供水管網(wǎng)中微/納米塑料的賦存及污染特性

鄭瑩瑩,張可佳,岑 程,毛如寅,張土喬

供水管網(wǎng)中微/納米塑料的賦存及污染特性

鄭瑩瑩,張可佳*,岑 程,毛如寅,張土喬

(浙江大學(xué)建筑工程學(xué)院,浙江 杭州 310058)

微/納米塑料具有分布廣泛、粒徑小、難降解、可吸附有毒物質(zhì)等特性,其去除效果及對環(huán)境污染的現(xiàn)狀尚不明晰,是當前研究熱點和難點.本文從供水管網(wǎng)中微/納米塑料的來源、分布規(guī)律及水質(zhì)安全危害等角度,概述了全球范圍內(nèi)供水管網(wǎng)中微/納米塑料的研究現(xiàn)狀.結(jié)果表明,給水處理廠出廠水攜帶殘留的微/納米塑料顆粒進入供水管網(wǎng),而塑料材質(zhì)管道在水力、水質(zhì)作用下(流速、機械磨損、消毒劑等)同樣存在微/納米塑料釋放可能.微/納米塑料自身的密度、電荷等固有特性影響了它在供水管網(wǎng)中的空間分布規(guī)律,且在飲用水輸配過程中,微/納米塑料可同有機物、微生物等物質(zhì)反應(yīng),從而影響供水管網(wǎng)的水質(zhì)安全.本文旨在提出未來的研究重點和方向,從而為進一步了解微/納米塑料對飲用水安全的影響及如何控制其污染提供理論基礎(chǔ).

微/納米塑料；供水管網(wǎng)；分布規(guī)律；水質(zhì)安全

塑料污染已成為一個世界性問題,一旦釋放到環(huán)境中,其在環(huán)境中物理化學(xué)和生物因素的作用下會逐步分解成微塑料(尺寸<5mm,MPs)、甚至納米塑料(尺寸<1μm,NPs)[1].研究表明,近10%的塑料最終將以微/納米塑料顆粒(MPs/NPs)的形式進入水環(huán)境[2].因粒徑小、難降解、可吸附有毒物質(zhì)等特性,大量的MPs將對生物體產(chǎn)生毒性作用,造成嚴重的生態(tài)風(fēng)險.而NPs由于粒徑更小,比表面更大,細胞親和力更高,更易于穿透細胞[3],使生物原有機能遭到損傷,如誘導(dǎo)氧化應(yīng)激導(dǎo)致炎癥[4]、DNA損傷、細胞凋亡、脂質(zhì)/能量代謝的改變等[5-6],因此MPs/NPs的危害都不容忽視.在對人體糞便進行MPs/NPs檢測時,結(jié)果表明95.8%的樣本呈陽性[7],且在母嬰的胎盤中同樣發(fā)現(xiàn)了MPs/NPs[8],這說明MPs/NPs不僅可經(jīng)消化道排泄還可通過血液或者臍帶等方式在體內(nèi)傳播甚至停留,從而威脅人類健康[9].人體攝入MPs/NPs的途徑有皮膚接觸[10]、大氣呼吸[11]、食物鏈富集[12]等.其中由于MPs/NPs廣泛分布在水生環(huán)境中,飲用水的使用在日常生活中更是不可避免,因此有必要加深對供水管網(wǎng)中MPs/NPs危害風(fēng)險的認識.

當前凈水處理工藝對MPs/NPs的去除效果有限以及輸配過程中外源侵入[13-14],導(dǎo)致在飲用水中檢測到MPs/NPs的存在.對全球14個國家的159個飲用水樣本檢測發(fā)現(xiàn)81%的樣本中含有MPs/NPs.其中,美國有94%的龍頭水樣品中檢出了MPs/NPs,英國、德國和法國等歐洲國家的飲用水中MPs/NPs檢出率達72%[15].在對中國長沙供水流程中MPs/ NPs的豐度研究發(fā)現(xiàn)水源、出廠水和龍頭水中的豐度分別為2173～3998(平均=2753)、338～400(平均= 351.9)和267～404(平均=343.5)顆粒/L[16],且大多數(shù)聚合物由聚乙烯(PE)、聚丙烯(PP)和聚對苯二甲酸乙二醇酯(PET)組成[17].在塑料供水管道大量使用的今天,我國塑料管道占比已超過55%[18],英國已達到63%,聚氯乙烯(PVC)在美國供水市場中占66%[19].因此,輸配水管道對龍頭水存在MPs/NPs也可能起到重要作用.一旦在供水管網(wǎng)中出現(xiàn)MPs/NPs釋放,且與管道內(nèi)物質(zhì)發(fā)生反應(yīng)產(chǎn)生有害物質(zhì),將會嚴重危害龍頭水水質(zhì)安全.但迄今為止,僅已確定MPs/NPs會存在于水源地、遷移于凈水工藝、殘留于飲用水中,但大部分都只停留在檢測和表征層面,對其在供水管網(wǎng)中的分布規(guī)律及與水中其他物質(zhì)的復(fù)合作用機理研究較少,由此造成的飲用水污染及對人體健康影響尚不明晰.基于此,本文重點分析了供水管網(wǎng)中MPs/NPs的來源,討論了MPs/NPs在供水管網(wǎng)中的分布規(guī)律及賦存特征,總結(jié)了MPs/NPs自身及同管網(wǎng)中其他物質(zhì)復(fù)合作用對管網(wǎng)水質(zhì)安全的影響及危害,并基于MPs/NPs的管網(wǎng)水質(zhì)安全問題,提出未來的研究工作方向及有效控制的措施.

