Temporal distribution of dissolved trace metal in the coastal waters of Southwestern Bay of Bengal, India

Ecological risk assessment of metal pollution in the surface sediments of delta region, Egypt

The surface sediments from eleven sectors perpendicular to the Egyptian Mediterranean Sea coast, along the delta region, have been assessed. These sectors cover areas of Eastern Harbour, Abu Qir Bay, Rosetta, Abo Khashaba, Burullus, Baltim, Damietta, and Manzala. The assessment process is based on determining the eight metals' (Fe, Cu, Zn, Mn, Ni, Co, Pb, and Cd) content, followed by applying different pollution and ecological risk indices such as enrichment factor (EF), geoaccumulation factor (Igeo), contamination factor (CF), Pollution Load Index (PLI), degree of contamination (Cdeg.), Nemerow Integrated Pollution Index (NIPI), and Potential Ecological Risk Index (PERI). The results indicate the average concentrations of metals (μg/g) were Fe (18,000), Mn (213), Zn (120), Ni (26), Co (13), Cu (12), Pb (10), and Cd (2). The single-pollution indices reveal that most metals were depleted to metal levels, the sediments were moderately polluted with Cd and unpolluted with other metals, and the CF values confirmed that the sediments were highly polluted with Cd and low contaminated with the rest of the metals. According to the integrated pollution indices, the Eastern Harbour, Damietta, Manzalah, and Bardawil (eastern Inlet) are the most polluted sectors relative to the rest, subjected to various point sources of pollution. Drainage management system is recommended to enhance water conservation and improve fish stocks.

Impact of storage temperature and filtration method on dissolved trace metal concentrations in coastal water samples

Trace elements play a major role in biogeochemical cycles and oceanographic processes. To determine trace element concentrations, the dissolved and particulate phase are usually separated by filtration. However, the frequently used membrane filtration as well as sample storage can bias the dissolved elemental concentrations by adsorption or desorption/contamination. We present a comparison of two filtration methods for coastal and estuarine water samples (pressure filtration with Nuclepore™ polycarbonate filters, vacuum filtration with DigiFILTER™s) applied to aliquots of a large-volume coastal water sample that were stored at -18°C or 4°C for up to nine weeks. The filtrates were analyzed by seaFAST-ICP-MS for dissolved Cd, Ce, Co, Cu, Dy, Er, Eu, Fe, Ho, La, Mn, Mo, Nd, Pb, Pr, Sm, Tb, U, V, W, Y, and Zn. The filtration blanks of DigiFILTER™s (0.0006 ± 0.0010 ng L-1 for Ho to 110 ± 180 ng L-1 for Zn) were sufficiently low for quantification of all analyzed elements with good repeatability, enabling a fast and reliable filtration of large sample sets of coastal water. However, the findings also highlight the need to measure procedural blanks including the filtration instead of only the instrument blanks to validate results. Measured concentrations of both filtration methods did not differ significantly for Cd, Cu, Mo, U, V, W, Zn but for other investigated elements, the ratio between both methods was up to 1.8 for Ce and 4.1 for Fe. Within nine weeks of storage, the elemental concentrations decreased significantly, resulting in losses of 20% Mn in frozen samples and 63% Pb, 64% Co and 93% Mn in cooled samples. PRACTITIONER POINTS: Two fast and cheap filtration methods for coastal water samples were compared. Dissolved concentrations of 22 elements were measured by seaFAST-ICP-MS. The filtration method is important in addition to filter pore size. Filtration blanks need to be reported to maintain comparability between methods. Cool and frozen storage of water samples biases the dissolved metal concentration.

In vivo appraisal of oxidative stress response, cell ultrastructural aberration and accumulation in Juvenile Scylla serrata exposed to uranium

In vivo studies were performed to evaluate the organ specific tissue accumulation and cellular toxicity of uranium to mud crab Scylla serrata. The specimens were acclimated in natural seawater and the exposure to 50-250 μg/L uranium was investigated up to 60 days. The present study examined the effects of concentration and duration of uranium exposure in the tissue of S. serrata at cellular and subcellular level using scanning electron microscopy and bright field transmission electron microscopy in addition to histological analysis. The results indicated that accumulation of U in S. serrata was organ specific and followed the order gills > hepatopancreas > muscle. The response of key antioxidant enzyme activities such as SOD, GPx and CAT in different organs of crabs indicated oxidative stress due to U in the ambient medium and tissue. At 50 and 100 μg/L of U exposure, individuals were able to acclimate the oxidative stress and withstand the uranium exposure. This acclimation could not be sustained at higher concentrations (250 μg/L), affecting the production of CAT in the tissues. Cellular and subcellular changes were observed in the hemocytes with reduction in their number in consonance with the antioxidant enzymes. Histological aberrations like lamellar disruption of gill, necrosis of hepatopancreas, disruption and rupture of muscle bundles were observed at different concentrations and were severe at higher concentration (250 μg/L). Necrosis was observed in the electron micrographs of tissues shortly after 15 days of exposure. SEM micrograph clearly shows disrupted lamellae, folding of marginal canal and reduction of inter lamellar spaces in the gills of crab exposed to high concentration of uranium. Mitochondrial anomalies are reported for the first time in the present study in addition to the subcellular changes and vacuoles on exposure uranium in the cells of gill and hepatopancreas.

