Sukinda chromite valley

Odisha holds about 98% of India's proved chromite reserves, and 97% of these lie in the Sukinda valley, where the largest open-cast chromite mines in the world operate. Mining exposes huge volumes of waste rock to air and water; part of the trivalent chromium in chromite oxidises to hexavalent chromium, which is soluble, mobile and carcinogenic.

According to figures given by Wikipedia, 60% of the drinking water in the area contains hexavalent chromium at more than twice international standards, and about 12 mines operate without adequate environmental controls. In September 2007 the Blacksmith Institute listed Sukinda among the ten most polluted places in the world; some local politicians and scientists disputed the ranking, arguing it rested on outdated data.

Here, unlike many other sites, biological clean-up has actually been tried in the field. Between 2011 and 2023 the group of M. Mohanty and H.K. Patra grew water hyacinth and paragrass in the effluent and contaminated soils of South Kaliapani, measuring reductions in hexavalent chromium; later studies surveyed the wild species that accumulate chromium on the mine ground.