武汉市第四系浅层地下水环境背景值研究

为查明武汉市第四系浅层地下水环境背景值,以2014年采集的21件浅层地下水样品水质分析数据为依据,利用Grubbs检验法剔除异常数据,采用Shapiro-Wilk检验法进行概率分布类型检验,计算该市地下水中的K~++Na~+、Ca~(2+)、Mg~(2+)、F~-、Cl~-、SO~(2-)_4、HCO~-_3、NH~+_4、TDS和总硬度主要成分的环境背景值。结果表明:研究区地下水主要成分的分布类型以正态分布为主,对数正态分布较少,无偏态分布类型;与20世纪90年代江汉平原东部地区相比,本次计算获得的地下水背景值阳离子中Ca~(2+)相对减少,K~++Na~+、Mg~(2+)均相对增加,但变化幅度较小;除HCO~-_3增加外,其余阴离子均减少,且变化幅度较大。地下水化学成分的变化主要与北部山区岩石风化溶解和地下水径流、氧化还原条件有关。

Study on environmental background levels of Quaternary shallow groundwater in Wuhan City

In order to ascertain the environmental background levels of Quaternary shallow groundwater in Wuhan City, based on water quality analysis of 21 groundwater samples collected in 2014, the authors used Grubbs test to reject abnormal data and Shapiro-Wilk method to examine distribution type, and calculated the environmental background levels of K⁺+Na⁺, Ca²⁺, Mg²⁺, F^-, Cl^-, S$O^{2-}_{4}$, HC$O^{-}_{3}$, N$H^{+}_{4}$, TDS and total water hardness. The results show that the distribution type of the main components of groundwater in the study area is dominated by the normal distribution, and the log normal distribution is rare with no skewness distribution. Compared with the background levels of the 1990s in eastern Jianghan Plain, Ca²⁺ is relatively decreasing, and K⁺, Na⁺and Mg²⁺ are slightly increasing. Except the increased HC$O^{-}_{3}$, the rest of the anions are significantly reduced. The change of chemical components of groundwater is mainly related to the weathering dissolution of rocks in northern mountains and the runoff and redox conditions of the groundwater.