Arsenic shapes the microbial community structures in tungsten mine waste rocks.

Tungsten (W) is a critical material that is widely used in military applications, electronics, lighting technology, power engineering and the automotive and aerospace industries. In recent decades, overexploitation of W has generated large amounts of mine waste rocks, which generate elevated content of toxic elements and cause serious adverse effects on ecosystems and public health. Microorganisms are considered important players in toxic element migrations from waste rocks. However, the understanding of how the microbial community structure varies in W mine waste rocks and its key driving factors is still unknown. In this study, high-throughput sequencing methods were used to determine the microbial community profiles along a W content gradient in W mine waste rocks. We found that the microbial community structures showed clear differences across the different W levels in waste rocks. Notably, arsenic (As), instead of W and nutrients, was identified as the most important predictor influencing microbial diversity. Furthermore, our results also showed that As is the most important environmental factor that regulates the distribution patterns of ecological clusters and keystone ASVs. Importantly, we found that the dominant genera have been regulated by As and were widely involved in As biogeochemical cycling in waste rocks. Taken together, our results have provided useful information about the response of microbial communities to W mine waste rocks.

Coupled controls of the infiltration of rivers, urban activities and carbonate on trace elements in a karst groundwater system from Guiyang, Southwest China.

Hydrogeochemical processes of trace elements (TEs) are of considerable significance to river water and groundwater resource assessment and utilization in the karst region. Therefore, seven TEs were analyzed to investigate their contents, spatial variations, sources, and controlling factors in Guiyang, a typical karst urban area in southwest China. The results showed that the average content of TEs in river water (e.g., As = 1.44 ± 0.47 µg/L andCo = 0.15 ± 0.06 µg/L) was higher than that of groundwater (e.g., As = 0.51 ± 0.42 µg/L andCo = 0.09 ± 0.05 µg/L). The types of groundwater samples were dominated by Ca/Mg-HCO3 and Ca/Mg-Cl types, while those of the river water samples were Ca-Cl and Ca/Mg-Cl types. Principal component analysis (PCA) and correlation analysis (CA) analyses indicated that As and Mn in the groundwater of the study area were related to river infiltration. The end-member analysis further revealed that river infiltration (As = 0.86-1.81 µg/L, Cl/SO42- = 0.62-0.89) and urban activities (As = 0.21-0.32 µg/L, Cl/SO42- = 0.51-0.89) were two main controlling factors of TEs (e.g., As, Co, and Mn) in the study area. In addition, the ion ratios in river and groundwater samples indicated that the weathering of carbonates was also an important control on the hydrogeochemistry of TEs (e.g., Fe and Mn) in Guiyang waters. This study showed that the trace element (TE) contents of groundwater in the Guiyang area were greatly associated with urban input and river recharge, and provided a new perspective for understanding the geochemical behavior of TEs in urban surface and groundwater bodies, which will help the protection of groundwater in the karst areas of southwest China.

Prediction models and major controlling factors of antibiotics bioavailability in hyporheic zone.

Recently, antibiotics have been frequently detected in the hyporheic zone (HZ) as a novel contaminant. Bioavailability assessment has gradually attracted more attention in order to provide a more realistic assessment of human health risks. In this study, two typical antibiotics, oxytetracycline (OTC) and sulfamethoxazole (SMZ), were used as target pollutants in the HZ of the Zaohe-Weihe River, and the polar organics integrated sampler was used to analyze the variation of antibiotics bioavailability. According to the characteristics of the HZ, the total concentration of pollutants, pH, and dissolved oxygen (DO) were selected as major predictive factors to analyze their correlation with the antibiotics bioavailability. Then the predictive antibiotic bioavailability models were constructed by stepwise multiple linear regression method. The results showed that there was a highly significant negative correlation between OTC bioavailability and DO (P < 0.001), while SMZ bioavailability showed a highly significant negative correlation with total concentration of pollutants (P < 0.001) and a significant negative correlation with DO (P < 0.01). The results of correlation analysis were further verified by Principal Component Analysis. Based on the experimental data, we constructed eight prediction models for the bioavailability of two antibiotics and verified them. The data points of the six prediction models were distributed in the 95% prediction band, indicating that the models were more reliable and accurate. The prediction models in this study provide reference for the accurate ecological risk assessment of the bioavailability of pollutants in the HZ, and also provide a new idea for predicting the bioavailability of pollutants in practical applications.

