Influence Of Anthropogenic Activities Research Articles

Ecological implications and drivers of emerging contaminants in Dongting Lake of Yangtze River Basin, China: A multi-substance risk analysis

Emerging contaminants (ECs) are increasingly recognized as a global threat to biodiversity and ecosystem health. However, the cumulative risks posed by ECs to aquatic organisms and ecosystems, as well as the influence of anthropogenic activities and natural factors on these risks, remain poorly understood. This study assessed the mixed risks of ECs in Dongting Lake, a Ramsar Convention-classified Typically Changing Wetland, to elucidate the major EC classes, key risk drivers, and magnitude of anthropogenic and natural impacts. Results revealed that ECs pose non-negligible acute (30% probability) and chronic (70% probability) mixed risks to aquatic organisms in the freshwater lake ecosystem, with imidacloprid identified as the primary pollutant stressor. Redundancy analysis (RDA) and structural equation modeling (SEM) indicated that cropland and precipitation were major drivers of EC contamination levels and ecological risk. Cropland was positively associated with EC concentrations, while precipitation exhibited a dilution effect. These findings provide critical insights into the ecological risk status and key risk drivers in a typical freshwater lake ecosystem, offering data-driven support for the control and management of ECs in China.

Community Structure Of Seagrass In Southeast Waters Cempedak Island West Kalimantan

Cempedak Island is one of the Coastal and Small Islands Conservation Areas (KKP3K) in West Kalimantan has various marine biological resources and important ecosystems, including seagrass. Seagrass is used as the main food source for dugong, potential habitat for various types of organisms, and potential to be developed as marine ecotourism. On the other hand, seagrass ecosystems faced threats, such as high sedimentation and the influence of anthropogenic activities. It is unknown about the current status of seagrass on Cempedak Island. This research aimed to analyze the structure of seagrass in the southeastern waters of Cempedak Island. Seagrass data collection was carried out in the tidal zone using line transect of 70 m and a quadratic transect of 1x1 m2. Data collection on seagrass and water parameters was carried out in October 2023. Determination of research sites was done using an explorative method based on the presence of seagrass. The seagrass found consisted of 4 species, namely Enhalus acoroides, Cymodocea rotundata, Halodule pinifolia, and Halophila ovalis. Seagrass cover ranged from 9.17–16.74%, with an abundance of 1.4–373.3 ind/m2. The diversity index (H') is in the low to medium category, the uniformity index (E) is in the medium category and the dominance index (C) is in the low category. Conditions of water quality parameters were into the optimal range to support seagrass life.

Using the Heavy Metal and Biotic Indices to Assess Ecological Quality in the Central Area of the East Sea, South Korea

With the rapid development of the South Korean economy, human activities have extensively affected Korea’s coastal environment. A precise ecological quality assessment remains paramount despite the relatively lower impact of human activities on the East Sea compared to the West and South Seas of South Korea. Accurate ecological quality assessments can provide valuable marine environmental protection and management references. In our study, we employed seven indices based on heavy metals and macrobenthos to comprehensively assess ecological quality. Our results indicated the final ecological quality in the central East Sea of South Korea was acceptable at most stations; however, the ecological quality in winter marginally falls short compared to that in spring. The concentration of heavy metals emerges as a significant determinant of the final ecological quality, underscoring the need for subsequent studies to investigate the origins of heavy metals in the central East Sea of South Korea and the influence of anthropogenic activities on heavy metal concentrations. Furthermore, employing a single biotic index proves challenging for accurately assessing ecological quality in the East Sea of South Korea.

The Characterization of Biodiversity and Soil Emission Activity of the “Ladoga” Carbon-Monitoring Site

