Behavior of Environmental Pollutants in Wetlands and Strategy for Environmental Recovery

为了研究湿地中污染物的行为，测定了环境样品中微量金属元素（稀土、钍、铀）、多环芳烃（PAHs）和氧稳定同位素（δ 18）O)等的浓度。在本研究中，还进行了关于污染物的吸收或吸附的实验室模型实验。因此，主要澄清了以下事项。(1)春季降水中ree、Th、U的浓度增加，冬季山区多环芳烃的沉降量和浓度增加。降水δ^(18) O在雨季最小。春季城区大气多环芳烃浓度普遍下降，冬季山区大气多环芳烃浓度普遍升高。(2)坂田潟湖样水δ^(18) O值大于新泻县其他环境样水，夏季δ^(18) O值尤其大。它与浮游甲壳类生物的活动等生物过程、周围地下水的补给以及蒸发的作用密切相关。(3)海藻中稀土元素浓度约为海水的10^2 ~ 10^3倍，重稀土元素富集系数大于轻稀土元素。褐藻中U的浓度较大，尤以裙带菜最高。(4) Cr（VI）被腐殖质还原为Cr(III)；腐殖质的还原能力随pH的增加而降低，Cr（III）的络合速度快于Cr（VI）的还原，在pH为5时达到最大值。(5)本文采用的氢同位素交换反应方法可用于评价T对环境的影响，某些材料的实际分析可以同时使用MOPAC和A ' ' -McKay图方法。

In order to investigate the behavior of the pollutants in wetlands, the concentrations of trace metallic elements (REEs, Th, U), polycyclic aromatic hydrocarbon (PAHs), and oxygen stable isotope ratios (i.e., δ^(18)O) etc. in environmental samples were measured. In this study, laboratory model experiments regarding the uptake or adsorption of pollutants were also carried out. Consequently, the following matters have been mainly clarified.(1) The concentrations of REEs, Th, U in precipitation increased in spring and the quantity of PAHs deposition and concentration increased at mountains area in winter. In addition, δ^(18) O of precipitations was the smallest in rainy season. The atmospheric concentrations of PAHs generally decreased at urban region in spring, and increased at mountains area in winter.(2)δ^(18) O of sample waters in Sakata lagoon was larger than that of other environmental waters in Niigata Prefecture, and was especially large in summer. It can be closely related to the biological process such as the activity of Crustacea plankton and to the recharge from surrounding groundwater as well as the effect of evaporation.(3) The concentration of REEs in seaweed species were about 10^2-10^3 times higher than those in seawater and the enrichment factor of REEs was larger in heavy REE than light REE. The concentration of U was large in brown algae, especially highest in Undaria pinnatifida.(4) Cr(VI) was reduced to Cr(III) by humic substances; moreover, the reduction ability of humic substances decreased with increasing pH. The complexation of Cr(III) proceeded faster than the reduction of Cr(VI) and reached a maximum at pH 5.(5) The method of hydrogen isotope exchange reaction used in this work is useful for evaluating influence of T on environment, and the actual analysis of some materials can be possible using both the MOPAC and the A "-McKay plot methods.