2023, Vol. 44
2. 河北大学生态环境系, 保定 071000;
3. 河北农业大学国土资源学院, 保定 071000;
4. 河北省农田生态环境重点实验室, 保定 071000;
5. 河北省山区农业技术创新中心, 保定 071000;
6. 河北农业大学河北省山区研究所, 保定 071000
, LI Yu-xin2 , RONG Sa-shuang1 , WANG Wan-qing3,4 , WANG Xin-xin5,6 , GUO Jia-peng2 , HAN Bing1 , WANG Shu-tao3,4
2. School of Eco-Environment, Hebei University, Baoding 071000, China;
3. College of Land and Resources, Hebei Agricultural University, Baoding 071000, China;
4. Key Laboratory of Agro-Ecological Environment of Hebei Province, Baoding 071000, China;
5. Hebei Agricultural Technology Innovation Center, Baoding 071000, China;
6. Mountain Area Research Institute of Hebei Province, Hebei Agricultural University, Baoding 071000, China
1909年出现了第一种人工合成的塑料——酚醛塑料, 由于其优良的化学稳定性、耐腐蚀性及低廉的成本等优点, 塑料产量快速增长并被广泛应用于农业、工业、建筑和包装等众多领域.据统计, 全球塑料产量在1950~2020年间由150 t增长到3.67亿t[1], 其中2020年我国塑料产量达到1.05亿t以上[2], 预计到2050年塑料产量将增长3倍[3].塑料还具有种类繁多的特点, 主要包括聚酰胺(polyamide, PA)、聚对苯二甲酸乙二醇酯(polyethylene terephthalate, PET)、聚乙烯(polyethylene, PE)、聚丙烯(polypropylene, PP)、聚苯乙烯(polystyrene, PS)、聚醚砜(polyethersulfone, PES)和聚氯乙烯(polyvinyl chloride, PVC)等.然而, 据欧盟统计, 欧洲仅有约16%的塑料被回收利用[4].有研究发现, 大约32%的塑料废物存在于土壤环境中[5], 在物理、化学和生物因素的协同作用下[6], 降解为大小 < 5 mm的塑料颗粒——微塑料(microplastics, MPs)[7].MPs进一步经物理、化学和生物过程降解为尺寸 < 0.1 μm的塑料颗粒——纳米塑料(nanoplastics, NPs)[8].微/纳米塑料在环境中多种物理、化学因素作用下可发生化学键断裂, 产生环境持久性自由基以及活性氧等易被生物体吸收的物质, 使生物体产生氧化应激反应, 最终导致机体损伤[9].
土壤是MPs主要的储存地.有研究发现, 上海菜地MPs丰度为62.50~275.00个·kg-1, 主要类型为0.03~16 mm的PE(50%)和PP(43%)[10]; 印度沿河土壤中MPs丰度为26.61~205.06个·kg-1, 主要类型为0.3~5 mm的PE(84%)、PET(7%)和PP(5.00%)[11]; 湛江红树林中MPs丰度为108.00~486.00个·kg-1, 主要类型为2.94 μm~4.40 mm的PE(61%)、PP(18%)和PS(7%)[12].而土壤作为植物根系生长的基质, MPs的土壤积累直接影响植物生长.Bosker等[13]研究表明, 积累在土壤中的MPs可黏附在根表, 对植物根系产生机械损伤; 微米级和亚微米级MPs甚至可被植物根系吸收[14], 降低植物的存活率和生物量[15].MPs除了对植物产生直接毒性外, 还可以通过影响土壤容重、团聚体组成、持水性和pH等理化性质, 以及作为污染物(如有机物、重金属)的载体携带污染物, 间接抑制植物生长发育.此外, MPs在降解过程中产生的有机磷酸酯、芳香化合物、酮和醇等[16]有机污染物亦可造成细胞损伤, 包括降低植物的光合作用[17]、对细胞器造成损伤、使植物叶子发黄和扎根无力等[18], 因此本文分析土壤中MPs的降解机制可以明确降解中间产物, 以期为调控MPs污染和减小生物毒性提供参考.
1 微塑料对陆生植物的毒性效应MPs由于其较大的比表面积, 对重金属和疏水性有机污染物等特征污染物具有较强的吸附性, 可作为污染物载体促进其在土壤中的存留.同时, 塑料生产过程中的增塑剂和着色剂等多种添加剂可在降解过程中释放并在环境中长期存在.除此之外, 越来越多的研究证明MPs可被根系吸收并运输到植物地上部分, 抑制植物生长, 如图 1所示.但目前关于MPs对于植物毒性作用的研究, 还停留在对植物生长和性状、植物体内分布的影响阶段, 关于MPs在植物体内运输、分布及影响机制尚不明确.因此, 解读MPs在土壤中的生态过程, 评价MPs对植物的毒理学效应对保障植物生产和维护食物链安全等方面尤为重要.
|
图 1 微塑料对植物的毒性效应 Fig. 1 Toxic effects of microplastics on plants |
土壤中的MPs会直接影响植物的生长, 如延缓种子发芽、降低发芽率及幼苗成活率[19]、显著改变植物生物量、根系性状, 甚至被植物吸收蓄积产生生物放大、生物转化效应, 从而对植物产生遗传毒性[20].李连祯等[21]将生菜(Lactuca sativa)经含有粒径为0.2 μm、ρ(PS)为50 mg·L-1的营养液单独处理后, 发现根表面有少量形似葡萄串状的MPs颗粒, 对根造成机械损伤, 抑制根系活力和生菜生长.土壤中MPs还会影响植物根系对水分及养分的有效吸收[22, 23], 有研究发现PA能使洋葱鳞茎的含水量与叶片的含氮量均增加50%, 而PES使洋葱(Allium cepa)鳞茎的含水量与叶片的含氮量小幅降低[24], 造成这种影响差异的原因可能是MPs种类不同.MPs在植物体内的分布与其粒径密切相关, MPs粒径越小越容易进入植物根系并被转运到植物的各个组织中[25], 并产生细胞毒性.据荧光标记扫描电镜观察, 0.2 μm的PS可传输至小麦茎叶中, 并未在相同位置观察到2 μm的PS[26].Bandmann等[27]进一步发现, NPs可通过细胞内吞作用进入烟草细胞, 改变细胞膜结构和膜蛋白活性, 进一步改变细胞功能[28], 甚至导致细胞死亡[29]; Giorgetti等[30]也发现纳米塑料可以进入洋葱根分生区细胞, 引起氧化胁迫并产生细胞毒性(如有丝分裂异常)和基因毒性.
环境中MPs因摩擦、光照和温差等影响不断老化, 造成粒径、电性和稳定性不同, 对植物的毒性效应呈现多变的特点.老化MPs的表面粗糙程度增加, 对植物根系的机械损伤增强[31].有研究指出, 土壤中纳米塑料所带电荷不同时, 对拟南芥的生长抑制程度不同.细胞膜与细胞壁本身带负电, 因此带正电的MPs更容易被吸附在植物根部, 对拟南芥(Arabidopsis thaliana)的抑制作用更强, 与对照(即未添加MPs的盆栽土培试验)相比鲜重下降50%以上.带负电的MPs更倾向于被植物吸收分布于木质部和中柱附近[32].MPs的粒径也是影响植物体内MPs毒性的重要因素, 微米级PE在ρ(PE)为10、50和100 mg·L-1时均显著抑制蚕豆(Vicia faba)生长, 但纳米PE仅在ρ(PE)为100 mg·L-1时抑制蚕豆生长, 且纳米级塑料颗粒对蚕豆的生态毒性和遗传毒性较微米级要大[33].
