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土壤水中稳定同位素的大尺度空间分布是降水同位素与自然环境综合影响的结果,也是陆面过程模拟中不同水体同位素相互作用的重要环节。限于定位监测在反映大尺度土壤水同位素空间特征中的不足,GCM(General Circulation Models)则有助于深入理解土壤水同位素组成变化的空间格局。本文选用LMDZ(free)、LMDZ(nudged)和MIROC(free)3种模拟结果,对中国陆地表层土壤水δ~(18)O的时空分布特征及土壤水δ~(18)O与气温、降水δ~(18)O之间的关系进行研究。结果表明:(1)中国东南地区土壤水δ~(18)O偏大,东北、西北和青藏高原地区土壤水δ~(18)O偏小,其中青藏高原地区δ~(18)O最小;从全国尺度来看,土壤水δ~(18)O变化特征符合降水δ~(18)O的变化特征;1979—2007年,年均土壤水δ~(18)O、夏季土壤水δ~(18)O和冬季土壤水δ~(18)O均呈现上升趋势。(2)土壤水δ~(18)O与气温的相关性较好,温度效应出现在中高纬度地区,距海洋越远,正相关关系越显著。(3)在全国范围内,3种模拟结果均表明,中国土壤水δ~(18)O与降水δ~(18)O普遍呈正相关,说明大多数地区土壤水的补给来自于降水;相关系数在西北地区较大,在东北地区由南至北逐渐递减,在青藏高原地区出现环状分布,相关系数由内向外递增。
The large-scale spatial distribution of stable isotopes in soil water is the result of the combined effect of precipitation isotopes and the natural environment. It is also an important part of the interaction of different water bodies in the land-surface process simulation. Due to the limitations of the positioning monitoring in reflecting the spatial characteristics of large-scale soil water isotopes, GCM (General Circulation Models) is helpful for understanding the spatial pattern of changes in isotope composition of soil water. In this paper, the spatio-temporal distribution characteristics of δ 18 O soil water and the δ 18 O content in soil surface water were compared with air temperature, precipitation, waterlogging, soil temperature and precipitation by three models of LMDZ (free), LMDZ (nudged) and MIROC (free) δ ~ (18) O relationship between the study. The results show that: (1) δ 18 O in soil water is relatively large in southeastern China, and δ 18 O in soil is relatively small in northeast, northwest and Qinghai - Tibet Plateau, and δ 18 O in Qinghai - Tibet Plateau is the smallest. From the national scale, the variation characteristics of δ 18 O in soil water are in accordance with the variation characteristics of δ 18 O. From 1979 to 2007, the average annual soil water δ 18 O and summer soil water δ ~ 18) O and winter soil water δ ~ (18) O all showed an upward trend. (2) The correlation between δ 18 O in soil water and temperature is good, and the temperature effect appears in middle and high latitudes. The farther away from the ocean, the more significant positive correlation exists. (3) All the three simulation results show that there is a positive correlation between δ 18 O in China and δ 18 O in precipitation, indicating that the supply of soil water in most areas comes from precipitation. The correlation coefficient It is larger in the northwest region and gradually decreases from south to north in the northeast. It appears in the annular distribution in the Qinghai-Tibet Plateau, and the correlation coefficient increases from the inside to the outside.