Spatial Distribution Of Trace Metals Research Articles

Mapping soil trace metal distribution using remote sensing and multivariate analysis.

Trace metal soil contamination poses significant risks to human health and ecosystems, necessitating thorough investigation and management strategies. Researchers have increasingly utilized advanced techniques like remote sensing (RS), geographic information systems (GIS), geostatistical analysis, and multivariate analysis to address this issue. RS tools play a crucial role in collecting spectral data aiding in the analysis of trace metal distribution in soil. Spectroscopy offers an effective understanding of environmental contamination by analyzing trace metal distribution in soil. The spatial distribution of trace metals in soil has been a key focus of these studies, with factors influencing this distribution identified as soil type, pH levels, organic matter content, land use patterns, and concentrations of trace metals. While progress has been made, further research is needed to fully recognize the potential of integrated geospatial imaging spectroscopy and multivariate statistical analysis for assessing trace metal distribution in soils. Future directions include mapping multivariate results in GIS, identifying specific anthropogenic sources, analyzing temporal trends, and exploring alternative multivariate analysis tools. In conclusion, this review highlights the significance of integrated GIS and multivariate analysis in addressing trace metal contamination in soils, advocating for continued research to enhance assessment and management strategies.

Field determination and ecological health risk assessment of trace metals in typical mariculture area of China

Field determination of dissolved trace metals (Cu, Pb and Cd) by using automated electrochemical system had been done in three typical mariculture areas of Yellow Sea (YS), East China Sea (ECS) and South China Sea (SCS) in China. Higher concentrations of Cu and Pb were found in ECS while the Cd concentration showed a decreasing trend from north to south of China. The metal distribution and ecological health risk assessments were also conducted. Cu and Pb in the YS and Cu in SCS were moderately contaminated. ECS had considerable Cu contamination and very high Pb contamination. Compared with other coastal areas, mariculture affected the concentration and spatial distribution of trace metals, but it was not a necessarily dominant factor. Overall, the results contribute to the further development of field and on-board metal detection technology and lay a foundation for the realization of field ecological health risk assessments of mariculture waters.

Spatial distribution of trace metals and associated transport proteins during bacterial infection.

Innate immune systems alter the concentrations of trace elements in host niches in response to invading pathogens during infection. This work reports the interplay between d-block metal ions and their associated biomolecules using hyphenated elemental techniques to spatially quantify both elemental distributions and the abundance of specific transport proteins. Here, lung tissues were collected for analyses from naïve and Streptococcus pneumoniae-infected mice fed on a zinc-restricted or zinc-supplemented diet. Spatiotemporal distributions of manganese (55Mn), iron (56Fe), copper (63Cu), and zinc (66Zn) were determined by quantitative laser ablation-inductively coupled plasma-mass spectrometry. The murine transport proteins ZIP8 and ZIP14, which are associated with zinc transport, were also imaged by incorporation of immunohistochemistry techniques into the analytical workflow. Collectively, this work demonstrates the potential of a single instrumental platform suitable for multiplex analyses of tissues and labelled antibodies to investigate complex elemental interactions at the host-pathogen interface. Further, these methods have the potential for broad application to investigations of biological pathways where concomitant measurement of elements and biomolecules is crucial to understand the basis of disease and aid in development of new therapeutic approaches.

Coral skeletons reveal the impacts of oil pollution on seawater chemistry in the northern South China Sea

Oil pollution can release trace metals (TMs) with cumulative toxicity into seawater, harming marine ecosystems in the long term. However, the lack of studies has inhibited our understanding of the effects and mechanisms of oil pollution on TMs in seawater. Hence, we investigated the 10-year monthly variation of TMs in Porites coral skeletons from the northern South China Sea (SCS), complemented by spatial distribution of TMs in seawater, sediments and characterization of TMs in fuel oil. The results of principal component-multivariate linear regression showed that the total contribution of oil pollution as a source to TMs in surface seawater was 77.2%, where the residence time of TMs (Ni, V, Cr, Co, Cu, Mn, Fe, and Mo) released from oil spills in surface seawater was approximately 1.4 months. Due to the geochemical nature of the metals, their seasonal variations are controlled by tropical cyclones (Ni, V, Cr, Co, Cu, Mn, Fe, and Mo), winter monsoons (Pb, Cd, Ba, and Zn) and sea surface temperature (Sr). This study shows that coral skeletons can be used as a new tool to study marine oil pollution. This provides valuable reference data for accurately identifying and quantifying the effects of oil pollution on TMs in seawater from a spatial and temporal perspective.

