Trace Metal Contamination Research Articles

Historical records of trace metals in two sediment cores of Jiaozhou Bay, north China

To investigate the long-term effects of urbanization and industrialization on coastal trace metal contamination, two sediment cores, Q21 (representing 1965–2018) and Q23 (representing 1986–2018), collected from the adjacent coasts of the east old town and west new area of Qingdao were analyzed. Although the concentrations of As, Cd, Co, Cr, Cu, Ni, Pb, Sc, and Zn were higher in Core Q21, the increasing trends in their concentrations and contamination levels were more obvious in Q23, especially since the 2000s. Moreover, the urbanization rates of the new area (1978–2017) were significantly positively correlated with the historical metal concentrations in Q23. Affected by the rapid socio-economic development in the new area, the combined excessive concentrations of the eight metals (excluding Sc) increased faster in Q23 (0.14–78.4 mg/kg) than Q21 (0.58–45.3 mg/kg). Overall, the sediment Core Q23 experienced higher trace metal contamination and ecological risks than Core Q21.

“Non-traditional” stable isotopes applied to the study of trace metal contaminants in anthropized marine environments

The advent of Multicollector ICP-MS inaugurated the analysis of new metal isotope systems, the so-called “non-traditional” isotopes. They are now available tools to study geochemical and ecotoxicological aspects of marine metal contamination and hence, to push the frontiers of our knowledge. However, such applications are still in their infancy, and an accessible state-of-the-art describing main applications, obstacles, gaps, and directions for further development was missing from the literature. This paper fills this gap and aims to encourage the marine scientific community to explore the contributions of this newly available information for the fields of chemical risk assessment, biomonitoring, and trophic transfer of metal contaminants. In the current “Anthropocene” epoch, metal contamination will continue to threaten marine aquatic ecosystems, and “non-traditional” isotopes can be a valuable tool to detect human-induced changes across time-space involving metal contaminants, and their interaction with marine biota.

Eco-toxic risk assessment and source distribution of trace metals in surface sediments of the coastal and in four rivers estuary of Sarawak

BackgroundTrace metals pollution in the coastal and estuarine sediment could harm water quality and aquatic organisms, leading to potential long-term health risks on the environment and humans. Thus, the purpose of this study was to conduct an assessment of selected trace metals in surface sediments of the coastal and in four rivers estuary in the Sarawak State of Malaysia to investigate their distribution, environmental risk, and potential source distribution.ResultsAverage concentrations of trace metals in sediment increased in the following order: Cd ˂ As ˂ Co ˂ Cu ˂ Ni ˂ Cr ˂ Zn ˂ Mn ˂ Mg ˂ Fe. The enrichment, contamination, and geo-accumulation index results showed that surface sediments were polluted with Zn and Mg. In contrast, the other metals (i.e., As, Fe, Mn, Ni, Cr, Cu, Co, and Cd) indicated background concentration to minor contamination. Generally, the pollution load index values showed that almost all the sampling sites were unpolluted with the selected trace metals. Sediment quality guidelines (SQGs) and risk indexes were employed to assess the ecotoxicological risk of trace metal contamination in the sediments. The results proved that studied trace metals are not likely to have a deleterious impact on bottom-dwelling organisms. Still, a further accumulation of trace metals such as Zn, Ni, and Cr with time may adversely affect bottom-dwelling organisms. The risk index results showed a low ecological risk to the study sites. The correlation analysis and principal component analysis indicated that nine studied trace metals have strong interrelationships, suggesting common pollution sources or similar geochemical characteristics.ConclusionsThe study highlights the need to make tremendous efforts to monitor and control trace metal pollution in the coastal and estuarine areas.

Heavy metal impression in surface sediments and factors governing the fate of macrobenthic communties in tropical estuarine ecosystem, India.

