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塑料制品因其轻便、耐用而在日常生活中广泛使用。常使用的塑料制品化学种类主要包括：聚乙烯（PE）、聚丙烯（PP）、聚苯乙烯（PS）、聚对苯二甲酸乙二醇酯（PET）、聚氯乙烯（PVC）、聚碳酸酯（PC）、聚酰胺（PA）、聚丙烯腈（PAN）和聚氨酯（PU）。截至2019年，全球塑料产量已达3.7亿吨[1]。然而，对于塑料制品缺乏相应的回收利用手段，由此产生的塑料垃圾占总固体废弃物的60%—80%[2]。这些塑料垃圾长期在冲刷、腐蚀和光照等物理、化学作用下被分解为更小的塑料碎片或颗粒，当其尺寸小于5 mm时即可定义为微塑料（microplastics，MPs）。根据估算，全球海洋中至少漂浮着5.25万亿颗微塑料，重量在26.9万吨以上[3]。除海洋以外，微塑料还出现在世界各地的河流与湖泊[4]，甚至极地环境中[5]。环境中散布的微塑料易被生物体摄入，造成一系列负面效应，包括生长速度减缓、病理应激、氧化应激和引起生殖障碍等[6-7]。微塑料引发的污染问题近年来已成为全球生态与环境科学的研究热点之一。
环境中的微塑料很少以塑料原生形态存在，而是受光照、高温、生物膜以及物理磨损等因素老化。老化引起微塑料表面和结构特征的改变，从而影响微塑料在环境中的命运。如，老化引起微塑料表面含氧官能团和亲水性的增加，增加其对于部分有机污染物和重金属的吸附能力，同时促进了微塑料在土壤和水体中的运移能力[8-10]，增加浮游动物或贻贝对其的摄入与积累[11-12]。此外，老化影响微塑料的结晶度和机械强度，导致微塑料基质裂解产生更多的亚微塑料甚至纳米级微塑料，纳米级微塑料可以进入血液循环从而到达消化系统以外的其他器官[13-14]。老化也会导致微塑料中内源污染物–添加剂（增塑剂、阻燃剂、抗氧化剂等）或基质中低聚物、小分子化合物向环境的释放。许多研究表明老化微塑料浸出液比原始微塑料浸出液更易引发生物体内分泌紊乱、致死、胚胎畸形或死亡等毒性作用[15-17]。
在引起微塑料老化的众多因素中，光照引发的老化最为快速和剧烈[18-19]，采用光照辐射模拟老化的微塑料与环境微塑料相关性较好，因此光老化是目前用于模拟微塑料老化的主流手段（66.7%）[20]。在此，本文综述了光老化微塑料表面与结构特征的改变，环境共存组分在微塑料光老化过程中的作用及携带内源污染物的释放与降解，以期为微塑料的环境行为研究及毒性风险评估提供参考。
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光老化会引起微塑料表面泛黄变色，颜色加深。这主要是微塑料光老化过程中形成的不饱和键，例如塑料中酚类稳定剂氧化形成醌类化合物[21]，或PVC塑料光氧化脱HCl形成共轭不饱和键所导致[18, 22]。在微观层面，光老化影响微塑料的表面粗糙度。大部分光老化微塑料表面凹凸不平，形成（1） 凸起的薄片或结节，（2） 裂纹，（3） 裂缝[23-28]。由于光和氧的穿透能力有限，光氧引起的微塑料表面侵蚀是（1）和（2）的主要原因。当受外部机械力作用如水流、海砂的摩擦，或水分导致的微塑料内外溶胀不均，便会引起次级颗粒或碎片从微塑料表面的剥落[18]。Halle等发现，水环境中球状微塑料比扁平状微塑料接受光照面积更大，因此能形成更多的裂纹，剥落的亚微塑料数量更多[29]。（3）的产生主要针对半结晶塑料（PE、PP等）[18]。由于非晶相区域老化速率快于晶相区，裂缝于晶间区域产生，平行于聚合物主链线性排列方向生长[30]。机械力、水以及聚合物主链排列方向影响裂缝生长。随着裂缝扩散至内层，微塑料产生断裂形成纤维状亚微塑料[31-32]。
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光老化后的微塑料倾向于粒径降低，生成一系列微米级甚至纳米级的亚微塑料。识别光老化微塑料产生的亚微塑料至关重要，因为它们极有可能跨越生物屏障，具有更大的潜在毒性。由于技术手段的限制，大部分野外调查仅能对300 μm以上的微塑料进行量化。有研究对PS立方体进行了模拟光老化，研究结果显示产生了粒径为60—500 μm的塑料颗粒，粒径峰值集中在2.03—2.88 μm和138—189 nm。随着粒径的减小，微塑料比表面积势必会增加，但目前缺乏关于纳米塑料比表面积的研究。102 μm级微塑料比表面积文献报道值在100 m2·g−1左右[33-34]，10 μm级微塑料比表面积文献报道值在101 m2·g−1左右[35-36]。由于光老化并未增加微塑料内部的孔道，微塑料比表面积增加较少（+0.5%—68%）[33-36]。假设其产生的纳米塑料均为微球，102 nm级纳米塑料比表面积推测在102 m2·g−1左右。从产生亚微塑料的数量上来看，经过一年日光暴露，单位质量微塑料产生的微米级亚微塑料数量在104—105个·g−1，纳米塑料为1010个·g−1，占原始微塑料质量的0.01%和0.1%[37]。而在不同文献报道中，单位面积微塑料产生的微米级亚微塑料数量级在106—107 个·cm−2，纳米塑料为107—108 个·cm−2[38-39]。
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无论自然环境中的光老化微塑料，还是室内模拟的光老化微塑料，均通过傅里叶变换红外（FTIR）光谱仪检测到其表面含氧官能团的增加[40-41]，包括羟基（O─H）（3100—3700 cm−1）、羰基（C═O）（1690—1810 cm−1）和碳氧（C─O）（1200—1280 cm−1）[23, 42-43]。采用羰基指数（carbonyl index，CI），即羰基部分的红外光谱峰强相比于参考峰峰强的比值，以评估微塑料的光老化程度。对于不同化学种类微塑料，通常选择随老化程度变化不大的特征峰作为参考峰，如PE （2908—2920 cm−1），PP （2885—2940 cm−1）和PS （1452 cm−1）[42-43]。研究发现东京海滩上的树脂颗粒羰基指数范围为0.00—0.89[44]，印度泰米尔纳德邦沙滩上PE微塑料羰基指数范围为0.07—0.70，PP微塑料羰基指数范围为0.20—3.30[41]。Brandon等对比了实验室光老化，以及从加利福尼亚洋流、北太平洋亚热带环流收集的微塑料颗粒羰基指数，发现通过羰基指数估算的微塑料老化时间与海洋环流时间一致。以上结果说明羰基指数能较好地预测微塑料在环境中暴露老化的时间[42]。除羰基指数，采用X射线光电子能谱分析（XPS）和扫描电镜能谱（SEM–EDS）分析O/C比是评估微塑料光老化程度另一重要指标[25]。与FTIR相比，XPS与SEM–EDS表征微塑料表层（nm厚度）老化状况，因此对微塑料的早期老化更敏感。另外，O/C包含除羰基以外的羟基和碳氧，反映了微塑料的总体氧化状况。
光老化微塑料表面含氧官能团的增加会引发微塑料疏水性的降低。一些研究通过表面接触角测量法发现光老化微塑料表面疏水性大约下降15%—55%[26, 43, 45]。因此，观察到光老化微塑料对于疏水性化合物包括双酚A[46]，2,2',4,4'-四溴二苯醚[47]，9-硝基蒽[48]及一些脂肪烃和芳香族化合物[34]吸附的降低。同时，由于含氧官能团的增多，促进了光老化微塑料与污染物之间的离子交换、氢键作用和静电相互作用，对于金属离子Cu2+、Zn2+ [49]、Pb2+ [50]、Cd2+ [51]，药物类环丙沙星[43, 52]、氨氯地平[45]、阿莫西林[53]和农药（多菌灵、除虫脲、马拉硫磷、苯醚甲环唑）[54]的吸附能力增强。光老化微塑料含氧官能团变化对于光老化微塑料环境行为的另一重要影响即团聚性和迁移能力的改变。大多数情况下，光老化过程会使微塑料的团聚行为减弱，这主要是由于以下原因：（1） 微塑料之间的范德华吸引力减弱；（2） 微塑料上的含氧官能团去质子化，ζ电位下降，静电斥力增强；（3） 光老化过程中释放有机物引起的微塑料之间空间位阻[55-56]。目前仅发现Ca2+离子可通过与光老化微塑料表面羧基之间的桥联作用促进微塑料的团聚[56]。总体而言，光老化降低了微塑料的团聚，这不仅增加了微塑料在环境中的迁移能力，也提高了其携带的污染物在环境中远距离传输的能力[8-9]，增加了微塑料的生态风险。
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根据聚合物中高分子链的堆叠状态，聚合物可分为结晶态和非结晶态。结晶态指高分子链伸直且平行紧密排列，形成结晶学中的“密堆叠”。而非结晶态指聚合物链段的堆叠不形成任何有序结构，分子链构象呈无规则线团状及相互贯穿[57]。光老化往往会引起聚合物结晶部分所占比例—即结晶度明显地上升（4%—10%）[47, 58]。这是由于光老化造成的降解优先从分子链排列松散的非结晶区开始。随后，非结晶区原先缠绕的分子链因断链得以释放，进而重排发生二次化学结晶[59-61]。X射线衍射仪（XRD）的表征结果显示，光老化期间增加的晶体不产生新的晶型，而与初始晶体以相同方向生长。当聚合物的结晶度达到一定程度便不再增加，因为羰基、羧基等缺陷位会阻止分子链继续结晶[59]。尽管光老化使微塑料结晶度提高，微塑料晶体结构的整体秩序变得更加无序。Garvey等采用小角和广角X射线衍射法检查PE分子链在半结晶片层中的堆叠，发现光老化PE微塑料的晶体片层厚度无明显变化，而晶体片层长度明显降低[62]。光老化微塑料晶体结构的变化会极大地影响聚合物的机械稳定性以及随后的降解。
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微塑料光老化的本质为聚合物吸收日光中的紫外辐射（UV）发生的自由基反应，其步骤概括如下[63]：
链引发 Intiator→R•
吸附分子氧 R•+O2→ROO•
链增长 ROO•+RH→ROOH+R•
ROOH→RO•+•OH
次级反应 RO•→酮类、醇类、羧基类、酯类、过氧化物、断链反应（β裂解）
链终止 2R•→R─R
R•+ROO•→ROOR
