Lake Pollution Research Articles

Heavy metals in sediments of the river-lake system in the Dianchi basin, China: Their pollution, sources, and risks

The accumulation of heavy metals in river and lake sediments in basins seriously threatens ecological safety and human health. To manage the basin effectively, it is crucial to understand pollution levels and identify and quantify the sources and risks of heavy metals in rivers and lakes separately for targeted control. In this study, 34 sediment samples were collected from the Dianchi Basin, China, and the pollution, sources, and risks in the river-lake system sediments were systematically analysed for cadmium (Cd), chromium (Cr), arsenic (As), mercury (Hg), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni). The results showed that at least half of the heavy metals in the lakes and rivers exceeded the local soil background values during the flood and dry seasons. Heavy metal concentrations were generally higher in the lakes, with high concentrations in the lakes and nearby rivers. Through positive matrix factorisation and Geodetector traceability discovery, agricultural activities were found to be the main source of heavy metals in river sediments, whereas urban activities were the main source in lake sediments. Ecological risk assessments indicated that Hg and Cd were the main risk factors, causing pollution in lakes due to atmospheric deposition and traffic emissions and moderate pollution in rivers due to atmospheric deposition and agricultural production. Health risk assessments revealed that As and Ni were the main carcinogenic risks, originating from human and industrial activities in lakes, and from agricultural and natural sources in rivers. Children faced higher carcinogenic risks than adults, possibly because of their behaviour and physiology. Overall, the presence of heavy metals, along with their ecological and health risks, was significantly higher in the lakes than in the rivers. This study provides a comprehensive overview of the pollution, sources, and risks of eight heavy metals in the river-lake system of the Dianchi Basin.

Recovering NDVI over lake surfaces: Initial insights from CYGNSS data enhanced by ERA-5 inputs

The escalating water pollution in many lakes has led to more frequent occurrences of algal bloom disasters in recent decades. The severity of these disasters can be assessed through remote sensing techniques, specifically using the Normalized Difference Vegetation Index (NDVI) for measurement. However, NDVI observations using optical sensors are often affected by cloud and fog in areas with numerous water bodies, such as Taihu Lake. Sensors operating in the microwave band can effectively mitigate this issue, particularly the emerging Global Navigation Satellite System Reflectometry (GNSS-R), which offers high temporal resolution and cost-effectiveness. In this paper, we propose a new method to recover lake-surface NDVI on cloudy days, utilizing GNSS-R observables and auxiliary meteorological data in conjunction with a machine learning regression algorithm called Bagging Tree. We also examine the effective range of GNSS-R data within this application scenario. Meanwhile, the Weighted Linear Regression-Laplacian Prior Regulation Method (WLR-LPRM) image gap-filling algorithm is used as a benchmark to evaluate recovery accuracy. The regression coefficient of NDVI retrieved using the proposed method is 0.95, with a root mean square error (RMSE) of 0.021 and a mean absolute error (MAE) of 0.010. Compared to the previous work on GNSS-R algal bloom detection with overall accuracy of 0.82, this work shows significant improvement in both accuracy and utility. The recovery of lake surface NDVI provides detailed insights into algal blooms, including quantifiable metrics such as the amount and spatial distribution, which are crucial for effective monitoring and management. Additionally, the recovered image textures exhibit high clarity and closely resemble the reference NDVI images. Experimental evaluation using simulated and actual cloud blocks indicates the model’s robustness to recover NDVI under varying cloud cover conditions. In summary, this study demonstrates the capability of GNSS-R aided by supplementary data for recovering missing NDVI values on lake surfaces when optical observations are absent for the first time.