Prescribing sea water quality criteria for arsenic, cadmium and lead through species sensitivity distribution

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium (Cd) and lead (Pb) have not been developed for India. The aim of this study is to derive the SWQC for the metals based on Species Sensitivity Distribution (SSD). Eight species of sensitive marine organisms belonging to five phyla were assessed for their sensitivity to toxicity of As, Cd and Pb. Median effective concentrations (EC₅₀) and Median Lethal Concentrations (LC₅₀) were derived from the acute toxicity bio-assays. No Observed Effect Concentrations (NOEC), Lowest Observed Effect Concentrations (LOEC) and chronic values were derived from chronic toxicity bio-assays. Diatoms were more sensitive to As with 96 h EC₅₀ of 0.1 mg/l and copepods were more sensitive to Cd and Pb with 96 h EC₅₀ of 0.019 mg/l and 0.05 mg/l respectively. Estimated NOECs ranged from 4.87 to 21.55 µg/l of As, 1.0 to 120 µg/l of Cd and 5.67 to 91.67 µg/l of Pb. Similarly, chronic values (µg/l) were in the range of 6.71-26.1, 1.38-170, and 7.67-91.67 of As, Cd and Pb respectively. The Criterion Maximum Concentration (CMC), Criterion Continuous Concentration (CCC) and Predicted No Effect Concentration (PNEC) values were prescribed as SWQC. The CMC (µg/l) of 19, 1.7 and 17 for As, Cd, and Pb were derived respectively for acute exposure during accidental marine outfalls. The CCC (µg/l) for As was 4.6, 1.1 for Cd and 5.9 for Pb are recommended as SWQC for protection of 95% of marine organisms. PNEC (µg/l) of 3.8 for As, 0.92 for Cd and 4.3 for Pb are suggested for highly disturbed ecosystems, shell fishing and mariculture uses of water bodies. These values are recommended as a baseline for site specific water quality criteria for the coastal waters of the country.

Distribution and ecological- and health-risk assessment of heavy metals in the seawater of the southeast coast of India

The objective of the present study was to conduct an ecological and health risk assessment of heavy metals in the seawater of the southeast coast of India. The distribution profile of heavy metals in the surface seawater was Fe (79.60 ± 21.57 μg/L) > Zn (9.31 ± 1.33 μg/L) > Cu (5.19 ± 2.00 μg/L) > Ni (2.45 ± 0.76 μg/L) > Mn (1.20 ± 1.00 μg/L) > U (0.44 ± 0.23 μg/L) > Pb (0.36 ± 0.06 μg/L) > Cr (0.31 ± 0.57 μg/L) > Cd (0.11 ± 0.05 μg/L) > Co (0.07 ± 0.20 μg/L). Cu level for most of the samples exceeded the USEPA criteria for acute CMC (criterion maximum concentration) and chronic CCC (criterion continuous concentration). Other studied metals, Cd, Cr, Pb, and Ni, remained below the acute CMC and chronic CCC guidelines. The seawater pollution index (I_wp) of Cr, Ni, Zn, Cd, and Pb complied with the category-I seawater (<1, unpolluted). The ERI values (0.46-3.99) of the seawater of the studied coast mostly fell under the ecologically low risk category with respect to heavy metals. Dermal Hazard index values were orders of magnitude lower than one, indicating no potential health concern due to dermal exposure.

Environmental characterization of a semiarid hyper saline system based on dissolved trace metal-macronutrient synergy: A multivariate spatio-temporal approach

Trace metals and macronutrients play key roles in marine biogeochemical processes. Despite their higher availability, no reliable information is available on their ecological role in the hypersaline waters of NW Arabian Gulf. The present study identifies their synergistic effect on environmental characteristics and autotrophic biomass in the shallow coastal and offshore waters, off Kuwait on a seasonal basis. Surface water samples collected along four predefined transects were analyzed for physico-chemical and biological variables during summer (n=27) and winter (n=27) seasons. Multivariate analyses revealed clear spatial and seasonal trends, and identified the best suit of environmental variables responsible for the seasonal variability in phytoplankton biomass. Using statistically derived supply to demand ratios, carbon-trace metal stoichiometry, and bioavailability of trace metals, we propose possible growth regulating factors for phytoplankton on a seasonal basis in the NW Arabian Gulf, off Kuwait. This is the first report on trace metals from the entire Arabian Gulf, using clean techniques and multivariate statistical approach.