Phytoavailability and transfer of mercury in soil-pepper system: Influencing factors, fate, and predictive approach for effective management of metal-impacted spiked soils.

Mercury (Hg) contamination and accumulation in food crops is a global threat posing potential health risk to humans. However, Hg phytoavailability in soil-pepper system and its influencing factors largely remain unknown. In this study, a greenhouse pot experiment was conducted to grow peppers using 21 Chinese agricultural soils with varied soil properties and aged Hg levels. Mercury concentration in pepper leaves and fruits ranged from 0.021 to 0.057 mg kg-1 and 0.005-0.022 mg kg-1 respectively, while fruit Hg content in three soils (Anhui, Hubei, Beijing) exceeded the safety limit. Fruit Hg concentration was better positively correlated with soil Mg(NO3)2-extractable Hg content (r = 0.7, P < 0.0001) than soil total Hg content (r = 0.45, P < 0.0001). Highest bioconcentration factor (BCF, ratio of Hg plant to Hg soil) yielded in acidic soils, while the lowest BCF occurred in alkaline soils. Path analysis indicated available-Hg (R2 = 0.40) and total-Hg (R2 = 0.40) had direct positive effects on the pepper fruit Hg concentration, while direct negative effects including pH (R2 = -0.86), organic matter (R2 = -0.7), crystalline-Fe (R2 = -0.68). Those agreed with the stepwise multiple linear regression analysis which yielded a regression predictive model (R2 = 0.73, P < 0.0001). Soil available-Hg, total-Hg, pH, organic matter and crystalline-Fe & Mn were the most influencing factors of Hg phytoavailability. These results provide new insights into the phytoavailability of Hg in soil-pepper system, thus facilitating the management of pepper cultivation in Hg-enriched soils.

A characterization of groundwater fluoride, influencing factors and risk to human health in the southwest plain of Shandong Province, North China.

This study investigated 324 groundwater samples collected from the southwest plain of Shandong Province during the dry and wet seasons. Groundwater fluoride in the study area and the influencing factors were characterized and discussed using statistical analysis, ion ratios, Piper diagrams, the saturation index (SI) and ArcGIS software. In addition, the risk posed by groundwater fluoride to human health was assessed. The results showed that groundwater in the study area had elevated fluoride concentrations, with average dry and wet season concentrations of 1.15 mg·L-1 and 1.08 mg·L-1, respectively. Groundwater fluoride showed consistent spatial variations during the dry and wet seasons, with a significant regionalization pattern of low concentrations in the east and high concentrations in the west. Groundwater F- was significantly negatively correlated with Ca2+ and positively correlated with pH, HCO3- and Na+. Important factors identified as having an effect on groundwater F- in the study area included the balance of dissolution of fluorite and calcite, the weakly alkaline environment and cation exchange. In addition, hydrochemical types of high-fluoride groundwater in the study area were identified as mainly HCO3-Na and SO4·Cl-Na. The assessment of the risk of high groundwater fluoride to human health showed that children are more at risk compared to adults, with the risk during the dry season exceeding that over the wet season. It is recommended that water quality management in the study area prioritize the formulation of measures to mitigate high concentrations of fluoride in groundwater .

Advances in As contamination and adsorption in soil for effective management.