具体来说，在初始阶段聚合物吸收紫外辐射引发链反应，产生自由基。在链增长阶段，之前的自由基与分子氧形成过氧自由基（ROO•），过氧自由基从周围环境夺取氢原子，形成中间体氢过氧化物（ROOH）[19, 64]。氢过氧化物中O─O键在紫外线下不稳定，断裂形成烷氧基自由基（RO•）及羟基自由基（•OH）。烷氧基自由基是链反应中的重要中间体，它可以通过夺氢、断链、重排继续反应形成醇、酮和醛等产物。最终，自由基之间发生反应，或链端烯烃与烷烃间发生歧化反应形成稳定产物，即链终止。最近有研究表明，一些含丰富共轭苯环结构的微塑料，如PS和酚醛树脂，在光老化过程中形成可以长期存在的离域稳定自由基，即环境持久性自由基（environmentally persistent free radicals，EPFRs）[65]。这些EPFRs诱导产生的活性氧自由基（reactive oxygen species，ROS）包括
${\rm{O}}_2^- $ ，1O2，H2O2和•OH，快速促进微塑料的进一步老化[66]。与一般塑料制品相同，氧气和高温是同样也是促进微塑料光老化的重要因素[18]。水对于微塑料光老化有两方面的作用，首先水可以作为提供•OH的介质，促进微塑料的光老化，微塑料的光老化速率随•OH接触面积增大而增加[67-68]。并且，水的供氢能力强于空气，因此微塑料在水中优先形成羟基，在空气中优先生成羰基[43, 64]。另一方面，水降低了UV利用率和环境温度，减缓微塑料的光老化[64]。微塑料作为一种新型污染物，与塑料制品相比粒径更小，比表面积更大，出现的环境领域更广泛，因此其光老化过程将受更复杂环境因素的影响。影响污染物光化学反应过程的环境共存组分一般包括天然有机质（NOM）、
${\rm{CO}}_3^{2-} $ 、NO3−、Cl−、Br−、Fe3+及其配合物，金属氧化物等，它们可以调节活性中间体的产生与猝灭，及竞争光吸收，对微塑料的光老化有截然不同的影响。表1总结了现有的环境共存组分对微塑料光老化影响的报道。以NOM为例，NOM可能产生活性中间体–激发态NOM（3NOM*），ROS（1O2、•OH、${\rm{O}}_2^{\cdot-}$ ）和水合电子，通过敏化光解、光氧化降解和光还原降解促进光化学反应[69]。同时，NOM也有可能因为光屏蔽效应或猝灭活性中间体，阻碍光化学反应[70]。目前的研究显示，水中可溶性有机质和土壤有机质对于微塑料光老化分别有相反的作用，具体影响机制与NOM分子结构（芳香基团、双键、脂肪族及氮硫杂原子）及浓度有关[43, 71-72]。卤素离子（Cl−/Br−）是海洋与河口水环境中的重要离子。卤素离子可以猝灭活性中间体，产生具有很高反应活性的卤素自由基。然而卤素自由基的对不同污染物的反应活性差异较大。针对微塑料的研究显示，Cl−是海水对微塑料光老化起抑制作用的主要原因[71]。实际环境是多种组分共存的复杂体系，各组分之间可能相互影响相互叠加，对微塑料的光老化产生更为复杂的影响。 -
为了改善塑料的性能或赋予其功能，塑料中往往掺杂各种添加剂。使用量较大的添加剂包括填充剂，增塑剂和阻燃剂，其含量分别在0—50%，10%—70%和10%—20%[75-76]。其余使用频繁而常见的添加剂包括抗氧化剂、紫外吸收剂和着色剂。大多数添加剂采用物理掺杂的方式被添加到塑料中，与塑料间缺乏化学键，因此添加剂极易释放进入环境中[77]。以塑料中添加剂向水相的释放为例，其过程可以分为两个步骤：（1） 聚合物表面的添加剂向水相的快速释放；（2） 聚合物内部添加剂向聚合物表面的缓慢扩散。其中，步骤（1）的释放驱动力主要受添加剂在聚合物与水的固液界面分配能力的影响，即添加剂的疏水性（KOW）或溶解度而非添加剂分子尺寸[78]。而步骤（2）中添加剂的缓慢释放则主要受聚合物晶体性质的影响[78-80]。因此分子链处于无规则排列的非结晶态比紧密堆叠的结晶态更利于添加剂在聚合物中的扩散。另外，当环境温度高于聚合物的玻璃化转化温度（Tg）时，非结晶区分子链处于橡胶态，即分子链能进行链段运动从而形成“自由体积”，添加剂分子有足够的自由空间进行扩散。因此，在处于橡胶态的聚合物中，添加剂的扩散速率更快[81]。在给定温度下，具有较低Tg值的聚合物链段迁移性更强，所包裹的添加剂也更易扩散[78-79]。
对于稳定的塑料基质而言，添加剂在聚合物中的扩散缓慢，释放通量极低，理论上微塑料中的添加剂不会对环境和生态系统构成重大风险。以多溴联苯醚为例，半径为0.5 mm的丙烯腈-丁二烯-苯乙烯（ABS）微塑料中的低溴联苯醚的扩散半衰期为几百到几十万年，而高溴联苯醚的扩散半衰期为几万到几十亿年[79]。然而，光老化会引起微塑料粒径减少，微塑料平均分子量降低，基质稳定性降低甚至裂解。当微塑料粒径减小3个数量级时，微塑料颗粒总数增加至9个数量级，释放半衰期减少6个数量级，添加剂释放的可能性提高[75]。针对光老化微塑料中添加剂的释放行为目前主要采用溶液浸出法进行研究（表2）。大部分情况下，光老化均促进了微塑料中添加剂的释放速率与释放通量。值得指出的是，不同研究的实验条件差异较大，例如采用含添加剂的商业微塑料或纯聚合物微塑料，在固定体积溶液中的浸出或在开放水域的浸出，不能直接对所获得动力学结果进行比较。并且，许多研究缺少光老化微塑料吸收光照辐射总量的数据，无法根据平均日照当量求得该实验等同的日照时长。因此，目前释放实验获得的数据或结果无法对建立预测光老化微塑料添加剂释放行为的相关模型提供依据，而这类模型对于定量评估微塑料添加剂对环境和生态系统的影响是十分必要的。尽管现有的研究揭示了微塑料中添加剂的释放速率主要与微塑料结晶度有关。但对于成分复杂的商业微塑料，稳定剂的存在会减缓商业微塑料光老化，而塑化剂或填充剂的存在是否会影响添加剂逸出的扩散路径仍未知。后续的研究应考虑多种添加剂共存时添加剂的释放行为。
光老化过程中微塑料内添加剂除了以掺杂的原始形态释放，也可以被微塑料敏化而降解释放。Khaled等发现，十溴联苯醚在PS塑料中的光降解速率快于它在纤维素和在PET塑料中的光降解速率[82]。作者进一步通过比较溴系阻燃剂在四氢呋喃和PS塑料中的量子产率，发现溴系阻燃剂在PS塑料中量子产率大于在四氢呋喃中[83]。这是可能是因为PS含丰富共轭苯环结构，光老化过程中容易产生1O2和3PS*引起添加剂的降解。并且，随着PS光老化程度加深，PS表面含氧生色团增多，更易引发自由基反应[84]。也有研究报道了光老化PVC微塑料中有机锡的降解释放，这主要是由于PVC塑料生产过程中残留的杂质（过氧化物交联剂）产生•OH引起有机锡降解[85]。
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微塑料的光老化会造成聚合物主链的断裂，形成一系列分子大小不同的断链产物。表3总结了微塑料光老化过程中释放的断链产物特征。Garvey等分析了可以用网筛法（>300 μm）采集到的102 μm级PE微塑料，其数均分子量大约在0.94—5.2 kDa，─C2H4─单体长度为34—186。而PE塑料制品分子量约在10.8—29.3 kDa，─C2H4─单体长度为386—1046[62]。Ceccarini等采用有机溶剂提取了浮选法无法获得的微纳级微塑料及其相关降解产物，发现其分子量范围为0.2—1.4 kDa[63]。微塑料断链产物的水溶性部分又被称为微塑料可溶性有机碳（DOC），与天然水体中的可溶性有机质具有类似的荧光特征–即在腐殖质区域的吸收（λEx/λEm=250—400 nm/300—500 nm）[68, 91-92]。在分子量方面，微塑料DOC分子量以低于0.35 kDa的为主，而水生溶解性有机质以1 kDa左右为主[93]。通过质谱对微塑料DOC分子结构进行解析，结果显示微塑料DOC主要为加羧基或加羟基的低聚物或聚合物单体（表3）。光老化微塑料也会释放分子量更低的挥发性有机物（VOCs），如短链羧酸、酮、醛、醇、酯、内酯、芳香化合物[94-95]。聚合物主链化学稳定性是影响释放VOCs种类、含量以及VOCs分子量大小的主要因素。另外，掺杂的添加剂同样也会参与微塑料的光化学反应，改变断链产物的种类与数量。例如，含溴系阻燃剂PS微塑料光老化的断链产物产生溴化芳香族化合物及一些小分子含溴产物[96]。而含TiO2 PE微塑料光老化释放的DOC，氧化程度更低，分子量更高，其H/C和O/C比值范围窄于纯PE释放的低聚物[97]。
根据Lee等的计算，接受日照14 d后，PE、PP微塑料产生的DOC约占自身质量的3.2%[93]。Romera-Castillo也指出，全球每年从海洋塑料中浸出的DOC多达两万公吨[98]。这说明随着塑料基质的裂解，无论是微塑料DOC的产生速率或总量，都可能高于过去人们对此的预估。微塑料DOC对微生物群落结构[98-99]，或是在消毒副产物的产生方面都有重要的作用[93, 100]。目前对微塑料DOC的研究主要通过在实验室对纯聚合物进行模拟光老化，对含典型添加剂微塑料释放的DOC及环境中的老化微塑料DOC的报道还不够。这主要是因为对微塑料DOC的研究手段还较为单一，大部分研究在微塑料DOC的定性识别方面仅能确认DOC分子量及一些聚合物单体或二聚体的氧化产物。微塑料DOC是均一性较差的复杂混合物，可借用天然有机质的方法学以丰富微塑料DOC的表征手段。
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环境微塑料受光照、高温、生物膜以及物理磨损等因素老化，光老化往往是引发微塑料老化过程的第一步，也是影响微塑料老化最重要的因素。微塑料的光老化始于自由基链反应，引发分子链的断裂、交联，引起微塑料结晶度的增加，从而使微塑料机械稳定性降低，产生粒径更小的亚微塑料。以NOM、卤素离子等在内的环境共存组分可以通过活性中间体的诱导或猝灭及对光的竞争吸收影响微塑料的光老化。光老化过程中由于塑料基质的裂解，促进了微塑料内掺杂的添加剂及断链产物的释放降解，添加剂与微塑料主链分子也在光化学反应中的相互作用产生新的产物。
鉴于微塑料光老化过程中的机制复杂性，并对其他环境污染物可能产生协同影响，目前对微塑料光老化的研究正逐步受到环境、地球化学、生理、生态等各学科领域重视，有若干难点问题有待进一步研究解决。
（1） 对环境条件下（机械力、离子、天然有机质及生物膜等）微塑料的协同老化及其后续的环境行为研究不足。目前研究所使用的微塑料以塑料微珠为主，而真实环境中不同条件协同老化后的微塑料形状、异构性及氧化还原电位等可能与纯水体系中的光老化微塑料存在差异，由此造成研究结果与现实中微塑料环境归趋之间的偏差，应在相关试验设计中予以考虑。