Spatial variation of cadmium concentration in the bivalve Beguina semiorbiculata (Linnaeus, 1758) from coastal coral reefs of Vietnam

The spatial distribution of trace metals (Fe, Zn, Cu, Cd, Mn, Pb and Ni) in the soft tissues of Beguina semiorbiculata from coastal reefs of Vietnam was studied. Bivalves were collected in May 2013 from 22 sites along the south-eastern coast from Gulf of Thailand to Ha Long Bay.The most increased concentrations of studied metals (excluding Cd) were shown in the B. semiorbiculata living in Ha Long Bay characterized by terrestrial runoff and anthropogenic effects. In contrast, the maximal Cd concentrations were found in the bivalves from coastal reefs of central Vietnam and Gulf of Thailand.Apparently, Cd concentration depends on seasonal upwellings (central part of Vietnam coast) and composition of suspended matter (Gulf of Thailand). Consequently, Cd distribution in the coastal waters of Vietnam should be strongly controlled in relation with predicted risk of climate change that may further significantly increased Cd bioavailability for habitants of coral reefs.

Impacts of the Residual Trace Metals of Aquaculture in Net Cages on the Quality of Sediment

Anthropogenic pollution by trace metals in aquatic environments in semiarid zones is a critical area of investigation. The objective of this study was to investigate the concentration and spatial distribution of trace metals in surface sediments in the Rosário reservoir, which is affected by the intensive aquaculture of Tilápia-do-Nilo (Oreochromis niloticus). Sediment samples were collected in three different areas, postculture (PCTV), cultivation (CTV) and control (CTRL) in the dry season in 2019. The granulometric composition, organic matter and concentrations of Fe, Mn, Zn, Cu, Cr, Cd, Pb and Ni metals were determined. Multivariate statistics were used. Geochemical and ecotoxicological indices and a comparison with sediment quality guidelines (SQG) were used. The sediment was characterized by silty clay loam with an average organic matter of 18.76 ± 4.27. The analytical merit figures demonstrated accuracy (metal recoveries in certified standards) between 89 to 99% and high precision (RSD < 5%). The concentration ranges for the metals were Fe: 0.11-0.85 (%), Mn: 14.46-86.91, Zn: 2.6-220.56, Cu: 26.89-98.75, Cr: 60.18-76.06, Cd: 0.38-0.59, Pb: 18.13-43.13, and Ni: 34.4-46.75, all in (mg/kg-1). The highest concentration values were found in the CTV areas (Fe: 40 ± 0.22, Mn: 66.48 ± 19.11, Zn: 114.83 ± 59.75 and Cr: 70.85 ± 2.62) and PCTV (Cd: 0.53 ± 0.04, Cu: 71.83 ± 21.20, Pb: 33.71 ± 4.34 and Ni: 44.60 ± 1.79). Pearson's correlation, hierarchical cluster analysis and principal component analysis confirmed the influence of fish farming on metals. Only Ni presented concentration values higher than the reference value established in the SQG. Thus, considering the probable geochemical and ecotoxicological effects, they comprise the two lowest levels of impact.

Geospatial assessment of variations in the heavy metals and pesticides concentration in the agricultural environment of Kasaragod District, Kerala, India.

