Acid sulfate soils: Processes and assessment

Abstract

Acid sulfate soils contain large amounts of iron sulfides, predominantly pyrite, which is readily oxidized once these soils are disturbed and aerated. The acid produced during pyrite oxidation promotes the release of various (trace) metals, restricts nutrient supply and may also corrode steel and concrete structures. Thus, the aeration of acid sulfate soils poses a serious threat to agriculture, water quality, biota and construction. Recently, the North German lowlands have been a focus of acid sulfate soil disturbances (mainly due to construction works). In order to address the resulting challenges, the development of improved methods and the investigation of trace metal mobility and sequestration in acid sulfate soils were a focus of this thesis. An improved chromium-reducible sulfur protocol was developed and a process study from the Mekong River Delta, Vietnam provided new insights on the trace metal cycling in acid sulfate soils. These and other studies were the base for the new guidelines for the assessment of acid sulfate soils presented here. The guidelines were adapted to the situation in the North German lowlands, in particular the widespread occurrence of potential acid sulfate peat soils.