環(huán)境中全氟辛基磺酸前體物好氧生物降解進(jìn)展

周紹宏,王淦淦,張利蘭

環(huán)境中全氟辛基磺酸前體物好氧生物降解進(jìn)展

周紹宏,王淦淦,張利蘭*

(重慶大學(xué)煤礦災(zāi)害動(dòng)力學(xué)與控制國(guó)家重點(diǎn)實(shí)驗(yàn)室,重慶 400044)

目前,在土壤、大氣、水體等各種環(huán)境介質(zhì)中均檢測(cè)到了全氟辛基磺酸(PFOS)及其前體物(PrePFOS)的存在.自然條件下,PrePFOS的非生物降解量可以忽略不計(jì),其生物降解的途徑和降解量是預(yù)測(cè)未來PFOS環(huán)境行為的基礎(chǔ).本文對(duì)PrePFOS在環(huán)境介質(zhì)中的分布以及生物降解進(jìn)行了綜述.在所有的PrePFOS中,關(guān)于N-乙基全氟辛基磺酰胺乙醇(EtFOSE)的研究較深入,其在土壤、活性污泥、沉積物中的降解途徑及PFOS產(chǎn)量均有報(bào)道,EtFOSE的降解速度及其PFOS產(chǎn)量與介質(zhì)的理化性質(zhì)、微生物群落結(jié)構(gòu)密切相關(guān),N-乙基全氟辛基磺酰胺乙酸(EtFOSAA)脫羧轉(zhuǎn)化為N-乙基全氟辛基磺酰胺(EtFOSA)是EtFOSE轉(zhuǎn)化為PFOS的主要限速步驟.最新關(guān)于EtFOSE在土壤中的好氧生物降解的研究首次提出全氟辛基磺酰胺乙酸(FOSAA)脫羧形成全氟辛基磺酰胺(FOSA)是EtFOSE轉(zhuǎn)化成PFOS的另外一個(gè)可能的限速步驟.全氟辛基磷酸酯(DiSAmPAP)在沉積物中的半衰期>380d,其可能的降解途徑是先降解為EtFOSE,之后降解為PFOS.最后,在已有研究基礎(chǔ)上,提出目前PrePFOS研究存在的問題及今后的研究方向.

全氟辛烷磺酸前體物；分布特征；好氧生物降解；土壤；活性污泥；沉積物

PFOS是一種由疏水性全氟烷基鏈和親水的尾部官能團(tuán)構(gòu)成的表面活性劑,廣泛應(yīng)用于地毯、鞋材、紙張、消防泡沫、影印涂料、地板打磨等工業(yè)和民用領(lǐng)域[1].由于氟是電負(fù)性最強(qiáng)的元素(-4.0), PFOS具有很強(qiáng)的穩(wěn)定性,在環(huán)境中持久存在,沿食物鏈累積放大.毒理學(xué)研究證實(shí)PFOS對(duì)人和動(dòng)物具有肝臟、胚胎發(fā)育、生殖和神經(jīng)等多種毒性[1-2].2009年5月,PFOS及其鹽類作為新的持久性有機(jī)污染物被列入《關(guān)于持久性有機(jī)污染物的斯德哥爾摩公約》,除鍍鉻等特殊行業(yè),大部分國(guó)家開始限制此類物質(zhì)生產(chǎn)使用.然而,環(huán)境中PFOS的污染狀況并未因此得到顯著改善,尤其是在中國(guó)、古巴等發(fā)展中國(guó)家[3],環(huán)境中PFOS依然維持較高的濃度水平.環(huán)境中的PFOS除了直接生產(chǎn)來源外,PFOS前體物(PrePFOS)的降解轉(zhuǎn)化是其主要來源[3-5],其降解產(chǎn)生PFOS需引起重視.