1.2 微塑料对植物的间接毒性MPs可以通过改变土壤理化性质、释放内源污染物及吸附重金属和有机污染物等方式间接影响植物生长和代谢.MPs进入土壤后, 由于其密度通常比土壤小, 会改变土壤容重[34]; 同时, MPs与土壤结合后会改变土壤中水分的蒸发速度, 增加水稳性团聚体数量和大孔隙体积, 从而破坏土壤团聚结构[35, 36].而土壤孔隙度和土壤水含量改变氧气的分布, 从而改变好氧微生物和厌氧微生物的相对分布[37], 影响根系活性.综上, MPs积累引起的土壤理化性质改变会对植物的养分吸收、呼吸作用和生长发育造成不良影响.有研究发现MPs纤维在土壤中保持水分的时间更长[38], 薄膜降低了土壤的容重, 泡沫和碎片可以增加土壤的通气性和大孔隙度, 因此纤维、薄膜、泡沫和碎片等不同形状的MPs分别使植物地上部分生物量增加27%、60%、45%和54%.但有另外的研究发现平均直径2 mm的PE碎片(质量分数0.5%)显著增加了土壤水分的蒸发速率, 导致土壤贫瘠化[39], 使得植物生长状况不佳.植物根系周围通常较易聚集MPs, 这些MPs会通过改变植物根际微生物群落组成及活性, 影响植物根际的土壤肥力[40].有研究发现添加PE微塑料对豆科植物中根瘤共生有一定的促进作用[41], 而聚酯纤维的添加显著增加了洋葱(Allium cepa)根部的丛枝菌根菌丝定殖量[42], 这表明MPs可能影响根瘤菌活性和固氮能力.因此MPs影响下会对微生物群落产生作用, 进而影响土壤-植物系统稳定性.
此外, 塑料加工过程中添加的邻苯二甲酸酯、双酚A、壬基酚、溴化阻燃剂和有机磷酸酯类阻燃剂等添加剂会随塑料进入土壤并通过磨损、挥发和浸出等方式被释放到土壤中.MPs的羰基指数、比表面积等会在其老化过程中增加[43], 而塑料物理化学性质的改变会促进添加剂的浸出行为[44].例如, 有研究发现MPs在光老化降解的过程中铬酸铅颜料及邻苯二甲酸酯的释放量均会增加2~3倍[45, 46].这些添加剂释放到环境中后, 会抑制有益微生物, 减弱土壤生物功能, 甚至通过植物根部吸收, 在植物体中富集并经食物链进入人体, 造成健康风险[47].如邻苯二甲酸二(2-乙基己基)酯的加入会显著降低微生物的数量, 与空白组相比降低率为35.77%[48].李海峰等[49]研究发现不同浓度的邻苯二甲酸酯可以使葡萄的枝条长度、地上部分生物量、叶绿素、总糖及总蛋白质含量降低.
1.3 微塑料与多种污染物对植物的联合毒性MPs对环境污染物的吸附和富集也是MPs具有生态毒性的重要原因[50, 51].MPs由于其比表面积大, 具有载体效应, 易与土壤中重金属及有机污染物对植物产生联合毒性, 通过增加摄入浓度、加剧组织损伤等方式增强MPs的毒性[52].
首先, MPs对不同重金属具有吸附作用[53], 增强重金属生物有效性, 呈现复合毒性.孙聪惠[54]研究显示渤海湾沉积物中MPs吸附的Hg和Cd含量均高于背景值, 而Hg、Cd和Pb等多种重金属可随MPs进入机体, 在生物体内累积, 引起毒性效应.Abbasi等[55]研究发现PET颗粒可以作为载体将Cd、Pb和Zn这3种重金属迁移至小麦根际, 并在此进行解吸, 促进重金属向植物体中转移.有研究表明, 聚酯MPs和不同剂量Cd的联合暴露使生菜植株的分枝长度减少20%~30%, 叶绿素含量降低约十分之一, 降低光合速率[56].水稻生物量随MPs与As联合浓度增加而降低, 最大降幅可达26.2%[57].由于重金属与MPs之间的作用与吸附相比更容易解吸, 因此土壤中添加MPs通常会增强重金属的生物有效性[58], 继而对植物的毒性作用增强.值得注意的是, 老化会影响MPs与重金属的联合毒性, 在5 mg·L-1水培浓度和100 mg·kg-1土培含量下, 原始PVC微塑料不影响Cd对小麦的毒性效应, 老化后的PVC微塑料与低浓度Cd会对小麦根生长起到协同抑制作用, 这可能是因为老化MPs可以提高Cd在小麦体内的生物富集量[59].虽然MPs与重金属复合污染会对植物生长产生抑制, 但也有研究发现MPs的存在可以使植物受到重金属的危害程度降低.Lian等[60]研究了PS与重金属Cd复合污染对小麦(Triticum aestivum L.)的影响, 发现PS微塑料的存在可以降低叶片中Cd的含量, 同时碳水化合物和氨基酸代谢均增加, 缓解Cd对小麦的氧化损伤.这是由于MPs通过物理吸附和共沉降, 减少重金属的交换态、碳酸盐结合态和铁锰氧化物结合态, 增加有机结合态, 降低重金属在土壤中的生物有效性和迁移性[61], 从而降低重金属对作物的毒性.
其次, 由于MPs的强疏水性及其与农田土壤中抗生素等有机污染物相似的辛醇/水分配系数(Kow), MPs易吸附有机污染物[62], 增加土壤中有机污染物的残留量, 造成植物损伤.如MPs的存在使农药在土壤中的残留比例从4%提高到了15%[63].已有研究证明MPs可作为多环芳烃(polycyclic aromatic hydrocarbons, PAHs)、多氯联苯(polychlorinated biphenyis, PCBs)、六氯环己烷(hexachlorocyclohexanes, HCHs)和滴滴涕(dichloro diphenyl trichloroethanes, DDTs)等有机污染物的载体[64~66].这些有机污染物残留在MPs的孔隙中会延长其持久性并增加污染物在土壤中的残留量[67~69].当前的研究结果初步呈现了MPs和有机污染物对植物的协同毒性, 具体机制还有待进一步探索[70].王胜利等[71]研究了PS颗粒和邻苯二甲酸二丁酯共存对生菜生物量和生化指标的影响, 发现二者共存加剧了对生菜的毒害作用, PS微塑料颗粒的加入增强了邻苯二甲酸二丁酯对生菜生物量的抑制.单宁等[72]利用PS微塑料与环丙沙星复合处理黑麦草(Lolium perenne L.), 发现与环丙沙星单一处理相比, 使黑麦草的生物量降低了约15%~89%.
综上所述, MPs会在复杂的土壤体系中与土壤颗粒、生物和污染物等多种污染发生作用并对有机、无机污染物的生物毒性产生影响, 但这种作用不是单一的对原有污染物毒性的增强或减弱, 而是与MPs的形态、粒径、降解特征和植物类型、土壤性质等密切相关, 错综复杂.因此, 虽然MPs与重金属和有机污染物之间的作用研究已在多角度开展, 但MPs的土壤降解行为及其与其他污染物的联合机制尚需要更广泛深入的研究, 以明确MPs在土壤环境中的生命周期及潜在效应.