1 供水管網(wǎng)中MPs/NPs的來源

1.1 前驅(qū)來源

供水管網(wǎng)中MPs/NPs的前驅(qū)來源主要來自兩方面,一方面是由于自來水廠原水受到MPs/NPs污染,但其自身去除效果有限;另一方面是部分處理工藝導(dǎo)致塑料碎片化,增加MPs/NPs豐度.水體中的MPs/NPs主要來自陸地運輸,漁業(yè)活動和船舶排放物等,它們通過地表徑流、土壤滲透和大氣運輸?shù)冗M入水環(huán)境.隨著水系統(tǒng)的自然循環(huán),MPs/NPs同樣污染著淡水環(huán)境甚至飲用水水源,其中可作為飲用水水源取水點的太湖[20]西北部表層水中的MPs/NPs含量最高可達25800顆粒/m3,浮游生物樣品中的MPs含量比美國大湖地區(qū)高2個數(shù)量級.而丹江口水庫盡管主區(qū)的污染水平較低[21],但丹江口大壩和人口稠密地區(qū)的采樣點仍然存在污染,調(diào)查結(jié)果分別為(6087±6981)和(15017±454)顆粒/m3,這導(dǎo)致丹江口凈水廠的原水中含有一定量的MPs/NPs.

自來水廠對MPs/NPs的去除作用受自身粒徑的影響[22],大于20μm的MPs/NPs去除率可為99%左右,而小于20μm的MPs/NPs去除率則受處理工藝和原水等不同的影響.Mintenig等[23]對德國西北部以地下水為水源的自來水廠的廢水MPs/NPs檢測結(jié)果就表明,粒徑大于20μm的豐度僅為0～7顆粒/m3.Pivokonsky等[24]也證實了這一結(jié)果,WTP1、WTP2和WTP3(捷克共和國境內(nèi))自來水廠的粒徑為0.2～100μm的MPs/NPs去除率分別為70%,81%和83%,其中殘留MPs/NPs中粒徑范圍占比分別如下,大于50μm幾乎為0%、5～10μm為30%～50%、1～5μm為25%～60%.Wang等[14]對以長江下游為水源的自來水廠進行研究發(fā)現(xiàn)混凝可以很好地去除MPs/NPs,混凝裝置的總體去除效率約為40.5%～54.5%.其中MPs(>10μm)幾乎被全部去除,而MPs(5～10μm)的去除率僅為44.9%～75.0%.這主要是由于較大尺寸MPs/NPs良好的沉降特性以及纖維狀MPs/NPs更易附著于絮狀物上的結(jié)構(gòu)特性.即使Ma等[25]表明添加陰離子聚丙烯酰胺(PAM)可以大大增加鋁鹽去除PE顆粒的百分比,但最終去除率也僅在60%左右.而其他的水處理工藝如砂濾去除MPs的效率僅為29.0%～44.4%.其中纖維、球體和碎片的去除率分別為30.9%～49.3%、23.5%～50.9%和18.9%～27.5%.在臭氧化和活性炭(GAC)過濾過程中,纖維、球體和碎片的去除率分別為38%～52.1%、76.8%～86.3%和60.3%～69.1%[14].由此可見,臭氧化和GAC過濾的去除效果明顯高于常規(guī)處理,但仍然存在一定量的殘留物.

而在水處理過程中有數(shù)據(jù)證明MPs可能會破碎成NPs,從而增加了水中MPs/NPs的豐度[26].Wang等[14]發(fā)現(xiàn)臭氧化使1～5μmMPs的量增加了2.8%～16.0%,這可能是由于剪切流將MPs分解成更小的顆粒和纖維,這與在廢水處理廠中觀察到的情況一致[27].Wu等[22]研究表明生物處理和臭氧化出水中5～20μm顆粒狀MPs/NPs的豐度增加.生物處理中小于20μm的MPs/NPs的豐度平均增加了149.58%,臭氧化中10～20μm的MPs/NPs從1204.7顆粒/L增加到1700.0顆粒/L;5～10μm的MPs/NPs從3233.8顆粒/L增加到3352.8顆粒/L.這可以解釋為MPs/ NPs首先被氧化削弱,然后由于水流的剪切力和空氣曝氣等外力而分解,從而產(chǎn)生較小的MPs/NPs.因此總結(jié)上文,常規(guī)的自來水廠并未針對去除MPs/ NPs設(shè)計優(yōu)化專門的處理工藝,如PP、聚苯乙烯(PS)等MPs/NPs就難以被截留處理而隨出廠水進入到供水管網(wǎng)中[28].其中小于20μm的MPs/NPs占主導(dǎo)地位可達到99.94%,且小于5μm的甚至占到80%以上[14].

表1 各飲用水處理廠對MPs/NPs的去除效果匯總表

1.2 管網(wǎng)中潛在來源

龍頭水中的MPs/NPs與供水管網(wǎng)中管材有關(guān),且供水管網(wǎng)存在釋放MPs/NPs的可能.Gomiero等[32]對挪威中型城市地區(qū)飲用水供應(yīng)管網(wǎng)不同收集點進行MPs/NPs測定時發(fā)現(xiàn),PE在水平分布線上顯示出顯著的增加,可能是由于PE管道被機械磨損造成的.同樣Weber等[33]也報道了供水管道磨損是德國北部一個由地下水供應(yīng)的飲用水供應(yīng)系統(tǒng)中MPs/ NPs分布的主要驅(qū)動因素.最近我國長沙[16]、泰國[34-35]、瑞典[36]等地龍頭水中MPs/NPs的調(diào)研也均證實了這一推論.

