Metal Concentrations In Sediment Samples Research Articles

A Microcosm Analysis of Species-Specific Responses of Chironomidae on Heavy Metal Pollution in The Nyanza Gulf of Lake Victoria

The Chironomidae family, known as "non-biting midges" in their adult stage and "bloodworms" in their larval stage, consists of diverse dipteran insects inhabiting various global aquatic environments. Despite extensive global research, data on Chironomidae in the polluted Nyanza Gulf of Lake Victoria, Kenya, is scarce, and molecular identification methods have not been explored. This study aimed to quantify heavy metal concentrations in water, sediment, and insect samples and assess their impact on Chironomid species identified using mitochondrial DNA barcoding of the cytochrome oxidase subunit 1 (COI) gene. Analysis of Variance was used to determine if there were any statistically significant differences in heavy metal concentrations across different sample types or locations along the pollution gradient. Chironomids were collected from Nyanza Gulf, focusing on a pollution gradient. Results showed that concentrations of arsenic (As), lead (Pb), and cadmium (Cd) in insect, water, and sediment samples exceeded standard limits, while mercury (Hg) concentrations were within limits. Significant variations (p ≤ 0.05) in Pb levels were observed in water samples, and heavy metal concentrations in sediment samples varied significantly (p ≤ 0.05), with Pb showing the highest variation (p ≤ 0.0001). Insect samples exhibited significant differences (p ≤ 0.0001) in As and Hg contents. Genetic analysis identified two known species: Chironomus transvaalensis at the heavily polluted Kisumu station and Chironomus pseudothummi at the moderately polluted Kendu Bay and Homa Bay stations. Additionally, a unique Chironomus species was found on Ndere Island, a relatively clean site with restricted human activities. Sequence comparisons indicated proximity to global data but also highlighted the evolutionary significance and uniqueness of the identified species. This study demonstrated the potential use of genetic methods in determining Chironomid species diversity, community structure, and abundance in relation to heavy metal concentration. It suggests that heavy metal pollution may act as a selective pressure, driving the evolution of Chironomid species. The study recommends combining genetic approaches with other pollution sources for a comprehensive understanding of using this species in monitoring pollution

Seasonal variability in trace metal concentrations in sediment samples from the Puducherry and Cuddalore coasts of Tamil Nadu, India

The Puducherry-Cuddalore coastal region was chosen for research because these two cities receive the majority of their anthropogenic inputs from the Ponnaiyar and Gadilam rivers, which supply domestic, industrial, fishing port, and agricultural inputs. In southern Tamil Nadu, the Ponnaiyar and Gadilam rivers, as well as other minor rivers, combine and discharge into the southeastern Indian Ocean. Some studies have been carried out to investigate the impact of anthropogenic, industrial, and other influences on surface sediment samples along Tamil Nadu's south-east coast, from Puducherry to Cuddalore. A detailed assessment of these findings is explained in this research. Geochemistry and geology, as well as alterations in sediments, have all been widely researched. Heavy metals were absorbed by alluvial sands, silts, clays, and organic matter, which is also an indication of pollution in the environment. As a result, the metal content in pre-monsoon sediments is lower in Puducherry coastal areas than in Cuddalore coastal areas. Because of a rise in clay composition, higher trace metals were detected in post-monsoon sediments than in pre-monsoon sediments. Contamination levels in Puducherry and Cuddalore coastal areas were moderate to high in post-monsoon than pre-monsoon periods, with the exception of Cr, which significantly above the range of widespread pollution in post-monsoon periods. Sediments sampled from Puducherry and Cuddalore offshore were found to have moderate to considerable contamination. With the notable exception of lead, most elements of trace metal levels in sediments indicate relatively low levels of pollution. Among the consequences discussed in the report's findings are alterations in post-monsoon hydrodynamic processes and environmental health of the marine ecosystem.

Trend analysis of anthropogenic activities affecting trace metals deposition in core sediments from the coastal and four rivers estuary of Sarawak, Malaysia.

