Lake Pollution Research Articles

Plastic pollution in rivers and lakes—An indicator of an even bigger consequence of global change?

Fish and FisheriesVolume 22, Issue 3 p. 465-466 EDITORIAL Plastic pollution in rivers and lakes—An indicator of an even bigger consequence of global change? Paul J.B. Hart, Corresponding Author Paul J.B. Hart pbh@le.ac.uk Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK Correspondence Paul J. B. Hart, Department of Neuroscience, Psychology and Behaviour, University of Leicester LE1 7RH UK. Email: pbh@le.ac.ukSearch for more papers by this authorRobert Arlinghaus, Robert Arlinghaus Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Humboldt-Universität, Berlin, GermanySearch for more papers by this author Paul J.B. Hart, Corresponding Author Paul J.B. Hart pbh@le.ac.uk Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK Correspondence Paul J. B. Hart, Department of Neuroscience, Psychology and Behaviour, University of Leicester LE1 7RH UK. Email: pbh@le.ac.ukSearch for more papers by this authorRobert Arlinghaus, Robert Arlinghaus Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Humboldt-Universität, Berlin, GermanySearch for more papers by this author First published: 21 April 2021 https://doi.org/10.1111/faf.12557Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume22, Issue3May 2021Pages 465-466 RelatedInformation

Secchi depth inversion and its temporal and spatial variation analysis—A case study of nine plateau lakes in Yunnan Province of China

Secchi depth (SD) can directly reflect the state of lake water quality, and it is the key to control and improve the lake environment at mastering long-term and large-scale. In this research, deep neural networks algorithm was used to derive SD of 9 major plateau lakes in Yunnan Province from January 2001 to December 2018 based on MODIS remote sensing images, and explored the spatial-temporal variation characteristics with SD by geospatial analysis. The results showed that: (1) The inversion model proposed in this paper had a good performance (RMSE = 0.1359, MAE = 0.1134), which can objectively reflect SD status in the lake. (2) The temporal variation characteristics showed that SD of all lakes has a downward trend with a mean comprehensive change rate of −0.25 m/decade. (3) The spatial variation characteristics showed that the region of higher SD has a larger decline rate, and the trend in the region with lower SD was relatively stable. SD near urban and residential areas was relatively low, and declined fast. (4) Human activities would become an important factor to affect SD changes in the plateau lakes of Yunnan Province, and it was also the main factor causing lake pollution in the Yunnan-Guizhou Plateau.

Novel method to immobilize phosphate in lakes using sediment microbial fuel cells

Phosphate pollution in lakes poses an intractable remediation challenge. Accumulated stocks of phosphorus in sediments cause high concentrations in the overlying water despite elimination of external sources. We propose to use sediment microbial fuel cells (SMFCs) for lake remediation by sediment phosphorus immobilization. The hypothesis is that SMFCs can increase sediment redox potential at the top layer, and that such changes will allow the sediment to retain phosphorus as immobile species. This study placed an emphasis on scalability, practicality, and use of low-cost materials. Stainless steel net was selected as electrode material, and modifications were tested: (i) chronoamperometric operation with anode poised at +399 mV (versus standard hydrogen potential); (ii) injection of graphite slurry; and (iii) coating with nickel-carbon matrix. Stainless steel electrodes were implemented in laboratory microcosms (1.3 L) and at field scale in a eutrophic freshwater lake. All tests were carried out in untreated sediment and water from Lake Søllerød, Denmark. Phosphate immobilization was shown at lab scale, with 85% decrease in overlying water using steel electrodes. At field scale maximum phosphate decrease of 94% was achieved in the water body above a 16 m2 stainless steel SMFC electrode. Results are promising and warrant further study, including remediation trials at full scale. Added benefits include degradation of sediment organic matter and pollutants, inhibition of methane and sulfide emission and production of electricity.

