Trace metal distribution in Tilapia zillii and Synodontis schall from the Siluko River, Edo State, Nigeria

Aquaculture contribution to human nutrition, consumers’ preferential bias towards capture fisheries and concerns on food safety has necessitated the need for information on the nutritional composition of fish species from diverse settings such as geographical locations and aquaculture rearing facilities. This study determined the nutritional profile and associated human health risk of adult size African catfish (Clarias gariepinus) cultured in plastic tanks with those harvested from the wild. Results showed the mean protein (18.04%) and lipid (8.71%) values of cultured C. gariepinus were significantly higher than reported values in C. gariepinus from the wild, which makes them of more nutritional value to consumers. Captured fishes reported higher ash, mineral and trace metal contents, which was attributed to the elevated levels of these elements in their habitat waters due to water pollution. Low metal pollution index (MPI) values in cultured and captured fishes indicated an insignificant bioaccumulation of trace metals, and the absence of non – carcinogenic (HI <1) and carcinogenic (ICR < 1 × 10−6) risk associated with their consumption. Although the captured fishes at present poses no health risk to consumers; their recorded higher contents of trace metals, MPI, HI and CPI values is a cause for concern on the safe consumption of capture fishes. With increasing concerns on aquatic food safety, this study has shown that the consumption of cultured C. gariepinus provides more nutritional quality to consumers. The need for more monitoring studies on different culturing methods and settings on the nutritional composition and food safety is recommended.

This study was executed to investigate the acidification and heavy metal (Cr, Mn, Fe, Ni, Cu, Zn, and Pb) pollution of Tohma stream flowing near Kangal lignite-fired thermal power plant located in Kangal district of Sivas province in the Central Anatolia region of Turkey. All water samples were screened for pH to evaluate the acidification of the Tohma stream. Water samples were found in moderately alkaline according to pH values (8.1–8.7). The average concentrations of Cr, Mn, Fe, Ni, Cu, Zn and Pb in water samples from the Tohma stream were determined as 0.94, 2.27, 13.78, 1.24, 1.98, 0.32 and 0.54 mg L−1 using energy dispersive X-ray fluorescence spectroscopy, respectively. Metal pollution index (MPI) and metal evaluation index (MEI) were estimated to evaluate the pollution of Tohma water samples with heavy metals. The values of MPI and MEI varied from 312 (medium pollution) to 9715 (high pollution) with an average of 4713 (high pollution) and 181(medium pollution) to 317 (high pollution) with an average of 226 (medium pollution), respectively. The results of MPI and MEI revealed that investigated water samples are seriously polluted with toxic heavy metals and inadequate for drinking and irrigation water utilisation.

ABSTRACTWe examined the temporal variation of heavy metals in different sexes of three brackish water shrimp species with emphasis on the relationship between Fulton's K condition indices and metal pollution index (MPI). Zn was the most abundant metal followed by Sn, though levels were below the admissible limits (irrespective of gender). Temporal variation of Zn and Pb was significant (p < 0.01). Drier weather conditions influenced Pb accumulation. Temporal variation of Sn was insignificant (p > 0.05), but temporal variation of Hg was significant only in Penaeus monodon (p < 0.0001). However, the relationship between temporal variation of the above-mentioned metals and gender was insignificant except in Penaeus semisulcatus for Pb (p < 0.02) and Sn (p < 0.04) despite no consistent higher bioaccumulation pattern by one particular sex. There were no significant negative correlations between the Fulton's K condition indices and MPI values in the different sexes. MPI values between the two sexes were insignificant. Any differences in the MPI values between the three species were insignificant. Only Penaeus semisulcatus exhibited significant differences (p < 0.022) in Fulton's K condition indices in relation to gender. Fulton's K condition indices are unreliable indicators of metal-induced stress levels in shrimps.

Background: This study examines the contamination of Sarotherodon melanotheron (tilapia) by trace metal elements, cadmium (Cd), mercury (Hg), and lead (Pb), in the Grande Niaye of Pikine Urban Nature Reserve and its Dependencies (UNRGNPD), a highly anthropized urban aquatic ecosystem in Dakar, Senegal. Objectives: The primary aim is to quantify heavy metal concentrations in tilapia tissue and to assess the toxicological risks posed to human health through their consumption. Methods: Fish samples were collected during the dry and rainy seasons of 2021 and 2022. Concentrations of Cd, Hg, and Pb in muscle tissue were determined using atomic absorption spectrometry. The Metal Pollution Index (MPI) was used to evaluate the overall level of contamination, while the Target Hazard Quotient (THQ) was calculated to assess potential health risks for adult and child consumers. Results: Heavy metal concentrations were particularly elevated during the rainy season, often exceeding international safety limits set by the FAO/WHO. MPI values indicated significant seasonal and interannual variation, with 2021 showing the highest levels of contamination. THQ values for Cd and Hg exceeded 1, especially in children, indicating a substantial non-carcinogenic health risk. Conclusion: These findings underscore a serious environmental and public health concern. Urgent intervention is needed to mitigate metal pollution through stricter regulation of industrial and domestic effluents, improved wastewater treatment infrastructure, and community education regarding the risks of consuming contaminated fish.

