Laboratory mesocosm studies of Fe, Al, Mn, Ca, and Mg dynamics in wetlands exposed to synthetic acid coal mine drainage.

摘要: To evaluate the potential for constructed wetlands to treat acid coal mine drainage, six model wetland mesocosms (each 2.4 m × 15 cm) were filled with Sphagnum peat (15 cm deep), planted either cattails (Typha latifolia) and living Sphagnum, only, or left as bare (2 per treatment). The exposed synthetic drainage (pH 3.5, concentrations of Fe2+, Al3+, Mn2*, Ca2+, Mg2+ 78.8, 10.0, 5.2, 12.0, 4.5 mg L−1, respectively) at a rate 90 mL min−1, 6 hr d−1, 5 d wk−1, over 16 week period. Chemical analysis periodic intervals indicated that net sources Mn2+ Ca2+ Mg2+, but sinks Fe2+. Type vegetation had no significant effect on Fe2+ retention; 204 g added systems, 162 retained. Formation Fe oxides accounted 73 86% Fee' retention, exchangeable contributing 0.2 1.2%, organically bound 4 19%, residual 7 15% total retention. retention was greatest inflow ends where appeared reach saturation final concentration in 235 g−1. At application we estimated systems would have reached complete after 157 days. We suggest mesocosm approach could be useful generating site-specific data can applied formulation cost-benefit analyses compare proposed treatment system alternative conventional chemical methods treating drainage.