Microplastic pollution – a rising threat along an urban lake in the Vellore district of Tamil Nadu, India: abundance and risk exposure

ABSTRACT Lake ecosystems provide vital services, but face escalating threats from synthetic microplastic (MP) pollution driven by human activities, necessitating urgent action. This study investigates MP contamination in Dharapadavedu Lake, Tamil Nadu, India, characterizing its presence and distribution. MPs in water and sediment were assessed using NOAA's standardized protocol. The results indicate that mean concentration of MPs in lakeshore sediment and water was 2.46 ± 1.06 particles/kg and 1.26 ± 0.88 particles/L, respectively. Significantly, medium-sized MPs (500–1,000 μm) were most abundant, comprising predominantly white, red, and green colors with fragments and fiber morphotypes. Attenuated total reflection Fourier transform infrared spectroscopy revealed valuable insights into the polymer composition of MPs in the lake, identifying four primary types: nylon (polyamide), high-density polyethylene, low-density polyethylene, and polypropylene. Pollution load index data reveals that MP pollution levels of 2.26 in sediment and 1.46 in water indicate a moderate to high level of risk. These findings reveal that the repercussions of recreational activities, anthropogenic activities, and fishing practices around the lake contributed to the accumulation of MPs in the lake. This study fills a research gap by investigating MP pollution in Dharapadavedu Lake for the first time, establishing a baseline contamination estimate.

Microplastics and their interaction with microorganisms in Bosten Lake water

Microplastic pollution in inland freshwater lakes, formed from melting ice, atmospheric precipitation, and groundwater, remains under-researched. This study examines microplastic (MPS) presence and distribution in Bosten Lake and their interaction with microorganisms. We employed a Confocal Raman spectrometer to identify MPS types and 16S rRNA high-throughput sequencing to analyze microbial diversity and composition. In May, the lake's average microplastic concentration was 108.20 particles per liter (PCS/L), decreasing to 21.67 PCS/L by October. Transparent and yellow fibrous microplastics, predominantly 0.2–0.5 mm in size, were most common. Key microplastics in May included PEEK (27%), PMMA (25%), and PET (9%), while October saw a prevalence of PET (35%), PS (13%), and PA (9%). Higher microplastic concentrations correlated with reduced microbial diversity. In May, the high microplastic concentration group (MH) showed increased Planctomycetota, while in October, Patescibacteria and Bacteroidota rose significantly in the high plastic group (OH), known for microplastic degradation. MH also had a higher abundance of Cryptomycota compared to OH. Functional analysis indicated that MH had more genes related to bisphenol, benzene, and chlorine compounds, whereas OH had genes linked to methane, nitrogen, and organic matter degradation. Microplastic concentrations peaked near the lake inlet and tourist areas, affecting microbial quantity, diversity, structure, and function. This research enhances our understanding of MPS distribution and environmental microbial shifts in similar settings, providing essential data for environmental management strategies at Bosten Lake.

The nitrate cycling process in a through-flow lake under the water transfer project: Insights from multiple isotopes

The Yangtze River-Huai River Water Transfer Project (YHWTP) is the typical inter-basin water diversion project in China. Large-scale hydraulic engineering projects may lead to potential changes in nitrate cycling, yet this aspect remains poorly studied. Therefore, this study focused on the environmental behavior of nitrates in a typical through-flow lake along the YHWTP, using Wabu Lake as an example. Nitrate was the predominant form of nitrogen pollution in the through-flow lake, and may affected by the input of upstream rivers along YHWTP. In addition, we investigated the nitrate transformation process and sources by multiple isotopes (δ18O-H2O, δD, δ15N-NO3-, δ18O-NO3-) of water and nitrate sources samples. The transformation of nitrate mainly involved nitrification in the through-flow lake. Chemical fertilizer (CF) was the major source (33.0–37.6 %) of nitrate pollution, followed by manure & sewage (M&S) (8.2–37.0 %), soil nitrate (SN) (26.5–31.4 %) and atmospheric precipitation (AP) (3.5–22.8 %) in present study. Uncertainties associated with nitrate sources apportionment were analyzed and followed as: CF > M&S > SN > AP. These results offer insights for managing impacted by nitrate pollution in the other water transfer projects.