This study reports the concentrations of trace metals in core sediments profile from the coastal and four rivers estuary in the Kuching Division of Sarawak, Malaysia, and the controlling mechanisms influencing their availability in sediments of the studied area. The bonding of trace metals with non-mobile fractions was confirmed with the sequential extraction. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to measure the concentrations of the trace metals. Granulometric analyses were performed using normalized sieve apertures to determine the textural characteristics of the sediments. Enrichment factor was used to evaluate the level of metal enrichment. Heavy metals concentrations in sediment samples varied in the range: Pb (8.9-188.9mg/kg d.w.), Zn (19.4-431.8mg/kg d.w.), Cd (0.014-0.061mg/kg d.w.), Ni (6.6-33.4mg/kg d.w.), Mn (2.4-16.8mg/kg d.w.), Cu (9.4-133.3mg/kg d.w.), Ba (1.3-9.9mg/kg d.w.), As (0.4-7.9mg/kg d.w.), Co (0.9-5.1mg/kg d.w.), Cr (1.4-7.8mg/kg d.w.), Mg (68.8-499.3mg/kg d.w.), Ca (11.3-64.9mg/kg d.w.), Al (24.7-141.7mg/kg d.w.), Na (8.8-29.4mg/kg d.w.), and Fe (12,011-35,124.6mg/kg d.w.). The estimated results of the enrichment factor suggested enrichments of Pb, Zn, and Cu in all the core sediment samples and depths at all sites. The other trace metals showed no enrichments in almost all the sampled stations. Continuous accumulation of Pb, Zn, and Cu metals over a period can be detrimental to living organisms and the ecology. The results obtained from the statistical analyses suggested that the deposition of trace metals in the studied sites is due to anthropogenic inputs from the adjacent land-based sources.

Ecological health of coral reefs in Zanzibar

Coral reefs are important ecosystems in terms of their biodiversity and ecosystem functions. Particularly at local scales, coral reefs are vulnerable to natural and anthropogenic disturbances, leading to the degradation of reef health. Here, we employed two different methods to monitor reef health. First, we conducted line transect surveys to record the benthic community structure to infer ecological reef health. Secondly, trace metal concentrations in sediment samples and a bioindicator sponge species, Haliclona fascigera, were compared among sites to detect cryptic degradation and unknown sources of pollution. The study area comprised six reefs situated along the coast of Zanzibar’s main agglomeration, Stone Town, and subject to different types of disturbances and conservation management schemes. Overall, coral reef health was found to decrease with increasing proximity to Stone Town, with living hard coral cover being particularly low on reefs closest to Stone Town, which coincided with greater fishing, tourism, and pollution pressures. Reef assessments based on trace metal analyses differed from the community structure surveys. All sites showed high levels of arsenic and cadmium contamination, with some samples revealing concerning levels of chromium, copper and zinc. The reefs differed significantly between each other in terms of trace metal concentration for both sediments (p= 0.031, PERMANOVA) and sponge samples (p= 0.001, PERMANOVA). Trace metal concentrations were not correlated with distance to Stone Town, highlighting the downstream effects of industrial and urban sewage on even remote reefs. Coral reef health assessment was found to be dependent on the survey method employed, which is why we recommend the combination of complementary methods.

Analysis And Pollution Assessment of Some Trace Heavy Metals in Freshwater, Drinking Water, Fish, and Sediments Samples in Suez Canal Region, Egypt by Flame Atomic Absorption Spectrometer

Monitoring of pollution levels of heavy metals in freshwater is significant to human health and environmental management. The objective of the current study was to monitor the freshwater quality in Suez Canal region, Egypt and to determine the efficacy of water treatment system in the removal of contaminates like heavy metals residues. The concentrations of some heavy metals (As, Cd, Cr, Pb, Hg, Ni, Cu, Mn) were determined in freshwater, treated water, in muscle of fish species (Tilapia nilotica) and sediment. The results of the study revealed that , all heavy metals concentrations in freshwater and treated water were within the permissible limits except, Lead concentration in treated water was higher than the permissible limits. In Port Said, all metals concentrations in both freshwater and treated water samples were within the permissible limits. Fish samples collected from the three governorates showed an increase in Cd and Pb levels. The heavy metals concentrations in sediment samples were remarkably high.