Arsenic (As) is a heavy metal that causes widespread contamination and toxicity in the soil environment. This article reviewed the levels of As contamination in soils worldwide, and evaluated how soil properties (pH, clay mineral, organic matter, texture) and environmental conditions (ionic strength, anions, bacteria) affected the adsorption of As species on soils. The application of the adsorption isotherm models for estimating the adsorption capacities of As(III) and As(V) on soils was assessed. The results indicated that As concentrations in contaminated soil varying significantly from 1 mg/kg to 116,000 mg/kg, with the highest concentrations being reported in Mexico with mining being the dominating source. Regarding the controlling factors of As adsorption, soil pH, clay mineral and texture had demonstrated the most significant impacts. Both Langmuir and Freundlich isotherm models can be well fitted with As(III) and As(V) adsorption on soils. The Langmuir adsorption capacity varied in the range of 22-42400 mg/kg for As(V), which is greater than 45-8901 mg/kg for As(III). The research findings have enhanced our knowledge of As contamination in soil and its underlying controls, which are critical for the effective management and remediation of As-contaminated soil.

Release of toxic elements in fishpond sediments under dynamic redox conditions: Assessing the potential environmental risk for a safe management of fisheries systems and degraded waterlogged sediments.

Waterlogged soils and sediments contaminated with potentially toxic elements (PTEs) constitute a complicated case of degraded areas; their management requires understanding of the dynamic redox-driven PTE mobilization. Such studies about PTE redox-induced dynamics in fishpond sediments are still scarce, but of great importance concerning environmental and human health risk. We studied the redox potential (EH)-induced impacts on the solubility of As, Co, Cu, Mo, Ni, Se, V, and Zn in the sediments of a fish farm in the Nile Delta, Egypt, using an automated apparatus of biogeochemical microcosm. We assessed the fate of elements as affected by the EH-induced changes in pH, Fe, Mn, SO42-, Cl-, and the dissolved aliphatic (DOC) and aromatic (DAC) organic carbon. Sediment redox ranged from -480 mV to +264 mV. Flooding the sediments caused a significant decrease in pH from 8.2 to 5.7. Dissolved concentrations of As, Co, Ni, Se, and Zn, as well as DOC, Fe, and Mn increased under the reducing acidic conditions. The release of As, Co, Ni, Se, and Zn could be attributed to the decrease of EH and the subsequent decrease of pH, as well as to the increase of DOC, and/or the dissolution of Fe-Mn oxides caused by redox reactions. Dissolved concentrations of Cu, Mo, and V increased under oxic conditions and were significantly positive correlated with EH, pH, DAC, and SO42-. This enhancement might be caused by the EH-dependent increase of pH under oxic conditions (particularly for Mo and V), which also led to DAC increase. Sulfide oxidation and the release of the associated elements may have also had a contribution, particularly in the release of Cu. Therefore, the release dynamics of dissolved Cu, Mo, and V in the sediments were controlled, to a certain extent, by the changes of EH/pH, DAC, and sulfur chemistry. We conclude that the biogeochemical differences in the behaviour of the studied elements under variable redox regimes substantially affected the fishponds via possible enhancement of PTE mobilization. Our work shows that the potential environmental risks related to PTE mobilization and fish food security should be taken into consideration for the management of degraded aquaculture systems and waterlogged soils and sediments.

The spatial differentiation of quality of rural life based on natural controlling factors: A case study of Gansu Province, China.

