[Effects of extraction methods on soil water isotope and plant water source segmentation.]
[Effects of extraction methods on soil water isotope and plant water source segmentation.]
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DOI：
10.13287/j.1001-9332.201906.013
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发表时间：
2019-06
期刊：
影响因子：
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通讯作者：
Xiaomin Ma;Jingjing Jin;B. Si;W. Xiang;Hong Wang
中科院分区：
文献类型：
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作者：
Xiaomin Ma;Jingjing Jin;B. Si;W. Xiang;Hong Wang
采用两种理化性质不同的土壤（壤土和砂土），烘干后加入已知同位素组成的矿泉水作为参比水，配制不同土壤含水量的土水混合物（壤土：0.15、0.20、0.30 g·g-1；砂土：0.10 g·g-1）。之后，我们设置不同的平衡时间（壤土：3、6、12、24、48、72、96小时；沙：96小时）以确保干土颗粒与添加的水充分混合。平衡后采用机械离心和低温真空抽提土壤水，并分析其同位素组成。结果表明，机械离心法提取的土壤水同位素值在相同含水量、不同平衡次数下没有显着差异，但与参考水同位素值相比更为丰富。氢同位素最大富集度为7.38‰，氧同位素最大富集度为1.24‰。相比之下，深冷真空提取法导致土壤水同位素的贫化程度高于参考水，氢和氧同位素的最大贫化率分别为6.27‰和1.03‰。而且，在低含水量下，损耗程度随着平衡时间（小于24 h）的增加而增加，并在24 h后趋于稳定。随着土壤含水量的增加，两种提取方法对提取的土壤水同位素组成影响较小。粘土含量高的壤土的水同位素值比粘土含量低的沙土对提取方法更敏感。提取方法引起的同位素组成差异不影响植物水源分割。
We used two types of soil with different physicochemical properties (loam and sand), oven-dried them, and then added the known isotopic composition mineral water that was reference water to compose the soil-water mixture with different soil water contents (loam: 0.15, 0.20, 0.30 g·g-1; sand: 0.10 g·g-1). After that, we set up different equilibrium time (loam: 3, 6, 12, 24, 48, 72, 96 h; sand: 96 h) to ensure that the dry soil particles were well mixed with the added water. The soil water was extracted by mechanical centrifugation and cryogenic vacuum extraction after equilibrium, and their isotope composition was analyzed. Results showed that the isotopic values of soil water extracted by mechanical centrifugation method had no significant difference in same water content with different equilibration times, but were more enriched compared with the reference water isotopic value. The maximum enrichment for hydrogen and oxygen isotope was 7.38‰ and 1.24‰, respectively. In contrast, cryogenic vacuum extraction method resulted in more depleted soil water isotopes than reference water, with the maximum depletion for hydrogen and oxygen isotope being 6.27‰ and 1.03‰, respectively. Moreover, the degree of depletion increased with the increases of equilibrium time (less than 24 h) at low water content, and became stable after 24 h. With the increases of soil water content, the isotopic composition of the extracted soil water was less affected by the two extraction methods. The water isotope value of loam that had high clay content, was more sensitive to the extraction method than the sandy soil that had low clay content. The difference of isotopic composition caused by extraction methods did not affect the plant water source segmentation.