Analysis of groundwater contamination due to ammonia and its impact on water supply

河内市地下水受到氨、有机物和砷的污染，但地下水污染的来源和机制尚未完全阐明。本研究以单-(MMA)、二甲基胺（DMA）和MMA/DMAratio为示踪剂，探讨河内市地下水氨和有机物污染的来源和机制。2000年8月、2000年12月和2001年9月采集水样116份，2001年9月采集土芯样61份。在污染地下水中，氨、MMA和DMA的相关性强，表明氨和ma均来源于有机降解。污染地表水的MMA/DMA比值高于地下水。这些结果表明，地表水中甲基丙烯酸甲酯的主要来源是生活污水和鱼饵中蛋白质中甘氨酸的降解，而地下水中甲基丙烯酸甲酯和甲基丙烯酸甲酯的主要来源是三甲胺的降解。作为厌氧TMA分解的副产物，DMA在地下水中积累。这些MMA和DMA在地表水和地下水中富集的不同机制使得这些伯胺和仲胺类物质成为地下水污染的示踪剂成为可能。结合游离化合物的碱度及其质子化类似物的溶剂化行为可以解释的吸附度，即DMA > MMA >氨，我们可以得出结论，MMA/DMA比值可以用于识别地下氨和有机物的原位来源。

Groundwater in Hanoi City is contaminated with ammonia, organic matter, and arsenic, but the source and the mechanisms of groundwater contamination was not yet been fully elucidated. In this study, mono-(MMA), di-methylamines (DMA), and the MMA/DMAratio were used as tracers investigatete source and mechanism of groundwater contamination due to ammonia and organic matter in Hanoi City. Water samples (n=116) were collected in August 2000, December 2000, and September 2001, andadditionally soil core samples (n=61) were collected in September 2001. In the contaminated groundwater, strong correlation between ammonia, MMA and DMA indicated that both ammonia and Mas originated from organic degradation. Contaminated surface waters had higher MMA/DMA ratio than in the groundwaters. These results suggest that the major source of MMA in the surface waters is degradation of glycine in proteins contained in domestic wastewater and fish baits, whereas the major source of DMA and MMA in groundwaters is degradation of tri-methylamine (TMA). As a by-product of anaerobic TMA decomposition, DMA accumulates in groundwaters. These different mechanisms of MMA and DMA enrichment in surface and groundwaters makes it possible to use these primary and secondary amine species as tracers of groundwater contamination. Together with the degree of adsorption, namely DMA > MMA > ammonia, which was explained both by the basicity of the free compounds and the solvation behavior of their protonated analogues, we can conclude that the MMA/DMA ratio can be used to identify in situ sources of ammonia and organic matter in underground.