The laws of regional differentiation of county development and influencing factors on the quality of rural life (QRL), affect not only the vital interests of rural residents but also the scientific implementation of rural revitalization strategy. In this paper, taking 87 counties (cities, districts) of Gansu Province as the region of study, we constructed five-dimensional model of QRL index. Then, Pearson correlation, spatial coupling, geographical detector and tradeoff analysis methods were used to analyze the QRL's spatial differentiation and quantitively identify its natural controlling factors. Further, we discussed the mechanism of spatial differentiation of QRL in Gansu Province and provided recommendations for improving QRL. The results show that: (1) QRL in Gansu Province is characterized by spatial heterogeneity and agglomeration, and decreases from west to east. There are five hot spots and four cold spots of QRL. (2) Altitude, slope, precipitation, and distance to the provincial capital (DTTPC) are the natural controlling factors of spatial differentiation of QRL in Gansu Province. Their influences are quantified to be 0.19, 0.37, 0.37 and 0.20, respectively. (3) The tradeoff between QRL and precipitation is the strongest, with root mean square deviation (RMSD) of 0.293. The tradeoff between QRL and altitude/slope/DTTCC are of medium level and decrease successively, with values of 0.238, 0.255 and 0.2 respectively. (4) According to the different influences of natural controlling factors on QRL, Gansu Province was classified into three regional types: natural environment restricted type, resource abundance restricted type and economic location restricted type. Thus, we can improve the QRL on the basis of identifying driving mechanisms in different regions, make policies according to local conditions, and further promote the rural development.

Distribution of dissolved gaseous mercury (DGM) and its controlling factors in the Yellow Sea and Bohai Sea.

Elemental mercury (Hg0) is the major form of mercury (Hg) emitted into the environment via anthropogenic activities, resulting in the distribution of Hg worldwide via atmospheric transport. Hg0 in oceans plays an important role in global Hg cycling, mainly by affecting the oceanic-atmospheric exchange of Hg. Due to the large amounts of Hg that are released into Chinese coastal seas from rivers and other sources, Chinese coastal seas are thought to be important sources of Hg in open oceans and in the atmosphere. There have been some studies on the distribution of dissolved gaseous mercury (DGM) in Chinses coastal seas and their controlling factors. However, most of these studies were focused on the surface seawater. There is still a lack of comprehensive study on the DGM through the entire water column in Chinese coastal seas. In this study, two cruises were conducted in August 2017 and in December 2017 to January 2018 to identify the distribution of DGM and its controlling factors in the Yellow Sea (YS) and the Bohai Sea (BS). The concentrations of DGM were higher in summer (167.5 ±â€¯121.4 pg/L) than in winter (41.5 ±â€¯25.5 pg/L), reflecting a significant seasonal variation in DGM. DGM concentrations in the BS and the YS were higher than in open oceans and lower than in some coastal regions. DGM concentrations were generally highest in the BS, followed by the northern YS and the southern YS in summer, whereas the reverse trend was observed in winter. DGM in seawater presented a complicated spatial distribution pattern, with high DGM concentration areas present both nearshore and offshore areas. This result indicates that both terrestrial input and in situ production may play important roles in controlling the DGM distribution. Correlation and multiple regression analyses suggested that temperature (T) and wind speed may be important factors affecting the seasonal variation in DGM in the YS and the BS, and reactive Hg (RHg), dissolved Hg (DHg), dissolved oxygen (DO) and suspended particulate matter (SPM) play important roles in controlling the spatial distribution of DGM.

Denitrification and the controlling factors in Yunnan Plateau Lakes (China): Exploring the role of enhanced internal nitrogen cycling by algal blooms.

Denitrification plays an important role in nitrogen (N) removal in freshwater ecosystems. This internal process regulates the fluctuations of N concentration, especially for lakes with high nutrients concentrations and long residence time. Lakes in Yunnan plateau (southwestern China) provide typical cases, while studies in this region have been rare. Therefore, we studied denitrification of two lakes (Lake Dianchi in hypereutrophic state and Lake Erhai in mesotrophic) in this region. We used acetylene inhibition technique to quantify potential denitrification rate (PDR) of these lakes in April and August, 2015 and 2016. PDR of the sediments ranged 0-1.21 µmol/(N·m2·hr), and that of overlying water ranged 0-0.24 µmol/(N·L·hr). Then, we used Least Angle Regression to determine the controlling factors for denitrification. Nutrients controlled PDR from two aspects: providing essential nitrogen sources; and affecting the richness and metabolism of denitrifying bacteria. In April, both aspects limited PDR; while only nitrogen sources limited PDR in August, due to depleted nitrate and enhanced denitrifying bacteria activity. Ammonia was most significant to denitrification, indicating that nitrate from nitrification transported to the bottom of well-mixed lake provide major N source by denitrification. The high PDR and low nitrate concentrate in August were evidence of an enhanced internal N cycling by algal blooms.

