Sources Of Trace Metals Research Articles

Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA

Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by various source inputs to the lake and complex biogeochemistry. Here, we leverage Hg and Pb stable isotopes to track relative changes in metal source contributions to Great Salt Lake over time. Mercury and Pb concentrations increase in sediments deposited after 1920 and peak between 1965 and 1995, following closure of several local smelters and the onset of increased emission controls. The nominal associations above are confirmed via Hg stable isotopes in pre-1920 background sediments, which reflect atmospheric inputs from regional and global origin, whereas Hg and Pb stable isotopes together indicate that elevated metal concentrations in mid-late 20th century sediments reflect increased mining/smelting inputs. The observed minimal rebound towards pre-1920 Pb isotope signatures in 21st century sediments indicates that mining/smelting inputs, though reduced, remain a primary source of Pb to Great Salt Lake. In contrast, the more pronounced rebound of Hg stable isotope signatures to pre-1920 values indicate a greater contribution of atmospheric inputs of regional/global origin to current Hg inputs, though Hg concentrations are ~10 times greater than pre-1920 background values due to global increases in atmospheric Hg concentrations or possibly slow recovery from local contamination. The importance of regional/global Hg sources to the system suggests that reductions in Hg bioaccumulation in the open water food webs of Great Salt Lake are more dependent on national and global reductions in Hg emissions and management strategies to limit methylmercury production within system. This work highlights the utility of using coupled Hg and Pb stable isotope values to assess trace metal pollution sources and pathways in aquatic systems.

Iron Isotopes reveal volcanogenic input during Oceanic Anoxic Event 2 (OAE 2 ∼ 94 Ma)

Anomalously high metal concentrations including iron enrichments are recorded in marine carbonates deposited during Ocean Anoxic Event 2 (OAE 2). These metal enrichments have been attributed to massive submarine eruptions during the formation of one or more large igneous provinces, the proposed trigger for OAE 2 (hydrothermal hypothesis), or to the release of metals from the reoxidation of formerly anoxic marine sediment during a period of temporary cooling during OAE 2 (sediment release hypothesis). Here we use iron stable isotopes to help distinguish between the two hypotheses for a trace metal enriched interval during OAE 2 in the Iona-1 core in the Western Interior Seaway, Texas. Our results show a two-step negative excursion during OAE 2 that is coincident with osmium isotope volcanic proxies measured in the same core, with peak negative values centered on a trace metal-enriched interval. After corrections for detrital and locally supplied iron to the study setting, the δ56Fe value of the remotely supplied iron is –0.28 ± 0.05 ‰, falling in the range of iron δ56Fe values observed in modern hydrothermal plumes (–0.1 to –0.5 ‰), thus supporting the hydrothermal hypothesis as the source of iron and other associated trace metals enriched in the study core during OAE 2. By contrast, the sediment release hypothesis predicts much lower δ56Fe values, between –1.0 ‰ to –3.3 ‰ predicted for benthic supplies of iron from anoxic marine sediment overlying re-oxygenated bottom waters. This study shows that combining iron with other proxies for environmental change, particularly submarine volcanism, can distinguish hydrothermally supplied iron from dust, rivers, and shelf sediment supplies of iron despite iron’s reputation for complicated cycling.

Source and health risks of trace metals in Clarias batrachus and Chrysichthys nigrodigitatus from surface waters in Bayelsa State, Nigeria: a probabilistic model

IntroductionHuman activities have inadvertently led to the release of harmful substances, including trace metals, into aquatic environments, with consequential impacts on aquatic organisms and potential health risks for consumers. This research assessed the presence, origins, and health implications of trace elements within the muscles of Clarias batrachus and Chrysichthys nigrodigitatus from the Bomadi and Gbotebo rivers and their surroundings in Bayelsa State, Nigeria.MethodsThirty samples from each fish species were collected and analyzed to conduct the study. Through the use of an atomic absorption spectrophotometer, the researchers determined the concentrations of trace metals, including iron, copper, zinc, lead, nickel, cadmium, and cobalt, in the fish tissues.Results and discussionThe concentrations of the metals within the two fish species varied, with notable differences in zinc and cadmium levels. Utilizing statistical analyses like Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (CA), it was established that the trace metals originated from diverse sources. The study then evaluated health risks associated with these trace elements, considering both non-carcinogenic and carcinogenic hazards for different age groups. The results indicated that children’s total target hazard quotient fell below 1 for both fish species, implying a limited tendency toward non-carcinogenic risks through lifelong fish consumption. However, in some adult fish samples, the quotient exceeded 1, indicating a higher potential for non-carcinogenic risks. Regarding carcinogenic hazards, the mean risks were generally lower than the accepted threshold, except for lead in both fish species among adults and children. Stricter values highlighted that only lead concentrations in fish from both categories were deemed acceptable. Consequently, this study highlights the importance of raising awareness among consumers who buy fish from the studied region. Moreover, consistent monitoring of potentially harmful trace elements in water, sediments, and fish is recommended to safeguard consumer health and well-being.

