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Memory Effects of Soil Layer and Interactions with Subsurface water

土层的记忆效应及其与地下水的相互作用

基本信息

批准号：
09480113
负责人：
TASE Norio
金额：
$ 0.9万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09480113/
关键词：
land use Kanto loam physical and chemical properties of soil soil water groundwater nitrate ion sulfate ion tea plantation

项目摘要

The purposes of this study are to clarity memory effects of soil layers by agricultural activities on the surface for a long time, interactions of soil layers and subsurface water and chemical evolution of groundwater. As a study area, the Kaneko terrace was selected where the soil layer was thick, the ground water level was deep, and the land use, especially the agricultural utilization was long. The nitrate concentration of the groundwater over the Kaneko terrace exceeds 200mg/L, and the effect of the agricultural activity in long time was recognized. Much nitrate and sulfate ions were accumulated in the loam later in tea plantation, and became 10 and two times of the non-fertilized land, respectively. Though the nitrate ion abundantly accumulated all through the layer, the sulfate ion was to surface layer of 4 m. The sulfate ion retained in the soil long after stop of the fertilization. Though the depth profiles of the stable isotope ratios of nitrogen and carbon showed some features which were attributed to the effect of agricultural activity, the relation with the stratigraphy of the loam layer was also considered. From the depth profile of tritium concentration, infiltration rate of soil water was estimated for 1.2m/year. In the depth profiles of the stable isotope ratios of hydrogen and oxygen, there was the periodic fluctuation to the 4m depth, which would retain the recharge patterns and shows the possibility of the estimation of infiltration rate and recharge amount. It was shown that the depth profile of observed nitrate ion was simulated well by the advection-diffusion model with nitrification by the zeroth-order reaction and denitrification by first-order reaction.

本研究旨在阐明长期地表农业活动对土层的记忆效应、土层与地下水的相互作用以及地下水的化学演化。选择土层较厚、地下水位较深、土地利用特别是农业利用较长的金子梯田作为研究区域。金子梯田地下水硝酸盐浓度超过200 mg/L，长期农业活动的影响是公认的。茶园土壤中硝酸盐和硫酸盐离子积累较多，分别是对照地的10倍和2倍。虽然硝酸盐离子在土层中大量积累，但硫酸盐离子主要集中在土壤表层4m处，停止施肥后硫酸盐离子仍在土壤中滞留较长时间。虽然氮、碳稳定同位素比值的深度剖面显示了一些受农业活动影响的特征，但也考虑了与壤土层地层的关系。根据氚浓度深度剖面，估算出土壤水分入渗速率为1.2m/年。在氢、氧稳定同位素比值的深度剖面上，存在4m深度的周期性波动，保留了补给模式，显示了估算入渗速率和补给量的可能性。结果表明，采用零级反应硝化、一级反应反硝化的对流扩散模型能较好地模拟观测到的硝酸根离子深度分布。