Synchrotron‐based X‐Ray Spectroscopy Studies for Redox‐based Remediation of Lead, Zinc, and Cadmium in Mine Waste Materials

• Published in: Journal of environmental quality Vol. 45; no. 6; pp. 1883 - 1893
• Main Authors: Karna, Ranju R., Hettiarachchi, Ganga M., Newville, Matthew, Sun, ChengJun, Ma, Qing
• Format: Journal Article
• Language: English
• Published: United States The American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc 01.11.2016
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2015.12.0616

Several studies have examined the effect of submergence on the mobility of metals present in mine waste materials. This study examines the effect of organic carbon (OC) and sulfur (S) additions and submergence time on redox‐induced biogeochemical transformations of lead (Pb), zinc (Zn), and cadmium (Cd) present in mine waste materials collected from the Tri‐State mining district located in southeastern Kansas, southwestern Missouri, and northeastern Oklahoma. A completely randomized design, with a two‐way treatment structure, was used for conducting a series of column experiments. Two replicates were used for each treatment combination. Effluent samples were collected at several time points, and soil samples were collected at the end of each column experiment. Because these samples are highly heterogeneous, we used a variety of synchrotron‐based techniques to identify Pb, Zn, and Cd speciation at both micro‐ and bulk‐scale. Spectroscopic analysis results from the study revealed that the addition of OC, with and without S, promoted metal‐sulfide formation, whereas metal carbonates dominated in the nonamended flooded materials and in mine waste materials only amended with S. Therefore, the synergistic effect of OC and S may be more promising for managing mine waste materials disposed of in flooded subsidence mine pits instead of individual S or OC treatments. The mechanistic understanding gained in this study is also relevant for remediation of waste materials using natural or constructed wetland systems. Core Ideas In situ treatment additions promoted metal sulfide formation in submerged mine waste materials. The addition of organic C with and without S was capable of inducing metal sulfide formation. Agreement between micro‐ and bulk‐scale XAS metal speciation increased with time of submergence. Mechanistic understanding gained is relevant for remediation of waste materials using natural or CWTS.