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This study presents a comprehensive analysis of the hydrochemistry of the Tendrara aquifer in the Tendrara region of Morocco. The study encompasses various aspects of the region, including its geography, administration, relief, demography, economy, and climate, to establish a solid understanding of its water facies. Ten water sampling points have been chosen, and standard methods were used to analyze the physicochemical characteristics of the water, temperature, electrical conductivity, and concentrations of different ions and compounds. Descriptive statistics and hydrochemical classifications, including Piper's, Schoeler's, Wilcox's, and ternary classification, were applied to classify and identify different water facies. Additionally, principal component analysis (PCA) was conducted to explore the relationships between different water parameters. The results revealed distinct hydrochemical characteristics within the Tendrara aquifer, with predominantly alkaline water and varying concentrations of potassium, sodium, calcium, magnesium, chlorides, nitrates, bicarbonates, and sulfates. The numerical results indicated that the concentrations of major ions in the Tendrara aquifer varied within the following ranges: potassium (K+) 2.6-47 mg/l, sodium (Na+) 17-170 mg/l, calcium (Ca2+) 40.882-178 mg/l, magnesium (Mg2+) 33.534-159.72 mg/l, chlorides (Cl-) 22.865-244.201 mg/l, nitrates (NO3-) 2.806-237.85 mg/l, bicarbonates (HCO3-) 183-311.1 mg/l, and sulfates (SO42-) 40.392-336.6 mg/l. The electrical conductivity of the water ranged from 660 to 2640 μS/cm, indicating variations in mineral content and overall water quality analysis of the diagram shows that the Tendrara aquifer's subterranean waters are predominantly chloride-rich and sulfate-rich in calcium and magnesium. These findings contribute to a better understanding of the hydrochemistry of the Tendrara aquifer and have implications for water resource management in the region. The knowledge gained from this study can inform decision-making processes related to water treatment, conservation, and protection. It highlights the need for sustainable practices to ensure the availability of clean and safe water for the local population. Further research is recommended to investigate temporal variations, sources of contamination, and the long-term impacts of anthropogenic activities on the Tendrara aquifer's hydrochemistry. [ABSTRACT FROM AUTHOR]

The Qujiang River Basin is a significant water system located in Zhejiang Province, China, that serves as a primary water source for Quzhou City. For this research, we collected and examined water samples from the Qujiang River Basin. In this study, we collected and analyzed water samples from the Qujiang River Basin and employed a combination of methods, including water balance analysis; Piper trilinear diagram; Gibbs diagram; and environmental tracer techniques, such as hydrochemical and isotopic analysis. These techniques helped us to analyze the spatial distribution patterns and evolutionary trends of surface water and groundwater hydrochemistry, along with the stable isotopes of hydrogen and oxygen, as well as to determine the sources of surface water and groundwater by calculating the conversion ratio between surface water and groundwater. (1) The findings of our study indicate that the primary hydrochemical types in the study area are Ca-HCO3 and Ca-HCO3·Cl, with the ion composition of water primarily influenced by rock weathering and precipitation. (2) Similar spatial variations in hydrochemical indicators were observed between surface water and groundwater in the study area, with frequent transitions between the two. (3) The hydrogen and oxygen isotope content increases downstream, signifying that both groundwater and surface water in the study area are replenished by atmospheric precipitation, as supported by the relationship between hydrogen and oxygen isotopes and the meteoric water line. (4) We determined that groundwater predominantly replenishes surface water in the upstream area. The average contribution rate of groundwater to surface water is 19.67%, with an annual average recharge volume of 1.23 × 106 m3. Midstream and downstream, surface water mainly recharges groundwater, with an average contribution rate of 22.77% and an annual average recharge volume of 1.59 × 106 m3. [ABSTRACT FROM AUTHOR]

The Indian Punjab state is drained by the four rivers, along with a well-connected network of canals, and is now dealing with a slew of water quality issues and problems. In this study, basin-wise hydrogeochemical modelling of 323 groundwater samples and identification of NO3– and F– enrichment pathways in aquifer systems of Punjab were studied using different plots and multivariate statistics. To evaluate the groundwater quality and human health risks, an entropy-based water quality index and Monte Carlo simulation were used, respectively. Spatial distribution of NO3– indicated that its very high values were prominent in parts of southwestern Punjab falling under LSRB, along with few pockets in eastern and northeastern Punjab falling under MSRB and GRB. High NO3– values (> 45.0 mg/L) were found in 15.0% of Ravi River Basin (RRB) groundwater samples, 22.86% of Beas River Basin (BRB), 23.52% of Middle Sutlej River Basin (MSRB), 36.9% of Lower Sutlej River Basin (LSRB), and 21.31% of Ghaggar River Basin (GRB). The spatial distribution of NO3– revealed elevated concentrations (> 100 mg/L) in the southwestern part of Punjab, particularly in LSRB and localized pockets in the eastern and northeastern areas of Punjab within MSRB and GRB. High F– concentration (> 1.5 mg/L) was observed in 15.12% and 21.31% groundwater samples of LSRB and GRB, respectively. Spatially southern parts falling under LSRB and GRB reflected high F– content (> 1.5 mg/L) in groundwater. In LSRB, evaporative and anthropogenic processes influence the groundwater quality. The results of interionic relationships and statistical analysis revealed that NO3– has anthropogenic origin and that is being aggravated by leaching, the evaporation processes, animal excreta, septic tanks and irrigation return flows in LSRB and GRB, while F– is geogenic in nature. Hazard index (HI) values in 14.63%, 22.2%, 24.6%, 49.58%, and 34.42% samples for adults and 21.95%, 27.7%, 42.0%, 72.3%, and 52.46% samples for children were higher than unity in RRB, BRB, MSRB, LSRB, and GRB, respectively. The basin-wise demarcation of various groundwater quality parameter and assessment of human health risk would be of significance for the management of water resources. [ABSTRACT FROM AUTHOR]

This case drew national attention in 2018. About 100 people died and more than 300 hospitalized in a span of few years in a village of 1200 people in a tribal stretch in central India. Medical teams visiting the area reported severe renal failure and blamed the local eating and drinking habits as causative factors. This human health assessment based on geochemical investigations finds nitrate (NO3−) and fluoride (F−) pollution as well in village's groundwater. Both deterministic and probabilistic techniques are employed to decipher the contamination pathways and extent of contamination. Source apportionments of NO3− and F− and their relationship with other ions in groundwater are carried out through chemometric modelling. Latent factors controlling the hydrogeochemistry of groundwater too are explored. While hazard quotients ( HQ ) of the chemical parameters ( H Q NO 3 - and H Q F - ) identify ingestion as the prominent pathway, the calculated risk certainty levels (RCL) of the hazard index (HI) values above unity are compared between the deterministic and probabilistic approaches. Deterministic model overestimates the HI values and magnify the contamination problems. Probabilistic model gives realistic results that stand at infants ( H I NO 3 - = 34.03%, H I F - = 24.17%) > children ( H I NO 3 - = 23.01%, H I F - = 10.56%) > teens ( H I NO 3 - = 13.17%, H I F - = 2.00%) > adults ( H I NO 3 - = 11.62%, H I F - = 1.25%). Geochemically, about 90% of the samples are controlled by rock-water interaction with Ca2+–Mg2+–HCO3− (~ 56%) as the dominant hydrochemical facies. Chemometric modelling confirms Ca2+, Mg2+, HCO3−, F−, and SO42− to originate from geogenic sources, Cl− and NO3− from anthropogenic inputs and Na+ and K+ from mixed factors. The area needs treated groundwater for human consumption. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) are a key component of the earth system, and intentionally and unintentionally produced in human activities. These NPs may have both positive and negative consequences to the environment. Recognizing their critical roles and integrating these understandings into earth process models will facilitate the management strategies and sustainable development of nanotechnologies. This chapter focuses on the currently understanding and research demands of NPs cycling in terrestrial systems. The generation and categorization of various NPs are firstly discussed to facilitate the following discussions on different types of NPs. The physical, chemical, and biological processes involved in NPs cycling are discussed in details. The unique process for NPs is their aggregation among the same type of NPs or with other types of particles. The impacts of the controlling water chemistry conditions, biological activities and natural organic matter are all discussed. The techniques to separate and identify (both qualitatively and quantitatively) NPs from environmental matrixes are compared and evaluated. We emphasize that the environmental implications of NPs need to be evaluated based on their life cycle assessments (LCA). The currently available models to describe NPs LCA are summarized. The challenges regarding NPs LCA are extensively discussed. With all these discussions, we proposed several points that need to be considered when investigating NPs cycling. This chapter will provide a comprehensive understanding on the current research progresses and research demands regarding NPs cycling. [ABSTRACT FROM AUTHOR]

