogeographic setting (in Ireland) to investigate if phosphorus and nitrogen pools in saltmarsh soils are related to those in tidal water across saltmarshes. We also investigated if the strength of such relationships is inversely related to ground elevation, which approximates the degree of tidal inundation. Plant-available phosphorus and nitrogen pools in soil were related to water nutrients, albeit only weakly. We did not find any support for the moderating influence of elevation, indicating that it may be obscured by internal cycling and external sources. We also found evidence for effect of birds on the saltmarsh nutrient pool. Saltmarsh soils are unlikely to serve as general sentinels of nutrient conditions in their corresponding water bodies and may need separate assessment criteria and management tools, which in turn require disentangling localised and whole-saltmarsh sources of variation in nutrient concentrations.

Correction to: Impact of Channel Deepening on Tidal and Gravitational Circulation in a Highly Engineered Estuarine Basin In the original article on page 1589, right column, second paragraph, seventh line, there is an error in the equation.

Correction to: Effects of Docks on Salt Marsh Vegetation: an Evaluation of Ecological Impacts and the Efficacy of Current Design Standards In the original article there was an error in the reported quadrat size. Sample quadrats were described as 1/16 m2 when they should have been reported as 1/32 m2 in the text of page 662.

Correction to: An Experimental Evaluation of Dock Shading Impacts on Salt Marsh Vegetation in a New England Estuary In the original article there was an error in the reported quadrat size. Sample quadrats were described as 1/16 m2 when they should have been reported as 1/32 m2 in the text of page 16 and in the figure legend for Figs. 6 and 7.

Correction to: Ecophysiology of the Olympia Oyster, Ostrea lurida , and Pacific Oyster, Crassostrea gigas In the original article there is an error on page 522 in the third paragraph of the Methods section. There is an erroneous 0 in the TWW coefficient. The corrected text is as follows.

Fish Utilization of Created vs. Natural Oyster Reefs ( Crassostrea virginica ) Abstract Once viewed as an inexhaustible fishery resource, eastern oyster reefs (Crassostrea virginica) have been dramatically depleted. In North Carolina alone, eastern oyster harvests have declined by 90% since the early 1900s. However, eastern oyster restoration and management efforts have substantially increased since the 1970s. Oyster reefs provide habitat and refuge for organisms, improve water quality, and decrease erosion. Oyster restoration projects aim to construct reefs that function similarly to their natural counterparts. Therefore, post-creation monitoring of these reefs is crucial in determining restoration success. However, monitoring is often lacking or focused only on oyster density and size rather than ecosystem functions such as nekton utilization. This study examines nekton utilization among created reefs compared to natural reefs in an estuary in Wilmington, North Carolina. The objective was to determine whether the created reefs function similarly to the natural reefs in abundance, species richness, and fish size. Using seine nets and Breder traps, reefs were sampled over a 5-month period. No significant difference was detected among reefs for nekton abundance, species richness, and standard length. This is a promising result for future management, indicating that created and natural reefs can support similar communities of fishes and shrimp.

Local Habitat and Seascape Structure Influence Seagrass Fish Assemblages in the Venice Lagoon: The Importance of Conservation at Multiple Spatial Scales Abstract Seagrass meadows are a critical component of estuarine and coastal seascapes, and their structure influences fish assemblages at multiple spatial scales. The patch mosaic model, which defines the seascape as a collection of interacting habitat types, is increasingly adopted to prioritise protected areas and design ecological restoration schemes, hence helping to preserve seagrass meadows and the associated fish assemblages. Despite that, there are few studies investigating the relative contribution of environmental characteristics measured at different spatial scales in determining the distribution of seagrass fish. This study collects fish and environmental observations taken at both site and seascape scales in seagrass meadows in the Venice lagoon (Adriatic Sea, Italy). By means of generalised linear models, it aims to disentangle the relative influence of local water quality and habitat characteristics from that of habitat mosaic properties, investigating the response of whole fish assemblage descriptors, feeding guilds and dominant species. While confirming the primary importance of local habitat quality, the study highlights that also seagrass habitat structure at the seascape scale is relevant for seagrass fish assemblages, influencing total biomass, biomass of macrobenthivorous and hyperbenthivorous/piscivorous species and seagrass specialists such as syngnathids. Conservation of seagrass fish assemblages can therefore be promoted in Mediterranean coastal lagoons by preserving or restoring some features of the habitat mosaic, namely the extension of seagrass patches and their shape complexity, in addition to local water quality and seagrass cover.

Effectiveness of Living Shorelines as an Erosion Control Method in North Carolina Abstract Living shorelines are a shoreline stabilization strategy encompassing a range of vegetative to structural materials and serve as an alternative approach to the use of structures like bulkheads, which are known to aggravate erosion. Living shorelines are often installed with little to no long-term monitoring for effectiveness; specifically, there is a lack of quantitative data regarding their performance as a shoreline stabilization strategy. This study sought to assess the performance of living shorelines with sills, with respect to shoreline protection, by determining shoreline change rates (SCR) using geospatial analysis. Shoreline surveys were conducted using a real-time kinematic (RTK)-GPS unit at a total of 17 living shoreline projects and nine control segments at 12 sites along the coast of North Carolina. Current shoreline position was compared to historic (pre-installation) shoreline positions obtained from aerial imagery, dating to 1993. The average SCR among northern sites before installation was − 0.45 ± 0.49 m year−1, and in southern sites, it was − 0.21 ± 0.52 m year−1. After installation, average SCR was significantly less erosive at northern and southern sites with living shorelines, 0.17 ± 0.47 and − 0.01 ± 0.51 m year−1, respectively. Of the 17 living shoreline project segments, 12 exhibited a reduction in the rate of erosion; of those 12, six were observed to be accreting. This study supports the convention that living shorelines can reduce the rate of erosion and potentially restore lost shore zone habitat.

