Metals In Lake Sediments Research Articles

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.

Monitoring the Centennial Variation of Heavy Metals in Lake Sediments and Influencing Factors Using Environmental Magnetism and Machine Learning Methods

The association between the magnetic properties of lake sediments and heavy metal(loid)s (HMs) is well-documented; however, their correlation with the chemical fractions of HMs remains under-investigated. Developing a robust workflow for predicting HMs risk utilizing various machine learning techniques in conjunction with magnetic analysis presents a complex challenge. This study assessed the predictive efficacy of nine machine learning models for determining the chemical fractions of HMs, employing magnetic parameters derived from sediment cores in a large, shallow lake. These models encompassed random forest, support vector machine, relevance vector machine, extreme gradient boosting, principal component regression, multivariate adaptive regression splines, gradient boosting with component-wise linear models, and lasso and elastic-net regularized generalized linear models. The support vector machine model demonstrated superior performance, achieving coefficient of determination values surpassing 0.8 in both training and testing phases. Through interpretable machine learning approaches, key drivers of HMs were identified among magnetic and physicochemical indicators. Magnetic susceptibility values, high coercivity remanent magnetization, ratios of anhysteretic remanent magnetization to magnetic susceptibility, and anhysteretic remanent magnetization to saturation isothermal remanent magnetization within specific ranges exhibited a positive correlation with Cd, Hg, and Sb. This research significantly advances our understanding of HMs risk assessment in lake sediments by leveraging accessible magnetic measurements within an interpretable machine learning framework.

Heavy Metals in Sediments of Subarctic Meromictic Lakes of the White Sea as Possible Tracers of Environmental Changes

Meromictic lakes of the marine coast, quite widely distributed in the northern hemisphere, are the result of climate changes and glacier retreat. The bottom sediments of these lakes serve as a geological chronicle of the history of marine basin’s development with the geochemical occurrence forms of elements indicate various processes of their accumulation. This paper presents research results concerning the occurrence of forms of heavy metals in lake sediments along the coast of the White Sea. These results are based on a sequential seven step leaching procedure, followed by ICP-MS analysis and subsequent statistical data processing. To determine differences among the examined geochemical parameters, Pearson’s correlation analysis and Ward’s cluster analysis were utilized. The total content of Cr, Mn, Fe, Co, Ni, Zn, V, and Pb in the sediments did not exhibit significant differences based on their degree of isolation from the sea. The major contribution to deposition of these metals in sediments of the meromictic lakes studied is the residual form, encompassing the mineral matrix of the sediment. At the same time, the elevation of mobile forms for all the metals examined corresponds to an increase in the isolation of lakes from the White Sea. In the meromictic lake sediments, concentrations of Cu, Mo, and U demonstrated significant increases in forms tightly bound to organic matter, while Cd exhibited an association with Fe-Mn oxyhydroxides. Notably, a significant difference in the occurrence forms of Cu, Cd, Mo, and U was evident in the reduced sediments of meromictic lakes when compared to those of open sea bays. The meromictic lakes along the White Sea coast, positioned at various stages of isolation, hold promise for investigating the migration of metals in response to environmental changes.

Uncertainties in Pollution and Risk Assessments of Heavy Metals in Lake Sediments Using Regional Background Soils in China.

Background soils are frequently utilized as a surrogate to assess pollution levels and environmental risks of heavy metals in Chinese lakes. However, there remains a lack of understanding regarding the reliability and uncertainty of such assessments. Here, we determined heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) in sediment cores from five rural lakes in North China to evaluate the reliability and uncertainty of the assessments using background soils by comparing them with assessments based on background sediments. Comparative studies reveal large uncertainties in the assessments using background soils. Among these metals, uncertainties for Hg and Cd are relatively large, whereas those for the other metals are minor. This discrepancy is due to the considerably higher natural variability of Hg and Cd in soils and sediments in comparison to the other metals. Generally, assessments utilizing background soils underestimate pollution levels and risks of Hg but overestimate those of Cd in these lakes. Despite limited human activities around the lakes, they still received a considerable influx of heavy metals via regional atmospheric transport. Assessments of the nine metals indicate moderate to considerable ecological risks in these lakes. The risks are contributed primarily (78-89%) by Hg and Cd. This study underscores the substantial uncertainties in assessing heavy metal pollution and risks using regional background soils and emphasizes the importance of controlling atmospheric emissions of Hg and Cd to mitigate pollution in rural and remote water bodies in China.