2 土壤环境中微塑料的降解机制自然土壤中, 塑料会在机械降解[73]、化学降解和微生物降解的共同作用下发生分解和转化作用[74, 75], 降解产物也会对植物产生毒性, 因此分析土壤MPs的降解机制、确定其降解过程中的中间产物, 对进一步了解MPs的植物毒性有关键作用.土壤中MPs链式反应分解主要发生在化学降解中, 其降解速度常因塑料材质(如结构、结晶度和疏水性)和环境因素(如紫外线辐射强度、温度和湿度)不同而存在较大差异[76], 其中紫外线辐射是MPs发生降解的主要推动力.与此同时, 塑料性能也因其不断分解而降低, 外观上可能呈现塑料变色、变脆和容易断裂等现象, 促进大颗粒塑料向MPs和纳米塑料转化.在MPs分子大小达到可以被微生物吸收后, 微生物通过代谢将MPs完全矿化.综合多项研究发现, 土壤中MPs的降解机制以机械破碎、化学降解和生物降解为主, 多种降解因素互相影响, 共同促进环境因子对降解的作用过程[77~80].
2.1 土壤微塑料的机械降解和化学降解机械降解指由于机械能输入引发MPs的链化学反应.自然环境中, 多种外界作用可以引起聚合物的机械降解, 如高速剪切力、拉伸流动、直接的力学承载、摩擦和超声作用等.土壤中的MPs存在跳跃和拖动等物理过程, 土壤质地的粗糙程度以及气候因素中的风速、降水和温度等会影响MPs颗粒的机械能输入, 从而影响颗粒与颗粒之间的碰撞和降解.机械降解使MPs产生裂缝和凹坑, 为其他物质的滞留及氧化过程的发生提供了潜在场所[81], 有利于后续化学降解反应的进行.
MPs的化学降解是在光、热或其他化学物质的影响下进行氧化反应, 使分子链断裂而实现降解的过程, 主要包括光氧化降解和热氧化降解.在太阳光(波长290~400 nm)照射下, 塑料中的光敏剂或光敏感基团激发出电子活性, 促进分子链在一定温度、湿度以及氧气的环境下发生光氧化反应, 转化为可溶性小分子物质, 实现塑料降解.其中, 自然光中紫外线易被含有醛基、酮基和羰基的MPs所吸收, 引发光化学反应; 红外线被MPs吸收提高塑料温度, 加快热降解速度.Liu等[82]对紫外光老化过程中MPs粒径及数量的动态变化进行了研究, 发现在老化过程进行至24 h后, MPs的粒径中位数由4.8 μm降至1.3 μm, 颗粒数量增加了2倍.存在于土壤介质中的MPs由于受光照条件的限制, 光降解存在较大局限性.而且, 由于土壤中氧气的分布受耕作措施、气候变化等多种因素影响, 只有存在于日照时间长、光照充足条件下土壤表面的MPs易发生光氧化和热氧化降解.
MPs氧化降解的一般机制见表 1[83~85], 不同类型MPs光氧化和热氧化降解过程及机制比较相似, 即通过自由基反应进行, 分为4个阶段：①链引发阶段, 在光或热的条件下聚合物脱氢产生大分子. ②增殖阶段, 该阶段发生一系列连锁反应, 包括大分子自由基与氧的结合产生聚合物过氧自由基, 反应后与另一个聚合物分子中的氢结合, 生成氢过氧化物分子和新的大分子. ③链支化阶段, 增殖阶段形成的氢过氧化物分解成新的自由基, 新的自由基与聚合物分子中的氢结合生成更多的大分子化合物, 提高氧化速率. ④链终止阶段, 当自由基结合在一起或无法发生比例反应时, 最终反应终止形成非活性产物.
|
表 1 微塑料氧化降解的一般机制1) Table 1 General mechanism of oxidative degradation of microplastics |
土壤中MPs的化学降解过程复杂, 关键降解步骤易受到气候、土地利用方式等实际环境因素的影响.不同质地土壤中, 黏土、铁氧化物和二氧化锰等组分的含量与MPs的降解程度呈现正相关关系[86].太阳辐射、温度越高, MPs光降解、热降解速率越快, 且温度每增加10℃, 热降解速率增加1倍[87], 各地区的气候差异使MPs发生降解的环境温度及受到阳光照射的程度不同, 光、热氧化降解作用的效率也不同.耕作是农业生态系统常规管理方式, 也是促进土壤MPs形成的重要过程, 但耕作方式的差异会影响MPs进入土壤的深度和化学降解速度.例如, 传统耕作方式通常影响表层20~30 cm的土层, 而在免耕土壤中, 只影响最上层几厘米的土层[88].此外, 塑料加工过程中填充剂、着色剂、稳定剂和软化剂等添加剂为降解提供了有利起始位置.
2.2 土壤微塑料的微生物降解在机械和化学降解作用发生的同时, 微生物也会在塑料表面定殖改变塑料的物理化学特征[89, 90].当塑料暴露于环境一定时间后, 会变脆并碎裂至微生物可摄入的大小, 从而发生微生物降解作用.因此, 光/热氧化降解使塑料尺寸减小产生MPs及其他中间产物, 没有实现完全降解, 这些MPs在土壤微生物分泌的酶作用下进一步彻底分解. 如图 2所示, MPs的微生物降解作用一般分为两个阶段：首先, 微生物分泌的胞外酶与材料结合, 通过切断表面的高分子链, 生成小分子量化合物(低聚物、单体或挥发性有机物如短链羧酸、芳香化合物、酮、醛、醇和酯等[91~93]).进一步, MPs的降解产物通过透膜脂质被微生物摄入体内, 经过胞内酶参加的代谢作用矿化为甲烷等产物, 合成微生物活动所需的能量, 最终转化为水和二氧化碳[94].应用基因组学和蛋白质组学方法, 可以鉴定参与MPs降解的相关酶[95], 发现水解酶(如脂肪酶、酯酶和蛋白酶等)和氧化还原酶(如漆酶和过氧化物酶等)是两类降解塑料的主要胞外酶[96, 97].Zhang等[98]对经Aspergillus flavus PEDX3降解的PE颗粒样品与原始样品比较发现, 降解后样品的相对分子质量(26 064)与原始样品(55 135)相比下降了29 069.有研究表明MPs的生物可利用性主要受到分子量、表面官能团及亲疏水性的影响, 带氧化基团和亲水性的MPs更易被微生物降解[99].根据聚合物链上是否含有可被水解的化学键可将塑料分为可水解型和不可水解型.可水解塑料包含PA和PET等, 不可水解的塑料包括PE、PP、PS和PVC.其中, 不可水解塑料的C—C键骨架具有抗水解和酶降解特点[100].
|
图 2 微塑料的微生物降解过程 Fig. 2 Microbial degradation process of microplastics |
可水解塑料的微生物降解在水解酶的参与下完成.PET和PA含有酰胺或酯键等易降解的结构, 可以像木质素、纤维素等天然底物一样通过水解酶进行切割[101], 最终被微生物同化利用.PET的完全矿化主要涉及两条代谢途径, 即三羧酸循环和β-酮己二酸代谢(图 3).此外, Danso等[102]通过基因组技术鉴定塑料降解的参与基因, 发现与PET降解酶相关的基因有cut-2.KW3、Tcur_1278和lipIAF5-2等.目前对PA的降解微生物、酶及参与基因相关研究还比较匮乏[103], 因此未来应对PA的有效降解微生物、酶及降解基因进行研究, 并明确其代谢途径和中间产物, 确定PA的降解机制.
