Degree Of Metal Contamination Research Articles

Determination of metals in water samples within the irrigation area in Telo District, Kaffa Zone, South Western Ethiopia

Water contamination due to the accumulation of metal is not only an environmental problem, but it is also a global issue. The river flows alongside the town in its downward direction, where runoff from the uplands and municipal trash discharge during floods may contribute to the contamination of the river. Despite the fact that this river is the area's primary source of water, the water near the effluent release point is extremely corrosive. The nearby settlements depend on this untreated river water for drinking, irrigation, and other domestic uses since they have no access to a municipal water supply. The aim of the present study was to evaluate the degree of metal contamination in the Obasho river water samples collected from irrigation water sites in the Gurguba region. Three samples were collected from each of four irrigation water sites, which were 1.5 km away from each other. A total of 12 water samples were collected by following the standard water sample collection protocol. 100 mL of the irrigation water sample was digested in aquaragia, and AAS was used to determine the concentration of metals in the water samples. The concentration ranges of some metals were: Ca (1.84387–2.810824 mg/L), and its maximum limit in FAO is 20.0 mg/L; Mg (3.176942–4.543031 mg/L), and its maximum limit in FAO is 5.0 mg/L; Cr (0.039227–0.047872 mg/L), and its WHO/FAO permissible level is 0.1 mg/L; Co (0.036703–0.057218 mg/L), and its permissibility level is 0.05 mg/L WHO/FAO, Cd (0.006198–0.02856 mg/L), whose maximum limit in FAO is 0.01 mg/L, and Pb (0.065138–0.091131 mg/L) WHO/FAO permissible level is 5.0 mg/L. The mean concentrations of metals (Ca, Mg, Co, Cd, Pb, and Cr) in all study sites were below the regulatory limits except for Co and Cd; no water contamination was caused by these metals at the study sites. However, the mean concentration levels of Co in all study sites were above regulatory limits. The mean concentration of Co at Konit Kochito and Cd at Geremew Mamo, Konit Kochito, and Gereno Gebito is also greater than regulatory limits. A pair-wise comparison of some metals in study sites was carried out, thus the mean concentration of the irrigation water sites sample was significantly different from some metal concentration (p < 0.05) at the 95% confidence level. Generally, there was no cumulative effect of water contamination caused by Ca, Mg, Co, Cd, Pb, and Cr in Gurguba Kebele study sites, and it may not appear to pose very serious environmental problems at this moment. Thus, determining the metal content in irrigation water samples is crucial for ensuring the safety and sustainability of agricultural practices. It raises awareness regarding the contents of heavy metal contamination and sets limits for acceptable metal concentrations. It has also vital role in maintaining soil health.

Morphological, chemical and growth patterns characterization in shells of Phorcus species along the northeastern coasts of Tunisia

This work is a characterization of the morphometry, the relative growth and the metal contamination degree of the shells of two species belonging to Phorcus genus along the northeastern rocky coasts of Tunisia. The gastropods were sampled from nine locations during the winter 2017. Our findings suggested a spatial morphometric variability probably linked to the extent of the continental shelf, the coasts’ geomorphology, the dynamics of water masses, the predation and the competition effects. Furthermore, the shell investigation allowed the study of the growth pattern and indicated that the development in shell size was faster than the increase in weight. Moreover, the use of Phorcus shells as bioindicators of long-term metal contamination seems to be of growing interest, due to their abundance, high longevity, easy sampling and ecobiological features, both in a scientific and ecosystem management perspective that aims to the establishment of conservation measures targeting marine coastal environments.

Health risk assessment and potential sources of metals in riparian soils of the Wujiang River, China.