Sources and transport pathways of trace metals to the outer continental shelf off South Carolina and Georgia, USA revealed from the otoliths of moray eels

Trace metal concentrations in otoliths of spotted moray eels (Gymnothorax moringa), non-migratory residents of hard bottom reefs at depths of ∼30–70m along the outer shelf adjacent to South Carolina and Georgia, were analyzed to determine if results provide insights into trace metal sources and transport processes in this dynamic region of the shelf. Li and Mg appear to reflect exposure to local sea water circulated through adjacent porous rock outcrops where the eels reside. Concentrations of Mn, V, Cu, and Zn in otoliths appear to be associated with deep water upwelled along the shelf break. Based on 30 years of water temperature data from fishery surveys, Scamp Ridge, located at 32.30 N at a depth of ∼50m, has significantly lower summertime bottom temperature than elsewhere along the shelf edge, indicating locally enhanced upwelling at that location. The highest levels of Cu and Zn and the lowest of Mn and V were also found in otoliths of eels collected in the vicinity of Scamp Ridge. These results indicate that otolith chemistry in eels can reveal fine-scale structure of water mass inputs to the outer shelf of the southeastern US coast.

Trace elements accumulation in vegetables and soils of waste dumping sites in southwestern Bangladesh and implication on human health

The untreated municipal solid wastes (MSWs) dumping and improper management causes major concerns of environmental degradation and human health risks. In this study, we collected soil and vegetable from the MSWs dumpsites of Khulna City Corporation (KCC) in southwestern Bangladesh. Trace metals (Pb, Cd, Co, Cr, Cu, Ni, Zn, Fe, Mn) were measured to explore the health risk of cultivated vegetables from dumpsites. Soil contamination was evaluated by geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF), and pollution load index (PLI), while health risk was evaluated by transfer factor (TF), estimated daily intake (EDI), target hazard quotient (THQ). Results exhibited that the average trace metals in soil and vegetables followed in the order of Fe > Pb > Mn > Zn > Cu > Cr > Ni > Cd > Co. The Igeo, EF, CF, and PLI values revealed that the soil contamination was dominated by Pd, Cd, Mn, and Zn. The EDI of metals in vegetables were exceed the maximum daily intake only for Fe, Pb, and Cr. The total THQ was > 1, implying potential health hazards for the local people due to the long-term consumption of the cultivated vegetables. The multivariate analysis reveled that the sources of trace metals in the soils and vegetables of dumpsites were natural and anthropogenic. Overall, the findings suggest that growing vegetables in dumpsite is unsafe for long-term consumption by local inhabitants. Immediate action should be taken to protect the environment and human health from trace metal hazards.

Source apportionment of major ions and trace metals in the lacustrine systems of Schirmacher Hills, East Antarctica

The fabric of the Antarctic lacustrine system has a crucial role in assimilating the anthropogenic inputs and mitigating their long time impacts on climate change. Here, we present the changes in the concentrations of major ions and trace metals in the surface water of the lacustrine system to understand the extent of anthropogenic impacts from the adjacent Schirmacher Hills, East Antarctica. The results show that the land-locked lakes (closed-basin lakes surrounded by topographical barriers such as mountains or bedrock formations) in the region have a moderate enrichment in elemental concentrations compared to the pro-glacial lakes (marginal freshwater bodies that form at the terminus of a glacier or ice sheet). The water quality index (WQI: 7.58–12.63) and pollution evaluation index (PEI: 1.36–2.35) remained normal, indicating that the water in these lake are of good quality. However, a significant correlation between lithogenic elements (Al, Fe) and potentially toxic elements (Cd, Cr, and Ba), suggests an increase in the anthropogenic impacts. Based on the principal component analysis (PCA), the source of trace metals to the lacustrine systems appears to be the surrounding environment, followed by aerosol dust particles. Hierarchical cluster analysis (HCA) revealed that regional topography significantly impacts the supply of major ions/trace metals to these lakes. The present study provides baseline data and can be used to estimate and forecast future local and/or global anthropogenic contaminations in the lacustrine system of Schirmacher Hills, East Antarctica. Moreover, the presence of research stations (Maitri and Novolazarevskaya), tourist activities, and the potential for anthropogenic stressors necessitate continued monitoring and impact assessment programs within the Schirmacher Hills lacustrine systems. These programs are crucial for safeguarding this pristine ecosystem from future environmental disturbances under a changing Antarctic climate, as mandated by the Antarctic Treaty System and the Indian Antarctic Act.

