Capturing the unknown microbial players and genes involved in the cycling of arsenic and antimony in Northern peatland soils

Increased concentrations of the toxic metalloids arsenic and antimony are encountered in peatlands for a variety of reasons, including input of contaminated ground- or surface water. Mining operations can lead to increased concentrations of arsenic and antimony in peatlands when those are used for mine water treatment, as it is a common practice in Finland. Previous studies of microbial transformations of arsenic and antimony in treatment peatlands at a gold mine in Finnish Lapland indicated, that microbial transformations of arsenic and antimony play indeed an important role in contaminant removal. Moreover, (methyl-)thiolated and methylated arsenic species were detected in the treatment peatlands, arsenic species that have not been detected in many peatlands to date.

However, the studies also revealed many gaps in our understanding of microbial cycling of arsenic and antimony in peatlands, and of the pathways behind the observed transformations of arsenic and antimony. Moreover, it is largely unresolved how arsenic- and antimony-metabolizing microbial communities adapt to high contaminant concentrations in peatlands in Northern climate. Peatlands with naturally high arsenic concentrations pose an ideal site for comparison to reveal differences and similarities in the microbial community composition of peatlands with a long and a short contamination history.

Thus, this project aims to (i) compare the (active) microbial communities and arsenic/antimony-cycle genes in peatlands with different lengths of exposure to arsenic and antimony in high concentrations by metagenomics and –transcriptomics, (ii) resolve pathways in the cycling of arsenic and antimony in peatlands that are so far not sufficiently understood, (iii) identify active microorganisms and genes involved arsenic and antimony cycling and removal in peat soil, (iv) assess the natural changes in microbial activity as well as arsenic and antimony speciation in different seasons, and (v) isolate microorganisms with potential for use in bioremediation of arsenic and antimony contaminated waters and soils. The knowledge gained during this project will deepen our understanding of microbial arsenic and antimony cycling in peatlands and in situ activity of microbial communities involved in contaminant removal from mine waters.