目前,國(guó)內(nèi)外制定的相關(guān)法律政策主要用于規(guī)范有機(jī)氟化物的使用,未發(fā)現(xiàn)專門針對(duì)PrePFOS的規(guī)范要求.自美國(guó)頒布毒性物質(zhì)控制法案(Toxic Substances Control Act)規(guī)定183項(xiàng)PFOS及相關(guān)化學(xué)物質(zhì)的使用規(guī)則后,加拿大和歐洲分別修訂/發(fā)布了《加拿大環(huán)境保護(hù)法案,1999》和《關(guān)于限制全氟辛烷磺酸銷售及使用的指令》(2006/122/EC)規(guī)定PFOS或含PFOS的產(chǎn)品的生產(chǎn)、使用、銷售和進(jìn)口.2000年起3M公司逐漸停止生產(chǎn)PFOS.2017年,我國(guó)發(fā)布了《中國(guó)嚴(yán)格限制的有毒化學(xué)品名錄》,將PFOS及其鹽類和全氟辛基磺酰氟列為管控化學(xué)品,全面限制此類物質(zhì)的生產(chǎn)使用.

本文結(jié)合國(guó)內(nèi)外文獻(xiàn),結(jié)合典型PrePFOS理化性質(zhì)及其污染現(xiàn)狀,對(duì)其在不同環(huán)境介質(zhì)中的污染特征以及好氧生物轉(zhuǎn)化為PFOS的機(jī)制進(jìn)行綜述,并提出PrePFOS的研究需求.

1 典型PrePFOS

PrePFOS是指一類在環(huán)境或生物體內(nèi)能轉(zhuǎn)化成PFOS、氮烷基取代的全氟辛基磺酸胺類物質(zhì)(化學(xué)通式為C8F17SO2NRR￠),是以辛基磺酰氟為原料,利用電化學(xué)氟化法合成,如以辛基磺酰氟為原料合成支鏈和直鏈全氟辛基磺酰氟(POSF).POSF水解可直接產(chǎn)生PFOS和及其鹽類物質(zhì),而與甲基胺或乙基胺反應(yīng)可產(chǎn)生烴基磺胺類物質(zhì)如N-甲基全氟辛基磺酰胺(MeFOSA)和EtFOSA.這些磺酰胺類物質(zhì)可與碳酸亞乙酯合成磺酰胺醇類物質(zhì)如N-甲基全氟辛基磺酰胺乙醇(MeFOSE)和EtFOSE,此兩種物質(zhì)被用來合成氟化乙酸類物質(zhì),如EtFOSAA;或合成磷酸酯類物質(zhì),如DiSAmPAP. PrePFOS一般在環(huán)境中呈中性,水溶性低,揮發(fā)性適中.幾種環(huán)境中常見的PrePFOS的理化性質(zhì)和化學(xué)結(jié)構(gòu)見表1.

表1 典型PrePFOS的理化性質(zhì)及結(jié)構(gòu)式

續(xù)表1

從1967年開始,EtFOSE被大量用于表面活性劑和殺滅蟑螂或螞蟻的殺蟲劑.目前,EtFOSE、EtFOSA、SAmPAP、DiSAmPAP等仍在中國(guó)、巴西、阿根廷等國(guó)家生產(chǎn)使用.巴西在2004~2015年期間生產(chǎn)FOSA和PFOS的總量為167~487t[10],中國(guó)在2001~ 2011年期間生產(chǎn)PFOS和PrePFOS的總量約1.8× 103t[11].據(jù)估計(jì),僅在1970~2002年期間,PFOS和PrePFOS全球總生產(chǎn)量高達(dá)9.6×104~1.2×105t.其中,釋放到空氣和水中PFOS和PrePFOS的總量約為4.5×104t,PrePFOS的環(huán)境釋放量要比PFOS高1~2個(gè)數(shù)量級(jí)[7,12].因此,PrePFOS是環(huán)境中PFOS的一個(gè)巨量的潛在來源.