Ecological risk characteristics of sediment-bound heavy metals in large shallow lakes for aquatic organisms: The case of Taihu Lake, China

Heavy metal contamination in the surface sediments of large shallow lakes in China is becoming increasingly serious. However, more attention has been paid to the human health risk of heavy metals in the past, while little consideration has been given to aquatic organisms. Taking Taihu Lake as an example, we explored the spatial and temporal heterogeneity of the potential ecological risks of seven heavy metals (Cd, As, Cu, Pb, Cr, Ni, and Zn) to species at different taxonomic scales using an improved species sensitivity distribution (SSD) method. The results showed that all six heavy metals, except Cr, were exceeded to some extent compared to background levels, with Cd being the most severe exceedance. Based on the hazardous concentration for 5% of the species (HC5), Cd had the lowest HC5 value, implying the highest ecological risk of toxicity. Ni and Pb had the highest HC5 values and the lowest risk. Cu, Cr, As and Zn were at a relatively moderate levels. For the different groups of aquatic organisms, the ecological risk of most heavy metals was generally lower for vertebrates than for the whole species. The risk for invertebrates and algae was higher than that for all species. Zn and Cu had the highest potentially affected fractions (PAFs) for all classification cases, with mean PAFs of 30.25% and 47.2%, respectively. Spatially, the high ecological risk of sediment heavy metals was significantly related to the spatial characteristics of the type and intensity of human activities in the catchment. Administratively, the environmental quality standards for freshwater sediments proposed by America and Canada are insufficient to protected against the ecological risks of heavy metals in Taihu Lake. In the absence of such standards, China urgently needs to establish an approptiate system of environmental quality standards for heavy metals in lake sediments.

Metals in Lake Sediments as Indicators of Human Activities in Prehistory: Case Study of the Southeastern Baltic, Kamyshovoe Lake

This paper presents the results of geochemical research on the Kamyshovoe Lake sediments (Kaliningrad oblast, Russian Federation). The study of Pb, Ni, Zn, As, Co and Cu concentration and enrichment factors (EF) combined with the results of the lithological, geochronological, magnetic susceptibility and microcharcoal studies revealed possible anthropogenic sources of metals in southeastern Baltic lake sediments from the Neolithic to the Medieval period. Increasing Co EF value and peaks of the Pb EF in Kamyshovoe Lake sediments, starting from ~6000 cal yr BP in the Neolithic, probably show the growing role and usage of metals as dyes and fixatives. Since ~3100 cal yr BP, in the end of the Bronze Age, a simultaneous increase in the content of indicators of metallurgical production Pb, Ni, Zn and As, coinciding with growth of the microcharcoal curve, can show a growing demand for metal objects in the southeastern Baltic region and the input of the local or regional ancient metallurgy into the metal pollution of the lake sediments.

Potential ecological risk quantification of metals in lake sediments: a considering of sources

Potential ecological risk quantification of metals in lake sediments: a considering of sources

Potential ecological risk quantification of metals in lake sediments: a considering of sources

Potential ecological risk quantification of metals in lake sediments: a considering of sources

Ecological risk of heavy metals in lake sediments of China: A national-scale integrated analysis

Intensive anthropogenic activities, specifically, industrial and agricultural production, have resulted in heavy metal enrichment in lake sediment and threats to aquatic ecosystems and human health. Evaluating the potential ecological risk of heavy metals in lake sediment is essential for promoting appropriate lake management in aquatic ecosystems. Large-spatial scale risk evaluations of heavy metal pollution in lake sediment in densely populated countries such as China are lacking. We compiled sediment heavy metal (Cu, Pb, Zn, Ni, Cr, As, Hg, and Cd) data from 190 lakes distributed across five geographic zones in China published between 2000 and 2019, evaluated the potential ecological risk and identified heavy metal sources through positive matrix factorization. Five conclusions were drawn. (1) Regarding the eight collected heavy metals, 6.1–40.4% of 190 lakes exhibited higher concentrations than the Chinese soil background value, and the concentration in 6.2% of lakes exceeded the probable effect concentration. (2) Based on the potential ecological risk index (PERI) and sum of toxic units (STU), Cd and Hg were the major pollutants. (3) The PERI value notably decreased with increasing lake surface area, and small lakes (<10 km2) generally yielded high PERI values. Among the five Chinese geographic zones, the Eastern Plain Lake Zone and Inner Mongolia-Xinjiang Lake Zone exhibited higher potential ecological risk. Compared to natural lakes, urban lakes and reservoirs posed higher ecological risks, while freshwater lakes yielded higher PERI values than saltwater lakes and saline lakes. (4) In all lakes, lake sediment pollutants Cu and Zn mainly originated from traffic sources; Cd originated from agricultural activities; Pb and Hg were related to industrial activities; and Ni, Cr and As indicated mixed sources. (5) In the Eastern Plain Lake Zone, Yunnan-Guizhou Plateau Lake Zone and Northeast Plain and Mountain Lake Zone, industry was the dominant source of heavy metals in lake sediment, while in the Tibetan Plateau Lake Zone and Inner Mongolia-Xinjiang Lake Zone, except for industrial sources, agricultural sources played an important role. Our national-scale integrated analysis provides valuable references for both macroscale policy formulation and polluted lake restoration.

