摘要
广东省英德市白沙镇花岗岩风化壳地下水主要属于HCO3-Ca·Na型。水样的pH值在4.3～6.6之间。与世界其他花岗岩地区地下水相比,白沙地区花岗岩风化壳地下水的稀土元素(REE)总浓度偏高,在1.1～114μg/L之间,变化范围较大。地下水中的REE浓度与水的pH值呈弱的负相关关系,并且受母岩风化程度的影响。由于pH值、氧化还原状态及水中主要离子组成的差异,使得可溶态REE在水中的赋存状态存在差异。地下水与母岩、风化壳REE的PAAS标准化分布模式基本相似,呈LREE富集型,母岩中无Ce异常,而水样中有Ce负异常,表明Ce在水岩作用过程中发生了明显的分异。
Rare earth element (REE) concentrations are measured in 25 well water samples, 1 reservoir water sample and 4 stream water samples collected from Fogang granitoid weathering crust in Baisha, Yingde city, Guangdong Province. The pH values of the groundwaters from the granitoid weathering crust range from 4.3 to 6.6. Ca and Na are the dominant cations of the groundwaters, and HCO3 is the predominant anion. REE concentrations in Baisha groundwaters vary between 1.1 and 114 μ g/L, which are higher than those in many other groundwaters from granites in the world. The concentrations of REEs in the groundwaters with pH < 5 are generally high. A weak negative correlation could be seen between the pHs and the REE concentrations of the groundwaters. And the REE concentrations of the groundwaters are controlled by the weathering degree of the primary rocks. The aqueous speciation of the REEs in groundwaters is affected by pH, Eh and major ions. On the PAAS normalized patterns, the primary granites and the granitoid weathering crust are LREE enriched with no Ce anomaly, and the groundwaters are LREE enriched with a negative Ce anomaly, indicating Ce fractionation during water rock interaction.
出处
《地球化学》
CAS
CSCD
北大核心
2003年第4期335-342,共8页
Geochimica
基金
国家杰出青年科学基金(49725309)
