SEGH Articles

Is the Indian Sundarban and adjacent regions polluted by mercury? A case study and cross sectional view

05 June 2014
The Indian Sundarban and its adjacent regions are experiencing huge population loads in terms of domestic and industrial effluents from upstream highly urbanized Calcutta and surroundings


The Indian Sundarban comprises 40% of the largest delta formed at the confluence of Bay of Bengal by sedimentation of River Ganges and its tributaries. The region is a unique ecosystem type comprised of mangrove wetlands, tidal creeks, lowlands and mudflats. The main occupation of the coastal population is mainly farming and fishing with some others. The Indian Sundarban and its adjacent regions are experiencing huge population loads in terms of domestic and industrial effluents from upstream highly urbanized Calcutta and surroundings. The region is comparatively less explored in terms of ecological and toxicological health hazards. During the last two decades a number of studies have revealed the pollution status of this important region confirming that the region is getting contaminated by a number of pollutants. These include heavy metals, persistent organic pollutants, organotins in biotic and abiotic compartments of the ecosystem.

Mercury is among the toxic heavy metals considered as one of the priority pollutants by international agencies. Mercury has the ability to enter the food chain in the form of organo-mercury (methyl, ethyl) and biomagnify in higher trophic levels. So human corresponding to the higher trophic positions depended on fish meal for protein and Omega-3 fatty acids are at higher risk from mercury. After the incidence of Minamata, Japan raising concerns on the health impacts of mercury on biota and human beings from fish consumption on global scale. There is very little known about the mercury contamination and human exposure in Indian Sundarban which houses about 172 species of fishes and majority of the population depends fish as a major protein source. With this objective a collaborative research work was undertaken with the Centre for Environmental Geochemistry at the British Geological Survey, funded by the Commonwealth Scholarship Commission UK, to perform a case study of mercury pollution in abiotic (sediment) and biotic matrices of Indian Sundarban and adjacent regions.

The samples were collected based on the standard protocols and availability of the biota. The HgT was measured using The Total mercury analyzer (TMA, Milestone). As expected, the sediment was lowest in HgT concentration (0.008 µg g-1 to 0.056 µg g-1). The trend of HgT accumulation in biota was polychaete>fish>bivalve mollusks. Since mercury (in the form of methylmercury) bioaccumulates along the food chain, it was expected that fish would have highest values of HgT among the biota because of its higher trophic position. However, in this study trophic position was not proved to be the key factor to control HgT accumulation. Also the habitat preference (e.g., deposit feeders) could be an important factor for determining the HgT concentration in biota. However, among fishes, carnivorous species tend to accumulate high HgT than that of others. Also the diet (i.e., proportion of feed like polychaetes as food) and exposure time to mercury are important factors controlling HgT concentration. The study revealed that the HgT concentration was lower compared to other studies in the world. Although the overall concentration is low due to a number of operational factors, the highest concentration in biota (polychaete) revealed above the prescribed values, indicating further extensive studies (2014).

A cross-sectional study to ascertain the human exposure of HgT was done by Chatterjee et al., (in press). In this study the authors performed a survey and analysis on the local coastal residents (Sagar Island, Sundarban, India), majority of whom are fisherfolks. The study mainly focused on the human exposure of HgT (via hair biomarker analysis) in terms of fish intake (via dietary survey). In this study, fishes showed low mercury values (0.01-0.11 µg g-1 dry weight) while hair mercury ranged from 0.25- 1.23 µg g-1 dry weight. Hair mercury concentration was highly correlated with the fish consumption frequencies. We didn’t find any influence of age, gender and occupation on the mercury levels. The concentration of HgT in scalp hair revealed baseline information on mercury exposure of fisherfolk population in Indian Sundarban. We need further study considering more participants of different socio-economic groups and diet patterns to comment on the human exposure status of mercury in this region.

Dr. Chatterjee is now a Research Associate in Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India.

Dr. Mousumi Chatterjee, ( former CSIR research associate in Department of Marine Science, University of Calcutta, India


Chatterjee M, Sklenars L, Chenery S R, Watts M J, Marriott A L, Rakshit D, Sarkar S K. (2014). Assessment of Total Mercury (HgT) in Sediments and Biota of Indian Sundarban Wetland and Adjacent Coastal Regions, Environment and Natural Resources Research, 4, 2, 50-64.

Kwokal, Z., Sarkar, S. K., Fransiškovic-Bilinski, S. W., Bilinski, H., Bhattacharya, A., Bhattacharya, B. D., & Chatterjee, M. (2012). Mercury concentration in sediment cores from Sundarban mangrove wetland, India, Soil and Sediment Contamination An International Journal, 21(4), 525-544.

Antizar-Ladislao,B., Sarkar, S, K., Anderson, P., Peshkur, T., Bhattacharya, B.D., Chatterjee, M., Satpathy, K. K. (2011). Baseline of butyltin contamination in sediments of Sundarban mangrove wetland and adjacent coastal regions, India. Ecotoxicology 20:1975–1983. DOI 10.1007/s10646-011-0739.

Chatterjee, M., Canario, J., Sarkar, S. K., Branco, V., Bhattacharya, A., & Satpathy, K. K. (2009). Mercury enrichments in core sediments in Hugli–Matla–Bidyadhari estuarine complex, north-eastern part of the Bay of Bengal and their ecotoxicological significance. Environmental Geology, 57, 1125-1134.

Chatterjee, M., Silva-Filho, E. V., Sarkar, S. K., Sella, S. M., Bhattacharya, A., & Satpathy, K. K. (2007). Distribution and possible source of trace elements in the sediment cores of a tropical macrotidal estuary and their ecotoxicological significance. Environment International, 33, 346-356.

