Rao Quan Feasibility Study - Phase 1: Toxic Substances and Contamination (Final Report)

摘要

Due to wartime activity in the Khe Sanh area, it was expected that damming of the river Rao Quan could wash out diffuse pollutants from the ground and from possible military dump sites. As discussed in this report, the rivers Rao Quan, Khe Nghi and Quang Tri contain relatively soft water. The buffer capacity against acidification is good. The sulphate concentration is low. The water will not be aggressive against concrete. The maximum particulate content in the wet season is low. The nutrient content of the rivers is relatively low. The phosphorus content correlated well with the turbidity, which indicates that the phosphorus is bound to particles. Khe Nghi has significantly higher nitrogen content than the other rivers, which may indicate some slight impact from animal husbandry. However, there was no eutrophication. The content of heavy metals is low and indicates no pollution from the military activities in the area. The water is well suited for irrigation. There was no indication from the analysed fish , the river sediments from Rao Quan or the top soil of the rice fields of any significant dioxin contamination. The content was similar to normal back ground levels caused by diffuse atmospheric fallout. The herbicide Agent Orange in 1962-1975 was applied mostly in the southernmost part of the country and contamination from it in the Quang Tri Province is not expected. 13 refs., 4 figs., 4 tabs.