Geochemical characterisation of stream sediments and soil samples from Karewa deposits of south Kashmir, NW Himalaya, India

Thirty-six sediment samples from twelve soil profiles have been collected from Karewa deposits of south Kashmir with an objective for evaluating weathering of the source area, palaeoclimate and environmental contamination. Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA) and Chemical Index of Weathering (CIW) values of the sediments averaged at 53.99, 68.6 and 72.53 indicating low to moderate degree of weathering. Higher values are observed in the samples collected at top surface. The samples taken at 15 cm depth and 60 cm depth showed almost similar but lesser values than top soil samples. A–CN–K and A–CNK–FM diagrams showed an almost similar contents for Al2O3, CaO, Na2O, K2O and MgO as those of upper crust, reflecting very poor to moderate weathering history. The ratio plots of SiO2 vs Al2O3 + K2O + Na2O and CIA (molar) vs Al2O3 indicate semi-arid climatic conditions with a mean annual precipitation of 846 mm per year and mean annual paleo-temperature of 10.91 °C. Metal concentration in sediment samples ranged from 331.1 to 571 ppm (Ba), 146 to 292 ppm (Zr), 82 to 587 ppm (Sr), 70 to 130 ppm (Cr), 58.9 to 120 ppm (Rb), 37.6 to 112 ppm (V) and 43 to 112 ppm (Zn). The enrichment ratio of 6 for As, 3 for Cr and 2 for Ni, Sb and Tb indicate the enrichment of these metals in the sediment samples. The QoC plot of As, Ni, Co and Cr illustrated an anthropogenic source and Ba, Rb, Sr, Nb, and Ta were mainly derived from geogenic sources with no evidence of anthropogenic contamination.

Copper, zinc, manganese, cadmium and chromium in crabs from the mangrove wetlands in Qi'ao Island, South China: Levels, bioaccumulation and dietary exposure

Abstract Mangrove wetlands are under increasing pollution pressure from human activities due to rapid industrialization and urbanization of coastal regions. Many pollutants such as heavy metals may be accumulated via food chains to hazardous levels which will thus bring potential health issues to humans. In the present study, three species of crabs (Sesarma dehaani, Sesarma plicata, Macrophthalmus japonicus) and associated sediments from three mangrove habitats with different vegetation were collected from the mangrove wetlands in Qi'ao Island, South China to investigate the levels, bioaccumulation and dietary exposure of heavy metals including copper (Cu), zinc (Zn), manganese (Mn), cadmium (Cd) and chromium (Cr). Metal concentrations in sediment samples were 65–91, 212–247, 506–1256, 0.6–1.3, and 8.8–14 mg/kg dry weight for Cu, Zn, Mn, Cd and Cr, respectively. The spatial heterogeneity of these metals in mangrove sediments was observed with a descendant order of metal concentrations as Mn > Zn > Cu > Cr > Cd at each site. Species-specific and tissue-specific accumulation of metals was also found in mangrove crabs, both in the degree of accumulation of particulate metals and the tissues in which they were most abundant. All biota-sediment accumulation factors (BSAF) values >1 for Cd in each crab species suggested that the native mangrove crabs tended to be good tools for the monitoring of Cd pollution in mangrove forests. Results of the estimated daily intake (EDI) and target hazard quotient (THQ) suggested that consumption of the mangrove crabs in Qi'ao Island might subject local residents to potential health risks as far as the metals are concerned.

Heavy metal contamination in sediments from vehicle washing: a case study of Olarong Chhu Stream and Paa Chhu River, Bhutan

ABSTRACTHeavy metal contamination owing to anthropogenic activities affects human health and is of worldwide concern. The aim of the study was to investigate the possible linkage between vehicle washing and heavy metal contamination. Heavy metal concentration in sediment samples from vehicle wash wastewater settlement tanks (WSTs) and water bodies (Olarong Chhu and Paa Chhu) used for discharging untreated wastewater was determined with an atomic absorption spectrophotometer. High concentrations of Cd, Cr, Cu, Fe, Pb, Ni and Zn were found in WSTs. Assessment of sediment pollution in water bodies was determined using contamination factor (CF), pollution load index (PLI), geo-accumulation index (Igeo) and enrichment factor (EF); these indices denoted anthropogenic inputs of heavy metals. Significant Pearson correlations between heavy metals in sediments from Olarong Chhu, Paa Chhu and WSTs indicated their common origin. Thus, this study confirms the linkage between vehicle washing and heavy metal contamination. Bhutan’s policy on installation of wastewater treatment plants should be implemented effectively. Bhutan should consider feasible methods for the safe disposal of sludge from WSTs.Abbreviations: Atomic Absorption Spectrophotometry - (AAS)

Radon emanation and heavy-metals assessment of historical warm and cold springs in Nigeria using different matrices