|
图 3 PET的微生物降解过程[104] Fig. 3 Microbial degradation process of PET |
对于不可水解塑料降解机制的研究还处在起步阶段, 可以降解不可水解塑料的酶主要是氧化还原酶, 部分研究报道了不可降解塑料的有效降解微生物, 但降解的中间产物和微生物利用途径仍是未知.对于PE的微生物降解过程来说, 发挥作用的微生物主要是真菌和细菌, 真菌分泌的锰过氧化物酶可以降低PE的抗拉强度和总分子量, 促进下一步降解过程[105], 细菌中变形菌门、厚壁菌门和放线菌门与PE的降解密切相关[106].细菌分泌的PE有效降解包括漆酶和烷烃水解酶[107, 108], 漆酶通过氧化裂解PE非晶态区域解聚聚合物, 从而在聚合物链中提供羰基区域[109]促进后续反应进行.烷烃水解酶是催化PE降解反应的关键酶, 有研究在Paenibacillus sp.菌株中检测到控制烷烃水解酶合成的alkB基因[110].尽管目前的研究发现锰过氧化物酶、漆酶和烷烃水解酶参与PE降解, 但微生物内部PE的代谢途径尚不清楚.有研究已经发现参与降解PP、PS和PVC的微生物[111, 112], 但是关于它们降解酶和降解机制的相关报道仍然较少.Urbanek等[113]对黄粉虫及其幼虫肠道微生物区系进行高通量NEXT基因测序分析鉴定, 发现克雷伯氏菌、假单胞菌、沙雷氏菌和木霉菌能够利用不同类型的塑料作为唯一碳源.真菌中的金孢子菌属和细菌中的香矛醇假单胞菌可以在30d内使PVC降解10%~20%[114].因此, 从微生物中寻找能够从环境中降解PE、PP、PS和PVC的胞内酶及代谢途径是未来可以深入研究的领域.
MPs进入土壤后的微生物降解过程与土壤微生物群组成、微生物降解能力等潜在因素有关.与单一微生物相比, 由多种微生物组成复合微生物群的降解作用可以通过共代谢提高降解效率.Skariyachan等[115]从牛粪中分离出IS1、IS2、IS3和IS4这4种菌株, 分别将单一菌株和按比例混合的复合菌株与PE一起培养120 d发现, 复合菌株降解的PE是单一菌株降解的4倍.一般认为真菌降解MPs的能力高于细菌, 且以丝状真菌最佳.主要原因是真菌具有独特的疏水蛋白, 该疏水蛋白的双层结构能在疏水/亲水界面形成两亲性膜作为生物表面活性剂提高底物的接触面积, 从而提高降解效率[116].综合多项研究表明, 当前关于MPs的微生物降解主要集中在聚乙烯塑料上, 对其他MPs降解菌探索较少, 见表 2.
|
|
表 2 具有降解微塑料能力的微生物 Table 2 Microorganisms with the ability to degrade microplastics |
目前关于MPs的降解研究大多停留在其质量变化、拉伸强度的改变及功能微生物的筛选等方面, 对微生物降解塑料机制的研究还很欠缺.只有为数不多的研究对MPs微生物降解过程中的酶进行了探索, 且目前研究重点也集中在胞外酶.在常用的塑料类型中, PVC、PP和PS微生物降解过程中的代谢途径仍不明确, 聚醚型和聚氨酯的降解机制研究更为缺乏, 这都是制约微生物降解MPs发展的关键问题.同时, 微生物对环境条件反应敏感, 而现有的降解研究仅在实验室理想条件进行, 因此探索实际土壤中MPs的微生物降解过程及降解微生物的适生性, 对有效评估MPs的实际环境中多种降解机制至关重要.
3 展望土壤MPs污染是一个全球性热点问题, MPs种类、形态和性质各异, 而土壤体系复杂多变, MPs对植物的影响及降解机制仍有一系列问题待深入探究.未来需重点关注以下4个方面.
(1) 目前土壤中MPs研究大多是在理想实验室条件下开展, 但实际土壤条件复杂多变, 有机、无机污染物种类和含量各不相同, 因此分析土壤中MPs毒性及降解机制还应充分考虑多种因素之间交叉影响.
(2) 当前研究初步探索MPs在土壤及植物的分布、迁移及其毒性效应, MPs与其他污染物复合污染对植物生长的影响及其联合机制研究还不充分, 应结合化学、生物手段对其实际环境行为、植物对MPs毒性反应机制进行深入研究.
(3) 已有研究探明植物的MPs积累效应, 但MPs是否会沿食物链进入人体并产生健康风险尚未明确, 因此亟需建立标准的MPs健康风险评估方法, 为人类健康防护提供参考.
(4) 目前PVC、PP和PS等多种塑料的降解机制还不明确, 因此应结合多学科交叉方法和多组学技术开展MPs的物理、化学和生物学降解机制研究, 明确功能基因和关键降解酶的作用位点, 构建多种MPs的降解功能菌群, 为环境中MPs污染的有效阻控提供理论支撑.
4 结论土壤MPs对植物的毒性主要通过3个途径：植物对MPs的吸收、MPs分解释放内源污染物、MPs与环境污染物联合毒性.土壤MPs会直接在植物根系表面及体内积累, 损伤植物根系、影响植物对养分的吸收, 甚至造成细胞死亡.MPs在物理、化学和生物共同作用降解的过程中释放邻苯二甲酸盐酯、双酚A、壬基酚、溴化阻燃剂和有机磷酸酯类阻燃剂等添加剂, 这些内源污染物的释放使植物生长受到抑制甚至死亡.同时, MPs具有较大的表面积, 可以吸附环境中的重金属、有机污染物并增强其生物有效性和毒性效应.土壤MPs降解过程中产生的次生MPs及副产物是其对植物产生毒性的重要原因.对MPs降解研究进行解析, 发现自然环境中机械降解和化学降解主要影响MPs颗粒的大小和表面性质, 微生物降解主要完成MPs的矿化过程, 但对各降解机制的研究尚在初始阶段, 如PP、PVC和PS的降解机制并不明确, 其中间产物还未确定, 无法进一步了解MPs对陆生植物的间接毒性并提出有效改善措施.
