SAMPLING ANOXIC PORE WATERS IN PEATLANDS USING PEEPERS FOR IN-SITU FILTRATION

Equilibrium diffusion chambers (''peepers'') have been constructed to collect anoxic pore waters in bogs without degassing and/or oxidizing the samples. These samplers have been constructed of Plexiglass, eithe r as a long board with a series of sampling chambers for close interva l analyses near the surface of a bog, or as single chambers inserted a t greater depths (1 to 6 m). Prior to installation, the chambers have been filled with deaerated, deionized water, and have been covered by a 0.2 mu m membrane filter; this membrane allows the dissolved constit uents in the waters to equilibrate with the deionized water in the cha mber by diffusion. The samplers have been allowed to equilibrate in th e bog for 4 to 6 weeks. Thereafter, they have been withdrawn into N-2- filled glove bags. Individual chambers have been sampled in the field by inserting a syringe through the glove bag; these syringes have been used immediately upon the arrival in the lab to analyze volatile and redox-sensitive species by ion chromatography. The effectiveness of th is sampling approach has been demonstrated by measuring the concentrat ions of the dominant volatile acids in these waters (H2CO3) and two re dox sensitive species (Fe2+ and HS-). The procedure described here sho uld be applicable also to trace metal speciation studies, provided tha t appropriate checks are made for all possible sources of contaminatio n.