Major controlling factors and prediction models for arsenic uptake from soil to wheat plants.

The application of current Chinese agriculture soil quality standards fails to evaluate the land utilization functions appropriately due to the diversity of soil properties and plant species. Therefore, the standards should be amended. A greenhouse experiment was conducted to investigate arsenic (As) enrichment in various soils from 18 Chinese provinces in parallel with As transfer to 8 wheat varieties. The goal of the study was to build and calibrate soil-wheat threshold models to forecast the As threshold of wheat soils. In Shaanxi soils, Wanmai and Jimai were the most sensitive and insensitive wheat varieties, respectively; and in Jiangxi soils, Zhengmai and Xumai were the most sensitive and insensitive wheat varieties, respectively. Relationships between soil properties and the bioconcentration factor (BCF) were built based on stepwise multiple linear regressions. Soil pH was the best predictor of BCF, and after normalizing the regression equation (Log BCF=0.2054 pH- 3.2055, R(2)=0.8474, n=14, p<0.001), we obtained a calibrated model. Using the calibrated model, a continuous soil-wheat threshold equation (HC5=10((-0.2054 pH+2.9935))+9.2) was obtained for the species-sensitive distribution curve, which was built on Chinese food safety standards. The threshold equation is a helpful tool that can be applied to estimate As uptake from soil to wheat.

The Physiological Suppressing Factors of Dry Forage Intake and the Cause of Water Intake Following Dry Forage Feeding in Goats - A Review.

The goats raised in the barn are usually fed on fresh grass. As dry forage can be stored for long periods in large amounts, dry forage feeding makes it possible to feed large numbers of goats in barns. This review explains the physiological factors involved in suppressing dry forage intake and the cause of drinking following dry forage feeding. Ruminants consume an enormous amount of dry forage in a short time. Eating rates of dry forage rapidly decreased in the first 40 min of feeding and subsequently declined gradually to low states in the remaining time of the feeding period. Saliva in large-type goats is secreted in large volume during the first hour after the commencement of dry forage feeding. It was elucidated that the marked suppression of dry forage intake during the first hour was caused by a feeding-induced hypovolemia and the loss of NaHCO3 due to excessive salivation during the initial stages of dry forage feeding. On the other hand, it was indicated that the marked decrease in feed intake observed in the second hour of the 2 h feeding period was related to ruminal distension caused by the feed consumed and the copious amount of saliva secreted during dry forage feeding. In addition, results indicate that the marked decreases in dry forage intake after 40 min of feeding are caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding. After 40 min of the 2 h dry forage feeding period, the feed salt content is absorbed into the rumen and plasma osmolality increases. The combined effects of ruminal distension and increased plasma osmolality accounted for 77.6% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality are the main physiological factors in suppression of dry forage intake in large-type goats. There was very little drinking behavior observed during the first hour of the 2 h feeding period most water consumption occurring in the second hour. The cause of this thirst sensation during the second hour of dry forage feeding period was not hypovolemia brought about by excessive salivation, but rather increases in plasma osmolality due to the ruminal absorption of salt from the consumed feed. This suggests the water intake following dry forage feeding is determined by the level of salt content in the feed.

[Controlling Factors of Groundwater Salinization and Pollution in the Oasis Zone of the Cherchen River Basin of Xinjiang].