致谢: 刘桂明、李一凡和汪翔宇等在论文写作与修改中提供帮助, 在此一并致谢！
| [1] | Plastic Europe. Plastics-the facts 2021[EB/OL]. https://plasticseurope.org/knowledge-hub/plastics-the-facts-2021/, 2022-12-25. |
| [2] |
国家统计局. 2021中国统计年鉴[M]. 北京: 中国统计出版社, 2021. National Bureau of Statistics. 2021 China statistical yearbook[M]. Beijing: China Statistics Press, 2021. |
| [3] | Chia W Y, Tang D Y Y, Khoo K S, et al. Nature's fight against plastic pollution: algae for plastic biodegradation and bioplastics production[J]. Environmental Science and Ecotechnology, 2020, 4. DOI:10.1016/j.ese.2020.100065 |
| [4] | Plastic Europe. Plastics-the facts 2015[EB/OL]. https://plasticseurope.org/knowledge-hub/plastics-the-facts-2015/, 2022-12-25. |
| [5] | de Souza Machado A A, Lau C W, Till J, et al. Impacts of microplastics on the soil biophysical environment[J]. Environmental Science & Technology, 2018, 52(17): 9656-9665. |
| [6] | de Souza Machado A A, Kloas W, Zarfl C, et al. Microplastics as an emerging threat to terrestrial ecosystems[J]. Global Change Biology, 2018, 24(4): 1405-1416. DOI:10.1111/gcb.14020 |
| [7] | Thompson R C, Olsen Y, Mitchell R P, et al. Lost at sea: where is all the plastic?[J]. Science, 2004, 304(5672): 838. DOI:10.1126/science.1094559 |
| [8] | Zhou X X, Liu R, Hao L T, et al. Identification of polystyrene nanoplastics using surface enhanced Raman spectroscopy[J]. Talanta, 2021, 221. DOI:10.1016/j.talanta.2020.121552 |
| [9] | 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. |
| [10] | Lv W W, Zhou W Z, Lu S B, et al. Microplastic pollution in rice-fish co-culture system: a report of three farmland stations in Shanghai, China[J]. Science of the Total Environment, 2019, 652: 1209-1218. DOI:10.1016/j.scitotenv.2018.10.321 |
| [11] | Amrutha K, Warrier A K. The first report on the source-to-sink characterization of microplastic pollution from a riverine environment in tropical India[J]. Science of the Total Environment, 2020, 739. DOI:10.1016/j.scitotenv.2020.140377 |
| [12] |
张起源. 湛江红树林湿地沉积物微塑料和三种有机污染物污染状况研究[D]. 广州: 暨南大学, 2020. Zhang Q Y. The research of pollution status and ecological risk about microplastics and three POPs in Zhanjiang Mangroves, China[D]. Guangzhou: Jinan University, 2020. |
| [13] | Bosker T, Bouwman L J, Brun N R, et al. Microplastics accumulate on pores in seed capsule and delay germination and root growth of the terrestrial vascular plant Lepidium sativum[J]. Chemosphere, 2019, 226: 774-781. DOI:10.1016/j.chemosphere.2019.03.163 |
| [14] | Li Z X, Li Q F, Li R J, et al. The distribution and impact of polystyrene nanoplastics on cucumber plants[J]. Environmental Science and Pollution Research, 2021, 28(13): 16042-16053. DOI:10.1007/s11356-020-11702-2 |
| [15] | Wang F Y, Zhang X Q, Zhang S Q, et al. Interactions of microplastics and cadmium on plant growth and arbuscular mycorrhizal fungal communities in an agricultural soil[J]. Chemosphere, 2020, 254. DOI:10.1016/j.chemosphere.2020.126791 |
| [16] | 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. DOI:10.1016/j.chemosphere.2020.128612 |
| [17] | Yang C, Gao X H. Impact of microplastics from polyethylene and biodegradable mulch films on rice(Oryza sativa L.)[J]. Science of the Total Environment, 2022, 828. DOI:10.1016/j.scitotenv.2022.154579 |
| [18] | Zhang J W, Huang D Y, Deng H, et al. Responses of submerged plant Vallisneria natans growth and leaf biofilms to water contaminated with microplastics[J]. Science of the Total Environment, 2022, 818. DOI:10.1016/j.scitotenv.2021.151750 |
| [19] | Boots B, Russell C W, Green D S. Effects of microplastics in soil ecosystems: above and below ground[J]. Environmental Science & Technology, 2019, 53(19): 11496-11506. |
| [20] | Wu X, Hou H J, Liu Y, et al. Microplastics affect rice(Oryza sativa L.) quality by interfering metabolite accumulation and energy expenditure pathways: a field study[J]. Journal of Hazardous Materials, 2022, 422. DOI:10.1016/j.jhazmat.2021.126834 |
| [21] |
李连祯, 周倩, 尹娜, 等. 食用蔬菜能吸收和积累微塑料[J]. 科学通报, 2019, 64(9): 928-934. Li L Z, Zhou Q, Yin N, et al. Uptake and accumulation of microplastics in an edible plant[J]. Chinese Science Bulletin, 2019, 64(9): 928-934. |
| [22] | Xu G H, Liu Y, Yu Y. Effects of polystyrene microplastics on uptake and toxicity of phenanthrene in soybean[J]. Science of the Total Environment, 2021, 783. DOI:10.1016/j.scitotenv.2021.147016 |
| [23] | Liu Y Y, Xu F J, Ding L P, et al. Microplastics reduce nitrogen uptake in peanut plants by damaging root cells and impairing soil nitrogen cycling[J]. Journal of Hazardous Materials, 2023, 443. DOI:10.1016/j.jhazmat.2022.130384 |
| [24] | de Souza Machado A A, Lau C W, Kloas W, et al. Microplastics can change soil properties and affect plant performance[J]. Environmental Science & Technology, 2019, 53(10): 6044-6052. |
| [25] | Li L Z, Luo Y M, Li R J, et al. Effective uptake of submicrometre plastics by crop plants via a crack-entry mode[J]. Nature Sustainability, 2020, 3(11): 929-937. DOI:10.1038/s41893-020-0567-9 |
| [26] | Li L Z, Luo Y M, Peijnenburg W J G M, et al. Confocal measurement of microplastics uptake by plants[J]. MethodsX, 2020, 7. DOI:10.1016/j.mex.2019.11.023 |
| [27] | Bandmann V, Müller J D, Kühler T, et al. Uptake of fluorescent nano beads into BY2-cells involves clathrin-dependent and clathrin-independent endocytosis[J]. FEBS Letters, 2012, 586(20): 3626-3632. DOI:10.1016/j.febslet.2012.08.008 |
| [28] | Li M Y, Zhang Y, Li C Y, et al. Polyvinyl chloride nanoparticles affect cell membrane integrity by disturbing the properties of the multicomponent lipid bilayer in Arabidopsis thaliana[J]. Molecules, 2022, 27(18). DOI:10.3390/molecules27185906 |
| [29] | Hollóczki O, Gehrke S. Nanoplastics can change the secondary structure of proteins[J]. Scientific Reports, 2019, 9(1). DOI:10.1038/s41598-019-52495-w |
| [30] | Giorgetti L, Spanò C, Muccifora S, et al. Exploring the interaction between polystyrene nanoplastics and Allium cepa during germination: internalization in root cells, induction of toxicity and oxidative stress[J]. Plant Physiology and Biochemistry, 2020, 149: 170-177. DOI:10.1016/j.plaphy.2020.02.014 |
| [31] | Kokalj A J, Kuehnel D, Puntar B, et al. An exploratory ecotoxicity study of primary microplastics versus aged in natural waters and wastewaters[J]. Environmental Pollution, 2019, 254. DOI:10.1016/j.envpol.2019.112980 |