2 PrePFOS在環(huán)境介質(zhì)中的污染現(xiàn)狀

在生產(chǎn)和使用過程中,PrePFOS通過多種途徑進(jìn)入水、土壤、大氣等環(huán)境介質(zhì)中.PrePFOS可隨廢水排入污水處理廠,或隨固體介質(zhì)進(jìn)入垃圾填埋廠.污水處理廠中的非離子型PrePFOS或揮發(fā)至大氣層,或隨出水進(jìn)入自然水體,吸附在活性污泥中的PrePFOS可作為生物固體施肥到土壤中,或進(jìn)入垃圾填埋廠,滲透進(jìn)入土壤或地下水.大氣中的PrePFOS可隨氣流完成長(zhǎng)距離遷移,或經(jīng)沉降作用回到地表,進(jìn)入河流或滲入土壤.河流中的PrePFOS匯流進(jìn)入海洋環(huán)境,或通過飲水或表面接觸進(jìn)入水生動(dòng)物體內(nèi),或被沉積物吸附[13].土壤中的PrePFOS隨表面徑流或雨水沖刷進(jìn)入到河流,或轉(zhuǎn)移至植物體內(nèi),或滲透至地下水.當(dāng)?shù)叵滤挥糜诠喔然蝻嬘脮r(shí),隨之進(jìn)入土壤、植物、動(dòng)物及人體內(nèi).除此以外, PrePFOS還可以通過呼吸和飲食等生命活動(dòng)進(jìn)入人體內(nèi).

2.1 水體和底泥中PrePFOS污染現(xiàn)狀

水體為污染物的主要容納體,PrePFOS在其中廣泛存在.工業(yè)區(qū)附近的水體中PrePFOS的濃度通常很高,美國(guó)一家滅火器工廠附近的地下水體中[14], FOSA濃度高達(dá)6.57mg/L.PrePFOS在自然水體中的濃度較低.Ahrens等[13]發(fā)現(xiàn)大西洋中,FOSA的濃度(302pg/L)大于PFOS 的濃度(291pg /L).Busch等[15]在東格陵蘭島附近海水中亦發(fā)現(xiàn)FOSA的濃度高于PFOS,這主要源于FOSA揮發(fā)、遷移、沉降至該地區(qū).在日本東京灣水體中檢測(cè)到的PrePFOS包括FOSA和N-EtFOSAA,總量為16.7~42.3ng/L[16].太湖水樣中FOSA的平均檢測(cè)濃度為15ng/L[17].

PrePFOS在水體中的廣泛分布性且較大底泥/水分配系數(shù)[18],使其不可避免的遷移到底泥中.日本東京灣表層底泥[16]檢測(cè)到包括EtFOSAA、FOSA等多種PrePFOS,其濃度總量為0.29~0.36ng/g.2012年,DiSAmPAP在海水底泥中首次檢出[19],濃度范圍為32~200pg/g,可被降解為各種PrePFOS,解釋了為何近年來底泥中DiSAmPAP潛在中間產(chǎn)物EtFOSAA的濃度大于或接近于PFOS的濃度(0.246ng/g)[16,20].

2.2 土壤和大氣中PrePFOS的污染現(xiàn)狀

在早期關(guān)于土壤中異源性有機(jī)污染物分析中,多只關(guān)注PFOS,未將PrePFOS列入檢測(cè)清單[21].近些年來,EtFOSAA、FOSAA、FOSA等PrePFOS引起關(guān)注并在土壤中被頻繁檢出[22].由于低水溶性以及較高的有機(jī)質(zhì)吸附性,PrePFOS常吸附在活性污泥上,隨之排放到表層土壤中[20,23-24].有研究發(fā)現(xiàn)施用生物固體肥料超過10年的土壤中PFOS和PrePFOS的總濃度高達(dá)5μg/g[24].

PrePFOS的pKa一般高于環(huán)境pH值而以中性分子形態(tài)存在,水溶性較弱且揮發(fā)性適中(如表1所示),易從其它環(huán)境介質(zhì)中揮發(fā)至大氣,許多工業(yè)或非工業(yè)區(qū)空氣均檢測(cè)到了高濃度的PrePFOS[6,25-26].大氣中PrePFOS的長(zhǎng)距離遷移被認(rèn)為是PFOS全球性分布的主要元兇之一[3,27].在德國(guó)某海濱村莊上方空氣中[32],FOSA和MeFOSE濃度范圍分別為0.5~13和0.1~4.1pg/m3.北極上方空氣中[30],MeFOSE和EtFOSE的濃度范圍分別為2.6~3.1和1.0~8.9pg/m3.

