Abstract
Environmental pollution by pentachloronitrobenzene (PCNB) was investigated from 1988 to 1992 at Sugadaira in Nagano prefecture, where large amount of PCNB has been applied. PCNB in high concentration was detected in river water near the agricultural land. In particular, the concentration of PCNB in river water was high in July and August over one month after the application of PCNB, and so the river water pollution by PCNB continued all the year around. As PCNB was detected in rainfall water in June and July, PCNB was presumed to be distributed widely in surroundings. The decrease of the concentration and of the load of PCNB in river water were observed near the wetlands in Sugadaira. Therefore, the degradation of PCNB has progressed in wetlands. Since the high concentrations of total organic halogen (TOX) in river water and groundwater were detected, TOX can be used as an index of pollution by chlorinated pesticides. The concentration of PCNB in river water increased rapidly after rainfall owing to flow and suspension of soil and sediment containing pesticides. Therefore, the rainfall increased the loads of PCNB to river.
