THE EFFECT OF ACID SULPHURIC SOIL RESTRAINT BY GROUNDWATER CONTROL IN NAKHON-NAYOK PROVINCE, THAILAND

摘要

Nakhon Nayok Province, Thailand, is located in the floodplain area and has severe problems regarding acid soil which contains sulphide bearing material resulting in soil pH below 4.0. The objectives of this study are to investigate the geochemical variation that occurs under a groundwater controlling condition above the acid materials while other field factors are maintained in natural condition and to study the groundwater controlling technique to alleviate the acidic condition. The field experiment is designed in order to control groundwater level within a time period. The effects on the chemistry of groundwater, surface water, porewater and the soil itself are also monitored. The result reveals that acidity of the soil increases initially from the soil disturbance and the acidity decreases afterwards as a result of the groundwater controlling condition. This finding is also confirmed by the water chemical changes. Several cations are released into porewater when acidity increases and these metals can be hazardous to plants, foundations, and humans. From this study, we conclude that soil disturbance from any activity can stimulate the acidity of the acid sulphate soil, and maintaining groundwater level above the parent material can help alleviate the acidity.