| [32] | Sun X D, Yuan X Z, Jia Y B, et al. Differentially charged nanoplastics demonstrate distinct accumulation in Arabidopsis thaliana[J]. Nature Nanotechnology, 2020, 15(9): 755-760. DOI:10.1038/s41565-020-0707-4 |
| [33] | Jiang X F, Chen H, Liao Y C, et al. Ecotoxicity and genotoxicity of polystyrene microplastics on higher plant Vicia faba[J]. Environmental Pollution, 2019, 250: 831-838. DOI:10.1016/j.envpol.2019.04.055 |
| [34] | Lozano Y M, Lehnert T, Linck L T, et al. Microplastic shape, polymer type, and concentration affect soil properties and plant biomass[J]. Frontiers in Plant Science, 2021, 12. DOI:10.3389/fpls.2021.616645 |
| [35] | Zhang G S, Zhang F X, Li X T. Effects of polyester microfibers on soil physical properties: perception from a field and a pot experiment[J]. Science of the Total Environment, 2019, 670: 1-7. DOI:10.1016/j.scitotenv.2019.03.149 |
| [36] |
王志超, 张博文, 倪嘉轩, 等. 微塑料对土壤水分入渗和蒸发的影响[J]. 环境科学, 2022, 43(8): 4394-4401. Wang Z C, Zhang B W, Ni J X, et al. Effect of microplastics on soil water infiltration and evaporation[J]. Environmental Science, 2022, 43(8): 4394-4401. DOI:10.13227/j.hjkx.202111292 |
| [37] | Sun M X, Liu X L, Shi K W, et al. Effects of root zone aeration on soil microbes species in a peach tree rhizosphere and root growth[J]. Microorganisms, 2022, 10(10). DOI:10.3390/microorganisms10101879 |
| [38] | Lozano Y M, Lehnert T, Linck L T, et al. Microplastic shape, polymer type, and concentration affect soil properties and plant biomass[J]. Frontiers in Plant Science, 2021, 12. DOI:10.3389/fpls.2021.714541 |
| [39] | Wan Y, Wu C X, Xue Q, et al. Effects of plastic contamination on water evaporation and desiccation cracking in soil[J]. Science of the Total Environment, 2019, 654: 576-582. DOI:10.1016/j.scitotenv.2018.11.123 |
| [40] | Qi Y L, Ossowicki A, Yang X M, et al. Effects of plastic mulch film residues on wheat rhizosphere and soil properties[J]. Journal of Hazardous Materials, 2020, 387. DOI:10.1016/j.jhazmat.2019.121711 |
| [41] | Meng F R, Yang X M, Riksen M, et al. Response of common bean(Phaseolus vulgaris L.) growth to soil contaminated with microplastics[J]. Science of the Total Environment, 2021, 755. DOI:10.1016/j.scitotenv.2020.142516 |
| [42] | Lehmann A, Leifheit E F, Feng L S, et al. Microplastic fiber and drought effects on plants and soil are only slightly modified by arbuscular mycorrhizal fungi[J]. Soil Ecology Letters, 2022, 4(1): 32-44. DOI:10.1007/s42832-020-0060-4 |
| [43] | Ouyang Z Z, Zhang Z P, Jing Y, et al. The photo-aging of polyvinyl chloride microplastics under different UV irradiations[J]. Gondwana Research, 2022, 108: 72-80. DOI:10.1016/j.gr.2021.07.010 |
| [44] | 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. DOI:10.1016/j.envpol.2019.113475 |
| [45] | 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. |
| [46] | Rozman U, Turk T, Skalar T, et al. An extensive characterization of various environmentally relevant microplastics-Material properties, leaching and ecotoxicity testing[J]. Science of the Total Environment, 2021, 773. DOI:10.1016/j.scitotenv.2021.145576 |
| [47] | Cheng Z P, Wang Y, Qiao B T, et al. Insights into mechanisms involved in the uptake, translocation, and metabolism of phthalate esters in Chinese cabbage(Brassica rapa var. chinensis)[J]. Science of the Total Environment, 2021, 768. DOI:10.1016/j.scitotenv.2021.144945 |
| [48] | Jiang L F, Zhu X P, Luo C L, et al. The synergistic toxicity effect of di(2-ethylhexyl)phthalate and plant growth disturbs the structure and function of soil microbes in the rhizosphere[J]. Environment International, 2022, 170. DOI:10.1016/j.envint.2022.107629 |
| [49] |
李海峰, 刘河疆, 任红松, 等. 邻苯二甲酸酯对葡萄植株生长及物质构成的影响[J]. 江西农业学报, 2021, 33(6): 25-28, 33. Li H F, Liu H J, Ren H S, et al. Effects of phthalates on growth and material composition of grape plants[J]. Acta Agriculturae Jiangxi, 2021, 33(6): 25-28, 33. DOI:10.19386/j.cnki.jxnyxb.2021.06.005 |
| [50] | Wang F, Zhang M, Sha W, et al. Sorption behavior and mechanisms of organic contaminants to nano and microplastics[J]. Molecules, 2020, 25(8). DOI:10.3390/molecules25081827 |
| [51] | Chen C C, Zhu X S, Xu H, et al. Copper adsorption to microplastics and natural particles in seawater: a comparison of kinetics, isotherms, and bioavailability[J]. Environmental Science & Technology, 2021, 55(20): 13923-13931. |
| [52] |
王一飞, 李淼, 于海瀛, 等. 微塑料对环境中有机污染物吸附解吸的研究进展[J]. 生态毒理学报, 2019, 14(4): 23-30. Wang Y F, Li M, Yu H Y, et al. Research progress on the adsorption and desorption between microplastics and environmental organic pollutants[J]. Asian Journal of Ecotoxicology, 2019, 14(4): 23-30. |
| [53] | Okoffo E D, O'Brien S, O'Brien J W, et al. Wastewater treatment plants as a source of plastics in the environment: a review of occurrence, methods for identification, quantification and fate[J]. Environmental Science: Water Research & Technology, 2019, 5(11): 1908-1931. |
| [54] |
孙聪惠. 渤海湾滨海潮间带微塑料和重金属污染及生态风险[D]. 天津: 天津师范大学, 2018. Sun C H. Microplastics and heavy metal pollution in the intertidal zone of Bohai Bay and its ecological risks[D]. Tianjin: Tianjin Normal University, 2018. |
| [55] | Abbasi S, Moore F, Keshavarzi B, et al. PET-microplastics as a vector for heavy metals in a simulated plant rhizosphere zone[J]. Science of the Total Environment, 2020, 744. DOI:10.1016/j.scitotenv.2020.140984 |
| [56] | Zeb A, Liu W T, Meng L Z, et al. Effects of polyester microfibers(PMFs) and cadmium on lettuce(Lactuca sativa) and the rhizospheric microbial communities: a study involving physio-biochemical properties and metabolomic profiles[J]. Journal of Hazardous Materials, 2022, 424. DOI:10.1016/j.jhazmat.2021.127405 |
| [57] | Dong Y M, Gao M L, Song Z G, et al. Microplastic particles increase arsenic toxicity to rice seedlings[J]. Environmental Pollution, 2020, 259. DOI:10.1016/j.envpol.2019.113892 |
| [58] | Zhang S W, Han B, Sun Y H, et al. Microplastics influence the adsorption and desorption characteristics of Cd in an agricultural soil[J]. Journal of Hazardous Materials, 2020, 388. DOI:10.1016/j.jhazmat.2019.121775 |
| [59] |