The global climate crisis forces mankind to develop carbon storage technologies. “Ladoga” carbon monitoring site is part of the Russian climate project “Carbon Supersites”, which aims to develop methods and technologies to control the balance of greenhouse gases in various ecosystems. This article shows the condition of soil and vegetation cover of the carbon polygon “Ladoga” using the example of a typical southern taiga ecosystem in the Leningrad region (Russia). It is revealed that soils here are significantly disturbed as a result of agrogenic impact, and the vegetation cover changes under the influence of anthropogenic activity. It has been found that a considerable amount of carbon is deposited in the soils of the carbon polygon; its significant part is accumulated in peat soils (60.0 ± 19.8 kg × m−2 for 0–100 cm layer). In agrogenically disturbed and pristine soils, carbon stocks are equal to 12.8 ± 2.9 kg × m−2 and 8.3 ± 1.3 kg × m−2 in the 0–100 cm layer, respectively. Stocks of potentially mineralizable organic matter (0–10 cm) in peat soils are 0.48 ± 0.01 kg × m−2; in pristine soils, it is 0.58 ± 0.06 kg × m−2. Peat soils are characterized by a higher intensity of carbon mineralization 9.2 ± 0.1 mg × 100 g−1 × day−1 with greater stability. Carbon in pristine soils is mineralized with a lower rate—2.5 ± 0.2 mg × 100 g−1 × day−1. The study of microbial diversity of soils revealed that the dominant phyla of microorganisms are Actinobacteria, Bacteroidetes, and Proteobacteria; however, methane-producing Archaea—Euryarchaeota—were found in peat soils, indicating their potentially greater emission activity. The results of this work will be useful for decision makers and can be used as a reference for estimating the carbon balance of the Leningrad region and southern taiga boreal ecosystems of the Karelian Isthmus.

Influence of anthropogenic activities on metals, sugars and PAHs in PM10 in the city of Fez, Morocco: Implications on air quality

Particulate matter (PM) is an important component in the atmosphere, affecting air quality, health, radiation balance, and global climate. To assess regional air quality in the city of Fez, an intensive field campaign was carried out in the autumn of 2019 in the Middle Atlas region of Morocco. Aerosol sampling was performed simultaneously at two urban sites in the city of Fez: (1) Fez University (FU), a sub-urban site, and (2) Fez Parc (FP), an urban site located in the city center of Fez, using PM10 collectors. Various laboratory analyses were carried out, including PM mass, trace metals, inorganic ions, OC/EC, sugar compounds, and PAHs. The results indicate that the PM10 mass (61 ng m−3) was comparable at both sites, with a 37–107 ng m−3 range. Most of the 19 investigated PAHs at the FU site (10.2 ± 6.2 ng m−3) were low-molecular-weight PAHs, while the most abundant PAHs at the FP site (6.9 ± 3.8 ng m−3) were mainly higher-molecular-weight PAHs. A diagnostic ratio analysis at both sites indicated that PAHs originated from fossil fuel combustion and traffic emissions from diesel engines, with Ant/(Ant + Phe) and Flu/(Flu + Pyr) ratios averaging 0.22 and 0.84, respectively. PMF analysis identified traffic emissions as a major source (30%), with secondary inorganic aerosols (20%) and biomass burning (14%). Polar plots highlight the dominance of local anthropogenic activities in PM pollution, with vehicular emissions, industrial activities, and biomass burning. This study shows that local sources and combustion processes significantly contribute to PM10 sources in Morocco, providing insights into air pollution mitigation in North Africa.

Elucidation of the dominant factors influencing N2O emission in water-level fluctuation zones in a karst canyon reservoir, southwest China

The water-level fluctuations zones (WLFZs) are crucial transitional interfaces within river-reservoir systems, serving as hotspots for N2O emission. However, the comprehension of response patterns and mechanisms governing N2O emission under hydrological fluctuation remains limited, especially in karstic canyon reservoirs, which introduces significant uncertainty to N2O flux assessments. Soil samples were collected from the WLFZs of the Hongjiadu (HJD) Reservoir along the water flow direction from transition zone (T1 and T2) to lacustrine zone (T3, T4 and T5) at three elevations for each site. These soil columns were used to conduct simulation experiments under various water-filled pore space gradients (WFPSs) to investigate the potential N2O flux pattern and elucidate the underlying mechanism. Our results showed that nutrient distribution and N2O flux pattern differed significantly between two zones, with the highest N2O fluxes in the transition zone sites and lacustrine zone sites were found at 75 % and 95 % WFPS, respectively. Soil nutrient loss in lower elevation areas is influenced by prolonged impoundment durations. The higher N2O fluxes in the lacustrine zone can be attributed to increased nutrient levels resulting from anthropogenic activities. Furthermore, correlation analysis revealed that soil bulk density significantly impacted N2O fluxes across all sites, while NO3−and SOC facilitated N2O emissions in T1-T2 and T4-T5, respectively. It was evident that N2O production primarily contributed to nitrification in the transition zone and was constrained by the mineralization process, whereas denitrification dominated in the lacustrine zone. Notably, the annual N2O efflux from WLFZs accounted for 27 % of that from the water-air interface in HJD Reservoir, indicating a considerably lower contribution than anticipated. Nevertheless, this study highlights the significance of WLFZs as a vital potential source of N2O emission, particularly under the influence of anthropogenic activities and high WFPS gradient.

