地理研究 ›› 2020, Vol. 39 ›› Issue (11): 2537-2551.doi: 10.11821/dlyj020190745

• 论文 • 上一篇    下一篇

基于氢氧稳定同位素的兰州市南北两山土壤蒸发时空变化及影响因素研究

车存伟(), 张明军(), 王圣杰, 杜勤勤, 马转转, 孟鸿飞, 瞿德业   

  1. 西北师范大学地理与环境科学学院,兰州 730070
  • 收稿日期:2019-08-29 修回日期:2020-06-18 出版日期:2020-11-20 发布日期:2021-01-19
  • 通讯作者: 张明军
  • 作者简介:车存伟(1994-),男,甘肃永靖人,硕士,研究方向为全球变化与可持续发展。E-mail: geoche2017@126.com
  • 基金资助:
    国家自然科学基金项目(41771035);甘肃省高等学校科研项目(2018C-02)

Studying spatio-temporal variation and influencing factors of soil evaporation in southern and northern mountains of Lanzhou city based on stable hydrogen and oxygen isotopes

CHE Cunwei(), ZHANG Mingjun(), WANG Shengjie, DU Qinqin, MA Zhuanzhuan, MENG Hongfei, QU Deye   

  1. College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China
  • Received:2019-08-29 Revised:2020-06-18 Online:2020-11-20 Published:2021-01-19
  • Contact: ZHANG Mingjun

摘要:

基于2018年4—10月在兰州市南北两山采集的降水、河水及土壤样品,对不同水体中的氢氧稳定同位素进行测定,并应用Craig-Gordon模型分析了南北两山土壤蒸发的时空变化及其成因。结果表明:① 兰州市局地大气水线LMWL斜率相比全球大气水线GMWL较小,主要是相对湿度小,雨滴在下落过程中受到云下二次蒸发的影响。由表层0~10 cm至深层60~120 cm,土壤水δ2H和δ18O逐渐贫化,土壤水线SWL的斜率均呈现规律性增大,说明表层土壤受到的蒸发分馏最为强烈,随着土壤深度的增加,蒸发分馏逐渐减弱。② 时间变化上,局地蒸发线斜率SLEL在4月较大,土壤蒸发较小,4—6月减小,土壤蒸发增大,6—8月趋于稳定,其中7月土壤蒸发最为强烈,自8月SLEL增大,土壤蒸发开始减小,一直减小至10月。③ 空间变化上,北山相比南山蒸发损失量f更为强烈,主要原因是北山气温、相对湿度和土壤含水量均高于南山。④ 2018年4—10月,各采样点蒸发损失量f达到峰值和谷值的时间相比降水δ 18O均存在明显的滞后,主要原因是降水在土壤基质入渗过程中存在滞留。

关键词: 氢氧稳定同位素, 土壤蒸发, 降水, 兰州市南北两山

Abstract:

Based on the precipitation, river water and soil samples collected from six sampling points in the southern and northern mountains of Lanzhou city from April to October 2018, the stable isotopic of hydrogen and oxygen of different water bodies were determined, and the spatio-temporal changes of soil evaporation in the study area and influencing factors were analyzed. In our paper, we first use water line equation to qualitatively analyze evaporation fractionation strength of different water bodies. Then, we quantitatively calculate the soil evaporation strength based on Craig-Gordon model. The results show that: (1) The slope of local meteoric water line (LMWL) is smaller than that of the global meteoric water line (GMWL), indicating that lower relatively humidity, and raindrop are affected by the sub-cloud secondary evaporation during the precipitation process. From surface layer of 0-10 cm to deep layer of 60-120 cm, the soil water δ2H and δ 18O are gradually depleted, and the slope of the soil water line SWL is regularly increased. The smaller the slope, the stronger the evaporative fractionation, which indicated that the evaporation fractionation of the surface soil is the strongest, and with the increasing soil depth, evaporation fractionation gradually decreases. (2) In terms of the temporal variation, the slope of local evaporation line SLEL is larger in April, indicating that the soil evaporation is smaller, the slope of local evaporation line SLEL began to decrease from April to June, indicating that soil evaporation increases, the SLEL tends to be stable from June to August, and the soil evaporation is more stronger in July. The SLEL began to increase from August, and the soil evaporation began to decrease, and continued to decrease until October. (3) As for the spatial variation, the evaporation loss of northern mountain is more intense than that of southern mountain, which is the fact that the air temperature, relative humidity, and soil water content in north mountain are more higher than those of south mountain. (4) From April to October 2018, the evaporation loss reached the peak value and the valley value showed a significant hysteresis compared with the precipitation δ18O in each sampling point, which is owing to the main reason that there exists hysteresis in the process of precipitation infiltration into the soil matrix.

Key words: stable isotopes of hydrogen and oxygen, soil evaporation, precipitation, southern and northern mountains in Lanzhou city