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

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

  • Exposure to respirable and fine dust particle over North-Central India: chemical characterization, source interpretation, and health risk analysis 2019-12-10


    This study enhances the understanding of the particulate matters (PM2.5 and PM10) and their physical and chemical behavior over the Taj Mahal, Agra, in North-Central India. The mass concentration was determined, and the shape and size of the particles and chemical characterizations have been carried out using SEM–EDX. The high level and significant variation of PM10 (162.2 µg m−3) and PM2.5 (83.9 µg m−3) were observed. The exceedance factor of the present study region is in critical and moderate condition. Morphological characterization reveals the particles of different shapes and sizes, while elemental analysis shows the presence of Si, Al, Fe, Ca, K, Cl, Mg, Na, Cu, and Zn. The dominance of Si indicated the contribution of natural sources, i.e., soil over this region. Three significant sources, viz. soil/road paved dust/vegetative emissions, vehicular/industrial emissions, and intermingling of dust and combustion particles, have been identified using principal component analysis over North-Central India. Health risk analysis of particulate matter identified carcinogenic and non-carcinogenic metals in the present study, which comes in contact with human beings during inhalation. The non-carcinogenic risk was much higher than the acceptable level. The high carcinogenic risks were found in Zn in PM10 and Cu in PM2.5 for both children and adults.

  • Integration of remote sensing data and in situ measurements to monitor the water quality of the Ismailia Canal, Nile Delta, Egypt 2019-12-10


    The Ismailia Canal is one of the most important tributaries of the River Nile in Egypt. It is threatened by extinction from several sources of pollution, in addition to the intersection and nearness of the canal path with the Bilbayes drain and the effluent from the two largest conventional wastewater treatment plants in Greater Cairo. In this study, the integration of remote sensing and geospatial information system techniques is carried out to enhance the contribution of satellite data in water quality management in the Ismailia Canal. A Landsat-8 operational land imager image dated 2018 was used to detect the land use and land cover changes in the area of study, in addition to retrieving various spectral band ratios. Statistical correlations were applied among the extracted band ratios and the measured in situ water quality parameters. The most appropriate spectral band ratios were extracted from the NIR band (near infrared/blue), which showed a significant correlation with eight water quality metrics (CO3, BOD5, COD, TSS, TDS, Cl, NH4, and fecal coliform bacteria). A linear regression model was then established to predict information about these important water quality parameters along Ismailia Canal. The developed models, using linear regression equations for this study, give a set of powerful decision support frameworks with statistical tools to provide comprehensive, integrated views of surface water quality information under similar circumstances.

  • Geophagy among East African Chimpanzees: consumed soils provide protection from plant secondary compounds and bioavailable iron 2019-12-01


    Geophagy, the intentional consumption of earth materials, has been recorded in humans and other animals. It has been hypothesized that geophagy is an adaptive behavior, and that clay minerals commonly found in eaten soil can provide protection from toxins and/or supplement micronutrients. To test these hypotheses, we monitored chimpanzee geophagy using camera traps in four permanent sites at the Budongo Forest Reserve, Uganda, from October 2015–October 2016. We also collected plants, and soil chimpanzees were observed eating. We analyzed 10 plant and 45 soil samples to characterize geophagic behavior and geophagic soil and determine (1) whether micronutrients are available from the soil under physiological conditions and if iron is bioavailable, (2) the concentration of phenolic compounds in plants, and (3) if consumed soils are able to adsorb these phenolics. Chimpanzees ate soil and drank clay-infused water containing 1:1 and 2:1 clay minerals and > 30% sand. Under physiological conditions, the soils released calcium, iron, and magnesium. In vitro Caco-2 experiments found that five times more iron was bioavailable from three of four soil samples found at the base of trees. Plant samples contained approximately 60 μg/mg gallic acid equivalent. Soil from one site contained 10 times more 2:1 clay minerals, which were better at removing phenolics present in their diet. We suggest that geophagy may provide bioavailable iron and protection from phenolics, which have increased in plants over the last 20 years. In summary, geophagy within the Sonso community is multifunctional and may be an important self-medicative behavior.