| The objective of this study is Nanhongmen reclaimed water irrigated area ofDaxing District in Beijing, along the surface water-soil-groundwater system, throughthe arrangement of monitoring network, and the monitoring of the reclaimed waterquality, soil pollutant, groundwater quality and water level, this article analyzed andevaluated the recycled water quality, the vertical distribution of soil typical pollutantsand the present distribution of groundwater quality in the study area. It found out thegroundwater environment status and pollution causes in the typical renewable waterirrigation district, analyzed the groundwater pollution situation in a systematic way,evaluated the groundwater pollution degree and trends synthetically, wrote theinvestigation report of the groundwater basic environmental status in typical renewablewater irrigation area, provided a scientific basis for the compilation of groundwaterpollution prevention and control plan, the establishment of the groundwater basicenvironmental information systems in typical reclaimed water irrigation area and theoptimization of groundwater monitoring network. Through this project, initially findout the groundwater basic environmental status in typical Beijing renewable waterirrigation area, basically sort out the sources of pollution, scientifically formulate thecountermeasures of pollution prevention and control, and play an exploration anddemonstration role in groundwater pollution problems caused by the use of recycledwater for irrigation, have strong theoretical and practical significance.Through the renewable water quality monitoring and evaluation, the renewablewater sources in the irrigated area are mainly from the Huangcun and Xiaohongmenwater recycling plants which mainly process urban sewage, recycled water quality isrelatively good, the water quality of the eight monitoring sections meets the irrigationwater quality standards in addition to Caiyu gates,whose salt and sulfide in a singlemonth does not meet the standards(urban wastewater reclamation and reuse irrigationwater quality (GB20922-2007) and irrigation water quality standards (GB5084-2005)).Selected separately from the upstream to downstream of the irrigation area to layout drilling, carried out soil pollutant monitoring, the result showed that, contaminantsaccess to the vadose zone soil stay in a relatively low levels, at the same time as thesoil vadose zone in the study area is composed by the fine-grained sands and sticky particles, the pollutants are difficult to penetrate the vadose zone into the aquifer.Through the layout of the28water quality monitoring wells, respectively usingsingle indicators and composite indicators assessment methods for water qualityevaluation, results show that, for the long-term sewage irrigation in history, the waterquality is poor currently in some of regional study area, accounting for34.2%of thestudy area, mainly in its southeast and southwest. Through the groundwater qualitytrend analysis from2006to2011, yet the impact to irrigation area groundwater qualityis not found, which is caused by irrigation with reclaimed water. Through the analysisof the groundwater level monitoring data, the use of recycled water for irrigation hasreduced the amount of groundwater exploitation in the study area, at the same timecovering to a certain extent on groundwater resources.Variation of GMS (groundwater simulation software) to simulate differentscenarios of groundwater chloride transport. Because the quantity of the irrigationwater is less than the aquifer groundwater water, and groundwater flow velocity isrelatively fast.The effection of irrigation reclaimed water is little to groundwater.The time of reclaimed water for irrigation in study area is short, the adverse effecton groundwater quality yet has not found, but because of the complexity of recycledwater quality, the further strengthen of the groundwater monitoring in the irrigationarea is still required. |
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