Although the environmental hazards of AS soils are globally
identical, the efficiency of mitigation methods may differ depending
on the climatic, crop and soil conditions. In tropical conditions,
waterlogging with tidal seawater can efficiently reduce acid loads
from coastal AS soils, where the generation of alkalinity by anaerobic
carbon metabolism coupled with iron and sulphate reduction
(57–77% of total alkalinity) is assisted by the inherent alkalinity of
seawater (25–42%) (Johnston et al., 2012). The rates of microbial
reactions leading to the reduction of iron and sulphate and consequent
formation of sulphidic materials are strongly temperature
dependent, with higher rates in warmer climates. Therefore, the
results obtained in the (sub)tropics are obviously not directly applicable
to areas with lower temperatures and to environments where
waters may originate from rivers of non-calcareous rain-fed reservoirs,
with alkalinities much lower than in seawater (Hem, 1985;
Stumm and Morgan, 1996). This is the case in AS soils along the
coasts of Finland, which lie in the boreal climate zone and are adjacent
to the brackish Baltic Sea or other virtually non-saline water
bodies.
Recent environmental hazards, including massive fish mortality
on the western coast of Finland (Österholm and Åström, 2008;