BackgroundIn recent years, attention has been drawn to radon gas as main risk factor for lung cancer. Radon is colourless, odourless and tasteless radioactive noble gas. To mitigate radon effects, water consume by populace needs to be conserved. Radon concentration in water and heavy metals concentrations in sediment samples from historical cold and warm springs at Ikogosi were determined using Durridge RAD-7 analyzer with RAD H2O accessory and atomic absorption spectrophotometer.ResultsThe mean activity concentration of radon in water samples ranged from 0.07 to 0.36 with overall mean value 0.20 Bq L−1, 35–210 with an overall mean value 75.9 Bq L−1 and 11.7–140.0 with an overall mean 79.4 Bq L−1 for bottled, cold and warm water samples respectively. The calculated total effective dose values were below 100 µSv year−1 recommended by WHO. The result of elemental analysis showed that the mean values of metals concentrations were Pb (2.9–11.8 mg kg−1), Cu (3.8–12.8 mg kg−1), Fe (945.0–2010.0 mg kg−1), Cd (0.6–1.7 mg kg−1) and Ni (0.3–2.6 mg kg−1).ConclusionsThe results revealed values not higher than recommended permissible limit and background values. The pollution load index, revealed that the overall contamination of metals indicated no significant pollution in all the studied samples.

Assessment of Heavy Metals Contamination in Sediments of the Vridi Canal (Côte d’Ivoire)

The concentrations of cadmium, copper, lead and zinc in sediment samples from the Vridi Canal (Harbour area of economic capital of Cote d’Ivoire) were determined to evaluate the level of contamination. All metal concentrations in sediment samples, except Cu, were greater than the concentration of Upper Continental Crust (UCC). Sediment pollution assessment was undertaken by using Enrichment Factor (EF), geoaccumulation index (Igeo) and Pollution Load Index (PLI). The enrichment factor (Cd: EF = 20.04; Pb: EF = 3.43; Zn: EF = 1.56) and geoaccumulation index (Cd: Igeo = 4.29; Pb: Igeo = 1.81) showed that the sediments were polluted. The Pollution Load Index (PLI > 1) indicated that the sediments of the studied area were heavily contaminated. Based on the comparison with sediment quality guidelines, the concentrations of cadmium, lead and zinc would be toxic to one or more species of aquatic organisms living in the sediments.

Evaluation of total trace metal (TTMs) enrichment from estuarine sediments of Uppanar, southeast coast of India

The present study was carried out to investigate the impact of anthropogenic influences on Uppanar estuary situated at Cuddalore with regard to trace metal concentration in sediment samples of the study area. The Uppanar River runs similar to the coast south of Cuddalore town and a number of small streams of domestic, treated and unprocessed effluents from industries join the coast through the river. Average concentration of Cr, Cu and Ni (106, 87 and 137.1 ppm) is above the continental value indicating that increase in the concentration may be due to metal industries, and surface runoff of the fertilizer remains increases the concentration of the metal in the sediments. There is moderate level of pollution related to anthropogenic activities. The trace metals showed association with Fe and Mn indicating their adsorption on Fe–Mn oxyhydroxides. Correlation coefficient between pairs of metals concentration show that all metals and organic carbon significantly correlate with trace metal except sand and calcium carbonate. Geoaccumulation index and enrichment factors, the sediment is classified as unpolluted to moderately polluted with Fe, and Cu and moderate to considerable with Pb and Co. From the study, it can be revealed the anthropogenic activities are the prime source for the biodegradable toxic metal in the sediment of Uppanar estuary in the Cuddalore coastal zone.

Coupling between the Changes in CO<sub>2</sub> Concentration and Sediment Biogeochemistry in Mudflat of Salinas de San Pedro, California, USA