（2） 自然环境中的微塑料很少以纯聚合物的形式存在，所包含的多种添加剂可能吸收或屏蔽光照从而对微塑料的光老化速率和产物造成影响。尤其近期随着微塑料表面环境持久性自由基的发现，推测微塑料与添加剂可能对彼此的光转化路径发挥作用，其产物释放可能对生物产生毒性。因此，有必要对微塑料光老化过程中释放的污染物开展非靶向筛查，探讨微塑料光老化过程与添加剂释放、降解的耦合机制。由于释放产物浓度较低，相关研究可能需借助在线浓缩富集装置与监测仪器的联用以开展。并且，对释放的内源污染物进行毒理学检验，以进一步研究环境微塑料老化与内源污染物的协同效应，准确评估生态毒性风险，为开发更环保、稳定的塑料制品提供依据。
微塑料的光老化过程及其携带内源污染物释放的研究进展
Research progress on photo-aging of microplastics and their effects on the release of endogenous pollutants
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摘要: 微塑料的环境行为与生态效应倍受社会关注。环境微塑料受光照、高温、生物膜以及物理磨损等因素而老化，影响其环境行为与命运。其中，光照是影响微塑料老化最重要的因素。光照引起自由基链式反应，增加聚合物分子链上的含氧官能团，引起分子链断链、交联，改变微塑料的结晶度，降低微塑料机械稳定性，造成亚微塑料的剥落和微塑料基质的破裂。本文阐述了微塑料的光老化过程中微塑料表面形貌、粒径、含氧官能团和晶体结构等物理化学性质的改变，微塑料光老化机制及常见环境共存组分的影响。同时总结了伴随塑料基质裂解，微塑料中内源污染物–即掺杂的添加剂及断链反应形成的断链产物的释放与降解，在此基础上对微塑料光老化后续研究中重点应关注的问题进行了展望。Abstract: The environmental behaviors and ecological effects of microplastics have received a lot of attention in public. Environmental microplastics were subject to aging by sunlight, high temperature, biofilm and physical stress, which affect their behaviors and fate in environment. However, sunlight was the most influence factor of microplastics aging. Sunlight could induce free-radical chain reactions, which resulted in increase of oxygen functional groups on polymer, scission and cross-linking of molecular chains, and changing the crystallinity of microplastics. The alteration of crystallinity led to embrittlement and mechanical instability of microplastics, then followed by the degradation of the polymer matrix and flaking of sub-microplastics. This review elaborated the variations of physicochemical properties including surface morphology, particle size, oxygen functional groups, crystal structure, the mechanisms and the effects of coexisting constituents in environments on microplastics photo-aging. We also summarized the release and degradation of endogenous contaminants in microplastics, i.e., doped additives and products from chain-scission degradation of plastic matrix. Finally, potential research directions about microplastics photo-aging in the future were proposed.
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Key words:
- microplastics /
- photo-aging /
- mechanism /
- endogenous pollutants /
- release
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表 1 环境典型共存组分对于微塑料光老化的影响
Table 1. The effects of typical coexisting constituents in environments on microplastics photo-aging
环境场景
Environmental scenarios环境共存组分
Coexisting constituents in environments影响示例
Examples影响机理
Mechanisms参考文献
References天然水体 可溶性有机质 + 3NOM*，ROS或水合电子 [43, 71] 土壤 土壤有机质 – 光屏蔽或猝灭中间体 [72] 海水 Cl− – 猝灭HO2•，防止其形成 ${\rm{O}}_2^{\cdot-} $ [71] 土壤 黏土、氧化铁、二氧化锰 + 催化 [72] 雨水、雾 多羧基有机酸–Fe3+配合物 + 产生 ${\rm{CO}}_2^{\cdot-}$ [73] 焦化废水、畜牧废水 吲哚类化合物 + 水合电子 ${\rm{e}}_{\rm{aq}}^- $ [74] +/–：促进/抑制微塑料光老化. +/–：Accelerate/inhibit the photo-aging of microplastics 
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表 2 光老化过程中微塑料中添加剂的释放
Table 2. The release of additives in microplastics during photo-aging
微塑料化学种类
Chemical types of microplastics添加剂
Additives光老化过程中添加剂的释放
The release of additives during photo-aging参考文献
ReferencePE 铬酸铅颜料 光老化条件下铬（Cr）和铅（Pb）的释放量增加为2—3倍。 [86] PE TiO2颗粒 光老化使微塑料释放TiO2颗粒的平衡时间由72 h减少至12 h，平衡后释放TiO2颗粒从70×105 个·L−1增加到1081.5×105个·L−1。此外，光老化微塑料释放的TiO2颗粒粒径更大。 [87] PP 硫硒化镉颜料 与原始微塑料相比，光老化微塑料对镉（Cd）的释放十分显著。 [88] 发泡PS 六溴环十二烷 释放率从37%增加到61%。 [80] PVC，PE 邻苯二甲酸酯（PAEs） 光老化PVC对PAEs的释放量增加两倍，而光老化对PE释放PAEs则无显著影响。 [89] 发泡PU 3,3'-二氨基苯胺类似物荧光剂 原始微塑料中几乎无荧光剂浸出，而光老化微塑料明显有荧光剂浸出。 [90] PS 溴系阻燃剂：十溴联苯醚、四溴双酚A、四溴双酚A–双（2,3-二溴烯丙基）醚和四溴双酚A–双（烯丙基醚） 脱溴、溴取代产物，及醚键断裂产物。 [83] PVC 有机锡 二甲基锡、单甲基锡、二丁基锡和单丁基锡 [85]
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表 3 光老化微塑料释放断链产物类型及其特征
Table 3. Chain scission products and release profiles from photo-aging of microplastics
微塑料化学种类
Chemical types of microplastics断链产物
Chain scission products断链产物特征
Release profiles of chain scission products参考文献
ReferencePE PE多聚体 分子量：0.94—5.2 kDa，碳链长度：34—186 [62] 聚烯烃和PS 氧化聚烯烃和PS多聚体或低聚物 分子量：0.2—1.4 kDa [63] PS PS单体，PS二聚体和PS三聚体 释放浓度：苯乙烯三聚体>苯乙烯二聚体>苯乙烯单体 [101-102] PE、PP DOC 79%—86 %为低分子中性物质（< 0.35k Da） [93] 含TiO2的商品PE
以及纯PEDOC 含TiO2的商品PE：H/C：1—2，O/C：0.1—0.9
含纯PE：H/C：0.7—1.9，O/C：0.2—0.5
不同TiO2 PE微塑料释放低聚物之间的相似程度高于纯PE[97] PS DOC、CO2 [68, 103] PE，PP，PS和PET PE：二羧酸同源序列化合物CxH2x–2O4 （x=8─12，14和20）；
PP：二羧酸同源序列化合物CxH2x–2O4 （x=8，11─14），无法与PE断链产物区分；
PS：3-（3-羟基苯基）丙酸及3-苯基-戊二酸的同源序列化合物；
PET：对苯二甲酸、C17H14O6、C10H10O5、C9H8O3四类同源序列化合物；两端加羧基或一端加羧基一端加羟基的聚合物单体或低聚物 [104] PA，PET PA：n-丁基丙烯酰胺等四种烷基酰胺；
PET：2-羟乙基苯甲酸酯、对苯二甲酸、4-乙酰基苯甲酸、苯甲酸、对甲基苯甲酸、苯甲酸乙烯酯、二乙二醇二苯甲酸酯、
4-乙基苯甲酸PA断链产物为烷基酰胺
