| 摘要: | 採礦業對於泰國之經濟發展及改善礦區附近社區居民的就業情況，固然具有一定的貢獻，但是，採礦廢水與廢礦碴未適當處理與處置，長久以來已造成鄰近居民之健康風險及環境衝擊問題。本研究係探討鉛礦場廢棄封閉後，未有適當污染防治措施與污染監控，對於鄰近地區民眾的健康及環境所產生之負面影響，並以泰國甘差那布里府之克里汐灣 (Klithy Creek of Kanchanaburi) 的一座鉛礦場為例 (以下簡稱KC礦場) 進行研究。
廢棄礦場的污染源主要為所排放廢水中的污染物及棄置現場之廢礦，因沉積於水體底泥及土壤中所造成之環境污染。根據泰國污染管控部(Pollution Control Department) 於2015年，對於KC礦場所造成的水質、溪流底泥、魚肉與稻作等的污染監測數據，所推估該礦場鄰近居民的人體每日鉛攝取量 (average daily dose of lead，以下簡稱「鉛-ADD」) 資料，本研究發現，居住於克里汐灣村上游居民的鉛-ADD量為：小孩 6.5892 微克/公斤(體重)/天 (g/kg/day)，成人3.9383 微克/公斤/天；而下游克里汐灣村民的鉛-ADD量為：小孩 5.7360微克/公斤/天，成人為 3.5643微克/公斤/天。上述村民的每日鉛攝取量，已明顯超過「聯合國糧農組織與世界衛生組織的食品添加物聯合專家委員會（Joint FAO/WHO Expert Committee on Food Additives, JECFA）」所建議之「容許每日鉛攝取量 (Tolerable Daily Intake，TDI) 標準。本研究進一步探討克里汐灣村民受到該廢礦場的鉛污染途徑，最顯著的污染傳輸途徑是經由間接攝取 (於灣流中游泳及汲取溪水洗澡而不經意的攝進已被污染的水) 約佔69.06%，其次為由攝取當地含鉛的魚肉，約佔20.5%，其餘依序為食用污染的稻米，約佔9.2%，以及接觸含鉛微塵的空氣，約佔1.23%。
本研究為探討受到KC鉛礦場污染場址的復育策略，採用屬於多目標評估方法之層級分析法 (Analytic Hierarchy Process，AHP)，經由彙集本研究所遴選的各方面專家，包括政府環境部門人員、環境工程師及當地村民等的專家意見，再藉由評量表所做成之各層級成對比較矩陣等量化之衡量資料，作為場址復育策略之決策評估依據。本研究的AHP評估結果顯示，最佳的場址復育策略為克里汐灣的底泥浚渫，此外，根據環境工程師的專家意見，自然環境復育方面的監測 (Monitoring Natiral Recovering) 亦應進行。
;In Thailand, the industrial mining contributes to the economic development of the country through foreign exchange earnings, employment and improved living standard of Thai people nearby the mining area. However, the processing water and disposal of mining tailings during its operation have become a long-term potential health and environmental risk. This study assessed and examined the impacts of closed lead-mining field on resident health and the surrounding environment in Thailand. A case study of the closed and abandoned lead mine located in the Klithy Creek of Kanchanaburi (here in after referred to as KC-mine) in the nation was examined.
Pollution from closed mines normally comes from two main sources: the discharge of wastewater during mining workings and the wasted materials spread on the surface of soil. During the operation, the processing water and tails of lead-mine was drained and discharged from working areas, that resulted in increasing the levels of lead in surrounding water bodies and soils. According to the estimation data of Pollution Control Department of Thailand in 2015 for the average diary dose (ADD) of lead based on the environmental pollution monitoring data of surface water, creek sediment, air, fish (muscle), rice, and vegetables in neighboring area of KC-mine, this study found that, in upstream residents, the lead-ADD of children is 6.5892 μg/kg/day and that of the adult is 3.9383 μg/kg/day. In downstream residents, the lead-ADD of children is 5.7360 μg/kg/day and that of adult is 3.5643 μg/kg/day. The lead-ADD of residents whether living in upstream or downstream areas are obviously higher than the tolerable daily intake (TDI) of potential impact to human health, i.e., TDI of children and adult are 3.517, which were provided by Joint FAO/WHO Expert Committee on Food Additives (JECFA). In addition, the most of pathway of contaminant distribution from high to low is the indirect water intake when swimming in the creek and bathing with the creek water (69.06%), that from ingestion of fish food (20.51%), ingestion of rice (9.20%), and from inhalation of air (1.23%) in sequence.
In view of the effort in restoration of contaminated KC-mining field by Analytic Hierarchy Process (AHP) basing on the opinions of authorized government personnel, environmental engineer, and residents living in Klithy Creek of Kanchanaburi, application of pollution control engineering and government intervention measures should be carried out.
The result through AHP process of this study reveals that the removal of sediments by dredging for remediation was most preferred by all expert groups because this remediation method requires less time to achieve efficient contaminant cleanup, and also around this site has suitable disposal sites to reduces transport-related operating costs. Nevertheless, the environmental engineering also prefers the monitoring natural recovering (MNR) due to this area is the lead potential site and highly uncertain of contaminated sediment lead to uncertainty of remediation dredging. It likely to adversely impact water quality and engineering controls may not be effective in protecting water quality which this is a main issue that can affect to health of residents. Furthermore, based on the AHP results and limitation, I preferred the environmental dredging method for the area of the high potential health risk. The vertical barriers wall was proposed for the area of the high potential for sediment mobility but low potential human health, and also continuously monitor the spread of pollution as well as the environmental rehabilitation policy should be carried out for the lead-contaminating area to ensure that the effects of resident health and environmental impact in the KC-mining area can be reduced to the minimum. |