3 環(huán)境介質(zhì)中PrePFOS的好氧生物降解

氯化作用、臭氧化作用或活性炭吸附與活性污泥聯(lián)用法等常規(guī)污水處理技術(shù)都難以有效降解PrePFOS.因此,某些污水處理廠出水口PFOS的濃度大于進(jìn)水口的濃度[29]主要是因?yàn)镻rePFOS的生物降解導(dǎo)致了PFOS濃度的上升.目前,關(guān)于PrePFOS的生物降解的研究非常有限(已有研究如表2所示),很多科學(xué)問題還存在爭(zhēng)議,但是PrePFOS通過生物過程可以降解為PFOS已成為共識(shí).PrePFOS的生物降解主要涉及非氟化官能團(tuán)的降解,非生物作用如水解、直接光解和間接光解對(duì)PrePFOS降解為PFOS影響較小[30],可以忽略不計(jì).

表2 環(huán)境介質(zhì)中PrePFOS好氧生物轉(zhuǎn)化的研究進(jìn)展

3.1 FOSA的生物降解

FOSA是較高分子量PreFOS降解為PFOS主要中間產(chǎn)物之一.Murakami等[39]首次研究了土壤滲濾液中FOSA的生物降解,證實(shí)了少部分FOSA可以被生物降解為PFOS.并進(jìn)一步證實(shí)在水體中FOSA同樣可以被微生物降解為PFOS,添加營(yíng)養(yǎng)物質(zhì)和土壤會(huì)加快PFOS的產(chǎn)生速度.不同水體中負(fù)載同樣濃度FOSA的降解實(shí)驗(yàn)發(fā)現(xiàn),在表面徑流水和地下水中檢測(cè)到了PFOS,而在污水處理廠出水和雨水中未檢測(cè)出,這可能是由于后2種介質(zhì)中含有固體顆粒,對(duì)FOSA有強(qiáng)吸附性,因而阻礙了水體微生物降解FOSA.研究表明FOSA也可以在生物體內(nèi)降解. Chen等[40]發(fā)現(xiàn)在鯉魚體內(nèi),FOSA的支鏈異構(gòu)體比相應(yīng)的線性異構(gòu)體更快地被消除.Zhao等[41]發(fā)現(xiàn)FOSA在大豆和南瓜體內(nèi)可被依次降解為PFOS、全氟己基磺酸(PFHxS)和全氟丁基磺酸(PFBS).

3.2 EtFOSA的生物降解

Avenda?o等[32]采用半封閉的體系研究了182d內(nèi)EtFOSA在土壤中的好氧生物降解,發(fā)現(xiàn)EtFOSA在土壤中的半衰期為(13.9±2.1)d,PFOS的生產(chǎn)量是4.0%(物質(zhì)的量百分比),證實(shí)了EtFOSA通過烷基氧化產(chǎn)生FOSAA途徑的存在;FOSA和FOSAA是EtFOSA2個(gè)主要的降解產(chǎn)物,且這2種PrePFOS在土壤中半衰期很長(zhǎng),這也解釋了很多環(huán)境介質(zhì)中FOSAA和FOSA的濃度高于PFOS的現(xiàn)象[42-43].

3.3 EtFOSE的生物降解

EtFOSE是電氟化反應(yīng)的重要產(chǎn)物,也是合成下游產(chǎn)物如磷酸酯的重要原料,關(guān)于它在環(huán)境介質(zhì)中生物降解的研究較為深入.目前關(guān)于EtFOSE 的好氧生物降解途徑如圖1所示,圖中:單實(shí)線指示 EtFOSE 在半封閉土壤體系中好氧生物降解途徑[40];虛線為 EtFOSE 在日本青鳉魚體內(nèi)降解途徑[48];雙實(shí)線為本課題組首次提出的另外一種降解途徑[41].(1)單實(shí)線路徑:EtFOSE通過氧化轉(zhuǎn)化為EtFOSAA,隨后經(jīng)過脫羧反應(yīng)生成EtFOSA,接著EtFOSA直接脫去烷基轉(zhuǎn)化為FOSA,或先通過烷基氧化為FOSAA,再經(jīng)脫羧作用轉(zhuǎn)化為FOSA,最后經(jīng)脫氨轉(zhuǎn)化為最終產(chǎn)物PFOS.(2)單虛線路徑:部分EtFOSE直接脫醇轉(zhuǎn)化為EtFOSA,一部分則通過氧化先轉(zhuǎn)化為EtFOSAA,之后再脫羧轉(zhuǎn)化為EtFOSA,還有一部分EtFOSE先通過脫烷基反應(yīng)生成FOSE; EtFOSA隨后再脫烷基生成FOSA,部分FOSE直接脫醇轉(zhuǎn)化為FOSA,其余FOSE經(jīng)過氧化轉(zhuǎn)化為FOSAA,再脫羧轉(zhuǎn)化成FOSA;FOSA最后脫氨轉(zhuǎn)化為PFOS.(3)雙實(shí)線路徑:EtFOSE直接脫磺酰胺一步生成PFOS.