Development of an unmanned device with picric acid strip for on-site rapid detections of sodium cyanide in marine water

In this study, a rapid detection method using picric acid test strip for detection of sodium cyanide in ocean water was established, and an automatic-integrated detection device was set up, which can be mounted on an unmanned surface vehicle. The optimal detection conditions were set as follows: for a 100-ml seawater sample, the weight of tartaric acid solid was 1.5 g, 1–2 drops of 150 g/L sodium carbonate were used to soak the picric acid test strip, the heating temperature was 80 °C, and the heating time was 5 min. Under the optimal conditions, the test result was satisfactory and the detection limit of the method achieved was 0.3 mg/L. This method realizes the remote and rapid detection of sodium cyanide in seawater, which greatly improves the detection efficiency and does not require any personnel to enter the contaminated site. It can be widely used for rapid detection scenarios such as leakage accidents from overseas transportation, lake pollution emergencies and on-site screening.

A biomonitoring study: Using the biomarkers in Cyprinus carpio for the evaluation of water pollution in Sapanca lake (Sakarya, Turkey)

This study aims to determine the toxic effects of heavy metal pollution on carp (Cyprinus carpio) in Sapanca Lake by biochemical and histological analyses. For this reason, fish and water samples were taken from the lake in 2015. Heavy metal (Cu, Fe, Zn, Pb, Cd) analyzes in the water column and tissues (muscle, liver, gill) were determined by ICP-OES. CAT, GSH and MDA levels, which are oxidative stress bioindicators in tissues, were measured by spectrophotometric methods. Histopathological findings in tissues were determined by Hematoxylin-Eosin staining. As a result, heavy metal concentrations in water were determined as Fe > Zn > Pb > Cu > Cd. The accumulation of Cu, Fe and Cd in the tissues of the fish were liver > gill > muscle, and the accumulation of Zn was gill > liver > muscle. CAT activity, MDA and GSH level of the tissues changed with the water temperature. General signs of destruction were observed in the gill tissues of the fish. Necrotic conditions in hepatocytes were observed. In conclusion, the presence of biochemical and histopathological findings in tissues suggests that the lake is not only affected by heavy metals but also by other pollutants.

New Classification Method to Evaluate Pollution Levels of Sewage Contaminated Lakes

Monitoring water quality to minimize deterioration of a lake’s functionality is important, as several Indian lakes are exposed to sewage contamination. Public health laboratories, citizen scientists, and volunteers in developing nations often find it difficult to perform elaborate tests to monitor the water quality of freshwater systems. Developing a classification method to evaluate the pollution status of sewage-contaminated lakes using limited tests will expand environmental monitoring of freshwater systems and contribute valuable data to the regional and global repository. Four classes of lake pollution ranging from unpolluted (class 1) to mixed wastewater (class 4) were identified based on the distribution of data points in the K+ (potassium) versus COD (chemical oxygen demand) scatter chart. As pH, EC (electrical conductivity), turbidity, and DO (dissolved oxygen) are deteriorated by sewage contamination, these parameters were also incorporated in the proposed pollution classification table. Data of unpolluted and sewage polluted Indian lakes were employed to compile the limiting range of parameters in the proposed lake pollution classification. The five parameters (K+, pH, EC, DO, turbidity) required to categorize lake pollution (class 1 to 4) can be measured with equipment costing 800–1000 USD, while COD can be measured at 5 USD/sample in laboratories.

Investigation and Analysis of the Main Pollution Sources in Fuxian Lake

Fuxian Lake is a plateau-based freshwater lake. In recent ten years, with the rapid development of the economy around the lake, the water quality of Fuxian Lake has declined and the nutritional status in lake has increased obviously. To identify the main sources of pollution in Fuxian lake and provide a reference for the protection and management direction and theoretical guidance, the pollution status of Fuxian Lake basin was analyzed and evaluated from the aspects of rural domestic pollution, farmland runoff pollution, urban domestic pollution, phosphorous chemical pollution and tourism pollution, respectively, based on years of field investigation and the indexes detection and analysis such as chemical oxygen demand (COD), total nitrogen, total phosphorus. The results showed that the pollution in Fuxian Lake basin mainly came from the rural non-point source pollution, urban domestic pollution, waste phosphate rock area pollution, tourism pollution and other aspects, among which the most important source of pollution was the rural non-point source pollution, including watershed village pollution, human and animal excrement pollution, rural waste pollution, and farmland runoff pollution in the basin. The COD, total nitrogen and total phosphorus from rural non-point source pollution accounted for 94.81%, 94.85% and 87.79% of the total pollution into the lake, respectively. Among them, the farmland runoff pollution was the most important component of rural non-point source pollution