Spatial distribution, source identification and ecological risk assessment of POPs and heavy metals in lake sediments of Istanbul, Turkey

Istanbul needs to be protected and constantly monitored water resources due to its increasing population and the decrease in precipitation. This study aims to comprehensively reveal surface sediments collected from reservoirs that supply water to Istanbul concerning POPs (PAHs, PCBs, and OCPs) and heavy metals; to identify possible sources of PAHs, and conduct their ecological risk assessment. Pollution indices in this study were used as contamination degree (CD) contamination factor (CF), geoaccumulation index (Igeo), pollution load index (PLI) and Sediment Quality Guidelines (SQGs). Total PAH concentrations of surface sediments at the sampling points ranged from 46.29 ng/g (A7) to 403.9 ng/g (A15). Benzo(b)fluoranthene (5.647–59.42 ng/g), Pyrene (3.625–83.10 ng/g), Fluoranthene (3.363–66.48 ng/g), Phenanthrene (3.115–52.48 ng/g), Chrysene (3.532–43.98 ng/g), Naphthalene (6.606–36.20 ng/g), Benzo(g,h,i)perylene (3.316–41.73 ng/g) and Indeno(1,2,3-c,d)pyrene (3.453–38.84 ng/g) are the dominant PAH compounds. PAH pollution may be caused by the village-town settlements near the dam and the O7-D020 highway. Total OCP concentration ranged from 2.233 ng/g (A12) to 7.337 ng/g (A1), while total PCB concentration ranged from 0.246 ng/g (A13) to 3.708 ng/g (A1). The lowest total OCP and PCB concentrations were found in surface sediments taken from Kazandere, Papuçdere and Alibey Dam lakes. DDT p,p (0.072–5.177 ng/g) has the highest concentration among all sediment samples. While the most dominant OCP compounds in the samples were DDT p,p, DDE p,p and DDD p,p, HCH alpha, HCH beta, respectively, PCB 153, 138 and 180 were the highest detected PCB congeners in the same samples. Total heavy metal concentration varied from 77,812 mg/kg to 267,072 mg/kg. According to PAH diagnostic analysis, the surface sediments of Terkos, Büyükçekmece, Elmalı, Darlık, Sazlıdere, Alibey and Ömerli Dams were polluted by petrogenic sources, while the surface sediments of Kazandere and Papuçdere Dams were affected by pyrogenic sources. None of the levels of POPs in the samples exceeded the ERM values. Slight and moderate contamination of heavy metals, such as Pb and Zn, were present in most of the sampling points according to CD, CF, PLI and Igeo values. The quality criteria of heavy metals showed that almost all of the sampling points had Cd, Pb and Hg concentrations below the ERL values. The Ni concentrations at most of the sampling points significantly exceeded the ERM values. The concentrations of As, Cr, Cu and especially Ni and Zn exhibit a significant toxic risk to aquatic organisms to sediment quality criteria.

Heavy metal contamination in surface sediments from lakes and their surrounding topsoils of China.

Due to rapid urbanization, industrialization, agricultural development, and mining activities, soil heavy metal pollution has become a severe issue in China. To explore the regional heavy metal ecological risk of lake sediment and surrounding topsoil, we analyzed 237 lakes, with 1797 lake sediment sampling points and 1164 surrounding topsoil sampling points. Lower mean concentrations were detected for most heavy metals in soils than sediment (except for Hg). Cd and Hg in sediments and soils showed a more significant variation, with the coefficient of variation exceeding 110%. Linear regressions and Pearson's correlation analyses demonstrated that sediments and soils exhibited significant positive correlations. The principal heavy metals exceeding the Agricultural Soil Control Standard (ASCS) in sediments and soils were As and Cd, respectively. The Yunnan-Guizhou Plateau Lake Region (YGPLR) was the most seriously affected, exceeding the ASCS for Cd. The lakes with the most severe pollution were located in YGPLR impacted by the high background concentration of heavy metals in soil and mineral development activities. The Eastern Plain Lake Region, the Southeast Lake Region, and the Northeast Plain and Mountain Lake Region showed a clear anthropogenic impact. Lakes in the Inner Mongolia-Xinjiang Lake Region and the Tibetan Plateau Lake Region were estimated to have relatively low ecological risks due to their sparse population and slight environmental disturbance. The impact of geochemical factors on the ecological risk of heavy metals in lake sediments is more substantial than that of human activities at the regional scale.

