JOYSTU DUTTA

and 3 more

Waste water fed pisciculture is nowadays a feature that is common in aquaculture belts across the globe. East Kolkata Wetlands (EKW) is a nature’s wonder where waste water fed natural aquaculture belt is active for more than 70 years now and is efficiently operating as a natural waste management system.The peri urban wetland is also a site of international importance and is listed in Ramsar. Field and lab-based investigations were carried out with three commonly edible carp variety of fishes such as Rohu (Labeorohita), Catla(Catlacatla) and Nile Tilapia (Oreochromisniloticus) collected from ponds (bheries) of the wetland located on the eastern fringes of Kolkata, India. The lab-based analysis reveals the presence of many toxic heavy metals like Lead (Pb), Cadmium (Cd), Chromium (Cr), and Mercury (Hg) in the samples with the seasonal order of accumulation being monsoon >post-monsoon >winter >pre-monsoon in the successive years 2016, 2017 and 2018. The order in which toxic metals are bio-accumulated in fishes is Tilapia>Rohu>Catla. Bioaccumulation of toxic heavy metals shows the trend Pb>Cd>Cr>Hg across all the seasons and years.The ambient media is also investigated to better understand the bioaccumulation pattern at different trophic levels of the ecosystem. Water and sediments were analyzed to evaluate the contamination of toxic heavy metals from point as well as non-point sources. In this study, the observed bioaccumulation pattern of the toxic heavy metals in one of the fragile ecosystems raises questions of environmental management. This study further raises considerable doubt on environmental safety of daily consumed food items.

Tarun Thakur

and 3 more

The present study attempts to understand land use dynamics in an area subjected to opencast and underground coal mining for the last few decades in Kotma Coalmines of Anuppur district in Madhya Pradesh, India through geospatial techniques. Land Use and Land Cover (LULC) change detection analysis was performed digitally classifying Landsat 5 (2001) as well as Landsat 8 (2020) satellite data using maximum likelihood algorithm. Results revealed that area under Dense native vegetation decreased drastically (13.74 sq. km) with the gradual and consistent expansion in the activities of coal mines which showed the highest increase in area over time (15.84 sq. km). Bivariate regression analysis showed the positive empirical relationships between vegetation indices and soil physico-chemical parameters. Studies suggested soil and vegetation is degraded over the large mining areas consistently over a long time period. Despite the continuous reforestation activities on mined areas, the decline area under dense vegetation and sparse vegetation over the twenty-year time-scale indicates that the reclamation activities are still in its’ infancy. Land Degradation Vulnerability Index (LDVI) map was generated to understand the extent of decadal land degradation trends and it shows that 8.60 % of the area is highly vulnerable to degradation. The LDI inputs will help the planners to develop alternate strategies to tackle vulnerability zones for safe mining. Monthly estimation of various meteorological parameters was also recorded to generate heat plots for the period 2001-2020. The study concludes that monitoring and assessment of fragile ecosystems are indispensable for holistic environmental management.