Trace metals(As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Pb and Zn) concentrations in surface sediments of Jinhae bay in August of 2013 were measured to investigate the characteristics of trace metals distribution and to evaluate the metal pollution. Assessment for metal pollution was carried out using the sediment quality guidelines(SQGs) such as threshold effects level(TEL) and probable effects level(PEL) proposed by the ministry of onceans and fisheries(MOF) in Korea and geochemical assessment techniques(enrichment factor(EF) and geoaccumulation index ()). The mean concentration of trace metals in the sediments are as follows: 11.1 mg/kg for As, 0.52 mg/kg for Cd, 14.1 mg/kg for Co, 69.8 mg/kg for Cr, 57.2 mg/kg for Cu, 3.7 % for Fe, 0.064 mg/kg for Hg, 600 mg/kg for Mn, 40.1 mg/kg for Pb, 167.2 mg/kg for Zn. The spatial distributions of As, Co, Cr and Fe were not distinguished clearly in whole area. However, Cd, Hg, Pb and Zn were high in northern area of bay, and Cu and Mn were high in southeastern and eastern area of bay, respectively. The distribution pattern of trace metals, correlation matrix and R-mode factor analyses results revealed that the distribution of trace metals were mainly effected by the sediment grain size(Co, Cr and Fe), redox condition of sediments(Mn) and anthropogenic factors(As, Cd, Cu, Hg, Pb and Zn). Comparing the concentrations of several trace metals(As, Cd, Cr, Hg and Pb) with SQGs from Korea(TEL and PEL), the concentrations of Hg, Cd and Pb in sediment of northern area of bay were higher than TEL. EF and values of As, Cd, Cu, Hg, Mn, Pb and Zn showed that these metals in sediments are enriched by anthropogenic activities in some areas, and pollution status for Cd, Hg and Pb in northern area and Cu in southeastern area of bay were concerned about current level, although those for As, Mn and Zn were not.

Toxic metal pollution and ecological risk assessment in water and sediment at ship breaking sites in the Bay of Bengal Coast, Bangladesh

Soil, rock and water samples were collected from India's oldest coalfield Raniganj to investigate trace metal contamination from mining activity. Our data reveal that trace metal concentration in soil samples lies above the average world soil composition; especially, Cr, Cu, Ni and Zn concentrations exceed the maximum allowable concentration proposed by the European Commission for agricultural soils. In particular, Cr, Cu and Ni exceed the ecotoxicological limit, and Ni exceeds the typical value for cultivated soils. Mineral dissolution from overburden material and high adsorption capacity of laterite soil are responsible for the elevated concentrations. This is evident from enrichment factor (E (f)), geoaccumulation index (I (geo)) and metal pollution index values. Sediment quality guideline index indicates toxicity to local biota although enrichment index suggests no threat from consuming crops cultivated in the contaminated soil.

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.

Assessment of trace metals concentrations in zooplankton from the Edremit Bay (Northeastern Aegean Sea, Türkiye)

Urban wetlands are often polluted by heavy and trace metals being discharged from industries, urbanisation and agriculture, which tend to alter the sediment quality. Sediments are important as they act as a sink for nutrients in aquatic environments. Wetlands play an important role in maintaining ecological balance, preventing floods and droughts, providing shelter for various animals and plants and supporting human well-being through essential services such as carbon sequestration and water purification. The present study aimed to assess the spatiotemporal distribution and sediment pollution indices of trace and heavy metals in surface sediments and identify potential sources of contamination in urbanised Austral wetlands. Sediment samples were collected within the Riverside’s Wetlands, City of Nelspruit, South Africa, across three seasons (i.e. hot–dry, hot–wet and cool–dry seasons). A multivariate principal component analysis was used to determine the metal relationship. The metal pollution indices, such as contamination factor, enrichment factor, geo-accumulation factor and pollution load index were used to determine the pollution of metals in the sediments across different sites among seasons. The study found that only the lower Na concentration was observed during the cool-dry season, which was lower compared to the concentrations of other metals. The pollution indices indicated that wetland sediments were highly contaminated, mainly with Mn, Co, Cu, Pb, Zn, Al and Fe, especially during the cool–dry season. The current study highlights an urgent need to come up with immediate measures to control severe heavy metal pollution from the industrial emission into the wetlands. Those immediate measures should be carried out to minimise the rate of contamination and extent of future metal contamination.