Effects of climate warming and declining water quality on the eco-environmental evolution of Jinmucuo Lake: Evidence from sedimentary diatom assemblages

The problem of lake pollution on the Tibetan Plateau has become prominent in recent years because of the warming climate and increased human activity. However, it is difficult to obtain effective indicators to explain the long-term eco-environmental changes in plateau lakes. In this study, a sediment core from Jinmucuo Lake was taken as the research object, and the 210Pb and 137Cs isotopes, diatom assemblages, and climatic and environmental factors were analyzed. The results revealed that the lake had a sedimentation rate of 0.47 cm/a, and the age of the 30-cm sediment core was approximately 1876 AD. Diatom abundances at different ages tend to decrease. During 1876–1999, abundant diatom species, such as Cymbella lanceolata, Navicula sp., Surirella ovalis, Synedra sp., Epithemia adnata, Cymbella pusilla, Amphora ovalis and Tabularia tabulata, which included oligotrophic, mesotrophic, and eutrophic indicator species were detected, and the dominant species were Cymbella lanceolata, Navicula sp., Surirella ovalis and Synedra sp. After 2000, diatoms declined dramatically, and were undetected in most samples. Similarly, the species richness and Shannon‒Wiener index plummeted to 0 in approximately 2002. Canonical correspondence analysis revealed that total nitrogen and organic matter were the main influencing factors of diatom assemblages before 2000, whereas As and mean annual temperature were the main influencing factors after 2000. These findings indicate that diatom habitats have been rapidly destroyed by increasing temperatures and As inputs, even in the presence of abundant nutrients in the lake.

Evaluation of Water Quality and Eutrophication of Typical Lakes in Southeast Hubei, China

Field surveys and sample analyses were conducted from January 2018 to December 2019 on Daye Lake, Cihu Lake, Baoan Lake, and Xiandao Lake to understand the water quality characteristics of typical lakes in southeast Hubei. A fuzzy comprehensive evaluation was conducted and the comprehensive trophic level index was applied to evaluate the lakes’ water quality. The results showed differences in the regional, spatial, and temporal distributions of physical and chemical indicators in typical lakes in southeast Hubei. The fuzzy comprehensive evaluation showed that the water quality levels in Daye, Cihu, Baoan, and Xiandao Lakes for 2018 and 2019 were IV, IV, III, and II and V, IV, III, and II, respectively, with seasonal variations in water quality occurring during the year. The trophic level index results showed that Cihu Lake was mildly eutrophic in 2018 and moderately eutrophic in 2019, and Daye, Baoan, and Xiandao Lakes were mildly eutrophic, mildly eutrophic, and mesotrophic, respectively. Lake water quality was influenced by land use types, landscape configuration, inflowing rivers, precipitation, and interactions between land use and seasons. This study helps us to understand the trend and causes of lake pollution in Southeast Hubei, which is conducive to watershed management and the control of water quality deterioration, and also has an important role in regulating the sustainable development of industry and agriculture in the watershed.

Innovative lake pollution profiling: unveiling pollutant sources through advanced multivariate clustering techniques.

In many developed and developing nations, lakes are the primary source of drinking water. In the current scenario, due to rapid mobilization in anthropogenic activities, lakes are becoming increasingly contaminated. Such practices not only destroy lake ecosystems but also jeopardize human health through water-borne diseases. This study employs advanced hierarchical clustering through multivariate analysis to establish a novel method for concurrently identifying significantly polluted lakes and critical pollutants. A systematic approach has been devised to generate rotating component matrices, dendrograms, monoplots, and biplots by combining R-mode and Q-mode analyses. This enables the identification of contaminant sources and their grouping. A case study analyzing five lakes in Bengaluru, India, has been conducted to demonstrate the effectiveness of the proposed methodology. Additionally, one pristine lake from Jammu & Kashmir, India, has been included to validate the findings from the aforementioned five lakes. The study explored correlations among various physical, chemical, and biological characteristics such as temperature, pH, dissolved oxygen, conductivity, nitrates, biological oxygen demand (BOD), fecal coliform (FC), and total coliform (TC). Critical contaminants forming clusters included conductivity, nitrates, BOD, TC, and FC. Factor analysis identified four primary components that collectively accounted for 85% of the overall variance. Following identification of pollution hotspots, the study recommends source-based pollution control and integrated watershed management, which could significantly reduce lake pollution levels. Continuous monitoring of lake water quality is essential for identifying actual contaminant sources. These findings provide practical recommendations for maximizing restoration efforts, enforcing regulations on pollutant sources, and improving water quality conditions to ensure sustainable development of lakes.

