Abstract

Industrialization and urban expansion can result in the contamination of shallow groundwater by micro-organics (MO) in the Pearl River Delta (PRD), China. This study provides a regional scale assessment of MO contaminants in shallow groundwater in the PRD, investigating the occurrence and distribution of different compound groups, highlighting the relationship between MOs and aquifers, and between MOs and land-use. The main influence of the vadose zone and regional socioeconomic development on each relationship is also analyzed. Twenty-one compounds were detected, with naphthalene, acetophenone, 2-methylnaphthalene and chloroform recording the highest frequencies (1.4–3.1%), 2-methylphenol (328 μg/L), 1,3,5-trimethylbenzene (59 μg/L) and 2,4-dimethylphenol (53.4 μg/L) recorded the highest concentrations. Due to differences in lithology and thickness of the vadose zone over different aquifer groups, notable differences in MOs were recorded between aquifer groups. Twenty-one compounds were also detected with the highest concentrations in Granular aquifers; Karst aquifers recorded the lowest concentration and fewest number of compounds. Different land-use types have also resulted in notable differences in MO contamination, particularly for natural land-use types and urban-industrial types. Natural land recorded both the smallest number of compounds and the lowest concentrations; urban and industrial land-use type had 14 compounds not recorded in other land-use types. Principal component analysis results indicated that urbanization and industrialization in the PRD region were the main driving mechanisms of groundwater MO contamination (via discharges of untreated wastewater). This finding was also verified by the strong positive relationships between waste water levels, discharge volume and, chloride concentrations and MO of the shallow groundwater in the PRD.

摘要

工业化和城市扩张可能会导致珠江三角洲（PRD）中的微生物（MO）污染浅层地下水。这项研究提供了珠三角浅层地下水中MO污染物的区域规模评估，调查了不同化合物组的发生和分布，突出了MOs与含水层之间以及MOs与土地利用之间的关系。还分析了渗流带和区域社会经济发展对每种关系的主要影响。检出二十一种化合物，其中萘，苯乙酮，2-甲基萘和氯仿记录的最高频率（1.4-3.1％），2-甲基苯酚（328μg/ L），1,3,5-三甲基苯（59μg/ L） ）和2,4-二甲基苯酚（53.4μg/ L）记录到最高浓度。由于不同含水层组之间的岩性和渗流带厚度的差异，在含水层组之间记录了MO的显着差异。在颗粒含水层中还检测到了二十一种化合物，其浓度最高。岩溶含水层的浓度最低，化合物数量最少。不同的土地利用类型还导致MO污染的显着差异，特别是自然土地利用类型和城市工业类型。天然土地记录的化合物数量最少，浓度最低。城市和工业用地类型有14种化合物未记录在其他用地类型中。主成分分析结果表明，珠三角地区的城市化和工业化是地下水MO污染（通过未经处理的废水排放）的主要驱动机制。珠三角地区浅层地下水的废水水平，排放量，氯化物浓度和MO之间的强正相关也证实了这一发现。