PET断链产物为C─C或C─O单键断裂形成的苯甲酸盐，及重排形成的对甲基苯甲酸和4-乙基苯甲酸[105] PC 苯酚、对苯二酚、对羟基苯甲酸和对羟基苯甲醛，双酚A、PC二聚体及PC三聚体衍生化合物
（含羟基、羧基、酮、醛端）[92] PA，PET，PAN PA：2-甲基-2-丁烯醛
PET：苯甲酰肼，苯甲酸甲酯，苯甲酸，对甲基苯甲酸，对甲基苯甲酸乙酯
PAN：无[106] PP、PE、PS和PET 挥发性短链羧酸、酮、醛、醇、酯、内酯、芳香化合物 PP和PE：酮>羧酸、内酯、酯>>醇、醛
PS：酮>
醛>酸、酯、醇、芳香化合物
PET：少量酮、芳香化合物、醛和醇[94-95] 含溴系阻燃剂的PS 含羰基的溴化芳香族化合物，及溴乙烷、二溴甲烷、溴仿、溴乙醇和溴苯酚等小分子溴化产物。 [96]
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[1] EUROPE P. Plastics – The facts 2020 [EB/OL]. [2021-10-01] 2020. https://www.plasticseurope.org/en/resources/market-data [2] DERRAIK J G B. The pollution of the marine environment by plastic debris: A review [J]. Marine Pollution Bulletin, 2002, 44(9): 842-852. doi: 10.1016/S0025-326X(02)00220-5 [3] ERIKSEN M, LEBRETON L C M, CARSON H S, et al. Plastic pollution in the world's oceans: More than 5 trillion plastic pieces weighing over 250, 000 tons afloat at sea [J]. PLoS One, 2014, 9(12): e111913. doi: 10.1371/journal.pone.0111913 [4] LI J Y, LIU H H, CHEN J P. Microplastics in freshwater systems: A review on occurrence, environmental effects, and methods for microplastics detection [J]. Water Research, 2018, 137: 362-374. doi: 10.1016/j.watres.2017.12.056 [5] KANHAI L D K, GÅRDFELDT K, LYASHEVSKA O, et al. Microplastics in sub-surface waters of the Arctic Central Basin [J]. Marine Pollution Bulletin, 2018, 130: 8-18. doi: 10.1016/j.marpolbul.2018.03.011 [6] WRIGHT S L, THOMPSON R C, GALLOWAY T S. The physical impacts of microplastics on marine organisms: A review [J]. Environmental Pollution, 2013, 178: 483-492. doi: 10.1016/j.envpol.2013.02.031 [7] WANG T, WANG L, CHEN Q Q, et al. Interactions between microplastics and organic pollutants: Effects on toxicity, bioaccumulation, degradation, and transport [J]. Science of the Total Environment, 2020, 748: 142427. doi: 10.1016/j.scitotenv.2020.142427 [8] LIU J, ZHANG T, TIAN L L, et al. Aging significantly affects mobility and contaminant-mobilizing ability of nanoplastics in saturated loamy sand [J]. Environmental Science & Technology, 2019, 53(10): 5805-5815. [9] YAN X Y, YANG X Y, TANG Z, et al. Downward transport of naturally-aged light microplastics in natural loamy sand and the implication to the dissemination of antibiotic resistance genes [J]. Environmental Pollution, 2020, 262: 114270. doi: 10.1016/j.envpol.2020.114270 [10] KOOI M, NES E H V, SCHEFFER M, et al. Ups and downs in the ocean: Effects of biofouling on vertical transport of microplastics [J]. Environmental Science & Technology, 2017, 51(14): 7963-7971. [11] HARIHARAN G, PURVAJA R, ANANDAVELU I, et al. Accumulation and ecotoxicological risk of weathered polyethylene (wPE) microplastics on green mussel (Perna viridis) [J]. Ecotoxicology and Environmental Safety, 2021, 208: 111765. doi: 10.1016/j.ecoenv.2020.111765 [12] VROOM R J E, KOELMANS A A, BESSELING E, et al. Aging of microplastics promotes their ingestion by marine zooplankton [J]. Environmental Pollution, 2017, 231: 987-996. doi: 10.1016/j.envpol.2017.08.088 [13] RAGUSA A, SVELATO A, SANTACROCE C, et al. Plasticenta: First evidence of microplastics in human placenta [J]. Environment International, 2021, 146: 106274. doi: 10.1016/j.envint.2020.106274 [14] LU Y F, ZHANG Y, DENG Y F, et al. Uptake and accumulation of polystyrene microplastics in zebrafish (Danio rerio) and toxic effects in liver [J]. Environmental Science & Technology, 2016, 50(7): 4054-4060. [15] BEJGARN S, MACLEOD M, BOGDAL C, et al. Toxicity of leachate from weathering plastics: An exploratory screening study with Nitocra spinipes [J]. Chemosphere, 2015, 132: 114-119. doi: 10.1016/j.chemosphere.2015.03.010 [16] ROCHMAN C M, KUROBE T, FLORES I, et al. Early warning signs of endocrine disruption in adult fish from the ingestion of polyethylene with and without sorbed chemical pollutants from the marine environment [J]. Science of the Total Environment, 2014, 493: 656-661. doi: 10.1016/j.scitotenv.2014.06.051 [17] BEIRAS R, VERDEJO E, CAMPOY-LÓPEZ P, et al. Aquatic toxicity of chemically defined microplastics can be explained by functional additives [J]. Journal of Hazardous Materials, 2021, 406: 124338. doi: 10.1016/j.jhazmat.2020.124338 [18] ANDRADY A L. The plastic in microplastics: A review [J]. Marine Pollution Bulletin, 2017, 119(1): 12-22. doi: 10.1016/j.marpolbul.2017.01.082 [19] GEWERT B, PLASSMANN M M, MACLEOD M. Pathways for degradation of plastic polymers floating in the marine environment [J]. Environmental Science. Processes & Impacts, 2015, 