CAJ | 학술논문

为研究华北平原衡水地区水体蒸发氢氧同位素分馏特征, 采集不同盐度的深层地下淡水( TDS 为0. 61g/L)和浅层地下咸水( TDS为7. 97g/L) , 现场开展室外器皿蒸发实验, 获得了当地气象条件下氢氧同位素分馏参数. 实验结果显示, 淡水及咸水剩余表层水δ18 O与剩余水比率f呈指数关系, 与瑞利分馏模拟结果一致, δD和δ18 O蒸发线斜率分别为4. 78和4. 69. 整个蒸发过程中, 淡水及咸水氢氧同位素值增量ΔδD分别为Δδ18 O的4. 82倍和4. 76倍;剩余表层水相对于初始水δD和δ18 O的变化量与累积蒸发量之比, 淡水分别为2. 68‰/cm和0. 56‰/cm, 咸水分别为2. 78‰/cm和0. 61‰/cm; 而在不同的蒸发时段, 剩余表层水δD和δ18 O的变化量与蒸发量无明显相关性. 受水分子扩散的影响, 蒸发皿中氢氧同位素分馏在垂线上分层微弱. 由于水体盐度较低, 在当地气候条件下进行自由蒸发时, 氢氧同位素分馏的盐效应可以忽略.
위연구화북평원형수지구수체증발경양동위소분류특정, 채집불동염도적심층지하담수( TDS 위0. 61g/L)화천층지하함수( TDS위7. 97g/L) , 현장개전실외기명증발실험, 획득료당지기상조건하경양동위소분류삼수. 실험결과현시, 담수급함수잉여표층수δ18 O여잉여수비솔f정지수관계, 여서리분류모의결과일치, δD화δ18 O증발선사솔분별위4. 78화4. 69. 정개증발과정중, 담수급함수경양동위소치증량ΔδD분별위Δδ18 O적4. 82배화4. 76배;잉여표층수상대우초시수δD화δ18 O적변화량여루적증발량지비, 담수분별위2. 68‰/cm화0. 56‰/cm, 함수분별위2. 78‰/cm화0. 61‰/cm; 이재불동적증발시단, 잉여표층수δD화δ18 O적변화량여증발량무명현상관성. 수수분자확산적영향, 증발명중경양동위소분류재수선상분층미약. 유우수체염도교저, 재당지기후조건하진행자유증발시, 경양동위소분류적염효응가이홀략.
To study the characteristics of fractionation of hydrogen and oxygen isotopes in evaporating water in Heng-shui, a typical region of the North China Plain, two sets of outdoor water evaporation experiments with different salini-ties were conducted under local meteorological conditions. Water was collected from deep fresh water ( TDS=0. 61 g/L) and shallow saline water ( TDS=7. 97g/L) , respectively. The experimental results showed an exponential relationship between δD and δ18 O in residual water and f ( the volume ratio between the residual water and the initial water ) , which was in agreement with Rayleigh fractionation model results. The slopes betweenδD andδ18 O in the residual sur-face water were 4. 78 and 4. 69 for the fresh water and saline water, respectively. It was also shown that the average degrees of enrichment of the hydrogen isotope D were 4. 82 and 4. 76 times those of the oxygen isotope18 O in the fresh water and saline water, respectively. The ratios between the δD and δ18 O variations of the residual surface water and the evaporation were 2. 68‰/cm and 0. 56‰/cm, respectively, for the fresh water; and were 2. 78‰/cm and 0. 61‰/cm for the saline water during the experiment period. Nevertheless, the ratios at different evaporating times had no significant correlations with each other. Isotopic statification was rarely observed in different water layers due to the diffusion effect of water molecules. Moreover, the salt effect on the stable isotopic fractionation during the pan e-vaporation experiment under the typical climatic conditions was negligible, probably due to the low salt concentration in the saline water.