The Environmental Safety of Fish Products

The anthropogenic pollution of the environment leads to the discharge of various pollutants into water ecosystems, which further accumulate in fish and other hydrobionts. Fish is a valuable traditional food source for humans, and the quality assessment for fish products is therefore a relevant problem. This article deals with researching the content of pollutants in game fish, in particular in the Siberian whitefish. The goal of this work is to identify the content of heavy metals and cesium 137 in the muscle tissue and organs of the fish (whitefish) caught in the lower reaches of the Lena River. Research methods: The sampled materials were tested for heavy metals using the atomic absorption method. The content of Cs 137 was established using the spectrometric method. Results: the average concentration values for heavy metals (mg/kg) (Pb, Cd, Hg) in the muscle tissue and organs of the whitefish do not exceed the limits. The average content of lead in muscular tissue is 0.0135±0.0025 mg/kg, cadmium - 0.0076±0.0014 mg/kg, and mercury 0.0011±0.0000 ug. Arsenic was not found in the muscle tissue and organs of the fish. The highest relative content of heavy metals was observed in the livers of the whitefish. The content of cesium 137 is insignificant and below the allowed level of radionuclide activity. Conclusion: The analysis of the research results shows that the contents of heavy metals and cesium 137 in the fish caught in the lower reaches of the Lena do not exceed the standard levels. The on-going pollution of lakes and rivers within the Lena watershed calls for regular monitoring of heavy metal and radionuclide content and accumulation in game fish.

Recording and response of persistent toxic substances (PTSs) in urban lake sediments to anthropogenic activities.

Owing to the intensification of human activities, urban lakes serving as important freshwater resources are becoming seriously deteriorated, especially due to persistent toxic substance (PTS) pollution. Therefore, the spatial distribution and sediment record of PTS in urban lake sediments in the middle Yangtze River Basin were investigated to indicate its response to anthropogenic emission and pollution reduction actions. Spatial distribution of typical PTSs (polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) included) showed that pollutants were concentrated in the southeast and center of the urban lake due to riverine inputs suffering from both petrochemical and municipal wastewaters. The sedimentary record of PAH concentrations indicated an increase from the 1960s to a peak level in the 2000s, which was induced mainly by increased PAH emissions, with PAH levels decreasing subsequently due to craft improvement of wastewater treatment plants (WWTPs). Source apportionment results revealed that historical PAH emissions transferred from petrogenic sources to a mixture of energy combustion and petrochemical industry. Furthermore, OCP and PCB pollutions reached peak levels in 1980s, which is consistent with their historical usage for agricultural and industrial production. From the synthetic sediment quality index (SeQI) analysis, sediment quality in nearly half of sites was poor, while the sediment record suggested that sediment quality had turned better since 2000s maybe due to the WWTP improvement. Furthermore, significant correlations (p<0.05) between PTS levels and the ratio of PAH emissions to the number of WWTPs documented the PTS levels in response to the surrounding anthropogenic pollution and WWTPs in urban lakes.

Evaluation of artificial grooves for collecting bottom sediment pollutants in Lake Chaohu, China.

