Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/27769
標題: 雙苯環有機化合物之分析技術建立 及其生物降解之研究
Analysis Method and Biodegradation of Biphenyl Organic Compounds
作者: 周希瓴
Chou, Shin-Ling
關鍵字: biodegradation;生物降解;PBDE;SPME;SPME;PBDE
出版社: 土壤環境科學系所
摘要: 
Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous in our environment and come mainly from the incomplete combustion and pyrolysis of fossil fuels, organic materials, and wood. Napthalene (NAP)is the simplest fused polycyclic aromatic hydrocarbon. On the other hand, due to the wide distribution of polybrominated diphenyl ethers (PBDEs) flame retardants in the diverse environmental media in the world, the environmental fate of bromodiphenyl ethers is of interest. Currently, little is known about the transformation of these compounds, and in particular, about the microbial potential to degrade them.
A HS (headapace)-solid phase microextraction (SPME) has grown wide popularity in recently years for the analysis organic compounds in environmental samples. In this study, two kinds of commercially available fibers, 100 μm polydimethylsiloxane (PDMS) and 85 μm polyacrylate (PA), were evaluated through the extraction efficiency of NAP and PBDEs. The extraction time, extraction temperature and salt concentration of organic compounds were investigated for optimizing the SPME method. Increasing the temperature to 60 ℃ can increase the sensitivity of organic compounds and short the equilibrium time. The most suitable salt concentration was 30 %. The obtained regression coefficients are higher the 0.98. Detection limits of this method can be lower down to 0.01 mg/L.
In this study, the degradation of three kinds of biphenyl organic compounds (naphthalene, diphenyl ether and monobrominatediphenyl ether) by Pseudomonas putida was investigated. With P. putida, the naphthalene was degraded by 70 % of the original level in 14 days. In presence of P. putida within 10 days, the biodegradation rates of naphthalene only, naphthalene with sodium salicylate and naphthalene with FeCl3 were 0.13, 0.25, and 0.16 day-1, respectively. However, during 10 days, biodegradation efficiency of naphthalene with FeCl3 was more than that with sodium salicylate. One the other hands, the degradation of diphenyl ether is obvious but not for monobrominatediphenyl ether with P. putida.
For the biodegradation of 4-monobrominated diphenyl ether (4-BDE also call BDE-3), the degradation of 4-BDE was investigated with aerobic and anaerobic sludges. Under aerobic conditions, toluene and diphenyl ether were used as auxiliary carbon sources to stimulate the biodegradation of 4-BDE. The biodegradation of 4-BDE with toluene around 57 % is higher than that around 37 % with diphenyl ether and around 44 % with 4-BDE only at 15 days. No diphenyl ether was observed, indicating probably 4-BDE oxidized in the aerobic sludge. In anaerobic biodegradation, the removal of 4-BDE is about 30 %~80 % within 12 days by village's and community's anaerobic bacterial communities in their sludges. The main biodegradation byproducts of 4-BDE were determined to be diphenyl ether and bromide ions, indicating debromination process in these anaerobic sludges.
We investigated microbial degradation of mono-BDE by enriched anaerobic microbial consortia from Li-Ming and Chung-Hsing community anaerobic sludges. We used DGGE (denaturing gradient gel electrophoresis)to sieve 11 bands and 10 bands that were amplified from these bacterial 16S rRNA genes DNA by PCR(polymerase chain reaction) for the degradation experiments of PBDE from Chung-Hsing and Li-Ming anaerobic sludges, respectively. These microorganisms which may be able to degrade mono-BDE have different DGGE patterns. In both sludges, we found the Clostridium sp. which has the similarity about 70 % to 90 %. In these two anaerobic sludges, several microorgamisms disappeared after adding mono-BDE. Around 10 to 11 microorganism species have the tolerance or degradation ability for mono-BDE.
In addition, these anaerobic sludges can not degrade DBDE(deca-brominated diphenyl ether, BDE-209) in one half year incubation. To increase the removal efficiency, two additional dosages of 0.025 g/mL and 0.05 g/mL ZVI (microscale zero-valent iron) were added into these biodegradation systems. In existence of 0.05 g/mL ZVI, ZVI dominates the degradation process. Comparing to DBDE only and 0.025 g/mL ZVI only systems, the microorganisms can enhance the degradation efficiency of PBDEs in 0.025 g/mL ZVI system. It shows that the combined ZVI and anaerobic microorganisms can increase DBDE degradation ability. In the anaerobic microorganism-ZVI system, DGGE profiles of Li-Ming and Chung-Hsing sludges showed 5 and 6 bands corresponding to different species. The microbial diversity in biodegradation system for DBDE is smaller than mono-BDE. These better understandings of biological degradation of brominated diphenyl ether can facilitate the biodegradation and the fate of these chemicals in the environment.