The impact of heavy metals and pesticides in our environment largely varies based on their chemical composition and the geographical conditions where they are present. This study assesses the variation in the concentration of heavy metals and pesticides in Kasaragod District, Kerala, Southern India. For the assessment, soil samples were collected from eight different locations of agricultural land during the three different seasons of 2017 and 2018. All the samples were tested for physicochemical characteristics, levels of heavy metals, and pesticides. The spatial distribution of trace metals and pesticides in the study area was performed by using the software Arc GIS, version 10.6. Significant variation in the physicochemical properties was observed during the different seasons. Similarly, the variation in the concentration of heavy metals in the soil ranged from 0.01 to 1018 [Formula: see text]g/kg. Among various heavy metals detected, aluminum (Al) was the most abundantly detected metal in the region of Malakallu, and cobalt (Co) was the scarcely detected metal in the region of Panathady. The average levels of organochlorine pesticides (OCPs) and organophosphorus pesticides (OPs) in the soil samples were from below detectable level (bdl) to 610 [Formula: see text]g/kg and bdl to 441 [Formula: see text]g/kg respectively. Thus, our study indicates the continuous occurrence and persistent nature of contaminants in the agricultural soil of Kasaragod. Therefore, periodic monitoring of soil contaminants is recommended in Kasaragod to assess its effect on the ecosystem and to develop an effective remediation strategy.

Distribution of trace metals and radionuclides contamination in two sections of sediment cores from the Nyong estuary, Cameroon, southern Atlantic coast

This study investigated the spatial distribution of trace metals (Fe, Mn, Ni, Cr, Co, Sc and V) and radionuclides (Th and U) contamination in surface and bottom sediments from the Nyong estuary, Cameroon southern Atlantic coast, to provide informations on the pollution status of these sediments and the possible sources of pollutants. Salinity were measured in situ in interstitial water and dried sediment were analyzed for grain size parameters and geochemical composition. Salinity decreases from downstream to upstream, with 19.88 PSU as the highest value and sand is the main constituent (79.25 %). The concentrations of these elements varied significantly among depth (surface and bottom section), with a preferential contribution from the surface. In this surface section, several elements (Fe, Mn, Co, Sc and V) contributed about 80 % to the distribution of each of them in the estuary. Enrichment Factor (EF), Geo-accumulation Index (Igeo) and Contamination Factor (CF) of Nyong estuary surface sediments revealed a moderate pollution, while bottom sediment were unpolluted to moderate polluted. The pollution load index (PLI) show that surface sediments (3.86) and bottom sediments (1.19) are polluted. Pearson correlation and component principal analysis confirmed the natural origin of selected elements (Fe, Mn, Ni, Cr, Co, Sc, V, Th and U) through the weathering and the erosion of sources rocks. However, Pearson correlation analysis and the high Ni (3.91) and Cr (3.54) EF values in bottom sediments suggest a reception of other contaminants from the same emission sources or similar sources, may be agronomic inputs.

Identification of pollution sources and spatial distribution of trace metals in soils of the industrial area El Hadjar (Annaba, Algeria)

ABSTRACT The purpose of this study is to investigate trace metal contents in soils, to determine their spatial distribution, and to identify their potential natural either anthropogenic sources using multivariate statistical approaches. Soils were taken in the industrial area of El Hadjar (NE-Algeria) at 0-10 and 10-20 cm. The results revealed an order of Fe > Zn > Pb > Cu > Cr, whatever the depth. Mean concentrations of Fe, Zn, Pb, Cu and Cr were 31191, 219.87, 96.76, 47.87, 28.27 µg/g, respectively, at 0-10 cm, and 29,792, 304.09, 115.45, 49.08, 28.16 µg/g, at 10-20 cm. Cr and Fe mean concentrations were below or close to soils worldwide backgrounds. These metals perhaps principally derive from natural sources. The percentages of sites with Zn, Pb and Cu contents over the background values were: 88.23% (Zn) > 82.35% (Pb) > 52.94% (Cu) at 0-10 cm, and 94.11% (Zn) > 88.23% (Pb) > 41.17% (Cu) at 10-20 cm. Hotspot areas of metal contamination were mainly concentrated around the Arcelor Mittal complex which seems to be the strongest effect factor influencing the spatial distributions of these metals. Results of this study suggest that Cr and Fe are predominantly derived from natural sources; Pb and Zn from industrial sources; and Cu from agricultural and industrial ones.