17(9): 1513-1521. [20] LIU P, SHI Y Q, WU X W, et al. Review of the artificially-accelerated aging technology and ecological risk of microplastics [J]. Science of the Total Environment, 2021, 768: 144969. doi: 10.1016/j.scitotenv.2021.144969 [21] TURNER A, HOLMES L. Occurrence, distribution and characteristics of beached plastic production pellets on the island of Malta (central Mediterranean) [J]. Marine Pollution Bulletin, 2011, 62(2): 377-381. doi: 10.1016/j.marpolbul.2010.09.027 [22] EDGE M, LIAUW C M, ALLEN N S, et al. Surface pinking in titanium dioxide/lead stabiliser filled PVC profiles [J]. Polymer Degradation and Stability, 2010, 95(10): 2022-2040. doi: 10.1016/j.polymdegradstab.2010.07.006 [23] CAI L Q, WANG J D, PENG J P, et al. Observation of the degradation of three types of plastic pellets exposed to UV irradiation in three different environments [J]. Science of the Total Environment, 2018, 628/629: 740-747. doi: 10.1016/j.scitotenv.2018.02.079 [24] ZHANG H B, WANG J Q, ZHOU B Y, et al. Enhanced adsorption of oxytetracycline to weathered microplastic polystyrene: Kinetics, isotherms and influencing factors [J]. Environmental Pollution, 2018, 243: 1550-1557. doi: 10.1016/j.envpol.2018.09.122 [25] DONG M T, ZHANG Q Q, XING X L, et al. Raman spectra and surface changes of microplastics weathered under natural environments [J]. Science of the Total Environment, 2020, 739: 139990. doi: 10.1016/j.scitotenv.2020.139990 [26] HO W K, LAW J C F, ZHANG T, et al. Effects of weathering on the sorption behavior and toxicity of polystyrene microplastics in multi-solute systems [J]. Water Research, 2020, 187: 116419. doi: 10.1016/j.watres.2020.116419 [27] TANG C C, CHEN H I, BRIMBLECOMBE P, et al. Morphology and chemical properties of polypropylene pellets degraded in simulated terrestrial and marine environments [J]. Marine Pollution Bulletin, 2019, 149: 110626. doi: 10.1016/j.marpolbul.2019.110626 [28] TANG C C, CHEN H I, BRIMBLECOMBE P, et al. Textural, surface and chemical properties of polyvinyl chloride particles degraded in a simulated environment [J]. Marine Pollution Bulletin, 2018, 133: 392-401. doi: 10.1016/j.marpolbul.2018.05.062 [29] TER HALLE A, LADIRAT L, GENDRE X, et al. Understanding the fragmentation pattern of marine plastic debris [J]. Environmental Science & Technology, 2016, 50(11): 5668-5675. [30] JULIENNE F, LAGARDE F, DELORME N. Influence of the crystalline structure on the fragmentation of weathered polyolefines [J]. Polymer Degradation and Stability, 2019, 170: 109012. doi: 10.1016/j.polymdegradstab.2019.109012 [31] HEBNER T S, MAURER-JONES M A. Characterizing microplastic size and morphology of photodegraded polymers placed in simulated moving water conditions [J]. Environmental Science. Processes & Impacts, 2020, 22(2): 398-407. [32] JULIENNE F, DELORME N, LAGARDE F. From macroplastics to microplastics: Role of water in the fragmentation of polyethylene [J]. Chemosphere, 2019, 236: 124409. doi: 10.1016/j.chemosphere.2019.124409 [33] LI Z W, HU X L, QIN L X, et al. Evaluating the effect of different modified microplastics on the availability of polycyclic aromatic hydrocarbons [J]. Water Research, 2020, 170: 115290. doi: 10.1016/j.watres.2019.115290 [34] HÜFFER T, WENIGER A K, HOFMANN T. Sorption of organic compounds by aged polystyrene microplastic particles [J]. Environmental Pollution, 2018, 236: 218-225. doi: 10.1016/j.envpol.2018.01.022 [35] LUO H W, ZHAO Y Y, LI Y, et al. Aging of microplastics affects their surface properties, thermal decomposition, additives leaching and interactions in simulated fluids [J]. Science of the Total Environment, 2020, 714: 136862. doi: 10.1016/j.scitotenv.2020.136862 [36] HUANG Y J, DING J N, ZHANG G S, et al. Interactive effects of microplastics and selected pharmaceuticals on red tilapia: Role of microplastic aging [J]. Science of the Total Environment, 2021, 752: 142256. doi: 10.1016/j.scitotenv.2020.142256 [37] SORASAN C, EDO C, GONZÁLEZ-PLEITER M, et al. Generation of nanoplastics during the photoageing of low-density polyethylene [J]. Environmental Pollution, 2021, 289: 117919. doi: 10.1016/j.envpol.2021.117919 [38] LAMBERT S, WAGNER M. Formation of microscopic particles during the degradation of different polymers [J]. Chemosphere, 2016, 161: 510-517. doi: 10.1016/j.chemosphere.2016.07.042 [39] SONG Y K, HONG S H, EO S, et al. Rapid production of micro- and nanoplastics by fragmentation of expanded