Using isotopes to determine the contribution of volcanic ash to Sr and Ca in stream waters and plants in a granite watershed, Mt. Tsukuba, central Japan
Using isotopes to determine the contribution of volcanic ash to Sr and Ca in stream waters and plants in a granite watershed, Mt. Tsukuba, central Japan
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使用同位素确定火山灰对日本中部筑波山花岗岩流域溪流水和植物中 Sr 和 Ca 的贡献
DOI：
10.1007/s12665-015-5097-9
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发表时间：
2016
影响因子：
2.8
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Koshikawa Kanao;M.;Watanabe;M.;Shin;K.H. Nishikioria;T.;Takamatsua;T.;Hayashi;S. and Nakano;T.
在日本中部筑波山的一个小森林流域，利用土壤、溪水、植物和大气降水的锶同位素比率来追踪钙（Ca），并确定土壤中的火山灰对森林生态系统中钙循环的影响。陡坡和谷底土壤87Sr/86Sr比值在0.7110 ~ 0.7139之间，表明Sr的主要来源为花岗岩基底（87Sr/86Sr比值为0.7120 ~ 0.7131）。山脊上的土壤87sr /86Sr比值较低（0.7068 ~ 0.7072），表明其主要由3万年前赤城山（0.7069）释放的火山灰物质组成。从谷底到山脊，随着海拔的升高，水体中87sr /86Sr比值减小，Sr（和Ca）浓度升高，表明在上游地区，火山灰是这两种阳离子的主要来源。火山灰源Sr对上游水体和下游水体的贡献分别为50%和0 - 1%。植物的87sr /86Sr比值介于植物生长土壤与大气降水土壤之间（0.7100）。在山脊植物中，超过74%的Sr来自火山灰，而在谷底植物中，Sr < 17%来自火山灰。河流水和植物中Sr（以及Ca）的来源取决于土壤中的火山灰含量，这受到场地海拔的显著影响。
Strontium (Sr) isotope ratios of soils, stream water, plants, and atmospheric precipitation were used to trace calcium (Ca) and to determine the influence of volcanic ash in soils on Ca cycling in forest ecosystems in a small forested watershed on Mt. Tsukuba, central Japan. The87Sr/86Sr ratios of soils on steep slopes and the valley floor ranged from 0.7110 to 0.7139, which indicates that the major source of Sr was the granite substrate (87Sr/86Sr ratio 0.7120–0.7131). Soils on a ridge had lower87Sr/86Sr ratios (0.7068–0.7072), indicating that they were mainly composed of volcanic ash materials released around 30,000 years ago from Mt. Akagi (0.7069). The87Sr/86Sr ratio decreased and the concentrations of Sr (and Ca) increased in stream water with increased elevation from the valley bottom to the ridge, indicating that volcanic ash was the dominant source of both cations in the upstream area. The contributions of volcanic ash-derived Sr to upstream and downstream water were 50 and 0–1 %, respectively. The87Sr/86Sr ratios of plants were between those of the soils in which the plants were growing and those of atmospheric precipitation (0.7100). More than 74 % of the Sr in plants on the ridge, but <17 % in plants in the valley bottom, was volcanic ash-derived. The origin of Sr (and thus Ca) in stream waters and plants varied depending on the volcanic ash content in soils, which was significantly influenced by the site elevation.