Toxicity of Nickel on the Selected Species of Marine Diatoms and Copepods

Toxicity values for nickel on marine diatoms and copepods were derived based on bioassay tests. The 96 h IC₅₀ of nickel on diatoms, Odontella mobiliensis and Coscinodiscus centralis were 0.31 ± 0.01 and 0.62 ± 0.02 mg/L and LC₅₀ values on copepods, Oithona similis and Acartia danae were 2.78 ± 0.14 and 2.34 ± 0.32 mg/L, respectively. The species mean chronic values of nickel were 0.016, 0.17, 0.57 and 0.42 mg/L for O. mobiliensis, C. centralis, O. similis and A. danae, respectively. A hazardous concentration was derived and evaluated using the species sensitivity distribution (SSD) method. SSD indicated that 13 µg Ni/L is the maximum allowable concentration for protection of 95% plankton species in coastal and marine ecosystem of India. Diatoms are more sensitive to nickel than copepods by almost an order of magnitude. The toxicity values derived in the present study may be useful to calculate ambient water quality criteria/standard for nickel.

Spatial distribution, ecological and health risk assessment of heavy metals in marine surface sediments and coastal seawaters of fringing coral reefs of the Persian Gulf, Iran

Concentrations of 13 heavy metals (Al, Fe, Mn, Zn, Cu, Cr, Co, Ni, V, As, Cd, Hg, Pb) in 360 reef surface sediments (0-5 cm) and coastal seawater samples from ten coral Islands in the Persian Gulf were analyzed to determine their spatial distribution and potential ecological risks. Different sediment quality indices were applied to assess the surface sediment quality. The mean concentrations of metals in studied sediments followed the order: Al > Fe > Ni > V > Mn > Zn > Cu > Cr > Co > As > Cd > Pb > As. Average Cd and Hg exceeded coastal background levels at most sampling sites. With the exception of As, concentrations of heavy metals decreased progressively from the west to the east of the Persian Gulf. Based on the Enrichment Factor (EF) and Potential Ecological Risk Index (RI), concentrations of V, Ni, Hg and Cd indicated moderate contamination and is of some concern. The mean values of heavy metals Toxic Units (TUs) were calculated in the following order: Hg (0.75)> Cr (0.41)> Cd (0.27)> As (0.23)> Cu (0.12)> Zn (0.05)> Pb (0.009). Furthermore, the mean contributing ratios of six heavy metals to Toxic Risk Index (TRI) values were 79% for Hg, 11.48% for Cd, 6.16% for Cr, 3.27% for Cu, 0.07% for Zn and 0.01% for Pb. Calculated values of potential ecological risk factor, revealed that the risk of the heavy metals followed the order Cd > Pb > Ni > Cr > V > Cu > Zn. The results reflected that the level of heavy metals, especially Hg and Cd, are on rise due to emerging oil exploration, industrial development, and oil refineries along the entire Gulf. Fe, Mn, Cu, Zn, V and Ni concentrations in seawater were significantly higher (p < 0.05) than the other detected dissolved heavy metals in the sampling sites. A health risk assessment using the hazard quotient index (HQ) recommended by the USEPA suggests that there is no adverse health effect through dermal exposure, and there is no carcinogenic and non-carcinogenic harm to human health.

Copper-Induced Spermatozoa Head Malformation Is Related to Oxidative Damage to Testes in CD-1 Mice

The molecular mechanism for copper toxicity on spermatozoa quality in mice is not well understood. In a 4-week experiment, we challenged 24, 6-week-old male CD-1 mice with twice-a-week intraperitoneal copper chloride injections and evaluated spermatozoa quality, copper levels in the testes, serum testosterone, the expression of key antioxidant glutathione peroxidase 5 (GPx5), and the regulated androgen receptor (AR) in the mice testes. We compared these outcomes for four groups of six mice given doses of 0, 1.25, 2.5, 5.0 mg/kg weight copper chloride twice a week for 4 weeks. The mice demonstrated a copper increase spermatozoa head malformation in a dose-response manner. However, we observed no changes in spermatozoa viability and acrosome integrity in the ratio of mouse body weight to testes weight or in the histomorphology of the testes as the average copper level increased. Results of our RT-PCR assays, immunohistochemical tests, ELISA, and histochemistry analyses indicated that testis GPx5 expression was increased, AR expression in the testes was decreased, serum testosterone was decreased, and the activity of 3β-hydroxysteroid dehydrogenase was decreased as the copper dose increased. In conclusion, these data show that sublethal exposure to copper induces spermatozoa head malformation and influences both mRNA and protein levels of GPx5 and AR which is related to copper resides in the testes.