同時,管道環(huán)境下不同因素會影響MPs/NPs的釋放.在不同管道液體流動條件下獲得的剪切應(yīng)力、溫度等作用力有助于MPs產(chǎn)生NPs[26].Ekvall等[37]模擬了自然機械力下的微塑料分解過程,僅通過5min就產(chǎn)生了NPs.同樣高溫下聚合物與水接觸水解切斷化學(xué)官能團使其分子量降低,導(dǎo)致聚合物變得更易碎.夏季高溫暴曬條件下的塑料管道則存在著一定的管道老化、碎化風(fēng)險.而持續(xù)的老化則會使表面越來越粗糙,形成裂紋和缺陷,最終導(dǎo)致大塊塑料碎裂成更小的顆粒[38].如Hernandez等[39]發(fā)現(xiàn)在泡制溫度(95℃)下浸泡一個塑料袋泡茶會釋放約116億MPs和31億NPs.Chamas等[40]估計高密度聚乙烯(HDPE)在紫外線照射條件下其比表面降解率可達到9.5μm/yr.

此外,供水管道管壁附著的生物膜以及殘留的消毒劑在一定程度上也會對塑料進行生物分解,從而產(chǎn)生更小的塑料碎片.Shi等[41]則發(fā)現(xiàn)雨水管道中,塑料可在生物作用下連續(xù)分解成較小的塑料碎片.同時飲用水消毒中最常見的消毒劑氯對塑料管道也有一定的影響.Mitroka等[42]將HDPE管道浸沒在氯濃度分別為50,250和500mg/L氯化水溶液中160d的研究發(fā)現(xiàn)次氯酸(HOCl)會加速管道的老化,此外,在消毒劑的作用下,還可能導(dǎo)致MPs/NPs的碎片化.此外,水解是通過聚合物在其表面的斷鏈作用降解聚合物的過程.一項研究報告表明[43],當羧基在酸性條件下自催化水解時,含有雜原子(PU和PET)的聚合物會被水解降解.當微塑料顆粒長時間暴露在低pH值條件和光氧化作用下時, MPs的水解可能會加速提高NPs的豐度.

因此在供水管網(wǎng)中,泵開啟產(chǎn)生的機械磨損、水流下的剪切力、溫度、微生物以及消毒劑等因素都會在一定程度上影響塑料管道中MPs/NPs的釋放,從而增加龍頭水中MPs/NPs的豐度.

表2 管網(wǎng)釋放MPs/NPs的影響因素及作用機理

2 供水管網(wǎng)中MPs/NPs的分布規(guī)律

在長時間長距離的配送過程中,密度較小的MPs/NPs會相互聚集成粒徑較大的團聚體,隨后在重力等作用下沉積至管壁.同時管壁上的生物膜可能對沉積在管壁附近的MPs/NPs有包裹作用. MPs/NPs聚集體的形成在很大程度上受不同的pH值、有機物以及其他因素的影響.密度相對較小、懸浮在水中的MPs/NPs在水基質(zhì)中存在有機物或抗衡離子的情況下會形成團聚體.MPs/NPs間及與其他物質(zhì)的附著力主要受其表面電荷的影響.由于靜電引力,帶正電的MPs/NPs與細胞緊密結(jié)合,而其他帶負電的MPs/NPs通過范德華力、酸堿相互作用以及靜電力與細胞松散地結(jié)合[48].而較大密度的MPs/NPs會在水流的作用下沉積至管底管壁,其中老化的聚苯乙烯微塑料(PS-MPs)比原始PS-MPs更分散,沉降更慢[49].Vahidi等[50]在檢測管道沉積物中微塑料顆粒特性時,發(fā)現(xiàn)相對密度較大的PVC占比較高.且彎曲的管段處相較于直管段能收集到更多的MPs/NPs沉積物,Wu等[15]的研究證實了這一論斷.此外,MPs/NPs對生物膜的附著力主要受其表面電荷的影響,生物膜中重要成分細胞外聚合物(EPS)始終帶負電,其可以通過靜電相互作用與帶正電的污染物聚合體結(jié)合[52].

部分沉積、附著甚至被包裹的MPs/NPs在水流剪切力的作用下,會隨著水流的沖刷,重新釋放到管網(wǎng)水中.Madejski等[53]對沿水運輸路線收集的一些樣品測量了MPs/NPs,結(jié)果顯示MPs/NPs主要集中在入口、入口閥等管道內(nèi)流速短時間內(nèi)變化的地方,因此這一作用在流速突變的情況下尤其明顯.管網(wǎng)水中殘留的消毒劑氯等物質(zhì)同樣對MPs/NPs表面包裹的生物膜具有消解作用,Zhong等[54]研究表明隨著投氯量升高, PE和不銹鋼管內(nèi)生物量均逐漸降低.在此作用下生物膜-MPs/NPs聚積物隨其密度減少又重新懸浮到水中,直接進入龍頭水中.總之,供水管網(wǎng)中的MPs/NPs經(jīng)過一系列的反應(yīng)作用,一部分同管網(wǎng)中的有機物、微生物等物質(zhì)作用從而影響管網(wǎng)水質(zhì)的安全,一部分則隨著水流直接進入龍頭水被用戶所使用.

3 微/納米塑料對水質(zhì)安全的危害

3.1 微/納米塑料直接影響水質(zhì)安全

MPs/NPs是一種新的微生物生態(tài)位,又可作為一些潛在病原體的載體,從而影響管網(wǎng)中微生物的數(shù)量.Zhang等[55]對中國廣東11個地點的沿海沉積物中細菌群落和MPs/NPs豐度進行檢測分析,發(fā)現(xiàn)MPs/NPs豐度與假單胞菌、芽孢桿菌等呈正相關(guān),且<0.5mm的尺寸與芽孢桿菌的正相關(guān)性比其他尺寸的更大.MPs/NPs具有巨大的比表面積,這增加了它們與微生物細胞的潛在接觸面積.在有氧或厭氧條件下,自由基和分子雙氧的催化反應(yīng)可以在它們的表面發(fā)生產(chǎn)生活性氧自由基(ROS)從而誘導(dǎo)細胞毒性[56].Liu等[57]研究結(jié)果表明,NPs能夠誘導(dǎo)Coelicolor M 145菌株細胞產(chǎn)生過量的ROS.低聚苯乙烯濃度會增加ROS的產(chǎn)生,而高ROS水平會誘導(dǎo)抗氧化相關(guān)基因的表達,抗氧化相關(guān)基因表達與抗氧化酶活性相關(guān)[58].