Global patterns of lake microplastic pollution: Insights from regional human development levels

Microplastics have emerged as a pervasive pollutant across various environmental media. Nevertheless, our understanding of their occurrence, sources, and drivers in global lakes still needs to be completed due to limited data. This study compiled data from 117 studies (2016–May 2024) on microplastic contamination in lake surface water and sediment, encompassing surface water samples in 351 lakes and lake sediment samples in 200 lakes across 43 countries. Using meta-analysis and statistical methods, the study reveals significant regional variability in microplastic pollution, with concentrations ranging from 0.09 to 130,000 items/m3 in surface water and from 5.41 to 18,100 items/kg in sediment. Most microplastics were under 1 mm in particle size, accounting for approximately 79 % of lake surface water and 76 % of sediment. Transparent and blue microplastics were the most common, constituting 34 % and 21 % of lake surface water and 28 % and 18 % of sediment, respectively. Fibers were the dominant shape, representing 47 % of lake surface water and 48 % of sediment. The primary identified polymer types were polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Countries like India, Pakistan, and China had higher contamination levels. Positive correlations were found between microplastic abundance in surface water and factors like human footprint index (r = 0.29, p < 0.01), precipitation (r = 0.21, p < 0.05), and net surface solar radiation (r = 0.43, p < 0.001). In contrast, negative correlations were observed with the human development index (r = −0.61, p < 0.01) and wind speed (r = −0.42, p < 0.001). In sediment, microplastics abundance correlated positively with the human footprint index (r = 0.45, p < 0.001). This study underscores the variability in microplastic pollution in global lakes and the role of human activities and environmental factors, offering a valuable reference for future research.

Source identification of organic C and N in suspended particulate matter and sediments in plateau lakes as influenced by trophic status using stable isotopic signatures

Understanding the relationship between suspended particulate matter (SPM), sediment organic C, N stable isotopes, and lake trophic state index (TSI) is essential for managing lake pollution and eutrophication. According to the δ13C, δ15N, and C/N we found that the organic C in SPM and sediment of Caohai Lake primarily originated from macrophytes, while N was sourced from chemical fertilizers, phytoplankton, and aquatic plants. Total nitrogen, total phosphorus, NO3−-N, oxidation reduction potential, and Chl.a were identified as key factors influencing the sources and variations of SPM and sediment organic C and N stable isotopes in Caohai Lake, with a significant linear correlation observed between C, N stable isotopes, and TSI in sediments. To mitigate eutrophication in Caohai Lake, it is recommended that farmers apply fertilizers judiciously to minimize nutrient loss and that aquatic plants be regularly harvested to reduce N release from plant residues.

Morphological responses of ostracods to heavy metal contamination: freshwater ostracods as bioindicators of pollution in Ichkeul Lake and rivers ecosystem, northern Tunisia

Morphological responses of ostracods to heavy metal contamination: freshwater ostracods as bioindicators of pollution in Ichkeul Lake and rivers ecosystem, northern Tunisia

Evaluation of potential adsorbents for simultaneous adsorption of phosphate and ammonium at low concentrations

Evaluation of potential adsorbents to tackle eutrophication caused by low concentrations of phosphate and ammonium are rarely reported in the literature. Besides, the dynamics/mechanisms for removal of these pollutants at low concentration are yet to be explored. In this study we used five different adsorbents, including La-modified zeolite (LMZ), MgFe-modified biochar (MgFe-BC), phoslock, activated alumina (AA), and diatomaceous earth (DE) to evaluate the removal of these pollutants. Among the selected adsorbents in this study, LMZ and AA both exhibited effective and simultaneous adsorption for phosphate and ammonium and the maximum adsorption capacities were 2.47 mg/g and 3.07 mg/g, respectively. The presence of SO42− and CO32− negatively impacted phosphate adsorption, while Fe3+ and K+ ions inhibited ammonium adsorption. LMZ adsorption kinetics was over 3 times faster than other adsorbents within 60 min reaction time. Kinetics studies and isotherms revealed that the removal of phosphate and ammonium was primarily driven by chemical interactions and monolayer adsorption and were better fitted by Langmuir isotherm than the Freundlich isotherm and kinetic study was effectively described by Pseudo-second-order kinetic model. FTIR and XPS analysis revealed that the key mechanisms for phosphate adsorption were electrostatic attraction and inner sphere complexation through ligand exchange, whereas ammonium adsorption was mainly governed by ion exchange. Desorption study revealed that LMZ material was stable after three desorption cycles. This study offers vital knowledge on the nature of adsorption and interactions of potential mesoporous adsorbents with eutrophication-causing pollutants in lakes and rivers and proposes effective remedial mean.

