Biological Natural Attenuation and Contaminant Oxidation in Sediment Caps: Recent Advances and Future Opportunities

Capping represents an efficient and well-established remediation practice to contain pollutants in sediments. Coupling capping amendments with biodegradation is an emerging technology with great potential to promote simultaneous sequestration and oxidation of contaminants in situ. Capping materials alter the native sediment environment and affect the biodegradation potential of benthic microbial communities. The placement of materials specifically influences (i) porewater pH and composition, (ii) nutrient fluxes, (iii) electron accepting processes, (iv) bioavailability of contaminants, and (v) biofilm formation. This review summarizes current literature documenting the impact of these alterations on microbial ecology and biodegradation activity, describes recent advances in bioactive sediment caps, and identifies areas where additional research is warranted.