顾馨悦, 徐修媛, 咸泽禹, 等. 老化聚氯乙烯微塑料与镉对小麦的联合毒性[J]. 环境化学, 2021, 40(9): 2633-2639. Gu X Y, Xu X Y, Xian Z Y, et al. Joint toxicity of aged polyvinyl chloride microplastics and cadmium to the wheat plant[J]. Environmental Chemistry, 2021, 40(9): 2633-2639. |
| [60] | Lian J P, Wu J N, Zeb A, et al. Do polystyrene nanoplastics affect the toxicity of cadmium to wheat(Triticum aestivum L.)?[J]. Environmental Pollution, 2020, 263. DOI:10.1016/j.envpol.2020.114498 |
| [61] | Yu H, Hou J H, Dang Q L, et al. Decrease in bioavailability of soil heavy metals caused by the presence of microplastics varies across aggregate levels[J]. Journal of Hazardous Materials, 2020, 395. DOI:10.1016/j.jhazmat.2020.122690 |
| [62] |
徐擎擎, 张哿, 邹亚丹, 等. 微塑料与有机污染物的相互作用研究进展[J]. 生态毒理学报, 2018, 13(1): 40-49. Xu Q Q, Zhang G, Zou Y D, et al. Interactions between microplastics and organic pollutants: current status and knowledge gaps[J]. Asian Journal of Ecotoxicology, 2018, 13(1): 40-49. |
| [63] | Šunta U, Prosenc F, Trebše P, et al. Adsorption of acetamiprid, chlorantraniliprole and flubendiamide on different type of microplastics present in alluvial soil[J]. Chemosphere, 2020, 261. DOI:10.1016/j.chemosphere.2020.127762 |
| [64] | Hu X J, Yu Q, Waigi M G, et al. Microplastics-sorbed phenanthrene and its derivatives are highly bioaccessible and may induce human cancer risks[J]. Environment International, 2022, 168. DOI:10.1016/j.envint.2022.107459 |
| [65] | Wang L C, Lin J C T, Dong C D, et al. The sorption of persistent organic pollutants in microplastics from the coastal environment[J]. Journal of Hazardous Materials, 2021, 420. DOI:10.1016/j.jhazmat.2021.126658 |
| [66] | Zhang C L, Lei Y C, Qian J, et al. Sorption of organochlorine pesticides on polyethylene microplastics in soil suspension[J]. Ecotoxicology and Environmental Safety, 2021, 223. DOI:10.1016/j.ecoenv.2021.112591 |
| [67] | Wang T, Yu C C, Chu Q, et al. Adsorption behavior and mechanism of five pesticides on microplastics from agricultural polyethylene films[J]. Chemosphere, 2020, 244. DOI:10.1016/j.chemosphere.2019.125491 |
| [68] | Wang Y, Wang X J, Li Y, et al. Effects of exposure of polyethylene microplastics to air, water and soil on their adsorption behaviors for copper and tetracycline[J]. Chemical Engineering Journal, 2021, 404. DOI:10.1016/j.cej.2020.126412 |
| [69] | 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 |
| [70] |
刘海朱, 王隽媛, 路思远, 等. 微塑料对有机污染物的吸附及微塑料-有机物复合污染的毒性研究进展[J]. 环境生态学, 2020, 2(12): 89-94. Liu H Z, Wang J Y, Lu S Y, et al. Research progress on adsorption of organic pollutants by microplastics and toxicity of microplastic-organic compound pollution[J]. Environmental Ecology, 2020, 2(12): 89-94. |
| [71] |
王胜利, 宋正国, 王成伟, 等. 聚苯乙烯与邻苯二甲酸二丁酯共存对紫叶生菜的毒性效应[J]. 应用生态学报, 2021, 32(9): 3335-3340. Wang S L, Song Z G, Wang C W, et al. Toxic effects of polystyrene and dibutyl phthalate on purple lettuce[J]. Chinese Journal of Applied Ecology, 2021, 32(9): 3335-3340. |
| [72] |
单宁, 祖木热提·艾比布, 米丽班·霍加艾合买提, 等. 微塑料对黑麦草吸收和累积水体中环丙沙星的影响[J]. 环境科学研究, 2020, 33(12): 2906-2912. Shan N, Habibul Z, Hojahmat M, et al. Effects of microplastics on ryegrass(Lolium perenne L.) uptake and accumulation of ciprofloxacin[J]. Research of Environmental Sciences, 2020, 33(12): 2906-2912. |
| [73] | 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. |
| [74] | Chen Q D, Wang Q, Zhang C, et al. Aging simulation of thin-film plastics in different environments to examine the formation of microplastic[J]. Water Research, 2021, 202. DOI:10.1016/j.watres.2021.117462 |
| [75] | Niu L H, Li Y Y, Li Y, et al. New insights into the vertical distribution and microbial degradation of microplastics in urban river sediments[J]. Water Research, 2021, 188. DOI:10.1016/j.watres.2020.116449 |
| [76] | Oberbeckmann S, Labrenz M. Marine microbial assemblages on microplastics: diversity, adaptation, and role in degradation[J]. Annual Review of Marine Science, 2020, 12(1): 209-232. |
| [77] | 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. |
| [78] | Zhang K, Hamidian A H, Tubić A, et al. Understanding plastic degradation and microplastic formation in the environment: a review[J]. Environmental Pollution, 2021, 274. DOI:10.1016/j.envpol.2021.116554 |
| [79] | Huerta Lwanga E, Thapa B, Yang X M, et al. Decay of low-density polyethylene by bacteria extracted from earthworm's guts: a potential for soil restoration[J]. Science of the Total Environment, 2018, 624: 753-757. |
| [80] | Sangale M K, Shahnawaz M, Ade A B. Potential of fungi isolated from the dumping sites mangrove rhizosphere soil to degrade polythene[J]. Scientific Reports, 2019, 9(1). DOI:10.1038/s41598-019-41448-y |
| [81] | 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. DOI:10.1016/j.scitotenv.2020.136862 |
| [82] | Liu Z Y, Zhu Y J, Lv S S, et al. Quantifying the dynamics of polystyrene microplastics UV-aging process[J]. Environmental Science & Technology Letters, 2022, 9(1): 50-56. |
| [83] | Mundhenke T F, Li S C, Maurer-Jones M A. Photodegradation of polyolefin thin films in simulated freshwater conditions[J]. Environmental Science: Processes & Impacts, 2022, 24(12): 2284-2293. |
| [84] | 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. DOI:10.1016/j.jhazmat.2020.122515 |
| [85] | Ainali N M, Bikiaris D N, Lambropoulou D A. Aging effects on low- and high-density polyethylene, polypropylene and polystyrene under UV irradiation: an insight into decomposition mechanism by Py-GC/MS for microplastic analysis[J]. Journal of Analytical and Applied Pyrolysis, 2021, 158. DOI:10.1016/j.jaap.2021.105207 |
| [86] | 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. DOI:10.1016/j.scitotenv.2021.149840 |
| [87] | Pischedda A, Tosin M, Degli-Innocenti F. Biodegradation of plastics in soil: the effect of temperature[J]. Polymer Degradation and Stability, 2019, 170. DOI:10.1016/j.polymdegradstab.2019.109017 |
| [88] | Rillig M C, Ingraffia R, De Souza Machado A A. Microplastic incorporation into soil in agroecosystems[J]. Frontiers in Plant Science, 2017, 8. DOI:10.3389/fpls.2017.01805 |
| [89] | Tiwari N, Santhiya D, Sharma J G. Microbial remediation of micro-nano plastics: current knowledge and future trends[J]. Environmental Pollution, 2020, 265. DOI:10.1016/j.envpol.2020.115044 |