We investigated the effects of elevated carbon dioxide (CO2) on biogeochemistry of marsh sediment including speciation of selected heavy metals in Salinas de San Pedro mudflat in California. The Salinas de San Pedro mudflat has higher carbon (C) content than the vast majority of fully-vegetated salt marshes even with the higher tidal action in the mudflat. Sources for CO2 were identified as atmospheric CO2 as well as due to local fault degassing process. We measured carbon dioxide, methane, total organic carbon, dissolved oxygen, salinity, and heavy metal concentration in various salt marsh locations. Overall, our results showed that CO2 concentration ranging from 418.7 to 436.9 (ppm), which are slightly different in various chambers but are in good agreement with some heavy metal concentrations values in mudflat at or around the same location. The selected metal concentration values (ppm) ranging from 0.003 - 0.011 (As); 0.001 - 0.005 (Cd); 0.04 - 0.02 (Cr); 0.13 - 0.38 (Cu); 0.11 - 0.38 (Pb); 0.0009 - 0.020 (Se); and 0.188 - 0.321 (Zn). The low dissolved oxygen (ppm) in the pore water sediment indicated suboxic environment. Additionally, CO2 (ppm) and loss on ignition (LOI) (%) correlated inversely; the higher CO2 content, the lower was the LOI (%); that is to say the excess CO2 causes higher rates of decomposition and therefore it leads to lower LOI (%) on the mudflat surface. It appears that the elevated CO2 makes changes in salt marsh pore water chemistry for instance the free ionic metal (Cu 2+ , Pb 2+ , etc.) speciation is one of the most reactive form because simply assimilated by the non-decayed or alive organisms in sediment of salt marsh and/or in water. This means that CO2 not only is a sign of improvement in plant productivity, but also activates microbial decomposition through increases in dissolved organic carbon availability. CO2 also increases acidification processes such as anaerobic degradation of microorganism and oxidation of reduced components. The heavy metal concentrations in sediment samples were slightly higher in suboxic layer, yet it appears that salt marsh sediments in Salinas de San Pedro act like a sink for nutrient and carbon by maximizing carbon sequestration.

Trace metal and radionuclide pollution in marine sediments of the Aegean Sea (Izmir Bay and Didim)

To determine radioactivity and trace metal levels, surface sediments were collected from two important areas (Izmir Bay and Didim) in the Aegean Sea region of Turkey, and were analyzed for concentrations of 210Po, 210Pb and trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn). The average 210Po and 210Pb massic activities in sediments varied in the range of 24 ± 5 to 126 ± 6 Bq kg−1 dry wt. and 18 ± 3 to 59 ± 4 Bq kg−1 dry wt., respectively. Izmir Bay exhibited the highest polonium activities in sediments, likely due to specific sedimentation processes and other sediment characteristics. The trace metal results showed that the Izmir Bay is facing trace metal pollution. The metal concentrations in sediment samples are low compared to those from the other neighboring marine environments.

Distributation and Implications of Heavy Metal in Jiangsu Coastal Sediments in China

Heavy metal concentrations in sediment samples from the Jiangsu coast were determined to explore the spatial distribution and the levels of contamination. The total Cu concentration in the wet season showed higher values than those of the dry season for all stations in Lianyungang coast. The highest CF values for Zn, Cr and Ni at S2, which receives a huge amount of metallic discharge from Zn and Cr mine in bulk in port of Lianyungang. Cu, Cr, Cd, Pb and Ni had the highest EF values at Yancheng coast and Cd had the highest EF values in Nantong region. The Pb and Ni concentration levels are mainly affected by natural sources in Nantong coast and the potential ecological risk indices of Cu and Cd in Yancheng coast, which indicated moderate potential ecological risk of two metals. And the risk associated with Cr in the sediment was moderate risk in most coasts, while the concentrations of Pb in most coasts were of higher risk. The heavy metal concentration of Cu, Zn, Cr and Pb at Lianyungang, Zn, Cr and Pb at Yancheng, Cu, Zn Cr, Pb and Ni at Nantong were below ERL, which represent a minimal-effects range, which is intended to estimate conditions where biological effects are rarely observed. For Cd concentrations at Lianyungang, Yancheng and Nantong are greater than ERL and more than ERM, which represents a range with in which represents the potential acute toxicity of contaminants and aprobable effect range within which adverse biological effects frequently occur. For Pb and Ni contaminant at Yancheng are greater than ERL and less than ERM, which represents a range with in which biological effects occur occasionally.

