Behavior of Environmental Pollutants in Wetlands and Strategy for Environmental Recovery

为了研究污染物在湿地中的行为，测定了湿地中痕量金属元素（稀土、钍、铀）、多环芳烃（PAHs）和氧稳定同位素比值（即，测定了环境样品中的δ^（18）O）等。在这项研究中，还进行了关于污染物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)春季降水中稀土、钍、铀浓度增加，冬季山区多环芳烃沉降量和浓度增加。降水的δ^（18）O在雨季最小。春季城区大气中PAHs浓度总体呈下降趋势，冬季山区大气中PAHs浓度总体呈上升趋势。(2)酒田潟湖样品沃茨的δ^（18）O值大于新泻县其他环境沃茨，尤其是夏季。这可能与浮游甲壳动物的活动、周围地下水的补给以及蒸发作用等生物过程密切相关。(3)海藻中稀土元素的含量是海水中的10^2-10^3倍，重稀土元素的富集系数大于轻稀土元素。褐藻中铀的含量较高，裙带菜中铀的含量最高。(4)Cr（VI）被还原为Cr（III）的腐殖物质;此外，腐殖物质的还原能力随着pH值的增加而下降。Cr（III）的络合比Cr（VI）的还原进行得更快，并在pH 5时达到最大值。(5)本文所用的氢同位素交换反应方法可用于评价T对环境的影响，MOPAC法和A“-McKay作图法可用于某些物质的实际分析。

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.