Algoa Bay sediment metal distribution and potential ecological risk assessment

The aim of this study was to determine the concentration of Pb, Zn, Cu, Cd, Cr, and Fe in sediments of the Ichkeul Lake and rivers ecosystem in northern Tunisia; their comparison with international sediment quality criteria was also proposed to assess the extent of metal pollution and their origin using various pollution indicators. For this purpose, sediment samples were collected in thirteen locations and characterized for metal content (Pb, Cr, Zn, Cu, Cd, and Fe) using the total digestion technique. Pollution level was assessed via the geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (C ), potential ecological risk (PER), and pollution load index (PLI). Our results showed that all metals were lower than the threshold effect levels (TEL), the effect range low (ERL), the probable effect level (PEL), the effect range median (ERM), and the probable effect concentration (PEC) value, except Pb and Cr (higher than TEL), the threshold effect concentration (TEC), and the toxicity reference value (TRV). The geoaccumulation index (Igeo) indicated no pollution for Cr, Cu, Zn, and Fe, but moderate pollution for Pb. The enrichment factor showed no enrichment for most of the studied metals. This was further confirmed by the contamination factor that indicated low contamination levels, with the exception of Pb. The pollution load index (PLI) showed moderate pollution status in all the studied stations in the Ichkeul Lake and rivers ecosystem. The statistical results presented similar trends of Zn and Pb probably due to their similar pollution sources. It was found that the Ichkeul Lake and river ecosystems are characterized by moderate pollution status in all the studied sites except for that of a feeder river drained from an old lead mine which had relatively high metallic concentrations of Pb and Cd. It can be argued that effective remediation strategies and environmental management plans are required to control and reduce the input of environmentally hazardous toxic pollutants (Cd and Pb). This study may serve as a useful reference tool pertinent to approaches to the remediation of the old lead mine area surrounding the Ichkeul Lake as well as other areas under similar ecological conditions..

Contamination and risk assessment of trace metals and As in surface sediments from abandoned gold mining sites of Bekao, Adamawa-Cameroon

The research was conducted to determine the cause, dispersal, and risk assessment of metal-contaminated sediment. The sediment was collected from the Madna stream. It was transported to the laboratory, air-dried, ground with a mortar and pestle, and sieved. The sediment was digested with 10 ml of HNO3 and 30 ml of HCl and heated on a hot plate at 100 °C for about 2 hours. The 1 ml solution was diluted to about 50 ml and centrifuged at 1600 revolutions per minute for 10 minutes. The clear solution was analyzed by an atomic absorption spectrophotometer (AAS). The distribution of the average concentration showed that Cd < Cu < Co < Pb < Ni < Fe with a range of 0.03–72.81 mg/kg. The minimum Fe content was 99.78% higher than the maximum Ni, with Ni values being higher than other metals. The geoaccumulation index (igeo), the contamination factor (CF), and the pollution load index (PLI) showed insignificant contamination of the stream by the metals. However, the enrichment factor (EF) revealed minor to extreme enrichment for individual metals across the stations. However, The Ecological risk index (ERI) and Potential ecological risk (PER) showed low risk from individual and collective metals on the biota of the Madna stream ecosystem. There was no noncarcinogenic risk from the detected metals as the hazard quotient (HQ) and hazard index (HI) were <1; however, the children may suffer carcinogenic risk (CR) from cadmium through the nondietary oral route as Cadmium CR > 10−6. The sediment was assessed to be of high quality and posed no risk to the ecosystem as the average concentrations were lower than the effect range low (ERL), effect range median (ERM), and toxicology reference value (TRV). Based on the multivariate statistics and supported by EF, the sources of pollutants were anthropogenic and natural.

This study examined the spatio-temporality of heavy metal concentrations (Al, Cd, Co, Cr, Fe, Mn, Ni, Pb and Zn) in the sediments of Lake Bafa, one of the most important wetlands of Turkey’s Aegean region. The study evaluated sediment quality according to threshold effect concentration (TEC) and probable effect concentration (PEC) values based on sediment quality guidelines (SQG), and provided a potential ecological risk assessment (PERI) along with indices such as geoaccumulation index (NIgeo), enrichment factor (EF), contamination factor (CF), and pollution load index (PLI). For this purpose, surface sediment from 10 different points and core samples from three different points were seasonally collected and the concentrations of nine heavy metals were determined by ICP-MS. The findings indicated the following accumulation order of heavy metals in the sediment: Fe &gt; Al &gt; Mn &gt; Ni &gt; Cr &gt; Zn &gt; Pb &gt; Co &gt; Cd, with concentrations of Al, Mn, and Ni being high in the surface sediment samples. According to the NIgeo, surface sediment and core samples were very slightly polluted with Cr, Mn, and Co at most stations, while five stations were slightly polluted with Cd. Regarding EF, the lake was at risk in terms of Al and Pb accumulation. The CF results indicated that the lake was under pressure in terms of heavy metal pollution. The PLI results indicated a significant pollution hazard at all stations, while the PERI analysis indicated moderate risk of heavy metal pollution at some stations. As one of the most comprehensive studies applying such indices to Lake Bafa, the results are very significant in terms of evaluating the lake’s ecological sustainability.

Spatial and seasonal assessment of heavy metal contamination in Golden Horn sediments, İstanbul, Türkiye: Ecological impacts, human health risks, and environmental monitoring.