Microplastics pollution in tropical lakes: water, zooplankton, and fish in Central Mexico

The presence of microplastics in freshwater systems can have harmful effects on the food chain. Zooplankton, especially suspension and filter feeders, can ingest microplastics, which can cause adverse effects and transfer them to higher trophic levels. Here, we analyze the presence, abundance, and distribution of microplastics in surface water, zooplankton, and fish in two tropical lakes in central Mexico. We collected water samples in triplicate at three sites in each lake and 120 fish of the genus Chirostoma. From each water sample, 300 rotifers and 150 microcrustaceans were randomly isolated and processed independently. Of the particles found in the water, zooplankton, and fish from both lakes, the fragments were the predominant ones. The total abundance of microplastics in the water column of both lakes varied between 1.2 and 17.0 items L−1. In zooplankton, fragments were found predominantly with up to 0.1 items ind−1, while in fish, up to 4.5 items ind−1 was recorded. Our results confirm the presence of microplastics in different compartments of the food webs of freshwater bodies, water column, zooplankton, and fish. Further work is required on the possible effects of these stressors at the different trophic levels.

Application of Crustaceans as Ecological Markers for the Assessment of Pollution of Brackish Lakes of Bulgaria Based on Their Ability to Accumulate the Heavy Metals Cd, Zn and Ni

The present study aimed to assess the pollution of Bulgarian brackish lakes based on their ability to accumulate the heavy metals Cd, Zn and Ni. Physicochemical parameters, including pH, electrical conductivity and salinity of the waters, were determined by potentiometric methods. The heavy metal content of the water and crustacean samples was determined by atomic absorption spectrophotometry. The highest pH in the investigated lakes (Atanasovsko Lake, Poda and Pomorie Lake) in the period May–September 2021 was found in the month of September, in the waters of Atanasovsko Lake (8.84). The concentrations of Cd measured in Atanasovsko Lake in the fall were in the order of 0.0125 µg/L—the highest value recorded for all the studied water bodies. The concentrations of zinc and nickel in the waters did not exceed the norms in Bulgarian legislation. The dynamics of biogenic elements (Zn and Ni) in crustaceans were inversely proportional to those found in the waters. The levels of the toxicant cadmium as well as the metals zinc and nickel in the species Gammarus spp. and Atremia spp., inhabiting all analyzed water bodies, were significantly lower than those specified in the Bulgarian and European legislation. The pH and electrical conductivity parameters of the tested waters, as well as the concentrations of the heavy metals, cadmium, zinc and nickel, were within the recommended values. High positive correlations were determined between the content of nickel, on the one hand, and cadmium and zinc, on the other, in the organism of the investigated crustaceans. A longer period of research is needed to accurately determine the degree of contamination of these waters.

Evaluation of the efficacy of implementing Ecosystem-Based Management (EBM) strategies within fisheries across the middle and lower Yangtze River basin lakes in China

To mitigate the decline of fishery resources and the exacerbation of water pollution in Chinese lakes and to enhance the potential and sustainable use of lake fisheries, the Chinese government has actively implemented principles and models of ecosystem-based lake fishery management. This includes promoting ecological aquaculture techniques and the “retiring pens to restore lakes” policy. To assess the effects of ecosystem-based management on Chinese lake fisheries, data from 2007 to 2020 were collected for the Qiandao Lake, Tai Lake, Hongze Lake, Luoma Lake, and Gaobao Lake in the middle and lower reaches of the Yangtze River. The study employed Data Envelopment Analysis (DEA) to assess fishing efficiency through a static input-output efficiency model. Additionally, the Malmquist index and distance functions were used for a dynamic comparison of total factor productivity (TFP) across the five lake management models. The results indicate that trends in technological progress, scale efficiency, and TFP were consistent across the lakes from 2013 to 2020. Qiandao Lake, Tai Lake, and Hongze Lake showed a positive average annual growth rate in TFP, with Qiandao Lake having the highest average annual growth rate of 13.2%. In contrast, Gaobao and Luoma Lakes experienced a negative growth rate in TFP. Furthermore, Qiandao Lake exhibited significantly higher technical efficiency than the other four lakes, effectively achieving an efficient state, followed by Hongze Lake. The study demonstrates that technological progress and variations in scale efficiency are the primary factors driving the increase in TFP in fisheries. Promoting ecosystem-based “fishing for water conservation” aquaculture techniques and restricting aquaculture scale through the “retiring pens to restore lakes” policy contribute to enhancing TFP in ecological fisheries.