MPs/NPs還可改變細胞的生物學(xué)特質(zhì),易導(dǎo)致微生物產(chǎn)生應(yīng)激反應(yīng).其中NPs可以和蛋白質(zhì)結(jié)合成“蛋白質(zhì)電暈”的形式使其更易穿透細胞膜并與細胞結(jié)構(gòu)相互作用[59].隨后通過吞噬作用、胞飲作用、巨胞飲作用或被動轉(zhuǎn)運和吸收進入細胞膜和各種生物結(jié)構(gòu),改變均質(zhì)膜的性質(zhì)(如機械軟化等)或誘導(dǎo)溶酶體破壞進而誘導(dǎo)細胞死亡[60-61].NPs進入生物體后還可通過阻斷或促進氧化應(yīng)激和免疫系統(tǒng)有關(guān)的基因表達來誘導(dǎo)毒性.Cui等[62]研究結(jié)果表明,高濃度的PS-NPs由于破壞了淡水水蚤的抗氧化系統(tǒng),從而降低了淡水水蚤的抗氧化酶基因表達能力. Zhang等[63]研究發(fā)現(xiàn)水蚤暴露于NPs(75nm)21d將會抑制谷胱甘肽轉(zhuǎn)移酶(GST)的表達,導(dǎo)致氧化應(yīng)激從而降低聚合物對生物體本身的毒性.

一項針對不同管材上(球墨鐵管、聚乙烯管、不銹鋼)微生物的研究表明,盡管PE管壁生物膜上的微生物群落數(shù)較低,但單位群落數(shù)的產(chǎn)嗅能力是最強的[64-65].而國內(nèi)外在靠近用戶端的“最后一公里”普遍采用PE、PVC管作為供水管道,由此造成的異嗅異味問題占到總飲用水嗅味事件的73%[66-67],且通過微生物甲基化作用產(chǎn)生致嗅物是龍頭水異嗅異味問題的重要途徑之一[68].供水管網(wǎng)中的MPs/ NPs或許能夠在一定程度上干擾管網(wǎng)生物膜中的微生物細胞,影響抗氧化酶活性,誘導(dǎo)抗氧化相關(guān)基因的表達,激發(fā)微生物產(chǎn)生更多的ROS[69],從而促進氧化應(yīng)激.在此研究基礎(chǔ)上,本文得到以下推論: MPs/NPs豐度與假單胞菌等產(chǎn)嗅優(yōu)勢菌呈正相關(guān),產(chǎn)嗅優(yōu)勢菌在上述作用下氧化應(yīng)激將產(chǎn)生更多的嗅味物質(zhì)影響龍頭水的口味,從而影響供水的水質(zhì)安全.

3.2 MPs/NPs與其他污染物的復(fù)合危害

MPs/NPs具有粒徑小、難降解、可吸附有毒物質(zhì)等特性,而NPs由于高細胞親和力和高表面積,更易于與其他污染物一起進入生物體,然后在細胞和分子水平上共同誘導(dǎo)生物毒性.影響其毒性的主要因素有濃度、粒徑、暴露時間和所攜帶污染物等[70].此外,生物膜可以改變MPs/NPs的表面性質(zhì),使表面減少疏水性,從而影響MPs/NPs本身的吸附毒性[71].研究表明MPs/NPs可吸附Cu、Cd、Zn、Ni和其他重金屬[72].Sun等[73]發(fā)現(xiàn)PS-MPs在共暴露的最初24h內(nèi)減輕Ag+對大腸桿菌的細胞毒性.一方面,部分Ag+吸附在粒徑為0.1和1.0μm的PS-MPs表面降低了Ag+的生物利用度,從而較少的游離Ag+可以與細胞膜相互作用并破壞細胞膜.另一方面, PS-MPs可以直接粘附在細胞表面,保護大腸桿菌細胞膜不與Ag+相互作用.同時有研究表明吸附的抗生素會改變共存的微生物的群落結(jié)構(gòu).如MPs/NPs吸附抗生素后,改變了跳蟲腸道微生物組的組成和結(jié)構(gòu),并降低了腸道細菌的多樣性[74].同時有研究表明潛在病原體Legionella菌的存在與塑料材質(zhì)密切相關(guān),其在塑料管壁生物膜上以及管網(wǎng)水中的數(shù)量同鑄鐵管相比要高出好幾倍.其中在HDPE中增加了5倍,而在未增塑聚氯乙烯(PVC-U)的情況下則增加了約30倍[75].