In order to understand the pollution status of metals in the riparian soils along the Wujiang River, 26 sampling sites in the mainstream and tributary streams were selected for investigation. The geo-accumulation index (Igeo), Nemerow integrated pollution index, and potential ecological risk index were applied to evaluate the contamination status and ecological risks of metals. Results revealed that the average concentrations of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn were 12.20, 0.51, 84.01, 57.42, 922.57, 38.37, 38.06, and 127.82mg/kg, respectively. The metal contamination degree and ecological risks in the upper reaches were significantly higher than those in the middle and lower reaches of the Wujiang River. Cd was the dominant contamination metal. Significant non-carcinogenic and carcinogenic risks of metals were found in children based on the hazard index and carcinogenic risk. As was the main non-carcinogenic and carcinogenic pollutant metal in both adults and children. According to principal component analysis, hierarchical clustering analysis, and absolute principal component scores-multiple linear regression, anthropogenic sources (mining and agricultural activities) contributed most to Zn, Pb, Cr, Cd, Cu, and Ni, with contribution rates of 89.14, 82.32, 74.46, 72.12, 68.52, and 61.02%, respectively. Natural sources contributed most to Mn, with a contribution rate of 83.07%. Unidentified sources contributed most to As, with a contribution rate of 47.27%.

Trace elements in the muscle and liver tissues of Garra shamal from the freshwater ecosystem of Oman: an exposure risk assessment

Anthropogenic activities lead to environmental contamination with foreign substances such as heavy metals. This work was aimed to monitor trace elements (total arsenic (As), cadmium (Cd), chrome (Cr), cobalt (Co), copper (Cu), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni), and zinc (Zn)) contamination levels (dry weight base) in three natural freshwater reservoirs of Oman including Al Khawd and Al Amarat (Muscat Governorate) and Surur area (Ad Dakhiliyah Governorate as control area) using a native benthic inland fish (Garra shamal; Cyprinidae) for the first time. The muscle and liver of a hundred and twenty G. shamal were collected to assess the degree of metal contamination. Atomic absorption spectrometry was used as an analytical technique. From the spectrum of analyzed elements, we found Zn as a major element in monitored areas. The statistically significant (P < 0.05) highest concentrations of Zn liver (0.275 ± 0.065 µg/g) were in Al Amarat compared to the other areas. The concentrations of monitored elements in the fish muscle were lower than the liver samples. Furthermore, the fish length was significantly correlated with the accumulation of Hg and Co in both muscle and liver samples. In all analyzed fish from Oman inland water, the concentrations of elements were below the permissible limits; however, additional research is needed.

Contamination and Ecological Risk Evaluation of Metals in Sediments from a Wetland of International Importance (Ramsar Site)

Wetlands are highly productive and diverse ecosystems providing home to thousands of organisms. These ecosystems reduce water pollution, sequester carbon, support livelihoods, and increase food security. However, these ecological functions are being impeded due to increased levels of metals in the environment. Therefore, the primary objective of this study was to evaluate the degree of metal contamination in the surface sediment of a wetland, Tanguar Haor, for the first time. The result demonstrated that the mean concentrations of Fe, Cu, Zn, As, Pb and Hg varied from 13140.39 to 45675, 40.07 to 46.29, 47.60 to 57.15, 18.89 to 35.23, 1.24 to 2.64, and 0.35 to 0.42, respectively. The concentration of As was found to be higher than the average shale value. The concentration of Cu (44.19 μg/g) and Hg (0.38 μ/g) was very close to the shale value (45 μg/g and 0.40 μg/g, respectively), indicating a moderate level of contamination. The contamination level was further evaluated by multi-indices, e.g., the contamination factor (CF), the enrichment factor (EF), and the geo-accumulation index (Igeo). The average EF values for As (115.41), Cu (57.68), and Hg (55.47) were &gt;50, indicating a high degree of contamination (extremely severe enrichment). However, CF values showed varied levels of pollution; for example, the majority of the area was only somewhat contaminated with As, Cu, and Hg, but less contaminated with Fe, Zn, and Pb. According to Igeo, sampling sites were found to be unpolluted or less polluted by heavy metals. Based on potential ecological risk assessment (PERI), the degree of risk from the six heavy metals decreased in the following sequence: As &gt; Cu &gt; Zn &gt; Pb &gt; Cr &gt; Ni. PERI values indicated the study area has been exposed to moderate risk to As and low risk to other metals. This study provides an opportunity for frequent monitoring of heavy metals in this ecologically critical environment, and thus curbing heavy metal pollution.