The present study aims to investigate the contamination of heavy metals in the sediments of a tropical ecosystem, India, and to evaluate the factors responsible for the dominance of specific macrobenthic communities, particularly in estuarine sediments. For the analysis of Cu, Cr, Ni, Zn, Pb and Cd in sediments, acid digestion and subsequent quantification by microwave plasma atomic emission spectroscopy was performed, whereas for Hg determination, cold vapour atomic absorption spectrophotometry was used. The general trend of the heavy metal concentration was observed as Cr > Cu > Zn > Ni > Pb > Cd > Hg, regardless of any seasonal alteration. The estuarine region was considerably contaminated by Cu and Cr (C.F. > 2) irrespective of any seasonal difference, and by Cd in 2017 non-monsoon (CF > 3). Heavy metal contamination was most pronounced during the monsoon (2018). Estuarine and marine zone together considered as deteriorated zone especially during monsoon seasons (PLI > 1, 2018 monsoon) while riverine zone remained poorly contaminated (PLI < 1). Clay Loam/Clay/Heavy Clay textures preferred polychaetes and bivalves in the estuarine and marine zone as compared to other macrobenthic communities (OMC). Among the hydrochemical parameters, total dissolved solids in general and euryhaline and slightly alkaline pH preferred domination of bivalves followed by polychaetes in non-monsoon seasons. The trace metal contamination in estuarine sediments increases the concern of bioaccumulation tendency of dominant bivalves of the estuarine and coastal sediments.

Impact of Zn substitution on Fe(II)-induced ferrihydrite transformation pathways

Iron oxide minerals are ubiquitous in soils, sediments, and aquatic systems and influence the fate and availability of trace metals. Ferrihydrite is a common iron oxide of nanoparticulate size and poor crystallinity, serving as a thermodynamically unstable precursor to more crystalline phases. While aging induces such phase transformations, these are accelerated by the presence of dissolved Fe(II). However, the impact of trace metals on Fe(II)-catalyzed ferrihydrite phase transformations at ambient temperatures and the associated effects on trace metal speciation has seen limited study. In the present work, phase transformations of ferrihydrite that contains the trace metal zinc in its structure were investigated during aging at ambient temperature in the presence of two different Fe(II) concentrations at pH 7. X-ray diffraction reveals that low Fe(II) concentration (0.2 mM) generates hematite plus minor lepidocrocite, whereas high Fe(II) concentration (1.0 mM) produces a magnetite-lepidocrocite mixture. In both cases, a substantial fraction of ferrihydrite remains after 12 days. In contrast, zinc-free ferrihydrite forms primarily lepidocrocite and goethite in the presence of 0.2 mM Fe(II), with minor hematite and a trace of ferrihydrite remaining. For 1.0 mM Fe(II), magnetite, goethite, and lepidocrocite form when zinc is absent, leaving no residual ferrihydrite. Transformations of zinc-ferrihydrite produce a transient release of zinc to solution, but this is nearly quantitatively removed into the mineral products after 1 h. Extended X-ray absorption fine structure spectroscopy suggests that zinc partitions into the newly formed phases, with a shift from tetrahedral to a mixture of tetrahedral and octahedral coordination in the 0.2 mM Fe(II) system and taking on a spinel-like local structure in the 1.0 mM Fe(II) reaction products. This work indicates that substituting elements in ferrihydrite may play a key role in promoting the formation of hematite in low temperature systems, such as soils or sediments. In addition, the retention of zinc in the products of ferrihydrite phase transformation shows that trace metal micronutrients and contaminants may not be mobilized under circumneutral conditions despite the formation of more crystalline iron oxides. Furthermore, mass balance requires that the abundance and isotopic composition of iron oxide-associated zinc, and possibly other trace metals, in the rock record may be retained during diagenetic phase transformations of ferrihydrite if catalyzed by dissolved Fe(II).

Study of trace metal contamination and ecological risk assessment in the sediments of a tropical river estuary, Southwestern India

The present study aims to assess the extent of trace metal pollution in the sediments of Sita-Swarna estuary, west coast of India, and investigate their possible ecological risk on the aquatic environment. The sediment cores were analyzed for sand, silt, clay, organic carbon, and trace metals (Al, Fe, Mn, As, Cd, Co, Zn, Pb, Ni, Cr, and Cu) at 2-cm intervals. The study revealed that sediments have deposited in relatively violent to very violent hydrodynamic energy conditions. Factor analysis indicated that the metal distribution is mainly controlled by Fe–Mn oxyhydroxides and organic carbon. Further, the geochemical approach, pollution indices, and statistical evaluation revealed moderate pollution in the catchment. From an ecotoxicological perspective, the estimated risk index (RI) value was found to less than 150, indicating low risk for aquatic life. Thus, this baseline study would help to adopt strategies in pollution control and protect the fragile marine environment.