圖1 供水管網(wǎng)內(nèi)MPs/NPs的分布規(guī)律及對水質(zhì)安全的危害

吸附作用在老化的MPs/NPs表面更為明顯.研究表明老化的MPs/NPs因其表面結(jié)構(gòu)的變化,對有害物質(zhì)的吸附親和力更高[76].Kelkar等[77]在實驗室條件下將原始塑料暴露于飲用水消毒劑量下(CT值50～150mg min/L),HDPE和PS不能完全抵抗氯化引起的氧化侵蝕,且HDPE新形成了碳-氯(C-Cl)鍵.碳-氯鍵的形成增加了毒性,從而導(dǎo)致聚合物更加疏水,更利于有害物質(zhì)的吸附和積累.Wang等[78]查閱總結(jié)了MPs/NPs對抗生素類、農(nóng)藥類(滴滴涕)、內(nèi)分泌干擾物(雙酚A)、多氯聯(lián)苯、多環(huán)芳烴等有機污染物的吸附作用.主要機制包括疏水相互作用、表面吸附和氫鍵等.而多氯聯(lián)苯類藥物具有致癌性、致突變性和致畸性,滴滴涕則會導(dǎo)致不良的神經(jīng)系統(tǒng)影響和免疫缺陷[79].

綜上所述,MPs/NPs對水質(zhì)安全的危害主要有以下兩方面:(1)MPs/NPs將影響到生物膜上微生物菌群,例如產(chǎn)嗅菌的數(shù)量和種類,從而誘導(dǎo)產(chǎn)生種類更多、濃度更大的致嗅物,還更可能會促進潛在致病菌類群的積累[75],從而嚴重影響龍頭水的品質(zhì)及適飲性;(2)管網(wǎng)水中的有機污染物、重金屬及殘留的消毒劑等都將與MPs/NPs產(chǎn)生復(fù)合效應(yīng),主要表現(xiàn)在強大的比表面積將加速對污染物、病原體的吸附.而最初在微塑料表面吸附的污染物,當MPs/NPs被攝入并停留在人體內(nèi),由于pH值較低、溫度較高、存在消化液體等環(huán)境,生物體中吸附污染物的解吸附率比海水中快得多[80].因此MPs/NPs對水質(zhì)安全及人體的危害可能遠大于現(xiàn)有研究的結(jié)論.

4 結(jié)論與展望

4.1 結(jié)論

供水管網(wǎng)中MPs/NPs的來源主要有兩大類:第一類是由于未針對MPs/NPs去除進行專門的工藝優(yōu)化,自來水廠現(xiàn)有常規(guī)或深度處理對MPs/NPs的去除率僅為70%～80%左右,且部分水處理工藝還會使塑料碎片化,導(dǎo)致出廠水仍殘留大量的MPs/NPs;第二類是供水管網(wǎng)管道本身存在釋放可能,溫度、泵開啟產(chǎn)生的機械磨損、水流作用下的剪切力、微生物以及消毒劑等因素都會在一定程度上影響塑料管道中MPs/NPs的釋放.

MPs/NPs因自身密度、材質(zhì)、電荷等原因,在管道內(nèi)可能會發(fā)生沉積、聚集等現(xiàn)象.同時會同管網(wǎng)中有機物質(zhì)、微生物、消毒劑等物質(zhì)發(fā)生作用,出現(xiàn)MPs/NPs破裂碎化、吸附有害物質(zhì)復(fù)合作用以及改變微生物群落,產(chǎn)生應(yīng)激反應(yīng)等現(xiàn)象,從而影響供水管網(wǎng)水質(zhì)安全問題.

4.2 展望

①模擬真實環(huán)境下的飲用水管道系統(tǒng),考察不同環(huán)境下,如流速、水溫、pH值、不同塑料材質(zhì)的管材、管齡等,塑料管道中原位釋放的MPs/NPs的賦存特征(含量及粒徑分布);②明確MPs/NPs對真實環(huán)境下供水管道系統(tǒng)水質(zhì)安全問題的危害,從而采取措施保障龍頭水的安全及適飲性問題;③加強如何提高或優(yōu)化現(xiàn)有工藝針對MPs/NPs的去除效率的研究,從源頭上對MPs/NPs進行控制;④研制新材料作為供水管材或進一步提高塑料管材的穩(wěn)定性,從而防止供水管網(wǎng)MPs/NPs釋放的可能.

[1] Li J, Liu H, Paul Chen J. Microplastics in freshwater systems: A review on occurrence, environmental effects, and methods for microplastics detection [J]. Water Research, 2018,137:362-374.

[2] Cole M, Lindeque P, Halsband C, et al. Microplastics as contaminants in the marine environment: A review [J]. Marine Pollution Bulletin, 2011,62(12):2588-2597.

[3] Zhou X, Zhang K, Zhang T, et al. Biotransformation of halophenols into earthy-musty haloanisoles: Investigation of dominant bacterial contributors in drinking water distribution systems [J]. Journal of Hazardous Materials, 2021,403:123693.

[4] Qiao R, Sheng C, Lu Y, et al. Microplastics induce intestinal inflammation, oxidative stress, and disorders of metabolome and microbiome in zebrafish [J]. Science of The Total Environment, 2019,662:246-253.

[5] Yee M S, Hii L, Looi C K, et al. Impact of Microplastics and Nanoplastics on Human Health [J]. Nanomaterials, 2021,11(2):496.

[6] Xia L, Gu W, Zhang M, et al. Endocytosed nanoparticles hold endosomes and stimulate binucleated cells formation [J]. Particle and Fibre Toxicology. 2016,13(1).

[7] Zhang N, Li Y B, He H R, et al. You are what you eat: Microplastics in the feces of young men living in Beijing [J]. Science of The Total Environment, 2021,767:144345.

[8] Ragusa A, Svelato A, Santacroce C, et al. Plasticenta: First evidence of microplastics in human placenta [J]. Environment International, 2021,146:106274.

[9] Barboza L G A, Dick Vethaak A, Lavorante B R B O, et al. Marine microplastic debris: An emerging issue for food security, food safety and human health [J]. Marine Pollution Bulletin, 2018,133:336-348.

[10] Hernandez L M, Yousefi N, Tufenkji N. Are there nanoplastics in your personal care products? [J]. Environmental Science & Technology Letters, 2017,4(7):280-285.