Assessing the abundance, sources, and potential ecological risk assessment of microplastics using their particle and mass units in Uiam Lake, South Korea

Microplastics (MPs) enter lakes through various pathways, including effluents from wastewater treatment plants (WWTPs), surface runoff, and improperly disposed of plastic waste. In this study, the extent of MPs pollution in Uiam Lake in fall of 2022 and spring of 2023 was assessed by determining both the number (n/m3) and mass concentrations (μg/m3) of MPs. Moreover, the correlation between water quality parameters and MP properties was analyzed, and an ecological risk assessment was conducted. MPs abundance was higher in spring than in fall, probably due to the lifting of coronavirus disease-19 restrictions, melting of ice, higher rainfall, and faster wind speed. Fragment was the dominant shape of the MPs collected, while polyvinyl chloride (PVC) and polyester/polyethylene terephthalate were the frequently detected polymer types of MPs in fall and spring, respectively. There was a moderate positive correlation between the number concentration of MPs and the total nitrogen, total phosphorus (T-P), and total organic carbon levels; in contrast, there was no significant relationship between the mass concentration of MPs and all water quality parameters. However, the abundance (μg/m3) of PVC and polymethyl methacrylate MPs were positively correlated with T-P and electrical conductivity. The pollution load index, polymer hazard index, and potential ecological risk index (PERI) were generally higher when the mass unit of MPs was used due to the presence of large-sized MPs composed of highly hazardous polymers (e.g., polyurethane, PVC, and alkyd). For instance, the PERI value of the WWTP effluent was at the very high level (>1200) in both seasons, regardless of the abundance unit of MPs. Therefore, WWTP effluents may have increased the ecological toxicity of MPs pollution in Uiam Lake.

Temporal variations in dissolved organic matter properties in a eutrophic lake under water dilution and aquatic plant litter decomposition: A simulated microcosm study revealing the environmental and microbial driving factors

Dilution by importing external clean water and restoration of aquatic vegetation are widely applied strategies for improving water quality of eutrophic lakes, while the influence of dilution or aquatic plant litter decomposition on dissolved organic matter (DOM) properties, which is closely associated with the health of aquatic ecosystems, is rarely known. In this study, the temporal variations of DOM properties in the overlying water of a eutrophic lake (Yilong lake in Yunnan, southwest China) under water dilution and aquatic plant litter decomposition were comparatively investigated via a simulated microcosm study using in situ samples. The results showed that water dilution reduced DOM concentration and bioavailability in the overlying water in a short term (about 45 d), and increased DOM humification, but such effect diminished over time. DOM concentration increased substantially during aquatic plant litter decomposition, and reed litter released much more amounts of DOM than that of cattail litter, which dominated by protein-like substances and characterized by high bioavailability and low humification degree. Nutrient (available phosphorus (AP), NH4+-N and TN) contents in the sediment indirectly affected DOM properties by remarkably influencing microbial community compositions and enzyme activities. The strong correlations between the relative abundances of dominant genera Bacillus and Clostridium and concentrations of DOM components implied the important roles of these taxa in DOM transformations. Our findings highlighted the effects and potential mechanisms of dilution and aquatic plant litter decomposition on DOM properties in eutrophic water bodies, and the necessity of proper water diversion and plant litter harvest to reduce endogenous organic pollution in lakes.

Occurrence of microplastics in commercial fish species from the Ethiopian rift valley's Lake Hawassa, Ethiopia.