Spatio-temporal accumulation patterns of trace metals in sediments of a large plateau lake (Erhai) in Southwest China and their relationship with human activities over the past century

Lake sediments are important archives of environmental changes and human activities, but the influences of human processes and lake spatial heterogeneity on the sedimentation of trace metals are still poorly understood. Based on 16 sediment cores from Lake Erhai (249 km2), trace metals (including As and Hg) contamination over the past century and the spatial heterogeneity and their response to the in-lake and in-watershed factors were explored. The elements were divided into two groups by cluster analysis: group I included As, Cd, Hg and Pb, and group II included Al, Fe, Ti, Cr, Cu, Ni and Zn. The element concentrations were generally stable in the low section of the cores, and started to increase since the 1980s for elements in group I, while element concentrations in group II generally decreased since the 1990s. Enrichment factor analyses identified group I elements as typical pollutants, and suggested that contamination started from the 1980s and reached maximum in the 2000s. Regional atmospheric deposition from ore mining and smelting was the main source, and anthropogenic As and Cd were also affected by watershed industrial discharges. Multi-core analyses indicated that spatial distributions and accumulation of As, Cd, Hg and Pb in the cores were affected by both human activities and sediment supply. Different from metal contamination pattern in surface sediments, high anthropogenic metal fluxes appeared in the central lake areas due to more sediment accumulation. Our study highlighted that reliable estimation of whole-lake pollutant inventories strongly relied on comprehensive analyses of multiple sediment cores and legacy input from the catchment.

Environmental impact of the historical slag pile at Davenport, Iowa, United States: Trace metal contamination in soils and terrestrial vegetation

Environmental impact of the historical slag pile at Davenport, Iowa, United States: Trace metal contamination in soils and terrestrial vegetation

Effects of bottom trawling on trace metal contamination of sediments along the submarine canyons of the Gulf of Palermo (southwestern Mediterranean)

Submarine canyons are preferential pathways for transport of particulate matter and contaminants from the shelf to the deep sea. The Gulf of Palermo continental margin has a very narrow shelf (about 2–3 km wide on average) and is incised by several submarine canyons that favour shelf-slope sediment transfer. A sediment core collected on the outer shelf and six sediment cores taken at different depths along the Oreto, Eleuterio and Anerella submarine canyons were analysed to study the transfer and historical record of trace metal contamination in the Gulf of Palermo continental margin. Trace metals, major elements, organic carbon and sediment grain size were analysed in these cores, which were dated with 210Pb to assess their historical compositional evolution since the late 19th century. Hg, Pb, Cu, Zn and Cd content increased until the 1970s and 1980s, associated with the increase in urbanization and industrial activities in the Palermo area, and Hg was the contaminant that reached the highest enrichments. However, the increasing trend of these metals contamination was reversed in the 1970s and 1980s, coinciding with drastic changes in the terrigenous content and grain size of sediments in the canyon axes. These changes occurred when bottom trawling fleets expanded to deeper fishing grounds equipped with powerful trawlers around the Gulf of Palermo canyon heads and flanks and along the Oreto canyon axis. Bottom trawlers have resuspended large amounts of sediment, which have been transferred into the canyons since the 1970s and 1980s and have thus increased sediment accumulation rates. This resuspended sediment has been mixing with the sediment transferred and accumulated along the canyons, diluting and reducing its trace metal contamination levels since the expansion of the bottom trawling fleets.

International Analysis of Sources and Human Health Risk Associated with Trace Metal Contaminants in Residential Indoor Dust.

