Elemental sulfur amendment decreases bio-available Cr-VI in soils impacted by leather tanneries

Shi, Jingjing; Chen, Hualin; Arocena, Joselito M.; Whitcombe, Todd; Thring, Ronald W.; Memiaghe, Jeff Nze

Elemental sulfur amendment decreases bio-available Cr-VI in soils impacted by leather tanneries

2016

This study investigated the potential use of elemental S (S0) to convert Cr-VI to Cr-III which should decrease the bio-availability hence, toxicity of Cr-VI in soils. The bio-available fraction of Cr in soil was measured by phosphate buffer extraction (PBE) and the results showed that the fraction is about 10% of the total Cr-VI and varied from 12.8 to 42.5 mg kg−1. The addition of 4.0 mg g−1 S0 decreased PBE Cr-VI to <0.4 mg kg−1 limit established for Cr-VI toxicity in soils. Synchrotron-based X-ray absorption near-edge structure (XANES), X-ray fluorescence (XRF) and micro-XRD revealed that Cr-III was the dominant species (99% of total Cr) and Cr was retained by hematite and goethite in soil. Fe-containing minerals may have provided sufficient protection to render the dominant Cr-III species biochemically inert to redox processes in soils. It is concluded that S0amendment is a promising approach to remediate Cr-VI contaminated soils.

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