Potential impacts of coal mining activities on nitrate sources and transport in a karst river basin in southwest China.

Typical sources of nitrate pollution in the fragile ecological environment of karst areas, such as agricultural production activities and domestic sewage, have long attracted serious concern. However, coal development can play an equally significant role in releasing the nitrogen fixed in coal into surface watersheds in the form of nitrate, nitrite, or ammonia, consequently threatening the water quality of surface water systems in mining areas. In this study, a typical karst surface watershed system affected by coal mining activities was selected for an in-depth investigation with the aim of realistically assessing the potential contribution of coal mining to nitrogen pollution. The results reveal increasingly concerning nitrate pollution from August 2020 to November 2021 in the Huatan River watershed under the influence of anthropogenic activities, especially mining development and agricultural production. Given that the nitrogen and oxygen isotope compositions of nitrate do not support the presence of denitrification, the variation in the NO3-/Cl- ratio and the relatively stable Cl- concentration may be a reflection of nitrification. Although the leaching of atmospheric precipitation on the strata in the basin promoted the release of nitrogen associated with coal mining, the higher rate of nitrogen cycling in the oligotrophic mine water environment limited the contribution of coal mining to nitrogen pollution in the surface watershed. Specifically, the contribution of coal mining activities to nitrogen pollution in surface karst river is mainly NH4+-N, which contributes 10% or less to the nitrate input to the waters of the Huatan River. The findings thus highlight the necessity of further uncovering the geochemical cycling process of nitrogen during the transport of mine water in the coal mining environment.

The function and keystone microbiota in typical habitats under the influence of anthropogenic activities in Baiyangdian Lake

Microbe is an essential driver in regulating the biochemical cycles of carbon, nitrogen, and sulfur. In freshwater lake, microbial communities and functions are influenced by multiple factors, especially anthropogenic activities. Baiyangdian Lake consisted of various habitats, and was frequently interfered with human activities. In this study, 16 S rRNA sequencing and metagenomic sequencing were performed to characterize the microbial communities, determine keystone taxa and reveal dominated metabolic functions in typical habitats in Baiyangdian Lake. The results showed that the diversity of microbial community was significantly higher in sediment compared with corresponding water sample. Microbial community showed strong spatial heterogeneity in sediment, and temporal heterogeneity in water. As for different habitats, significantly higher alpha diversity was observed in ecotone, where the interference of human activities was relatively weak. The shared OTUs were distinguished from the keystone taxa, which indicated the uniqueness of microbiota in different ecological habitat. Moreover, the interactions of microbial in ecological restoration area (abandoned fish pond) were relatively simple, suggesting that this ecosystem was relatively fragile compared with others. Based on the metagenomic sequencing, we recognized that the canal, open water, and abandoned fish pond were beneficial for methanogenic and the ecotone might be a hot zone for the oxidation of methane. Notably, most of the microbes that participated in these predominant metabolisms were unclassified, which indicated the hug potential for exploring functional microorganisms in Baiyangdian Lake. This study provided a comprehensive understanding of the ecology characteristics of microbiota in habitats undergoing various human interference in Baiyangdian Lake.

Water Quality and Pollution Status using Principal Component Analysis of Lake Nsezi in Richards Bay, Kwazulu-Natal, South Africa

The water quality of Lake Nsezi in Richards Bay, South Africa was investigated for the possible influence of anthropogenic activities around the lake. Lake water was sampled for a period of one year from May 2014 to May 2015. Physicochemical and bacteriological analysis were compared to regulations of WHO, USEPA and DWAF WQG for aquatic environment and domestic use. Physicochemical parameters measured were within the recommended specifications as per WHO, USEPA and DWAF guidelines for aquatic environment and domestic use at the exception of TDS, Cl and few heavy metals such as Al, Cd, Cu, Fe and Mn. The average content levels for these parameters were: 530±167 mg/L (TDS), 135±92 mg/L (Cl), 0.079±0.11 mg/L (Al), 0.171±0.66 mg/L(Cd), 0.38 ± 0.50 mg/L (Fe), 13.6±15.33 mg/L (Pb). Principal component biplots positively showed some strong and moderate metal loadings of 0.564 (Fe), 0.552 (Pb), 0.928 (Na), 0.893 (Mg), 0645 (Sr) and 0.772 (K) at a variety of sites. Bacteriological parameters content investigated were all above the WHO, USEPA and DWAF guidelines for domestic use for E. coli, heterotrophic plate counts and total coliform counts.