[11] Dris R, Gasperi J, Mirande C, et al. A first overview of textile fibers, including microplastics, in indoor and outdoor environments [J]. Environmental Pollution, 2017,221:453-458.

[12] Lehner R, Weder C, Petri-Fink A, et al. Emergence of nanoplastic in the environment and possible impact on human health [J]. Environmental Science & Technology, 2019,53(4):1748-1765.

[13] Pivokonsky M, Pivokonská L, Novotná K, et al. Occurrence and fate of microplastics at two different drinking water treatment plants within a river catchment [J]. Science of the Total Environment, 2020,741: 140236.

[14] Wang Z, Lin T, Chen W. Occurrence and removal of microplastics in an advanced drinking water treatment plant (ADWTP) [J]. Science of the Total Environment, 2020,700:134520.

[15] Kosuth M, Mason S A, Wattenberg E V. Anthropogenic contamination of tap water, beer, and sea salt [J]. PLOS ONE, 2018,13(4):e194970.

[16] Shen M, Zeng Z, Wen X, et al. Presence of microplastics in drinking water from freshwater sources: the investigation in Changsha, China [J]. Environmental Science and Pollution Research, 2021,28(31): 42313-42324.

[17] Sang W, Chen Z, Mei L, et al. The abundance and characteristics of microplastics in rainwater pipelines in Wuhan, China [J]. Science of The Total Environment, 2021,755:142606.

[18] 王占杰,趙 艷,郭 晶.中國塑料管道行業(yè)“十二·五”期間發(fā)展狀況及“十三·五”期間發(fā)展建議[J]. 中國塑料, 2016,30(5):1-7.

Wang Z J, Zhao Y, Guo J. Overview of China plastic pipe industry during the twelfth-five year and its development trends during the thirteenth-five year [J]. China Plastics, 2016,30(5):1-7.

[19] Alsabri A, Al-Ghamdi S G. Carbon footprint and embodied energy of PVC, PE, and PP piping: Perspective on environmental performance [J]. Energy Reports, 2020,6:364-370.

[20] Su L, Xue Y, Li L, et al. Microplastics in Taihu Lake, China [J]. Environmental Pollution, 2016,216:711-719.

[21] Di M, Liu X, Wang W, et al. Manuscript prepared for submission to environmental toxicology and pharmacology pollution in drinking water source areas: Microplastics in the Danjiangkou Reservoir, China [J]. Environmental Toxicology and Pharmacology, 2019,65:82-89.

[22] Wu J, Zhang Y, Tang Y. Fragmentation of microplastics in the drinking water treatment process - A case study in Yangtze River region, China [J]. Science of The Total Environment, 2022,806:150545.

[23] Mintenig S M, L?der M G J, Primpke S, et al. Low numbers of microplastics detected in drinking water from ground water sources [J]. Science of The Total Environment, 2019,648:631-635.

[24] Pivokonsky M, Cermakova L, Novotna K, et al. Occurrence of microplastics in raw and treated drinking water [J]. Science of The Total Environment, 2018,643:1644-1651.

[25] Ma B, Xue W, Hu C, et al. Characteristics of microplastic removal via coagulation and ultrafiltration during drinking water treatment [J]. Chemical Engineering Journal, 2019,359:159-167.

[26] Enfrin M, Dumée L F, Lee J. Nano/microplastics in water and wastewater treatment processes – Origin, impact and potential solutions [J]. Water Research, 2019,161:621-638.

[27] Lv X, Dong Q, Zuo Z, et al. Microplastics in a municipal wastewater treatment plant: Fate, dynamic distribution, removal efficiencies, and control strategies [J]. Journal of Cleaner Production, 2019,225:579- 586.

[28] Jassim K A, Jassim W H, Mahdi S H. The effect of sunlight on medium density polyethylene Water pipes [J]. Energy Procedia, 2017,119:650-655.

[29] Sarkar D J, Das Sarkar S, Das B K, et al. Microplastics removal efficiency of drinking water treatment plant with pulse clarifier [J]. Journal of Hazardous Materials, 2021,413:125347.

[30] Pivokonsky M, Pivokonská L, Novotná K, et al. Occurrence and fate of microplastics at two different drinking water treatment plants within a river catchment [J]. Science of The Total Environment, 2020,741: 140236.

[31] Dalmau-Soler J, Ballesteros-Cano R, Boleda M R, et al. Microplastics from headwaters to tap water: occurrence and removal in a drinking water treatment plant in Barcelona Metropolitan area (Catalonia, NE Spain) [J]. Environmental Science and Pollution Research, 2021,28 (42):59462-59472.

[32] Gomiero A, ?ys?d K B, Palmas L, et al. Application of GCMS-pyrolysis to estimate the levels of microplastics in a drinking water supply system [J]. Journal of Hazardous Materials, 2021,416: 125708.

[33] Weber F, Kerpen J, Wolff S, et al. Investigation of microplastics contamination in drinking water of a German city [J]. Science of The Total Environment, 2021,755:143421.

[34] Kankanige D, Babel S. Identification of micro-plastics (MPs) in conventional tap water sourced from Thailand [J]. Journal of Engineering and Technological Sciences, 2020,52(1):95-107.

[35] Chanpiwat P, Damrongsiri S. Abundance and characteristics of microplastics in freshwater and treated tap water in Bangkok, Thailand [J]. Environmental Monitoring and Assessment, 2021,193:258.

[36] Kirstein I V, Hensel F, Gomiero A, et al. Drinking plastics? – Quantification and qualification of microplastics in drinking water distribution systems by μFTIR and Py-GCMS [J]. Water Research, 2021,188:116519.