Dam construction attenuates trace metal contamination in water through increased sedimentation in the Three Gorges Reservoir

Dam construction has a far-reaching impact on trace metal accumulation and the metal-induced quality of the aquatic environment. However, the long-term impacts of dam construction and impoundments on the spatial distribution of trace metals and water quality remain poorly understood. Here, we found that the concentrations of trace metals in the mainstream water of the world's largest reservoir, Three Gorges Reservoir (TGR), decreased after impoundment, while their concentrations and contamination in the sediments of the water-level fluctuation zone increased significantly, especially for anthropogenic sources of metals such as cadmium, lead, and zinc. The spatial and temporal variations of anthropogenic metals in the sediments revealed increased anthropogenic dominance in their distribution under current hydrological management, especially for the urban area of the upper TGR. Sediment fluxes, particle composition, and extreme climate modulated the distribution of trace metals in the sediments. The results demonstrate that human activities have increasingly determined the distribution and contamination state of trace metals in the mainstream TGR. However, in contrast to our previously thought, the anthropogenic discharge of trace metals did not adversely affect water quality. Our results indicate that dam construction in riverine systems attenuates trace metal contamination in water through sediment sorting and deposition.

Environmental risk of trace metals and metalloids in estuarine sediments: An example from Southampton Water, U.K.

Industrial and commercial port activities are widely recognized worldwide as an important source of pollution to proximal estuaries. In this study, we analysed geochemical and sedimentological parameters including major and trace elements, organic matter and sediment texture in surface sediments from the estuarine environment of Southampton Water, U.K. Using these data, and multivariate statistical tools [correlation, factor and cluster analysis and pollution indices such as Enrichment Factor (EF), Pollution Load Index (PLI) and the Adverse Effect Index (AEI)], we examine sedimentary trace metal and metalloid contamination, contamination sources, and potential biological impacts of the contamination present. The geochemical data, multivariate statistical analysis and pollution indices indicate that the spatial distribution of trace metals and metalloids is influenced by both sediment composition (and mixing) and anthropogenic activities. Most trace metal and metalloid concentrations are close to local geological background levels, except for Cu, Zn and Pb. The spatial distribution of these elements indicates that the Exxon oil refinery, Southampton port, local marinas and runoff from domestic and industrial activities act effectively as point sources of these elements. Pollution indices calculations highlight a degraded environment as a result of these pollutants, and further work is needed to assess the current impact of trace metals and metalloids on local ecology.

Occurrence and spatial distribution of trace metals in seawaters of the Drake Passage and Antarctic Peninsula

In this study, surface seawater was collected from 82 stations in the Drake Passage and Antarctic Peninsula sea area, and the distribution characteristics and correlations of 11 trace elements (i.e., V, Cr, Mn, Co, Cu, Zn, As, Mo, Cd, Pb, and U) in the seawater were analyzed. Results showed remarkable differences in the concentration of different elements, among which those of Mn (53.15%), Mo (22.77%), Zn (9.81%), and U (6.23%) were relatively high. The concentration of trace elements in Drake Passage water was relatively low, likely because a westerly drift that enhances large circulating currents exists in the sea area, thereby affecting the distribution of substances in the water. Mn, Co, Cu, Zn, Cd, and Pb showed relatively high concentrations at more stations than the other elements, and the high concentrations of Mn, Co, and Cd were mainly found in shallow water areas. UV, MoV, AsV, AsMo, AsU, and MoU demonstrated good linear correlations with correlation coefficients in the range of 0.878–0.961. These results could provide support for further explorations of the environmental behavior of trace elements in Antarctica.

Controls on the Spatial Distribution of Trace Metal Concentrations along the Bedrock-Dominated South Fork New River, North Carolina

