蘭陽平原地下水水溶氣(甲烷)厭氧氧化作用對含水層砷釋出之影響;Effect of in situ anaerobic methane oxidation on the mobilization of arsenic

NCUIR > Engineering College > Graduate Institute of Environmental Engineering > Electronic Thesis & Dissertation > Item 987654321/93729

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/93729

Title:	蘭陽平原地下水水溶氣(甲烷)厭氧氧化作用對含水層砷釋出之影響;Effect of in situ anaerobic methane oxidation on the mobilization of arsenic
Authors:	柏貫中;Pao, Kuan Chung
Contributors:	環境工程研究所
Keywords:	砷;地下水;蘭陽平原;水溶氣;甲烷厭氧氧化;arsenic;groundwater;Lanyang plain;methane;anaerobic oxidation of methane
Date:	2022-11-15
Issue Date:	2024-09-19 17:32:44 (UTC+8)
Publisher:	國立中央大學
Abstract:	地下水是全世界重要的水資源，含高濃度砷的地下水對仰賴此水資源的民眾造成莫大的健康威脅，為全球公共衛生的重大議題。台灣蘭陽平原地下水具有高濃度的砷，20 % 的水井砷濃度超過 WHO 所訂定的地下水砷濃度建議值 10 ppb，當地居民也非常仰賴地下水資源，因此含砷地下水為居民的潛在健康危害。宜蘭縣冬山鄉武淵國小一帶居民有使用「水溶氣」的紀錄，該地水溶氣主要源自於古地層所蘊含之有機質因厭氧消化所產生的甲烷。國內學者過去在蘭陽平原所做的調查，雖然呈現出當地地下水的高砷濃度很有可能與水溶氣的存在有所關連，但卻仍無直接、實質的證據。有鑒於近年來鐵還原狀態下的厭氧甲烷氧化已引起注意，因此本研究在宜蘭縣武淵地區的水井採樣，除監測現地的生地化參數外，也將井壁的沉積物帶回實驗室進行甲烷添加的厭氧培養試驗，監測 Fe(II)、總砷、As(III)、甲烷濃度變化，並搭配相關的功能性基因的定性定量分析，以及菌種鑑定，以驗證蘭陽平原的水溶氣厭氧氧化作用是否確實為當地地下水高濃度砷的主要驅動力。調查的結果顯示當地地下水確實有砷污染的狀況，且以毒性較高的As(III) 為主要型態，並具有相當含量的 Fe(II)，代表現地環境已為厭氧，除表明有高機率發生鐵還原作用外，也說明該環境適宜厭氧甲烷利用菌群的生存。而菌種鑑定的結果也的確呼應可進行厭氧氧化甲烷作用、並還原Fe(III) 的菌群確實存在。培養試驗的結果顯示非生物與生物性作用都可能共同成為當地砷釋出的驅動力，像是 HCO3- 與砷競爭鐵(氫)氧化物表面的吸附點位，使得砷釋放到地下水中，並且隨著培養實驗進行，實驗組(添加甲烷)與控制組(無額外添加甲烷)皆有鐵還原與砷釋出現象，表示甲烷與其他現地有機物皆能成為當地鐵還原菌的電子供給者以發生鐵還原作用並使砷釋出。然而，培養結果卻觀察到 As(III) 的生成並非微生物厭氧氧化甲烷造成的，推測主要為地下水中的 Fe(II) 將 As(V) 還原所致。本篇研究為第一個利用蘭陽平原地下水中的微生物進行培養實驗並證明生物性的鐵還原作用是造成當地砷釋出的主因，並且甲烷能以電子供給者的角色驅動砷釋出。;High arsenic (As) concentration in groundwater is a worldwide public health issue, and millions of peoples’ health are threatened. Groundwater in Lanyang plain of Taiwan is contaminated by high content of As. Residents rely heavily on groundwater, so As-containing groundwater poses potential health hazards to local people. In most case, the liberation of As from sediment are caused by microbial reductive dissolution of iron oxide hydroxide, and organic carbon would be used as electron donor. There is plenty of CH4 emerging from wells in Wuyuan township of Lanyang plain, so the hypothesis of this study is CH4 can serve as electron donor for anaerobic menthanotrophs and triggering As(V) or As(III) mobilizing. Biogeochemical parameters and microbial community of the wells in Wuyuan township were analyzed for gaining background data, and sediments in the wells were collected for the anaerobic CH4 adding incubations. The main findings are three. First, the competitive sorption of As and HCO3- to iron oxide hydroxide can trigger As released by abiotic reaction. Second, CH4 and non-CH4 in situ organic can carbon function as electron donor for iron-reducing bacteria and cause As liberate into groundwater by reductive dissolution of iron oxide hydroxide. Third, As(III) generating is most likely because of As(V) reducing by Fe(II) in abiotic reaction. This is the first study proving that the reason of As contamination in Lanyang plain is caused by biological iron reduction, and CH4 can be the role of electron donor.
Appears in Collections:	[Graduate Institute of Environmental Engineering ] Electronic Thesis & Dissertation

Files in This Item:

File	Description	Size	Format
index.html		0Kb	HTML	13	View/Open

社群 sharing

Loading...