Biogeochemical cycling of heavy metals in lake sediments: impact of multispecies diffusion and electrostatic effects

Fate and transport of heavy metals is controlled by the biogeochemical processes in the environment. Reactive transport modeling is particularly important for capturing the complex interplay between the microbial community dynamics and redox-stratified environments. The focus of this study is to investigate the impacts of (i) multicomponent diffusion (MCD) and (ii) electrical double layer (EDL) on reactive diffusive transport of heavy metals at Lake Coeur d’Alene (LCdA) sediments. The solute benthic fluxes at LCdA sediments are controlled by diffusion, and therefore, the biogeochemical model is focused purely on diffusive transport. In diffusive transport-dominated multicomponent systems, species-specific multicomponent diffusion (i.e., Nernst-Planck representation of diffusion) and the explicit treatment of electrostatic effects can play an important role on the overall dynamics of biogeochemical cycling of metals in the system. The results of this study demonstrate that the use of single uniform diffusion coefficient for all species in purely diffusion-dominated sediments may underestimate the mobility of heavy metals undergoing complex reaction network. This outcome is further signified when explicit treatment of EDL effects is considered in addition to MCD. The simulation results also illustrate the importance of aqueous metal (bi)sulfide complexes, especially when MCD and EDL effects are implemented in reactive transport simulations, impacting the solubility and dynamics of heavy metals in diffusion-dominated systems. The competitive effects of Fe-reducing bacteria FRB and sulfate reducing bacteria SRB activities on pH and overall biogeochemical processes are also demonstrated with multispecies diffusion and explicit treatment of electrostatic effects in the system.

Targeting Remediation Dredging by Ecological Risk Assessment of Heavy Metals in Lake Sediment: A Case Study of Shitang Lake, China

Understanding the spatial distribution and pollution characteristics of heavy metals in lake sediment is crucial for studying deposition and migration processes, assessing lake conditions, and determining the extent of remediation dredging. The present work is a case study of heavy metal pollution in Shitang Lake in Anhui province, China. Heavy metal concentrations were determined in sediment at locations across the lake to a depth of 100 cm, and pollution levels were assessed on the basis of the Geoaccumulation Index (Igeo) and Potential Ecological Risk Index (RI). Hg and Cd were the predominant heavy metals in the sediment, and the Igeo and RI indicated high pollution levels in the northern and southern zones of the lake. These findings can be used to guide the prioritization of dredging operations.

Distribution, pollution status, and source apportionment of trace metals in lake sediments under the influence of the South-to-North Water Transfer Project, China

In an effort to combat the threat of drought, China constructed the South-to-North Water Transfer Project (SNWTP), the biggest water transfer project in terms of volume with the largest beneficiary population in the world. Reports have shown that massive water diversion projects have had detrimental environmental consequences including water quality decline and freshwater habitat degradation. However, few reports have assessed the impact of the transfer project on sediment quality, which is highly susceptible to allogenic and local anthropogenic pollution. We examined the distribution characteristics of Cd, Cr, Cu, Ni, Pb and Zn in surface sediment of the largest reservoir along the East Route of SNWTP, Nansihu Lake, followed by positive matrix factorization (PMF) to determine their potential sources. We utilized enrichment factor, multiple sediment quality guidelines (SQGs), and potential ecological risk index (RI) to determine metal accumulation or pollution risk. The results show the mean concentrations of Cr, Cu, Pb, Zn were slightly lower than in samples collected in 2003, 2010 and 2012, while the mean concentrations of Cr and Ni were significantly higher than samples from previous years. Among the six metals, Cr, Cu and Ni are of higher ecological risk according to SQGs; but Cd is of higher ecological risk according to RI. PMF analysis shows that industrial production and shipping are important sources of Cr, Cu, and Ni. PMF analysis also shows that a considerable amount of trace metals, especially Cd, Cr, Pb and Zn, mainly comes from the use of pesticide fertilizers and biomass sources in farmland, and may partly enter Nansihu Lake from SNWTP. This study reveals the possible sources of trace metals to the Nansihu Lake which is part of SNWTP; the results of the study may serve as a reference for better understanding the impact of future water diversion projects on metals distribution.