In marked contrast to alluvial rivers, few studies have examined the physical and geochemical controls on the spatial distribution of toxic trace metals along bedrock channels. This study examined the factors controlling the geographical pattern of selected trace metal (Cu, Cr, and Zn) concentrations along the bedrock-dominated channel of the South Fork New River (SFNR). The SFNR is located in the Blue Ridge Physiographic Province of North Carolina, and is representative of many rivers in mountainous terrains that are often subjected to the influx of toxic trace metals from historic and contemporary mining operations. The topography of the SFNR’s channel bed is highly variable and can be subdivided into pool and shallow bedrock reaches. The latter contained localized cascades characterized by topographically higher bedrock ribs that are separated by topographic lows, both of which are oriented oblique to flow. Accumulations of bed sediments are predominantly associated with the traverse bedrock ribs that generate high hydraulic roughness. Except for a few localized zones of enrichment, sediment-associated trace metal concentrations tended to vary within a narrow range of background values over the 36 km study reach. Elevated trace metal concentrations were closely linked to zones of high Fe and Mn concentrations, and were associated with pools located within or immediately downstream of bedrock cascades. The elevated concentrations of the metals appear to be derived from the erosion of lithologic units within the cascades that contain sulfidic layers or zones of mafic mineral enrichment, and which are known to occur in the underlying bedrock. Once eroded, these minerals and/or rock fragments were deposited within low-velocity zones created by the transverse ribs or within downstream pools. The enrichment of trace metals downstream of the cascades may also be due to the formation of Fe and Mn oxyhydroxides as turbulent flows aerate river waters as they traverse the cascades. Chemically reactive fine-grained (&lt;63 µm) sediments had a relatively limited influence on the downstream variations in metal concentrations, presumably because the channel bed sediments are composed primarily of sand-sized and larger particles. Although a principal component analysis (PCA) suggested that reach-scale variations in channel and valley morphology may have partly influenced downstream variations in trace metal concentrations, the geographical patterns were primarily controlled by local geological and geomorphic factors associated with the bedrock cascades. The design of future sampling programs along such coarse-grained, bedrock rivers should consider the significance of these local controls on trace metal storage to effectively characterize and interpret downstream patterns in metal concentrations.

Longitudinal patterns in sediment type and quality during daily flow regimes and following natural hazards in an urban estuary: a Hurricane Harvey retrospective

Understanding the transport of sediments in urban estuaries and their effects on water quality and microorganisms is a convergent challenge that has yet to be addressed especially as a result of natural hazards that affect the hydrodynamics of estuarine systems. This study provides a holistic view of the longitudinal nature and character of sediment in an urban estuary, the Galveston Bay Estuary System (GBES), under daily and extreme flow regimes and presents the results of water and sediment sampling after Hurricane Harvey. The sediment sampling quantified total suspended sediment (TSS) concentrations, metal concentrations, and the diversity of microbial communities. The results revealed the impact of the substantial sediment loads that were transported into the GBES in terms of sediment grain type, the spatial distribution of trace metals, and the diversity of microbial communities. A measurable shift in the percentage of silt relative to historical norms was noted in the GBES after Hurricane Harvey. Not only did sediment metal data confirms this shift and its ensuing impact on metal concentrations; microbial data provided ample evidence of the effect of leaks and spills from wastewater treatment plants, superfund sites, and industrial runoff on microbial diversity. The research demonstrates the importance of understanding longitudinal sediment transport and deposition in estuarine systems under daily flow regimes but more critically, following natural hazard events to ensure sustainability and resilience of systems such as the GBES that encounter numerous acute and chronic stresses.

Environmental Assessment of Heavy Metals in Soil of West Quarna -2 Oil field at Basrah-Southern Iraq

In this study, concentrations of eight heavy metals (Pb, Ni, Cu, Cr, Zn, Co, Cd and Fe) wereinvestigated during 2016 in ten stations at West Qurna-2 oil field in Basra city Southern of Iraq. Thesemetals were analyzed by using Atomic absorption spectrometry. The mean values of the metals in thesoil range for : pb (18.23 -39.15), Ni (28.34-46.35), Cu (10.12-18.22), Cr (50.64-59.23), Zn (25.23-40.48), Co (5.34-11.27), Cd (5.99-10.23) and Fe (1150.12-2185.83) ug/g dry weight. ContaminationFactor (CF), Enrichment factor (EF) and Geo accumulation index (I-geo) were computed and comparedin different stations of the soil oil field. Total concentration of metals in soil samples found to be in thisorder: Fe&gt;Cr&gt; Ni &gt;Zn&gt; Pb&gt;Cu&gt; Co&gt;Cd. The main reason for different in concentration could be dueto the effects of contamination caused by various activities in the oil field and the urban .Total organiccarbons and grain size analysis were also determined, and there is a good correlation between TOC andHeavy metals. These data are a first of its kind in this important area and could be used as a baseline forcoming study in the futures.The purpose of this study were to determine the spatial distribution of trace metals in the soil of theWest Qurna-2 oil field, and to quantify potentially ecological risk of trace metal pollution.