Distributions of cadmium, nickel, zinc, copper, and iron in the western South Pacific Ocean: Local sources of the nutrient-type trace metals

This study presents comprehensive sectional distributions of five nutrient-type trace metals (Cd, Ni, Zn, Cu, and Fe) within the total dissolvable (td), dissolved (d), and labile particulate (lp) fractions along the GEOTRACES transect GP19 (∼170°W). Among these trace metals, only dCd exhibits a strong correlation with phosphate, albeit with a notable deviation at around ∼100 m depth for stations situated between 50°S and 0°S. This divergence indicates that the distribution of dCd is primarily influenced by ocean circulation and biogeochemical cycling in the western South Pacific Ocean. Conversely, dNi, dZn, and dCu concentrations increase independently of phosphate in waters exceeding 1500 m depth. These variations can partly be attributed to reversible scavenging, benthic release from sediments in the Fiji Basins and the Southwest Pacific Basin, and/or water mass mixing. While a moderate correlation exists between dFe and PO4 throughout the water column, the slope of the regression line is less than half of the Fe/P ratio observed in phytoplankton, suggesting substantial scavenging of dFe. Furthermore, the distribution of dFe is influenced by local sources such as intense weathering on tropical-subtropical lands and hydrothermal activities.

Geochemical and depositional environment of an Upper Cretaceous greensand giant (Münsterland Cretaceous Basin, Germany)

Based on integrated geochemical, mineralogical and stratigraphic-sedimentological analyses of core section KB 4507/1001 Essen-Bedingrade from the Münsterland Cretaceous Basin (northern Germany), the geochemical and depositional environment of a Late Cretaceous greensand giant has been elucidated. The >100-m-thick Cretaceous succession comprises the Essen Greensand (Cenomanian), Büren (lower Turonian), Duisburg (middle Turonian to lower Coniacian) and Emscher formations (middle to upper Coniacian), essentially consisting of alternating greensand and marl lithofacies. X-ray diffraction analyses showed that the abundant green grains undoubtedly constitute glauconitic minerals with high-order, 1M-type layer stacking. The depositional environment can be characterized as a shallow-marine setting in which nearshore greensands interfingered with mid-shelf marls. Inorganic geochemical analyses normalized to Al and compared to average shale (AS) show that most element/Al (E/Al) ratios are higher than AS values, including the chemical index of alteration (CIX). This suggest that an intensely chemically weathered wet hinterland provided for a constant supply of essential elements required for nearshore glaucony authigenesis under variably reducing or oxidizing conditions and slightly increased palaeoproductivity. The leaching of paleosols and swamp-like coastal wetlands during transgressive phases related to eustatic early Late Cretaceous sea-level changes was an important source for trace metals and nutrients while the considerable influx of terrestrial organic matter suggests a significant input of K related to plant decay. In a nutshell, our new integrated data from the Münsterland Cretaceous Basin provide important novel insights into the formative processes of authigenic glauconitic minerals during warm-humid climate phases of Earth history.

Iron dissolution from Patagonian dust in the Southern Ocean: under present and future conditions

