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广州市作为珠三角地区的政治经济中心,人口数已经超过1 500万,因此,其供水安全问题至关重要。虽然广州市目前供水主要来源于东江、西江和北江,但是水污染等问题使得其供水能力较为脆弱,而地下水作为应急水源,了解其水质及影响因素为重中之重。为了解广州市地下水化学特征概况和土地利用类型对地下水的影响,分别于2014年12月(旱季)和2015年7月(雨季)各采集72个浅层地下水水样,分析水中pH、TDS和主要的七大离子含量;运用GIS的相关技术方法分析水化学性质的时空分布特征,对水化学类型区域进行划分;采用Duncan多重比较法分析土地利用类型对地下水化学特征的影响。结果表明,广州市浅层地下水化学特征季节性差异不显著,但空间上存在较大差异,其中Na~+和Cl~-在空间上的变异性最大。由于广州市东北地区土壤层较薄,对酸雨的缓冲能力较弱,并且作为流域内的主要补给区,其pH值较低,pH总体呈现出东北低西南高的分布趋势;TDS主要受到海水的影响呈现出与pH相似的分布趋势,另外,农耕地覆盖下和脆弱性较高地区的地下水中的TDS含量相对较高。广州市浅层地下水水化学类型以Ca+Mg-HCO_3为主,沿海区域和中心城区由于海水入侵和人类活动的影响导致水化学类型向Na+K-Cl+SO_4型转变。根据差异性分析结果,土地利用方式会对地下水造成一定的影响,但是较为分散的土地利用方式对地下水的影响效果不显著,而由于行政功能划分不同造成的各土地利用方式在不同行政区的比例差异却会对地下水化学性质造成显著的影响。K~+与SO_4~(2-)在浅层地下水中的含量与农耕用地面积存在正相关关系,Na+则主要与城镇用地面积相关,Cl~-同时受农耕用地和城镇用地的影响。
As the political and economic center of the Pearl River Delta Region, Guangzhou has a population of more than 15 million. Therefore, its water supply security is of the utmost importance. Although the current water supply in Guangzhou mainly comes from the Dongjiang, Xijiang and Beijiang rivers, problems such as water pollution make it more vulnerable to water supply. Groundwater, as an emergency source of water, is an important source of water quality and its influencing factors. 72 groundwater samples were collected from December 2014 (dry season) and July 2015 (rainy season) in order to understand the general characteristics of groundwater chemistry and the impact of land use types on groundwater in Guangzhou. The effects of pH, TDS and The main seven major ion content; the use of GIS technology to analyze the spatio-temporal distribution of water chemistry characteristics of the water chemistry type of area division; using Duncan multiple comparison analysis of land use types on the groundwater chemical characteristics. The results showed that the seasonal variation of chemical characteristics of shallow groundwater in Guangzhou was not significant, but there was a big difference in space. Among them, Na ~ + and Cl ~ - had the largest spatial variability. Due to the thinner soil layer in northeastern Guangzhou, the buffering capacity of acid rain is weak, and as the main recharge area in the basin, the pH value is low, and the pH generally shows the distribution trend of low northeastern low southwest; the TDS is mainly affected by seawater The impact shows a trend similar to that of pH. In addition, the TDS content in groundwater covered by agricultural land and in areas with high vulnerability is relatively high. The chemical type of shallow groundwater in Guangzhou is Ca + Mg-HCO_3, and the change of hydrochemistry type to Na + K-Cl + SO_4 type due to seawater intrusion and human activities in the coastal area and central urban area. According to the result of the difference analysis, the land use pattern will exert certain influence on the groundwater, but the effect of the more scattered land use pattern on the groundwater is not significant. However, due to the different administrative functions, the proportion of each land use pattern in different administrative regions is different It will have a significant impact on the chemical properties of groundwater. The content of K ~ + and SO_4 ~ (2-) in shallow groundwater has a positive correlation with the area of agricultural land, Na + is mainly related to urban land area, and Cl ~ - is influenced by both agricultural land and urban land.