Impact of anthropogenic pollution on the soil near the industrial area of Hrazdan town

Identifying the distribution of a number of heavy metals near the industrial area, taking into account the wind rose in the region during the period of operation of the Hrazdan Thermal Power Station and the Hrazdan Cement Plant was investigated in a radius of one km. In a series of experiments, was found a decreased concentration of arsenic and mercury in soil samples by an average of 27% with distance from the industrial area. In that direction, in the soil sample, there is an increase in the concentration of zinc and nickel by an average of 25.5%, as well as an increase in the concentration of copper by 19%. At the same time along the sampling line, the comparative series generally has the following sequence: As&lt;Ni&lt;Co&lt;Cu&lt;Zn&lt;Pb. In the quantitative assessment of soil, contamination was compared to geo-ecological coefficients: the danger level of soil contamination and the total pollution index. Their calculation was based on the values of heavy metals concentration according to Clark and their maximum allowable concentration. Our forthcoming studies will focus on identifying the dose-effect-rose-wind relationship in arable soils with varying degrees of metal contamination as a result of long-term anthropogenic pollution.

Geoenvironment and weathering of silicate minerals in sediments of the Brahmaputra river, India: Implications for heavy metal pollution assessment

We carried out detailed compositional studies on fifteen sediment samples from the Brahmaputra River that were collected in the pre-monsoon period, to obtain the inherent contamination factor. The present study demonstrates that the degrees of metal contamination in the sediments of the Brahmaputra river. Typical metals Fe, Al, Ti, Pb, Zn, Cu, Ni, Co, Mn and Cr, have been evaluated using several parameters like, enrichment factor (EF), contamination factor (CF), geo-accumulation index (Igeo) and pollution load index (PLI). The relative distributions of the contamination are found to be: Al > Fe > Ca > Mg > Ti > Mn > Cr > Cu > Zn > Ni > Pb > Co. The suspended sediments have been found to be moderately contaminated by the elements Cu, Pb, Cr, Mn and Ni. The nature of weathering is estimated using plagioclase index of alteration (PIA), chemical index of alteration (CIA), chemical index of weathering (CIW) and index of compositional variation (ICV). The studied suspended sediment samples indicate an intermediate silicate weathering of adjoins area.

Metal enrichment and toxicity assessment through total and speciation of metals in lower and middle regions of tropical (Mandovi) Estuary, western coast of India.

The study aimed to understand the metal enrichment and toxicity in lower and middle regions of a tropical Mandovi Estuary, revealed metals dilution by coarser intertidal mudflat sediments in the lower estuary (downstream of the fishing jetty-core S). A relatively calm depositional environment prevailed at the middle estuary (core M) and also at the upstream of the jetty of the lower estuary (core L) facilitating deposition and enrichment of Mn and Zn in cores M and Mn, Cu and Co in core L. The distribution of trace metals in sediments was regulated by grain size, total organic carbon and Fe-Mn oxides. The potential contamination index indicated a moderate degree of metal contamination in sediments while the anthropogenic factor showed the signatures of human-induced activities in the enrichment of metals. The sequential extraction of metals showed bioavailability of Mn, Cu, Zn and Co. Fe-Mn oxide and organic/sulphide were key phases for the retention of bioavailable metals. The elevated level of these metals suggested possible toxicity to benthic biota, particularly from Mn (cores L and M) and Co (core L) according to the screening quick reference table.