Although the input of desert dust as a key source of trace metals in the Southern Ocean (SO) has been previously studied, the dissolution process of metals in surface waters, particularly iron (Fe), remain poorly understood. Given the crucial role of Fe in primary production and the biological carbon pump in the SO, we focused on experimental estimations of Fe dissolution from Patagonian dust, the primary natural dust source in the SO. Our study considered both current and projected future conditions, encompassing sea-surface warming, acidification, increased photosynthetically active radiation, and doubled dust inputs. Through controlled laboratory experiments using filtered SO seawater, conducted over 7 days, we assessed changes in particulate Fe (pFe) concentrations, Fe redox speciation (Fe(II)/Fe(III)), and in the mineralogy of Fe-bearing dust in abiotic condition. The predominant minerals in the dust included quartz and aluminosilicates, with silicon (Si), aluminum (Al), and Fe as the major elements. No significant alterations in the mineralogy and the elemental composition of the dust were recorded during the dissolution experiments, neither under present nor under projected future conditions. The particulate Fe(II)/Fe(III) ratio remained consistently at 0.25 during the experiments, unaffected by changed conditions. Consequently, changes in environmental conditions in the SO would therefore not significantly alter the mineralogy and redox speciation of pFe in the Patagonian dust. On the contrary, pFe exhibited a dissolution rate of 3.8% and 1.6% per day under present and future conditions, respectively. The environmental changes anticipated for 2100 in the SO will likely to result in a decrease in the dissolution rate of pFe. Thus, even though a doubling of dust input by 2100 is anticipated, it will unlikely provide significantly more dissolved Fe (dFe) in seawater in the SO. Consequently, the future intensification of Patagonian dust inputs may not alleviate the Fe limitation in the SO.

Rivers and tidal flats as sources of dissolved organic matter and trace metals in the German Bight (North Sea)

The German Bight in the southern North Sea receives nutrients, dissolved organic matter (DOM), and trace metals from rivers, porewater reflux, and porewater outwelling. We studied the marine, riverine, and porewater sources analyzing molecular transformations of solid-phase extracted (SPE) DOM in the German Bight. We applied a combination of ultrahigh-resolution mass spectrometry (FT-ICR-MS) with quantitative data of dissolved organic sulfur (DOS), dissolved black carbon (DBC), dissolved trace metals (Ba, Co, Gd, Mo, Mn, W), and nutrients (nitrite, nitrate, phosphate, silicate). While aromatic DOM and DBC mainly originated from the rivers, nitrogen-containing, more saturated DOM was enriched offshore suggesting greater contributions of marine (algal) sources. Except for dissolved Mo, rivers were the primary source of trace metals and nutrients. However, tidal flats contributed to dissolved nutrient (e.g., dissolved phosphate), trace metal and DOS inventories of the southern North Sea. The input of DOS from intertidal flats was identified by the molecular index derived from sulfidic porewaters (ISuP), non-conservative behavior of elemental sulfur-to-carbon ratio and sulfur content of molecular formulae (from FT-ICR-MS). Dissolved Mn and Si were removed in the German Bight, likely due to precipitation as Mn(hydr)oxides and biological uptake, respectively. Preliminary estimates suggest that DOS from porewater outwelling is approximately four times higher than DOS discharged by the three main rivers in the region. Our study therefore highlights the need to consider porewater discharge in addition to riverine sources to comprehensively assess elemental budgets within the complex interplay and transformations of DOM, nutrients, and trace metals in coastal ecosystems.

Elemental geochemical evidence for the river-derived sources of trace metals in surface sediments from Hangzhou Bay, East China Sea

Coastal estuaries are often heavily subject to riverine influences by the inputs of sediment from terrestrial sources. Hangzhou Bay (HZB) is threatened by the riverine derived trace metals from two large rivers of Qiantang River (QTR) and Yangtze River (YZR). However, previous studies mainly focused on the incidental transport from the largest river in China (YZR) and failed to simultaneously evaluate the contributions of these two rivers, especially the directly flowing river of QTR, by their trace elemental geochemical composition and distribution. Herein, a comprehensive study identified the river-derived sources of multiple trace metals in surface sediments which transported from both of the rivers. The sampling stations were separated into three regions of YZR, HZB, and QTR based on their spatial distributions of sediment grain size and components. The significant variations for most of the trace metals concentrations, except for Cd, Th, and U, were found among three regions (χ2 ≥ 8.22, p ≤ 0.016). The highest concentrations in HZB were mainly resulted from the grain size effect (68.82% of the total variance), while the highest concentrations of Sr, Cd, and Ba in YZR and Zr and Hf in QTR were attributed to the anthropogenic source (11.90%) and mineral composition (6.21%) of river basins. After normalized the diversity of multiple trace metals concentrations and the influence of grain size by ratios of Igeo and EFLi, three regions were effectively distinguished. It was indicated that As, Cd, and Sb were enriched in the sediments of rivers by anthropogenic source (EFLi > 1.5 and/or Igeo > 1). The results evidenced that, after removing the influence of grain size, elemental geochemical composition of the surface sediments confidently identified the river-derived anthropogenic sources of the enriched trace metals from two major rivers, and largely from YZR.