圖1 EtFOSE主要的好氧生物降解途徑

Lange[37]發(fā)現(xiàn)在活性污泥中,兩種濃度的EtFOSE均通過圖1單實(shí)線中五步反應(yīng)路徑逐步轉(zhuǎn)化為PFOS.相比之下,低濃度EtFOSE的生物轉(zhuǎn)化速率和轉(zhuǎn)化成PFOS的量分別是高濃度的2倍和 3 倍.Boulanger 等[45]發(fā)現(xiàn),在好氧活性污泥中EtFOSE僅通過虛線反應(yīng)路徑兩步就轉(zhuǎn)化為PFOS的直接前體物FOSA,可能由于反應(yīng)時(shí)間較短(96h),未檢測(cè)到終產(chǎn)物PFOS;在厭氧條件下,EtFOSE不能被生物降解. Rhoads等[35]發(fā)現(xiàn),在好氧活性污泥中,EtFOSE的中間產(chǎn)物EtFOSA既可以經(jīng)過烷基氧化成FOSAA,之后脫羧形成FOSA,也可以直接脫烷基變成FOSA,表明EtFOSE可經(jīng)過單實(shí)線路徑轉(zhuǎn)化為PFOS.在沉積物中,EtFOSE通過單實(shí)線反應(yīng)轉(zhuǎn)化為PFOS,未發(fā)現(xiàn)EtFOSA直接脫烷基轉(zhuǎn)化成FOSA途徑的存在[38].盡管Lange[37]在研究EtFOSE的活性污泥降解時(shí),中間產(chǎn)物中檢測(cè)到了PFOA,他提出可能是PFOSI經(jīng)非生物的單電子轉(zhuǎn)移機(jī)制降解成PFOA,然而,后面所有研究中均未發(fā)現(xiàn)FSOA.推測(cè)FOSA的檢出可能來自母體物的不純或背景值.

圖2 DiSAmPAP在環(huán)境介質(zhì)中可能的降解途徑

Avenda?o等[32]在半封閉體系中考察了EtFOSE在加拿大某未開墾土壤中的好氧生物轉(zhuǎn)化行為并分析計(jì)算了單實(shí)線路徑中各物質(zhì)的半衰期和反應(yīng)速率.本課題組在其研究基礎(chǔ)上,在封閉體系中,進(jìn)一步探究了EtFOSE在不同性質(zhì)土壤中的降解速率和降解途徑,首次利用KinGUII模型分析了EtFOSE及其代謝產(chǎn)物的降解速率[35].結(jié)果發(fā)現(xiàn):在弱堿性土壤(pH=7.8)中,EtFOSE、EtFOSAA、EtFOSA、FOSAA、FOSA的半衰期分別約為30d,300~400d,20~25d, 100d,35~50d;在酸性土壤(pH=5.5)中,EtFOSAA、EtFOSA、FOSAA、FOSA的半衰期分別約為25d, 300d,25d, 245~334d,40d.其中FOSAA和EtFOSAA為半衰期最長(zhǎng)的2種代謝產(chǎn)物,故EtFOSAA和FOSAA的形成是EtFOSE轉(zhuǎn)化為PFOS的主要限速步驟.此外本課題還利用KinGUII模型分析了Avenda?o等的實(shí)驗(yàn)數(shù)據(jù),發(fā)現(xiàn)單實(shí)線途徑不能得到很好的總體擬合度,基于EWAGA數(shù)據(jù)庫(kù),首次提出EtFOSE直接降解為PFOS這一新路徑,數(shù)據(jù)得到了良好的總體擬合度[33].