International Environmental Agreements: Politics, Law and Economics

Governing transboundary commons in Africa: the emergence and challenges of the Kavango–Zambezi Treaty Abstract The advent of ‘Peace Parks’ on the African continent is puzzling from the perspective of institutional theory. We focus on the world’s largest transfrontier conservation cooperation that exists to date, the Kavango–Zambezi Treaty, which was ratified by Angola, Botswana, Namibia, Zambia, and Zimbabwe in 2011. The collaboration seeks to foster sustainable governance of resources in the region. The paper asks two questions: What were the main factors facilitating the establishment of the Kavango–Zambezi Treaty? What potential challenges for the treaty remain on the operational level? Analysing interviews with key informants, we contribute by providing insights regarding the emergence and existing challenges of the treaty. Factors reducing coordination problems during the treaty’s establishment included that it did not compete with existing institutions at the international level, the important role played by moral authorities such as Nelson Mandela, and that consensus rather than conflict prevailed between respective political actors as they realized the function of this cooperation. The treaty is challenged by differences in macro-institutional factors amongst participating nations and a variation in the extent to which communities trust in and comply with these institutions. There are significant remaining obstacles with regard to harmonizing policies in the five partner countries.

How are Argentina and Chile facing shared biodiversity loss? Abstract Biodiversity loss remains one of the most pressing issues for global governance. This situation can be seen in Argentina and Chile through the effects of biodiversity loss caused by the introduction and expansion of beavers in Southern Patagonia. This case is interesting because, despite the Beagle conflict (i.e., the border dispute) between these countries some decades ago, nowadays Argentina and Chile are facing shared environmental problems and both are actively seeking solutions. The main question in this paper is, how did Argentina and Chile search for a solution to shared environmental problems caused by the expansion of beavers in Southern Patagonia? This paper tackles this question and presents the results of the conducted qualitative research. The results indicate that, in order to understand what Argentina and Chile are doing to achieve a solution to their shared environmental problems, research cannot be exclusively focus on domestic affairs. Instead, this issue requires taking into account how international dimensions influenced domestic policies. As this paper argues, in Argentina and Chile, international cooperation is a method of influencing biodiversity governance through funds granted by international organizations and international expert recommendations.

The European Union and the establishment of marine protected areas in Antarctica Abstract This paper examines how the EU can best use its powers to establish marine protected areas (MPAs) in Antarctica. It first discusses the EU’s role in Antarctic governance and legal basis for the EU’s actions, with particular focus on the pending Joined Cases C-625/15 and C-659/16 at the Court of Justice of the European Union. Secondly, the paper analyses the negotiation process of the EU’s MPA proposals in the Southern Ocean within the Commission for the Conservation of Antarctic Marine Living Resources. Thirdly, it provides suggestions regarding the EU’s potential actions that might help achieve proposed Antarctic MPAs.

Do deep and comprehensive regional trade agreements help in reducing air pollution? Abstract Environmental concerns are increasingly being incorporated into regional trade agreements (RTAs) to promote environmental quality and ultimately ensure compatibility between trade and environmental policies. This occurs in a context where air pollution and its effects on human health are of major concern. This paper investigates whether the proliferation and depth of environmental provisions (EPs) in RTAs are associated with lower concentration levels of particulate matter. We present an index of EPs in RTAs that measures the breadth and depth of the provisions and use it to estimate the effect of ratifying RTAs with different levels of EPs on changes in PM2.5 concentration levels in a panel of OECD countries over the 1999–2011 period. Using an instrumental variables strategy, we find that countries that have ratified RTAs with EPs show lower levels of PM2.5concentrations when we control for scale, composition and technique effects and for national environmental regulations. Moreover, the PM2.5 concentration levels in the pairs of countries that belong to an RTA with EPs tend to converge for the country sample. The results also hold for a longer period of time (1990–2011) and a broader sample of 173 countries as well as for other pollutants, namely CO2 and NO2.

The geopolitical overlay of the hydropolitics of the Harirud River Basin Abstract This paper explores the geopolitical overlay that is shaping dynamic hydropolitical interactions of the Harirud River Basin, which is a basin that spans Afghanistan, Iran and Turkmenistan. This paper argues that the control and capture of water resources are not solely for economic development but rather for geopolitical reasons that serve the security interests of the actors involved, particularly outside-basin powers like the US and India. The Afghan Government similarly views dams as symbols of nation-building and a way of staying in power. In the absence of a lasting trilateral agreement, the existing nature of the geopolitical dynamics of the basin has led upstream Afghanistan and downstream Iran and Turkmenistan to unilaterally establish their rights to control the “rules of the game”. This paper suggests that sustainable solutions will not be reached unless the geopolitical nature of the basin and outside interventions can center on a normative understanding of the regional interests, identities, and commonalities of all the riparian states.

