Tropical peat biochemical interactions with acid sulphate soils


The expression “Acid Sulphate Soils” pertains to soils, in which the soil formation process has produced, is producing or will produce sulphuric acids in amounts that have a long-term effect on main soil characteristics. In an undisturbed and waterlogged state these soils are relatively harmless. However, when disturbed and exposed to oxygen through drainage or excavation, these soils produce sulphuric acid and thiosulphate.

The formed acids can be partially neutralized by neutralizing bacteria and appropriate chemical environment in soil component while the rest can leach and cause severe acidification in drainage water. The acid attacks clay particles and causes the dissolution of structural aluminium, iron, manganese, and other heavy metals which become available to biota in potentially toxic quantities in soil solution. Combined acidification and toxic elements cause ecologically and economically huge losses such as a loss of vegetation. Furthermore extensive mortality and collapses in the reproduction success of aquatic life may result from acidification and toxins released.

Agriculture or other extensive drainage demanding activities on peat underlain by acid sulphate soil is proven ecologically unsustainable and expensive. The drainage leads to loss of peat and the oxygen-exposed acidic horizon will oxidize releasing acids into peat remnants and drainage water, thus likely leading to severe environmental problems due to heavy acidity and high concentration of toxins in the soil solution. The ecological-, land management-, community related-, and economical problems connected to ASS are known, but the land reclamation process on potentially hazardous peatland areas has continued and neglected future problems with pyrite oxidation. Ecological significance of peat deposits on ASS needs to be studied in order to create tools for mitigation planning and preventing pitfalls of planning in the future.

Specific research objectives in TROPEASS can be divided into three categories; coverage and status, role and function, and future and restoration potential of peatlands on ASS. The central aims are to (i.) estimate current expanse and land use in peat covered acid sulphate soils, (ii.) estimate peat biochemical interactions with acids/toxins released by ASS in differing ecohydrological conditions and peat potential in immobilization (neutralization) of these substances, and (iii.) create timescales for peat area change and ASS activation in relation to current land use activities, and evaluate possibilities to restore (abandoned) mismanaged areas.
This work focuses on clarification of forest ecosystem responses in acidic/toxic conditions created by ASS and its potential putative participation in protection of surrounding agri-/aquaculture from acidification effects. In reclaimed peat areas and abandoned lands the annual hydrological cycle, vegetation and the peat characteristics differ from forested areas, and this can be reflected on the biochemical interaction of peat and acids/toxins released by ASS. By comparing the reactions in forest and reclaimed areas it is possible to validate the environmental effects of these land use types. If forested ecosystems prove to have marked influence on reducing malicious effects of acidification in certain preconditions, it is possible to examine and valuate the rehabilitation potential of mismanaged abandoned ASS areas.

Cooperative organizations are: University of Helsinki -coordination (Finland), Agrifood Research Finland (Finland), Can Tho University (Vietnam), Gadjah Mada University (Indonesia), Indonesian Agency for the Assessment and Implementation of Technology (Indonesia), and Ludwig Maximilians University Munich (Germany).
Period: 2007 – 2010
Client/donor: Government of Finland (Academy of Finland)

Further information is provided by Jyrki Jauhiainen and Harri Vasander