Internal loadings of nutrients play important roles in the eutrophication of shallow lakes. The effective removal of sediments rich in nutrients is of great importance for lake management and the abatement of eutrophication. In this study, grooves were installed in the bottom of Lake Chaohu. Approximately 8.5 months later, the chlorophyll a, organic matter, and total nitrogen contents in the sediment inside the grooves were 1.5-3.0 times, 1.2-1.8 times, and 1.3-1.6 times higher, respectively, than those in the surrounding sediments, and the total phosphorus contents in the bottom grooves were slightly lower than those in the surrounding sediments. The thicknesses of the sediments with high chlorophyll a, organic matter, total nitrogen, and total phosphorus contents in the grooves were 5-15 times greater than those of the surrounding sediments with high pollution contents. Internal pollution was captured in the grooves. The active hydrodynamic process was an important factor related to the effectiveness of this method and is conducive to the transport of polluted sediments to the bottom grooves where they are collected. Bottom grooves have broad application potential for the removal of sediments rich in nutrients from shallow-water lakes; these grooves can be widely used in areas that experience large disturbances from wind waves, have water flows gathering in or entering the lake, or have thin sediments with high pollution contents. This study provides scientific guidance for the control and management of internal pollution in shallow lakes.

Assessment of metals pollution and subsequent ecological risk in water, sediments and vegetation from a shallow lake: a case study from Ranipet industrial town, Tamil Nadu, India

ABSTRACT The present study investigated the distribution, sources, bioavailable fractions, and ecological risks of nine metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Pb, and Zn) in water, sediment, and vegetation samples collected from a shallow lake within the industrial town of Ranipet, India. The lake water samples exceeded the concentrations of Al, Cd, Cr, Cu, Fe, Mn, and Pb beyond BIS (Bureau of Indian Standards) limits for drinking water with Cr to be highest as 6.73 mg/L. The Geo-accumulation index for lake bed sediment samples were in the order of Cr>Cu>Co>Mn>Zn>Pb. The bioavailability of the metals in sediment samples determined through Sequential Extraction Procedure (SEP) showed Cr>Co>Zn>Cu>Pb>Mn>Fe>Al. The sediment samples collected from the root zone of different plant species (Cynodon dactylon, Sida acuta, and Eclipta prostrata) exhibited varied bioavailable fractions than lake bed sediments, which indicated the influence of plants in mobilising and fixing the metals. The plant samples had metals concentration in the order of Root>Stem>Leaves and showed the possibility of phytoremediation. Principle Component Analysis (PCA) and Pearson Correlation Matrix (PCM) in the lake bed sediment samples identified the clustering of Al and Fe which indicated probable lithological origin. The lone clustering of Cr from Co, Mn, and Cu indicated separate anthropogenic sources. Further Al, Fe, and Mn showed strong correlations with TOC (Total Organic Carbon) substantiate their distribution under influence of TOC. The study indicated elevated metals pollution is water, sediment, and plants samples from lake area which require immediate attention from all the stakeholders. The assessment of pollution in small and shallow lakes amidst industrial belts need to be prioritised as they often become victims of industrial encroachment and cease to exist in long run.

Can the environmental health of urban centers be assessed through pollutants trapped in lakes? A study case in the biggest city of the southern hemisphere.

Air and water quality in urban centers are summited to pollution from different sources, such as industrial activities, traffic, and wastewater effluents. A great number of chemicals can be spread by wind throughout the city, exposing the inhabitants to the health risks associated to them. Atmospheric analysis provides punctual data and represents the timing of the air sampling. A long-term evaluation of the atmospheric air quality can be assessed through the evaluation of pollutants that reach the soil by atmospheric deposition; however, they also can be redistributed and desorbed. The evaluation of pollutants in lakes could be a practical solution, given that lakes may act as traps to these compounds. In this context, organic pollutants were assessed in sediment and water from a lake located in the urban area of São Paulo, Brazil, the biggest city of the southern hemisphere. There were no evidences of sewage input to the lake and pyrogenic compounds reached the lake through atmospheric deposition. The content of pyrogenic PAH exposed the large amount of PAH emitted to the atmosphere by the multiple sources of PAH, mainly vehicular emission and diesel combustion. The PAH trapped in the lake highlighted the impact of all burning process in the air quality in which 12.3 million people are exposed.

