Nitrata pollution of groundwater arising from agricultural practices, and some technologies to conrol the polluion

为弄清宫古之桥流域地下水硝酸盐污染状况，连续多年对800余口墙水进行了硝态氮含量测定。总样品中有12%的样品硝酸盐氮超过10 ppm。动物粪便被认为是该地区壁水中硝酸盐氮的主要来源之一。其中，具有仲胺基团的壳聚糖衍生物显示出对硝酸根阴离子的高选择性，而不是氯离子和硫酸根阴离子。以硝酸根离子为模板的壳聚糖衍生物在中性附近对硝酸根离子表现出较强的吸附能力，采用苯乙烯-二乙烯基苯共聚法，在不同条件下制备了以氮肥为芯材的微胶囊，控制了芯材的释放，具有一定的防治地下水污染的能力。发现孔径和粒径的大小受制备条件的控制。研究发现，制备了含80%芯材的微胶囊。

To clarify the nitrate pollution of groundwater in Miyakonozyo basin, nitrate-N content of some 800 of wall-water was measured for several years. Twelve% of total samples exceeded 10 ppm nitrate-N.Animal waste was considered to be one of main sources of nitrate-N in wall-water in this region.Removal and separation of nitrate anion were carried out using chitosan and chitosan derivatives. Among these, the chitosan derivatives having the secondary amine group showed the high selectivity for nitrate anion over chloride and sulfate anions. The chitosan derivative with the template of nitrate anion exhibited a high adsorption of nitrate anion at pH value around neutrality.Microcapsule containing nitrogen fertilizer as a core-material were prepared using stirene-di-vinylbenzene co-polymerization for various conditions, in which they control the release of the core-materials and have a ability of prevention of groundwater pollution. Shapes and diameters of the pore and the particle sizes were found to be controlled by the preparation conditions. The microcapsule containing 80% of core-materials was found to be prepared in the study.