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SUMMARY:Modelling Cr contamination and remediation in an Indian mining reg
 ion\; Sukinda Valley - Angus Fotherby\, Cambridge
DTSTART:20260122T113000Z
DTEND:20260122T123000Z
UID:TALK242869@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:Chromium in the oxidised (hexavalent) form\, Cr(VI)\, is an en
 vironmental contaminant due to its solubility and its associated health ri
 sks\, both as a toxin and as a carcinogen.toxicity. Sampling of surface an
 d groundwaters\, complemented by reactive transport modelling was conducte
 d to explore chromium contamination associated with chromite mining in Suk
 inda Valley\, Odisha\, India. Chromium in the hexavalent form\, Cr(VI)\, i
 s an environmental contaminant due to its solubility and toxicity. When in
  its reduced form\, Cr(III)\, it is less toxic and readily precipitates in
 to mineral forms\, limiting its transport. We use field sampling\, laborat
 ory analyses\, and numerical modelling to assess the extent\, controls\, a
 nd dynamics of chromium contamination and to evaluate potential natural at
 tenuation and remediation strategies. Groundwater samples from wells and s
 urface waters within and around Sukinda Valley have significant geochemica
 l variability. Surface waters in the valley exhibit high Cr(VI) concentrat
 ions (up to 0.2 ppm)\, whereas deeper groundwater accessed via pump wells 
 have negligible Cr(VI) and elevated Fe2+ and Mn3+\, indicating naturally r
 educing conditions. Reactive transport modelling demonstrates that microbi
 ally-mediated dissimilatory iron reduction drives Cr(VI) reduction in deep
 er groundwater. We also show that the broader major element composition of
  the groundwater can be explained by equilibrium conditions with common ul
 tramafic weathering minerals\, in concert with this dissimilatory iron red
 uction. Furthermore\, we demonstrate that\, during our sampling\, there is
  little-to-no dilution of mine-tailing wastewater with rainwater before di
 scharge to surface waters (e.g. streams) within the valley\, resulting in 
 Cr(VI) contamination of these waters. We suggest that seasonal variations 
 in rainfall may mitigate acute contamination during monsoon periods throug
 h dilution. We conclude that the deeper\, reducing groundwater tapped by r
 ecently dug pump wells in the region effectively mitigates previously iden
 tified chromium contamination of drinking water in Sukinda but that surfac
 e waters remain impacted by direct runoff from mine-tailing sites. We sugg
 est that enhanced dissimilatory iron reduction\, through addition of organ
 ic matter\, could be a feasible strategy for mitigating surface Cr(VI) con
 tamination.
LOCATION:Open Plan Area\, Institute for Energy and Environmental Flows\, M
 adingley Rise CB3 0EZ
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