Buddhadeb Chattopadhyay

Assessment of the spatio-temporal distribution of soil properties in East Kolkata wetland ecosystem (A Ramsar site: 1208)

The present investigation was made to characterize spatial and temporal variations in soil properties and to evaluate possible differences that could be dependent on the tannery effluent discharges, municipal sewage discharges, vegetation cover, soil settlement rate, crop rotation, etc. Soil total organic matter (TOM), cations like, Sodium (Na), Ammonium (NH4), Potassium (K), Calcium (Ca) and Magnesium (Mg) contents in the bank soils and bottom sediments were recorded from seven different characteristic sites in East Kolkata wetland ecosystem, a Ramsar site (Ramsar site No. 1208). The profile maps were constructed by geostatistical methods to describe the spatial distribution as well as temporal variations of all the factors to identify the influences of composite wastewaters. The work was initiated to identify causes and consequences of the waste dumping in the concerned region for the past hundred years and thereby to suggest necessary precautionary measures to prevent further loss of soil quality.

A study on the waste metal remediation using floriculture at East Calcutta Wetlands, a Ramsar site in India

Use of specific plant species in remediation of heavy metal-contaminated soil and water was a promising eco-friendly technology. The present study indicated the possibilities of phytoremediation of metal-contaminated (namely Ca, Cr, Mn, Fe, Cu, Zn, and Pb) soil by using plant species important for floriculture of East Calcutta Wetlands, a Ramsar site at the eastern fringe of Calcutta city. Plant species like sunflower (Helianthus annuus), marigold (Tagetes patula), and cock’s comb (Celocia cristata) grew on soil contaminated by industrial sludge and irrigated regularly with wastewater accumulated different metals in different plant parts in varied concentrations. Pot culture study in the laboratory setup was also done to ascertain the efficiency of these plants for ameliorating contaminated soil. It was found that general accumulation patterns of metals concerned in different plant parts were root > leaf > stem > flower. This work indicated the importance of cultivation of economically important, non-edible, ornamental plant species as an alternative cost-effective practice to remediate heavily contaminated farmlands of East Calcutta Wetlands.

Antioxidant response to oxidative stress in zooplankton thrived in wastewater-fed ponds in East Calcutta Wetland Ecosystem, a Ramsar site

The municipal sewage of Calcutta city together with industrial effluents traversed the East Calcutta Wetlands (ECW) (Ramsar Site No. 1208) for nearly a century. The composite wastewater at the ECW, was used for pisciculture and agriculture after natural stabilization. Such uses have always been thought to be a source of contamination to biota and humans. Some water-borne pollutants generate reactive oxygen species including superoxide radical anion (O2−.), hydrogen peroxide (H2O2), and hydroxyl radical (.OH), which are highly reactive and potentially deleterious to biological systems. The present study was initiated to examine the antioxidant activities against oxidative stress during different seasons in body fluids of two zooplankters, Moina micrura and Mesocyclops leuckarti thriving in wastewater-fed ponds of ECW. Results showed significantly higher electrical conductivity, chloride and metal (Cr, Cu, and Pb) concentrations in contaminated wastewater-fed pond (CP) at ECW compared to the uncontaminated village pond (UP). Zooplanktons thriving in CP displayed significantly higher superoxide dismutase and catalase activities at all seasons compared to those in UP. Seasonal variations in antioxidant activities were found to be in agreement with variations in limnochemical factors. Hence, antioxidant activity was used as a biomarker against oxidative damage in plankters surviving under pollutant stress.

Oxidative response of wetland macrophytes in response to contaminants of abiotic components of East Kolkata wetland ecosystem

