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应用生态学报 ›› 2019, Vol. 30 ›› Issue (6): 1840-1846.doi: 10.13287/j.1001-9332.201906.013

• 稳定同位素生态学专栏 • 上一篇    下一篇

提取方法对土壤水同位素和植物水源分割的影响

马小军1,2, 靳静静3, 司炳成1,2,3,*, 向伟1,2, 王洪秀1,2   

  1. 1西北农林科技大学水利与建筑学院, 陕西杨凌 712100;
    2旱区农业水土工程教育部重点实验室, 陕西杨凌 712100;
    3西北农林科技大学中国旱区节水农业研究院, 陕西杨凌 712100
  • 收稿日期:2018-11-19 出版日期:2019-06-15 发布日期:2019-06-15
  • 通讯作者: * E-mail: bing.si@usask.ca
  • 作者简介:马小军,男,1993年生,硕士研究生. 主要从事土壤水分提取与土壤生态水文过程研究. E-mail: mxjxn2018@163.com
  • 基金资助:
    国家自然科学基金重点项目(K305021308)和“千人计划”实验室运行科研专项(Z111021308)资助

Effects of extraction methods on soil water isotope and plant water source segmentation.

MA Xiao-jun1,2, JIN Jing-jing3, SI Bing-cheng1,2,3,*, XIANG Wei1,2, WANG Hong-xiu1,2   

  1. 1College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100, Shaanxi, China;
    2Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semi-arid Areas of Ministry of Education, Yangling 712100, Shaanxi, China;
    3Institute of Water-saving Agriculture in Arid Areas of China, Northwest A & F University, Yangling 712100, Shaanxi, China
  • Received:2018-11-19 Online:2019-06-15 Published:2019-06-15
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (K305021308) and the Special Fund for Thousand-Talent Plan (Z111021308)

摘要: 选取理化性质不同的两种土壤(壤土与砂土),通过烘干后加入已知同位素值的矿泉水作为参考水进行标记,组成不同质量含水量(壤土: 0.15、0.20、0.30 g·g-1;砂土:0.10 g·g-1)的土-水混合物,随后设置不同的平衡时间(壤土: 3、6、12、24、48、72、96 h;砂土:96 h),确保干燥的土壤颗粒与加入的水分达到很好的混合;采用机械离心和真空冷凝抽提法对平衡后的土壤进行水分提取,并分析其同位素组成.结果表明: 同一含水量、不同平衡时间,机械离心法提取的土壤水同位素组成没有显著差异,但均比参考水的同位素值富集,氢、氧同位素最大差异分别可达7.38‰和1.24‰;然而,真空冷凝抽提的土壤水同位素比参考水偏贫化,氢、氧同位素最大差异分别可达6.27‰和1.03‰,且在低含水量下,其同位素组成随平衡时间(24 h以内)的增加贫化程度不断增大,24 h以后趋于稳定.随土壤含水量增大,两种提取方式对土壤水同位素的影响程度减弱;黏粒含量高的壤土水同位素值比黏粒含量低的砂土更容易受提取方式的影响.通过举例分析发现,提取方式引起的同位素组成差异并不显著影响植物水源分割.

Abstract: 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.