Recalcitrant dissolved organic carbon (RDOC) produced by microbial carbon pumps (MCPs) in the ocean is crucial for carbon sequestration and regulating climate change in the history of Earth. However, the importance of microbes on RDOC formation in terrestrial aquatic systems, such as rivers and lakes, remains to be determined. By integrating metagenomic (MG) and metatranscriptomic (MT) sequencing, we defined the microbial communities and their transcriptional activities in both water and silt of a typical karst river, the Lijiang River, in Southwest China. Betaproteobacteria predominated in water, serving as the most prevalent population remodeling components of dissolved organic carbon (DOC). Binning method recovered 45 metagenome-assembled genomes (MAGs) from water and silt. Functional annotation of MAGs showed Proteobacteria was less versatile in degrading complex carbon, though cellulose and chitin utilization genes were widespread in this phylum, whereas Bacteroidetes had high potential for the utilization of macro-molecular organic carbon. Metabolic remodeling revealed that increased shared metabolites within the bacterial community are associated with increased concentration of DOC, highlighting the significance of microbial cooperation during producing and remodeling of carbon components. Beta-oxidation, leucine degradation, and mevalonate (MVA) modules were significantly positively correlated with the concentration of RDOC. Blockage of the leucine degradation pathway in Limnohabitans and UBA4660-related MAGs were associated with decreased RDOC in the karst river, while the Fluviicola-related MAG containing a complete leucine degradation pathway was positively correlated with RDOC concentration. Collectively, our study revealed the linkage between bacteria metabolic processes and carbon sequestration. This provided novel insights into the microbial roles in karst-rivers carbon sink. [ABSTRACT FROM AUTHOR]

To understand how microbiota influence plant populations in nature, it is important to examine the biogeographic distribution of plant-associated microbiomes and the underlying mechanisms. However, we currently lack a fundamental understanding of the biogeography of plant microbiomes across populations and the environmental and host genetic factors that shape their distribution. Leveraging the broad distribution and extensive genetic variation in duckweeds (the Lemna species complex), we identified key factors that governed plant microbiome diversity and compositional variation geographically. In line with the microbial biogeography of free-living microbiomes, we observed higher bacterial richness in temperate regions relative to lower latitudes in duckweed microbiomes (with 10% higher in temperate populations). Our analyses revealed that higher temperature and sodium concentration in aquatic environments showed a negative impact on duckweed bacterial richness, whereas temperature, precipitation, pH, and concentrations of phosphorus and calcium, along with duckweed genetic variation, influenced the biogeographic variation of duckweed bacterial community composition. Analyses of plant microbiome assembly processes further revealed that niche-based selection played an important role (26%) in driving the biogeographic variation of duckweed bacterial communities, alongside the contributions of dispersal limitation (33%) and drift (39%). These findings add significantly to our understanding of host-associated microbial biogeography and provide important insights for predicting plant microbiome vulnerability and resilience under changing climates and intensifying anthropogenic activities. [ABSTRACT FROM AUTHOR]

The polymer flocculants applied to mineral tailings suspensions to aggregate fine particles and thereby enhance solid-liquid separation are also used in a range of other industrial applications. As a consequence, their synthesis, degradation and general solution properties have been extensively reviewed. The polymer's state in solution can vary substantially, and given flocculation activity is closely related to this property, it is surprising there is no systematic review of the many factors at play in maximising flocculant solution activity in tailings applications. At the simplest level these factors influence applied dosages and thereby reagent consumption, but sub-optimal activity can impose performance limits on solid-liquid separation unit operations, with potential adverse effects on downstream tailings properties and both the volume and quality of returned process water. All aspects impacting upon likely polymer flocculant activity are considered, including physical forms, stock solution preparation (dissolution and ageing), water chemistry, mechanical forces in mixing and transport, dilution prior to dosing, temperature effects and dosing locations. Special attention is given to insights gained from studies on industrial tailings suspensions, noting how these may vary due to different operational priorities and conditions. Finally, potential opportunities for research that could contribute to more effective flocculant utilization are discussed. [Display omitted] • Polymer flocculants aggregate fine particles within mineral tailings suspensions. • Aggregation is essential to achieve high throughputs from solid-liquid separation. • Flocculant activity is sensitive to solution make-up, handling and dosing conditions. • Studies on flocculant activity and the factors affecting it are critically reviewed. • Practical strategies to maximise flocculant solution activity are outlined. [ABSTRACT FROM AUTHOR]

Hawaiʻi is home to ʻoʻopu nākea (Awaous stamineus), a culturally significant, endemic, goby that exhibits an amphidromous life cycle characterized by a marine larval stage followed by post‐larval recruitment to streams, where they live to become reproductive adults. However, it was recently suggested that their migration to the ocean might not be obligatory, as originally thought. Despite their importance in Hawaiian traditions and the ecology of Hawaiian freshwater ecosystems, we still lack a full understanding of their migratory patterns and life history due to the difficulties in determining the environmental migratory cues that set the timing and location of their migratory paths. This study examined environmental factors, such as mean annual rainfall, streamflow, and water chemistry, to determine if they play a role in whether A. stamineus spend their larval period in the ocean or their entire life cycle in freshwater streams. We sampled A. stamineus (n = 90) from three streams (Kahana, Kahaluʻu, and Waimānalo) on the island of Oʻahu, Hawaiʻi that represented the range of hydroclimatic gradient in wet‐habitat conditions on the windward side of the island and characterized their migratory pattern using elemental analysis of sagittae, the largest pair of otoliths (calcareous ear structures). Based on otolith strontium:calcium and barium:calcium ratios, we determined if individuals spent their larval period in the ocean or the stream. We found that 100% of individuals displayed clear evidence of marine residence during their larval phase, regardless of the environmental factors the fish experienced. This study highlights the necessity of stream–ocean connectivity for the survival of A. stamineus and emphasizes the importance of stream‐mouth conservation and management as it is a critical transition zone in stream–ocean–stream migratory pathways. [ABSTRACT FROM AUTHOR]

Seasonal changes in light and physicochemical conditions have strong impacts on cyanobacteria, but how they affect community structure, metabolism, and biogeochemistry of cyanobacterial mats remains unclear. Light may be particularly influential for cyanobacterial mats exposed to sulphide by altering the balance of oxygenic photosynthesis and sulphide‐driven anoxygenic photosynthesis. We studied temporal shifts in irradiance, water chemistry, and community structure and function of microbial mats in the Middle Island Sinkhole (MIS), where anoxic and sulphate‐rich groundwater provides habitat for cyanobacteria that conduct both oxygenic and anoxygenic photosynthesis. Seasonal changes in light and groundwater chemistry were accompanied by shifts in bacterial community composition, with a succession of dominant cyanobacteria from Phormidium to Planktothrix, and an increase in diatoms, sulphur‐oxidizing bacteria, and sulphate‐reducing bacteria from summer to autumn. Differential abundance of cyanobacterial light‐harvesting proteins likely reflects a physiological response of cyanobacteria to light level. Beggiatoa sulphur oxidation proteins were more abundant in autumn. Correlated abundances of taxa through time suggest interactions between sulphur oxidizers and sulphate reducers, sulphate reducers and heterotrophs, and cyanobacteria and heterotrophs. These results support the conclusion that seasonal change, including light availability, has a strong influence on community composition and biogeochemical cycling of sulphur and O2 in cyanobacterial mats. [ABSTRACT FROM AUTHOR]

Here, we present a dataset of a decade-long monitoring project of Lake Żabińskie, a hardwater eutrophic lake in northeast Poland. The lake contains annually laminated (varved) sediments that form a unique archive of past environmental variability. Regular measurements of the lake water physical and chemical characteristics were done using a multiparameter sonde and a set of temperature sensors deployed in the water column. Seasonal variability in sediment fluxes was documented by a sediment trap. Field sampling provided information about the hydrochemistry of incoming streams and of the lake outflow. The overall monitoring program was designed to assess relationships among meteorological conditions, limnological processes, and modern sedimentation and to answer the question of whether meteorological and limnological phenomena can be precisely tracked with varves. However, this dataset can also be used for modeling physical and biogeochemical processes in lakes. The dataset is archived at 10.34808/w8w7-9x34 (Tylmann et al., 2023). [ABSTRACT FROM AUTHOR]

