Metals In Lake Research Articles

Enrichment Characteristics, Risk Evaluation, and Source Apportionment of Heavy Metals in Wabu Lake of Yangtze River to Huaihe River Water Diversion Project

Wabu Lake serves as a crucial junction within the Yangtze River to Huai River Water Diversion Project （Yangtze-Chao Lake-Wabu Lake-Huai River）, where clarifying the status and risk levels of heavy metal contamination in the lake is crucial for the aquatic ecological safety along the route of the project. Surface water and sediment samples from 24 locations in Wabu Lake were collected and analyzed for the contents of heavy metals （As, Zn, Pb, Ni, Cu, Cr, Fe, and Cd）. Risk evaluation and source apportionment of heavy metals in the lake were conducted using the human risk assessment （HRA） model, sediment quality guidelines （SQGs）, and positive matrix factorization （PMF） method. The results showed that the average concentrations of heavy metals （except for Cd and Pb） in the surface water were lower than the class III limits of the surface water quality standard （GB 3838-2002）. The average concentration of heavy metals （As, Zn, Pb, Ni, Cu, Cr, Fe, and Cd） in interstitial water were lower than the Criteria Continuous Concentration （CCC） of the National Recommended Water Quality Criteria. The average contents of As, Zn, Pb, Ni, Cu, Cr, and Cd in the sediment exceeded the background values by factors of 1.78, 1.85, 1.42, 1.77, 1.41, 1.38, and 3.46, respectively. In addition, the heavy metals Pb, Cd, and Cr in the Wabu Lake water posed severe risks to human health, with the cancer risk （CR） value for Cr reaching 6.14×10-5. The sediment quality guidelines （SQGs） indicated that the probability of adverse effects on lakes by As, Ni, and Cr was relatively high. The spatial distribution of risk areas showed that the risk control zones for As, Cr, and Ni in Wabu Lake covered almost the entire lake area. The PMF analysis indicated that the primary sources of heavy metals in Wabu Lake were exogenous inputs from industrial, agricultural, and residential activities in surrounding areas, followed by endogenous pollution caused by enclosed aquaculture. The subsequent focus should be on the pollution of heavy metals Cr, Cd, and Pb in the overlying water of Wabu Lake as well as the sediment ecological safety of As, Cr, and Ni in the sediment.

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.

Spatial and Temporal Variations in Heavy Metals in Lake and Reservoir Sediments in China: A Pollution Status and Risk Assessment

Spatial and Temporal Variations in Heavy Metals in Lake and Reservoir Sediments in China: A Pollution Status and Risk Assessment

The interaction between nutrients and heavy metals in lakes and rivers entering lakes

This study investigated the conditions and modes of interaction between nutrients and heavy metals within river and lake environments under multivariate conditions. Nitrogen and phosphorus nutrients were categorized into dissolved phosphorus, inorganic phosphorus, dissolved nitrogen, ammonium nitrogen, and nitrate nitrogen based on their chemical composition. Their correlations with heavy metal elements were scrutinized utilizing Bayesian models. The results revealed the following: (1) A robust interrelationship was observed between sediment metals and soluble metals within lake sediments and water bodies. (2) In lake environments, the competition between metals was relatively weak, and the influence of environmental factors was variable, without discernible patterns. This phenomenon may be attributed to the low concentration of soluble metals in the overlying water in the absence of external inputs. (3) Competition between metals in river sediment was weaker than that in lakes. This may be attributed to the flow dynamics and velocity of rivers, coupled with their strong self-purification ability. (4) Dissolved phosphorus (DP) exhibited greater control over the direction of metal adsorption and desorption compared to inorganic phosphorus (IP). (5) Similarly, dissolved total nitrogen (DTN) exhibited greater control over the direction of metal adsorption and desorption in river sediments compared to total nitrogen (TN). (6) Nitrate (NO3–-N) and ammonium (NH4+-N) simultaneously controlled the adsorption and desorption directions of metals such as Cr, Mn, Ni, Zn, and Pb in river sediment, with the direction of metal action dependent on soil adsorption capacity. These findings provide valuable insights into the complex interactions shaping nutrient-metal dynamics in aquatic systems, offering potential avenues for enhanced environmental management and remediation strategies.