polystyrene exposed to sunlight [J]. Environmental Science & Technology, 2020, 54(18): 11191-11200. [40] VETRIMURUGAN E, JONATHAN M P, SARKAR S K, et al. Occurrence, distribution and provenance of micro plastics: A large scale quantitative analysis of beach sediments from southeastern coast of South Africa [J]. Science of the Total Environment, 2020, 746: 141103. doi: 10.1016/j.scitotenv.2020.141103 [41] SATHISH N, JEYASANTA K I, PATTERSON J. Abundance, characteristics and surface degradation features of microplastics in beach sediments of five coastal areas in Tamil Nadu, India [J]. Marine Pollution Bulletin, 2019, 142: 112-118. doi: 10.1016/j.marpolbul.2019.03.037 [42] BRANDON J, GOLDSTEIN M, OHMAN M D. Long-term aging and degradation of microplastic particles: Comparing in situ oceanic and experimental weathering patterns [J]. Marine Pollution Bulletin, 2016, 110(1): 299-308. doi: 10.1016/j.marpolbul.2016.06.048 [43] LIU P, QIAN L, WANG H Y, et al. New insights into the aging behavior of microplastics accelerated by advanced oxidation processes [J]. Environmental Science & Technology, 2019, 53(7): 3579-3588. [44] ENDO S, TAKIZAWA R, OKUDA K, et al. Concentration of polychlorinated biphenyls (PCBs) in beached resin pellets: Variability among individual particles and regional differences [J]. Marine Pollution Bulletin, 2005, 50(10): 1103-1114. doi: 10.1016/j.marpolbul.2005.04.030 [45] LIU P, LU K, LI J L, et al. Effect of aging on adsorption behavior of polystyrene microplastics for pharmaceuticals: Adsorption mechanism and role of aging intermediates [J]. Journal of Hazardous Materials, 2020, 384: 121193. doi: 10.1016/j.jhazmat.2019.121193 [46] LIU X M, SUN P P, QU G J, et al. Insight into the characteristics and sorption behaviors of aged polystyrene microplastics through three type of accelerated oxidation processes [J]. Journal of Hazardous Materials, 2021, 407: 124836. doi: 10.1016/j.jhazmat.2020.124836 [47] WU J, XU P C, CHEN Q H, et al. Effects of polymer aging on sorption of 2, 2', 4, 4'-tetrabromodiphenyl ether by polystyrene microplastics [J]. Chemosphere, 2020, 253: 126706. doi: 10.1016/j.chemosphere.2020.126706 [48] ZHANG J H, CHEN H B, HE H, et al. Adsorption behavior and mechanism of 9-Nitroanthracene on typical microplastics in aqueous solutions [J]. Chemosphere, 2020, 245: 125628. doi: 10.1016/j.chemosphere.2019.125628 [49] WANG Q J, ZHANG Y, WANGJIN X X, et al. The adsorption behavior of metals in aqueous solution by microplastics effected by UV radiation [J]. Journal of Environmental Sciences, 2020, 87: 272-280. doi: 10.1016/j.jes.2019.07.006 [50] FU Q M, TAN X F, YE S J, et al. Mechanism analysis of heavy metal lead captured by natural-aged microplastics [J]. Chemosphere, 2021, 270: 128624. doi: 10.1016/j.chemosphere.2020.128624 [51] FAN X L, MA Z X, ZOU Y F, et al. Investigation on the adsorption and desorption behaviors of heavy metals by tire wear particles with or without UV ageing processes [J]. Environmental Research, 2021, 195: 110858. doi: 10.1016/j.envres.2021.110858 [52] LIU G Z, ZHU Z L, YANG Y X, et al. Sorption behavior and mechanism of hydrophilic organic chemicals to virgin and aged microplastics in freshwater and seawater [J]. Environmental Pollution, 2019, 246: 26-33. doi: 10.1016/j.envpol.2018.11.100 [53] FAN X L, GAN R, LIU J Q, et al. Adsorption and desorption behaviors of antibiotics by tire wear particles and polyethylene microplastics with or without aging processes [J]. Science of the Total Environment, 2021, 771: 145451. doi: 10.1016/j.scitotenv.2021.145451 [54] LAN T, WANG T, CAO F, et al. A comparative study on the adsorption behavior of pesticides by pristine and aged microplastics from agricultural polyethylene soil films [J]. Ecotoxicology and Environmental Safety, 2021, 209: 111781. doi: 10.1016/j.ecoenv.2020.111781 [55] MAO Y F, LI H, HUANGFU X L, et al. Nanoplastics display strong stability in aqueous environments: Insights from aggregation behaviour and theoretical calculations [J]. Environmental Pollution, 2020, 258: 113760. doi: 10.1016/j.envpol.2019.113760 [56] LIU Y J, HU Y B, YANG C, et al. Aggregation kinetics of UV irradiated nanoplastics in aquatic environments [J]. Water Research, 2019, 163: 114870. doi: 10.1016/j.watres.2019.114870 [57] 何曼君, 张红东, 陈维孝, 等. 高分子物理 [M]. 第三版, 上海: 复旦大学出版社, 2008: 103-148. HE M J, ZHANG H D, CHEN W X, et al. Polymer physics [M]. 3rd Edition, Shanghai: Fudan University Press, 2008: 103-148.
