Study on Soil Water Dynamics on Loess Tableland Based on Stable Hydrogen and Oxygen Isotopes
Based on the stable hydrogen and oxygen isotopic composition of precipitation and soil water in Changwu loess tableland,the characteristics of stable hydrogen and oxygen isotopic composition and soil water migration in the soil profile were studied.The results showed that the values of δD and δ18O in soil water within 0-150 cm varied between (-77.15‰)～(-24.89‰),and (-13.00‰)～(-3.39‰),and the mean and standard deviation were-51.50‰ and 9.09‰,-7.22‰ and 1.45‰,respectively,which the variation range was far less than that in precipitation.The δD and δ18O in soil water fell on the local meteoric water line of Changwu tableland(δD=7.44δ18 O+ 1.69) and the relationship of was the soil water isotope composition were δD=4.495δ18 O-19.05.The slope and intercept were lower than that in precipitation,which indicated obvious isotope fractionation during the precipitation infiltration in the soil.The effect of precipitation on the δD and δ18O contents in shallow layers of soil water was obviously and that was much less in lower layers.The contents of δD and δ18O were largest at 30 cm and decreased rapidly downwards,and that varied little below 100 cm.The contents of δD and δ18O in soil water of lower layers were influenced by that in the upper ones,which indicated that the soil water mixed at different degree with the free water in upper soil layers during infiltration.There was dynamic change of δD and δ18O contents in soil water at 150 cm,which showed that soil water could infiltrate in form of "preferential flow" downward through the existing macropore in the soil.
soil water dynamicsprecipitationsoil waterhydrogen and oxygen isotopeloess tableland
国家科技期刊平台
NSTL
万方数据
维普
