Carp (Cyprinus carpio L.) were exposed to nitrofen (NIP) by different routes (via water or food) to compare bioaccumulation parameters and tissue distribution. The bioconcentration factor of NIP was 5,100, and the lipid-corrected biomagnification factor was 0.137. Growth-corrected elimination half lives were 2.1–3.0 days via aqueous exposure and 2.7–2.9 days via dietary exposure. From either uptake route, the tissue distribution of NIP was highest in the head, followed by muscle, viscera, dermis, digestive tract and hepatopancreas, which was highly correlated with the tissue lipid content. We conclude that the uptake route has no influence on tissue distribution of NIP and that the accumulation potential in tissues depends on the lipid content.

Estuaries are dynamic ecosystems which vary widely in loading of the contaminant methylmercury (MeHg), and in environmental factors which control MeHg exposure to the estuarine foodweb. Inputs of organic carbon and rates of primary production are important influences on MeHg loading and bioaccumulation, and are predicted to increase with changes in climate and land use pressures. To further understand these influences on MeHg levels in estuarine biota, we used a field study approach in sites across different temperature regions, and with varying organic carbon levels. In paired comparisons of sites with high vs. low organic carbon, fish had lower MeHg bioaccumulation factors (normalized to water concentrations) in high carbon sites, particularly subsites with large coastal wetlands and large variability in dissolved organic carbon levels in the water column. Across sites, MeHg level in the water column was strongly tied to dissolved organic carbon, and was the major driver of MeHg concentrations in fish and invertebrates. Higher primary productivity (chlorophyll-a) was associated with increased MeHg partitioning to suspended particulates, but not to the biota. These findings suggest that increased inputs of MeHg and loss of wetlands associated with climate change and anthropogenic land use pressure will increase MeHg concentrations in estuarine food webs.

The bioaccumulation of heavy metals in two fish samples along with the water and sediment samples from the coastal waters of Kalpakkam, Southeast coast of India were investigated in this study. The concentration of the metals in the surface waters were in the order Fe (61.30 to 89.68 µg/L) > Zn (29.45 to 36.44 µg/L) > Pb (2.46 to 4.82 µg/L) > Cu (3.04 to 4.36 µg/L) > Cr (1.86 to 4.09 µg/L) > Mn (2.16 to 2.63 µg/L) > Cd (0.78 to 1.94 µg/L) > As (BDL), whereas the trend in the sediment was Fe (3067.40 to 4545.74 mg/Kg) > Zn (8.34 to 10.69 mg/Kg) > Cr (6.48 to 8.86 mg/Kg) > Pb (0.32 to 0.60 mg/Kg) > Cu (3.59 to 5.07 mg/Kg) > Mn (1.83 to 2.77 mg/Kg) > Cd (1.88 to 2.53 mg/Kg) > As (BDL). The bioaccumulation trend of heavy metals in the fish muscles were Fe (18.71–78.48 mg/Kg) > Zn (15.87–26.27 mg/Kg) > Cu (3.61–4.59 mg/Kg) > Mn (0.8–3.48 mg/Kg) > Cr (0.54–1.45 mg/Kg) > Pb (0.24–0.89 mg/Kg) > Cd (0.27–0.47 mg/Kg) > As (BDL). The Overall Metal Pollution Index and Pollution Load Index results suggest that the coast of Kalpakkam is slightly polluted by heavy metals, where KLP-2 station has higher MPI and PLI compared to other stations. But the Target Hazard Quotient, Bio-Accumulation Factor and Bio-Sediment Accumulation Factor suggest that the marine foods of Kalpakkam are free from heavy metal carcinogenic impacts to humans, despite that, THQ for Cd and Cr is high. It may pose a threat to humans if concentration rises in due time. Spatial and seasonal monitoring regularly is warranted to prevent the health risks of the populace along the coast of Kalpakkam.

We collected water samples from contaminated Buddha Nullah drain in Ludhiana district of Punjab (India) during pre- and post-monsoon seasons of the year 2017 and 2018. The soil and plant (wheat and rice) samples were also taken from fields cultivated near the water sampling sites. The drain is mainly contaminated by discharge of industrial and urban effluents from the surrounding areas and its confluence with Sutlej River (a tributary of the Indus River). Water samples were analysed for nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn). Soil, rice and wheat grain samples were analysed for total metals. Besides this, soil samples were also analysed for and DTPA-extractable metals. The concentration of Cr, Pb and Fe in water exceeded the WHO guidelines during all the seasons. Total Zn, Pb, Mn, Ni and Co concentration in soils exceeded the permissible limits, whereas the average concentration of Fe, Pb, Co and Cd in rice and wheat grains exceeded the permissible limits. The bioaccumulation factor (BAF) for DTPA-extractable heavy metals was in the order: Fe > Cr > Co > Zn > Pb > Cd > Mn > Cu > Ni (BAF values > 1 for all the metals). Heavy metal toxicity load values (HMTL) in water samples were lower than the tolerable toxicity load of heavy metals. However, heavy metal pollution index (HPI) was higher than 100 in all the water samples. Based on the grading of geoaccumulation Index (Igₑₒ), total Cd concentration showed extreme contamination around the soils of Buddha Nullah. The cancer risk associated with heavy metals due to intake of wheat and rice grains and ingestion of soils were in the order: Cd > Ni > Cr. Spatial distribution maps of HPI showed the maximum contamination and health risks were around the areas having higher industrial and urban activities These results suggest that heavy metals particularly Cd cause potential health risks to urban residents and environment. The HPI and HTML for water, Igeo for soils and BAF for plants are useful for assessing heavy metal contamination. The controlling measures must be taken to reduce the heavy metal contamination in the drain by checking of the urban and industrial effluents discharged in it and cleaning of the Buddha Nullah drain should be initiated to improve the water quality of Sutlej River.