A study of environmental pollution and risk of heavy metals in the bottom water and sediment of the Chaohu Lake, China.

Most of the existing research for heavy metals in water at present is focusing on surface water. However, potential environmental risk of heavy metals in the bottom water of lakes cannot be ignored. In this study, the content, distribution, and speciation of nine heavy metals (As, V, Cr, Co, Ni, Cu, Zn, Cd, and Pb) in the bottom water and sediment of Chaohu Lake were studied. Some pollution assessment methods were used to evaluate the environmental effect of heavy metals. Positive matrix factorization was conducted to investigate the potential sources of heavy metals in sediment. The contents of heavy metals in the bottom water of Chaohu Lake mean that its environmental pollution can be ignored. In sediment, Cd and Zn have showed stronger ecological risk. pH and redox potential are more likely to affect the stability of heavy metals in the bottom water of Chaohu Lake during the dry reason. Industrial sources (16%) are no longer the largest source of heavy metal pollution; traffic sources (33.6%) and agricultural sources (23.4%) have become the main sources of pollution at present. This study can provide some support and suggestions for the treatment of heavy metals in lakes.

Fractionation and speciation of metals in lakes formed by abandoned clay pits from industrial effluents (Santa Gertrudes, São Paulo, Brazil) using the diffusive gradient in thin films (DGT) technique

Environmental impacts caused by mining activities (mainly tailings and effluents) are presenting serious challenges for humanity worldwide. In Brazil, clay extraction activities in the Ceramic District of Santa Gertrudes (CDSG) have led to the formation of abandoned drainage wells causing environmental and human health concerns. In the 90's, it was discovered that in one of the production areas, known as the region of the lakes of Santa Gertrudes, several ceramic industries had contaminated lakes created by abandoned clay pits with industrial effluents containing toxic metals. In the present study, analysis of total and dissolved concentrations of Al, Cd, Co, Cu, Mn, Ni, Pb and Zn in the waters of these lakes were combined with the diffusive gradients in thin films (DGT) technique to assess the lability and bioavailability of the target elements, representing one of the first studies to investigate the real environmental impact of contamination caused by ceramic production wastes to an aquatic system. Furthermore, based on the total concentrations and main physicochemical characteristics of each lake, a speciation analysis was performed using the MINTEQ software which data was compared with other surface water systems. The results indicated the presence of metals associated with ceramic residues in total, dissolved and labile fractions. It was verified that Zn, Ni and Cu were the only target metals found in labile form and according to speciation were present in the form of “free” ions, and thus may present risk in terms of bioavailability, although the majority of the total concentrations are within the limits established by the national environmental agency.

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.

Properties and metal binding behaviors of sediment dissolved organic matter (SDOM) in lakes with different trophic states along the Yangtze River Basin: A comparison and summary

The nature of sediment dissolved organic matter (SDOM) can reflect the environmental background, nutritional status and human activities and is an important part of lakes. The differences in the binding capacity of heavy metals and organic matter in lake sediments with different trophic states at the catchment scale and the mechanism of the differences in binding are still unclear. To solve this problem, we collected bulk SDOMs (< 0.7 μm) from 6 respective lakes (from upstream to downstream) in the Yangtze River Basin (YRB) to qualitatively and quantitatively characterize their properties and metal binding behaviors using excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-FARAFAC) and two-dimensional correlation spectroscopy of synchronous fluorescence spectroscopy and Fourier transform infrared spectroscopy (2D-SF-COS and 2D-FTIR-COS). The results showed that sediment dissolved organic carbon (SDOC) was mainly enriched in low molecular weight (LMW: < 1 kDa) fractions. The total fluorescence intensity (Fmax) of SDOM from upstream was larger than that from downstream (p = 0.033), and humic-like fluorophores were dominant in these lakes. The Fmax of sediment humic-like components (C1+C2) was closely related to the trophic levels of the lakes. Protein-like substances and oxygen-containing functional groups (C−OH, C=O, and C−O) were preferred in the reaction between SDOM and copper (Cu2+) or cadmium (Cd2+), while a unique binding path was exhibited in the moderately eutrophic DCL. In terms of fluorophore types, higher Cu2+-binding abilities (LogKCu) were observed in the humic-like matter for the lakes in the upper reaches and tryptophan-like matter for the lakes from the midstream and downstream areas of the YRB. Although Cd2+ complexed only with humic-like matter, LogKCd was higher than LogKCu. In terms of molecular weight (MW), the LogKCu/Cd of components were enhanced after MW fractionation. The HMW (0.7 μm – 1 kDa) components possessed higher LogKCu in most lakes (except for CHL and C4). The different fluorophores and molecular weight fractions in SDOM make an important contribution to reducing the ecological risks of heavy metals in lakes.

