Biogeochemical and ecological considerations in designing wetland treatment systems in post-mining landscapes

Although wetlands have gained acceptance as important components of ecosyst ems in post-mining landscapes in the past decade their roles in contaminant retention/removal have not been well integrated into the designing of rest oration programs. This paper describes the integration of sediment microbia l activities and natural precipitation processes, along with approaches to defining the contaminant load from the mine wastes. The contaminant removal rates, which can be expected by a wetland sediment, are summarized and how they need to be reflected in the wetland size required, and the carbon sup ply which is needed. Contaminant loading from mining wastes can be balanced by wetland ecological processes, including wetland primary production and microbial mineralization in the sediment. This ecological engineering appro ach is demonstrated using case studies on hard-rock mining waste in Canada. (C) 2001 Elsevier Science Ltd. All rights reserved.