Magnetic particle detection as a surface soil source pollution in urban areas: Implication from magnetic and geochemical analysis along the major port city in China

The global concern for the level and sources of urban surface soil pollution has been increasing. In this study, we assessed the efficacy of the environmental magnetic method in identifying the sources of urban surface soil pollution in Ningbo, a prominent city in China. To achieve this, magnetic and geochemical measurements were performed on surface soil samples collected from 114 designated sites， supplemented by polarizing microscope observations. The mass-specific magnetic susceptibility values (χlf) exhibited a wide range, spanning from 25.45 to 1903.85 × 10−8m3kg−1, with an average of 295.45 × 10−8m3kg−1. Notably, lower magnetite concentrations were identified in the urban center, contrasting with higher values observed in the peripheral industrial areas. The average concentrations of Cu, Pb, Zn, and Ca were much higher than the background values. Anthropogenic sources such as traffic emissions, construction dust, and industrial processes emerged as the predominant contributors to surface soil pollution in Ningbo. Fuzzy cluster analysis was employed to discern possible relationships between magnetic properties and pollution sources. The results indicated three categories of pollution. Cluster 1 is related to natural (lithogenic and pedogenic) magnetic mineral sources, and the samples contained abundant quartz or feldspar. Notably, these samples are largely unpolluted. Cluster 2 is associated with a combination of natural and anthropogenic sources. Cluster 3 is dominated by spherical magnetic particles formed by high-temperature combustion. In Cluster 3 topsoil samples, ascertained to be contaminated through magnetic analysis, a significant Spearman correlation was observed between magnetic parameters and Cu, Cr, and Fe. In conclusion, magnetic properties provide a swift and effective method for characterizing surface soil pollution in Ningbo, enabling the tracing of sources for trace metals in the surface soil.

Quantification of Bioaccessible and Environmentally Relevant Trace Metals in Structure Ash from a Wildland-Urban Interface Fire.

Wildfires at the wildland-urban interface (WUI) are increasing in frequency and intensity, driven by climate change and anthropogenic ignitions. Few studies have characterized the variability in the metal content in ash generated from burned structures in order to determine the potential risk to human and environmental health. Using inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS), we analyzed leachable trace metal concentration in soils and ash from structures burned by the Marshall Fire, a WUI fire that destroyed over 1000 structures in Boulder County, Colorado. Acid digestion revealed that ash derived from structures contained 22 times more Cu and 3 times more Pb on average than surrounding soils on a mg/kg basis. Ash liberated 12 times more Ni (mg/kg) and twice as much Cr (mg/kg) as soils in a water leach. By comparing the amount of acid-extractable metals to that released by water and simulated epithelial lung fluid (SELF), we estimated their potential for environmental mobility and human bioaccessibility. The SELF leach showed that Cu and Ni were more bioaccessible (mg of leachable metal/mg of acid-extractable metal) in ash than in soils. These results suggest that structure ash is an important source of trace metals that can negatively impact the health of both humans and the environment.

Characterization of soil trace metal pollution, source identification, and health risk assessment in the middle reaches of the Guihe River Basin.

The natural environment, as well as human production and survival, is intrinsically dependent on soil. This study comprehensively assessed the pollution status, health risks, and sources of trace metals in the middle reaches of the River Gui Basin (MRGB) utilizing the geoaccumulation index, potential ecological risk index (PERI), and human health risk evaluation method. The findings of this study provide the following key insights: (1) only Cu and Pb levels in the MRGB soils did not exceed the background values established for soils in Weifang City (WFC). (2) The geoaccumulation status in most areas of the MRGB ranged from non-polluted to mildly polluted, with the overall ecological risk classification ranging from mild to moderate. (3) The cumulative non-carcinogenic risk for humans in the MRGB remained within acceptable limits, whereas the carcinogenic risk indices fell within tolerable levels. Oral ingestion emerged as the primary exposure pathway for both non-carcinogenic and carcinogenic health risks. (4) Cu, Zn, Ni, and Cr concentrations in MRGB soils primarily stemmed from natural sources associated with parent rocks, with Zn exhibiting additional influence from anthropogenic factors. In contrast, Pb, Cd, Hg, and As concentrations were predominantly driven by anthropogenic sources. Although the soils in the MRGB typically exhibited mild-to-moderate contamination levels, the contamination levels of Hg and Cd were notably more severe. As and Cr were significant health hazards. Most soil contamination sources are attributed to anthropogenic factors, warranting heightened attention from the relevant authorities.