多環芳香烴化合物(polycyclic aromatic hydrocarbons,簡稱PAHs)主要是由兩個或兩個以上的苯環所組成,主要是經由不完全燃燒或是由石化燃料不完全燃燒所產生,在大自然環境中廣泛的流佈,其中napthalene是最簡單的芳香烴化合物。另一方面,多溴聯苯醚(polybrominated diphenyl ethers, 簡稱PBDEs)為目前環境新興有機污染物之一且在環境中常被監測到,但目前關於這些化合物在環境中的轉化並不是很了解,因此PBDEs的宿命備受到重視,尤其是在生物降解方面。
固相微萃取(soild-phase microextraction,簡稱SPME)為近年來發展迅速的一種免溶劑萃取技術,目前也廣泛應用在揮發性、半揮發性極不揮發性物質之分析,SPME的特點為在於萃取時不需使用任何溶劑,而且成本低、操作簡單、快速,具有高萃取效率、高度選擇性和兼具有純化、濃縮樣品。
本研究嘗試以固相微萃取分析方法檢測水體中的naphthalene與PBDEs。藉由polyacrylate(PA)與polydimethylsiloxane(PDMS)兩種不同的SPME纖維材質,以頂空方式間接萃取水體中的naphthalene與PBDEs後,以GC分析有機化合物濃度並計算萃取效率,並且進一步實驗有機化合物的萃取時間、萃取溫度、鹽類濃度等最佳化條件。溫度增加到60 ℃可以增加有機化合物的揮發程度,並可以減少與氣固相的平衡時間,而最適合的鹽分濃度為30 %。這些結果的線性範圍在0.9771到0.9976之間,偵測極限則為0.01 mg/L。整體而言,以85 μm PA萃取PBDE會比100 μm PDMS有較高的萃取效率,然而naphthalene則呈現相反的結果。根據上面結果可以得知,85 μm PA與100 μm PDMS可以適用於水體樣品的環境中以萃取環境有機污染物。
利用Pseudomonas putida 生物降解naphthalene, diphenyl ether 和一溴聯苯醚三種有機化合物,Pseudomonas putida 生物降解naphthalene在14天內共降解了70 %,在實驗期間也另外添加水楊酸鈉及FeCl3促進微生物分解naphthalene,10天內naphthalene降解速率常數為0.13 day-1,額外添加輔助因子水楊酸鈉及FeCl3的降解速率常數分別0.25 和0.16 day-1。從結果可得知水楊酸鈉及FeCl3皆是一個好的輔助因子。
在生物降解研究方面,利用酒廠好氧活性污泥與南投中興新村和台中黎明社區厭氧活性污泥進行一溴聯苯醚(4-monobrominated diphenyl)的生物降解。在好氧生物降解情況下,利用甲苯和diphenyl ether作為輔助碳源促進一溴聯苯醚的生物降解,結果證實,在甲苯與diphenyl ether兩種輔助碳源存在情況下,15天內共降解60 %與40 %,在實驗過程中沒有觀察到diphenyl ether,可能表示一溴聯苯醚在好氧情況下是被氧化的。在厭氧生物降解方面,利用厭氧活性污泥中的微生物降解一溴聯苯醚,在12天內大約降解30 %~80 %,生物降解一溴聯苯醚主要的副產物偵測到diphenyl ether,並且也偵測到溴離子的產生,表示脫溴過程是在厭氧情況下發生的。本研究進一步以分子生物方法探討降解前後之活性污泥菌群結構,以兩種厭氧活性污泥經變性梯度凝膠電泳篩選後,可辨識出許多不同相對位置的條帶以進行16S rDNA序列鑑定,在中興厭氧污泥降解一溴聯苯醚的部分篩選出11個不同的條帶;在黎明厭氧污泥降解一溴聯苯醚的部分篩選出10個不同的條帶,在兩個厭氧系統中均有篩選到與Clostridium sp. 相似度達70 %以上之菌株。研究結果顯示,厭氧污泥降解一溴聯苯醚過後,微生物菌相集中於某些菌群,這些菌群可能具有降解一溴聯苯醚之能力,表示不同厭氧活性污泥下馴養的降解菌群整體上有不同的菌群結構,其中包含相同的優勢菌群。
另外,也利用厭氧活性污泥降解十溴聯苯醚(Deca-BDE, BDE-209),經過半年的時間並沒有發現DBDE有明顯的變化,由此實驗結果顯示此兩種厭氧活性污泥沒有降解DBDE之能力,此外,本實驗額外添加0.025 g/mL與0.05 g/mL兩種劑量的微米級零價鐵(microscale zero-valent iron, MZVI)進行降解DBDE試驗,結果發現,微生物在0.025 g/mL MZVI系統下可以更有效的降解PBDEs,表示MZVI在降解DBDE過程中微生物同時可分解DBDE。在添加ZVI的系統中,在中興厭氧污泥降解十溴聯苯醚的部分篩選出6個不同的條帶;在黎明厭氧污泥降解十溴聯苯醚的部分篩選出5個不同的條帶,優勢菌群種類的數量少於降解一溴聯苯醚的數量,也許微生物菌群無法適應ZVI的存在或更多溴數之化合物對微生物也是一大毒害,相較之下可發現微生物會因為環境不同菌相也會有所不同,這些含溴聯苯醚的生物降解結果可以有助於了解這些化合物在環境中的宿命。
URI: http://hdl.handle.net/11455/27769
Appears in Collections:土壤環境科學系

Show full item record
 

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.