Impacts of iron and manganese mining activities: Arsenic in marine and wetland sediments

摘要

About 14% of land area of Indian state Goa is under iron and manganese mining. Nearly, 32% of India's iron ore production is from 149 mines in Goa. The wetlands and two major rivers (Mandovi and Zuari) are used for 90% of the iron and manganese ore transport. The 25-30 million tons/year of mining rejects find its way into the wetlands and to rivers during rainy season. The iron ore has approximately 50 μg/g of arsenic concentration and partial dissolution of mining rejects with lesser arsenic levels could lead to high concentration of dissolved arsenic in the wetland systems. The dominant form of arsenic in saline and fresh water regions is inorganic arsenic i.e. arsenate. The total arsenic in coastal waters off Goa is (1.7-4.8 μg/L). About 61% was found as soluble inorganic arsenic and the rest as organic bound arsenic.