The hydrological regime of Taihu Lake under the influence of anthropogenic activities

Study regionThe Taihu Lake is located at the downstream of the Yangtze River, China, which serves various functions such as regional flood control, drought resistance, and drinking water for many vital cities in China such as Shanghai, Hangzhou and Suzhou. Since 1950 s, Taihu Lake has experienced three stages of anthropogenic management. Due to these managements, the natural hydrologic properties of Taihu Lake are gradually disappearing, and the Taihu Lake tends to become an artificially controlled lake. Study focusTo understand how anthropogenic activities have impacted the hydrological regime of Taihu Lake at different stages, this study has analyzed daily average water level of Taihu Lake for 70 years and daily average precipitation data of the Taihu Lake Basin for 60 years. And finally it reveals the natural and anthropogenic effects on trend, amplitude, period and extreme water level of Taihu Lake. New hydrological insights for the regionThe multi-year average water level of Taihu Lake witnesses an increment of 0.23 m, and the contribution from anthropogenic activities account for 34.78%. The maximum decrements of frequency of extreme high and low water level drops by 29.55% and 7.69% recently due to anthropogenic activities. The anthropogenic activities on the hydrological regime in Taihu Lake has become increasingly pronounced, and these hydrological changes are beneficial for basin flood control and water resources.

Hydrogeochemical Characteristics and Evolution Processes of Karst Groundwater Affected by Multiple Influencing Factors in a Karst Spring Basin, Eastern China

Karst groundwater is an important water supply, especially in northern China. With the rapid development of China’s economy, anthropogenic activities have had a significant impact on karst groundwater formation, circulation and other processes. In this paper, the Baotu spring basin, which is closely related to anthropogenic activities, was selected as the research object to carry out a study of water chemical characteristics and evolutionary processes. And, mathematical statistics, Piper trilinear diagram, Gibbs diagram, and ion ratio methods were used to analyze the characteristics and evolution processes of groundwater. The results of this study show that the hydrogeochemical components of karst groundwater are mainly controlled by the weathering of rocks, mainly by the dissolution of carbonate rocks and silicates with the dominant cation of Ca2+ and the dominant anion of HCO3−. Considering the role of anthropogenic activities, including agricultural and industrial activities, the evolution process of karst groundwater is mainly controlled by hydrogeochemical effects such as mineral dissolution and filtration, the mixing of multiple water bodies, anthropogenic activities (domestic sewage, industrial and agricultural wastes), oxidation–reduction and cation alternating adsorption. Moreover, the influence of anthropogenic activities on the formation and evolution of karst groundwater gradually increases, leading to the rise in nitrate content in karst groundwater and accelerating carbonate rock dissolution. The research results of this paper can provide a favorable reference for environmental protection and research on karst groundwater in areas of intensive anthropogenic activity.

Influence of Anthropogenic Activities on the Water Quality of an Urban River in an Unplanned Zone of the Amazonian Coast

The database on water quality in Amazonian rivers located in unplanned urbanized regions along the Brazilian Amazon Coast is still quite limited. This study addresses these concerns, and the tested hypothesis was that the water quality of the Cereja River has deteriorated in recent years, despite the efforts of government authorities to mitigate anthropogenic impacts. To assess changes in water quality, seven campaigns were conducted, collecting data at six fixed points during two different periods. High-resolution satellite images were used to document unplanned occupation. Unfortunately, the number of houses along the Cereja River has increased, in violation of the law. This has contributed to the river’s intense trophic condition, lower dissolved oxygen concentrations, higher concentrations of pathogenic bacteria, and loss of vegetation cover. According to national water quality standards, the Cereja is unsuitable for any human use. This is in stark contrast to the scenario a few decades ago when the river was used for leisure, fishing, and other activities. The results obtained confirm the initial hypothesis and can support potential management strategies and decision-making by authorities. The observed scenario can be extrapolated to other rivers located in urban areas in the Amazon region that have similarly regrettably experienced relatively uncontrolled growth.