Towards a better understanding of factors controlling carbon (C) exchange between inland waters and atmosphere, we addressed the inorganic carbon cycle in semiarid lakes of Central Eurasia, subjected to the strong impact of on-going climate change. As such, we assessed the hydrochemical variability and quantified its control on the formation of authigenic carbonate minerals, occurring within the upper layer of sediments in 43 semiarid lakes located in the southwest of Western Siberia (Central Eurasia). Based on measurements of pH, total dissolved solids (TDS), cationic and anionic composition, dissolved organic and inorganic C, as well as textural and mineralogical characterization of bottom sediments using X-ray diffraction and scanning electron microscopy, we demonstrate that lake water pH and TDS are primarily controlled by both the lithological and climatic context of the lake watershed. We have not revealed any direct relationships between lake morphology and water chemistry. The most common authigenic carbonates scavenging atmospheric CO2 in the form of insoluble minerals in lake sediments were calcite, aragonite, Mg-calcite, dolomite and hydromagnesite. The calcite was the most common component, aragonite mainly appears in lakes with sediments enriched in gastropod shells or artemia cysts, while hydromagnesite was most common in lakes with high Mg/Ca molar ratios, as well as at high DIC concentrations. The relationships between mineral formation and water chemistry established in this study can be generalized to a wide suite of arid and semiarid lakes in order to characterize the current status of the inorganic C cycle and predict its possible modification under on-going climate warming such as a rise water temperature and a change in hydrological connectivity, primary productivity and nutrient regime. [ABSTRACT FROM AUTHOR]

This research aims to examine the impact of sodium silicate (SS) on the mechanical and microstructural properties of cemented paste tailings or cemented paste backfill (CPB), a cementitious construction material extensively used in underground mining operations. The study involved various compositions and curing conditions of SS-CPB samples, and their uniaxial compressive strength (UCS), stress–strain behavior, microstructure, and modulus of elasticity were evaluated by conducting mechanical (UCS) and microstructural (DT/DTG, MIP) tests, as well as monitoring experiments. Findings indicate that SS improves the mechanical strength of CPB and enhances its microstructure. The development of UCS is affected by SS dosage, curing time, water chemistry, curing temperature, and curing stress. Higher SS dosage, curing time, temperature, and stress lead to higher UCS, while sulfates decrease UCS. SS also increases CPB's resistance to sulfate attack, and field curing temperature improves the binder hydration enhancement induced by SS. The presence of SS affects the stress–strain properties of CPB, including the shape of the stress–strain curve, maximum stress and strain, and modulus of elasticity. The modulus of elasticity of CPB with SS is higher than that without SS under field thermal curing conditions. Moreover, UCS and the modulus of elasticity have a linear relationship in SS-CPB, regardless of SS content. A relationship is proposed to estimate the modulus of elasticity of SS-CPB from its UCS. The study has significant practical implications for the cost-effective design of mine CPB structures and for improving underground mine work safety and productivity. [ABSTRACT FROM AUTHOR]

Simple Summary: Biodiversity is measured differently depending on the spatial scale of the study. Beta (β)-diversity, for example, is a calculated measurement that addresses changes in diversity across different assemblages in a specific region. Studies of β-diversity often address changes in diversity across gradients of environmental conditions and distance among sites. However, β-diversity of stream insects can be difficult to measure due to their hyper-diversity and challenging taxonomy. Our study investigated the association of β-diversity with habitat conditions and distance among these habitats for insects found in the coastal streams of Alabama, USA. Additionally, we looked for potential influences caused by seasonality (fall and summer) and the level of taxonomic identification (genus, species). Regardless of season, stream conditions were highly correlated with β-diversity. More specifically, stream size and water chemistry showed the highest associations with β-diversity. Changes in β-diversity were largely driven by species replacement (turnover) rather than species loss (nestedness). The taxonomic resolution had minimal effects on the calculations of β-diversity across environmental conditions. Distance among stream sites was never correlated with β-diversity. As we continue to face global insect declines, our study provides valuable insight into the patterns that drive changes in diversity across environmental gradients. β-diversity is often measured over both spatial and temporal gradients of elevation, latitude, and environmental conditions. It is of particular interest to ecologists, as it provides opportunities to test and infer potential causal mechanisms determining local species assemblages. However, studies of invertebrate β-diversity, especially aquatic insects, have lagged far behind other biota. Using partial Mantel tests, we explored the associations between β-diversity of insects found in the coastal streams of Alabama, USA, and stream conditions and distances among sites. β-diversity was expressed using the Sørensen index, βSor, stream conditions were expressed as principal components (PCs), and distances as Euclidean distances (km) among sites. We also investigated the impact of seasonality (fall, summer) and taxonomic resolution (genus, species) on βSor. Regardless of season, βSor was significantly correlated (p < 0.01; r > 0.44) with stream conditions (stream size and water chemistry), while taxonomic resolution had minimal effect on associations between βSor and stream conditions. Distance was never correlated with changes in βSor (p > 0.05). We extended the use of the Sørensen pair-wise index to a multiple-site dissimilarity, βMult, which was partitioned into patterns of spatial turnover (βTurn) and nestedness (βNest). Changes in βMult were driven mostly by turnover rather than nestedness. [ABSTRACT FROM AUTHOR]

Nitrate (NO3−) pollution in karst areas has been widely discussed, which affects human health and the ecological environment. To investigate nitrate sources and their perturbations on cave hydrogeochemistry in karst cave systems, this study was conducted in Mahuang Cave, a karst cave in Southwest China, to assess the impact of human activities on the karst carbon cycle and the environment. The results show that (1) the variations of the water-soluble ions in Mahuang Cave are mainly controlled by carbonate weathering, and the cave water chemistry is characterized as the HCO3–Ca–Mg and HCO3–SO4–Ca–Mg types. (2) The dual isotopes and stable isotope Bayesian mixing model (SIAR) show that chemical fertilizers (41.5%) and soil nitrogen (33.75%) are the main nitrate sources in the cave water bodies, followed by manure and sewage (17.25%) and atmospheric precipitation (7.5%). (3) The significant enrichment of dissolved inorganic carbon isotope (δ13CDIC) in Mahuang Cave reveals that nitric acid produced by nitrification accelerates carbonate weathering in Mahuang Cave, and the carbon source effect of the carbon cycle in the cave is enhanced. Consequently, the response of cave drips and sediments to external environments is disturbed. [ABSTRACT FROM AUTHOR]

Gas-hydrate saturation and porosity are the most crucial reservoir parameters for gashydrate resource assessment. Numerous academics have put forward elastic and electrical petrophysical models for calculating the saturation and porosity of gas-hydrate. However, owing to the limitations of a single petrophysical model, the estimation of gas-hydrate saturation and porosity using single elastic or electrical measurement data appears to be inconsistent and uncertain. In this study, the sonic wave velocity, density and resistivity well log data are combined with a Bayesian linear inversion method for the simultaneous estimation of gas-hydrate saturation and porosity. The sonic wave velocity, density and resistivity data of the Shenhu area in the South China Sea are used to estimate the gas-hydrate saturation and porosity. To validate the accuracy of this method, the estimation results are compared with the saturation obtained from pore water chemistry and porosity obtained from density logs. The well log data examples show that the joint estimation method not only provides a rapid estimation of the gas-hydrate reservoir parameters but also improves the accuracy of results and determines their uncertainty. [ABSTRACT FROM AUTHOR]

Geochemical investigations carried out on thermal waters over the Erzin-Hatay area allowed the collection of a suite of 9 samples from natural springs and one well characterized by outlet temperatures in the range from 19.6 to 31.5 °C. All of the springs have slightly acidic pH (in the range of 6) but one sample was marked by a pH value >11 as a consequence of serpentinization processes. The water chemistry denotes water/rock interactions with either magmatic or carbonatic rocks in a water reservoir equilibrated at temperatures estimated to be in the range of 58-162 °C. The stable isotope composition of the collected waters, in terms of dD and d18O, denotes a recharge from local meteoric waters. The dissolved gases denote the contribution of no atmospheric components. CO2 is the dominant dissolved component for most of the sample, while methane is the major component for the thermal water involved in serpentinization. Besides the main components CO2 and CH4, the dissolved gases show significant concentrations of He, H2, and CO. The isotopic composition of helium shows ³He/4He ratios well above that of Air Saturated Waters (ASW = 1.39 x 10-6) clearly indicating a significant contribution of 3He of mantle origin. Taking into account the location of some sampling sites nearby the Düziçiİskenderun Active Fault Zone and the associated mantle helium contribution, we propose that fluids/faults relationships have to be considered as responsible for the feeding of deep-originated fluids to the shallow groundwater. As mantle-derived fluids are also carriers of thermal energy, the collected results strongly suggest improving the knowledge of the study area, where hydrological and geochemical considerations coupled with the tectonic setting of the area should focus on the geothermal potential of the circulating waters. [ABSTRACT FROM AUTHOR]

