摘要
根据2000年8～9月雨季和2001年3～4月旱季在黄河18条断面上河水的同位素测试结果,分析了黄河水δ18O、δD和3H浓度的沿程变化特征。研究结果发现,从黄河源头至入海口,黄河水具有稳定同位素比率逐渐增大而3H浓度逐渐下降的趋势;外来水体的混合作用、蒸发作用以及人类活动对黄河水的同位素具有明显的影响。黄河源头地区和中游地区是黄河两个主要的产流区,河水同位素的变化是不同径流来源对河水补给的良好标志。兰州以上黄河源头地区河水的δ18O、δD的季节性变化与雨水相反,地下水对河水的补给贡献旱季大于雨季。晋陕峡谷北段雨季δ18O相对较低的岩溶水和当地雨水对河川径流有明显的补给,而旱季3H浓度相对较低的岩溶水对河川径流有一定的补给;吴堡-潼关段雨季和旱季均有同位素比率相对较高的地表支流(如汾河、渭河)的加入。河水水面蒸发作用对兰州-包头段和黄河下游段旱季河水的δ18O具有明显的影响,而对这些河段雨季河水的同位素影响较小,灌溉回归水的蒸发可能是影响这些地段河水同位素组成的主要因素。
Oxygen and hydrogen isotopes as well as 3H concentration are analyzed for water samples in the 18 sections of the Yellow River in rainy season (from August to September, 2000) and dry season (from March to April, 2001). From the river source to the estuary, the ratios of the H and O isotopes are increasing and 3H concentrations are decreasing progressively. The main factors affecting the isotopes in the river water are the mixing of foreign water bodies, evaporation and human activities. The river source and the middle reaches are the two main areas where the river runoff is mostly produced. The changes of the isotopes in the river water could be served as the good indicators of the recharge of different foreign water to the Yellow River. In the river source above Lanzhou, the seasonal variation of δ 18O and δ D in river water is different from that in precipitation. The percentage of groundwater contribution to river in dry season is larger than that in rainy season. In the northern segment of the Jinshan gorge, the river is recharged by karst water and local precipitation with low δ 18O in rainy season, and the river by the karst water with low tritium concentration in dry season. In the segment between Wubu and Tongguan, the Yellow river is recharged by the tributaries with high isotope ratios both in rainy season and dry season. In the river segment between Lanzhou and Baotou and in the lower reaches, the evaporation from the river water surface and irrigation return water has a great effect on the stable isotope ratios in dry season and limited in rainy season.
出处
《地球化学》
CAS
CSCD
北大核心
2003年第4期349-357,共9页
Geochimica
基金
国家重点基础研究发展规划项目(G1999043606)
英国皇家协会研究项目(Q778)