Multi-spectroscopic investigation of the molecular weight distribution and copper binding ability of dissolved organic matter in Dongping Lake, China

The properties and metal-binding abilities of dissolved organic matter (DOM) rely on its molecular weight (MW) structure. In this study, the spatial differences of DOM in compositions, MW structures, and binding mechanisms with copper (Cu2+) in Dongping Lake were investigated by applying excitation-emission matrix combining parallel factor analysis (EEM-PARAFAC), synchronous fluorescence (SF) spectra, two-dimensional correlation spectra (2D-COS), and Fourier transform infrared (FTIR) spectra. The EDOM for the entrance of the Dawen River and PDOM for the macrophyte-dominated region were divided from DOM of Dongping Lake based on hierarchical clustering analysis (HCA) and principal component analysis (PCA) and were size-fractioned into MW < 500 kDa and <100 kDa fractions. According to EEM-PARAFAC, Dongping Lake was dominated by tryptophan-like substances with MW < 500 kDa. The concentration of PDOM was higher than that of EDOM (p < 0.05). 2D-COS showed that protein-like components preceded humic-like components binding to Cu2+ regardless of sample type (215 nm > 285 nm > 310–360 nm). The Cu2+ binding capacity of DOM exhibited specific differences in space, components, and molecular weights. The humic-like component 1 (C1) and tryptophan-like component 4 (C4) of PDOM showed stronger binding abilities than those of EDOM. Endogenous tryptophan-like component 4 (C4) had a higher binding affinity for Cu2+ than humic-like components (logKa: C4 > C1 > C2) in PDOM irrespective of MW. Humic-like components with MW < 500 kDa displayed higher binding potentials for Cu2+. FTIR spectra showed that the main participants of DOM-Cu complexation included aromatic hydrocarbons, aliphatic groups, amide Ⅰ bands, and carboxyl functional groups. This study provides spatial-scale insights into the molecular weight structure of DOM in influencing the behavior, fate, and bioavailability of heavy metals in lakes.

Research on heavy metal release with suspended sediment in Taihu Lake under hydrodynamic condition.

Heavy metals are often stored in the sediment of lakes or reservoirs and are easily released to the overlying water in the case of strong wind, which greatly affects the water environment of lakes or reservoirs. The conventional investigation of heavy metals in lakes has been relatively extensive, but there is no numerical model for heavy metals released into overlying water with suspended sediment under hydrodynamic action. In this paper, laboratory experiments were carried out, and it is found that the concentration of heavy metals (Cr, Cu, Cd) often begins to stabilize after the concentration of total suspended solids (TSS) reaches a stable level. With the increase of flow velocity (3.2 to 14cm/s), the final equilibrium concentration of TSS, Cr, Cu, and Cd will also increase from 174 to 1102mg/L, 0.72 to 1.14μg/L, 2.34 to 10.45μg/L, and 0.13 to 0.35μg/L, respectively. Based on lattice Boltzmann method (LBM), a numerical model of heavy metal released into overlying water under hydrodynamic conditions is established. Compared the simulated data with measured data, the average [Formula: see text] of LBM model can be reached at 0.827, higher than 0.711 of traditional simulation model. The development of the numerical model is conducive to the prediction of lake or reservoir environment and also provides a theoretical basis for heavy metal treatment in reservoirs.

