| An acid mine drainage (AMD) treatment system has been developed that uses pulsed, fluidized beds of limestone, and carbon-dioxide pre-treatment of influent AMD, to enhance neutralization of AMD and significantly expand the potential range for application of limestone-based, AMD treatment systems. Laboratory studies were conducted to determine whether effluents produced by this treatment system allow normal biological functioning in stream fishes and macroinvertebrates. Effluents produced by this treatment system are characterized by circum-neutral pH (∼7.5), complete removal of iron and aluminum, and high concentrations of dissolved calcium. Dissolved manganese is not removed from treated effluents, and manganese toxicity to aquatic life has not been well investigated.; Physiological responses by Acroneuria carolinensis and Pteronarcys proteus, and behavioral responses by P. proteus to these effluents were first examined. Nymphs of both species exposed to treated effluents and AMD-free treatments showed no whole-body sodium loss; individuals of both species exposed to untreated AMD experienced significant losses of whole- body sodium. P. proteus drift and feeding behaviors were similar among several treated AMD treatments and an AMD-free treatment, yet were elevated and depressed, respectively, in untreated AMD.; Physiological responses by brook trout (Salvelinus fontinalis ) and slimy sculpin (Cottus cognatus) to treatment effluents were also examined. Brook trout were exposed to two dilutions of treated and untreated AMD (pH 4.2 and 4.7) and AMD-free water. Brook trout exhibited depressed plasma sodium concentrations, elevated plasma glucose concentrations, and neutrophilia in untreated AMD at both dilutions. Plasma sodium and glucose concentrations, and neutrophil abundance remained stable in treated AMD and in AMD-free treatments. Sculpins exposed to untreated AMD showed slightly elevated plasma glucose concentrations, depressed plasma sodium concentrations, and neutrophilia; these responses were not observed in treated AMD treatments nor in AMD-free water.; Our results indicate that the effluents produced by this treatment system, despite containing moderate concentrations of dissolved manganese, are not toxic to these organisms and provide justification for field deployment and further biological testing of this treatment technology in the field. |
