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通过珠江三角洲地区两千余组地下水样的pH值现场测试,发现水体酸化是该区地下水环境最为突出的问题之一。偏酸性地下水的分布范围占全区76.3%。该区地下水pH值的分布具有明显的区域性特征。丘陵台地区以偏酸性地下水为主,pH值集中在5.6～6.4;三角洲平原区地下水普遍呈中性,pH值主要介于6.4～7.2。丰、枯水期地下水pH值变幅不大,受酸雨影响,丰水期略有降低。该地区影响地下水pH值的主要因素为酸雨、包气带介质、河流及海水潮汐。丘陵区酸雨入渗强度大、包气带的缓冲能力低,对地下水pH值偏低起了主要作用;平原区粘土层厚,酸雨入渗强度减弱,而河流与地下水交换频繁,加上咸潮与海水入侵的影响,共同导致了地下水pH值升高。
Through the on-site pH value tests of more than 2000 groups of groundwater samples in the Pearl River Delta region, it was found that acidification of the water body is one of the most prominent problems in the groundwater environment in this area. Partial distribution of acidic groundwater accounted for 76.3% of the region. The groundwater pH distribution in this area has obvious regional characteristics. Hilly and trough areas are mainly acidic and groundwater. The pH value is concentrated in the range of 5.6-6.4. The groundwater in the delta plain is generally neutral and the pH value is mainly between 6.4 and 7.2. Feng, dry water pH value range is not large, affected by acid rain, a slight decline in wet season. The main factors influencing the pH of groundwater in this area are acid rain, entrained media, rivers and sea tides. The acid rain infiltration intensity in hilly area is large, and the buffer capacity of aeration zone is low, which plays a major role in the low pH value of groundwater. The thickness of clay layer in the plain area is weakened by acid rain infiltration, while the exchange between river and groundwater is frequent. And the impact of seawater intrusion, together led to an increase in groundwater pH.