[58] MÜLLER A, BECKER R, DORGERLOH U, et al. The effect of polymer aging on the uptake of fuel aromatics and ethers by microplastics [J]. Environmental Pollution, 2018, 240: 639-646. doi: 10.1016/j.envpol.2018.04.127 [59] RABELLO M S, WHITE J R. Crystallization and melting behaviour of photodegraded polypropylene—II. Re-crystallization of degraded molecules [J]. Polymer, 1997, 38(26): 6389-6399. doi: 10.1016/S0032-3861(97)00214-0 [60] LV Y, HUANG Y J, YANG J L, et al. Outdoor and accelerated laboratory weathering of polypropylene: A comparison and correlation study [J]. Polymer Degradation and Stability, 2015, 112: 145-159. doi: 10.1016/j.polymdegradstab.2014.12.023 [61] ANDRADY A L. Microplastics in the marine environment [J]. Marine Pollution Bulletin, 2011, 62(8): 1596-1605. doi: 10.1016/j.marpolbul.2011.05.030 [62] GARVEY C J, IMPÉROR-CLERC M, ROUZIÈRE S, et al. Molecular-scale understanding of the embrittlement in polyethylene ocean debris [J]. Environmental Science & Technology, 2020, 54(18): 11173-11181. [63] CECCARINI A, CORTI A, ERBA F, et al. The hidden microplastics: New insights and figures from the thorough separation and characterization of microplastics and of their degradation byproducts in coastal sediments [J]. Environmental Science & Technology, 2018, 52(10): 5634-5643. [64] MAO R F, LANG M F, YU X Q, et al. Aging mechanism of microplastics with UV irradiation and its effects on the adsorption of heavy metals [J]. Journal of Hazardous Materials, 2020, 393: 122515. doi: 10.1016/j.jhazmat.2020.122515 [65] ZHU K C, JIA H Z, ZHAO S, et al. Formation of environmentally persistent free radicals on microplastics under light irradiation [J]. Environmental Science & Technology, 2019, 53(14): 8177-8186. [66] ZHU K C, JIA H Z, SUN Y J, 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. doi: 10.1016/j.watres.2020.115564 [67] BIANCO A, SORDELLO F, EHN M, et al. Degradation of nanoplastics in the environment: Reactivity and impact on atmospheric and surface waters [J]. Science of the Total Environment, 2020, 742: 140413. doi: 10.1016/j.scitotenv.2020.140413 [68] TIAN L L, CHEN Q Q, JIANG W, et al. A carbon-14 radiotracer-based study on the phototransformation of polystyrene nanoplastics in water versus in air [J]. Environmental Science:Nano, 2019, 6(9): 2907-2917. doi: 10.1039/C9EN00662A [69] SHARPLESS C M, BLOUGH N V. The importance of charge-transfer interactions in determining chromophoric dissolved organic matter (CDOM) optical and photochemical properties [J]. Environmental Science. Processes & Impacts, 2014, 16(4): 654-671. [70] WENK J, EUSTIS S N, MCNEILL K, et al. Quenching of excited triplet states by dissolved natural organic matter [J]. Environmental Science & Technology, 2013, 47(22): 12802-12810. [71] WU X W, LIU P, WANG H Y, et al. Photo aging of polypropylene microplastics in estuary water and coastal seawater: Important role of chlorine ion [J]. Water Research, 2021, 202: 117396. doi: 10.1016/j.watres.2021.117396 [72] DING L, OUYANG Z Z, LIU P, et al. Photodegradation of microplastics mediated by different types of soil: The effect of soil components [J]. Science of the Total Environment, 2022, 802: 149840. doi: 10.1016/j.scitotenv.2021.149840 [73] WANG C, XIAN Z Y, JIN X, et al. Photo-aging of polyvinyl chloride microplastic in the presence of natural organic acids [J]. Water Research, 2020, 183: 116082. doi: 10.1016/j.watres.2020.116082 [74] LIANG S J, XU S X, WANG C, et al. Enhanced alteration of poly(vinyl chloride) microplastics by hydrated electrons derived from indole-3-acetic acid assisted by a common cationic surfactant [J]. Water Research, 2021, 191: 116797. doi: 10.1016/j.watres.2020.116797 [75] CHENG H F, LUO H, HU Y, et al. Release kinetics as a key linkage between the occurrence of flame retardants in microplastics and their risk to the environment and ecosystem: A critical review [J]. Water Research, 2020, 185: 116253. doi: 10.1016/j.watres.2020.116253 [76] HAHLADAKIS J N, VELIS C A, WEBER R, et al. An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling [J]. Journal of Hazardous Materials, 2018, 344: 179-199. doi: 10.1016/j.jhazmat.2017.10.014 [77] HERMABESSIERE L, DEHAUT A, PAUL-PONT I, et al. Occurrence and effects of plastic additives on marine environments and organisms: A review [J]. Chemosphere, 2017, 182: 781-793. doi: 10.1016/j.chemosphere.2017.05.096 [78] XIAO L H, ZHENG Z Y, IRGUM K, et al. Studies of emission processes of polymer additives into water using quartz crystal microbalance—A case study on organophosphate esters [J]. Environmental Science & Technology, 2020, 54(8): 4876-4885. [79] SUN B B, HU Y, CHENG H F, et al. Releases of brominated flame retardants (BFRs) from microplastics in aqueous medium: Kinetics and molecular-size dependence of diffusion [J]. Water Research, 2019, 151: 215-225. doi: 10.1016/j.watres.2018.12.017 [80] RANI M, SHIM W J, JANG M, et al. Releasing of hexabromocyclododecanes from expanded polystyrenes in seawater -field and laboratory experiments [J]. Chemosphere, 2017, 185: 798-805. doi: 10.1016/j.chemosphere.2017.07.042 [81] LIU X M, SHI H H, XIE B, et al. Microplastics as both a sink and a source of bisphenol A in the marine environment [J]. Environmental Science & Technology, 2019, 53(17): 10188-10196. [82] KHALED A, RICHARD C, REDIN L, et al. Characterization and photodegradation of polybrominated diphenyl ethers in car seat fabrics from end-of-life vehicles [J]. Environmental Science & Technology, 2018, 52(3): 1216-1224. [83] KHALED A, RICHARD C, RIVATON A, et al. Photodegradation of brominated