CONTRIBUTION TO THE STUDY OF THE PHYSICO-CHEMICAL QUALITY OF THE SURFACE WATER OF THE RIVER SEYBOUSE

Like all parts of the North- east Algeria, the study area has considerable surface water wealth, to which attention must be reserved. River Seybouse, which is fed by a network of rivers, is one of the most important rivers of this region; it drains the Guelma basin towards West-East clearly on nearly 45 km with a total contribution estimated at 408 Hm3/ year to Boudraoua station (Bouchegouf). In parallel with the rapid population growth, record the development of agricultural and industrial sectors that knows the study area in recent decades, River Seybouse, became the seat of important illegal dumping and polluting discharges. For this purpose, samples of water samples were conducted at nine stations during wet periods and dry periods. A multidisciplinary analysis concerned in particular, the physicochemical parameters (T°, pH, CE, O&lt;sub&lt;2&lt;/sub&lt;, Cl&lt;sup&lt;-&lt;/sup&lt;, PO&lt;sub&lt;4&lt;/sub&lt;, NO&lt;sub&lt;2&lt;/sub&lt; and NO&lt;sub&lt;3&lt;/sub&lt;), the evaluation of contamination by trace elements (Fe, Mn, Cu, Zn). The analysis results show that the waters of this river are characterized by high natural mineralization and concentrations substantially higher than the standards recommended by OMS and Algerian standards of the various parameters reflecting generally the waters of this course of water are of good quality. The concentrations of metallic elements are not alarming, and the degree of metal contamination differs from one site to another depending on the distance away from the source of pollution.

Physicochemical and Heavy Metal Assessment of the Udu River, Delta State, Nigeria

The Udu River is a major source of commerce and provides water for agricultural and domestic use to the Udu people, hence we studied the physicochemical parameters (pH, electrical conductivity, TSS, TDS, turbidity, Salinity, DO, COD, BOD, chlorides, sodium, potassium, total hardness, alkalinity, nitrates, ammonium, sulphates) as well as the evaluation of the degree of metal contamination (iron, zinc, cadmium, nickel, copper and lead) present in the samples. The analyses carried out revealed water samples were acidic, pH below 7, temperature ranged from 29.5 oC - 32.7 oC which was above WHO permissible limit 25oC, low levels of Dissolve oxygen DO (DO: max = 6.5 mg/L below WHO limit of 7.5 mg/L) and BOD ranges did not exceed the suggested 4.5mg/L (WHO max. limit). Concerning the heavy metals, the examined results showed lead, nickel, copper and zinc all below the WHO max limit. A significant increase in the concentration of Iron was noticed in Ovwian sampling site, also there was also build of cadmium above WHO limit 0.003mg/L at Igbogidi.

Accumulation of Potentially Toxic Metals in Egyptian Alluvial Soils, Berseem Clover (Trifolium alexandrinum L.), and Groundwater after Long-Term Wastewater Irrigation

The reduced availability of water resources in Egypt has imposed the need to intensify the use of wastewater for crop irrigation in the alluvial soils. Relevant effects can derive from contents of potentially toxic metals (PTMs) in supply resources soils, crops, and groundwater in these areas. For this reason the PTM content has to be monitored to evaluate and minimize health hazards. Therefore, in this context, two areas of the SE Nile Delta subjected to 25 year of wastewater irrigation, using agricultural drainage water (ADW) and mixed wastewater (MWW) were chosen and compared with a nearby site irrigated with Nile freshwater (NFW). At each of the three sites, ten samples of irrigation water, topsoil, berseem clover (Trifolium alexandrinum L.) plants, and seven groundwater samples were collected and analyzed for Cr, Co, Cu, Pb, Ni, and Zn. Results indicate that the total contents of Co, Cu, Ni, and Zn in soils collected from the three sampling sites and Pb in the MWW-irrigated soils were higher than their average natural contents in the earth’s crust, indicating potential risks. The DTPA-extractable contents of Cu in the three sites, in addition to Pb and Zn in the MWW-irrigated soils, exceeded the safe limits. The MWW-irrigated soils showed a considerable degree of metal contamination, while the NFW- and ADW-irrigated soils showed moderate and low levels of contamination, respectively. The contents of the six PTMs in the three sites showed low individual ecological risks, except for Pb in the MWW-irrigated soils that showed a moderate risk; however, the overall ecological risk remained low in all samples. The values of Co, Cu, and Ni in berseem shoot in addition to Pb from the MWW-irrigated soils were over the maximum permissible levels for animal feeding. Values of root-to-shoot translocation factor were lower than 1.0 for Cr, Co and Ni but higher than 1.0 for Cu, Pb, and Zn. Berssem plant is a good candidate for phytofiltration of Cr, Co and Ni, while for extracting Cu, Pb and Zn from polluted soils. The groundwater samples collected from the three sampling sites showed lower metal concentrations than the safe limits for drinking standards. Further remediation studies should be taken into account to alleviate potential environmental and health-related risks when using supply resources different from freshwater.

