成都平原典型区地下水污染时空异质性及污染源分析

成都平原地下水是该地区生活、工农业生产用水的重要来源,但由于长期过量使用化肥,以及畜禽养殖、乡镇企业及生活污废水的无组织排放,已对该区地下水环境构成了威胁.本研究选取成都平原某典型城镇农村区进行不同时季地下水水质监测分析,并联合ArcGIS空间分析技术、相关矩阵分析和主成分分析(PCA),以揭示研究区地下水水质时空异质性、污染影响因素、潜在污染源及污染源时季变化规律.结果表明,研究区"三氮"(NO~-_3、NO~-_2、NH~+_4)、铁(Fe)、锰(Mn)、氯离子(Cl~-)、硫酸根离子(SO■)存在不同程度的超标,其中,氨氮(NH~+_4)超标最为突出;地下水中氨氮含量及"三氮"之间的转化主要受土地利用类型、地下水铁锰分布及含水层氧化还原条件的影响.PCA结果显示,农业活动、生活污水和工业排放是造成研究区地下水污染的主要影响因素,从春季到夏季地下水污染源由生活污染为主转向农业污染为主,冬季地下水污染源以生活和工业源为主.ArcGIS空间分析和PCA分析的结合,有助于探讨地下水水质及潜在污染源的时季变化规律,可为地下水环境保护、污染控制和减缓方案制定提供理论依据.

Spatial-temporal heterogeneity and pollution sources of groundwater pollution in typical area of Chengdu Plain

Groundwater in Chengdu Plain is an important water resource for domestic, industrial and agricultural uses. Application of excessive chemical fertilizers, livestock and poultry manure, wastewater discharge have posed a threat to the groundwater environment. In this study, groundwater quality monitoring and analysis were conducted in a typical urban and rural area of Chengdu Plain in different seasons. Spatial and seasonal variations in groundwater quality, influencing factors, potential pollution sources and seasonal variation of pollution sources were revealed by combining ArcGIS spatial analysis technology with correlation matrix analysis and principal component analysis (PCA). The results show that groundwater NO₃^-, NO₂^-, NH₄⁺, Fe, Mn, Cl^-, SO₄^2- exceed the standards in varying degrees in the study area, especially the exceeding rate of NH₄⁺ was extremely high. Groundwater NH₄⁺ and the transformation between different nitrogen components are mainly affected by land use types, presence of Fe and Mn in groundwater, and redox conditions in aquifers. PCA results show that agricultural activities, domestic sewage and industrial discharge are potential sources of groundwater pollution in the study area. From spring to summer seasons, the main groundwater pollution source shifted from domestic discharge to agricultural inputs, while domestic and industrial discharges were the main contribution of groundwater pollution sources in winter season. The combination of ArcGIS spatial analysis and PCA analysis is helpful to explore the seasonal variation of groundwater quality and potential pollution sources, providing scientific support for groundwater environmental protection, pollution control and mitigation.