Analysis of the Prevention and Control of Inner lake Pollution in China Based on the Game Between the Government and Enterprises

With the rapid development of industrialization, the pollution problem of Inner lakes have become increasingly prominent. Enterprises do not consider environmental costs to pursue profit maximization, and government regulation becomes inevitable. The pollution control process of Inner Lake is actually a game process between enterprises and the government. In the current game analysis, there is a major defect of ignoring the political cost and reputation cost caused by environmental pollution to the government and enterprises, which makes the theory unable to explain the real world. This paper analyzes the static game and mixed strategy game between local government and enterprises, and draws the conclusion that the extra benefit, reputation cost, government supervision cost and political cost of enterprises' pollution of Inner lake all affect the choice of their behaviors. In addition, this paper introduces discount factor, analyzes multi-stage dynamic repeated game, and finds that the enterprise's future choice is closely related to the size of discount factor. Finally, the author puts forward policy Suggestions to promote and improve their behaviors from three aspects. Firstly, the third party constraint mechanism is introduced to increase the political cost of the government and the cost of corporate reputation. Secondly, actively carry out technological innovation to reduce the cost of pollution treatment. Finally, it is necessary to increase the punishment for negligence of government supervision and strengthen the responsibility of government supervision.

Use of the Zebra Mussel Dreissena polymorpha (Mollusca, Bivalvia) as a Bioindicator of Microplastics Pollution in Freshwater Ecosystems: A Case Study from Lake Iseo (North Italy)

The monitoring of microplastics pollution in freshwater environments trails behind its practice in marine ecosystems. We evaluated the use of the invasive zebra mussel (Dreissena polymorpha) as a potential bioindicator of microplastic litter in freshwater lakes. Samples were collected from three sites (Lovere, Costa Volpino, Castro) at the northern end of Lake Iseo (one of the major subalpine lakes in north Italy) and compared for water physicochemical parameters, biometrical features of zebra mussels, and microplastics items/specimens (color, shape, size, and chemical composition). We hypothesized that since a wastewater treatment plant (WWTP) on the Oglio River discharges into this area of the lake, the microplastics in D.polymorpha could be measured and compared in samples from the three sites at different distances from the WWTP. There was no difference in the physicochemical water parameters and biometric features between the samples from the three sites, whereas there was a significant difference in items/specimen between the sites in decreasing order (mean ± standard deviation): Costa Volpino (0.23 ± 0.43) &gt; Lovere (0.07 ± 0.25) &gt; Castro (0.03 ± 0.18). The chi-square test showed a significant difference in shape, color, and chemical composition frequency in the samples from the three sites. The chemical composition of the microplastics was polyethylene terephthalate (45%), nylon (20%), polypropylene (20%), polyamide resin (10%), and polyvinyl chloride (5%). Our data show that the amount of microplastics the zebra mussel accumulated was greater the closer the sampling site to the WWTP. Our findings suggest that the zebra mussel may provide a useful tool to monitor microplastics pollution in lakes.

Analysis of the main factors affecting salinity in Wuliangsuhai Lake

The identification and determination of the main influencing factors of lake salinity play a key role in the control measures and suggestions to prevent lake pollution. To ascertain the salinity status, its evolutionary trend in WL, and its impact on the lake, data describing water quality and the 10 major influencing factors for the period 2003–2012 were employed to analyze the evolutionary process and trend characteristics of the main factors affecting upper irrigation and drainage. The principal component analysis (PCA) method was used to identify the key influencing factors of the salinity of the lake; then, regression analysis was combined with PCA modeling to predict the salinity. Results showed that using a multivariate statistical technique is an effective and objective method for identifying the main influencing factors of salinity in WL, which can provide a scientific basis for the pollution control and environmental management of WL.