Groundwater is a vital resource for local human life and production in the oasis zone of the Cherchen River Basin of Xinjiang. Understanding the controlling factors of groundwater salinization and pollution is of great significance for the sustainable utilization of groundwater resources and protection of the ecological environment in desert oasis areas. In light of this, a total of 36 single structure unconfined groundwater samples and 54 multi-layered structure unconfined and confined groundwater samples were collected from the oasis zone of the Cherchen River Basin and evaluated for the distribution characteristics and pollution status of major ions. Hydrogeochemical methods (e.g., Piper diagram, multivariate statistics, Gibbs model, and relationships among ions) were used to determine the main controlling factors of groundwater salinization and pollution. Differences in hydrogeochemical zonation were found from the single structure unconfined aquifers in sloping plains of piedmont areas to the multi-layered structure unconfined and confined aquifers in alluvial-proluvial plain areas, and Cl-Na (87.8%) was the main hydrochemical type in the groundwater of the study area. The quality of single structure unconfined groundwater was starkly better than that of the multi-layered unconfined and confined groundwater, which was mainly caused by Na+ (mean value of 9 969 mg·L-1), Cl- (13 687 mg·L-1), and SO42- (5 840 mg·L-1). Moreover, the natural hydrogeochemical process was the main reason for the deterioration of groundwater quality. The hydrochemistry was mainly controlled by the water-rock interaction and evaporation processes. The mineral dissolution of silicates and evaporites was an important source of chemical ions in the groundwater. Furthermore, the chemical weathering of evaporites combined with the processes of evaporation and cation exchange had a significant influence on the salinization of multi-layered unconfined and confined groundwater in alluvial-proluvial plain areas. In addition, synthetic fertilizers were the main pollution sources of NO3- in groundwater in the intensive agricultural zones.

Proposed simplified methodological approach for designing geopolymer concrete mixtures.

The development of geopolymer concrete offers promising prospects for sustainable construction practices due to its reduced environmental impact compared to conventional Portland cement concrete. However, the complexity involved in geopolymer concrete mix design often poses challenges for engineers and practitioners. In response, this study proposes a simplified approach for designing geopolymer concrete mixtures, drawing upon principles from Portland cement concrete mix design standards and recommended molar ratios of oxides involved in geopolymer synthesis. The proposed methodology aims to streamline the mix design process while optimizing key factors such as chemical composition, alkali activation solution, water content, and curing conditions to achieve desired compressive strength and workability. By leveraging commonalities between Portland cement concrete and geopolymer concrete, this approach seeks to facilitate the adoption of geopolymer concrete in practical construction applications. The proposed mix design guidelines have been validated through examples for concrete cured under different conditions, including outdoor and oven curing. Future research should focus on validating the proposed methodology through experimental studies and exploring cost-effective alternatives for alkali activation solutions to enhance the feasibility and scalability of geopolymer concrete production. Overall, the proposed simplified approach holds promise for advancing the utilization of geopolymer concrete as a sustainable alternative in the construction industry.

Pore structure of the mixed sedimentary reservoir of Permian Fengcheng Formation in the Hashan area, Junggar Basin.

The Permian Fengcheng Formation (P1f.) in the Hashan area, situated on the southwestern margin of the Junggar Basin, has witnessed a remarkable breakthrough in shale oil exploration in recent years with nearly 789 million tons of shale oil resources. As a unique set of mixed sedimentary shales, the Fengcheng Formation in the Hashan area is characterized by mixed sedimentation of terrigenous siliciclastic sediments, authigenic minerals, and tuffaceous materials. However, the understanding of pore characteristics in the mixed sedimentary reservoir still remains limited, prohibiting accurate estimation of the oil content and insights into oil mobility. Scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), X-Ray Computer Tomography (X-CT), and geochemical analysis were performed to investigate the pore size distribution and main controlling factors of the mixed sedimentary reservoir. Results showed that the main pore types in the mixed sedimentary reservoir are intergranular pores and dissolution pores. The pores of the P1f. mixed shales in the Hashan area were classified into II-micropores (< 25 nm), I-micropores (25-100 nm), mesopores (100-1000 nm) and macropores (> 1000 nm). In general, the mixed sedimentary rocks of P1f. formation feature few macropores but a large number of micropores and mesopores. The CS exhibits the most favourable physical properties among all lithofacies. It is concluded that the abundance and maturity of organic matter, mineral composition, sedimentary structure, and diagenesis of reservoir together impact the pore structure in the mixed sedimentary reservoirs. The maturity of organic matter and the content of tuffaceous minerals are the most significant in influencing the pore structure of P1f. shales. Overall, the pore structure of complex lithologic reservoir formed by mixed deposition and its influence on physical properties are studied, and the characteristics of the microscopic pore-throat system of the dominant lithofacies in the Hashan area are clarified, which is of great significance as a guide for the exploration and development of mixed sedimentary reservoirs in continental shale oil in China.