People spend increasing amounts of time at home, yet the indoor home environment remains understudied in terms of potential exposure to toxic trace metals. We evaluated trace metal (and metalloid) concentrations (As, Cu, Cr, Mn, Ni, Pb, and Zn) and health risks in indoor dust from homes from 35 countries, along with a suite of potentially contributory residential characteristics. The objective was to determine trace metal source inputs and home environment conditions associated with increasing exposure risk across a range of international communities. For all countries, enrichments compared to global crustal values were Zn > Pb > Cu > As > Cr > Ni; with the greatest health risk from Cr, followed by As > Pb > Mn > Cu > Ni > Zn. Three main indoor dust sources were identified, with a Pb-Zn-As factor related to legacy Pb sources, a Zn-Cu factor reflecting building materials, and a Mn factor indicative of natural soil sources. Increasing home age was associated with greater Pb and As concentrations (5.0 and 0.48 mg/kg per year of home age, respectively), as were peeling paint and garden access. Therefore, these factors form important considerations for the development of evidence-based management strategies to reduce potential risks posed by indoor house dust. Recent findings indicate neurocognitive effects from low concentrations of metal exposures; hence, an understanding of the home exposome is vital.

Trace Metal Accumulation and Phytoremediation Potential of Four Crop Plants Cultivated on Pure Sewage Sludge

Phytoremediation is a viable strategy to remove trace metal contaminants from sewage sludge but still is poorly investigated. The aim of this study was to quantify the trace metal removal of B. napus, B. juncea, H. annuus, Z. mays grown on pure sewage sludge. Each species was grown on six different sewage sludge for 8 weeks and sludge were analysed for trace metal content and physico-chemical characteristics. Our results confirmed that all the tested sludge supported plant growth. The tested sludge showed a plant vigorousness lower (46% of sludge) or similar/increased (54% of sludge) compared to control treatment. B. juncea and B. napus were the most efficient species in the bioaccumulation, of trace metals. The average percentage of metals removed by the selected species was 0.2% for As, 0.85% for Cd, 0.09% for Cr, 0.36% for Cu, 0.36% for Ni, 4.2% for Se, 1.2% for Zn. In conclusion, our results showed that phytoremediation can be applied to sewage sludge, despite the chosen species have low efficiency in trace element removal. Further studies using hyperaccumulator species are needed which may lead to a higher efficiency of the process opening up new possibilities for the management strategies of this waste.

Trace Metal Contamination of Vegetables Grown Near the Tannery Estate in Savar, Bangladesh: Human Health Risk Assessment

Environmental pollution caused by tanneries is a long-term problem in Bangladesh. The present study investigated the levels of five globally alarming trace metals (Cd, Pb, Cu, Ni and Cr) in three commonly consumed leafy vegetables with corresponding soils (spinach – Spinacia oleracea ; broccoli – Brassica oleracea var-italica and stem amaranth – Amaranthus viridis), grown around the tannery estate in Savar, Bangladesh. Both in the soil and the vegetable samples, the observed trend of mean concentration of heavy metals was Cd&gt;Cr&gt;Cu&gt;Ni&gt;Pb. Excluding Cu and Cr in the vegetable samples, the level of all the studied metals in all the samples was higher than the maximum permissible limits set by the WHO. Plant transfer factor (PTF) was calculated in order to evaluate the metal uptake of the vegetables from the soil. PTF was found in increasing sequence of broccoli &gt; stem amaranth &gt; spinach and the trend of metal uptake found was, for spinach: Cu&gt;Pb&gt;Ni&gt;Cr&gt;Cd, for broccoli: Cu&gt;Cr&gt;Pb&gt;Ni&gt;Cd and for stem amaranth: Ni&gt;Cu&gt;Pb&gt;Cr&gt;Cd. Contamination factor (Cf) values revealed that the soil samples were highly contaminated by Cd. The values of the pollution load index (PLI) for spinach and stem amaranth were higher than 1, denoting the polluted state of the soil. To evaluate the potential health risk, target hazard quotient (THQ), hazard index (HI), and target cancer risk (TR) were analysed and the results showed that most of the values were significantly higher than the threshold values. This environmental assessment study should be of use during planning and management that aims to protect human health and the environment.