Thresholds of Metal and Metalloid Toxicity In Field-Collected Anthropogenically Contaminated Soils: A Review

Ecotoxicological studies of soil metal toxicity conventionally rely on the use of uncontaminated soils gradually enriched with metals in the form of soluble salts. Although this method is very useful in many ways, it is continually complicated by the difficulty of extrapolating laboratory results to actual field-collected soils exposed to decades of contamination. Although many studies emphasize the importance of using field-contaminated soils for toxicity bioassays, the number of studies actually conducted based on this premise is relatively small. This review provides an in-depth recompilation of data on metal toxicity thresholds in field-contaminated soils. We have summarized the EC10, EC25, and EC50 values for metals, i.e., values of metal concentrations that reduce the response of specific organisms by 10%, 25%, and 50% of the value in uncontaminated soils. In our summary, most studies show that total metal content can predict organismal responses as well as bioavailable fractions. These results are consistent with the intensity/capacity/quantity concept proposed for plant nutrient uptake. In addition, microorganisms are thought to be more sensitive to metals than plants and invertebrates. However, our analysis shows that there is no statistically significant difference between the sensitivity of microorganisms and other organisms (plants and invertebrates) to any metal or metal pool. We expect that this information will be useful for environmental assessment and soil quality decisions. Finally, we encourage future studies to analyze dose-effect relationships in native field-collected soils with varying degrees of metal contamination from long-term anthropogenic pollution.

Assessment of the Accumulation Ability of Festuca rubra L. and Alyssum saxatile L. Tested on Soils Contaminated with Zn, Cd, Ni, Pb, Cr, and Cu

The contamination of soils with metals applies, in particular, to areas related to industry, the mining of raw materials and ores, transport, and agriculture. Unlike organic materials, metals cannot degrade over time and need to be reduced, removed, or immobilized in soil. One of the remediation methods for soils contaminated with metals is phytoextraction, which uses plants’ ability to accumulate metals in their own tissues. Metals enter the plant organism through the roots and are transported to the aboveground parts, where they are accumulated. In this study, we evaluated the phytoaccumulative abilities of two plant species tested on soils from industrial areas contaminated with metals to different extents (Zn, Cd, Ni, Pb, Cr, and Cu). The research was conducted for three years under the conditions of a pot experiment. In order to obtain four soils with varying degrees of metal contamination, two soils from industrial areas, G1 (contaminated) and G2 (uncontaminated), were mixed in the following ratios: 1:1, 1:3, 1:7, and 1:9. In the phytoremediation process, Festuca rubra L. and Alyssum saxatile L. were tested. After analyzing the results of the bioconcentration factor (BCF) for the tested plants, it was noted that both of the tested plants accumulated Cd and Zn more easily, followed by Cu, Ni, and Cr, and then Pb to a lesser extent. The values of factors for Cd and Zn were correlated with the high mobility of these elements compared to other metals and their relatively easy uptake by plants. Alyssum saxatile L. has an ability to accumulate Cd compared to Festuca rubra L., which is confirmed by the BCF (0.764) and transfer factor (TF) (3.5) (for 1:7 combination) values. The calculated results for the BCFs for Alyssum saxatile L. are less than one for all tested metals, which allows us to state that Alyssum saxatile L. is not an accumulator.