Türkiye is located in the Mediterranean sector of the Alpine--Himalayan tectonic belt and is among the foremost seven countries in the world having an abundance of geothermal resources. The Central Anatolian Crystalline Complex (CACC) is one of the most important geothermal regions in Türkiye. This study aims to evaluate the geothermal system of CACC using the geological, structural, and hydrogeochemical properties that were obtained from previous studies. The present study investigated and evaluated the hydrogeochemical and isotopic properties of 762 water samples belonging to 45 different localities from 41 scientific studies. The result shows that CACC has different heat sources and different hydrogeochemical processes. Major element chemistry of the water reveals that the geothermal fluids are mostly of the Ca - Mg - HCO3, Na - Cl - HCO3, and Ca-Cl water types. Silica geothermometers suggest that the reservoir temperature ranges from 48 to 180 °C. Based on the δ18O - δD relationship, water samples have a high-altitude meteoric origin. Stable isotopic data indicate that the geothermal fluids are formed by local recharge and deep circulation of meteoric waters. [ABSTRACT FROM AUTHOR]

Unionid mussel populations have declined in many environments, particularly those that were altered by human activities such as dam construction and removal. The Fort Covington Dam blocked the Salmon River in northern New York upriver of its confluence with a smaller tributary, the Little Salmon River. This dam was removed in 2009. My study compared the mean ranked density of mussels in both rivers for the pre‐removal period (2005–2008) to the post‐removal period (2009–2012) with special attention to Lampsilis cariosa and Margaritifera margaritifera. Systematic sampling was used at six riffles and double sampling at four glides divided between the Salmon and Little Salmon rivers from 2005 through 2012. The Little Salmon River served as a control. Mean ranked adult mussel density was not significantly different between the two rivers in the pre‐removal period but was significantly greater in the Little Salmon River after dam removal. Living mussels of 13 species were collected dominated by Elliptio complanata. Dam removal did not affect sediment sorting, porosity, water chemistry, or mussel species distribution. Rapid dewatering of the reservoir led to stranding and death of mussels in the reservoir and in the adjacent ponds. Increased water velocity, exacerbated by rain, mobilized sediment that buried a potentially large mussel bed downstream of the dam where Lampsilis cardium and L. cariosa were abundant, which showed little recovery by 2013. [ABSTRACT FROM AUTHOR]

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Permafrost regions are under particular pressure from climate change resulting in widespread landscape changes, which impact also freshwater chemistry. We investigated a snapshot of hydrochemistry in various freshwater environments in the lower Kolyma river basin (North‐East Siberia, continuous permafrost zone) to explore the mobility of metals, metalloids and non‐metals resulting from permafrost thaw. Particular attention was focused on heavy metals as contaminants potentially released from the secondary source in the permafrozen Yedoma complex. Permafrost creeks represented the Mg‐Ca‐Na‐HCO3‐Cl‐SO4 ionic water type (with mineralisation in the range 600–800 mg L−1), while permafrost ice and thermokarst lake waters were the HCO3‐Ca‐Mg type. Multiple heavy metals (As, Cu, Co, Mn and Ni) showed much higher dissolved phase concentrations in permafrost creeks and ice than in Kolyma and its tributaries, and only in the permafrost samples and one Kolyma tributary we have detected dissolved Ti. In thermokarst lakes, several metal and metalloid dissolved concentrations increased with water depth (Fe, Mn, Ni and Zn – in both lakes; Al, Cu, K, Sb, Sr and Pb in either lake), reaching 1370 μg L−1 Cu, 4610 μg L−1 Mn, and 687 μg L−1 Zn in the bottom water layers. Permafrost‐related waters were also enriched in dissolved phosphorus (up to 512 μg L−1 in Yedoma‐fed creeks). The impact of permafrost thaw on river and lake water chemistry is a complex problem which needs to be considered both in the context of legacy permafrost shrinkage and the interference of the deepening active layer with newly deposited anthropogenic contaminants. [ABSTRACT FROM AUTHOR]

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Three wetland‐shallow lakes were studied with the aim of analysing the processes and factors that control hydrochemistry and evaporite deposits in them in basins of the Pampean Plain, Argentina. In this sense, water balances and analysis of the water content of the lakes with normalized water difference index were made, and geologic‐geomorphological characteristics and groundwater flows were defined. Groundwater, surface water and evaporite samples were taken, along with sediment samples from wetland‐shallow lakes and surroundings. In situ pH, electrical conductivity and temperature, and laboratory chemical determinations of major ions of the water were measured. x‐ray diffraction (XRD) and scanning electron microscope (SEM)‐energy dispersive spectroscopy (EDS) analyses of evaporite and sediment samples were carried out. The results obtained allow the identification of two different systems. One of them is represented by Leubucó wetland‐lake basin, which is topographically higher and smaller than the other system, with Na‐HCO3 and Na‐Cl/SO4 groundwater inflows, with high concentrations of Ca2+ and Mg2+. In periods of high evaporation, the regional water table drops, and due to its topographic position, the lake dries. These determine the formation of thick layers of halite associated with magnesium salts on surface, and gypsum layers interbedded with clastic sediments. The other system involves de la Sal and Chasilauquen wetland‐lake basins, which have larger extensions. They receive Na‐HCO3 and Na‐Cl/SO4 groundwater inflow, but with low Mg2+ and Ca2+. Their lower topographic position determines that even during deficit periods, the water table intercepts the lakes surface and therefore, lakes have a shallow surface water level almost all the year, which is hypersaline, Na‐Cl type. These systems only have thin evaporite crusts, composed of halite and thenardite at the edges of the lakes, and the formation of Ca‐Mg sulfates is not observed. It is concluded that topographic position, basins size, geology, groundwater inflow and evaporation are the main processes and factors controlling hydrochemistry and evaporitic deposits. [ABSTRACT FROM AUTHOR]

