The time limitation on enforcing the project of "The improvement, supervision, and verification works of 110 control sites of farmland heavy metal pollution in Changhua County" is still within the deadline for recovering from polluters. If we could clarify accountability, the results can be used as evidence for the claim. Therefore, the major works of this project is to collect and analyze the environmental information on farmland pollution, and then to determine the association between irrigation systems and farmland pollution.
Checking the 108 sites of the project of "The improvement, supervision, and verification works of 110 control sites of farmland heavy metal pollution in Changhua County" was to summarize time and space information, add the site investigation data, and cross-compare with previous studies. The results showed that there was a high correlation between contaminated farmland soil and sediment. The proportion of the number of related farmlands was 91.3% and the area was 17.71 hectares, which occupied 68.3% of the total area (25.93 ha). For the irrigation sediments and water, the proportion of the number of related farmlands was 46.2% and the area was 8.1 hectares, which occupied 31.2% of the total area. For the contaminated farmland soil and irrigation water, the proportion of the number of related farmlands was 42.3% and the area was 7.27 hectares, which occupied 28.1% of the total area. It can be seen from the above results that there was a correlation between contaminated farmland soil, irrigation water, and sediments.
Additionally, use of field portable X-ray fluorescence (XRF) was to determine the contents of heavy metals in irrigation sediments (307 samples). The finding that the sediments of Changhua City, Hemei Town, and Lukang Town still have high levels of heavy metals. The range of chromium levels was between 24 and 14,561 mg kg-1; the range of copper levels were between 24 and 3,837 mg kg-1; the range of nickel levels was between 12 and 1,358 mg kg-1; the range of zinc levels was between 95 and 62,300 mg kg-1. Therefore, the existence of heavy metals in sediments may enter into the farmland to cause soil pollution with any events.