The potential ecological risks and bioavailability of heavy metals in the sediments of Lake Baiyangdian

沉积物是湖泊水体重金属的主要汇集场所，也是湖泊重金属污染研究及整治的重点.本文分析了白洋淀多个淀区沉积物中16种重金属含量水平及垂向分布特征，解析了其中典型有害重金属潜在生态风险，并基于酸可挥发性硫（AVS）及同步可提取金属（SEM）、间隙水溶解态金属、可转化态金属形态分级等研究，对重金属生物可利用性进行了分析.结果表明：沉积物重金属含量均值高低依次为Fe （29630.50 mg/kg）>Ti （3213.07 mg/kg）>Mn （539.44 mg/kg）>Zn （104.01 mg/kg）>V （76.63 mg/kg）>Cr （52.60 mg/kg）>Cu （43.49 mg/kg）>Ni （35.83 mg/kg）>Pb （26.75 mg/kg）>Co （10.32 mg/kg）>As （8.96 mg/kg）>Mo （2.06 mg/kg）>Sb （1.57 mg/kg）>Tl （0.43 mg/kg）>Cd （0.31 mg/kg）>Hg （0.16 mg/kg）；其中，10种重金属在各淀区沉积物中呈现出自北往南逐渐降低的趋势，各金属在不同淀区分布差异性主要由污染输入所致.除北部烧车淀区域外，其余区域重金属潜在生态风险总体处于较低水平.重金属污染主要来源于该区域周边河道，但近10年来污染输入及在沉积物中的富集总体趋于稳定并呈逐渐降低的趋势.入淀污染不仅增加了该区域沉积物中重金属总量，也使得其中可转化态重金属比例较高，大多在30%~90%之间，提升了重金属生物可利用潜力.水生植物等内生性有机质的大量富集导致沉积物还原性较强，AVS含量较高，沉积物中AVS和ΣSEM均值分别为（10.59±6.37）和（2.23±1.53）μmol/g （dw）.Cd、Cu、Ni、Pb、Zn等金属由于高含量还原态硫的固定而生物可利用性较低.然而，As和Hg在这样的高有机质和强还原环境下更容易溶解和释放，是潜在生物可利用性相对较高的金属，在间隙水中的浓度分别达到（17.07±0.23）和（2.39±0.94）μg/L，未来研究及整治中应给予更多关注.;Being the primary sink for heavy metals in lakes, the sediment is the hotspot for the research and remediation of heavy metals in lakes. In the current study, the horizontal and vertical distributions of 16 kinds of heavy metals in the sediment of multiple areas in Lake Baiyangdian were analyzed and based on the concentrations of several typical harmful heavy metals in the sediment, the potential ecological risk was assessed. The bioavailability of heavy metals was further analyzed according to the acid volatile sulfide (AVS), simultaneously extracted metals (SEM), dissolved metals in the pore water, and fractionation of mobile metals. The results showed that the concentrations of heavy metals in the sediment followed the descending order of:Fe (29630.50 mg/kg)>Ti (3213.07 mg/kg)>Mn (539.44 mg/kg)>Zn (104.01 mg/kg)>V (76.63 mg/kg)>Cr (52.60 mg/kg)>Cu (43.49 mg/kg)>Ni (35.83 mg/kg)>Pb (26.75 mg/kg)>Co (10.32 mg/kg)>As (8.96 mg/kg)>Mo (2.06 mg/kg)>Sb (1.57 mg/kg) >Tl (0.43 mg/kg)>Cd (0.31 mg/kg)>Hg (0.16 mg/kg). Among all the heavy metals studied, 10 kinds of the metals in the sediment of the studied areas showed a gradually decreasing trend from north to south of the lake. The variations in the horizontal distribution of metals between different areas were most likely caused by the external pollution input from the north part of the lake. The potential ecological risks of heavy metals in most parts of the lake were generally at low levels except for the Shaochedian area in the north. The inflowing rivers around this area were the main sources of heavy metal pollution. While the pollution input and the accumulation of heavy metals in the sediment have generally stabilized and gradually decreased during the past 10 years, the pollution input not only increased the total amount of heavy metals in the sediment of this area but also led to the high proportion of mobile heavy metals (mostly between 30% and 90%), which increased the bioavailable potential of metals. The massive enrichment of endogenous organic matter from the wither of aquatic plants led to the strong reductive status of the sediment, which thereby resulted in high concentrations of AVS. The average concentrations of AVS and ΣSEM in the sediment of the whole lake were (10.59±6.37) μmol/g(dw) and (2.23±1.53) μmol/g(dw), respectively. Due to the immobilization with a high concentration of sulfides, the bioavailability of Cd, Cu, Ni, Pb, and Zn were generally low. However, As and Hg are much easier to dissolve and release from the sediment under such high organic matter content and strong reducing environment. These two metals had relatively high potential bioavailability with the concentration in the pore water reaching (17.07±0.23)μg/L and (2.39±0.94)μg/L, respectively, which should be given more attention during future research and remediation works.