A critique of the Global Pact for the environment: a stillborn initiative or the foundation for Lex Anthropocenae ? Abstract In May 2018, the process which may ultimately lead to the negotiation of a legally binding Global Pact for the environment formally commenced under the auspices of the United Nations General Assembly. Expectations for the Pact are high, evidenced in particular by its multiple and overlapping objectives: to serve as a generic binding instrument of international environmental law (IEL) principles; to integrate, consolidate, unify and ultimately entrench many of the fragmented principles of IEL; and to constitute the first global environmental human rights instrument. In the wake of the impending intergovernmental process, the paper offers a thorough critique of the draft Pact in its present iteration. We do so with the aim of evaluating the strengths and weaknesses of the present draft Pact by interrogating: (a) its diplomatic and symbolic relevance and possible unique contribution at the policy level to global environmental law and governance, and (b) its potential at the operational level of IEL and global environmental governance, focusing on the extent to which the draft Pact accommodates both existing and more recent rules and principles for environmental protection. As the Pact’s primary ambition is to become a universally binding global treaty, it would be churlish not to recognise its potential for innovation, as well as the considerable opportunity that the negotiation of the Pact will have to generate broad-sweeping and positive impacts. However, our central thesis is that only if the Global Pact were to incorporate ambitious normative provisions to strengthen those public and private global governance efforts that aim to halt the deterioration of Earth system integrity, as well as to maintain and improve integrity, will it be able to offer a firm foundation of the type of Anthropocene Law, termed here as the Lex Anthropocenae, required to confront head-on the deep socio-ecological crisis of the Anthropocene.

Enabling the IPBES conceptual framework to work across knowledge boundaries Abstract The IPBES conceptual framework (CF) serves an instrumental value to translate usable knowledge into policy across spatial scales, alongside a normative function to engage diverse knowledge systems, promoting inclusivity and enhancing legitimacy. It has been argued that the CF operates as a boundary object, a communication and organisation tool for those working across diverse knowledge systems, designed to help them reach shared goals. The paper focuses on this claim, exploring the three core characteristics of a boundary object: interpretive flexibility, material and organisational structure, and the recognition of dissention. We suggest that too much emphasis is placed within the CF upon interpretive flexibility, whilst meeting information needs and the work requirements of all individuals, groups and communities who use the CF are overlooked. By forcing consensus, the IPBES CF ignores the critical dimensions of a boundary object. We argue that embracing the full characteristics of a boundary object will enable the IPBES to support knowledge coproduction and translation across the knowledge systems, better achieving its goal of providing policy advice.

Correction to: The rational design of regional regimes: contrasting Amazonian, Central African and Pan-European Forest Governance Mistakenly, a prior, premature version of this article was published online, which did not reflect revisions made based on a last round of external peer review. The original article has been corrected.

The mismatch between the in-country determinants of technology transfer, and the scope of technology transfer initiatives under the United Nations Framework Convention on Climate Change Abstract Despite decades of international political emphasis, little is known about the in-country determinants of technology transfer for climate change mitigation. We draw upon the conclusions of a series of standardised, official governmental statements of technology priorities, coupled with questionnaire-based data collection, to shed light on the nature of those determinants. We find that there is a disconnect between what developing country governments perceive as the key enablers of, and barriers to, technology transfer, and what bilateral and multilateral technology transfer programmes can offer, given budgetary constraints and the logic of development aid spending. We show that the well-established notion of making climate change mitigation actions an integral part of sound development plans is especially relevant for technology transfer. We offer pointers as to how this might be done in practice, in the context of the ‘technology action plans’ developed as part of the United Nations-sponsored technology needs assessment process.

A proposed methodology for assessing the economic needs of safeguard zones protecting groundwater intended for human consumption within the context of the European Water Framework Directive Abstract This paper describes the gross domestic product and hydrological environment service method for assessing the socio-economic consequences of implementing necessary measures for safeguarding the quality of groundwater for human consumption and eliminating the risk of pollution. This method assesses the positive and negative impacts of designations of protected areas. Economic assets and social goods are the two integrated variables used in analysing the method. The first includes economic impacts on the local gross domestic product of defining protected areas, and the second considers the benefits of this designation in the conservation of water resources, assigning a monetary value to the preserved resources. In addition, tools have been incorporated, such as payment for hydrological services and generation of permissible activities, which reduce negative social impacts through positive economic impacts. These tools can only be used when compliance with conservation requirements for protected areas is demonstrated. The conclusions of this study include an application of the proposed methodology and provide essential and specific assessments that show that this methodology fulfils the requirements of the European Water Framework Directive requirements and that it is an effective tool in the implementation and development of strategies for hydrological planning processes.

Biometeorology

The significant role of health surveillance in the occupational heat stress assessment Abstract In order to address the heat stress hazard, the worker health surveillance makes a difference by providing information about individual factor, feedback, and evidence about efficacy of preventive measures and activities carried out through the risk assessment process, at individual and group levels. Every technical, procedural, or organizational measures could be ineffective without taking into account the results provided by health surveillance.

Coupling of urban energy balance model with 3-D radiation model to derive human thermal (dis)comfort Abstract While capabilities in urban climate modeling have substantially increased in recent decades, the interdependency of changes in environmental surface properties and human (dis)comfort have only recently received attention. The open-source solar long-wave environmental irradiance geometry (SOLWEIG) model is one of the state-of-the-art models frequently used for urban (micro-)climatic studies. Here, we present updated calculation schemes for SOLWEIG allowing the improved prediction of surface temperatures (wall and ground). We illustrate that parameterizations based on measurements of global radiation on a south-facing vertical plane obtain better results compared to those based on solar elevation. Due to the limited number of ground surface temperature parameterizations in SOLWEIG, we implement the two-layer force-restore method for calculating ground temperature for various soil conditions. To characterize changes in urban canyon air temperature (Tcan), we couple the calculation method as used in the Town Energy Balance (TEB) model. Comparison of model results and observations (obtained during field campaigns) indicates a good agreement between modeled and measured Tcan, with an explained variance of R2 = 0.99. Finally, we implement an energy balance model for vertically mounted PV modules to contrast different urban surface properties. Specifically, we consider (i) an environment comprising dark asphalt and a glass facade and (ii) an environment comprising bright concrete and a PV facade. The model results show a substantially decreased Tcan (by up to − 1.65°C) for the latter case, indicating the potential of partially reducing/mitigating urban heat island effects.