Microplastics (MPs) have recently been detected as emergent pollutants in the Ethiopian rift valley lakes located close to rapidly expanding towns. We provide the first study of MPs ingestion of commercial fish species from Lake Hawassa, Ethiopia: Catfish (Clarias gariepinus) and Nile Tilapia (Oreochromis niloticus). A total of 60 individual fish species was collected from three sampling sites of lake Hawassa in October 2020. Across all sampling sites, there was a significant difference in ingested MPs between benthic omnivore catfish and pelagic phytoplanktivorous Tilapia (χ2 = 15.864, p < 0.001). The most common size of ingested MPs (84.6%) was 0.5-1mm, with fragments (59.5%) dominating, followed by fibers (25.4%). On average, 4.03 ± 1.33 MPs with sizes ranging between 60μm and 10.53mm were detected per individual. White and yellow MPs were particularly numerous, accounting for 36.8% and 26.4% of the total, respectively. Because Lake Hawassa's fishery is so significant, the potential impact of MP pollution on the lake biota in general, and economically valuable fish species in particular, deserves attention, additional research, and, if possible, early mitigation.

Distribution characteristics, risk assessment, and source analysis of heavy metals in typical lake sediments in Inner Mongolia, China

As an important indicator of water pollution, heavy metals in lake sediments can reflect the severity of pollution in the entire study area. Although the risk assessment of heavy metals in sediment from various lakes has been widely studied, there is a lack of understanding on the overall pollution risk assessment of heavy metals in sediment from Inner Mongolia lakes located in cold and arid regions. This study based on data from 2019 to 2023 on heavy metals (Cu, Zn, Pb, Cr, and Cd) in typical lake sediments in Inner Mongolia, combining toxicity, ground accumulation index, and potential ecological risks with Monte Carlo simulation to evaluate lakes. Furthermore, the origins of heavy metals in lake sediments were quantitatively analyzed using a qualitative analysis and an absolute principal component core–multiple linear regression model. This study presented the following results. Firstly, according to the toxicity index, ground accumulation index, and potential ecological risk coefficient, Cd and Cr were identified as the most hazardous and toxic elements in typical lake sediments in Inner Mongolia. Secondly, the degree of lake pollution in Inner Mongolia followed a heavy to light gradient, with central > eastern > western. The pollution in western lakes primarily originated from natural factors, whereas central lakes were mainly affected by pollutants from industry, agriculture, and human activities. Eastern lakes experienced pollution primarily from animal husbandry activities and natural factors. The comprehensive analysis presented in this study can serve as a valuable reference for the restoration of polluted lakes.

Heavy Metal Risk Assessment from Agriculture in Shallow Tropical Karst Lake, Gunungsewu Karst Area, Java Island, Indonesia

This research investigates the heavy metal pollution in karst lakes, crucial for fisheries, agriculture, and domestic activities. Target metals include Pb, Cd, Cr, Fe, Zn, and Cu. Objectives comprise assessing pollution levels via the Heavy Metal Pollution Index (HPI) and conducting an ecological risk assessment, incorporating the Enrichment Factor, Geoaccumulation Index, and Ecological Risk Index. The Pearson’s correlation and cluster analysis were performed to analyze the connection between samples. Results reveal strong correlations between metals in soil and sediment, such as Pb in soil correlating with Cu in sediment (r = 0.88), Zn in soil with Cu in sediment (r = 0.75), and Zn in soil with Pb in sediment (r = 0.81). Kedokan Lake emerges as the most representative observation (distance 13.1), while Kepleng Lake is the least representative (distance 535). Cluster analysis identifies two distinct clusters: Cluster 1 encompasses Ngrejek Lake, Kedokan Lake, Sodong Lake, Kanigoro Lake, and Ngampelombo Lake. HPI calculations reveal varying contamination levels in lake water and underground river samples within the Bribin Underground River Catchment Area. Notably, one location in Kedokan Lake is categorized as contaminated (HPI value of 188.05). Mean Enrichment Factor values range from no enrichment factor (&lt;1) to low enrichment factor (1–3). Geoaccumulation Index (Igeo) indicates an overall unpolluted classification (Igeo&lt;0) across all sampling sites. These findings underscore the nuanced pollution status in the studied area, emphasizing the importance of continued monitoring and intervention to ensure the sustainability of karst lakes in the face of heavy metal contamination.