Impact of Pollution Sources on the Pong River Water Quality

摘要

The Pong River is an important water source for the upper northeastern provinces of Thailand, especially Khon Kaen Province that uses this river as its sole water supply source. Land use activities along the river, which relate to pollution sources, have an impact on the river water quality. The Pong River reach that is interesting to study is divided into two sections. The first section is the downstream of Ubonratana Dam downstream to the Nong Wai irrigation weir of which the river length is about 34 km. The second section is downstream of Nong Wai irrigation weir to the Mahasarkham Dam of which the length is about 180 km. The major industries situated along the first river section are a pulp and paper mill and a thermal power plant. While sugar, distillery, paper board and tapioca mills are located along the second river section. In addition, there is intensive floating basket aquaculture along the first river section. The irrigation area is mostly along the area of the second river section. Therefore, pollution sources consist at both point of sources including industries, communities and aquaculture, and non-point sources comprising runoff from the irrigation area. Seventeen sampling stations were designated according to the pollution sources to investigate the water quality in terms of general physical and chemical characteristics as well as heavy metals and mutagens. The water quality at these sampling stations were generally similar and classified as moderate water quality. The exceptions were some sampling stations located downstream of the pulp and paper mill and in the part of the river that receives effluent discharge from the municipal wastewater treatment plant which showed higher levels of conductivity, color, COD, and Hg than other stations as well as mutagens. Therefore, the different pollution sources have potential impact on water quality. It is necessary to monitor the water quality of the Pong River by emphasizing some specific parameters including mutagens and heavy metals as these substances could affect bio-accumulations and bio-concentrations in the food chain and thus become a risk to human health.