Temperature sensitivity of willow dwarf shrub growth from two distinct High Arctic sites Abstract The High Arctic region has experienced marked climate fluctuations within the past decades strongly affecting tundra shrub growth. However, the spatial variability in dwarf shrub growth responses in this remote region remains largely unknown. This study characterizes temperature sensitivity of radial growth of two willow dwarf shrub species from two distinct High Arctic sites. The dwarf shrub Salix arctica from Northern Greenland (82°N), which has a dry continental High Arctic climate, is linked with Salix polaris from central Svalbard (78° N), which experiences a more oceanic High Arctic climate with relatively mild winters. We found similar positive and significant relationships between annual growth of both Salix dwarf shrub species and July–August air temperatures (1960–2010), despite different temperature regimes and shrub growth rates at the two sites. Also, Salixdwarf shrub growth was significantly negatively correlated with Arctic and North Atlantic Oscillation (AO/NAO) indices; S. arctica from Northern Greenland was negatively correlated with previous autumn (AO index) and current summer AO and NAO indices, and S. polaris with the summer NAO index. The results highlight the importance of both local and regional climatic drivers for dwarf willow shrub growth in harsh polar desert habitats and are a step in the direction of identifying and scaling changes in plant growth across the High Arctic.

Analysis of meteorological dryness/wetness features for spring wheat production in the Ili River basin, China Abstract Understanding the impacts of climate change on crop yield is important for improving crop growth and yield formation in northwestern China. In this study, we evaluated the relationship between meteorological dryness/wetness conditions and spring wheat yield in the Ili river basin (IRB). The climate and yield data from 1961 to 2013 were collected to analyze characteristics and correlations between these two variables using the standardized precipitation evapotranspiration index (SPEI), yield detrending method, modified Mann-Kendall test and Spearman correlation analysis. Main results were as follows: (1) correlations between monthly SPEI values (MSV) and climatic yield of spring wheat indicated that the dryness/wetness condition in May was a key factor affecting yield in the whole region; (2) although the MSV in May and yield fluctuated from negative to positive values in time, the severely and extremely dryness events were in good agreement with the higher yield losses; (3) each increase of 0.5 MSV in May promoted over 3% increase of yield in most part of IRB; however, the larger variability of MSV in May resulted in larger yield fluctuations; and (4) the Tibetan Plateau index in April showed significant correlations with the MSV in May and yield, which provided a precursory signal for decision-makers to better understand potential yield fluctuations.

Associations between ambient temperature and daily hospital admissions for rheumatic heart disease in Shanghai, China Abstract Rheumatic heart disease (RHD) remains a serious public health burden in developing countries. We conducted a time-series study to explore the association between ambient temperature and daily hospital admissions for RHD in Shanghai, China. We collected data on daily hospital admissions for RHD from 2013 to 2015 from the database of Shanghai Health Insurance System. We applied the generalized additive models together with the distributed lag nonlinear model to estimate the association between temperature and RHD hospital admissions after controlling for relative humidity, time trend, day of the week, and holidays. Stratification analyses by age and gender were performed to evaluate their potential effect modification. A total of 4178 cases of RHD hospitalizations were identified over the study period. There were almost linear, positive, and significant associations between daily mean temperature and RHD hospital admissions with higher risks at hotter days. Compared to reference temperature (0 °C), the cumulative risks of moderate heat (the 90th percentile of temperature, 28.0 °C) and extreme heat (the 99th percentile of temperature, 33.5 °C) over lags 0–5 days were 2.55 (95% confidence interval 1.14, 5.73) and 3.22 (95% confidence interval 1.36, 7.61), respectively. These associations were significantly stronger in older people than in younger people. This study indicated larger risks of RHD hospital admissions associated with higher temperature, especially in older people. Our findings provided first-hand epidemiological evidence regarding the effects of ambient temperature on RHD incidence.

The spatial distribution of BUN reference values of Chinese healthy adults: a cross-section study Abstract The blood urea nitrogen (BUN) is generally regarded as a significant serum marker in estimating renal function. This study aims to explore the geographical distribution of BUN reference values of Chinese healthy adults, and provide a scientific basis for determining BUN reference values of Chinese healthy adults of different regions according to local conditions. A total of 25,568 BUN reference values of healthy adults from 241 Chinese cities were collected in this study, and 17 geographical indices were selected as explanatory variables. The correlation analysis was used to examine the significance between BUN reference value and geographical factors, then five significant indices were extracted to build two predictive models, including principal component analysis (PCA) and support vector regression (SVR) model, then the optimal model was selected by model test to predict BUN reference values of the whole China, finally the distribution map was produced. The results show that BUN reference value of Chinese healthy adult was characteristically associated with latitude, altitude, annual mean temperature, annual mean relative humidity, and annual precipitation. The model test shows, compared with SVR model, the PCA model possesses superior simulative and predictive ability. The distribution map shows that the BUN reference values of Chinese healthy adult are lower in the east and higher in the west. These results indicate that the BUN reference value is significantly affected by geographical environment, and the BUN reference values of different regions could be seen clearly on distribution map.