Assessment of nutrient and heavy metal contamination in surface water and sediments of the upper Tigris River, Turkey

Abstract The concentrations of total nitrogen (TN), total phosphorus (TP), As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in both surface water and sediment samples from the upper Tigris River were determined to evaluate the level of contamination. All metal concentrations in water samples, except Cu, were lower than the maximum permitted concentration for the protection of aquatic life. TN, TP and metal concentrations in sediment samples from the first three sites situated downstream of Ergani Copper Mine Plant were much higher than those at other sites. There was a significant decrease in the concentrations of heavy metals in sediment from the last site downstream of the Dicle Dam. Sediment pollution assessment was undertaken using enrichment factor (EF) and geoaccumulation index ( I geo ). The sediments of sites downstream of the copper mine plant showed significant enrichment with Cd, Co, Cu, Pb and Zn, indicating metallic discharges from the Ergani Copper Mine Plant. The I geo values revealed that Cu (5.09), Co (4.26) and Zn (3.18) were significantly accumulated in the study area. Based on the comparison with sediment quality guidelines, the concentrations of Cr, Cu, Ni, Pb and Zn at sites downstream of the copper mine plant are likely to result in harmful effects on sediment-dwelling organisms. Cluster analysis suggests that As, Cd, Co, Cu, Ni, Pb and Zn are derived from anthropogenic sources, particularly metallic discharges of the copper mine plant.

Assessment of heavy metal contamination in sediments of the Tigris River (Turkey) using pollution indices and multivariate statistical techniques

Heavy metal concentrations in sediment samples from the Tigris River were determined to evaluate the level of contamination. The highest concentrations of metals were found at the first site due to metallic wastewater discharges from copper mine plant. Sediment pollution assessment was carried out using contamination factor (CF), pollution load index (PLI), geoaccumulation index ( Igeo) and enrichment factor (EF). The CF values for Co, Cu and Zn were >6 in sediments of the first site, which denotes a very high contamination by these metals. The PLIs indicated that all sites except the first site were moderately polluted. Cu, Co, Zn and Pb had the highest Igeo values, respectively. The mean EF values for all metals studied except Cr and Mn were >1.5 in the sediments of the Tigris River, suggesting anthropogenic impact on the metal levels in the river. The concentrations of Cr, Cu, Ni and Pb are likely to result in harmful effects on sediment-dwelling organisms which are expected to occur frequently based on the comparison with sediment quality guidelines. PCA/FA and cluster analysis suggest that As, Cd, Co, Cr, Cu, Mn, Ni and Zn are derived from the anthropogenic sources, particularly metallic discharges of the copper mine plant.

Non-residual heavy metals in Lake Nasser bed sediments, Egypt.

he Present study with the determination of concentrations of non-residual heavy metals (Iron, Manganese, Lead, Cadmium, Chromium, Copper, Nickel and Zinc) in Lake Nasser bed sediments as compared with total heavy metals contents in order to identify their environmental risk in Lake water. The analysis involves testing of sediments collected from eight sampling sites along riverine and transtion zones of Lake Nasser. Organic matter content for each of the sediment samples was also reported to study the effect of its content on the accumulation of metals in bed sediments. It was found that, the non-residual heavy metal levels (mg kg -1 ) in bed sediments were 0.11±0.05, 13.28±5.02, 12.52±2.89, 25.54±11.1, 24.53±11.29, 27.66±7.29, 11610±2810 and 418.87 ± 190.91 for Cd, Cr, Pb, Ni, Cu, Zn, Fe and Mn respectively. It represents about 20.4, 19.9, 25.2, 38.6, 57.6, 49.3, 41.1 and 45.8% from the total content of these metals respectively. Fe-Mn oxides and organic matter seem to be the main carrier phases for the non-residual fraction of these metals. The order of non-residual metal concentrations in sediment samples was found to be Fe>Mn>Zn, Ni>Cu>Cr>Pb>Cd. In the present study, sediment quality assessment was done by calculating sediment pollution index and metal pollution index. The results of the assessment showed that, stream sediments from Lake Nasser are categorized into SPI0 natural sediments in all sites, except one site at km 403 which show SPI1 low polluted sediment. Metal pollution index highlights concentration differences between sites. Moreover, by comparing the results with sediment quality guidelines, it can be found that the Cd, Cu, Zn, Pb and Cr levels belong to the concentration below The Effect Range Low (ERL) and the toxicity to the biota in Lake Nasser was rarely occurred. It was also observed that, non-residual heavy metals were found very low compared with the agricultural land use target. This indicates that, Lake Nasser sediment can be used in amendment of agricultural land. The results of this study recommended the use of a pilot project to evaluate the characteristics of sediment for its potential use in agricultural land and to identify how sediments affect the crop yields. Some statistical applications were applied to study the behavior of the metal contents and their correlations in bed sediments.