Contamination and ecological risk assessment of trace metals in surface sediments from coastal areas (El Jadida, Safi and Essaouira) along the Atlantic coast of Morocco

Concentrations of four trace metals (Cd, Cr, Cu and Zn) in surface sediments were quantified seasonally to evaluate the metal contamination and to determine the possible environmental risks at three coastal areas in northwest Morocco (El Jadida, Safi and Essaouira). Sampling was conducted quarterly at six intertidal stations with two stations per area (north to south: El Jadida: S1 vs. S2; Safi: S3 vs. S4 and Essaouira: S5 vs. S6). The trace metal concentrations were generally found to be greater in wet seasons for all sampling stations, and their mean values were arranged in the following decreasing order: Zn (28.35–136.10 μg g−1 dry weight) > Cr (6.50–130.90 μg g−1) > Cu (5.00–83.40 μg g−1) > Cd (0.02–5.95 μg g−1). As expected, the highest metal concentrations were recorded at stations exposed to the polluting point-source discharges from important industrial phosphate plants near El Jadida (S2-Jorf Lasfar) and Safi (S4-Jorf Lihoudi), which greatly exceeded the geochemical background values (Cd: 0.3 μg g−1 dry weight, Cr: 90 μg g−1, Cu: 45 μg g−1 and Zn: 95 μg g−1). All of the four trace metals were significantly correlated with each other, implying the same source of contamination and a similar pollution history. This was mainly derived from industrial waste generated by these huge phosphate industry plants. Meanwhile, results from hierarchical cluster analysis confirmed the findings from the correlations. This ecotoxicological evidence was primarily associated with untreated industrial discharge. The contamination Factor, degree of Contamination, and modified Degree of Contamination indices confirmed that these two stations were the metal contamination hotspots, and the most affected in this region, especially for Cd. Moreover, Pollution Load Index and Geo-accumulation Index reflected a spatial distribution of pollution following the decreasing sequence S4 > S2 > S1 > S6 > S3 > S5. Based on the Potential Ecological Risk Index, Cd concentrations indicated a moderate to very high potential ecological risk at all sampling stations, except at one pristine station S5 (Bhibeh). The spatial distribution of Mean-Effect Range Median-Quotient (M-ERM-Q) showed a negligible ecological risk at Cap Beddouza (S3) and Bhibeh. The mean values of Toxic Units (Σ TU) were found in the following decreasing order Cd > Cu > Cr > Zn, with a major contribution to the Σ TU coming from Cd (35.42%) and Cu (24.99%). Comparison of the current results with those found in other areas around the world revealed that the metal levels obtained here are in general low, except for Cd, which appeared to be in higher concentrations. Concentrations of Cd, Cr and Cu in sediments at S2 and S4 exceeded either the Threshold Effect Level of the Canadian sediment quality guidelines and Effect Range Low of the US National Oceanic and Atmospheric Administration, which demonstrated that these trace elements posed environmental risks while Zn appeared to present no environmental threat at all of the studied areas.

The spatial distribution of benthic foraminifera in the Pearl River Estuary, South China and its environmental significance

Thirty surface sediment samples were collected from the Pearl River Estuary, South China, and benthic foraminifera were analyzed in order to understand the relationship between foraminiferal assemblages and environmental parameters. Multivariate analyses showed that the foraminferal assemblages (i.e., abundance and diversity) are correlated with the hydro-sedimentary gradients within the estuary. In addition, the dominant faunal composition seems to be largely influenced by food availability and trace metal contamination in surface sediments. A comparison with historical data from 1980s demonstrated that the foraminiferal abundance and diversity in the lower estuary have dramatically decreased over the last three decades, together with a significant shift in the dominant species. This is most likely due to the cumulative impacts of eutrophication and Cu contamination caused by human activities in the Pearl River basin. This work confirms the value of benthic foraminifera as bio-indicators in polluted estuarine environments.

Metal Accumulation and Ion Regulation in the Fish Hyphessobrycon luetkenii Living in a Site Chronically Contaminated by Copper: Insights from Translocation Experiments.