Assessment of the Australian Bureau of Meteorology wet bulb globe temperature model using weather station data Abstract Exertional heat illnesses affect thousands of athletes each year and are a leading cause of death in sports. The wet bulb globe temperature (WBGT) is widely used as a heat stress metric in athletics for adjusting activities. The WBGT can be measured on-site with portable sensors, but instrument cost may provide a barrier for usage. Modeling WBGT from weather station data, then, presents an affordable option. Our study compares two WBGT models of varying levels of sophistication: the Australian Bureau of Meteorology (ABM) model which uses only temperature and humidity as inputs and a physically based model by Liljegren that incorporates temperature, humidity, wind speed, and solar radiation in determining WBGT outputs. The setting for the study is 19 University of Georgia Weather Network stations selected from across the state of Georgia, USA, over a 6-year period (2008–2014) during late summer and early fall months. Results show that the ABM model’s performance relative to the Liljegren model varies based on time of day and weather conditions. WBGTs from the ABM model are most similar to those from the Liljegren model during midday when the assumption of moderately high sun most frequently occurs. We observed increasingly large positive biases with the ABM model both earlier and later in the day during periods with lower solar radiation. Even during midday, large (≥ 3 °C) underestimates may occur during low wind conditions and overestimates during periods with high cloud cover. Such differences can lead to inaccurate activity modification and pose dangers for athletes either by underestimating heat-related hazards or by imposing an opportunity cost if practice activities are limited by overestimating the heat hazard.

Grain development and endogenous hormones in summer maize ( Zea mays L.) submitted to different light conditions Abstract Low light is a type of abiotic stress that seriously affects plant growth and production efficiency. We investigated the response mechanisms of summer maize to low light by measuring the changes in endogenous hormones in the grains and during grain filling in summer maize at different light intensities to provide a theoretical basis for the production and management of summer maize under light stress. We applied different light treatments in a field experiment as follows: S, shading from tassel stage (VT) to maturity stage (R6); CK, natural lighting in the field; and L, increasing light from VT to R6. The shading level was 60%, and the maximum illumination intensity of the increasing light treatment on cloudy days was 1600–1800 μmol m−2 s−1. Compared with the control, shading significantly increased the grain abscisic acid (ABA) content at 5–20 days after pollination and decreased the indole acetic acid (IAA), zeatin riboside (ZR), and gibberellin (GA) contents (P < 0.05). The grain-filling rate decreased under shading conditions. Meanwhile, the grain volume, grain weight, and yield all decreased; the yields in 2013 and 2014 decreased by 61 and 60%, respectively. The grain IAA, ZR, and GA contents were increased by increasing light. The grain ABA content at 5–20 days after pollination did not significantly differ from that of CK (P < 0.05). After 20 days after pollination, the ABA content decreased, the grain-filling rate and the filling duration increased, and the yield increased. However, shading after anthesis increased the grain ABA content and reduced the IAA, ZR, and GA contents. Grain growth and development were inhibited, and the yield decreased. The grain ABA content decreased; the IAA, ZR, and GA contents increased; and the yield increased after increasing light. The results indicate that different light intensities regulated the levels of grains endogenous hormones, which influenced the grain-filling rate and duration, and consequently, regulated grain weight and yield.

Balneotherapy in chronic inflammatory rheumatic diseases—a narrative review Abstract Since ancient time, thermal baths and mudpacks have been used as treatments for rheumatic diseases and other musculoskeletal complaints. Despite basic researches suggest an anti-inflammatory effect of spa therapy, there is no consensus about the benefits of balneotherapy in patients with chronic inflammatory rheumatic diseases. The aim of this review is to summarize the currently available information on clinical effects of balneotherapy in these diseases. We did a literature search for articles considering the randomized controlled trials (RCTs) published until today. Although many selected studies do not have an elevated methodological quality, data from these RCTs support a beneficial effect of spa therapy. Balneotherapy highly improves the clinical course of the disease in patients with predominant axial involvement, such as with ankylosing and enteropathic spondylitis; the effects are less favorable in patients with predominant peripheral articular inflammation, such as rheumatoid arthritis. Good results have been observed in patients with psoriatic arthritis, but only few RCTs have been conducted on this disease. Spa therapy appears safe, and adverse events have been reported only in a few patients.

Simple method to detect year-to-year variability of blooming phenology of Cerasus × yedoensis by digital camera Abstract The year-to-year variability of the blooming phenology of cherry trees is important as a proxy climate indicator and strongly affects cultural ecosystem services. Observation of blooming phenology at multiple points requires a simple and flexible approach. We examined changes in the canopy gap fraction extracted from binarized upward images taken periodically beneath a Cerasus × yedoensis ‘Somei-yoshino’ tree. The gap fraction decreased rapidly after the start of bloom, reached a minimum value at full bloom, and began to increase again, but then decreased rapidly during leaf flush. These changes reflect the phenology of blooming and leaf flush after flower drop of ‘Somei-yoshino’. These characteristics allow detection of the year-to-year variability of the bloom and leaf-flush phenology of cherry and other deciduous tree species that show the same patterns.

Soils and Sediments

Evolution over years of structural characteristics of humic acids in Black Soil as a function of various fertilization treatments Abstract Purpose Humic substances are the relatively stable and recalcitrant pool of soil organic carbon in the agricultural system. Humic acid (HA) is an active part of soil humic substances. However, little information exists on how structural characteristics of HA evolved with fertilization years in Black Soil. Materials and methods Soil samples were collected in 1997, 2002, 2008, and 2012 from the Long-term Fertilization Station of Black Soil. The methods of 13C-nuclear magnetic resonance spectroscopy, elemental composition analysis, and infrared spectroscopy were employed to analyze the structure of HA. Results and discussion Long-term fertilization had no significant (P > 0.05) effect on the ratio of O and S to C in HA. The ratio of H to C in HA increased with fertilization years after the application of organic manure (M) single or combined with chemical NPK fertilizers. The ratios of aliphatic C to aromatic C, and alkyl C to O-alkyl C in soil HA increased by 7.72% and 20.3%, respectively, in MNPK and M treatments, whereas NPK treatment declined the ratio of aliphatic C to aromatic C by 2.67% compared with CK treatment. Conclusions The HA structure tends to become aliphatic and simplified with years of organic manure combined with NPK fertilizers. To save costs, organic manure was only applied once within the period of crop rotation and was combined with NPK every year to satisfy crop demands for soil nutrients.