Heavy Metal Contamination and Ecological Risk Assessment of Overlying Water and Sediments of Nkozoa Lake (Southern Cameroon)

Examination of heavy metals (Cr, Cu, Zn, Pb, Hg, Cd and Ni) in overlying water and sediments was conducted in Lake Nkozoa, in a peripheral area of Yaoundé characterized by a high population density and rapid economic development in Cameroon. Sediment samples were collected at the entrance and near the center of the lake, using a raft and polyvinyl chloride (PVC) pipes. They were subjected to water quality parameters, heavy metals comparisons and calculations of pollution indices and ecological risks followed by statistical analysis in order to identify and estimate the sources of metal contamination in overlying water and sediments of the Nkozoa Lake. The physico-chemical parameters of water show that the pH (5 &lt; pH &lt; 6), total dissolved solids (TDS~130 g/L) and conductivity (EC~194.8 µs/cm) are below the recommendations of the WHO. The average heavy metal concentrations in sediments, except Cd, are lower than the upper continental crust (UCC) and several environmental contamination monitoring parameters, such as threshold effect level (TEL), probable effect level (PEL), and severe effect level (SEL). The sediment samples show a low heavy metal contamination degree (class 0) and low potential ecological risk (PER) level, except for Cd and Hg which have high contamination degree (class 1 to 6) and moderate PER. Matrix correlation shows that some parameters like pH, EC, Cr and TDS, Cu, Hg in water have perfect positive correlations (r = 1.00) suggesting common sources of contamination. Cluster analyses coupled with matrix data for sediments revealed that Cd is the most contaminant elements derived from anthropogenic sources.

Non-carcinogenic and Carcinogenic Risk Assessment of Heavy Metals Exposure to Indoor Dust in Kathmandu, Nepal

The present study was carried out to assess the contamination of heavy metals in indoor household dust of Kathmandu, Nepal, and its adverse effect on the indoor environment and human health. The concentrations of four heavy metals (Cd, Cr, Ni, and Pb) in a total of ninety-three (N = 93) indoor dust samples collected from four different types of land use zones viz., commercial, heavy traffic, residential, and control (undisturbed) of Kathmandu were determined by the flame atomic absorption spectrophotometer (FAAS). The mean concentrations of Cd, Cr, Ni, and Pb in indoor dust samples over the study zones were 0.89, 158.1, 113.3, and 65.3 mg kg−1, respectively. The land use zones showed the various degree of metal contamination in indoor dust ranging from moderate to considerable level. PLI showed a high pollution load in the monitored locations, indicating an alarming condition and the urgent need for immediate remedial actions. Hazard quotient (HQ) values indicated ingestion as the major pathway of indoor dust heavy metal exposure to children while the inhalation pathway remained dominant in adults. Hazard index (HI) values showed no probable non-carcinogenic risk of the heavy metals present in the indoor dust of Kathmandu. For carcinogenic health risk, TLCR values were found within the acceptable safe limit indicating no cancer risk for both the receptor groups.

Pollution indices and health risk assessment of heavy metals in floodplain of urban catchment of Asa drainage systems, southwestern Nigeria

Urbanization and industrialization have significantly caused deterioration of surface waters. Since there is close association between river quality and its associated floodplain, the later could therefore provide a quality index of the former. This study examines heavy metal concentrations in floodplain sediment of urban catchment of Asa River and assessed associated risks. Samples were collected at 10 points but at interval of 5cm in vertical profile to a depth of 15cm. Atomic Absorption Spectrophotometer (AAS) analyses were done for Pb, Ni, Zn, Fe, Cu and Al. The following computational models were employed for risk analysis; Depth Ratio (DR), Contamination Factor (CF), Degree of Contamination (Cdeg), Geoaccumulation Index (Igeo), Pollution Load Index (PLI), Hazard Quotient (HQ), Hazard Index (HI) and Cancer Risk Index (CRI). Considerable degree of metal contamination was observed with various pollution levels from non-pollution with Ni, through moderate pollution with Pb, to a moderately strong pollution with Zn, Fe, Cu and Al. PLI revealed a baseline pollution level (PL ≈ 1) but contamination factor for each of Zn, Fe and Cu was considerable and may pose ecological threats and by extension, human health. Metal association reveals a positive correlation among all the metals evaluated (p < 0.05) which is suggestive of similar source. HQ via ingestion and dermal routes calculated were > 1 for both children and adult but< 1via inhalation. CRI for lead shows that children arepredisposed to cancer risks than adults. Hence, industrial activities in the urban catchment of Asa River must be monitored for environmental compliance.

