Sukinda Valley, Orissa is known for its chromite ore deposits. The open cast mining for chromium is being carried out since 1950. The extraction of chromite has mostly been carried out by open cast and at few places by under ground mining methods. The possibility of leaching contaminants from the ore material kept in the open ground or from the wastages or degraded ore material produced during the mining processes may contaminate the groundwater in the study area. There is also a high possibility that the contaminants will move to the aquifer system from the seepage of bottom floor of the mining quarry. In order to assess the chemical quality, groundwater samples from different part of the study area for post and pre-monsoon period have been collected and analyzed for various contaminants. This study showed that the groundwater in the study area was nearly neutral to mildly alkaline in pH (6.1 - 7.6) with low to moderate TDS (50 - 507 mg/l). High TSS (4 - 64 mg/l) indicates the influence of mine’s waste on the groundwater quality, because the TSS particles remains as suspended colloidal particles in groundwater and are hence toxic as far as the groundwater potability is concerned. TSS levels are higher than the normal permissible limits of potable water and require a proper filtration process before human consumption. Metallic trace elements such as Cu (0.01 - 1.8 mg/l) and Cr(VI) (0.01 to 0.45 mg/l) are more than the permissible limits at some places in different seasons and my cause health hazards. In general, good groundwater conditions as well as simultaneous dissolution and dilution restraint the chromite and other heavy metals in groundwater.
Key words: Heavy metals, dissolution, dilution, ultramafic rocks.
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