| 英文摘要 |
The “Control and Investigation Project for National Agricultural Land with High Potential for Heavy Metal Contamination” was commissioned by the Taiwan EPA in 2010. The following plans “2nd Control and Investigation Project for National Agricultural Land with High Potential for Heavy Metal Contamination” and “3rd Control and Investigation Project for National Agricultural Land with High Potential for Heavy Metal Contamination” were commissioned in 2012 and 2014, respectively.
The main tasks of this plan are conducted according to the supply unit of agricultural water: select and verify the potential heavy metal contaminants in agricultural lands systematically; develop the control strategy by understanding the national potential heavy metal contaminants in agricultural lands; structure a standard operating procedure for agricultural lands investigation by combining the demands of in-situ investigation and pollution prevention; finally, aggregate and edit the investigation operating manual and the remediation technology manual of heavy metal contamination at agricultural soil. There was extensive pollution being discovered at farmlands in Hemei Township, Changhua County during the operating period. This discovery has prompted the organ of prosecution and investigation to detect the emission bypass the legal pipeline toward the East-west second and third canals, and has successfully recovered the pollution responsibility of 4 factories in approximate 90,000,000 NTD. In the meantime, departments in government have improved the controlling power in multiple ways through the protecting program of agricultural water, industry emission counseling platform, and the control standard of agricultural water mass limitation, etc.
Depends on the performances in the latest 3 period, EPA has continued the plan for the 4th period. The priorities of this plan are as follows: combine the evaluation results in agricultural soil and water, investigate the polluted situation in soil and related environmental medium and conduct the relative analysis, and accelerate the progress to grasp the potential distribution of heavy metal pollutions in farmlands. Finally, make the assessments according to all investigation results in the farmlands to advise the treatment method and the administrative control measurements in the future. The investigation range includes the 22 irrigation units which has been selected in the 3rd period as systematic irrigation units in the farmlands with high potential pollution, and the farmlands with irrigation from the high potentially polluted canal route. There are 2 phase of agricultural soil investigation. The result of the investigation shows that there are approximately 91 hectares of farmland exceeded the Soil Pollution Control Standards. The polluted irrigation water are mainly from 3 guiding canal route: Fan-ya canal drain mainline, Yang-tzu-tso brook drain mainline, and Shih-kou drain branch line.
The data of the categories of contaminants in the polluted farmlands, the concentration of contaminants, the area of clumps, and the cadastre of the investigation area has been aggregated according to the soil investigation. To form the farmland remediation and evaluate the budget for the remediation method, the area has been divided into 2 parts according to the canal route: the range of supporting irrigation in Fan-ya canal drain mainline and Yang-tzu-tso brook drain mainline, and the range of supporting irrigation in Shih-kou drain branch line. These 2 parts include 41.20 hectares and 49.37 hectares of farmland, respectively. It is necessary to conduct detailed investigation of the polluted farmlands before the remediation. As the initial evaluation, there are respectively two parts of farmlands in 36.88 hectares and 36.52 hectares could be removed from the control list by conducting the ploughing method with the collocation of soil replacements. The analysis of the channel sediments and water sampling has also been conducted. There are 34 channels with the signals of entering contaminants in the sediments have been selected, and there are 4 units of water samples with heavy metal contents which exceeded the Irrigation Control Standard has been collected at Hsin-tsun canal and Hsin-fen-pei-tsun canal.
By integrating the investigation result of environmental medium, 19 positions have been suspected to be the source of contamination after the filtering. There are 2, 9, 2, and 6 positions has been suspected to be the source of contamination in the main irrigation canal route Fan-ya canal drain mainline, Yang-tzu-tso brook drain mainline, An-dong second drain branch line, and Shih-kou drain branch line, respectively. Total 125 plants are suspected as targets of pollution source, 32 plants among them are being controlled as pollution sources by using raw materials which related to the contamination of environmental medium.
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