In recent years, intensified industrialization and rapid urbanization have accelerated the accumulation of trace metals in topsoils of the Golden Triangle of Southern Fujian Province in China. Trace metals can cause adverse impacts on ecosystems and human health. In order to assess the ecological and human health risks of trace metals in the Golden Triangle region and to determine the distribution and degree of pollution of trace metals, 456 soil samples were collected from 28 districts. The concentrations of six metals (As, Cr, Cu, Ni, Pb, and Zn) were analyzed to assess ecological risk using the geoaccumulation index (Igeo) and the potential ecological risk index (RI). The United States Environmental Protection Agency (USEPA) model was applied to calculate health risk. The average soil concentrations of the six elements are ranked as follows: As < Ni < Cu < Cr < Pb < Zn. Inverse distance weighting (IDW) interpolation maps showed that Cr, Cu, Ni, and Zn are enriched in the soils of developed areas, while As and Pb are enriched in the soils of undeveloped areas. The Igeo showed that the levels of metals in most soil samples are below polluting levels. Similarly, RI values indicated that trace metals pose low potential ecological risk in the region’s soils. The Hazard Quotient (HQ) ranked the mean total noncarcinogenic risk of the six metals, for both children and adults, as follows: As > Pb > Cr > Ni > Cu >Zn. The mean carcinogenic risk (CR) of the metals in the region’s soils are ranked as follows: Cr > As > Ni. The Hazard Index (HI) values indicated that 3.7% of soils contained unsafe levels of toxic metals for children and total carcinogenic risk (TCR) values indicated that 23.3% of soils contained unsafe levels, indicating that children are facing both noncarcinogenic and carcinogenic risks from trace metals. Principal component analysis (PCA) and matrix cluster analysis were used to identify pollution sources and classified trace metals and soil samples into two and five groups, respectively. The five groups represented the effects of different land use types, including agricultural area, residential and public area, industrial area, forest, and industrial area and roadside, based on the contents of trace metals in soils. Industrial, agricultural and traffic activities attribute to the enrichment of Cr, Cu, Ni, Pb, and Zn in the region’s soils. Moreover, the accumulation of As and Pb are also attributed to atmospheric deposition. These results can contribute to a better understanding of pollution, ecological risks, and human health risks from trace metals on large regional scales like the Golden Triangle of Southern Fujian Province.

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

Assessment of metallic pollution status of surface water and aquatic macrophytes of earthen dams in Ilorin, north-central of Nigeria as indicators of environmental health

Studies of metal accumulation in fish are mainly focused on the muscle tissue, while the metal accumulation patterns in other tissues have been largely neglected. Muscle is not always a good indicator of the whole fish body contamination. Elemental accumulation in many fish tissues and organs and their potential use in monitoring programs have not received proper attention. In the present study, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn concentrations were assessed by inductively coupled plasma mass spectrometry (ICP-MS) in the following 14 tissues of the wels catfish (Silurus glanis) from the Danube River: muscle, gills, spleen, liver, kidneys, intestine, gizzard, heart, brain, gallbladder, swim bladder, vertebra, operculum, and gonads. A high level of differential elemental accumulation among the studied tissues was observed. The maximum overall metal accumulation was observed in the vertebra, followed by the kidneys and liver, with the metal pollution index (MPI) values of 0.26, 0.25, and 0.24, respectively. The minimum values were observed in the gallbladder, muscle, brain, and swim bladder, with MPI values of 0.03, 0.06, 0.07, and 0.09, respectively. Average metal concentrations in the fish muscle were below the maximum allowed concentrations for human consumption. The mean As, Cd, Pb, Cu, Fe, and Zn concentrations in the muscle were 0.028, 0.001, 0.001, 0.192, 3.966, and 3.969 μg/g wet weight, respectively. We believe that the presented findings could be of interest for the scientific community and freshwater ecosystem managers. There is a need for further research that would assess less studied tissues in different fish species.

Variation of trace metal minerals among different soil orders under different land use systems falling in Malwa region of Punjab in North-western India