FOREST FIRE RISK MAPPING FOR THE HIMALAYAN STATE UTTARAKHAND USING GOOGLE EARTH ENGINE

Abstract. Climate change has exacerbated the intensity as well as frequency of forest fire events in the Indian state of Uttarakhand. The present study focusses on undertaking forest fire risk mapping across the state by utilizing geospatial technology along with Google Earth Engine. Ten parameters were identified that have a strong influence in determining fire prone areas. The Analytic Hierarchy Process (AHP) was then implemented for the development of the risk map in which criteria weights were assigned to the parameters based on their ability to influence a forest fire event. The analysis revealed that out of the total forest area, 24.22% is under ‘very high’ risk zone, 29.24% is under ‘high’ risk zone, 18.23% is under ‘moderate’ risk zone, 7.69% is under ‘low’ risk zone and 20.62% is under ‘very low’ risk zone of forest fire. Further study was carried out to determine fire risk levels in populated regions and in some of the most critical nature reserves having high ecological importance which reveals that ‘very high’ and ‘high’ risk zones have greater population density indicating the influence of anthropogenic activities on forest fire occurrence. The results additionally indicate that four national parks and wildlife sanctuaries are particularly vulnerable to forest fires at present which is a source of concern and requires intervention from the stakeholders.

Exploring the antibiogram of soil isolates from an indian hospital precinct: link to antibiotic usage

ObjectiveHospitals serve as hotspots of antibiotic resistance. Despite several studies exploring antibiotic resistance in hospitals, none have explored the resistance profile of soil bacteria from a hospital precinct. This study examined and compared the antibiogram of the soil isolates from a hospital and its affiliated university precinct, to determine if antibiotic resistant bacteria were present closer to the hospital.Results120 soil samples were collected from JSS Hospital and JSS University in Mysore, India across three consecutive seasons (monsoon, winter and summer). 366 isolates were randomly selected from culture. Antibiotic susceptibility testing was performed on 128 isolates of Pseudomonas (n = 73), Acinetobacter (n = 30), Klebsiella species (n = 15) and Escherichia coli (n = 10). Pseudomonas species exhibited the highest antibiotic resistance. Ticarcillin-clavulanic acid, an extended-spectrum carboxypenicillin antibiotic used to treat moderate-to-severe infections, ranked highest amongst the antibiotics to whom these isolates were resistant (n = 51 out of 73, 69.9%). Moreover, 56.8% (n = 29) were from the hospital and 43.1% (n = 22) were from the university precinct, indicating antibiotic resistant bacteria were closer to the hospital setting. This study highlights the effect of antibiotic usage in hospitals and the influence of anthropogenic activities in the hospital on the dissemination of antibiotic resistance into hospital precinct soil.

Combining hydrochemistry and 13C analysis to reveal the sources and contributions of dissolved inorganic carbon in the groundwater of coal mining areas, in East China.

East China is a highly aggregated coal-grain composite area where coal mining and agricultural production activities are both flourishing. At present, the geochemical characteristics of dissolved inorganic carbon (DIC) in groundwater in coal mining areas are still unclear. This study combined hydrochemical and carbon isotope methods to explore the sources and factors influencing DIC in the groundwater of different active areas in coal mining areas. Moreover, the 13C isotope method was used to calculate the contribution rates of various sources to DIC in groundwater. The results showed that the hydrochemical types of groundwater were HCO3-Ca·Na and HCO3-Na. The main water‒rock interactions were silicate and carbonate rock weathering. Agricultural areas were mainly affected by the participation of HNO3 produced by chemical fertilizer in the weathering of carbonate rocks. Soil CO2 and carbonate rock weathering were the major sources of DIC in the groundwater. Groundwater in residential areas was primarily affected by CO2 from the degradation of organic matter from anthropogenic inputs. Sulfate produced by gypsum dissolution, coal gangue accumulation leaching and mine drainage participated in carbonate weathering under acidic conditions, which was an important factor controlling the DIC and isotopic composition of groundwater in coal production areas. The contribution rates of groundwater carbonate weathering to groundwater DIC in agricultural areas and coal production areas ranged from 57.46 to 66.18% and from 54.29 to 62.16%, respectively. In residential areas, the contribution rates of soil CO2 to groundwater DIC ranged from 51.48 to 61.84%. The results will help clarify the sources and circulation of DIC in groundwater under the influence of anthropogenic activities and provide a theoretical reference for water resource management.

