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Use of stable isotopes in the studies on cycling of water and ions in ecosystem.

稳定同位素在生态系统中水和离子循环研究中的应用。

基本信息

批准号：
60860008
负责人：
SAKUMA Toshio
金额：
$ 6.85万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

To solve the problems concerning to the tracer use of deuterium water(HDO) in soils, following studies were conducted : 1) Accuracy of the determination of HDO concentration in purified water samples by using a TCD-gaschromatography, 2) methods to separate and purify the water samples for the analysis, 3)natural abundance of HDO and its fluctuation in marine and terrestrial waters, including soil water.1) The standard error of the determination of HDO concentration by the TCD-gaschromatography was less than +2 ppm when the low HD carrier gas obtained by electrolysis of light water(HDO conc.=11 ppm) was used. 2) A tension lysimeter method was developed to collect the samples of soil solution for the DHO determination in the field. The isotope effect during the extraction was slight when soil water suction was less than 250cmH20. It is concluded that the extraction by the tension lysimeter method is hardly applicable when soil water suction is higher than 300cmH20. 3) Natural abundance of HDO in soils was in the range from 135 to 150 ppm.Some field experiments were conducted to obtain additional information on the application of HDO as a tracer of water under the field condition. During the determination of infiltration capacity by using the double ring infiltrometer, extremely uneven distribution of infiltrated water was noticed. It was concluded that the scale of cylinder was not sufficiently large in comparison with the scale of macropore systems in soils. In field experiments the added HDO was diluted rapidly and was hardly traceable, especially when the soil wetness was high, as in the case of peat soils.

为了解决氘水（HDO）在土壤中示踪使用的问题，进行了以下研究：1）通过使用TCD-气相色谱法测定纯化水样品中HDO浓度的准确性，2）分离和纯化用于分析的水样品的方法，3）HDO在海洋和陆地沃茨中的天然丰度及其波动，1）当电解轻水得到的低HD载气（HDO浓度= 0.0001 ~ 0.0001），用TCD-气相色谱法测定HDO浓度的标准误差小于+2ppm 11 ppm）。2)采用张力蒸渗仪法采集土壤溶液样品，用于田间土壤中DHO的测定。当土壤水吸力小于250 cmH_（20）时，提取过程中的同位素效应很小。当土壤水吸力大于300cmH 20时，张力蒸渗仪法提取土壤水分几乎不适用。3)HDO在土壤中的天然丰度范围为135 - 150 ppm。进行了一些田间试验，以获得在田间条件下应用HDO作为水示踪剂的额外信息。用双环入渗仪测定土壤入渗能力时，发现入渗水量分布极不均匀。结果表明，与土壤大孔隙系统的尺度相比，圆柱体的尺度不够大。在田间试验中，添加的HDO被迅速稀释，并且难以追踪，特别是当土壤湿度高时，如在泥炭土的情况下。