Intercropping with sweet corn ( Zea mays L. var. rugosa Bonaf.) expands P acquisition channels of chili pepper ( Capsicum annuum L.) via arbuscular mycorrhizal hyphal networks Abstract Purpose Intercropping of chili pepper (Capsicum annuum L.) with corn (Zea mays L.) is one of the main valuable intercropping patterns. However, the potential contribution of arbuscular mycorrhizal (AM) fungal hyphal networks is still poorly understood. The purpose of this work was to resolve the changes of AM fungal propagation and colonization in the pepper/corn intercropping systems due to the constitution of hyphal networks and the networks’ effects on plant nutrient uptake and interspecific competitive relations. Materials and methods An 18-week pot experiment on an unsterilized soil was carried out to test mycorrhizal performance and P acquisition of chili pepper and sweet corn (Zea mays L. var. rugosa Bonaf.) in two compartments, which were absolutely separated (Sep) by polyvinyl chloride (PVC) layer or semi-separated (Semi-Sep) by nylon mesh (30 μm) screen that only allows the passage of AM fungal hyphae but not plant roots. Root mycorrhizal colonization rates and the biomasses and P concentrations of shoots, roots, and fruits of pepper and corn were all measured. The total P acquisition of each crop per pot and the acquisition ratio of one to two crops were assessed. Soil pH, organic C, total P, available P, AM fungal abundance, and acid phosphatase activity were also tested. Results and discussion In the Sep system, root mycorrhizal colonization, P acquisition amount, shoot biomass, and rhizosphere AM fungal abundance of corn were all higher (P < 0.05) than those of pepper, but soil available P concentration was lower (P < 0.05) in corn compartment than in pepper one. Compared with Sep, Semi-Sep had higher (P < 0.05) mycorrhizal colonization rates with both intercrops and higher (P < 0.05) soil acid phosphatase activity and AM fungal abundance in corn and pepper compartments, respectively. Semi-Sep decreased (P < 0.05) soil available P concentrations with both compartments, but did not narrow the difference of soil available P concentration between compartments, suggesting there was no gradient diffusion of soil available P between compartments. Semi-Sep increased (P < 0.05) the P acquisition ratio and fruit yield of pepper, but not corn. Conclusions Constitution of hyphal networks increased mycorrhizal colonization with both intercrops, and corn supplied part of photosynthetic C for increasing AM fungal propagules in pepper compartment by gradient expansion since AM fungi formed better symbioses with corn. Hyphal networks increased pepper fruit yield via improving P distribution to pepper, but acquired relatively higher P from corn compartment via elevating the soil acid phosphatase activity, suggesting enhanced P competitive ability of pepper against corn upon hyphal networks.

Effects of topography on soil organic carbon stocks in grasslands of a semiarid alpine region, northwestern China Abstract Purpose Soil organic carbon (SOC) in mountainous regions is characterized by strong topography-induced heterogeneity, which may contribute to large uncertainties in regional SOC stock estimation. However, the quantitative effects of topography on SOC stocks in semiarid alpine grasslands are currently not well understood. Therefore, the purpose of this research study is to determine the role of topography in shaping the spatial patterns of SOC stocks. Materials and methods Soils from the summit, shoulder, backslope, footslope, and toeslope positions along nine toposequences within three elevation-dependent grassland types (i.e., montane desert steppe at ~ 2450 m, montane steppe at ~ 2900 m, and subalpine meadow at ~ 3350 m) are sampled at four depths (0–10, 10–20, 20–40, and 40–60 cm). SOC content, bulk density, soil texture, soil water content, and grassland biomass are determined. The general linear model (GLM) is employed to quantify the effects of topography on the SOC stocks. Ordinary least squares regressions are performed to explore the underlying relationships between SOC stocks and the other edaphic factors. Results and discussion In accordance with the present results, the SOC stocks at 0–60 cm show an increasing trend in respect to the elevation zone, with the highest stock being approximately 37.70 g m−2 in the subalpine meadow, about 2.07 and 3.41 times larger than that in the montane steppe and montane desert steppe, respectively. Along the toposequences, it is revealed the SOC stocks are maximal at toeslope, reaching to 14.98, 31.76, and 49.52 kg m−2, which are also significantly larger than those at the shoulder by a factor of 1.38, 2.31, and 1.44, in montane desert steppe, montane steppe, and subalpine meadow, respectively. Topography totally is seen to explain about 84% of the overall variation in SOC stocks, of which 70.61 and 9.74% are attributed to elevation zone and slope position, while the slope aspect and slope gradient are seen to plausibly explain only about 1.84 and 0.01%, respectively. Conclusions The elevation zone and the slope position are seen to markedly shape the spatial patterns of the SOC stocks, and thus, they may be considered as key indicating factors in constructing the optimal SOC estimation model in such semiarid alpine grasslands.