Appraisal of trace metals toxicity and human health risk using a novel approach in wastewater of four gas fields, Bangladesh

The objective of this study is to assess the toxicity of trace metals (TMs) and associated environmental, ecological and health risks in the gas fields located in the Sylhet region of Bangladesh. Gas well-produced water, gas field discharge water, and drinking water surrounding the gas fields were collected for analysis. This study analyzed carcinogenic and noncarcinogenic TMs such as Cr, As, Co, Cd, Fe, Ni, Mn, Zn, and Pb, as well as physical parameters pH and EC in the collected samples using various instruments. The TMs were measured using Atomic Absorption Spectrometer (AAS), Flame AAS and physical parameters were evaluated using portable water multiparameter. The Fe and EC concentrations in produced and discharged water samples were incredibly high. The average concentrations of TMs in produced water samples during the summer and rainy seasons were found to be Fe > Mn > Zn > Ni > Co > Cu > Cr > Pb > As > Cd. The observed metal concentration in discharge water was higher during the summer than in the rainy season. Most samples met national and international standards for trace elements, while a few samples exceeded the threshold value.The Heavy Metal Evaluation Index (HMEI) results indicate that most produced water is highly polluted, while discharge and drinking water are moderate to lightly polluted. The Environmental Pollution Index (EPI) indicates environmental pollution for some produced water samples, while it indicates a moderate to low risk for discharge and drinking water samples. The source of trace metals (TMs) was determined using positive matrix factorization. However, all water samples have an ecological risk index of less than 150, indicating lower risk. Furthermore, the Heavy Metals Toxicity Load (HMTL) was below the allowable toxicity load for all water samples, indicating minimal contamination in the studied water. The non-cancer hazard score (HI) of the studied HMs is more significant for children and females than males. The cancer risk from Ni is a concern, while the cancer risk from Cd and Cr is also a matter of concern. In the end, policymakers can utilize this study's findings to monitor, and control produced water contamination.

Trace metals and pesticides in water-sediment and associated pollution load indicators of Netravathi-Gurupur estuary, India: Implications on coastal pollution

Various environmental indicators were used to evaluate the water and sediment quality of the Netravathi-Gurupur estuary, India, for trace metals and pesticide pollution. The descended order of studied metal concentrations (μg/L) in the water was Fe (592.71) > Mn (98.35) > Zn (54.69) > Cu (6.64) > Cd (3.24) > Pb (2.38) > Cr (0.82) and in sediment (mg/kg) was Fe (11,396.53) > Mn (100.61) > Cr (75.41) > Zn (20.04) > Cu (12.77) > Pb (3.46) > Cd (0.02). However, pesticide residues were not detected in this estuarine environment. The various metal indexes categorised the water as uncontaminated, whereas contamination factor, enrichment factor, geo-accumulation index, degree of contamination and pollution load index indicated low to moderate sediment contamination. Multivariate statistics showed that the dominance of natural sources of trace metals with little anthropogenic impact. Improvement in water/sediment quality during the study period might be due to COVID-19 imposed lockdown.

Spatial Variation, Ecological Risk, and Point Sources of Environmental Trace Metals in Lacustrine Ecosystems: An Assessment of Natural and Urban Inputs

ABSTRACT To gain insights into the spatial distribution, ecological risk and origins of heavy metals in surface sediments of lacustrine ecosystems in Cameroon, the content of 7 trace metals (Fe, Cr, Zn, Cu, Ni, Pb and Cd) in sediments from 60 sampling stations in 5 lacustrine environments of different formation contexts. The selected metals were investigated based on inductively coupled plasma mass spectrometry. The results revealed that the average concentrations of Cr, Cu and Cd were higher than the geochemical Threshold values. On the basis of the spatial variation, the studied metals vary quantitatively in the following order: Fe > Cr > Zn > Cu > Ni > Pb > Cd. The calculated enrichment factor (EF) and geo-accumulation index (Igeo) showed that, sediments from large cities and industrial sites had moderate enrichment (3 < EF ≤ 5) and were moderately to severely contaminated (2 < Igeo < 3) while those from low population and rural areas had minor enrichment (1 < EF ≤ 3) and were moderately contaminated (1 < Igeo < 2). With regards to cumulative pollution, the pollution load index (PLI) and the sediment pollution index (SPI) coupled with the potential ecological risk factor (Er) and the potential ecological risk index (RI), the sediments of the lakes are polluted (SPI and PLI > 1) to some extent but with a low ecological risk (Er < 40 and RI < 150). The results of Pearson correlation, principal component analysis (PCA), and cluster analysis (CA) identified three main sources: Ni would have a natural source; Pb from anthropogenic sources, and the other metals (Fe, Cr, Zn, Cu, and Cd) could have a mixed source (anthropogenic and natural). These findings serve as a scientific foundation for the advancement and use of these lake environments, which are the most attractive sites.