Spatial variations, health risk assessment, and source apportionment of soil heavy metals in the middle Yellow River Basin of northern China

The ecological and environmental problems in the Yellow River Basin of northern China have attracted widespread research attention. This study focused on the soil heavy metals (HMs) in the middle Yellow River Basin; the spatial variations of soil HMs were analyzed using geostatistical techniques, the pollution status and health risks were comprehensively assessed through multiple methods, and the sources of soil HMs were apportioned using a positive matrix factorization (PMF) model. The results showed that the spatial patterns of soil HMs in the study area with a high coefficient of variation (>20 %) exhibited obvious regional zoning, at a low level in the north and a high level in the south. The soil with significantly high HM content was mainly located in the vicinity of industrial cities and usually featured large enrichment factor values (>1.5), especially with respect to Hg, Cd, and Pb, indicating some influence of anthropogenic activities on soil HMs. Based on the comprehensive assessment method, it was found that soil in the study area was clean and safe on the whole, but relatively severe pollution and relatively high risks were found in the strip area of urban agglomeration, including in Tongchuan and Weinan. Further, Hg, Cd, and Pb – with a cumulative contribution of >85 % – were the primary elements to cause soil pollution, while As and Pb were the primary objects leading to health risks, with a cumulative contribution of >95 %. After quantitative analysis using a PMF model, five sources of soil HMs were identified in the south and their contributions decreased in the following order: natural source (43.25 %), industrial source (21.09 %), mixed source (13.15 %), agricultural source (13.11 %) and traffic source (9.40 %). Moreover, some key areas were delineated both with the combined pollution of soil HMs and the relatively high health risk for children. These key areas should be paid more attention to and the Hg, Cd, Pb, and As should be the main objects of prevention and control in the middle Yellow River Basin.

Major ion compositions, sources and risk assessment of karst stream under the influence of anthropogenic activities, Guizhou Province, Southwest China.

To explore the influence of different types of anthropogenic activity on the rivers, we investigate the major ion composition, sources and risk assessment of the karst stream (Youyu stream and Jinzhong stream), which are heavily influenced by mining activities and urban sewage, respectively. The chemical compositions of the Youyu stream water, which is heavily influenced by mining activities, are dominated by Ca2+ and SO42-. However, the chemical compositions of the Jinzhong stream water, which is heavily influenced by urban sewage, are dominated by Ca2+ and HCO3-. The Ca2+, Mg2+ and HCO3- in Jinzhong stream are mainly derived from rock weathering, while the Youyu stream is affected by acid mine drainage, and sulfuric acid is involved in the weathering process. Ion sources analysis indicates that the Na+, K+, NO3-, and Cl- in the Jinzhong stream mainly derive from urban sewage discharge; but NO3- and Cl- of the Youyu stream mainly derive from agricultural activities, and Na+, K+ are mainly from natural sources. The element ratios analysis indicates the ratio of SO42-/Mg2+ in Youyu stream (4.61) polluted by coal mine is much higher than that in Jinzhong stream (1.29), and the ratio of (Na++K++Cl-)/Mg2+ in Jinzhong stream (1.81) polluted by urban sewage is higher than Youyu stream (0.64). Moreover, the ratios of NO3-/Na+, NO3-/K+, and NO3-/Cl- in the agriculturally polluted Youyu stream were higher than those in the Jinzhong stream. We can identify the impact of human activities on streams by ion ratios (SO42-/Mg2+, (Na++K++Cl-)/Mg2+, NO3-/Na+, NO3-/K+, and NO3-/Cl-). The health risk assessment shows the HQT and HQN for children and adults are higher in Jinzhong stream than in Youyu stream and the total HQ value (HQT) of children was higher than one at J1 in the Jinzhong stream, which shows that children in Jinzhong stream basin are threatened by non-carcinogenic pollutants. Each HQ value of F- and NO3- for children was higher than 0.1 in the tributaries into Aha Lake, indicating that the children may also be potentially endangered.

