HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wieder, R. K. Search for Related Content PubMed Articles by Wieder, R. K. Agricola Articles by Wieder, R. K.

Diel Changes in Iron(III)/Iron(II) in Effluent from Constructed Acid Drainage Treatment Wetlands

Department of Biology, Villanova Univ., Villanova, PA 19085.

^* Corresponding author (wieder{at}ucis.vill.edu).

ABSTRACT

Within the past decade, over 400 wetlands have been constructed to treat acid coal mine drainage (AMD). This study was undertaken to examine whether the efficiency with which constructed wetlands retain Fe present in AMD changes on a day-night basis. In each of live AMD treatment wetlands, constructed with a different organic substrate (Sphagnum peat with limestone and fertilizer, Sphagnum peat, sawdust, straw-manure, or mushroom compost), hourly sampling of inflow and outflow waters was conducted over a 19-h (July 1990) and 24-h period (May 1991). The chemical composition of the influent AMD was relatively stable over the duration of either sampling period. However, a striking diel pattern of shifts in the relative abundances of Fe²⁺ and Fe³⁺ in outflow waters was observed for both Sphagnum peat wetlands on both sampling dates, and for the straw-manure and mushroom compost wetlands on the May 1991 sampling date. Prior to sunrise, 75 to 100% of the soluble Fe in outflow waters was Fe²⁺; prior to sunset, 62 to 88% of the soluble Fe was Fe³⁺. The documented did shifts in Fe³⁺ vs. Fe²⁺ abundance in outflow waters are greater in magnitude than any previously reported for a natural system and suggest that the cycling of Fe in AMD treatment wetlands is more dynamic than previously recognized and that standard daytime only sampling protocols are inadequate for assessing Fe retention-release in AMD treatment wetlands.