Source identification and risk assessment of trace metals in surface sediment of China Sea by combining APCA-MLR receptor model and lead isotope analysis

This study aimed to investigate the distribution, pollution, risk and sources of trace metals in sediments along China Sea. Clear spatial variations were found for Cr, Mn, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, and Pb, whereas As did not show spatial variation. East China Sea (ECS) contained the highest concentrations of Mn, Co, Ni, Cu, Zn, South China Sea (SCS) shallow sea contained the highest concentrations of Zn, Se, Mo, Ag, Cd, and Pb, whereas coral reefs contained the lowest concentrations of trace metals. Spatial variations could be explained by economic development characteristics along China Sea. As, Se and Cd exhibited low to moderate pollution in China Sea sediment, yet pollution for Cu, Zn, Ni, and Ag appeared in some regions. Sediment in ECS had moderate ecological risks and other regions at low ecological risks. The absolute principle component score-multiple linear regression (APCS-MLR) and Pb stable isotope indicated that 43–74% of trace metals (Ni, Cu, Zn, As, Se, Cd, and Pb) were derived from anthropogenic sources like traffic emission, agricultural activities, industrial source. No pollution and ecological risk were observed in coral reefs, yet 39–71% (Pb) was derived from anthropogenic activities such as motor vessels.

Spatial distribution and seasonal variation of trace hazardous elements contamination in the coastal environment

Groundwater is the second largest water source for daily consumption, only next to surface water resources. Groundwater has been extensively investigated for its pollution level in urban areas. The groundwater quality assessments in industrial areas associated with every urban landscape are still lacking. In order to examine the spatial distribution characteristics, pollution levels, and sources of trace metals in the densely populated Chennai coastal region of Tamilnadu, India, physicochemical parameters and trace element concentrations have been determined in groundwater. 55 groundwater samples from Tamil Nadu's coastal region were collected and analyzed for physicochemical parameters such as pH, (EC), (TDS), and (TH) during the pre-monsoon (June 2015) and post-monsoon (January 2016) seasons. We used trace elements and analyzed them in this study (Mg, Zn, Pb, Ni, Co, Cu, Cr, and Fe). Furthermore, anthropogenic input from industries and power plants exacerbates the pollution of Ni, Mg, Fe, and Mn. Due to evaporites and anthropogenic input, samples with excessive salinity, total hardness, and water quality are considered unsuitable for irrigation or drinking. The results demonstrated that seasonal, geogenic, and anthropogenic influences all have a significant impact on the heterogeneous chemistry of groundwater.

Cigarette filter fibres as a source and sink of trace metals in coastal waters

Cellulose acetate fibres from cigarette filters represent a form of microplastic that has received little attention in the environment. In this study, a ground composite of spent, smoked filter material (FM) has been used to investigate the role of cellulose acetate fibres as a source and a sink of trace metals (Cd, Co, Cu, Ni, Pb and Zn) in coastal waters. FM suspended in river water and seawater and mixtures thereof representative of an estuarine gradient resulted in the leaching of pre-existent metals derived from the combustion of tobacco, with mean percentages of release ranging from about 40 for Pb to nearly 90 for Cd, Co and Zn. Addition of 40 μg L−1 of each metal to FM suspensions incubated for 48 h yielded mean partition coefficients (KDs) ranging from <10 L kg−1 for Co to > 100 L kg−1 for Cu, Pb and Zn, with Cu and Ni displaying a net increase in KD with increasing salinity. Adsorption is interpreted in terms of hydrophobic interactions between metal-organic complexes and the cellulose acetate surface, and in support of this assertion KDs exhibited a significant, positive relationship with published metal-humic acid binding constants. The findings of this study improve our understanding of the role of cellulosic microfibres more generally in transporting trace metals in aquatic systems.