ISSN 1000-3665 CN 11-2202/P

    北京市平原区地下水铁锰分布特征及成因分析

    Distribution characteristics and origin analysis of iron and manganese in groundwater in Beijing Plain Area

    • 摘要: 地下水是北京市供水的重要组成部分,地下水中铁、锰超标会限制水资源的开发利用。为了查明北京市平原区高铁、锰地下水的分布与形成原因,以平原区第四系地下水和沉积物为研究对象,基于X荧光光谱、铁、锰分步提取技术,利用地学数理统计、GIS空间特征等分析方法,探讨地下水中铁、锰的空间分布、地球化学特征及来源。结果表明:(1)研究区域地下水中铁的质量浓度范围为0.02~26.70 mg/L,均值为0.76 mg/L;锰的质量浓度范围为0.01~5.24 mg/L,均值为0.21 mg/L。(2)地下水中铁、锰浓度分布规律基本吻合,总体上呈现出沿着地下水流向(自西北向东南)浓度逐渐升高、随采样深度增加浓度逐渐降低的趋势。(3)典型区域沉积物中铁的质量比范围为925152184 mg/kg,均值为19896 mg/kg;锰的质量比范围为118~7260 mg/kg,均值为503 mg/kg,沉积物中铁、锰以残余态为主,分别占总量的92.3%和86.6%。(4)尽管沉积物中铁、锰质量比没有表现出与地下水中铁、锰浓度相似的分布规律,但地下水铁、锰高值区内两个钻孔中活性组分铁占比与地下水中铁浓度呈正相关关系(R=0.66,P>0.05)、活性组分锰与地下水中锰浓度呈显著的正相关关系(R=0.84,P<0.05),可认为区域地下水中铁、锰的富集与沉积物中活性组分铁、锰有关,同时受缓慢的地下水径流速度、较高的黏土比重等水文地质条件,以及还原环境、酸碱度等因素的影响,人类活动不是造成地下水中铁、锰超标的主导因素。研究结果可为北京市地下水资源开发和管理提供科学依据。

       

      Abstract: Groundwater is an important part of Beijing's water supply, excessive ferric and manganese in groundwater will limit the development and utilization of water resources. The spatial distribution, geochemical characteristics, and sources of ferric and manganese in groundwater were analyzed based on X-ray fluorescence spectrometry, iron and manganese step extraction method, geological statistical analysis, and GIS spatial feature analysis. Results show that the iron concentration in groundwater in the study area ranged from 0.02 to 26.7 mg/L, with an average of 0.76 mg/L, and the manganese concentration ranged from 0.01 to 5.24 mg/L, with an average of 0.21 mg/L. The distributions of iron and manganese in groundwater were basically consistent, showing a trend of gradually increasing along the groundwater flow direction (from northwest to southeast) and gradually decreasing with the increase of sampling depth. The mass ratio of iron in the deposits ranged from 9251 to 52184 mg/kg, with an average of 19896 mg/kg, while the mass ratio of manganese ranged from 118 to 7260 mg/kg, with an average of 503 mg/kg. The mass ratios of iron and manganese in the sediments in the whole city did not show a distribution pattern similar to that in groundwater. However, there were positive correlations between the proportion of active component iron and the iron in groundwater (R=0.66, P>0.05), and between the content of active component manganese and the manganese concentration in groundwater (R=0.84, P<0.05). It can be considered that the enrichments of iron and manganese in groundwater in the study area are related to the active components of iron and manganese in sediments. They are affected by hydrogeological conditions such as slow groundwater runoff rate, high clay specific gravity, reduction environment, and pH. Human activities are not the main factors that cause excessive iron and manganese in groundwater. This study provides valuable guidance for the local government in improving the management and utilization of groundwater resources.

       

    /

    返回文章
    返回