Climate change and permafrost thaw may impact the mobilization of terrestrial dissolved organic carbon (DOC), mercury (Hg), and neurotoxic methylmercury (MeHg) into aquatic ecosystems; thus, understanding processes that control analyte export in northern catchments is needed. We monitored water chemistry for 3 years (2019–2021) at a peatland catchment (Scotty Creek) and a mixed catchment (Smith Creek) in the Dehcho (Northwest Territories), within the discontinuous permafrost zone of boreal western Canada. The peatland catchment had higher DOC and dissolved MeHg, but lower total Hg concentrations (mean ± standard deviation; 19 ± 2.6 mg DOC L−1; 0.08 ± 0.04 ng DMeHg L−1; 1.1 ± 0.3 ng THg L−1) than the mixed catchment (12 ± 4.4 mg DOC L−1; 0.05 ± 0.01 ng DMeHg L−1; 3.1 ± 2.2 ng THg L−1). Analyte concentrations increased with discharge at the mixed catchment, suggesting transport limitation and the flushing of near‐surface, organic‐rich flow paths during wet periods. In contrast, analyte concentrations in the peatland catchment were not primarily associated with discharge. MeHg concentrations, MeHg:THg, and MeHg:DOC increased with water temperature, suggesting enhanced Hg methylation during warmer periods. Mean open water season DOC and total MeHg yields were greater and more variable from the peatland than the mixed catchment (1.1–6.6 vs. 1.4–2.4 g DOC m−2; 5.2–36 vs. 6.1–10 ng MeHg m−2). Crucial storage thresholds controlling runoff generation likely drove greater inter‐annual variability in analyte yields from the peatland catchment. Our results suggest climate change may influence the production and transport of MeHg from boreal‐Arctic catchments as temperatures increase, peatlands thaw, and runoff generation is altered. Plain Language Summary: Boreal rivers deliver dissolved organic carbon (DOC), mercury (Hg), and its neurotoxic form, methylmercury (MeHg), from contributing landscapes to downstream waters. In northern regions, thawing permafrost (i.e., perennially frozen ground) in peatland environments may release Hg, MeHg, and DOC from soils to rivers. Over 3 years, we measured the concentrations of water chemistry in two boreal creeks with differing contributing landscapes in the discontinuous permafrost region of the Dehcho (Northwest Territories, Canada). Our results showed different patterns in analyte concentrations versus yields (i.e., annual analyte mass delivered per unit area) between the sites. At the peatland‐dominated Scotty Creek, concentrations of MeHg and DOC were consistently high and not primarily controlled by discharge. Still, runoff and analyte yields varied annually as peatlands stored water in a dry year and discharged water in wet years. At Smith Creek, with a mixed landscape of mountains, peatlands, and forests, concentrations of DOC and Hg increased during high‐flow events as runoff contributions from peatlands increased. Over the monitoring period, analyte yields at the mixed catchment varied less due to consistent groundwater inputs and runoff generation from steeper slopes. Changing runoff due to climate change and permafrost thaw will likely alter analyte yields in the region. Key Points: Comparison of mercury, methylmercury, and dissolved organic carbon concentrations and yields for a peatland and a mixed‐landscape catchmentProduction of methylmercury in the peatland catchment was temperature‐dependent, and yields were limited by runoff generation thresholdsAnalyte concentrations in the mixed catchment increased with discharge, and had lower inter‐annual variability in analyte yields [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Naturalium Universitatis Pekinensis is the property of Editorial Office of Acta Scientiarum Naturalium Universitatis Pekinensis and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Stream macroinvertebrate assemblages are shaped by natural and human‐related factors that operate through complex hierarchical pathways. Quantifying these relationships can provide additional insights into stream ecological assessment. We applied a structural equation modeling framework to evaluate hypothesized pathways by which watershed, riparian, and in‐stream factors affect benthic macroinvertebrate condition in the Western Mountains (WMT) and Xeric (XER) ecoregions in the United States. We developed a conceptual model grounded in theory, empirical evidence, and expert opinion to evaluate the following hypotheses: (1) macroinvertebrate assemblages are primarily driven by proximal, in‐stream factors (e.g., water quality and physical habitat); (2) anthropogenic land uses affect macroinvertebrates indirectly by altering in‐stream characteristics; and (3) riparian vegetation cover attenuates land use effects. We tested our model separately on three measures of benthic macroinvertebrate assemblage condition: ratio of observed‐to‐expected taxonomic richness (O/E); a multimetric index (MMI); and richness of Ephemeroptera, Plecoptera, and Trichoptera taxa (EPT). In the WMT, site‐level riparian cover, in‐stream physical habitat (relative bed stability), and water chemistry (total nitrogen) were the top three predictors of macroinvertebrate assemblages, each having over two times the magnitude of effect on macroinvertebrates compared with watershed‐level predictors. In the arid XER, annual precipitation and stream flow characteristics were top predictors of macroinvertebrate assemblages and had similar magnitudes of effect as in‐stream water chemistry. Path analyses revealed that land use activities in the watershed and at the stream site degraded macroinvertebrate assemblages indirectly by altering relative bed stability, water quality, and riparian cover/complexity. Increased riparian cover was associated with greater macroinvertebrate condition by reducing land use impacts on stream flow, streambed substrate, and water quality, but the pathways differed among ecoregions. In the WMT, site‐level riparian cover affected macroinvertebrate assemblages partly through indirect pathways associated with greater streambed stability and reduced total nitrogen concentrations. In contrast, in the XER, watershed‐level riparian cover affected macroinvertebrate assemblages through greater specific stream power. Identifying the relative effects of and pathways by which natural and anthropogenic factors affect macroinvertebrates can serve as a framework for prioritizing management and conservation efforts. [ABSTRACT FROM AUTHOR]

The ExoMars Trace Gas Orbiter instruments, Nadir and Occultation for Mars Discovery and Atmospheric Chemistry Suite have provided vertical profiles of H2O and HDO mixing ratios in the presence and absence of Global Dust Storm 2018. These observations are carried out in the lower atmosphere at SZA ∼ 71° of northern mid latitude (∼55°N, 130°E). Using NOMAD observations, we developed chemical models 1 and 2 for dust and non‐dust storm conditions, respectively. The production/loss rates of H2O, HDO and D2O and the densities of water, nitrogenated and deuterated cluster ions (H2O+, D2O+, HDO+, H+(H2O)n, D+(D2O)n, H+(HDO)n, CO4−, CO3−, CO3−(H2O)n, CO3−(D2O)n, CO3−(HDO)n, NO2−(H2O), NO2−(HDO), and NO2−(D2O) (for n = 1 to 5)) are estimated from these models between 10 and 70 km. We have used two ionization sources: (a) Galactic Cosmic Rays (GCR) and (b) hard X‐ray in both models. The D peak density produced by GCR is lower by a factor of ∼5 than that produced by the hard X‐rays. In model 1, the electron densities were increased by a factor of ∼2–3 than that produced by model 2. The estimated production/loss rates of H2O, HDO, and D2O are also larger by an order of magnitude in model 1 than that estimated by model 2. Plain Language Summary: The chemistry of the lower ionosphere of Mars is very complex because of the rapidly increasing number of ion species at larger masses. It couples ion‐neutral, electron‐neutral, dissociation of positive/negative ions, electron detachment, ion‐ion and ion‐electron recombination processes through various chemical reactions. In this paper we have performed ionospheric modeling and used Nadir and Occultation for Mars Discovery observations as inputs for the model. The chemistry of water, nitrogenated and deuterated cluster ions were studied. The production/loss of H2O, HDO, and D2O are also estimated during Global Dust Storm 2018. One‐dimensional chemical model 1 and 2 have been developed to estimate the densities of these cluster ions in the presence and absence of dust storm respectively. In this modeling, two ionization sources, (a) Galactic Cosmic Rays and (b) hard X‐ray, are used. In model 1 estimated production/loss rates of H2O, HDO, and D2O are increased by an order of magnitude than that estimated by model 2. The estimated densities are also larger in model 1 by a factor of 2–3 than that produced by model 2. There is no measurement of ion/electron density in the lower ionosphere of Mars. In the absence of measurements, predicted results improve our understanding of the ionospheric chemistry of Mars and its environment. Key Points: The densities of water, nitrogenated and deuterated cluster ions in the presence and absence of Global Dust Storm 2018 are estimatedThe Trace Gas Orbiter data (H2O and HDO) are used for the first time in the modeling of the lower ionosphere of MarsThe production and loss rates of H2O, HDO, and D2O are increased by one order of magnitude during the dust storm [ABSTRACT FROM AUTHOR]

Speleothems, particularly stalagmites are extensively used to reconstruct paleoclimatic and paleomonsoon changes by using stable oxygen and carbon isotopes along the growth profile of a stalagmite sample. Trace and rare earth elements (REEs) variations in stalagmites are widely recognized as indicators of past precipitation and local hydrology. The amalgamation of isotopic and trace element proxies in speleothems has been regarded as an important tool to infer past climate and hydro-chemical fluctuations. Current advancements in geochemical techniques have enabled us to generate high-resolution paleo-records of almost all trace and REEs from stalagmites. However, their assessment is dependent on numerous factors that control the formation of a stalagmite. Here we present a geochemical record from a well dated stalagmite (VSPM1) from a cave located in the southern India. The stalagmite grew between 15,610 and 13,160 yr BP as revealed by its StalAge modelled ages from eight U–Th dates. This study demonstrates significant variations in trace and REEs during the last deglacial time interval of 2100 years and suggests variations in drip water chemistry. The relative amount of trace elements in colloidal solutions originating from the soil organics and weathered particles of host dolomitic rock may have altered with climatic changes. It appears that trace and REEs of VSPM1 stalagmite have responded to fluctuations in Indian Summer Monsoon (ISM) intensity during the time interval of this study. [ABSTRACT FROM AUTHOR]

Fine-particle pollution associated with high sulfate and secondary organic aerosol (SOA) contents still occurs in winter, despite considerable reductions in precursor emissions in China. The chemical mechanisms involved are consistently acknowledged to be linked with aerosol water but remain poorly understood. Here, we present findings demonstrating that the synergistic effect of elevated aerosol water content and particles originating from fossil fuel combustion significantly enhanced the rapid formation of sulfate and SOAs under high humidity conditions during winter in northern China. The presence of high aerosol water content promoted the aging process of particles containing elemental carbon (EC) and facilitated the formation of SOAs. Evidence from single particles reveals an increased potential for SOA formation from primary organic aerosols (POAs) originating from fossil fuel combustion, in the presence of increasing aerosol water. Under conditions of relative humidity exceeding 85%, the multiphase oxidation of SO2 by in-particle nitrite/nitrous acid, generated through reactions involving aged EC-containing and iron-rich particles, as well as aqueous-phase formation of hydroxymethanesulfonate (HMS), led to a substantial increase in sulfate production. This study emphasizes the critical role of aerosol water in the aerosol chemistry concerning sulfate and SOAs, highlighting the urgent necessity to mitigate primary emissions from fossil fuel combustion. [ABSTRACT FROM AUTHOR]