[37] Ekvall M T, Lundqvist M, Kelpsiene E, et al. Nanoplastics formed during the mechanical breakdown of daily-use polystyrene products [J]. Nanoscale Advances, 2019,1(3):1055-1061.

[38] Liu P, Wu X, Huang H, et al. Simulation of natural aging property of microplastics in Yangtze River water samples via a rooftop exposure protocol [J]. Science of The Total Environment, 2021,785:147265.

[39] Hernandez L M, Xu E G, Larsson H C E, et al. Plastic teabags release billions of microparticles and nanoparticles into tea [J]. Environmental Science & Technology, 2019,53(21):12300-12310.

[40] Chamas A, Moon H, Zheng J, et al. Degradation Rates of Plastics in the Environment [J]. ACS Sustainable Chemistry & Engineering, 2020,8(9):3494-3511.

[41] Shi X, Ngo H H, Sang L, et al. Functional evaluation of pollutant transformation in sediment from combined sewer system [J]. Environmental Pollution, 2018,238:85-93.

[42] Mitroka S M, Smiley T D, Tanko J M, et al. Reaction mechanism for oxidation and degradation of high density polyethylene in chlorinated water [J]. Polymer degradation and stability, 2013,98(7):1369-1377.

[43] Arhant M, Le Gall M, Le Gac P, et al. Impact of hydrolytic degradation on mechanical properties of PET - Towards an understanding of microplastics formation [J]. Polymer Degradation and Stability, 2019,161:175-182.

[44] Whelton A J, Dietrich A M. Critical considerations for the accelerated ageing of high-density polyethylene potable water materials [J]. Polymer Degradation and Stability, 2009,94(7):1163-1175.

[45] Hassinen J. Deterioration of polyethylene pipes exposed to chlorinated water [J]. Polymer Degradation and Stability, 2004,84(2):261-267.

[46] Song Y K, Hong S H, Jang M, et al. Combined effects of UV exposure duration and mechanical abrasion on microplastic fragmentation by polymer type [J]. Environmental Science & Technology, 2017,51(8): 4368-4376.

[47] Koelmans A A, Mohamed Nor N H, Hermsen E, et al. Microplastics in freshwaters and drinking water: Critical review and assessment of data quality [J]. Water Research, 2019,155:410-422.

[48] Kim S, Marion M, Jeong B, et al. Crossflow membrane filtration of interacting nanoparticle suspensions [J]. Journal of Membrane Science, 2006,284(1/2):361-372.

[49] Zhu K, Jia H, Sun Y, et al. Long-term phototransformation of microplastics under simulated sunlight irradiation in aquatic environments: Roles of reactive oxygen species [J]. Water Research, 2020,173:115564.

[50] Vahidi E, Jin E, Das M, et al. Environmental life cycle analysis of pipe materials for sewer systems [J]. Sustainable Cities and Society, 2016, 27:167-174.

[51] Wu F, Pennings S C, Tong C, et al. Variation in microplastics composition at small spatial and temporal scales in a tidal flat of the Yangtze Estuary, China [J]. Science of The Total Environment, 2020, 699:134252.

[52] Zhang Z, Chen Y. Effects of microplastics on wastewater and sewage sludge treatment and their removal: A review [J]. Chemical Engineering Journal, 2020,382:122955.

[53] Madejski G R, Ahmad S D, Musgrave J, et al. Silicon nanomembrane filtration and imaging for the evaluation of microplastic entrainment along a municipal water delivery route [J]. Sustainability, 2020,12 (24):10655.

[54] 鐘 丹,袁一星,馬文成,等.供水管網(wǎng)內(nèi)生物膜與余氯衰減交互作用[J]. 哈爾濱工業(yè)大學(xué)學(xué)報, 2017,49(8):49-54.

Zhong D, Yuan Y X, Ma W C, et al. Interaction effects between biofilm and chlorine decay in water distribution network [J]. Journal of Harbin Institute of Technology, 2017,49(8):49-54.

[55] Zhang X, Xia X, Dai M, et al. Microplastic pollution and its relationship with the bacterial community in coastal sediments near Guangdong Province, South China [J]. Science of The Total Environment, 2021,760:144091.

[56] Jeong C, Won E, Kang H, et al. Microplastic size-dependent toxicity, oxidative stress induction, and p-JNK and p-p38 activation in the monogonont rotifer () [J]. Environmental Science & Technology, 2016,50(16):8849-8857.

[57] Liu X, Ma J, Yang C, et al. The toxicity effects of nano/microplastics on an antibiotic producing strain - Streptomyces coelicolor M145 [J]. Science of The Total Environment, 2021,764:142804.

[58] Liang Y, Yang X, Wang Y, et al. Influence of polystyrene microplastics on rotifer () growth, reproduction, and antioxidant responses [J]. Aquatic Ecology, 2021,55(3):1097-1111.

[59] Kik K, Bukowska B, Sicińska P. Polystyrene nanoparticles: Sources, occurrence in the environment, distribution in tissues, accumulation and toxicity to various organisms [J]. Environmental Pollution, 2020, 262:114297.

[60] Rossi G, Barnoud J, Monticelli L. Polystyrene nanoparticles perturb lipid membranes [J]. The Journal of Physical Chemistry Letters, 2014,5(1):241-246.

[61] Miao L, Hou J, You G, et al. Acute effects of nanoplastics and microplastics on periphytic biofilms depending on particle size, concentration and surface modification [J]. Environmental Pollution, 2019,255:113300.

[62] Cui R, Kim S W, An Y. Polystyrene nanoplastics inhibit reproduction and induce abnormal embryonic development in the freshwater crustacean Daphnia galeata [J]. Scientific Reports, 2017,7(1).

