Chromium Pollution

Reference

A report by a joint committee constituted by the National Green Tribunal (NGT) has noted high levels of chromium contamination in groundwater in areas around Sukinda Valley, posing a serious health hazard.

About Chromium

• Chromium is a shiny and hard metal with a high melting point. Its colour is silver-grey. It is obtained from chromite ore.
• Its symbol is Cr and atomic number is 24. It is the third hardest element after carbon (diamond) and boron.
• There are mainly two types of chromium:
  • Trivalent Chromium Cr(III)
  • Hexavalent Chromium Cr(VI)
    • Trivalent chromium Cr(III) is considered essential for a variety of organisms, including humans. It plays an important role in the metabolism of glucose, protein, and fats.
    • Hexavalent chromium Cr(VI) is a highly toxic form of chromium that negatively affects human health as well as the environment and biodiversity. Cr(VI) is produced mostly by human activities.

What is chromium pollution?

• Chromium enters the environment through natural processes and anthropogenic activities, such as mining, smelting, metal processing, industrial production and agricultural activities.
  • This results in pollution and destruction of the ecosystem.
• In India, states like Tamil Nadu (e.g. Ranipet), Uttar Pradesh (e.g. Kanpur), Odisha (e.g. Sukinda Valley) and West Bengal (e.g. Ranaghat-Phulia) are at high risk due to high concentrations of chromium in soil and water.
• Huge quantities of waste from open-cast chromite mining and quarrying operations are directly discharged into water bodies without any treatment.

Effects of Chromium Pollution

Effects on Human Health

• Hexavalent chromium Cr(VI) is considered a carcinogen, increasing the risk of lung cancer.
• Increased levels of chromium in aquatic ecosystems are responsible for eye damage, pulmonary damage, gastrointestinal abnormalities in humans.
• Skin contact with some hexavalent chromium compounds may cause skin ulcers and allergic reactions.

Effects on Agriculture

• Plants absorb hexavalent chromium Cr(VI) from the soil, which hinders their growth and development.
• Chromium exposure reduces soil fertility, which affects food production.
• It hinders crop growth and yield and can reduce their quality.
• According to several studies, chromium pollution negatively affects the metabolic activities of plants.

Impact on environment and biodiversity

• According to studies of the long-term toxicity of Cr(VI) on invertebrates, it enters the body of fish and has lethal effects on the liver and kidneys.
• According to several studies, its concentration in the environment, especially in surface water and groundwater, has increased beyond the prescribed limits.
• Cr(VI) directly or indirectly negatively affects terrestrial plants, aquatic phytoplankton and other organisms.

Solutions to Chromium Pollution

• Several strategies have been adopted for the removal of Cr-metal from contaminated sites, mainly focused on promoting green technologies through various chemical transformations, adsorption, oxidation-precipitation reactions. However, they have their own advantages and disadvantages:
  • For example, chemical-based precipitation technologies have moderately high volumes of wastewater and sludge as by-products, resulting in increased operating costs due to their disposal through dehydration processes.
• Bioremediation is considered as a potential and environmentally friendly approach for the reduction or immobilization of pollutants through microorganisms.
• Some hyperaccumulator plant species significantly reduce Cr from polluted soil and water.
• Currently, nano-particles are emerging as an environmentally friendly alternative to conventional adsorbents. These nano-materials are being considered for the treatment of hazardous Cr containing wastewater.