Plants emit biogenic volatile organic compounds (BVOCs) in response to changes in environmental conditions (e.g. temperature, radiation, soil moisture). In the large family of BVOCs, isoprene is by far the strongest emitted compound and plays an important role in ozone chemistry, thus affecting both air quality and climate. In turn, climate change may alter isoprene emissions by increasing temperature as well as the occurrence and intensity of severe water stresses that alter plant functioning. The Model of Emissions of Gases and Aerosols from Nature (MEGAN) provides different parameterizations to account for the impact of water stress on isoprene emissions, which essentially reduces emissions in response to the effect of soil moisture deficit on plant productivity. By applying the regional climate–chemistry model RegCM4chem coupled to the Community Land Model CLM4.5 and MEGAN2.1, we thus performed sensitivity simulations to assess the effects of water stress on isoprene emissions and near-surface ozone levels over the Euro-Mediterranean region and across the drier and wetter summers over the 1992–2016 period using two different parameterizations of the impact of water stress implemented in the MEGAN model. Over the Euro-Mediterranean region and across the simulated summers, water stress reduces isoprene emissions on average by nearly 6 %. However, during the warmest and driest selected summers (e.g. 2003, 2010, 2015) and over large isoprene-source areas (e.g. the Balkans), decreases in isoprene emissions range from -20 % to -60 % and co-occur with negative anomalies in precipitation, soil moisture and plant productivity. Sustained decreases in isoprene emissions also occur after prolonged or repeated dry anomalies, as observed for the summers of 2010 and 2012. Although the decrease in isoprene emissions due to water stress may be important, it only reduces near-surface ozone levels by a few percent due to a dominant VOC-limited regime over southern Europe and the Mediterranean Basin. Overall, over the selected analysis region, compared to the old MEGAN parameterization, the new one leads to localized and 25 %–50 % smaller decreases in isoprene emissions and 3 %–8 % smaller reductions in near-surface ozone levels. [ABSTRACT FROM AUTHOR]

Background: Risks of adverse ecological effects of copper (Cu) consider of water quality parameters were not fully understood in China. Here, a national-scale exposure of Cu in Chinese surface water was investigated, and the first report using multiple linear regression approach to predict and correct toxicity data based on water chemistries in China. Risk of Cu was overestimated without considering water quality parameters in the previous studies. Results: Under prevalent water quality conditions of hardness = 150.0 mg/L, pH = 7.8, and dissolved organic carbon (DOC) = 3.0 mg/L, across China, the predicted no effect concentration for total, dissolved Cu was 9.71 μg/L. Based on results of the preliminary risk quotients method, 1.19% (a total of 43 in 3610 sites) were classified as "high risk", only one sixth of the percentage of sites with "high risk" than the proportion predicted when not considering water quality parameters, which was 7.51%. Similar results were obtained by application of both the margin of safety method (0.71% compared to 2.81%) and joint probability curve method (3.34% compared to 16.29%), both of which overestimated risks posed by Cu to aquatic organisms in China. Conclusion: After correcting for bioavailability based on water quality parameters, consider both concentrations and frequencies during ecological risk assessment, regions of China at greatest risk from adverse effects of Cu were the Hai River (Haihe), Huai Rivers (Huaihe) and Chao Lake. These findings provide a comprehensive method for a more accurate assessment of risks of adverse effects of Cu to aquatic life in surface waters. [ABSTRACT FROM AUTHOR]

The aim of this study was to elucidate the contaminant sources and the processes controlling the groundwater quality and risk assessment of heavy metals posed on humans by statistical indices. The groundwater sampling was performed at Bodhjungnagar Industrial Estate, A.D. Nagar, Dukli and Badharghat Industrial Cluster, Tripura, India during pre-monsoon and post-monsoon in the year 2017. A total of 21 water quality parameters (Temp, pH, TDS, Ca, Mg, TH, Na, K, HCO3, Cl, SO4, PO4, NO3, F, Fe, Mn, Pb, Cd, As, Cu, Zn, and Cr) were determined from collected samples. The statistical and graphical methods were employed to assess the suitability of water. The water quality index (WQI) suggested that the majority of the samples are suitable for drinking purpose. The WATEQ4F model was applied to compute the saturation index (SI) of different minerals present in the water samples. Based on Piper plot the dominant water type is Ca-Cl in the study area. The Nemerow integrated pollution index (NIPI) indicates that the groundwaters of both industrial sites have moderately to highly deteriorated water with heavy metals. The hazard index (HI) revealed that amongst the population, chronic health risk was greater for children and considering the seasons, the risk was higher during the pre­monsoon season. [ABSTRACT FROM AUTHOR]

This study examines zooplankton assemblage structure and density from five hypereutrophic urban shallow lakes between cool and hot periods in 2018-2019. We analyzed the variation of zooplankton and their relationship with environmental factors. Samples of zooplankton were collected from shallow lakes in different regions of Thailand. Four groups of zooplankton were identified, of which Rotifera was the most abundant group, followed by Copepoda, Protozoa, and Cladocera. Zooplankton assemblages were influenced by seasons, as indicated by multidimensional scaling analysis. The number of species and density of zooplankton were lower during the cool period than during the hot period. The increased density of zooplankton in the hot period may have been due to increased phytoplankton density as food sources. Pearson's correlation coefficient revealed that Rotifera and Copepoda positively correlated with the temperature and pH, and Rotifera was negatively correlated with total phosphorus; a negative correlation was also observed between Protozoa and dissolved oxygen. The microcystin content tended to have a negative impact on specific small species such as Protozoa (Coleps sp.). Information from this research is important for further study involving factors affecting the size structure of zooplankton communities, especially large-bodied species in tropical regions. [ABSTRACT FROM AUTHOR]

Global urbanization of waterways over the past millennium has influenced microbial communities in these aquatic ecosystems. Increased nutrient inputs have turned most urban waters into net sources of the greenhouse gases carbon dioxide (CO2) and methane (CH4). Here, canal walls of five Dutch cities were studied for their biofilm CH4 oxidation potential, alongside field observations of water chemistry, and CO2 and CH4 emissions. Three cities showed canal wall biofilms with relatively high biological CH4 oxidation potential up to 0.48 mmol gDW−1 d−1, whereas the other two cities showed no oxidation potential. Salinity was identified as the main driver of biofilm bacterial community composition. Crenothrix and Methyloglobulus methanotrophs were observed in CH4-oxidizing biofilms. We show that microbial oxidation in canal biofilms is widespread and is likely driven by the same taxa found across cities with distinctly different canal water chemistry. The oxidation potential of the biofilms was not correlated with the amount of CH4 emitted but was related to the presence or absence of methanotrophs in the biofilms. This was controlled by whether there was enough CH4 present to sustain a methanotrophic community. These results demonstrate that canal wall biofilms can directly contribute to the mitigation of greenhouse gases from urban canals. [ABSTRACT FROM AUTHOR]

Cold-temperate headwaters of Patagonia are interdigitated in a narrow sector of the Andes mountains devoid of anthropogenic impacts and thus are suitable systems to evaluate the climate and landscape controls on terrestrial-aquatic fluxes. In this investigation we focused on evaluating dissolved organic matter (DOM) and nutrient dynamics in a stream born in a mountain lake draining a steep forested catchment, a typical configuration of Andean-Patagonian headwaters. Stream water chemistry was studied throughout the hydrologic year and at different sites along the altitudinal drainage gradient. The analyses showed extremely low nutrient and dissolved organic carbon (DOC) concentrations and low primary production within the ranges of ultraoligotrophy. Pulses of terrestrial DOM and nutrient inputs were detected during rainfall events and in snowmelt periods, shifting distinctively the nutrients as well as the DOC concentration and quality from baseflow conditions. Stream DOM pools, characterized through optical methods, showed the prevalence of terrigenous humic components (C1 and C2) and a small contribution of a non-humic component (C3), with rainfall runoff increasing the C2 and snowfall enhancing the C3. Stream sites at higher elevation were influenced by the upstream lake showing signatures of phytoplankton production and degradation in their DOM pools, whereas downstream points displayed higher terrestrial prints. The results presented here contribute to understanding carbon and nutrient dynamics in cold-temperate pristine freshwaters of the Southern Hemisphere, which are underrepresented in global studies and differ substantially from temperate systems of the Northern Hemisphere in terms of climate and anthropogenic pressures. [ABSTRACT FROM AUTHOR]