For Patients with Celiac Disease: Pay Attention to Polluted Seafood

Chemical pollution of water is the contamination of water by foreign matter that deteriorates the quality of the water. Pollution of water by heavy metals are dangerous because they tend to cause Bioaccumulation that means an increase in the concentration of a chemical in a biological organism over time, compared to the chemical's concentration in the environment. Chemical pollution of Manzala lake was studied in 4 main localities, Kapoty, Bashtier, Mataryia and Gamil areas which receives high load of sewage, agricultural and industrial wastes from different sources. Heavy metals, such as Zn, Pb, Cd and Hg were estimated in water and fish samples, to reveal high pollution of lake Manzala with such toxic elements, where Zn, reached 800µg/L. Pb,195 µg/L. Cd 45 µg/L and. Hg, 5000 µg/L in water samples.

An Effective Machine Learning Scheme to Analyze and Predict the Concentration of Persistent Pollutants in the Great Lakes

Persistent organic pollutants (POPs) are highly toxic and difficult to degrade in the natural ecology, which has a severe negative impact on the ecological environment. Quantifying changes in the concentrations of persistent organic pollutants in the Great Lakes is challenging work. Machine learning (ML) methods are potent predictors that have recently achieved impressive performance on time series tasks. ARIMA model, Linear Regression methods, XGBoost algorithm, and Long Short-Term Memory (LSTM) are commonly used for estimating time-series changes. Traditionally Mean Squared Error (MSE) and Root Mean Squared Error (RMSE) have been standard criteria to measure the error between the actual value and predicted value; however, Euclidean distance (ED) cannot effectively calculate the similarity between two-time series. We proposed an alternative criterion called Penalty Dynamic Time Wrapping (Penalty-DTW) based on Dynamic Time Wrapping (DTW). It can accurately measure the difference between the actual value and the predicted value. We study the benefits of Penalty-DTW vs. ED under the above ML algorithms. Further, considering the machine learning algorithm’s uncertainty, we proposed combining LSTM and deep ensemble methods to quantify algorithms uncertainty and make a confident prediction. We find improved LSTM model outperformed other predictive power models by comparing pollutant concentration prediction. The prediction results show that the concentration of pollutants has a stable downward trend in recent years. Simultaneously, we found that pollutants’ concentration correlates with seasons, which positively guides environmental pollution control in the Great Lakes.

基于深度神经网络算法的水体透明度反演方法

水体透明度能够直观反映湖泊水质状态，掌握长时间大尺度湖泊水体透明度是控制和改善湖泊水生态环境的关键。由于滇池的水质原位监测工作起步较晚，导致长时间序列的历史湖泊水体透明度数据的缺失。为此，以滇池为研究区，以深度神经网络算法为理论基础，以原位监测和MODIS遥感影像为数据，对2001年1月1日-2018年12月31日滇池水体透明度进行反演，并利用地理空间分析方法探讨了滇池湖泊水体透明度时空变化特征。研究结果表明：（1）提出的反演模型具有较好的性能（RMSE=0.1359，MAE=0.1134），能够客观反映湖泊水体透明度状况；（2）时间变化特征分析结果表明，滇池水体透明度总体呈现下降趋势，综合变化率为-0.08 m/10 a；（3）空间变化特征分析结果表明，水体透明度较高的区域下降率较大，水体透明度较低的区域变化趋势相对稳定，距离城区及居民区较近的水体透明度相对较低；人类活动将成为影响滇池水体透明度变化的重要因素，同时也是造成滇池水体污染的主要因素。;Lake is an important ecological resource, which not only determines the quality of regionally ecological environment, but also guarantees the sustainable development of the city. Lake ecological environment can reflect the environmental situation of the region. Secchi depth (SD) can directly reflect the state of lake water quality, and mastering long-term and large-scale lake SD is the key to control and improve the lake water environment. Dianchi Lake, located in the middle of Yunnan Guizhou Plateau, is the sixth largest freshwater lake in China. It is the main water area for irrigation in Kunming area, and it is also the basic condition for urban development. Therefore, Dianchi Lake is chosen as the research area. Because the in-situ monitoring of lake water quality for this study area was started late, there are few historical SD data. So, it is necessary to simulate and estimate SD by remote sensing images. In this paper, deep neural network algorithm was used to invert the SD of Dianchi Lake from January 1, 2001 to December 31, 2018 based on in-situ data and MODIS remote sensing images, and explored its spatial-temporal variation characteristics by geospatial analysis. The in-situ data was the daily monitoring values of 10 stations (Baiyukou, Caohai Center, Dianchi South, Duanqiao, Guanyinshan East, Guanyinshan West, Guanyinshan Center, Haikou West, Huiwan Center, and Luojiaying) from 2001 to 2010 and the monthly monitoring values of 2 regions (Caohai and Waihai) from 2018, which was provided by Yunnan Academy of Environmental Sciences; MODIS data was provided by NASA LAADS Web, with daily time resolution and 500 m spatial resolution. The methods used in this paper included Grey Relational Analysis (GRA), Long-Short Term Memory (LSTM), and Theil-Sen slope estimation. In the construction of SD inversion estimation model, the main methods include Correlation Analysis (C), Outlier Processing (O), Denoising Processing (D), and estimation model (COD-LSTM). The results showed that (1) the inversion model proposed in this paper had better performance (RMSE=0.1359, MAE=0.1134), which can objectively reflect SD status. (2) The analysis of temporal variation characteristics indicated that the SD of Dianchi Lake presented a downward trend with an average comprehensive change rate of -0.08 m/10 a. (3) The analysis of spatial variation characteristics indicated that the rate of decline in the region with higher SD was larger, and the trend in the region with lower SD was relatively stable. The SD near the urban and residential areas was relatively low. Human activities would become an important factor affecting the SD changes in Dianchi Lake, and it was also the main factor causing lake pollution.

