Temperature and microbial activity effects on trace element leaching from metalliferous peats.

1, with concentradrainage for agriculture. Our objectives were to use incubation temtions in aboveground plants as high as 10 g kg 1 . The peratures to vary microbial activity in two metalliferous peats (M7 acidic peat and M3 neutral peat) from the Elba, New York region, high concentration of Zn in drainage water is a threat and to use periodic leaching to assess the extent of trace element to surface and ground water quality, and has raised release from these soils. Dried soils were mixed with glass beads to concern about other toxic trace elements (e.g., Cd) that maintain aeration, moistened, and incubated at 4, 16, 28, and 37 Ci n may be present in the peat and released in soluble forms. 10-cm-diameter 8-cm-tall columns. Five incubation–leaching cycles Acidification, oxidation–reduction shifts, and preferwere performed, each consisting of 7.3 d of incubation (28 d for the ential attachment to dissolved organic matter (facilifinal cycle) followed by 16 h of leaching with synthetic acid rain at tated transport) have been associated with the release 2.5 mm h 1 . Microbial activity was determined initially and after of trace elements from soils into drainage water. Acidifithe final leaching by measuring C mineralization following glucose cation of soils can occur as a result of microbial processes stimulation. Cumulative respiration results were ranked 28 16 (oxidation of organic sulfur and sulfide minerals, nitrifi4 37C, with M7 acidic peat respiration values greater than M3 neutral peat at each temperature. Initial leachate pH levels were cation, nitrogen fixation, and decomposition of organic between 2 and 4, with acidification less pronounced and shorter-lived matter) as well as by depletion of bases by leaching for the M3 peat. Leachate S, dissolved organic carbon (DOC), NO3–N, (Martin and Bullock, 1994). Tipping et al. (2003) meaand trace elements declined with successive leachings (rebounding sured and simulated the release of metals from industrislightly in the final M3 leachate), with concentrations typically greater ally contaminated peats following drought-induced aerin the M7 leachate. Elemental losses followed the same general rank- ation and acidification. ing (28 16 4 37C); losses at 28C were 15 to 22% for As, Cd, Olivie-Lauquet et al. (2001) suggested that the soil Ni, and Zn from the M7 peat; losses from M3 were comparable only microbial population may play a dominant role in confor Cu (1%) and Ni (19%). The correlation of respiration with S, trolling the release of trace elements into water, with DOC, and trace elements losses indicates that microbial processes greater concentrations of trace elements found in summediated the release of trace elements in both peat soils. Neutral M3 peat pH levels limited losses of most analytes. mer months. Among the few studies devoted specifically to the role of microorganisms in metal mobilization, Chanmugathas and Bollag (1987, 1988) concluded that soil microorganisms were responsible for the transforP eat landsare ubiquitous throughout the world, mation and subsequent mobilization of Cd in soil. Pemany of which have elevated levels of heavy metals