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Investigation Program for Pollution of Agricultural Land in Dong-xi-2nd ditches & Dong-xi-3rd ditche

The “2nd Control and Investigation Project for National Agricultural Land with High Potential for Heavy Metal Contamination,” commissioned by the Taiwan EPA in 2013, investigated the Jiali line and Tieshan line irrigation areas. These areas were selected from irrigation units in the East-West second and third irrigation system canals. This investigation detected 40.0 hectares of farmland contaminated with copper (Cu), zinc (Zn), nickel (Ni), and chromium (Cr). The specific contamination identified was related to the metal surface treatment industries, and there was widespread public concern about this event. In order to identify the distribution of contamination among farmland irrigated by the second and third East-west second and third canals, EPA carried out its “Investigation of Contaminated Farmlands in Changhua East-West Second and Third Canals Irrigation System”. The focus of this investigation was 9 irrigation areas in the East-West Second and Third canals irrigation system, and the area of the investigation region was 1,696.8 hectares. This project emphasized investigating the soil contamination of farmland and analyzing the spatial correlation between contaminated farmlands and heavy metal pollution sources. The investigation of contaminants in farmlands of 9 irrigation areas was implemented in two phases. In order to accelerate the efficiency of the environmental medium investigation and the supply of environmental information that the authority directed, geographic information maps and data from the “National farmland pollution management system” were continuously updated. Furthermore, this project also applied the supplementary investigation instrument which was developed by EPA for on-site investigations, and practical feedback was offered. According to results of the two-phase soil investigation, there were exceedances. The 1st phase collected 320 soil samples, and the heavy metal content of 89 soil samples was at levels probably exceeding soil pollution regulation standards. In the 2nd phase, 1705 soil samples were collected in total and 498 soil samples exhibited exceedance of the soil pollution regulatory standards (29.2% of samples were polluted, representing 100.2 hectares). The contaminants identified were Cu, Zn, Ni, and Cr. In addition, 100 sediment samples, and 20 water samples of irrigation ditches were collected. The results from sediment samples showed the composite contamination, including Cu, Zn, Ni, and Cr. The heavy metal content of water samples was consistent with the heavy metal content of contaminated farmland soil. Based on the investigation result of environmental media and the distribution of potential pollution sources, the register of suspected pollution sources was completed, and provided to relevant government units.
Pollution of Agricultural Land;heavy metal;Irrigation;Dong-xi-2nd ditches & Dong-xi-3rd ditches