Delivery of Agricultural Chemicals to Surface and Groundwaters

农业化学品在盆地水平上的行为还没有得到太多的研究。特别是，应深入研究化学品通过流域到河流的流动路径。本研究对长野县Sugadaira盆地的硝酸盐和五氯苯酚的行为进行了研究，特别是在风暴事件期间。主要研究结果如下：1.农田地下水中硝酸盐和硫酸盐是主要的阴离子，其组成取决于其所处的水文地质条件或氧化还原条件。将暴雨过程中河水浓度变化模式划分为4种，反映了化学物质的来源和流动路径。暴雨期间，河水化学成分由上游向下游趋于统一，属于硝酸盐和钙含量较高的农业类型，表明化学物质的来源主要来自周边农田，包括前湿地。风暴期间PCNB的浓度表现出与硝酸盐等其他化学物质不同的模式，PCNB被认为是由悬浮物质通过地表径流带来的。

Behaiviors of agricultural chemicals in a basin level have not been studied much. Especially, flow path of the chemicals through the basin to river should be studied intensively. In this study, behaviors of nitrate and PCNB in the Sugadaira Basin of Nagano Prefecture, especially during storm events, were studied. The results are summarized as follows :1. Nitrate and sulfate are dominant anions in groundwater of agricultural lands whose composition depends on its hydrologeologic conditions or oxdation-reduction conditions.2. Patterns of concentration changes of river water during storm discharge are classified into four, which reflect sources and flow path of the chemicals.3. During storms, chemical compositions of river water are unified from upstream to downstream and shown to be an agricultural type with high concentrations of nitrate and calcium, which shows that sources of chemicals are mainly from surrounded agricultural lands including ex-wetland.4. Concentrations of PCNB during storms show a different pattern from other chemicals such as nitrate and PCNB is supposed to be brought by suspended materials through surface runoff.