[63] Zhang W, Liu Z, Tang S, et al. Transcriptional response provides insights into the effect of chronic polystyrene nanoplastic exposure on Daphnia pulex [J]. Chemosphere, 2020,238:124563.

[64] Zhang K, Cao C, Zhou X, et al. Pilot investigation on formation of 2,4,6-trichloroanisole via microbial O-methylation of 2,4,6- trichlorophenol in drinking water distribution system: An insight into microbial mechanism [J]. Water Research, 2018,131:11-21.

[65] Zhou X, Zhang K, Zhang T, et al. Formation of odorant haloanisoles and variation of microorganisms during microbial O-methylation in annular reactors equipped with different coupon materials [J]. Science of The Total Environment, 2019,679:1-11.

[66] Burlingame G A, Doty R L, Dietrich A M. Humans as sensors to evaluate drinking water taste and odor: A review [J]. Journal - American Water Works Association, 2017,109(11):13-24.

[67] Dietrich A M, Burlingame G A. A review: The challenge, consensus, and confusion of describing odors and tastes in drinking water [J]. Science of The Total Environment, 2020,713:135061.

[68] 張可佳,吳小剛,吳佳佳,等.給水管網(wǎng)中硫醚類腥臭物質(zhì)的研究進展[J]. 給水排水, 2020,56(12):99-105.

Zhang K J, Wu X G, WU J J, et al. Review on sulfur odorants in drinkingwater distribution system [J]. Water & Wastewater Engineering, 2020,56(12):99-105.

[69] Cen C, Zhang K, Zhang T, et al. Algae-induced taste and odour problems at low temperatures and the cold stress response hypothesis [J]. Applied Microbiology and Biotechnology, 2020,104(21):9079- 9093.

[70] K?gel T, Bjor?y ?, Toto B, et al. Micro- and nanoplastic toxicity on aquatic life: Determining factors [J]. Science of The Total Environment, 2020,709:136050.

[71] Zettler E R, Mincer T J, Amaral-Zettler L A. Life in the “Plastisphere”: Microbial communities on plastic marine debris [J]. Environmental Science & Technology, 2013,47(13):7137-7146.

[72] Brennecke D, Duarte B, Paiva F, et al. Microplastics as vector for heavy metal contamination from the marine environment [J]. Estuarine, Coastal and Shelf Science, 2016,178:189-195.

[73] Sun C, Zhang W, Ding R, et al. Mechanism of low concentrations of polystyrene microplastics influence the cytotoxicity of Ag ions to Escherichia coli [J]. Chemosphere, 2020,253:126705.

[74] Zhu D, An X, Chen Q, et al. Antibiotics disturb the microbiome and increase the incidence of resistance genes in the gut of a common soil collembolan [J]. Environmental Science & Technology, 2018, 52(5):3081-3090.

[75] Goraj W, Pytlak A, Kowalska B, et al. Influence of pipe material on biofilm microbial communities found in drinking water supply system [J]. Environmental Research, 2021,196:110433.

[76] Wang F, Wong C S, Chen D, et al. Interaction of toxic chemicals with microplastics: A critical review [J]. Water Research, 2018,139:208- 219.

[77] Kelkar V P, Rolsky C B, Pant A, et al. Chemical and physical changes of microplastics during sterilization by chlorination [J]. Water Research, 2019,163:114871.

[78] Wang F, Zhang M, Sha W, et al. Sorption behavior and mechanisms of organic contaminants to nano and microplastics [J]. Molecules, 2020, 25(8):1827.

[79] Mansouri A, Cregut M, Abbes C, et al. The environmental issues of DDT pollution and bioremediation: A multidisciplinary review [J]. Applied Biochemistry and Biotechnology, 2017,181(1):309-339.

[80] Bakir A, Rowland S J, Thompson R C. Enhanced desorption of persistent organic pollutants from microplastics under simulated physiological conditions [J]. Environmental Pollution, 2014,185:16- 23.

The abundance and contamination characteristics of micro/nano-plastics in drinking water distribution systems.

ZHENG Ying-ying, ZHANG Ke-jia*, CEN Cheng, MAO Ru-yin, ZHANG Tu-qiao

(College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China)., 2022,42(4)：1610～1617

Micro/nano-plastics are becoming a research hotspot due to the characteristics of wide distribution, small particle size, difficulty in degradation, and can adsorb toxic substances, etc. However, the information on the status of environmental contamination and removal is rare. In this review, the research status of micro/nano-plastics in drinking water distribution systems (DWDS) was discussed, which was from the perspectives of the sources, migration characteristics and safety hazards of water quality. The results showed that residual micro/nano-plastics can be carried into DWDS by the effluent of water treatment plants. Besides, pipe material, flow velocity, mechanical wear and residual chlorine may affect the release of micro/nano-plastics. The spatial and temporal variation of micro/nano-plastics was affected by the inherent characteristics (e.g., density and charge) in DWDS. In the process of drinking water transmission and distribution, the water quality and safety of the DWDS has been considered that is relevant to the reaction between micro/nano-plastics with organics, microorganisms and other substances. Therefore, the review makes a prospect for the future research direction, in order to provide theory basis for further understanding of the impact of micro/nano-plastics on the drinking water safety, in addition to the control of micro/nano-plastics.

micro/nanoplastics；drinking water distribution system；abundance characteristics；water quality safety

X131.2

A

1000-6923(2022)04-1610-08

鄭瑩瑩(1998-),女,浙江溫州人,浙江大學(xué)碩士研究生,主要研究方向為供水管網(wǎng)水質(zhì)安全保障.發(fā)表文章4篇.

2021-09-30

國家自然科學(xué)基金資助項目(51978602,51778561)

*責(zé)任作者, 副教授, zhangkj@zju.edu.cn