本課題組封閉體系所用2種土壤的主要差別為pH值的不同(5.5和7.8),而且實(shí)驗(yàn)結(jié)果表明EtFOSE在2種土壤中降解、產(chǎn)物半衰期、反應(yīng)速率以及PFOS產(chǎn)率(1.06%和5.49%)存在顯著差異,EtFOSA、FOSAA、FOSA都具有可電離的基團(tuán)(如羥基、氨基、羧基),在不同的pH值環(huán)境中,各物質(zhì)的好氧生物降解行為會(huì)發(fā)生不同程度的改變.另外,各物質(zhì)的同分異構(gòu)體之間pKa也存在差異,EtFOSE和其降解過程中的產(chǎn)物如EtFOSE中直鏈?zhǔn)秸伎偟?0%~70%,直鏈?zhǔn)紼tFOSE在環(huán)境pH值范圍內(nèi)呈中性,pKa低于支鏈?zhǔn)?直鏈?zhǔn)紼tFOSA和FOSA在酸性土壤(pH=5.4)中分別呈中性和約10%帶負(fù)電荷,在堿性土壤(pH=7.4和7.8)中分為5%~50%和50%~90%帶負(fù)電荷.Liu等[36]研究了105d內(nèi)EtFOSE同分異構(gòu)體在土壤中的好氧生物降解行為,發(fā)現(xiàn)直鏈?zhǔn)紼tFOSE和支鏈?zhǔn)紼tFOSE的半衰期分別為9.6d和8.7d,無統(tǒng)計(jì)差異;中間產(chǎn)物EtFOSAA和FOSA的支鏈?zhǔn)骄憩F(xiàn)出生物降解的優(yōu)勢(shì),EtFOSA相反,直鏈?zhǔn)胶椭ф準(zhǔn)桨胨テ诜謩e為80.8d和11.2d.此外,土壤的微生物群落結(jié)構(gòu)也會(huì)對(duì)其降解機(jī)制產(chǎn)生影響,目前關(guān)于微生物群落結(jié)構(gòu)差異對(duì)PrePFOS降解具體影響機(jī)制研究還未見報(bào)道.

3.4 全氟磷酸二酯(DiSAmPAP)的生物降解

DiSAmPAP是商業(yè)品FC-807的主要成分, 2002年以前被大量用于食品包裝,由于分析技術(shù)等原因,在2012年才在底泥中首次檢出[20],同時(shí)在底泥中檢測(cè)到了不同濃度的EtFOSAA、MeFOSAA、FOSA、FOSAA和PFOS,相關(guān)性分析顯示EtFOSAA和MeFOSAA與DiSAmPAP濃度相關(guān),表明EtFOSAA和MeFOSAA可能是其降解中間產(chǎn)物,之后進(jìn)一步降解為PFOS,可能的降解途徑如圖2所示.進(jìn)一步的底泥微生物降解DiSAmPAP的實(shí)驗(yàn)發(fā)現(xiàn),在4或20℃培養(yǎng)條件下,DiSAmPAP在沉積物中均未被生物降解,在底泥中的半衰期> 350d[38].氟化物的吸附性隨著碳鏈的增加而增大,DiSAmPAP大分子結(jié)構(gòu)(分子量:1203)、低水溶性[20]、以及底泥中較低的微生物活性,共同導(dǎo)致DiSAmPAP極低的生物降解速率.

4 結(jié)語

4.1 PrePFOS是環(huán)境中PFOS的一個(gè)巨大潛在來源,全球范圍內(nèi)均有檢出.工業(yè)區(qū)附近水體中PrePFOS,濃度尤高,FOSA檢出頻率最高. 土壤中PrePFOS主要來自于活性污泥的土地利用或堆放以及雨、雪等沉降作用.