Biodegradation of humic substances by microscopic filamentous fungi: chromatographic and spectroscopic proxies Abstract Purpose The study of interactions between humic substances (HSs) and soil filamentous fungi is the key to understanding the sustainable soil functioning. The present work aims to examine the decomposition of HSs by filamentous dark-pigmented fungus Alternaria alternatа under the laboratory conditions and to determine the effect of easily assimilable organic carbon on this process. Analyzing such polydisperse substances like HSs by a complex integrated methodology makes it possible to explore the data on their decomposition by microorganisms. Materials and methods To achieve the aforementioned goals, we used chromatographic and spectroscopic approaches: low-pressure size-exclusion and hydrophobic interaction chromatography accompanied by absorption and fluorescence spectroscopy. To determine the effect cometabolism conditions produced on HS decomposition, two types of carbon substrates were added to the nutrient media: easily assimilable organic carbon (standard 0.3% or reduced 0.03% sucrose content) and hardly assimilable organic carbon (HSs), as well as their combinations. Five HS samples of different organic matter origin have been inspected: potassium humates (HPs) and humic acids (HAs) from coal, peat, and lignosulfonate. Correlation matrix and principal component analysis (PCA) were calculated for comprehensive data analysis. Results and discussion Transformations of the investigated HSs under fungal cultivation lead to the increase in the low molecular weight fraction, rise of hydrophilic fraction, enlargement of absorbance ratio A250/A365, shortening of the emission wavelength of the humic-type fluorescence, and growth in the fluorescence quantum yield measured with excitation at 355 nm. A positive correlation was observed between the accumulation of fungal biomass and the degree of HS decomposition. PCA analysis confirms that the difference in the results of HS decomposition largely depends on the sucrose content and the nature of HSs. We divided all the HS samples into four groups according to the degree of HS decomposition: original HS solutions, HPs altered using fungal cultivation at 0.03% sucrose, HAs after fungal cultivation at 0.03% sucrose, and finally, HSs (both HPs and HAs) after fungal cultivation at 0.3% sucrose. Conclusions In the laboratory experiments, we showed that (1) the isolated HAs were more effectively degraded than the parent HPs, and this process was more pronounced at a reduced sucrose content, and (2) the decomposition of stable organic compounds (HSs) was activated by the easily assimilable carbon sources (especially 0.3% sucrose) being present. We assume that it is the easily assimilable organic carbon that most likely triggers the HS degradation working as the priming effect in natural environments.

Understanding the mechanisms of soil water repellency from nanoscale to ecosystem scale: a review Abstract Purpose Soil water repellency (SWR) can interrupt water infiltration that may decline plant growth and potentially trigger soil erosion. Until now research has been mainly focused on understanding the mechanisms of SWR at different scales by observation and modelling studies. Materials and methods This review systematically discusses the possible mechanisms at different scales of the occurrence and persistence of SWR from nanoscale to ecosystem scale. Results and discussion Soil characteristics are strongly related to the severity of SWR, particularly in soil organic matter and soil moisture. The presence of a higher amount of hydrophobic organic compounds and lower soil moisture content lead to higher water repellency, suggesting that the interaction at the nanoscale between organic compounds and water molecules primarily determines the persistence of SWR. The repeated alternation of drying-wetting process largely modifies the relationship between water molecules and soil particles that impacts the possibility of SWR from hydrophilic in wet condition to hydrophobic in dry condition. Within ecosystem scale, vegetation and microbes are original sources of SWR-inducing compounds influencing the distribution and prevalence of SWR. Nevertheless, the challenge of global climate change, drought and warming can increase SWR. Extreme SWR induces more serious runoff and overland flow that is enhanced by intensive precipitation. Conclusions We conclude that understanding the interaction of water molecules and organic compounds at soil particle surface is essential to understand SWR at the nanoscale. Expanding the mechanisms of SWR from nanoscale to a larger scale is fundamental to improve the remediation of soil pollution and mitigate global change.

Using 137 Cs and 210 Pb ex measurements to explore the effectiveness of soil conservation measures in semi-arid lands: a case study in the Kouhin region of Iran Abstract Purpose One of the most fragile agro-ecosystems in Iran is represented by dry farming lands on steep hillslopes that occupy ca. 54% of the national agricultural lands. Therefore, in order to reduce loss of fertile soil from these lands, it is important to apply effective soil conservation strategies. This study used cesium-137 (137Cs) and excess lead-210 (210Pbex) measurements to assess the effectiveness of soil conservation practices in controlling soil erosion in Kouhin, Qazvin Province of Iran. Materials and methods Soil samples were collected from two adjacent hillslopes with and without conservation agriculture practices. The managed site benefited from conservation practices, including controlled grazing, terraces, and contour farming for 50 years. The unmanaged site was under cultivation without agricultural conservation practices. At the managed site, both 137Cs and 210Pbex activities were measured. Only 137Cs activity was measured for the unmanaged site. Results and discussion Conservation practices performed at the managed site were effective in minimizing soil erosion, i.e., net soil erosion rates provided by 137Cs measurements were only 4.6 Mg ha−1 year−1 at the managed site, compared to 12 Mg ha−1 year−1 for the unmanaged site. By using the 210Pbex approach, net soil loss and sediment delivery ratio in the managed site were 12.3 Mg ha−1 year−1 and 60%, respectively. Conclusions Soil redistribution magnitudes established from 137Cs inventories are associated with a period extending from 1963 to the time of sampling, while those obtained from 210Pbex measurements are related to the past 100 years. However, 210Pbex measurements are expected to be more sensitive to erosive events that occurred during the last 15 to 20 years and this could reflect the higher estimate of erosion rate provided by this radionuclide for the managed site. The increasing trend seems to suggest a possibility that the higher soil losses estimated by the 210Pbex measurements are a result of increasing climate variability during the last two decades. However, further investigation would be needed to confirm this hypothesis.

