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Nationalwide Control and Investigation Program of Heavy Metal Polluted Agricultural Land.(3)

The “Control and Investigation Project for National Agricultural Land with High Potential of Heavy Metal” (abbreviated as Control and Investigation Project) commissioned by the Taiwan EPA in 2010 conducted a systematic assessment and investigation of agricultural lands with a high potential for heavy metal pollution, with irrigation areas as the unit of examination. In 2012, the 2nd Control and Investigation Project continuously revised the assessment system and developed control strategies for identifying agricultural lands with a high potential heavy metal pollution throughout the country. It combined actual survey practices with the need for pollution prevention, establishing standard operation processes for the investigation of pollution on agricultural lands. Based on the results of these two projects, the Taiwan EPA implemented the 3rd Control and Investigation Project which emphasized the regulation of agricultural lands with a high potential for cadmium (Cd) contamination and prioritized the food safety problem caused by rice with high Cd content. In addition, it evaluated national agricultural lands irrigated from canals with a high potential for pollution. In order to improve administrative management and increase the efficiency of the decision making, and update in accordance with the “National farmland pollution management system,” it used farmland survey tools on other projects and added the function of managing contaminated agricultural lands. Consequently, it took technology, policies, regulations, and administration into consideration, and outlined a complete and exhaustive strategy for the prevention of pollution of agricultural lands. The investigation of contaminants in agricultural lands was implemented in two phases. In the eight irrigation areas in Changhua and Taichung, heavy metal could exist in 102 out of 316 soil samples in the 1st phase. In the 2nd phase, 989 soil samples were collected in total and 235 soil samples exhibited exceedance of the soil contaminant regulatory standards (23.8% of samples were polluted, representing 42.4 hectares). The contaminants identified were copper (Cu), zinc (Zn), nickel (Ni), and chromium (Cr). 50 sediment samples, 22 water samples of irrigation ditches, and 28 groundwater samples were collected. According to results of the surveys mentioned above, the Cu concentration of 50 sediment samples and one irrigation ditch water sample and the arsenic (As) concentration of one groundwater sample exceeded the regulatory standards. In addition, the project undertook an investigation of twenty-seven agricultural land irrigation areas in Taoyuan and Changhua. These parcels were irrigated by canals with a high potential for pollution. In the 1st phase, heavy metal could exist in 143 out of 633 samples in Taoyuan and 95 out of 606 samples in Changhua. Based on the 1st phase investigation results, the scope of agricultural lands with a high potential for heavy metal pollution was predicted using the Kriging-method. A cadastre of polluted agricultural lands was used as a reference for undertaking the investigation.
Pollution screening process, High potential pollution agricultural land, Heavy metals of soil