Mercury, Lead, and Cadmium in the Muscles of Five Fish Species from the Mechraâ-Hammadi Dam in Morocco and Health Risks for Their Consumers.

This study aims to assess the degree of metal contamination (mercury (Hg), cadmium (Cd), and lead (Pb)) in the muscles of five species of fish Esox lucius, Sander lucioperca, Micropterus salmoides, Lepomis macrochirus, and Scardinius erythrophthalmus, from the Mechraâ-Hammadi Dam between July 2017 and May 2018, and to conduct a risk assessment for human consumers. Trace metals were determined by Graphite Furnace Atomic Absorption Spectrometry for the Pb and the Cd and by Cold Vapor Atomic Absorption Spectrometry for the Hg. The results gotten from the study of the muscles of the different fish species show that the higher mean amounts of Cd and Hg were determined in E. lucius, and the maximum mean levels of Pb were detected in S. erythrophthalmus. Results suggested that demersal fishes inhabiting near the sediments and piscivorous fishes with higher trophic level were likely to accumulate higher trace metal concentrations. The general order of bioaccumulation of the trace metals measured in the muscles of the fish species is as follows: Hg > Pb > Cd. Therefore, the bioaccumulation of Hg in fish studied is more important than that of Cd and Pb. Furthermore, these concentrations are higher in summer than in winter for all trace metals. All the values of the trace metals in the muscle tissues are below the maximum limits recommended by the European Community (EC) N° 1881/2006. However, estimation of noncarcinogenic health risks by the target hazard quotient indicated no obvious noncarcinogenic risks to humans that consume those fishes (THQ < 1). Results of THQ and maximum safe consumption indicated that Hg may cause more harm to human by fish consumption especially for E. lucius and S. lucioperca. Therefore, reduced intake of carnivorous fishes should be promoted as part of a healthier diet.

Accurate Determination and Comprehensive Evaluation of Heavy Metals in Different Soils from Jilin Province in Northeast China

To provide technical support and theoretical guarantee for the prevention and control of soil heavy metal pollution, the main types of topsoil and parent material in Jilin Province were systematically collected, accurately tested by atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry, and comprehensively evaluated through five indexes. By principal component analysis, it was initially judged that there were 2 or 3 major heavy metal sources in topsoil, which could be attributed to the parent material, soil-forming process, and/or anthropogenic factor. The pH of surface soil mainly depended on its parent material, and changed to a certain extent during its formation. The contents of heavy metals As, Hg, Cd, Cr, Cu, Ni, Pb, and Zn in surface soils were both significantly influenced by parent materials and soil-forming processes. Here the geo-accumulation index calculated by corresponding background value of parent material was more suitable for pollution assessment than the other four indexes, and the heavy metal contamination degree in each type of soil basically followed the order: Hg > Cd > Cu, Pb, Zn, As > Cr, Ni. Furthermore, the heavy metal contamination level in the types of soils was ranked as follows: cambisol, phaeozem > podzol, planosol > chernozem. The health risk assessment indicated that the soil in the study area had no significant carcinogenic or non-carcinogenic risks. Excluding the influence of parent material and soil-formation process, the comprehensive evaluation of soil heavy metal pollution will be more reasonable.

Quantifying Source Apportionment, Co-occurrence, and Ecotoxicological Risk of Metals from Upstream, Lower Midstream, and Downstream River Segments, Bangladesh.

