4.1 Environmental studies of coastal placer minerals
India possesses a vast coastal tract of approximately 7000 km along the eastern and western seaboards with large reserves of placers viz., ilmenite, rutile, leucoxene, zircon, monazite, sillimanite and garnet. ilmenite is the largest constituent of the Indian beach sand deposits, followed by silimanite and garnet.
The occurrence of ilmenite-rich sands have been reported along the Ratnagiri coast, extending from 1 km to 5 km. in length and 100 to 400m wide, located intermittently and spread over a coastal length of 45 km (Gujar et al, 1987 & Gujar et al, 2004). The heavy mineral concentration varies from 20-83% by weight. The cumulative heavy mineral reserves are about 3.45MT out of which ilmenite is 1.67MT. According to the above survey, TiO2 content of Newra deposit is 53% and Kalbadevi is 52%. The above two areas are considered to be potential deposits for future placer exploitation. Similarly, potential deposits of ilmenite, monazite, zircon and garnets have been found on the coasts of Tamilnadu, Andhra Pradesh and Orissa. However, environmental studies have not been undertaken in these areas, to understand the baseline conditions and to predict the possible impacts of mining in these areas.
Potential effects of placer mining are expected to be on the near-shore environment, navigation channels, fishing grounds, breeding grounds, diverse fauna as well as the recreational facilities. The placer areas are known to have diverse flora and fauna in a variety of ecosystems, such as sand dunes, mangroves, sea grass beds, wetlands etc. These are highly productive for commercially important fishes, molluscs, crustaceans and host a variety of bioactive molecules that could be of medicinal importance. Sand dune vegetation is a nature’s line of defense that help the human habitats by catching blowing sand, deflecting wind upwards, retaining fresh water and protecting the hinterland from wave attack and stormy seas.
In view of the significance of coastal environment and the need to preserve it from the impacts of placer mining, the environmental studies for coastal placer minerals has been initiated.
The major activities under this investigation are:
i. Evaluation of environmental conditions associated with different placer minerals along East and West coasts of India
ii. Development of ecological models for prediction of environmental impact of
placer mining
iii. Development of protocols for environmental data collection and monitoring
iv. Creation of environmental database for different placer deposits
The following studies have been conducted under this project:
2002-2003 : Finalized the study area, parameters to be used, and the sampling protocol for collection of data
2003-2004 : Initiated the environmental studies in the intertidal zone. Completed baseline environmental studies, made pits, excavated sand, removed the heavy mineral fraction and dumped the sand back into the pits to simulate the coastal placer mining. Assessed the immediate impact of the disturbance on the coastal ecosystem.
2004-2005 : Studied the seasonal variation of environmental parameters in the same intertidal zone covering the seasons before, during and after the monsoon to understand the natural changes occurring in the area.
2005-2006 : Initiated the environmental studies in the offshore region off Kalbadevi (west coast of India). Baseline studies were followed by environmental impact assessment of the sand mining system deployed by CMERI, Durgapur. Large quantities of sand was lifted from the offshore areas and discharged back. Immediate changes in the environmental parameters were monitored.
2006-2007 : Studied the seasonal variation of environmental parameters in the offshore area covering 3 seasons related to monsoon.
2007-2008 : Conducted environmental studies in the offshore region off Paradip (east coast of India). Baseline studies were followed by environmental impact assessment of the sand mining system deployed by CMERI, Durgapur. Large quantities of sand was pumped from the offshore areas, stored in huge tanks and superficial water was discharged back. Immediate changes in the environmental parameters were monitored
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