A Food-Safety Risk Assessment of Mercury, Lead and Cadmium in Fish Recreationally Caught from Three Lakes in Poland.

Simple SummaryThe research aimed to determine the content of lead (Pb), cadmium (Cd), and mercury (Hg) in water, sediment, and freshwater fish species roach (Rutilus rutilus), perch (Perca fluviatilis), and pike (Esox lucius) from the Dratów, Syczyńskie, and Czarne Sosnowickie lakes located on Polesie Lubelskie, Poland, as well as a food safety assessment for the consumer. Pb and Cd were measured by graphite furnace atomic absorption spectrometry, while Hg was measured by cold vapor atomic absorption spectrometry. The research results showed that both the waters and the sediments of the studied lakes are characterised by a low concentration of Pb, Cd, and Hg, which indicates the lack of a moderate influence of anthropopressure on these reservoirs. The range of heavy metal contents in the muscles of roach, pike, and perch for Pb was 0.0399–0.1595, 0.0305–0.0920, and 0.0296–0.1057 mg kg−1, respectively; for Cd 0.0014–0.0095, 0.0010–0.0015, and 0.0020 mg kg−1, respectively; and for Hg 0.0123–0.0499, 0.0185–0.0255, and 0.0216–0.0583 mg kg−1, respectively. The content of heavy metals in fish muscles was low and conformed to requirements as defined in the European Union (EU) food legislation. The health risk assessment with regard to the heavy metal contents in the muscles of fish confirmed the safety of this food for consumers.Heavy metals are introduced into water due to anthropogenic activities and can significantly affect an entire ecosystem. Due to their close integration with the water environment, fish are a sensitive indicator of contamination. In addition, fish is an important element in human diets, therefore, monitoring the concentrations of metallic contaminants in their meat is particularly important for food safety. This study aimed to assess the pollution of water ecosystems with selected toxic heavy metals in lakes Dratów, Czarne Sosnowickie, and Syczyńskie. The concentration of Pb, Cd, and Hg in water, sediment, and freshwater fish muscle tissue was determined, and a food safety assessment was performed. The analysis of water and sediments showed that the sediments were characterised by a significantly higher concentration of heavy metals. Presumably, this ecosystem element plays an important role in the uptake of heavy metal contaminants by fish whose levels were higher in planktonophagous and benthophagous fish species as compared to predatory fish. The food safety assessment showed that amounts of heavy metals in the muscle tissue posed no threat to the health of consumers ingesting that fish species, neither individually (THQ) nor collectively (TTHQ).

A historical record of trace metal deposition in northeastern Qinghai-Tibetan Plateau for the last two centuries.

Owing to rapid socio-economic development in China, trace metal emissions have increased and lakes even in remote areas have experienced marked changes in the last century. However, there are limited studies revealing long-term trends, anthropogenic fluxes, and spatial characteristics of trace metals in lakes. In this study, we present a geochemical record from Lake Qinghai in the northeastern Qinghai-Tibetan Plateau and reconstruct trace metal pollution history during the last two centuries. The lacustrine sediment core was dated by 137Cs and 210Pb, and sediments deposited prior to the 1850s were selected as the pre-industrial background. Factor analysis and enrichment factor indicated Cr, Cu, and Ni generally originated from natural sources, while Cd, Pb, and Zn have been influenced by human contamination since the mid-1980s. The anthropogenic Cd mainly derived from non-ferrous metal smelting in Gansu Province, and fluxes to Lake Qinghai sharply increased after the mid-1980s. The metal reconstruction is similar to other lake sediment records from China and corresponds well with rapid economic development in China. The spatial pattern of anthropogenic Cd fluxes to lakes is primarily attributed to regional industrial emission, phosphate fertilizers, and manure applied in agriculture.