Fish living in the João Dias creek (southern Brazil) have to deal with trace-metal contamination in the long-term basis, as this aquatic environment has been historically impacted by copper mining activities. In order to survive in this harsh environment, the local biota had to develop adaptations related to pollution tolerance. The aim of this study was to test if biochemical mechanisms related to osmoregulation were among these adaptations, using translocation experiments. Water ionic and trace-metal compositions were measured in a nonmetal impacted site (NMIS) and in a metal impacted site (MIS) of this creek. Also, whole-body metal accumulation, ion concentration and branchial enzyme activity (Na,K-ATPase and carbonic anhydrase) were evaluated in Hyphessobrycon luetkenii. In both NMIS and MIS, fish were collected and immediately stored, kept caged or translocated from sites. The result shows that waterborne Cu was 3.4-fold higher at the MIS. Accordingly, animals that had contact with this site showed elevated whole-body Cu levels. Moreover, both translocated groups showed elevated Na,K-ATPase activity. Additionally, fish translocated from the NMIS to the MIS showed lower carbonic anhydrase activity. These findings indicate that H. luetkenii chronically or acutely exposed to naturally elevated waterborne Cu showed a rapid Cu bioaccumulation but was unable to readily excrete it. Moreover, classic Cu osmoregulatory toxicity related to Na,K-ATPase inhibition was not observed. Conversely, impacts in ammonia excretion related to carbonic anhydrase inhibition may have occurred.

Ecological risk assessment of trace metals in sediment from the Old Brahmaputra River in Bangladesh

ABSTRACT The assessment of trace metal contamination in river sediments is crucial for suggesting effective strategies to protect aquatic ecosystem health. In this study, six toxic trace metals (As, Cd, Cr, Hg, Ni and Pb) in the surface sediments from the Old Brahmaputra River in Bangladesh were examined to evaluate the potential ecological risks. Sediment samples were collected in September 2018 and analysed by an atomic absorption spectrometer. Mean concentrations (mg/kg dw) of trace metals were in the order of Ni (43.49) > Cr (30.25) > Pb (14.29) > As (3.74) > Hg (0.16) > Cd (0.03). Spatially the sedimentary metals did not vary significantly. Source analyses revealed anthropogenic origin for most of the metals. The contamination factor, enrichment factor and geoaccumulation index (I geo) revealed a low degree of contamination for all cases except Hg, which showed a moderate degree of contamination. According to the sediment quality guidelines and sediment screening values, only Cr, Hg and Ni were high enough to cause detrimental effects in aquatic organisms. The potential ecological risk factor (Er i ) and potential ecological risk also revealed low to moderate ecological risk. Comprehensively, the river was in the uncontaminated to moderately contaminated level with low ecological risk.

Dynamics of Soil Microbial N-Cycling Strategies in Response to Cadmium Stress.

Globally increasing trace metal contamination of soils requires a better mechanistic understanding of metal-stress impacts on microbially mediated nutrient cycling. Herein, a 5-month laboratory experiment was employed to assess the effects of cadmium (Cd) on soil microbial N-cycling processes and associated functional gene abundance, with and without urea amendment. In non-N-amended soils, Cd progressively stimulated microbial populations for N acquisition from initial dissolved organic N (DON) to later recalcitrant organic N. The acceleration of N catabolism was synchronously coupled with C catabolism resulting in increased CO2/N2O fluxes and adenosine triphosphate (ATP) contents. The abundance of microbes deemed inefficient in N catabolism was gradually repressed after an initial stimulation period. We posit that enhanced exergonic N processes diminished the need for endergonic activities as a survival strategy for N communities experiencing metal stress. With urea amendment, Cd exhibited an initial stimulation effect on soil nitrification and a later a promotion effect on mineralization, along with an increase in the associated microbial populations. In N-amended soils, Cd accelerated N/C transformation processes, but decreased N2O and CO2 fluxes by 19 and 14%, respectively. This implies that under eutrophic conditions, Cd synchronously altered microbial C/N metabolism from a dominance of catabolic to anabolic processes. These results infer a nutrient-based adjustment of microbial N-cycling strategies to enhance their metal resistance.