Artificial oil bodies: A review on composition, properties, biotechnological applications, and improvement methods.

In order to simulate the structure of natural oil body, artificial oil bodies (AOBs) are fabricated by the integration of oleosins, triacylglycerols (TAGs) and phospholipids (PLs) in vitro. Recently, AOBs have gained great research interest both in the food and biological fields due to its ability to act as a novel delivery system for bioactive compounds and as a carrier for target proteins. This review aims to summarize the composition and the preparation methods of AOBs, examine the factors influencing their stability. Moreover, this contribution focusses on exploring the application of AOBs to encapsulate functional ingredients that are prone to oxidation as well as improve efficiency involved in protein purification, renaturation and immobilization by reducing the complex steps. In addition, the improvement measures to further enhance the stability and efficacy of AOBs are also discussed. The application of AOBs is expected to be a big step towards replacing existing bioreactors and delivery systems.

[Hydrochemical Characteristics, Controlling Factors and Water Quality Evaluation of Shallow Groundwater in Tan-Lu Fault Zone （Anhui Section）].

To study the hydrochemical characteristics, controlling factors, and groundwater quality of the Tan-Lu fault zone (Anhui section), 86 groundwater samples were taken from the areas surrounding the Tan-Lu fault zone (Anhui section), which included the Jianghuai Wavy Plain, the Yanjiang Hill Plain, and the Dabie Mountains in western Anhui. Descriptive statistics, Piper diagram, Gibbs diagram, ion ratio analysis, saturation index, chloride-alkalinity index, and entropy weight water quality index (EWQI) were used to comprehensively study the hydrochemical characteristics and controlling factors of groundwater and to evaluate its quality. The results showed that the shallow groundwater in the Tan-Lu fault zone (Anhui section) was weakly alkaline, with dominant anions and cations of HCO3-, Ca2+ and Na+, respectively, and the hydrochemical types were mainly HCO3-Ca·Mg and HCO3-Na·Ca. The solute source of groundwater was mainly controlled by water-rock interactions, and the weathering of silicate and carbonate rocks jointly contributed to the formation of the chemical components of groundwater. Strong cation exchange adsorption was an important factor causing Na+ enrichment. The overall quality of groundwater in the study area was good but was polluted to a certain extent by human activities. Most of the groundwater in the Jianghuai Wavy Plain and Yanjiang Hill Plain was not suitable for direct drinking. The results of this research have important implications for the sustainable development and utilization of shallow groundwater resources and environmental protection in the Tan-Lu fault zone (Anhui section).

[Chemical Speciation, Influencing Factors, and Regression Model of Heavy Metals in Farmland of Typical Carbonate Area with High Geological Background, Southwest China].

