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To efficiently mitigate bacterial mediated acid and metal discharge from acid sulfate soils, iron-and sulfur-oxidizing microorganisms that catalyze the iron sulfide dissolution should be inactivated. An organic carbon source could further be introduced into the soil to promote the growth of iron- and sulfur-reducing bacteria. In this study, acid sulfate soil was amended with a mobile form of ultrafine calcium carbonate alone or in combination with fractions of peat, sodium acetate, or sodium lactate. The introduction of ultrafine calcium carbonate resulted in a raised pH that appeared to inactivate the acidophiles, but did not reactivate iron- or sulfur-reducing bacteria. The addition of organic matter resulted in higher microbial diversities and retention of metals, although acid-tolerant and acidophilic microbes still dominated. A low abundance of an iron-reducing bacteria was identified in the all treatments with both peat fractions and pure organic carbon compounds. These results indicated that biodegraded peat could be used as an energy source for at least iron-reducing bacteria in the acid sulfate soil at the same time as it retains metals in the soil. These findings are of value for further developing mitigation methods for the sustainable use of acid sulfate soils.

Natural sulfide rich deposits are common in coastal areas worldwide, including along the Baltic Sea coast. When artificial drainage exposes these deposits to atmospheric oxygen, iron sulfide minerals in the soils are rapidly oxidized. This process turns the potential acid sulfate soils into actual acid sulfate soils and mobilizes large quantities of acidity and leachable toxic metals that cause severe environmental problems. It is known that acidophilic microorganisms living in acid sulfate soils catalyze iron sulfide mineral oxidation. However, only a few studies regarding these communities have been published. In this study, we sampled the oxidized actual acid sulfate soil, the transition zone where oxidation is actively taking place, and the deepest un-oxidized potential acid sulfate soil. Nucleic acids were extracted and 16S rRNA gene amplicons, metagenomes, and metatranscriptomes generated to gain a detailed insight into the communities and their activities. The project will be of great use to microbiologists, environmental biologists, geochemists, and geologists as there is hydrological and geochemical monitoring from the site stretching back for many years., Measurement(s)rRNA_16S • Metagenome • transcription profiling assayTechnology Type(s)amplicon sequencing • DNA sequencing • RNA sequencingFactor Type(s)biological replicate • sampling depthSample Characteristic - Environmentsoil biocrustSample Characteristic - LocationFinland Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.9901265