The investigation of executing period of this project is from September 3, 2012 through September 2, 2013. The aim of this project was to investigate the agricultural land of five highly pollution potential irrigation groups in Taoyuan district. In addition, it was to govern the possible pollution sources within the target population via the transport pathways between sediments and water quality and to establish the conceptual model of pollution sample district. Up to the final term, planned objective has been fully met. Totally 1671 sets of agricultural land soils have been executed for the investigation. Among the investigation 690 sets have attained the control standard and the polluted area is around 105 ha. The exceeding item of heavy metal is mainly copper (Cu). The spatial distribution of polluted blocks shows that the irrigation group irrigated with district drainage has higher ratio of pollution. The investigation of sediment and irrigation water shows that partial investigated sites have correlated with some specific suspected pollution sources. Additionally, we have judged the hazardous range of each target heavy metal by using geographic statistics. From the consecutive monitoring results of soil, sediment, and water quality, the concluded causes of pollution include: 1) Insufficient water of Taoyuan large aqueduct leads to the agricultural blocks at downstream irrigated with district drainage such as Puhsin and Hsinje brooks and Sankuaitso branch, which has been polluted by heavy metals; 2) Vicinal factories have illegally discharged wastewaters to aqueducts; 3) Though the wastewaters discharged from factories meet the discharged water quality standard, it is more strict than the irrigation water quality standard. This results in the accumulation of heavy metals in agricultural soils via long-term irrigation. According to heavy metal spatial correlation to estimate suspicious pollution sources, we propose to provide Environmental Protection Bureau an inventory as a basis for strengthening inspection and compensation claims. Consecutively, based on the historical inspection records and investigation of pollution sources, the eight factories have discharged wastewaters which do not comply with discharged water quality standard into the irrigation system. We plan to list these factories as reparation-enquiry objects and further plan the warning system to prevent from persistent pollution of agricultural land in the future.

Farmland soil pollution survey, Channel sediment and water quality survey, Suspicious sources