Non-residual heavy metals in Nasser lake bed sediments

on-residual metal in bed sediments is the amount of metal that is not present in the silicate matrix. It includes metal adsorbed on sediment particles, complexed by and adsorbed on organic matter, and in the form of soluble salts. Metal toxicity is dependent on its chemical form, mobility, degree of transformation, and bioavailability, which allow metal contaminants to enter the food chain. Bioaccumulation of metals by biota in surface water and by plants and animals in terrestrial can adversely affect humans. This paper deals with the determination of concentrations of non-residual heavy metals (Iron, Manganese, Lead, Cadmium, Chromium, Copper, Nickel and Zinc) in Nasser Lake bed sediments as compared with total heavy metal content in order to identify their environmental risk in Lake Water. The analysis involves testing of sediments collected from eight sampling sites along riverine and transition zones of Nasser Lake. Organic matter content for each of the sediment samples is also reported to study the effect of its content on the accumulation of metals in bed sediments. It was found that, the non-residual heavy metal levels (mg kg -1 ) in bed sediments were 0.11±0.05, 13.28±5.02, 12.52±2.89, 25.54±11.1, 24.53±11.29, 27.66±7.29, 11610±2810 and 418.87±190.91 for Cd, Cr, Pb, Ni, Cu, Zn, Fe and Mn respectively. It represents about 20.4, 19.9, 25.2, 38.6, 57.6, 49.3, 41.1 and 45.8% from the total content of these metals respectively. Fe-Mn oxides and organic matter seem to be the main carrier phases for the non-residual fraction of these metals. The order of non-residual metal concentrations in sediment samples was found to be Fe>Mn>Zn, Ni>Cu>Cr>Pb>Cd. In the present study, sediment quality assessment was done by calculating sediment pollution index and metal pollution index. The results of the assessment showed that, stream sediments from Nasser Lake are categorized into SPI0 natural sediments in all sites except one site at km 403 which show SPI1 low polluted sediment. Metal pollution index highlights concentration differences between sites. Moreover, by comparing the results with sediment quality guidelines, it can be found that the Cd, Cu, Zn, Pb and Cr levels belong to the concentration below The Effect Range low (ERL) and the toxicity to the biota in Nasser Lake was rarely occurred. It was also observed that, nonresidual heavy metals were found very low compared with the agricultural land use target. This indicates that, Nasser Lake sediment can be used in amendment of agricultural land. The results of this study recommended the use of a pilot project to evaluate the characteristic of sediment for its potential use in agricultural land and to identify how sediments affect the crop yields. Finally, some statistical applications were applied to study the behavior of the metal contents and their correlations in bed sediments. N

Speciation of some heavy metals in River Nile sediments, Cairo, Egypt

River sediments are basic components of our environment. It also constitutes a major source of persistent bioaccumulative toxic chemicals which may pose threats to ecological and human health even after contaminants are no longer released from point and non-point sources. Therefore, the aim of this study was to investigate the mobility and the availability of metals in sediments from different sites along the Nile River in Cairo district using sequential chemical extraction technique. The speciation data showed that most metals were associated with organic/sulfide and residual fractions. The order of total metal concentrations in sediment samples was found to be Fe > Mn > Zn > Ni > Cu ≥ Cr > Pb > Cd.

A note on the concentrations and bioavailability of selected metals in sediments of Richards Bay Harbour, South Africa

Sediments are considered to be the ultimate sink for most contaminants and therefore pose the highest risk to these aquatic environments. This paper presents the levels of metals in sediments from Richards Bay Harbour, 20 years after the construction of the harbour and studied spatial and temporal, as well as the proportion of the bioavailable metal fraction. Sediment samples were collected from nine sites in Richards Bay Harbour. Sequential extractions of metals were carried out and samples were analysed for aluminium, chromium, copper, iron, manganese and zinc. Metal concentrations in sediment samples varied only slightly between seasons but showed significant spatial variation, which was significantly correlated to sediment particle size composition. Highest metal concentrations were found in sites with substrata dominated by fine mud. Manganese and Zn had more than 50% of this concentrated in the easily reducible fractions. Zinc concentrations were not elevated when compared to historic data. More than 70% of Cr was concentrated in the inert fractions nevertheless concentrations recorded at some sites were still above action levels when considering only the bioavailable fractions. Keywords : sediments, metals, bioavailability, sediment composition, Richards Bay Harbour Water SA Vol. 31(4) 2005: 589-596