| 英文摘要 |
The agricultural development was considered as a solid foundation for the industrial transformation in the early stage of economic growth in Taiwan. However, with the outbreak of food safety issues caused by soil pollution, the protection for farmlands has been gradually started to be valued.
In view of the fact that the farmland pollution are mainly caused by the pollution in irrigation water source, Taiwan EPA had conducted investigations in the past decades. Until the end of 2017, a total of 1,117 hectares of contaminated farmlands were investigated by EPA, in which 610 hectares have been improved completely and delisted. Improvement works in the remaining pollution sites are expected to be completed within two to four years.
However, there were still 7,574 polluted farmland sites found with heavy metal concentration between the Monitoring Standard and Control Standard, and some of them are located in the irrigation range of the “44 ditches with high pollution potential” evaluated by COA at the end of 2016. This condition might lead to three situations which need proper countermeasures, including the concern for repeat pollution, the heavy metal accumulation in the monitoring farmlands (which have almost exceeded the Monitoring Standard), and the huge budget demand for farmland monitoring works. Therefore, as the management and governance for farmlands, EPA has developed and promoted the pollution investigation and controlling works into pollution prevention and quality protection
Consequently, following the historical soil survey results, the “Management Project for Pollution Prevention in Farmland” is progressed. This project firstly focusing on the development of multi-management and risk grading strategies for farmlands with heavy metal contamination, the establishment for long-term monitoring and precaution procedures which could effectively avoid heavy metal pollution occurs in the farmlands, and the plan for two demonstration zones for pollution precaution in accordance with the ditch routes with high pollution potential. The demonstration zones include the Third Irrigation Group of Nan-wei branch and Liu-cuo ditch in Shi-gou drainage irrigation zone, and Xiao-shin Ditch Irrigation Group in the irrigation zone of Yang-zi-cuo stream drainage main line. Secondly, the implementation of this project includes summarizing the data of heavy metal polluted farmlands in the country, selecting and screening three pollution source assessment zones for the pollution source investigation works. These three pollution source assessment zones include the irrigation group of Da-tu-liao ditch and Chien-cuo-yuan ditch under the jurisdiction of Taichung Irrigation Association, Group of Gong-cuo branch, Hsin ditch, and Hsin-fen ditch under the jurisdiction of Changhua Irrigation Association, and the 2-9 Group under Taoyuan Irrigation Association.
For the risk grading and multi-management for farmlands with heavy metal pollution, this project has searched for the farmlands management strategies in other countries with rice production such as Japan, China, and Korea. After the information collecting and searching process, this project has summarized four suggestions include cross-department implementation for pollution improvement and management, the necessity of production environment improvement to be included in the soil pollution improvement works, the necessity to treat pollutions with different hazard level separately, and the necessity to continue the monitoring process after improvement and rehabilitation.
As the farmlands with systematic feature and continuous accumulation of pollutants, two pollution precaution monitoring zones were selected for the environmental site assessments and soil screening survey. There are three irrigation groups included in the range of the two pollution precaution zones, and the total area is about 612 hectares. The team of this project has collected 200 sets of soil samples and screened with XRF analyzer. After comparing the results with the Control Standard and the Monitoring Standard for food corps farmlands, pollution screening value has increased in 28 sets of samples, and has decreased in 21 sets of samples. In other 151 sets of samples, the pollution screening value showed no significant changes.
As the plan for the risk grading structure of pollution prevention management in farmlands, this project suggests separating all farmlands (about eight hundred thousand hectares) in the whole country into three parts, including forty-one thousand hectares as farmland deterioration prevention zone, eighty thousand hectares as farmland deterioration precaution zone, and six-hundred and eighty thousand hectares as farmland quality protection zone. Pollution prevention suggestions will be discussed based on different features in each zone.
As the pollution source investigation in polluted farmlands with unknown polluter, the team of this project has completed the selection for six pollution source assessment zones and soil screening investigation. The team of this project has collected 300 sets of soil samples and screened with XRF analyzer. After comparing the results with the Control Standard and the Monitoring Standard for food corps farmlands, pollution screening value has increased in 16 sets of samples, and has decreased in 81 sets of samples. In other 203 sets of samples, the pollution screening value showed no significant changes.
There are also automatic machines for water quality monitoring and sampling set in four pollution source assessment zones. The monitoring process has continued for sixty months with sixty sets of samples. Water samples with heavy metal concentration exceeding the Control Standard were from Da-tu-liao ditch, No. 1 water supply of Da-tu-liao ditch, No. 2-1 and 3 water supplys of Chung-Hsing main line in Chien-cuo-yuan ditch, Hsin ditch, and the No.2 drainage ditch connected with No. 2-9 pond. The team of this project has completed the selection and investigation planning in three pollution source assessment zones with the works includes 306 samples for the sediment in the ditches, 744 samples of time-lapse resin capsules for heavy metal monitoring, and 40 samples for characterization investigation.
According to the result, the pollution mainly includes chromium, copper, nickel, lead, or zinc. Based on possible pollution intervention points, four, eight, and four factories as suspicious polluters were defined according to each factory process operation. The plan for polluted farmlands compensation in three zones has been completed, which includes farmlands in Da-li District in Taichung City, Changhua City and He-mei Township in Changhua County, and Lu-kang Township in Changhua County.
After searching and summarizing the management measures for water source and farmlands from each department and association, the team has proposed the management strategies and improvement measures to enhance the soil pollution prevention management for farmlands. Based on the current status of pollution source, delivery, polluted soil and corps management, this project has integrated the promotion process of pollution prevention in farmlands and planned the draft of “Farmland Pollution Prevention Plan”. The team has included the consultation from experts during the implementation to amend the plan, meanwhile, the team has propagate the concept of pollution prevention and got feedback from the resident communication seminar.
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