Molecular weight-dependent spectral and metal binding properties of sediment dissolved organic matter from different origins

The metal binding potential of dissolved organic matter (DOM) is highly related with its inherent properties such as molecular weight (MW). Here sediment DOMs with different origins, i.e., algae- and macrophyte-dominated sediment DOM (named as ASDOM and MSDOM, respectively), were size-fractionated into low MW (LMW-, <1 kDa) and high MW (HMW-, 1 kDa~0.45 μm) fractions, with the spectral and metal binding properties in different MW fractions exploring via total organic carbon, absorption spectroscopy, fluorescence parallel factor (PARAFAC) analysis, and Cu(II) titration techniques. The MSDOM contained more organic carbon, lower specific UV absorbance, lower fluorescence index, higher humification index, and lower biological index compared to the ASDOM. As for the MW-fractionated samples, the humic- and fulvic-like fluorophores were mainly distributed in the LMW-DOM, while the protein-like ones were located richly in the HMW-DOM. Thus, obvious MW- and origin-dependent heterogeneities in abundance and spectral properties were observed for sediment DOMs. One humic-like, one fulvic-like, and two protein-like fluorescent components were identified by PARAFAC analysis, with different components exhibiting different variable patterns in response to Cu(II) addition. Irrespective of sample sources, humic- and fulvic-like components had higher condition stability constants (logKM > 4.96) than protein-like components (logKM < 4.86). As for the MW-fractionated samples, the HMW-DOM, especially the HMW humic-/fulvic-like components, exhibited higher metal binding potential than the bulk and LMW counterparts. This study highlighted the importance of HMW-DOM in manipulating the behavior, fate, and bioavailability of heavy metals in lake sediments.

Geochemical baseline establishment and pollution source determination of heavy metals in lake sediments: A case study in Lihu Lake, China

Geochemical baseline, as the boundary between background and anomalous values of pollutants in sediments, is typically used to evaluate whether sediments are disturbed by human activities. However, this tool is rarely used in identifying the pollution source types of heavy metals. This study aims to determine the pollution source of heavy metals in sediments based on the geochemical baseline by using statistical methods. The geochemical baseline values of surface and core sediments in Lihu Lake, a typical urban lake in Taihu Lake Basin, were calculated by relative cumulative frequency and iterative methods. The enrichment degree and pollution source of heavy metals in surface sediments were also determined. The metal baselines in the core or surface sediments calculated by the two methods did not show significant difference (P > 0.05). The geochemical baseline of core sediments could represent the background level of sediments in the study area. The enrichment extent of the tested metals in surface sediments followed the order of: Pb > Zn > Hg > As > Cu > Cd > Ni > Cr. The average contents of Pb and Zn were 3.0 and 2.1 times of the background values, and their pollution were mainly derived from local and non-point sources, respectively. The contributions of the background concentrations to the contents of Cu, As, and Hg were slightly higher than that of human interference, and accounted for 59.4%, 58.4%, and 54.0% of the total contents, respectively. The pollutions of Cu and As mainly originated from non-point source, and that of Hg was mainly derived from local source. The contents of Cr, Ni, and Cd were within the background level. Geochemical baseline can be used not only to determine the enrichment degree but also as a potentially useful tool for identifying the pollution source (local and non-point source) of heavy metals in sediments.

Identification of anthropogenic inputs of trace metals in lake sediments using geochemical baseline and Pb isotopic composition

Source identification of trace metals in the water environment is important in understanding its environmental behavior and in the prevention and remediation of further pollution. Here, the regional geochemical baseline (RGB) and Pb isotopic ratios are combined to decipher the anthropogenic contribution rate, main anthropogenic source, and transport pathway of trace metals in sediments collected from the largest freshwater lake in northern China, Baiyangdian (BYD) Lake. The established RGB values of Cr, Ni, Cu, Zn, Cd, and Pb were 63.0, 27.8, 24.7, 46.1, 0.18, and 22.0 mg/kg, respectively, which were slightly different from the regional soil background values. Based on the RGB and actual concentrations of trace metals in the lake sediments, the calculated average anthropogenic contribution were lower than 20% except for Cd. Compared with the other trace metals, Cd was the element most impacted by anthropogenic input, which was mainly caused by the point source pollution in some sites. The risk assessment (geo-accumulation index and potential ecological risk) using the RGB as the regional background values showed that BYD sediments were uncontaminated by the trace metals, and at low ecological risk from the trace metals. The results of these two risk assessments further validated the assessment of the anthropogenic contribution by the RGB. In addition, Pb isotopic ratios result showed that coal combustion was the main potential source of anthropogenic Pb in the BYD sediments and atmospheric deposition was the main transport pathway. This study tried to combine the geochemical baseline and Pb isotopic composition to identify the anthropogenic input of trace metals in the sediments. It will provide a new insight into assessing the anthropogenic contributions, identifying the main anthropogenic sources, and transport pathways of trace metals in water environment.