Detection of Trace Metal Contamination Around a Dumpsite in Iyara Area Warri Nigeria Using Geoelectrical and Geochemical Methods

Trace metal concentration in soils of Iyara area of Warri, Delta State was studied using geophysical and geochemical techniques. Eight vertical electrical sounding (VES) using SAS 1000 Terrameter with maximum current electrode spread of 150 m in the Schlumberger configuration was carried out. The geoelectric layers obtained are topsoil, clay, sand and fine-medium grained sand. The fine to medium grained sand of the third and fourth layers mainly constitute the aquifer with a depth ranging from 4.8 - 11.0 m. Soil samples were collected at three of the VES stations covering the dumpsite and stations away from the dumpsite. The trace metal content was higher than the maximum allowable levels in soils as specified by the World Health Organisation (WHO) and Department of Petroleum Resources of Nigeria (DPR) except for Pb with undetected concentration in VES 3, Mn with 135 mg/kg in VES 1 and undetected in VES 3 and VES 7. The Multiple pollution index, Enrichment factor, and Non-carcinogenic hazard decreases with increasing distance from the dumpsite. The soil around the dumpsite has been impacted and the results of this study will serve as background information for soil studies and groundwater development in the area.

Health risk assessment of trace metals in selected food crops at Abuakwa South Municipal, Ghana.

Trace metals contamination has recently been a major issue due to its damaging effects on public health and environmental receptors. This study focussed on the health risk assessment of trace metals (As, Pb, Cr, and Ni) associated with the direct intake of some selected food crops (namely cocoyam and plantain) at Abuakwa South Municipal, Ghana. The food crops and soil samples were selected randomly from three reclaimed mined sites and one non-mining site in the study area. Results from the trace metal concentration analyses in the soil samples showed that As, Cr, and Ni were above the control. The daily intake of metals (DIM), target hazard quotient (THQ), and carcinogenic risk (CR) assessments of health risks accompanied by the continuous ingestion of the selected food crops polluted through these trace metals were evaluated. 0.23mg/kg and 0.05mg/kg, 0.11mg/kg and 0.02mg/kg, 0.78mg/kg and 0.65mg/kg, and 0.23mg/kg and 0.09mg/kg were recorded for As, Cr, Ni, and Pb in that order in the cocoyam and plantain, respectively. The As and Pb concentrations in the food crops were above the WHO recommended limits. This implies that individuals within the vicinity are exposed to high levels of As and Pb through food intake which could result in varying health implications. The DIM and THQ for the studied trace metals were below their permissible limits suggesting that there is a tolerable non-carcinogenic adverse health risk level for adults and children within the studied area. In addition, the lifetime probability of contracting cancer by ingesting Ni, Pb, and Cr in plantain grown in the study area is high. It is recommended that regular monitoring of these trace metals in food crops be carried out in preventing their excessive accumulation.

Source apportionment and human health risk assessment of trace metals and metalloids in surface soils of the Mugan Plain, the Republic of Azerbaijan

The Mugan Plain is the most productive area in the Republic of Azerbaijan, but a previous study confirmed trace metal and metalloid (TM&M) contamination with Cr, Ni and Pb, and the potential ecological risk of As was estimated. However, no industrial activity was previously reported in this area; thus, a source apportionment model using positive matrix factorization (PMF) was employed to identify pollution sources, and a human health risk assessment was conducted to evaluate noncarcinogenic and carcinogenic risks. Surface soil samples were collected from 349 sites, and six major elements (Si, Ca, Cl, P, S and Sr) and 8 TM&Ms (As, Cd, Cr, Co, Cu, Ni, Pb and Zn) were analyzed by X-ray fluorescence and employed for further apportionment and risk assessment. As a result, the PMF model showed 7 factors, assigned to natural activity (12.9%), dry riverbed (13.6%), surface accumulation (3.1%), desalinization activity (3.2%), residential activity (12.3%), fossil fuel combustion (35.5%) and agricultural activity (19.3%). The PMF model characterized certain areas with desalinization activity in the previous Soviet period and with surface accumulation of salt, and these findings were confirmed by additional field surveys and historical Landsat satellite images. The risk assessment results showed that there was no risk for the adults, while for children, there was a noncarcinogenic risk, but no carcinogenic risk. Dermal contact was estimated to be the primary pathway, and Ni and As were identified as the most problematic TM&Ms for noncarcinogenic and carcinogenic risks, respectively. According to the results, fossil fuel combustion associated with heating and vehicle transportation was estimated to be the main source of pollution, contributing 42.6% of the noncarcinogenic and 48.0% of the carcinogenic risks. These results can provide scientific guidance to understand and prevent the risk of TM&Ms on the Mugan Plain.