Biogeochemical Dynamics in Forested Watershed during Winter

在日本中部的Tohkamachi进行了冬季降水的化学研究。冬季降水样品中的Cl^-/Na^+和Mg^<2+>/Na^+比值与海水中的比值接近。这一结果表明，在冬季降水中发现的Na^+、Mg^+和Cl^-来源于海水。确定了冬季降水样本中Na^+浓度与对流混合层高度之间的关系。含有海盐颗粒的云滴被认为是通过降雨过程被雪晶捕获的。结果表明，对流混合层高度越高，雪晶对海盐粒子的收集率越大。在<18>几种产生冬季降水的天气条件下，确定了冬季降水中δ ^ O值与对流混合层顶气温的关系。样本p中的delta^<18>O值 关于我们 冬季风条件下的降水量大于其他天气条件下的降水量。在冬季风条件下，对流混合层顶温度与冬季降水样点δ ^ O有良好的相关性<18>，本文研究了一个野外、一个落叶林和一个针叶林样点雪包中阴离子浓度和生物活性的变化。积雪中主要阴离子的浓度在针叶林站点高于在开放的网站和落叶林站点。主要阴离子的浓度随着融雪的进行而逐渐降低。积雪中PO_3 ~-浓度<3->随融雪进程的增加而增加。针叶林雪包中叶绿素a的浓度高于开阔地和落叶林。在融雪季节，落叶林和针叶林雪包中叶绿素a的浓度增加。雪藻的活动被认为是在融雪季节活跃。通过室内培养实验，针叶林样地的NO_3^-可能被雪藻消耗。通过培养实验估计栅藻从积雪中消耗的氮为220 mg/l。在福岛县会津田岛的一个小森林流域进行了溪流水化学研究。试验流域位于温带雪气候区，面积0.14平方公里。流域基岩由新近纪形成的固结沉积物组成。该流域完全被森林植被覆盖。月降水量最大值出现在夏季，而月径流量最大值出现在融雪期。积雪融水稀释了溪流中HCO_3^-的浓度，在融雪季节，Cl^-、NO_3^-和SO_4^-的浓度呈阶段性增加<2->。融雪期河水pH值低于夏秋两季。河水的离子组成随季节而变化。Cl^-+NO_3^-+SO_4^-的比值<2->在融雪期增大。少

A chemical study of the winter precipitation was conducted in Tohkamachi, central Japan. The ratios of Cl^-/Na^+ and Mg^<2+>/Na^+ found in the winter precipitation samples were nearly equal to those of sea water. This result suggests that Na^+, Mg^+, and Cl^- found in the winter precipitation are originated from sea water. A relationship was determined between the Na^+ concentration in the winter precipitation sample and the height of the convective mixing layr. Cloud droplets containing sea salt particles are believed to be captured by snow crystals through the rain-out process. The results indicate that the higher the convective mixing layr heights, the larger the rate of collection of sea salt particles by the snow crystals. A relationship between the delta^<18>O values in the winter precipitation and the air temperature at the top of convective mixing layr was determined for several synoptic weather conditions which produced winter precipitation. The delta^<18>O values in samples p … More recipitated under conditions winter monsoon were found to be larger than those under other weather conditions at the same temperature. A good relationship is observed between the temperatures at the top of convective mixing layr and the delta^<18>O of samples of winter precipitation under conditions of the winter monsoon.The variations of anion concentration and biological activity in the snow packs were studied at an open site, a deciduous forest site and a coniferous forest site. Concentrations of major anions in the snow pack are higher at the coniferous forest site than at both the open site and the deciduous forest site. Concentrations of major anions gradually decrease as the snowmelt progressed. Concentration of PO_3^<3-> in the snow pack increases as the snowmelt progressed. Concentration of chlorophyl-a in the snow pack is higher at the coniferous forest site than at both the open site and the deciduoud forest site. Concentrations of chlorophyl-a in the snow pack at both deciduoud and coniferous forest site increase during the snowmelt season. Activity of snow algae is considered to be actively during the snowmelt season. By the incubation experiment, NO_3^- of the sample collected at coniferous forest site is consumed probably by the snow algae. Consumption of nitrogen by Scenedesmus is estimated by the incubation experiment as 220 mg/l from the snow pack.Chemical studies of the stream water in a small forested watershed were conducted at Aidzu-Tajima, Fukushima prefecture. The experimental watershed is located under the snowy temperate climate, and has an area of 0.14 km^2. The bedrock of the watershed consists of consolidated sediment formed in the Neogene. The watershed is entirely covered with forest vegetation. Maximum monthly precipitation is observed in summer ; however, maximum monthly runoff is recorded in snowmelt season. The HCO_3^- concentration of stream water is diluted by snow meltwater, and episodic increase of concentrations of Cl^-, NO_3^- and SO_4^<2-> is observed during the snowmelt season. The pH of stream water is lower during the snowmelt season than summer and autumn. The ionic composition of stream water is variable according to the seasons. Bicarbonate is the major anion in summer, and the ratio of Cl^-+NO_3^-+SO_4^<2-> increases in snowmelt season. Less