Historical accumulation and ecological risk assessment of heavy metals in sediments of a drinking water lake.

Heavy metal contamination in sediments is progressively being recognized as a challenging problem in large parts of the developing world, particularly in Asian countries. A drinking water lake in Yunnan-Guizhou plateau, China named Hongfeng Lake was selected as the research target. Forty surface sediment samples and 4 sediment cores were collected to reveal the accumulation of heavy metals in the sediments of the lake. The mean concentrations of Cr, Cu, Pb, Cd, As, and Hg in surface sediments were 81.67, 45.61, 29.78, 0.53, 22.71, and 0.25mg/kg, respectively, which exceeded the background levels of sediment 1.1~3.3 times. The calculation of geoaccumulation (Igeo) and potential ecological risk (PER) index analysis were preformed, and the results showed a considerable risk for Cd and Hg on the whole. Spatially, the northern part showed a higher risk than the southern part and tributaries of the lake, and a moderate risk in the overall sediment of the lake. The historical level of heavy metals in Hongfeng Lake was traced by vertical sediments study and it was dated back approximately 35years. The EF trends of a feature sampling site HF8 showed strong temporal variations, and peaked in the year 1995. After that, the EFs exhibited a declining trend, which reflects productive environmental protection and management by the local government. For the Hongfeng Lake, a typical lake with heavy metal-contaminated sediments, the in-situ remediation technique could be a suitable method for its remediation.

Vertical and horizontal distribution, source identification, ecological and toxic risk assessment of heavy metals in sediments of Lake Aygır, Kars, Turkey

ABSTRACTSurface and core sediment samples were collected from Lake Aygır, Turkey, to determine heavy metal distribution, probable sources and potential ecological and toxic risks for the lake. Heavy metals, total sulfur, total phosphate, total organic carbon, chlorophyll degradation products, and CaCO3 content were established. The enrichment factor, PLI, potential ecological risk index, and toxic risk index were calculated. Zn was determined to have the highest accumulation in surface sediment, followed by Cr, Pb, and Cd, respectively. Cd was the only element that exceeded the critical value of 40 and posed a moderate potential ecological risk. According to TRI, no ecotoxic risk was found. It is thought that local fossil fuel consumption is responsible for the accumulation of heavy metals since there is a lack of urbanization, industrialization, and agricultural activities around the lake.

Multivariate geostatistical analysis and source identification of heavy metals in the sediment of Poyang Lake in China

Heavy metals in lake sediment have become a great concern because their remobilization has frequently occurred under hydrodynamic disturbance in shallow lakes. In this study, heavy metals (Cr, Cu, Cd, Pb, and Zn) concentrations in the surface and core sediments of the largest freshwater lake in China, Poyang Lake, were investigated. Geostatistical prediction maps of heavy metals distribution in the surface sediment were completed as well as further data mining. Based on the prediction maps, the ranges of Cr, Cu, Cd, Pb, and Zn concentrations in the surface sediments of the entire lake were 96.2–175.2, 38.3–127.6, 0.2–2.3, 22.5–77.4, and 72.3–254.4mg/kg, respectively. A self-organizing map (SOM) was applied to find the inner element relation of heavy metals in the sediment cores. K-means clustering of the self-organizing map was also completed to define the Euclidian distance of heavy metals in the sediment cores. The geoaccumulation index (Igeo) for Poyang Lake indicated a varying degree of heavy metal contamination in the surface sediment, especially for Cu. The heavy metal contamination in the sediment profiles had similar pollution levels as those of surface sediment, except for Cd. Correlation matrix mapping and principal component analysis (PCA) were used to support the idea that Cr, Pb, and Zn may be mainly derived from both lithogenic and human activities, such as atmospheric and river inflow transportation, whereas Cu and Cd may be mainly contributed from anthropogenic sources, such as mining activities and fertilizer application.