云南鹤庆盆地岩溶地下水稀土元素地球化学特征

Rare Earth Element Geochemical Characteristics of Karst Groundwater in Heqing Basin,Yunnan Province

为揭示云南鹤庆盆地岩溶地下水中稀土元素地球化学特征,对该盆地内主要岩溶泉水和地下河水样进行了水化学常规指标测试和稀土元素测试,分析研究了该地区地下水中稀土元素质量浓度、配分模式以及分异特征和影响因素。结果表明:由于含水岩组的截然不同,造成盆地东部岩溶地下水比西部岩溶地下水ΣREE质量浓度高,该地区岩溶地下水中ΣREE浓度与Eh,HCO_(3)^(-),Ca^(2+)有负相关性,与pH,DO,Fe和Mn有较好的正相关关系,高含量HCO_(3)^(-)和Ca^(2+)在一定程度上制约了REE在水中的溶解,铁锰氧化物矿物的还原性溶解是REE进入地下水的主要途径。地下水中LREE有富集、有亏损,还有部分既不富集也不亏损,盆地东部地区地下水中HREE富集程度远远大于西部地区地下水。该地区岩溶地下水表现出明显的Ce负异常和Eu正异常,可能与含水岩组岩性和还原环境有关,同时高Ca^(2+)和HCO_(3)^(-)的环境中,Eu^(2+)更容易被释放出来进入地下水中。在地下河管道中,地下水经过长距离的地下径流后,地下河出口∑REE质量浓度高于岩溶泉水,且与入口相比,出口地下水中轻稀土富集和Eu正异常有所增强,Ce负异常程度减少。

In order to reveal the geochemical characteristics of rare earth elements in Karst groundwater in Heqing basin,the conventional indexes and REE tests of main Karst springs and groundwater samples in the basin were conducted.The quality concentration,distribution mode,differentiation characteristics and influencing factors of rare earth elements in groundwater in this area were analyzed and studied.The results showed that the quality concentration of the total rare earth element in the eastern part of the basin is higher than that of western Karst groundwater due to the different water bearing rock groups.The concentration of the total rare earth element in Karst groundwater in this area is negatively correlated with Eh,HCO_(3)^(-),Ca^(2+),and has a good positive correlation with pH,dissolved oxygen,Fe and Mn.The high content of HCO_(3)^(-) and Ca^(2+) restricts the dissolution of REE in water,and the iron manganese content is negative correlation with pH,DO,Fe and Mn.The reductive dissolution of oxide minerals is the main way for REE to enter groundwater.LREE in groundwater is rich and or some has losses,and some of them are neither enriched nor lost.The concentration of HREE in the groundwater in the eastern part of the basin is much higher than that in the western region.The Karst groundwater in this area shows obvious negative Ce anomaly and positive Eu anomaly,which may be related to the lithology and reduction environment of water bearing rock formation.At the same time,Eu^(2+) is more likely to be released into groundwater in the environment with high Ca^(2+) and HCO_(3)^(-).In the underground river pipeline,the mass concentration of ∑REE at the outlet of the underground river is higher than that of the Karst spring after a long distance of underground runoff.Compared with the inlet,the enrichment of LREE and the positive anomaly of Eu in the outlet groundwater are enhanced,and the negative anomaly of Ce is reduced.Compared with the groundwater in the outlet of Karst spring river,the REE concentration in the outlet of Karst spring river is slightly higher than that in the outlet of Karst spring river.