Shallow littoral areas in lakes are productive and highly diverse ecotonal zones, providing habitats for both invertebrate and vertebrate species. We developed a Bayesian modeling framework to elucidate the relationships between environmental drivers (lake typology, habitat, water chemistry, and latitude) and taxon richness, abundance, as well as the content of polyunsaturated fatty acids (PUFAs) in littoral macroinvertebrate communities in 95 boreal lakes. PUFAs, particularly arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), are critical micronutrients to maintain normal physiological functions in consumers. Lake typology was a significant predictor for PUFA content in the invertebrate assemblages, which was connected to taxon richness and/or abundance. Benthic communities in large humus-poor or nutrient-rich lakes displayed higher abundance, taxon richness, and more PUFA-rich taxa, whereas those in medium- and large-sized humic (color 30–90 mg Pt/L) and humus-rich lakes (color >90 mg Pt/L) were characterized by decreased abundance and subsequently low PUFA content. The abundance, taxon richness, and nutritional quality of the communities were also strongly related to latitude. Lakes with lower pH were characterized by lower benthic invertebrate diversity and low frequency of taxa with high somatic EPA and DHA content. The complexity of littoral habitats dominated by various macrophyte assemblages creates an environment that favors higher benthic abundance and increased presence of taxonomic groups with high PUFA content. Nutritional quality of benthic invertebrates for upper trophic levels can be modulated by a complex interplay between external stressors and abiotic factors that typically shape the structure of littoral benthic communities. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition has increased substantially since the second half of the 20th century due to human activities. This increase of reactive N into the biosphere has major implications for ecosystem functioning, including primary production, soil and water chemistry and producer community structure and diversity. Increased N deposition is also linked to the decline of insects observed over recent decades. However, we currently lack a mechanistic understanding of the effects of high N deposition on individual fitness, species richness and community structure of both invertebrate and vertebrate consumers. Here, we review the effects of N deposition on producer–consumer interactions, focusing on five existing ecological frameworks: C:N:P ecological stoichiometry, trace element ecological stoichiometry, nutritional geometry, essential micronutrients and allelochemicals. We link reported N deposition‐mediated changes in producer quality to life‐history strategies and traits of consumers, to gain a mechanistic understanding of the direction of response in consumers. We conclude that high N deposition influences producer quality via eutrophication and acidification pathways. This makes oligotrophic poorly buffered ecosystems most vulnerable to significant changes in producer quality. Changes in producer quality between the reviewed frameworks are often interlinked, complicating predictions of the effects of high N deposition on producer quality. The degree and direction of fitness responses of consumers to changes in producer quality varies among species but can be explained by differences in life‐history traits and strategies, particularly those affecting species nutrient intake regulation, mobility, relative growth rate, host‐plant specialisation, ontogeny and physiology. To increase our understanding of the effects of N deposition on these complex mechanisms, the inclusion of life‐history traits of consumer species in future study designs is pivotal. Based on the reviewed literature, we formulate five hypotheses on the mechanisms underlying the effects of high N deposition on consumers, by linking effects of nutritional ecological frameworks to life‐history strategies. Importantly, we expect that N‐deposition‐mediated changes in producer quality will result in a net decrease in consumer community as well as functional diversity. Moreover, we anticipate an increased risk of outbreak events of a small subset of generalist species, with concomitant declines in a multitude of specialist species. Overall, linking ecological frameworks with consumer life‐history strategies provides a mechanistic understanding of the impacts of high N deposition on producer–consumer interactions, which can inform management towards more effective mitigation strategies. [ABSTRACT FROM AUTHOR]

Determining drivers of community assembly is central to ecology, and patchily distributed temporary habitats offer an ideal system to study the roles of ecological and evolutionary processes in structuring communities over different spatial scales. We studied functionally diverse arthropod communities in 32 freshwater rock pools on 3 plateaus in the Western Ghats biodiversity hotspot, sampling them throughout their hydroperiod (2–7 months). Using the Hierarchical Modeling of Species Communities approach, we assessed (a) the influence of local (water chemistry, habitat complexity at the pool level) and regional (seasonality in temperature and precipitation at the plateau level) scale abiotic covariates in shaping species' occurrence, (b) the influence of species traits (dispersal/reproductive mode, body size, feeding guild) and phylogenetic relationships on species response to abiotic covariates, and (c) the strength of biotic filtering in the communities. Environmental filtering was the dominant driver of community structure, where the pool‐level covariates (mainly hydroperiod and water chemistry), explained greater variation (56.3%) in species occurrences rather than plateau‐level covariates, that is, climatic seasonality (33.7%). Spatial factors explained only 11% of the variation in species occurrences. The selected traits explained 22% variation in species' responses, with body size responding to the abiotic covariates at both spatial scales. Closely related taxa exhibited shared responses to the abiotic covariates. Only a few residual associations were observed, all among passive dispersers, indicating a low contribution of biotic filtering to community structure. Our results highlight the importance of habitat‐level factors and the key role of evolutionary processes in shaping diversity in this vulnerable landscape characterized by its seasonality. [ABSTRACT FROM AUTHOR]

Objective: Silver Chub Macrhybopsis storeriana, a predominately riverine species throughout its native range, exists within Lake Erie as the only known lake population. Its population declined in the 1950s and never fully recovered. Canada has listed Silver Chub in the Great Lakes–St. Lawrence River as endangered and has initiated a recovery plan that recognized the identification of spawning areas as a critical component to inform Silver Chub's recovery potential. Methods: We investigated potential spawning locations of Silver Chub using capture records, otolith microchemistry, and daily age analysis. Lapillus otolith Sr:Ca ratios from 27 age‐0 Silver Chub were used to identify potential spawning areas. Daily ages estimated from lapilli were used to calculate hatch dates, which then were compared with capture data of adults and river flows to further inform potential spawning areas. Result: The Detroit River (and its nearshore area) was all but ruled out as a potential spawning location. The Maumee, Portage, and Sandusky rivers or their nearshore areas were all possible spawning locations. Projected hatch dates spanned the end of May through the end of June and occurred across a wide range of flows, although some peaks in hatch dates corresponded to flow peaks, indicating recruitment is potentially enhanced by high flows. Conclusion: Silver Chub spawning period and hypothesized spawning rivers or lacustuaries overlap those of invasive Grass Carp Ctenopharyngodon idella, creating a need to jointly consider Grass Carp control efforts with conservation of Silver Chub when assessing management alternatives. Further research on spawning guild and the use of rivers themselves or nearshore areas influenced by rivers as spawning areas are required to maximize potential for conservation and recovery of Silver Chub. Impact statementConserving the Silver Chub is vital; it's an indicator of water quality, a food source for aquatic organisms, and preserves biodiversity. Identifying both locations and mode of spawning enhances the conservation of biodiversity in fish communities, ensuring ecosystem stability. [ABSTRACT FROM AUTHOR]