Application of artificial substrate samplers to assess enrichment of metals of concern by river floodwaters to lakes across the Peace-Athabasca Delta

Study regionPeace-Athabasca Delta (PAD), northeastern Alberta. Study focusPotential for downstream delivery of contaminants via Athabasca River floodwaters to lakes of the PAD has raised local to international concern. Here, we quantify enrichment of eight metals (Be, Cd, Cr, Cu, Ni, Pb, V, Zn) in aquatic biota, relative to sediment-based pre-industrial baselines, via analysis of biofilm-sediment mixtures accrued on artificial substrate samplers deployed during summers of 2017 and 2018 in > 40 lakes. Widespread flooding in the southern portion of the delta in spring 2018 allows for assessment of metal enrichment by Athabasca River floodwaters. New hydrological insightsRiver floodwaters are not implicated as a pathway of metal enrichment to biofilm-sediment mixtures in PAD lakes from upstream sources. MANOVA tests revealed no significant difference in residual concentrations of all eight metals in lakes that did not flood versus lakes that flooded during one or both study years. Also, no enrichment was detected for concentrations of biologically inert metals (Be, Cr, Pb) and those related to oil-sands development (Ni, V). Enrichment of Cd, Cu, and Zn at non-flooded lakes, however, suggests uptake of biologically active metals complicates comparisons of organic-rich biofilm-sediment mixtures to sediment-derived baselines for these metals. Results demonstrate that this novel approach could be adopted for lake monitoring within the federal Action Plan.

Promotion and Mechanisms of DOM on Copper Adsorption by Suspended Sediment Particles

The adsorption of heavy metals by suspended sediment particles is a key process in the migration of heavy metals in lakes and is affected by various environmental conditions. To reveal the effects and mechanisms of dissolved organic matter (DOM) on the adsorption of copper ions by suspended sediment particles, a Cu(Ⅱ) adsorption test was conducted through a laboratory simulation test. The results showed that DOM promoted the adsorption of Cu(Ⅱ) onto the suspended particles. Under the respective influences of fulvic acid and DOM extracted from the sediment of the Xiangjiang River, the adsorption percentage of Cu(Ⅱ) increased from 71.51% to 75.31% and 85.69%. Scanning electron microscope-energy spectroscopy results showed that under the influence of DOM, Cu(Ⅱ) existed inside the sediment particles after being adsorbed. The results of UV-visible (UV-Vis) spectroscopy showed that Cu(Ⅱ) and DOM were first complexed and then dissociated during the adsorption reaction. The results of fluorescent excitation-emission matrix spectroscopy combined with parallel factor analysis and synchronous fluorescence spectroscopy combined with two-dimensional correlation analysis indicate that protein-like components promoted the adsorption of Cu(Ⅱ) onto the sediment suspended particles. In particular, tyrosine-like components played a critical role in promoting adsorption. However, humic-like components hardly promote this adsorption. This study has improved the theory of heavy metal migration in lakes and can be used as a basis for the prevention and control of heavy metal pollution in sediments.

Phosphate hinders the complexation of dissolved organic matter with copper in lake waters.

The properties of phosphate in lakes and their ability to cause eutrophication have been well studied; however, the effects of phosphate on the environmental behavior of other substances in lakes have been ignored. Dissolved organic matter (DOM) and heavy metals may coexist with phosphate in lakes. Herein, the mechanisms underlying the influence of phosphate on heavy metals complexation with DOM were investigated using multi-spectroscopic tools. Overall, the amount of DOM-bound Cu(Ⅱ) decreased with the increasing phosphate content. Furthermore, the fluorescence excitation and emission matrix results combined with parallel factor analysis showed that when the Cu(Ⅱ) concentration increased from 0 to 5mg/L and 50μM phosphate to the reaction of DOM and copper, the fluorescence intensity of tyrosine (component 1), humic-like (component 2) and tryptophan (component 3) decreased by 36.46%, 57.34%, and 74.70% compared with the treatment with no phosphate addition, respectively. This finding indicates that the binding of different fluorescent components to Cu(Ⅱ) was restricted by phosphate. Furthermore, different functional groups responded differently to Cu(Ⅱ) under different phosphate concentrations. The binding sequence of different functional groups under high concentration of phosphate (phenolic hydroxyl group＞amide (Ⅰ) ＞carbohydrates) was completely opposite to that with no phosphate. These results demonstrated that phosphate could restrict the binding affinity of heavy metals with different fluorescent substances or organic ligands of DOM, suggesting that the comigration of DOM-bound heavy metals in lakes is hindered by phosphate and the risk of heavy metal poisoning in aquatic organisms is therefore diminished.