Assessing spatial patterns and ecological risks to coastal ecotourism: A case study from the Bohai Sea.

This study presents the first comprehensive assessment of heavy metal contamination, ecological risk, and potential human health implications in alluvial sediments from the Mbam and Noun Rivers in Central Cameroon. Eighty-two sediment samples were collected and analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) to determine the concentrations of Cr, V, Ni, Cu, Zn, Pb, Sn, U, and Th. The results were compared with upper continental crust (UCC) background values and ecotoxicological benchmarks, including threshold effect level (TEL), probable effect level (PEL), effect range-low (ERL), and effect range-median (ERM). Several contamination and ecological indices are as follows: contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo), pollution load index (PLI), and ecological risk indices (Er, RI) were used to evaluate pollution intensity and its environmental implications. In the Mbam River, metal concentrations generally decreased upstream, following the order V > Cr > Zn > Ni > Cu > Pb > Th > Sn > U, with moderate contamination (CF = 1.2-3.5) and PLI values between 1.3 and 1.5, indicating diffuse anthropogenic influence. In contrast, the Noun River displayed extremely high uranium and vanadium enrichment (CF₍U₎ > 5; EF₍U₎≈3.8), resulting in RI values up to 240, which denote considerable to very high ecological risk. Human health indices revealed hazard index (HI) values below 1 for all sites, indicating no immediate non-carcinogenic risk, though children showed higher exposure (HI_child = 0.19-0.34) than adults. Total carcinogenic risk (TCR) values (10-⁶-10-4) remained within the acceptable range but were highest at downstream Mbam sites, reflecting cumulative exposure to Cr (VI), Ni, and U. These findings indicate that metal enrichment in both rivers stems from the weathering of uranium-bearing lithologies combined with localized anthropogenic activities, including artisanal mining and agricultural runoff. Continuous monitoring and integrated watershed management are recommended to mitigate ecological degradation and long-term health risks in the Mbam-Noun River system.

The impact of seasonal waterlogging on the depth-wise distribution of major and trace metals in the soils of the eastern Ganges basin

Occurrence, distribution, and ecological risk of heavy metals and persistent organic pollutants (OCPs, PCBs, and PAHs) in surface sediments of the Ashtamudi wetland, south-west coast of India

Metal contamination along the French Mediterranean coast: From background to current status.

In the present study, heavy metals concentration and physico‐chemical properties of surface sediments of River Soan, Pakistan, have been investigated. In order to gain insight into the metals distribution, accumulation, and their pollution status, geo‐accumulation index (Igeo) and enrichment factor (EF) were used. The ecological risk for different heavy metals was evaluated using sediment quality guidelines, threshold effect concentration (TEC), and probable effect concentration (PEC). The concentration of heavy metals was relatively high in the post monsoon season as compared to the pre monsoon season. The concentration of Cd was 69% in sediment samples that exceeded the TEC value while none of the metal concentration exceeded PEC. The mean PEC quotient value among different sampling sites ranged between 0.14 and 0.43. The Igeo indicated that surface sediments of River Soan were moderately polluted with Cd (1.42). The EF indicated significant pollution of Cd (12.01) and moderate pollution of Pb (4.05) in sediments, and indicated the influx of Cd and Pb in sediments from anthropogenic sources. Multivariate results indicated an effective role of organic matter, sediment pH, weathering of rocks, and particle size in distribution of metals along with identification of natural and anthropogenic sources of metals. The results can be used for effective management of fresh water resources in Pakistan as well as these findings are applicable to the other rivers of Himalayan region.

Trace metal geochemistry sediments from the Dibamba River, SW Cameroon: Implication for heavy metal assessment and origin

In this study, the concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in the sediments of Nwaenebo River in Enugu, Nigeria, that received petroleum depot effluents for over twenty years were determined and the associated extent of pollution, ecological and human health risks of exposure estimated. The concentration of the PAHs was measured using gas chromatography. Extent of sediment PAHs pollution was determined using Nemerow pollution index whereas ecological risks were determined mainly by means of hazard quotient (HQ) based on Canadian interim freshwater sediment quality guidelines (ISQGs), probable effect concentration (PEC) and effect range medium (ERM) values. The non-carcinogenic and carcinogenic risks were determined using hazard index (HI) and incremental life cancer risks (ILCR) respectively. Results showed ƩPAH concentration range of 0.5–154.5 mg/kg in the sediments with 5-member ring PAHs most abundant in the downstream section of the river. The Nemerow pollution index showed that the sediments of the downstream section of the river were seriously polluted with the PAHs unlike the upstream section where there was no significant sediment PAHs pollution indicating that the petroleum depot was responsible for the pollution of the sediments with PAHs. The ISQG, PEC and ERM based HQ indicate insignificant risks to biota at upstream section but significant risks at the locations downstream where there are expectations of observable frequent adverse effects to the biota. There are no significant non-carcinogenic risks to human health but there are significant carcinogenic risks with risks at the downstream section of the river sediments in the range 9.4*10^-5 to 2*10^-4. Remediation efforts should be initiated to restore the sediments quality.

Pollution indices and ecological risk assessment of major elements and trace metals in the marine sediment of the western Nigeria continental shelf, Gulf of Guinea

Spatial distribution, environmental risk and sources of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in surface sediments-northwest of Persian Gulf