The speciation of heavy metals in soil is an important factor determining their bioavailability and toxicity, and it is crucial for the scientific assessment of ecological risks posed by heavy metals in soils of typical carbonate areas with high geological background in southwest China. In order to investigate the distribution of speciation of heavy metals in soils of carbonate rock with high geological background, we selected a typical carbonate rock distribution area in Guizhou Province and used the second national soil survey plots as sampling units. A total of 309 topsoil samples were collected from farmland. The improved Tessier seven-step sequential extraction method was used to analyze the seven chemical forms of heavy metals:water-soluble (F1); exchangeable (F2); carbonate-bound (F3); weakly organic-bound (F4); iron-manganese oxide-bound (F5); strongly organic-bound (F6); and residual (F7) forms of arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn). The study found that the residual forms of heavy metals As, Cu, Hg, Ni, Pb, and Zn in the soil accounted for more than 50%, the effective components (F1-F3) accounted for less than 5%, and the potential biological effective components (F4-F6) were less than 45%, indicating low reactivity and low ecological risk. The effective and potentially bioavailable components of Cd accounted for 55.49% and 29.37%, respectively, which were much higher than those of other heavy metals. The ecological risk based on the speciation of heavy metals in the soil was much lower than that based on the total content of heavy metals. The stepwise regression equations could effectively establish the relationship between the bioavailable and potentially bioavailable fractions of Cd, Cu, and Pb and their influencing factors. Total heavy metal contents and pH value were important factors influencing the speciation of heavy metals in soils of carbonate rock with high geological background areas. The enrichment of heavy metal elements in the residual fraction was influenced by long-term zinc smelting activities and the weathering of carbonate rocks into soil. Soil organic matter (OM) and oxide content had a relatively small influence on the speciation of heavy metals in the soil.

Distribution patterns of six metals and their influencing factors in M4 seamount seawater of the Western Pacific.

Metals are crucial to the stability of marine ecosystems, and it is important to analyze their spatial heterogeneity. This study examined the distribution and influencing factors of six metals such as manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) and cadmium (Cd) in M4 seamount of the Western Pacific. The results showed that the factors affecting the distribution of metals are complex. The concentration ranges of Mn, Fe, Co, Ni, Cu, and Cd in the M4 seamount were 0-0.05, 0-0.44, 0-0.0014, 0-0.082, 0.12-0.16, and 0-0.013 µg/L, respectively, roughly equivalent to those of other open seas, however, there were also some differences. Specifically, the distribution of ferromanganese nodules and Co-rich crusts, resulted in a significant increase in the concentration of metals such as Mn, Fe, and Co in the bottom. This study will significantly contribute to our understanding of the spatial heterogeneity of metals in seamount areas.

Identifying the geochemical evolution and controlling factors of the shallow groundwater in a high fluoride area, Feng County, China.

Understanding how groundwater is formed and evolves is critical for water resource exploitation and utilization. In this study, hydrochemistry and stable isotope tracing techniques were adopted to determine the key factors influencing groundwater chemical evolution in Feng County. A total of fourteen wells and five surface water samples were investigated in November 2021. The δD and δ18O compositions show that both surface water and groundwater are recharged from atmospheric precipitation. The dominating order of cations and anions in groundwater appears to be Na+ > Mg2+ > Ca2+ > K+ and HCO3- > SO42- > Cl- > NO3- > F-, respectively. The groundwater hydrochemical facies are mainly characterized by HCO3-Ca-Mg and SO4-Cl-Na types. The chemical evolution of groundwater is dominated by water-rock interaction and cation exchange reactions. The major ions in groundwater are mainly controlled by various geogenic processes including halite, gypsum, calcite, dolomite, Glauber's salt, feldspar, and fluorite dissolution/precipitation. Furthermore, the abundant fluoride-bearing sediments, together with low Ca2+, promote the formation of high F- groundwater. Approximately 85.7% and 28.6% of groundwater samples exceeded the permissible limit for F- and NO3- respectively. Apart from geogenic F-, human interventions (i.e., industrial fluoride-containing wastewater discharge and agricultural phosphate fertilizer uses) also regulate the F- enrichment in the shallow groundwater. Nitrate pollution of the groundwater may be attributed to domestic waste and animal feces. Our findings could provide valuable information for the sustainable exploitation of groundwater in the study area and the development of effective management strategies by the authorities.