Keep up to date

SEGH Events

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Assessment of the toxicity of silicon nanooxide in relation to various components of the agroecosystem under the conditions of the model experiment 2018-08-18


    Investigation of SiO2 nanoparticles (NPs) effect on Eisenia fetida showed no toxic effect of the metal at a concentration of 250, 500 and 1000 mg per kg of soil, but conversely, a biomass increase from 23.5 to 29.5% (at the protein level decrease from 60 to 80%). The reaction of the earthworm organism fermentative system was expressed in the decrease in the level of superoxide dismutase (SOD) on the 14th day and in the increase in its activity to 27% on the 28th day. The catalase level (CAT) showed low activity at average element concentrations and increase by 39.4% at a dose of 1000 mg/kg. Depression of malonic dialdehyde (MDA) was established at average concentrations of 11.2% and level increase up to 9.1% at a dose of 1000 mg/kg with the prolongation of the effect up to 87.5% after 28-day exposure. The change in the microbiocenosis of the earthworm intestine was manifested by a decrease in the number of ammonifiers (by 42.01–78.9%), as well as in the number of amylolytic microorganisms (by 31.7–65.8%). When the dose of SiO2 NPs increased from 100 to 1000 mg/kg, the number of Azotobacter increased (by 8.2–22.2%), while the number of cellulose-destroying microorganisms decreased to 71.4% at a maximum dose of 1000 mg/kg. The effect of SiO2 NPs on Triticum aestivum L. was noted in the form of a slight suppression of seed germination (no more than 25%), an increase in the length of roots and aerial organs which generally resulted in an increase in plant biomass. Assessing the soil microorganisms’ complex during introduction of metal into the germination medium of Triticum aestivum L., there was noted a decrease in the ammonifiers number (by 4.7–67.6%) with a maximum value at a dose of 1000 mg/kg. The number of microorganisms using mineral nitrogen decreased by 29.5–69.5% with a simultaneous increase in the number at a dose of 50 mg/kg (+ 20%). Depending on NP dose, there was an inhibition of the microscopic fungi development by 18.1–72.7% and an increase in the number of cellulose-destroying microorganisms. For all variants of the experiment, the activity of soil enzymes of the hydrolase and oxidoreductase classes was decreased.

  • Seasonal characteristics of chemical compositions and sources identification of PM 2.5 in Zhuhai, China 2018-08-16


    Fine particulate matter is associated with adverse health effects, but exactly which characteristics of PM2.5 are responsible for this is still widely debated. We evaluated seasonal dynamics of the composition and chemical characteristics of PM2.5 in Zhuhai, China. PM2.5 characteristics at five selected sites within Zhuhai city were analyzed. Sampling began on January 10, 2015, and was conducted for 1 year. The ambient mass concentration, carbon content (organic and elemental carbon, OC and EC), level of inorganic ions, and major chemical composition of PM2.5 were also determined. Average concentrations of PM2.5 were lower than the National Ambient Air Quality Standard (NAAQS) 24-h average of 65 μg/m3. The daily PM2.5 concentration in Zhuhai city exhibited clear seasonal dynamics, with higher daily PM2.5 concentrations in autumn and winter than in spring and summer. Carbon species (OC and EC) and water-soluble ions were the primary components of the PM2.5 fraction of particles. Apart from OC and EC, chemical species in PM2.5 were mainly composed of NH4+ and SO42−. There was a marked difference between the summer and winter periods: the concentrations of OC and EC in winter were roughly 3.4 and 4.0 times than those in summer, while NH4+, SO42−, NO3, and Na+ were 3.2, 4.5, 28.0, and 5.7 times higher in winter than those in summer, respectively. The results of chemical analysis were consistent with three sources dominating PM2.5: coal combustion, biomass burning, and vehicle exhaust; road dust and construction; and from reaction of HCl and HNO3 with NH3 to form NH4Cl and NH4NO3. However, additional work is needed to improve the mass balance and to obtain the source profiles necessary to use these data for source apportionment.

  • Estimates of potential childhood lead exposure from contaminated soil using the USEPA IEUBK model in Melbourne, Australia 2018-08-14


    Soils in inner city areas internationally and in Australia have been contaminated with lead (Pb) primarily from past emissions of Pb in petrol, deteriorating exterior Pb-based paints and from industry. Children can be exposed to Pb in soil dust through ingestion and inhalation leading to elevated blood lead levels (BLLs). Currently, the contribution of soil Pb to the spatial distribution of children’s BLLs is unknown in the Melbourne metropolitan area. In this study, children’s potential BLLs were estimated from surface soil (0–2 cm) samples collected at 250 locations across the Melbourne metropolitan area using the United States Environmental Protection Agency (USEPA) Integrated Exposure Uptake Biokinetic (IEUBK) model. A dataset of 250 surface soil Pb concentrations indicate that soil Pb concentrations are highly variable but are generally elevated in the central and western portions of the Melbourne metropolitan area. The mean, median and geometric soil Pb concentrations were 193, 110 and 108 mg/kg, respectively. Approximately 20 and 4% of the soil samples exceeded the Australian HIL-A residential and HIL-C recreational soil Pb guidelines of 300 and 600 mg/kg, respectively. The IEUBK model predicted a geometric mean BLL of 2.5 ± 2.1 µg/dL (range: 1.3–22.5 µg/dL) in a hypothetical 24-month-old child with BLLs exceeding 5 and 10 µg/dL at 11.6 and 0.8% of the sampling locations, respectively. This study suggests children’s exposure to Pb contaminated surface soil could potentially be associated with low-level BLLs in some locations in the Melbourne metropolitan area.