The positive matrix factorization (PMF) receptor model was used for the first time to quantify the source contributions to heavy metal pollution of sediment on a national basin scale in the upstream, midstream, and downstream rivers (Teesta and Kortoya-Shitalakkah and Meghna-Rupsha and Pasur) of Bangladesh. The metal contamination status, co-occurrence, and ecotoxicological risk were also investigated. Sediment samples were collected from 30 sites at a depth range of 0 to 20 cm for analysis of 9 metals using inductively coupled plasma-mass spectrometry. The mean concentrations of metals varied for upstream, lower midstream, and downstream river segments. The results showed that chromium (Cr) exhibited a strong significant co-occurrence network with other metals (e.g., manganese [Mn], iron [Fe], and nickel [Ni]). Monte Carlo simulation results of the geo-accumulation index (Igeo; 63.3%) and risk indices (48.5%) showed that cadmium (Cd) was the main contributor to sediment pollution. However, the cumulative probabilities of sediments being polluted by metals were ranked as "moderate to heavily polluted" (Igeo 46.6%; risk index 16.7%). Toxicity unit results revealed that zinc (Zn) and Cd were the key toxic contributors to sediments. The PMF model predicted metal concentrations and identified 4 potential sources. The agricultural source (factor 1) mostly contributed to copper (Cu; 78.9%) and arsenic (As; 62.8%); Ni (96.9%) and Mn (83.5%) exhibited industrial point sources (factor 2), with 2 hot spots in northwestern and southwestern regions. Cadmium (93.5%) had anthropogenic point sources (factor 3), and Fe (64.3%) and Cr (53.5%) had a mixed source (factor 4). Spatially, similar patterns between PMF apportioning factors and predicted metal sources were identified, showing the efficiency of the model for river systems analysis. The degree of metal contamination in the river segments suggests an alarming condition for biotic components of the ecosystem. Environ Toxicol Chem 2020;39:2041-2054. © 2020 SETAC.

Assessment of metal contamination and their ecological risks in wetland sediments of the former Texcoco saline lake, Mexico

Texcoco saline lake in Mexico is an important habitat for over 300 species and recharges the Mexico City aquifer. Presently, it is on the verge of disappearance due to increasing anthropogenic pressure and comprises only a few wetland remnants. The impacts of human activities on these wetlands are unknown and uninvestigated. In this regard, this study investigates the degree of metal contamination in this ecosystem during the period of 2015–2018. Twenty-six sediment samples were collected from nine different wetlands of Texcoco Lake and examined for 17 metals (Al, Fe, Ca, Mg, Na, K, As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Hg) using atomic absorption spectroscopy. The degree of metal accumulation and its ecological risks were evaluated on the basis of several indicators (geoaccumulation index, enrichment factor, sediment quality guidelines, ecotoxicological values, and potential ecological risk index). Furthermore, co-occurrence via multivariate statistical techniques was employed using the measured metal concentrations to identify their possible sources. The Cd, Cu, Pb, Zn, and Hg sediment concentrations were higher in magnitude than the background North American shale composite values, suggesting their external origin in all studied sediments. According to the calculated enrichment factors and geoaccumulation index, the sediments were mostly contaminated with Cd and Hg. The sediment quality guidelines and ecotoxicological values together with the ecological risk index suggested probable adverse biological effects due to the presence of Cr, Cu, Ni, and Hg. Cadmium and Hg accounted for nearly 51 and 45% of the ecological threat in the sediments. Based on the knowledge about metal levels and co-occurrence in different matrices and the multivariate data analyses of the detected metal concentrations, we infer that the main sources of metals are as follows: (1) Solonchaks and Vertisol soil types (Ca, Mg, Na, and K); (2) urban-industrial effluents from surrounding municipalities and Mexico City (Cu, Pb, and Zn); and (3) industrial discharges of Xalostoc zone (Cd and Hg) near Texcoco. Our results emphasize the impacts of unregulated discharges from municipal, industrial, and metropolitan zones of Mexico City and construction activities for the elevated metal concentrations in the wetland sediments of Texcoco Lake.