In-situ observations of internal dissolved heavy metal release in relation to sediment suspension in lake Taihu, China

Despite laboratory experiments that have been performed to study internal heavy metal release, our understanding of how heavy metals release in shallow eutrophic lakes remains limited for lacking in-situ evidence. This study used automatic environmental sensors and a water sampling system to conduct high-frequency in-situ observations (1-hr intervals) of water environmental variables and to collect water samples (3-hr intervals), with which to examine the release of internal heavy metals in Lake Taihu, China. Under conditions of disturbance by strong northerly winds, sediment resuspension in both the estuary area and the lake center caused particulate heavy metal resuspension. However, the patterns of concentrations of dissolved heavy metals in these two areas were complex. The concentrations of dissolved Se and Mo increased in both areas, indicating that release of internal dissolved Se and Mo is triggered by sediment resuspension. The concentrations of dissolved Ni, Zn, As, Mn, Cu, V, and Co tended to increase in the estuary area but decrease in the lake center. The different trends between these two areas were controlled by pH and cyanobacteria, which are related to eutrophication. During the strong northerly winds, the decrease in concentrations of dissolved heavy metals in the lake center was attributable primarily to absorption by the increased suspended solids, and to growth-related assimilation or surface adsorption by the increased cyanobacteria. The findings of this study suggest that, short-term changes of environmental conditions are very important in relation to reliable monitoring and risk assessment of heavy metals in shallow eutrophic lakes.

Historical record of metals in Lake Küçükçekmece and Lake Terkos (Istanbul, Turkey) based on anthropogenic impacts and ecological risk assessment

The objective of this study was to determine the vertical distribution of metals and organic carbon in lakes Küçükçekmece and Terkos, which are located in different areas near Istanbul and are affected by different environmental factors. The aim was also to specify the metal input, its sources, and the ecological risk over the last 700 years. For analysis, core sediment samples were taken from the bottom of each lake, sliced into 2-cm sections, and analyzed for multiple elements, organic carbon, carbonate, and chlorophyll degradation products. It was determined that Lake Küçükçekmece is threatened by domestic and industrial pollution. To solve this problem, a treatment plant was commissioned in 2012 for the treatment of urban and industrial wastes. In addition, natural gas has been the preferred fuel for the last two decades in Istanbul and this has changed the pollutant profile. On the other hand, Lake Terkos faces possible risks of Mn, P, and As inputs because of fertilizer use in nearby agricultural fields.

Enrichment and geoaccumulation of metals in the superficial sediments of Lake Chivero, Zimbabwe

AbstractSediments act as a sink, being an integrator and an amplifier for metals in rivers, lakes and reservoirs. Thus, sediment quality has been recognized as an important indicator of aquatic pollution. The concentrations of aluminium (Al), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn) and sodium (Na) were studied in the surface sediments of Lake Chivero, Zimbabwe, to determine metal accumulation, distribution, pollution status and to distinguish natural background metal levels from human pollution sources. Sediment samples were collected from 17 locations during a two‐year (2014–2015) monitoring period during the hot–dry, hot–wet and cool–dry seasons. The overall mean metal concentrations exhibited the following decreasing order: Fe &gt; Al&gt;Mn &gt; Ca&gt;K &gt; Mg&gt;Na. The Mn levels for all sites and seasons were above the severe effect level (SEL). The highest metal and enrichment factor (EF) values were observed for the hot–wet season, indicating the period when the reservoir received the highest metal pollution from its catchment. The Geochemical index (Igeo) values for Mn for all seasons indicated moderately to strong contamination in sediments. The pollution load index (PLI) for all seasons indicated low pollution levels. Sediment contamination was attributed to natural sources for Al, Na and K and anthropogenic sources for Fe, Ca, Mg and Mn. The levels of studied metals in the Lake Chivero sediments are comparable to other eutrophic lentic systems. The results of the present study provide baseline information necessary for developing future metal pollution control strategies for Lake Chivero and its catchment.