A baseline study on trace metals concentration and its ecological risk assessment from the coast of South Andaman Island, India

The rapid urbanization processes in island coastal areas has led to serious pollution in the marine environment. Less is known about the trace metal speciation and ecological risk (ER) in the coastal sediments of island areas under various human activities pressures, which is essential to address the connection between metal pollution and anthropogenic impacts. We report here the trace metals concentration and its ecological risk on the coast of South Andaman Island (SAI). A total of 23 study locations were selected (March 2013) and the surface sediments were studied for trace metal concentrations such as Iron (Fe), Manganese (Mn), Chromium (Cr), Cobalt (Co), Copper (Cu), Nickel (Ni), Arsenic (As), Zinc (Zn), and Lead (Pb). Moreover, the marine pollution indices such as Enrichment Factors (EFs), Geo-accumulation Index (Igeo), Contamination Factor (CF), Pollution Load Index (PLI), and Sediment Pollution Index (SPI) were also studied to consider the spatial distribution of trace metals. The concentration values of trace elements are found in the order of Fe > Mn > Cr > Ni > Zn > Cu > Co > Pb > As. The CF analysis suggested that the South Andaman coastal sediments are a relatively significant level of elements contamination. Besides the EF and Igeo values also showed significant enrichment in the nearby settlement area and indicated that the study locations are coming under unpolluted and moderately polluted categories. The PLI and SPI analyses showed that the inner Bay region (stations 1, 2, 3, and 20) of Port Blair Bay is a highly polluted area and its ER values suggest that the sediments fall under the moderate risk (69.56%) and considerable risk (30.43%) categories. The statistical analysis clearly indicated that the accumulations of trace elements in the study locations are due to anthropogenic inputs from the adjacent land-based sources. Spatial data on the heavy metal concentration of the studied site would help the policymaker/environmental managers to identify the vulnerability site and take appropriate remedial effort to protect the pristine island coastal ecosystem.

Ecological risk assessment of trace metals and comprehensive contamination indicators in the coastal waters of Macao, South China Sea

Few systematic and scientific assessments have been conducted on marine environmental quality in the coastal waters of Macao, a major city in the Pearl River Delta, China. In this study, we investigated the spatial distribution of trace metals (TMs) and comprehensive contamination indicators of marine water in Macao and evaluated their ecological risks. The total amount of typical TMs (∑TMs) in surface water ranged from 2.71 μg/L to 201 μg/L. ∑TMs (Hg, As, and Cd) in sediments ranged from 0.34 mg/kg to 54.8 mg/kg. TM contamination in surface water was influenced by spatial position and tidal current direction. The spatial distribution and correlation analysis of TMs and comprehensive contamination indicators were assessed, and ecological risk assessment indicated that the surface water and sediments in coastal waters of Macao are of relatively good quality, although high sulfide levels could be detected in surface water.

Hydrodynamic impact on trace metals in sediments in the cascade reservoirs, North China.