A hydrochemical and isotopic approach for source identification and health risk assessment of groundwater arsenic pollution in the central Yinchuan basin

Arsenic contamination of groundwater is becoming a major global issue as it can severely affect the safety of drinking water and human health. In this paper, 448 water samples were investigated to study the spatiotemporal distribution, source identification and human health risk of groundwater arsenic pollution in the central Yinchuan basin by applying a hydrochemical and isotopic approach. The results showed that arsenic concentrations in groundwater ranged from 0.7 μg/L to 26 μg/L with a mean of 2.19 μg/L, and 5.9% of samples were above 5 μg/L, indicating the arsenic pollution of groundwater in the study area. High arsenic groundwater was mainly distributed in the northern and eastern areas along the Yellow river. The main hydrochemistry type of high arsenic groundwater was HCO3·SO4–Na·Mg, and the dissolution of arsenic-bearing minerals in sediment, irrigation water infiltration and aquifer recharge from the Yellow river were the main sources of arsenic in groundwater. The arsenic enrichment was dominantly controlled by the TMn redox reaction and the competitive adsorption of HCO3−, and the influence of anthropogenic activities was limited. The health risk assessment suggested that the carcinogenic risk of As for children and adults greatly exceeded the acceptable risk threshold of 1E-6, displaying a high carcer risk, while the non-carcinogenic risks of As, F−, TFe, TMn and NO3− in 2019 were largely higher than the acceptable risk threshold (HQ > 1). The present study provides insight into the occurrence, hydrochemical processes and potential health risk of arsenic pollution in groundwater.

Status of different anthropogenic organic pollutants accumulated in sediments from Olt River Basin, Romania: From distribution and sources to risk assessment

Some organic pollutants including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) have been banned from production worldwide, but due to their toxicity and persistence are still of concern. Also, unintentional by-products of combustion and industrial processes such as polycyclic aromatic hydrocarbons (PAHs), represent a permanent threat to the safety of the environment and the population. In this study, surface sediment samples from the middle and lower Olt River Basin (ORB), Romania, including dams, the main tributaries and the confluence with Danube River were collected during seasonal sampling campaigns in 2019 and analyzed for 13 OCPs, 12 PCBs and 15 PAHs in order to evaluate the impact of the main anthropogenic activities in the area (industrial activities and agriculture) and the ecological status of the ORB. The registered levels of OCPs, PCBs and PAHs in surface sediments varied from low to significantly polluted environments, indicating a clear spatial distribution between sites based on concentrations and congener profiles correlated with the influence of anthropogenic activities in the surrounding area. Based on some molecular diagnostic ratio and multivariate statistical analysis, both non-point sources and point sources deposition by surface runoff or atmospheric deposition were identified. Overall, the contamination profile of the study area reveals significant amounts of organochlorine compounds, resulting from the industrial production of chlorinated products, including lindane, but also from the long-term agricultural use of both HCHs and DDTs, more than half of the sites having levels that pose a potential risk for benthic organisms. Therefore, levels of POPs in the hot-spots sampling locations raise numerous concerns about the safety of the environment and the population in the region, requiring immediate actions.

Environmental predictors of lake fish diversity across gradients in lake age and spatial scale

Abstract Freshwater ecosystems have experienced a great loss of biodiversity in the recent century due to eutrophication and loss of habitats, particularly in agricultural lowlands. Some of these ecosystems have recently been re‐established, or entirely new lakes have been created to improve nutrient removal, biodiversity, and recreation. Fish have an important structuring role in lake ecosystems, but little is known about the temporal development of fish species richness or composition in new or re‐established lakes, especially in comparison with natural lakes. We investigated the influence of environmental variables and landscape features on fish species richness and fish assemblage in drainage basins and in 34 new (between 0 and 99 years) and 193 natural lakes in Denmark, using structural equation modelling. Fish species richness in drainage basins is influenced primarily by basin elevation, lake area, and salinity at the basin outlet; low‐salinity coastal regions are important migration pathways for many freshwater fish species, not just for anadromous or catadromous species. Land use does not appear to influence richness at the drainage basin scale, indicating that the influence of anthropogenic activities is minor or that significant effects thereof occurred a long time ago (decades to centuries). The drainage basin richness defines the apparent pool of species that may colonise lakes within the basin, but the actual number of species is particularly influenced by stream network connectivity. Disconnected lakes have fewer species, a deficit that is sustained over long time scales. In addition to the influence of stream connectivity, lake characteristics such as elevation, surface area, and water chemistry (alkalinity and pH) are also important predictors of fish species richness, whereas we did not find any effect of lake nutrient concentrations. The direct effect of land use was not evaluated. Ordination analysis shows that fish assemblage depends on both lake type (new/natural) and stream connectivity (connected/disconnected). Furthermore, species‐specific occurrences reveal some differences between new and natural lakes and indicate that stocking plays a role in new lakes. While new and natural lakes may initially differ in terms of both how many and which species they contain, they converge over time in a process that can be enhanced by improving stream connectivity.