Ecological Risk Assessment of Typical Plateau Lakes

Plateau lakes have significant ecological value. With economic development, lake pollution and ecological degradation have become increasingly prominent. There are many ecological risk assessment methods. This article combines four different ecological risk assessment methods including single-factor pollution index, geological accumulation index method, potential risk index method, and pollution load index method to analyze the heavy metal pollution in Yangzong seabed mud as comprehensively as possible. It shows that the results obtained by different ecological risk assessment methods are slightly different. The overall trends of the geological pollution index and the single-factor pollution index are similar. In terms of time, except for the two elements of mercury and cadmium, the contents of other heavy metals in 2019 are lower than in 2018, indicating that heavy metal pollution has decreased in 2019; from the perspective of spatial distribution, In 2018, the overall pollution level on the south side of Yangzonghai was higher than that in the central and northern regions of Yangzonghai . On the whole, whether it is the potential risk index or the appropriate pollution load index, the pollution level on the south side of Yangzonghai is higher than that in the central and northern areas of Yangzonghai, and the northern area has the least pollution.

Metallic trace elements contained in the sediments of Dayet Er-Roumi Lake (Morocco)

The contamination of aquatic ecosystems with metals remains a serious environmental problem of growing concern. Sediments are often studied as reservoirs or wells for many chemical pollutants. They are micropollutant traps; they also indicate the watercourse's historical pollution, lagoons, and lakes…Lake Dayet Er-Roumi (SIBE) is the only permanent natural lake in the Khemisset region (Morocco); this wetland is affected by several forms of pollution that are mainly linked to human activities (agricultural, domestic, industrial, etc.). The objective of our study is to contribute, through qualitative and quantitative analysis, to the assessment of lake sediment pollution by Spatio-temporal monitoring of certain toxic heavy metals such as Mn, Zn, Cr, Cd. These sediments are collected on the level of the lake's surface; the concentration of heavy metals was measured by microwave plasma atomic emission spectroscope (MP-AES). Metal analyses carried out at three measuring points during the winter season reveal a high concentration of Zn, Cr, and Mn at all stations during the winter season, which far exceeds the recommended standards, with a low level of Cd. The contamination factor "FC" and the degree of contamination "DC" reveal polymetallic contaminations dominated by two elements, zinc, and Chromium, which are the most worrying. These results clearly show that lake Dayet Er-Roumi is polluted; strategies to limit the lake's pollution must be implemented to avoid several ecological problems (fish mortality, etc.).