Comparing to the ostracod studies on the other islands in the world, studies on the ostracod fauna of the islands in Antarctica are scarce. During the sixth Turkish Antarctica Expedition (TAE 6) to the islands (Dismal, Horseshoe, Nansen, Livingstone) in Western Antarctica, sediment and water samples were collected from 32 different water bodies (lakes, ponds, creeks, springs, littoral zones of sea). Among several new reports of different taxonomic groups which are under investigation, a new marine ostracod species (Xestoleberis nansenensis n. sp.) was encountered from Nansen Island. This is the first report of an ostracod from this island below 60° S in Antarctica. The new species has several different features both in the carapace and soft body parts. Absence of ostracods from other islands sampled may be related to several a/biotic factors, such as water chemistry (e.g., relatively low calcium levels), extreme aquatic conditions (e.g., low-temperature values), improper habitat conditions (e.g., too little or absence of sediment in the water bodies), and isolation of the island(s) from the mainland. Although our new species is a marine form, comparative literature review indicated that there is no non-marine living ostracod species reported from the islands visited during the expedition. Possible reasons are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Arid Land Geography is the property of Chinese Academy of Sciences, Xinjiang Institute of Ecology & Geography and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Groundwater resource management is crucial for promoting sustainable development in areas with surface water scarcity, such as Hua County in China. This paper aims to estimate groundwater recharge and evaporation during the pre- and post-rainy seasons in Hua County. The non-equilibrium evaporation model was established to quantify the degree of evaporation. Ternary end-member mixing analysis (EMMA) was used to evaluate the contributions of recharge sources to groundwater recharge. The concentrations of major ions in surface water and groundwater showed some differences, which may be due to differences in their lithological classes and hydrogeochemical evolution. The ion concentrations of both surface water and groundwater were observed to be lower in the post-rainy season, because rainfall infiltration during the rainy season diluted ion concentrations. The Gibbs diagram, end-member diagram, and δ2H versus δ18O diagram all revealed that groundwater was affected by evaporation to some extent, especially in the pre-rainy season. The non-equilibrium evaporation model showed that the remaining proportions of evaporation calculated using 18O and 2H were 0.96 and 0.94%, respectively, during the pre-rainy season and 0.97% and 0.96%, respectively, during the post-rainy season. According to EMMA, the mean contributions of subsurface lateral flow, precipitation infiltration, and river percolation to groundwater were 47%, 28%, and 25%, respectively, during the pre-rainy season and 57%, 30%, and 13%, respectively, in the post-rainy season. The findings of the present study demonstrated that integration of hydrochemistry and isotopic signatures supports better understanding of groundwater recharge and evaporation processes. [ABSTRACT FROM AUTHOR]

The improvement of water management requires monitoring techniques that accurately evaluate water quality status and detect the effects of land use changes on water chemistry. This study aimed to evaluate how multivariate statistical methods and water quality indices can be applied together to evaluate the processes controlling water chemical composition and the overall water quality status of a tropical watershed. Thirty-four water samples were collected in the Formoso River basin, located on the border of the Amazon Forest. Water parameters were measured in situ using a multiparameter and in the lab using spectroscopic and volumetric techniques. The water quality dataset was interpreted through principal component analysis, multivariate linear regression, and water quality indices. Statistical methods allowed us to identify the sources and geochemical processes controlling water quality chemistry, which were carbonate dissolution, runoff/erosion, nutrient input due to anthropogenic activities, and redox reactions in flooded zones. They were also used to create linear functions to evaluate the effects of land use changes on the geochemical processes controlling water chemistry. Conversely, the water quality indices provide information about the overall condition of the water. The Weight-Arithmetic Quality Index correctly evaluates water suitability for its multiple uses, according to the Brazilian guidelines. Conversely, the Ontario Water Quality Index is not suitable to evaluate the water quality of tropical rivers, since the usual higher water temperature and the low oxygen contents associated with tropical environments result in biased water quality evaluations by this index. [ABSTRACT FROM AUTHOR]

Northern regions are undergoing rapid change with wildfires increasing in frequency and severity alongside thawing permafrost and altered water balance. These disturbances could cause significant change in the export of carbon, nutrients, and metals to aquatic systems, with implications for food webs and ecosystem processes. Here, we examine chemical data from a series of 52 streams and rivers that were sampled across a 250,000 km2 expanse of the Taiga Plains and Taiga Shield ecozones of the Northwest Territories, Canada. Samples were collected immediately after and for 3 years following a "megafire" that occurred in this region in 2014, and included wildfire‐affected and non‐affected catchments. While wildfire has been observed to cause significant impacts on water quality in other regions, we here report weak relationships with percent watershed burn with minor to moderate effect sizes, the greatest being a reduction in dissolved organic carbon (−32% concentration). Watershed‐specific properties were a strong driver of large spatial variability in stream water chemistry, which may overwhelm or obscure lesser wildfire effects. The watershed chemical yield‐specific response to wildfire was weaker than the response for concentrations, due to substantial variation and uncertainty in runoff among sites and years. This suggests that watershed chemical yields in this region are more sensitive to changes in water balance due to climate than to altered wildfire regimes. Plain Language Summary: Our study examines how wildfires affect the chemistry of water in northern regions. We collected data from 52 streams and rivers in the Taiga Plains and Taiga Shield ecozones of Canada. The results show that the effects of wildfires on water quality are relatively small. Other factors, such as climate and the presence of wetlands, have a much stronger influence on water chemistry in each ecozone. Understanding these changes in water chemistry is crucial for managing aquatic ecosystems. However, we found that the impact of wildfires on water quality in this region differs from that in other locations. The variability in runoff among different sites and years also adds uncertainty to our findings. Looking ahead, climate change and altered hydrology may have more substantial impacts on fluvial networks compared to wildfires in this rapidly changing region. Our research provides valuable insights into the relative importance of various landscape factors in regulating water quality, including the effects of wildfires. By examining the chemical changes occurring due to wildfires and considering the broader environmental context, we contribute to a better understanding of how these factors influence water quality in northern regions. Key Points: Wildfires in the Taiga regions of Canada had modest effects on water chemistry, with the largest impact being a reduction in DOC (−32%)Variability in stream water chemistry was driven by watershed‐specific properties overshadowing the influence of wildfiresFuture impacts on streams are likely more substantially driven by climate and altered hydrology than increasing wildfire frequency [ABSTRACT FROM AUTHOR]

Fires can burn canopy fuel and replace leafy crowns with charred branches and trunks, thereby affecting hydrological flow and water chemistry. However, little is known about the effects of fire on throughfall volumes and chemical fluxes in temperate forests. Therefore, we aimed to monitor the volume and chemistry of throughfall in pine trees (Pinus densiflora) damaged by the 2022 Gangneung-Donghae Forest fire in the Republic of Korea. Immediately after the forest fire, funnel-type measurements were performed to collect the throughfall beneath five trees at foliage necrosis and crown consumption sites. The amount of water that penetrated in a specified period was continually measured and analyzed in terms of the water quality components. Crown consumption resulted in the passage of more water due to the removal of the tree canopy; however, the ratio of throughfall to total rainfall remained constant as the rainfall amount increased. The throughfall volume was not significantly different owing to the fire damage. The solute concentrations of Ca and TOC at the crown consumption site were higher than those at the foliage necrosis site after the fire; however, no significant difference was observed three months after the fire. In this study, the changes in the amount and water quality of throughfall due to fire were examined over a relatively short period, providing fundamental data for nutrient cycling management of wildfire-damaged soil. [ABSTRACT FROM AUTHOR]

Context. In total, 43 shallow waterbodies were sampled in 1983 in the vicinity of Casey Station and nearby islands in Antarctica. The following physico-chemical parameters were obtained: water and air temperature, pH, conductivity, dissolved oxygen, plus major and minor elements. Aims. To identify the physico-chemical characteristics of these waters and determine their origin, and calculate theirmineral saturation indices. Methods. Waterswere analysed using standardmethods, including for some elements, flame-atomic absorption spectrometry, spectrophotometry, ion chromatography and gravimetric determination. Mineral saturation indices were calculated using the PHREEQ program. Key results. Water salinities were generally low and in the range of 120-1200mg L-1 (total dissolved solids, TDS), except for one site connected to the sea, and four slightly saline sites. The Na/Cl, Cl/Br and Ca/SO4 ratios of several waters were in the vicinity of seawater ratios, implying a contribution of marine aerosols. However, the Mg/Ca ratio of most waters departed from the seawater ratio, plus there was concordance between the molar ratios of (Na + K)/(Ca + Mg) of many of the waters sampled and those calculated from rock geochemical analyses from diverse lithologies. Such chemical 'provincialism' appears to be dictated by rock composition. Nitrate and phosphate concentrations were high in the vicinity of penguin rookeries. Conclusions. Two sources of ions are identified, one as marine aerosols as shown by three sets of ratios (Na/Cl, Cl/Br and Ca/SO4) with known marine values, and the other from the weathering of local rocks as shown by (Na + K)/(Ca + Mg) of the lake waters compared to the same ratios for the surrounding rocks. Only a few waterbodies have saturation levels for several carbonate minerals (calcite, aragonite, dolomite and rhodochrosite). Implications. Future work is recommended for monitoring the waterbodies surrounding Casey Station as a result of the increased atmospheric CO2 concentration that has occurred over the past 40 years, and likely also with the cessation of building activities around Casey Station. [ABSTRACT FROM AUTHOR]

Copyright of Carsologica Sinica is the property of Institute of Karst Geology, CAGS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Carsologica Sinica is the property of Institute of Karst Geology, CAGS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Carsologica Sinica is the property of Institute of Karst Geology, CAGS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Carsologica Sinica is the property of Institute of Karst Geology, CAGS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)