Abstract The tannery effluent and composite municipal sewage water drained to the East Kolkata wetland (EKW), a Ramsar Site (1208), is used for agriculture and pisciculture after natural stabilization. Such composite wastewater is characterized by exceedingly high total dissolved solids, total hardness, chloride and heavy metals concentrations. These water born pollutants generate reactive oxygen species which are potentially toxic to the biological system. These reactive oxygen species are normally detoxified by some enzymes, such as superoxide dismutase (SOD) and catalase (CAT). The present study was commenced to find out the SOD and CAT activities against the oxidative stress, if any, in four macrophytes namely, Eichhornia crassipes, Pistia stratiotes, Alternanthera sessilis and Sagittarria montevidensis of contaminated ponds (Site 1 and Site 2) of EKW and an uncontaminated site (Control site). During the course of sampling the physico-chemical factors were found significantly higher in the EKW ponds compared to the control site. In the EKW sites, higher rate of evaporation during summer months caused higher elemental concentration in the premonsoon than in other seasons. This led to high activity of both SOD and CAT enzymes. In contrast, heavy rain fall in monsoon lowers the elemental concentration - mainly due to dilution effect. Present experiment indicated that in a stressed ecosystem like EKW, the wetland plants overcome the stress by altering their stress enzyme activities, hence suggesting an evidence of adaptive mechanism to thrive in a stressful environment.

Impact of composite tannery effluent on the amino-transferase activities in a fish biosystem, using Guppy fish (Poecilia reticulata) as an experimental model

Tannery effluents cause serious effects on metabolic functions at the cellular level. Tannery wastewater in East Calcutta wetland, a Ramsar site (no. 1208), is used for pisciculture as well as for irrigating adjacent agricultural farms after natural stabilization. This study was conducted to determine the acute and chronic toxicity of composite tannery wastewater on a fish (Poecilia reticulata) biosystem. The adverse effects of composite tannery effluents on aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities of the liver and gill of P. reticulata were examined. Composite tannery effluent was characterized by exceedingly high total dissolved and suspended solids, chloride, total hardness, and biochemical oxygen demands. The activities of ALT and AST in fish tissues exposed to tannery effluents showed a significant rise with increasing effluent concentrations but they decreased when the exposure period was increased from 4 to 15 days. Our study indicated that the tannery effluent was capable of interfering with the metabolic processes by altering the enzyme activity in liver and gills attributed to cellular injury and following chronic exposure there is evidence of an adaptation mechanism.

Changes in physicochemical characteristics of wastewater carrying canals after relocation of Calcutta tannery agglomerates within the East Calcutta Wetland ecosystem (a Ramsar site)

Calcutta Leather Complex (CLC) near Bantala, Calcutta was constructed in the late 1990s. The ostensible purpose was to bring together the widely dispersed and haphazardly located tanning industry of Calcutta in a single location and to facilitate hazardous waste management by establishing a Common Effluent Treatment Plant. Unfortunately, for a number of reasons, the CLC is not yet fully operational. Further, the continued operation of illegal tanneries outside CLC has worsened matters. This study was undertaken to assess the physicochemical conditions of wastewater carrying canals within the East Calcutta Wetland (ECW) ecosystem (a Ramsar site) with special reference to the relocation of tanneries. Results revealed a great change in the values for physicochemical conditions; most changes were statistically significant (p < 0.05) when compared with available data, previous to tannery relocation. Moreover, the amelioration efficiency of ECW ecosystem was found to be mostly disturbed both by the illegal tannery operations and shifting of tannery agglomerates.

Plasticizing Polystyrene with Waste Leather Buffing Dust: A Drive towards Waste-Polymer Composite Synthesis

This is the first report on the use of waste chrome-tanned Indian leather buffing dust for plasticizing atactic polystyrene (PS). There is no effective re-use of waste leather buffing dust reported till today. This waste material, after preliminary characterization, has been dispersed in solvated polystyrene. Resultant composites prepared therefrom via solution cast method exhibit a drastic drop in surface hardness up to certain modifier concentration, beyond which it increases. Addition of surfactants during dispersion of the buffing dust at the optimum level further reduces surface hardness. Para-toluene sulphonic acid (PTSA) has been found to be a better compatibilizer than more conventional sodium lauryl sulphate (LS) in this system. The compatibilized composites show substantial “yield behaviour” when stretched and the breaking strain has been improved drastically from 0.2% in pure polystyrene to 25% in PTSA compatibilized system without any loss in strength. Accordingly, the breaking energy has been increased to much greater than that of the virgin polymer. Effective plasticization of the composites has lowered the glass transition temperature (Tg); PTSA containing composite has shown the minimum value, possibly due to generation of more free volume around the rigid polystyrene molecules on account of its effective adsorption over finer dust particles. Accelerated thermal degradation study shows greater thermal stability of the composites as compared to virgin polymer and this possibly resulted due to the presence of chromium content in the waste, which acts as heat sinks.