4.2 目前關(guān)于PrePFOS在環(huán)境中的好氧生物降解的研究多側(cè)重于土壤、活性污泥和海底沉積物. 同種PrePFOS在不同環(huán)境介質(zhì)中的降解行為存在較大差異.

4.3 土壤中EtFOSE和EtFOSA均被證實(shí)可降解為PFOS,但降解機(jī)制受土壤理化性質(zhì)顯著影響.

4.4 展望:目前關(guān)于PrePFOS生物降解多集中于研究pH值、有機(jī)質(zhì)等非生物因素對(duì)其生物轉(zhuǎn)化動(dòng)力學(xué)和途徑的影響,很少探討同分異構(gòu)體和微生物群落結(jié)構(gòu)對(duì)PrePFOS生物轉(zhuǎn)化機(jī)制的影響.微生物是PrePFOS生物轉(zhuǎn)化的主導(dǎo)者,但其在PrePFOS降解過程中的具體作用機(jī)制尚未明確.同時(shí),關(guān)于PrePFOS對(duì)其賦存介質(zhì)的理化性質(zhì)以及其中微生物群落結(jié)構(gòu)和功能的影響未曾見報(bào)道,在未來研究中應(yīng)得到關(guān)注.此外,對(duì)于DiSAmPAP在環(huán)境中的好氧生物降解研究還有待進(jìn)一步研究.

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Aerobic biodegradation of perfluorooctane sulfonateprecursors in different environment media.

ZHOU Shao-hong, WANG Gan-gan, ZHANG Li-lan*

(State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China)., 2019,39(9)：3967~3975

As one of persistent organic pollutants, perfluorooctane sulfonate (PFOS) has been widely detected in various environmental media and shows multiple toxic effects on human and animals. One of its main sources is from the biotransformation of PFOS precursor (PrePFOS). PFOS and PrePFOS have been found in various environmental media like soil, air and water. Understanding the biodegradation pathway and PFOS yield of PrePFOS are useful to predict the environmental fata of PFOS due to that its PFOS yield from abiotic degradation could be ignored. In this study, the occurrence and biodegradation of PrePFOS in different environmental media were summarized. Of all the PrePFOS, N-ethyl perfluorooctane sulfonamidoethanol (EtFOSE) were mostly explored. Its biodegradation pathway and PFOS yield have been studied in soil, activated sludge, and sediment, which have found that its biodegradation mechanism is closely related with the physicochemical properties and microbial community structure of the medium. The decarboxylation of N-ethyl perfluorooctane sulfonamidoacetic acid (EtFOSAA) to N-ethyl perfluorooctane sulfonamide (EtFOSA) is the main rate-limiting step for the conversion of EtFOSE to PFOS. The latest research on aerobic biodegradation of EtFOSE in soil first proposed that decarboxylation of perfluorooctane sulfonamidoacetic acid (FOSAA) to perfluorooctane sulfonamide (FOSA) might be another rate-limiting step in the conversion of EtFOSE to PFOS. EtFOSE-Based Phosphate Diester (DiSAmPAP) had been widely used in various commercial products before 2003, and it had not been detected in sediment until 2012 due to its high Kow value and the lack of detection technology. Its half-life was predicted to be > 380d and it might be biodegradated into EtFOSE firstly and finally transformed into PFOS. And the existing problems and future research direction were discussed too.

perfluorooctane sulfonate precursor(PrePFOS)；distribution characteristics；aerobic biodegradation；soil；activated sludge；sediment

X172

A

1000-6923(2019)09-3967-09

周紹宏(1995-),男,重慶秀山人,重慶大學(xué)碩士研究生,主要從事土壤有機(jī)污染物危害及降解研究.

2019-02-18

國(guó)家自然科學(xué)基金資助項(xiàng)目(41603109);重慶市基礎(chǔ)科研與前沿技術(shù)研究專項(xiàng)(cstc2017jcyjAX0362);中央高?；究蒲袠I(yè)務(wù)費(fèi)資助項(xiàng)目(106112016CDJXY240001,106112017CDJQ218844);重慶市留學(xué)回國(guó)人員創(chuàng)新資助項(xiàng)目重點(diǎn)項(xiàng)目

*責(zé)任作者, 副教授, lilanzhang@cqu.edu.cn