Cascade reservoirs facilitate the effective use of water resources and help to alleviate existing problems of water shortage in drought-prone regions. However, the geochemical behavior and controlling mechanisms of trace metals in response to the operation of cascade reservoirs are relatively unknown. Here, trace metals (As, Cr, Cu, Li, Ni, Pb and Zn) from thirty sediment cores from cascade reservoirs (Panjiakou and Daheiting Reservoirs) in China were evaluated. Multiple methods including geochemical baseline, geostatistical analysis, factor analysis (FA), and positive matrix factorization (PMF), were combined to assess pollution status, identify and quantify potential anthropogenic sources, and determine the influence of hydrodynamic conditions on trace metals distribution. The results indicate that minor enrichment of trace metals appeared in both cascade reservoirs. However, trace metal concentrations exhibited spatial heterogeneity between two cascade reservoirs, and diverse hotspots of different metals were unexpectedly observed. This can be explained by the following three aspects: (1) Metal hotspots were detected upstream of the cascade dams via geostatistical analysis and FA, particularly for naturally sourced metals (As and Li) where dam interception resulted in higher concentrations in the upstream reservoir. (2) PMF analysis identified agricultural, industrial, and natural sources to account for 23.44%, 41.61%, and 34.95%, respectively, to the metal concentrations in the downstream reservoir. Anthropogenic emissions were the dominant factors influencing the spatial variability of Cu, Pb, and Zn between the cascade reservoirs, with higher concentrations observed in the downstream reservoir. (3) The hydrological regime also influenced the redistribution of human-derived metals, where slower flow velocities at river bends resulted in higher deposition of metal-bearing particles. This study shed light on the spatial distribution of trace metals in response to the construction and operation of cascade reservoirs, and it suggests that trace metal hotspots should be monitored to prevent potential contamination in sediments.

Chronic Kidney Disease of undetermined cause (CKDu), an emerging disease in developing nations

OPS 25: Drinking water contamination and adult health, Room 411, Floor 4, August 26, 2019, 10:30 AM - 12:00 PM Background: There is increasing recognition of epidemics of primarily tubular-interstitial chronic kidney disease (CKD) clustering amongst working-age populations in agricultural communities in low-and-middle-income countries. These conditions have been termed CKD of undetermined cause (CKDu) due to unidentified underlying aetiology. Hypothesised causes include heat stress and heavy metal exposure through potable water. Our aim was to investigate CKDu presence in Malawi, and identify potential risk factors including nephrotoxic heavy metals in potable drinking water. Methods: Blood and urine samples (n=770) taken from an urban and rural study site (January-August 2018) were used to estimate kidney function across the sample population. We applied linear and logistic regression models with postulated risk factors including age, sex, education, residence, vegetarianism, and body mass index to estimate risk of low glomerular filtration rate (eGFR) (<90 ml/min/1.73m2). We collected potable water samples which were tested for trace metals by Nottingham University. We analysed the spatial distribution of trace metals across the study area using inverse distance weighting with standardised z-scores. Results: Mean eGFR was 117.1±15.83ml/min/1.73m2. Prevalence of low eGFR was 5% (95%CI = 3.0, 6.2), and did not vary substantially between sites. Factors associated with low eGFR included low income (<10,000 Malawian Kwacha) [OR (95%CI) = 0.16 (0.02, 1.07)]; and age [4.87 (0.39, 6.00)] per 10-year increase. Mean trace metal concentrations did not exceed permissible limits. However, some sites contained nephrotoxic metal concentrations which neared limits, including Cadmium (2.66µg/L, World Health Organisation limit 3.00µg/L). Conclusions: Reduced kidney function in the absence of known risk factors (eGFR <90 ml/min/1.73m2) was observed across our study area, however little difference in risk between sites was observed. No known nephrotoxic trace metals exceeded permissible limits, however, analyses of heavy metals concentrations in bio samples will be conducted to rule these out as risk factors for reduced kidney function in Malawi.

Distribution and risk assessment of trace metals in multifarious matrices of Vembanad Lake system, Peninsular India

Trace metal contamination in aquatic ecosystems is of significant concern in countries like India having a recent industrial history. The present study mainly focuses on the spatial and temporal distribution, occurrence and toxicity of five trace metals (Hg, Cd, Zn, Cu and Pb) in water and sediment matrix of Vembanad Lake system (VLS), India. Mercury analysis was done by using Cold Vapor Atomic Fluorescence Spectrometer, and the other metals were analysed using Volta metric-Trace metal analyser. The spatial distribution of trace metals in the study area showed the following trends, Zn > Pb > Cu > Cd > Hg, Zn > Pb > Cu > Hg > Cd for surface water and bottom water respectively. Health risk assessment on human population associated with trace metals was also calculated to predict their health impacts on human through non-dietary exposure. The trace metals contamination in water and sediments of VLS are potential to cause cancer on human population associated with the system. Ecological risk indices showed that the northern portion of VLS is more contaminated with trace metal than the other part of the system.