flame retardants in polystyrene: Quantum yields, products and influencing factors [J]. Chemosphere, 2018, 211: 943-951. doi: 10.1016/j.chemosphere.2018.07.147 [84] WANG H Y, LIU P, WANG M J, et al. Enhanced phototransformation of atorvastatin by polystyrene microplastics: Critical role of aging [J]. Journal of Hazardous Materials, 2021, 408: 124756. doi: 10.1016/j.jhazmat.2020.124756 [85] CHEN C Z, CHEN L, YAO Y, et al. Organotin release from polyvinyl chloride microplastics and concurrent photodegradation in water: Impacts from salinity, dissolved organic matter, and light exposure [J]. Environmental Science & Technology, 2019, 53(18): 10741-10752. [86] LUO H W, LI Y, ZHAO Y Y, et al. Effects of accelerated aging on characteristics, leaching, and toxicity of commercial lead chromate pigmented microplastics [J]. Environmental Pollution, 2020, 257: 113475. doi: 10.1016/j.envpol.2019.113475 [87] LUO H W, XIANG Y H, LI Y, et al. Weathering alters surface characteristic of TiO2-pigmented microplastics and particle size distribution of TiO2 released into water [J]. Science of the Total Environment, 2020, 729: 139083. doi: 10.1016/j.scitotenv.2020.139083 [88] LIU H T, LIU K, FU H Y, et al. Sunlight mediated cadmium release from colored microplastics containing cadmium pigment in aqueous phase [J]. Environmental Pollution, 2020, 263: 114484. doi: 10.1016/j.envpol.2020.114484 [89] PALUSELLI A, FAUVELLE V, GALGANI F, et al. Phthalate release from plastic fragments and degradation in seawater [J]. Environmental Science & Technology, 2019, 53(1): 166-175. [90] LUO H W, XIANG Y H, HE D Q, et al. Leaching behavior of fluorescent additives from microplastics and the toxicity of leachate to Chlorella vulgaris [J]. Science of the Total Environment, 2019, 678: 1-9. doi: 10.1016/j.scitotenv.2019.04.401 [91] LEE Y K, MURPHY K R, HUR J. Fluorescence signatures of dissolved organic matter leached from microplastics: Polymers and additives [J]. Environmental Science & Technology, 2020, 54(19): 11905-11914. [92] SHI Y Q, LIU P, WU X W, et al. Insight into chain scission and release profiles from photodegradation of polycarbonate microplastics [J]. Water Research, 2021, 195: 116980. doi: 10.1016/j.watres.2021.116980 [93] LEE Y K, ROMERA-CASTILLO C, HONG S, et al. Characteristics of microplastic polymer-derived dissolved organic matter and its potential as a disinfection byproduct precursor [J]. Water Research, 2020, 175: 115678. doi: 10.1016/j.watres.2020.115678 [94] LOMONACO T, MANCO E, CORTI A, et al. Release of harmful volatile organic compounds (VOCs) from photo-degraded plastic debris: A neglected source of environmental pollution [J]. Journal of Hazardous Materials, 2020, 394: 122596. doi: 10.1016/j.jhazmat.2020.122596 [95] la NASA J, LOMONACO T, MANCO E, et al. Plastic breeze: Volatile organic compounds (VOCs) emitted by degrading macro- and microplastics analyzed by selected ion flow-tube mass spectrometry [J]. Chemosphere, 2021, 270: 128612. doi: 10.1016/j.chemosphere.2020.128612 [96] KHALED A, RIVATON A, RICHARD C, et al. Phototransformation of plastic containing brominated flame retardants: Enhanced fragmentation and release of photoproducts to water and air [J]. Environmental Science & Technology, 2018, 52(19): 11123-11131. [97] WALSH A N, REDDY C M, NILES S F, et al. Plastic formulation is an emerging control of its photochemical fate in the ocean [J]. Environmental Science & Technology, 2021, 55(18): 12383-12392. [98] ROMERA-CASTILLO C, PINTO M, LANGER T M, et al. Dissolved organic carbon leaching from plastics stimulates microbial activity in the ocean [J]. Nature Communications, 2018, 9: 1430. doi: 10.1038/s41467-018-03798-5 [99] ZHU L X, ZHAO S Y, BITTAR T B, et al. Photochemical dissolution of buoyant microplastics to dissolved organic carbon: Rates and microbial impacts [J]. Journal of Hazardous Materials, 2020, 383: 121065. doi: 10.1016/j.jhazmat.2019.121065 [100] ATEIA M, KANAN A, KARANFIL T. Microplastics release precursors of chlorinated and brominated disinfection byproducts in water [J]. Chemosphere, 2020, 251: 126452. doi: 10.1016/j.chemosphere.2020.126452 [101] KWON B G, KOIZUMI K, CHUNG S Y, et al. Global styrene oligomers monitoring as new chemical contamination from polystyrene plastic marine pollution [J]. Journal of Hazardous Materials, 2015, 300: 359-367. doi: 10.1016/j.jhazmat.2015.07.039 [102] KWON B G, SAIDO K, KOIZUMI K, et al. Regional distribution of styrene analogues generated from polystyrene degradation along the coastlines of the North-East Pacific Ocean and Hawaii [J]. Environmental Pollution, 2014, 188: 45-49. doi: 10.1016/j.envpol.2014.01.019 [103] WARD C P, ARMSTRONG C J, WALSH A N, et al. Sunlight converts polystyrene to carbon dioxide and dissolved organic carbon [J]. Environmental Science & Technology Letters, 2019, 6(11): 669-674. [104] GEWERT B, PLASSMANN M, SANDBLOM O, et al. Identification of chain scission products released to water by plastic exposed to ultraviolet light [J]. Environmental Science & Technology Letters, 2018, 5(5): 272-276. [105] SØRENSEN L, GROVEN A S, HOVSBAKKEN I A, et al. UV degradation of natural and synthetic microfibers causes fragmentation and release of polymer degradation products and chemical additives [J]. Science of the Total Environment, 2021, 755: 143170. doi: 10.1016/j.scitotenv.2020.143170 [106] SAIT S T L, SØRENSEN L, KUBOWICZ S, et al. Microplastic fibres from synthetic textiles: Environmental degradation and additive chemical content [J]. Environmental Pollution, 2021, 268: 115745. doi: 10.1016/j.envpol.2020.115745 -