Improvement of mining soil properties through the use of a new bio-conditioner prototype: a greenhouse trial Abstract Purpose The effect of a prototype of humic bio-conditioner (H-BC) was assessed on the development of edaphic properties and the growth of maize plants in an edaphic material used as topsoil in the rehabilitation of soils in a coal mine in Colombia. Materials and methods The trial was carried out in a greenhouse, using pots with edaphic material treated with the addition of doses equivalent to 0 (control), 1, 2, and 4 Mg.ha−1 of H-BC; maize seeds were sown and followed up on for 60 days. Plant growth and soil biological, chemical, and physical variables were registered. Results and discussion The 4-Mg.ha−1 treatment maintained a significantly higher enzymatic activity than the control on day 60. The respiration of the soil treated with H-BC increased significantly, with the 4-Mg.ha−1 treatment standing out. The 2-Mg.ha−1 treatment induced the most noticeable changes in soil metabolic activity profiles. Increases in root and leaf development were observed in the treatment with 4 Mg.ha−1; apparently, this dose improved the absorption of Ca, K, and S by plants; the physical and soil aggregation indices increased significantly with 4 Mg.ha−1. Conclusions The results indicate that H-BC can be an alternative as an enhancer of the edaphic material used in soil rehabilitation processes.

Ammonia-oxidizing bacterial and archaeal communities in tropical bioaugmented zero water exchange shrimp production systems Abstract Purpose Ammonia oxidation is an important process in the removal of ammonia generated from feed and metabolic wastes in aquaculture systems. Considering the biogeochemical importance of ammonia oxidation in bioaugmented zero water exchange aquaculture systems, the diversity and abundance of bacterial and archaeal ammonia-oxidizing communities were analyzed in three selected ponds at different time intervals during the culture period, to unravel the key environmental factors influencing their distribution in the system. Materials and methods The diversity and abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in three tropical bioaugmented zero water exchange (ZWE) shrimp culture systems were analyzed using ammonia monooxygenase A (amoA) gene from the sediment metagenome during different phases of culture. The environmental factors associated with the variability in bacterial and archaeal amoA gene abundance and diversity were elucidated using RDA and Pearson correlation analysis. Results and discussion Ammonia-oxidizing archaea (AOA), Nitrosopumilus sp., Nitrosospharea sp., and ammonia-oxidizing bacteria (AOB), Nitrosomonas sp., were the dominant ammonia-oxidizing communities in the ZWE ponds studied. AOA shared 41 OTUs, and the maximum distribution was influenced by dissolved oxygen in the system, whereas AOB shared 4 OTUs. The copy numbers amoA gene determined using qPCR showed that the AOA amoA gene was 10- to 100-fold abundant than AOB amoA gene. Gene abundance of AOA was positively related to total organic carbon (TOC) and salinity of sediments, and the temperature had a negative impact on bacterial amoA gene abundance. The dissolved oxygen and TOC had a negative and redox potential a positive impact on the diversity of AOA, whereas pH had a negative impact on the diversity of AOB. Conclusions The ammonia-oxidizing archaeal communities dominated the bioaugmented zero water exchange aquaculture systems compared to bacteria based on the abundance and diversity analysis using amoA gene sequence-based OTU analysis and gene copy numbers. Dissolved oxygen, total organic carbon, and Eh of the sediments contributed to the distribution and abundance of AOA group in the ZWE ponds. This study points to the importance of environmental management in these culture systems for maintaining ammonia-oxidizing populations for optimal ammonia removal. The relative contribution of the archaea and bacteria to ammonia oxidation in these systems is to be further resolved along with that of anammox and comammox bacteria, which would help to develop appropriate biostimulation or bioaugmentation strategies for the management of these sustainable aquaculture production systems.

Edwin David Ongley (1941–2015)

Chemical patterns in sediments of ancient Theodosius Harbour (Istanbul) Abstract Purpose The use of fossil fuels, cement production and the reduction of forest areas cause a high amount of CO2 emissions to the atmosphere which in turn causes the ocean to be acidified. Acidity of seawater can directly change sediment properties. It is expected that the average pH value of the ocean surface water will decrease between 0.3 and 0.5 pH units according to the projection to year 2100. This study aimed to make a contribution to the understanding of long-term pollution trends. In the study, sediment samples from Neolithic Era, Early Byzantine Era and Byzantine Era from archaeological excavations jointly conducted by Istanbul Archaeological Museums and the Istanbul University Department of Conservation of Underwater Cultural Heritages were investigated. Materials and methods The sediment samples were taken from ancient Theodosius Harbour (5000 BC). Major elements (Si, Al, Fe, Mg, Ca, K, Na, Mn, Ti), rare earth elements (Tb, Yb, Eu, Dy, Tm) and toxic elements (As, Cr, Co, Cu, Ni, Pb and Zn) in sediment samples were determined by X-ray fluorescence spectrometer. The chemical abundance of the ancient sediments was evaluated with the ecological risk factor and geo-accumulation index. Results and discussion The sediment samples from the Neolithic Era reflect the contribution of both parent rock and also anthropogenic pollution. In the Early Byzantine and Byzantine Era, the development of the industry has increased the basic element concentrations in the environment and potential ecological risk and geo-accumulation indices. As, Cu, Cr, Zn, Ni and Co contents of Neolithic Era samples were found to be lower than Early Byzantine and Byzantine Era. Conclusions The obtained the results showed that the toxic elements in the Neolithic Era, which the industry never developed, started to rise and increased concentrations of Ni by about two and a half times, Zn four times, Pb two times, Cr two times, Co six times and As three times in the Early Byzantine and Byzantine Eras. The concentrations of major elements (Al, Ba, Ca, Fe, K, Mg, Mn, Na, Si) did not show any significant difference during these three eras.