| [90] | Jadaun J S, Bansal S, Sonthalia A, et al. Biodegradation of plastics for sustainable environment[J]. Bioresource Technology, 2022, 347. DOI:10.1016/j.biortech.2022.126697 |
| [91] | 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. DOI:10.1016/j.jhazmat.2020.122596 |
| [92] | 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. |
| [93] | Ali S S, Elsamahy T, Al-Tohamy R, et al. Plastic wastes biodegradation: mechanisms, challenges and future prospects[J]. Science of the Total Environment, 2021, 780. DOI:10.1016/j.scitotenv.2021.146590 |
| [94] |
刘治君, 杨凌肖, 王琼, 等. 微塑料在陆地水环境中的迁移转化与环境效应[J]. 环境科学与技术, 2018, 41(4): 59-65, 90. Liu Z J, Yang L X, Wang Q, et al. Migration and transformation of microplastics in terrestrial waters and effects on eco-environment[J]. Environmental Science & Technology, 2018, 41(4): 59-65, 90. |
| [95] | Zhang Z, Peng H R, Yang D C, et al. Polyvinyl chloride degradation by a bacterium isolated from the gut of insect larvae[J]. Nature Communications, 2022, 13(1). DOI:10.1038/s41467-022-32903-y |
| [96] | Han X, Liu W, Huang J W, et al. Structural insight into catalytic mechanism of PET hydrolase[J]. Nature Communications, 2017, 8. DOI:10.1038/s41467-017-02255-z |
| [97] | Ahmed T, Shahid M, Azeem F, et al. Biodegradation of plastics: current scenario and future prospects for environmental safety[J]. Environmental Science and Pollution Research, 2018, 25(8): 7287-7298. |
| [98] | Zhang J Q, Gao D L, Li Q H, et al. Biodegradation of polyethylene microplastic particles by the fungus Aspergillus flavus from the guts of wax moth Galleria mellonella[J]. Science of the Total Environment, 2020, 704. DOI:10.1016/j.scitotenv.2019.135931 |
| [99] | Yuan J H, Ma J, Sun Y R, et al. Microbial degradation and other environmental aspects of microplastics/plastics[J]. Science of the Total Environment, 2020, 715. DOI:10.1016/j.scitotenv.2020.136968 |
| [100] | Ng E L, Lwanga E H, Eldridge S M, et al. An overview of microplastic and nanoplastic pollution in agroecosystems[J]. Science of the Total Environment, 2018, 627: 1377-1388. |
| [101] | Kawai F, Kawabata T, Oda M. Current knowledge on enzymatic PET degradation and its possible application to waste stream management and other fields[J]. Applied Microbiology and Biotechnology, 2019, 103(11): 4253-4268. |
| [102] | Danso D, Schmeisser C, Chow J, et al. New insights into the function and global distribution of polyethylene terephthalate(PET)-degrading bacteria and enzymes in marine and terrestrial metagenomes[J]. Applied and Environmental Microbiology, 2018, 84(8). DOI:10.1128/AEM.02773-17 |
| [103] | Gan Z Q, Zhang H J. PMBD: a comprehensive plastics microbial biodegradation database[J]. Database, 2019, 2019. DOI:10.1093/database/baz119 |
| [104] | Kim N K, Lee S H, Park H D. Current biotechnologies on depolymerization of polyethylene terephthalate(PET) and repolymerization of reclaimed monomers from PET for bio-upcycling: a critical review[J]. Bioresource Technology, 2022, 363. DOI:10.1016/j.biortech.2022.127931 |
| [105] | Dey A S, Bose H, Mohapatra B, et al. Biodegradation of unpretreated low-density polyethylene(LDPE) by Stenotrophomonas sp. and Achromobacter sp., isolated from waste dumpsite and drilling fluid[J]. Frontiers in Microbiology, 2020, 11. DOI:10.3389/fmicb.2020.603210 |
| [106] | Sangeetha Devi R, Ramya R, Kannan K, et al. Investigation of biodegradation potentials of high density polyethylene degrading marine bacteria isolated from the coastal regions of Tamil Nadu, India[J]. Marine Pollution Bulletin, 2019, 138: 549-560. |
| [107] | Montazer Z, Habibi Najafi M B, Levin D B. Challenges with verifying microbial degradation of polyethylene[J]. Polymers, 2020, 12(1). DOI:10.3390/polym12010123 |
| [108] | Ghatge S, Yang Y R, Ahn J H, et al. Biodegradation of polyethylene: a brief review[J]. Applied Biological Chemistry, 2020, 63(1). DOI:10.1186/s13765-020-00511-3 |
| [109] | Kang B R, Kim S B, Song H A, et al. Accelerating the biodegradation of high-density polyethylene(HDPE) using Bjerkandera adusta TBB-03 and lignocellulose substrates[J]. Microorganisms, 2019, 7(9). DOI:10.3390/microorganisms7090304 |
| [110] | Bardají D K R, Furlan J P R, Stehling E G. Isolation of a polyethylene degrading Paenibacillus sp. from a landfill in Brazil[J]. Archives of Microbiology, 2019, 201(5): 699-704. |
| [111] | Auta H S, Emenike C U, Jayanthi B, et al. Growth kinetics and biodeterioration of polypropylene microplastics by Bacillus sp. and Rhodococcus sp. isolated from mangrove sediment[J]. Marine Pollution Bulletin, 2018, 127: 15-21. |
| [112] | Giacomucci L, Raddadi N, Soccio M, et al. Polyvinyl chloride biodegradation by Pseudomonas citronellolis and Bacillus flexus[J]. New Biotechnology, 2019, 52: 35-41. |
| [113] | Urbanek A K, Rybak J, Wróbel M, et al. A comprehensive assessment of microbiome diversity in Tenebrio molitor fed with polystyrene waste[J]. Environmental Pollution, 2020, 262. DOI:10.1016/j.envpol.2020.114281 |
| [114] | Vivi V K, Martins-Franchetti S M, Attili-Angelis D. Biodegradation of PCL and PVC: Chaetomium globosum(ATCC 16021) activity[J]. Folia Microbiologica, 2019, 64(1): 1-7. |
| [115] | Skariyachan S, Setlur A S, Naik S Y, et al. Enhanced biodegradation of low and high-density polyethylene by novel bacterial consortia formulated from plastic-contaminated cow dung under thermophilic conditions[J]. Environmental Science and Pollution Research, 2017, 24(9): 8443-8457. |
| [116] | Sánchez C. Fungal potential for the degradation of petroleum-based polymers: an overview of macro- and microplastics biodegradation[J]. Biotechnology Advances, 2020, 40. DOI:10.1016/j.biotechadv.2019.107501 |
| [117] | Lou Y, Ekaterina P, Yang S S, et al. Biodegradation of polyethylene and polystyrene by greater wax moth larvae(Galleria mellonella L.) and the effect of co-diet supplementation on the core gut microbiome[J]. Environmental Science & Technology, 2020, 54(5): 2821-2831. |
| [118] |
高超, 郝孔利, 赵宇婷, 等. 一株能够降解聚乙烯的霍氏肠杆菌的鉴定及分析[J]. 生物技术通报, 2020, 36(10): 99-104. Gao C, Hao K L, Zhao Y T, et al. Identification and analysis of a strain of enterobacter hormaechei capable of degrading polyethylene[J]. Biotechnology Bulletin, 2020, 36(10): 99-104. |
| [119] | Wang Z, Xin X, Shi X F, et al. A polystyrene-degrading Acinetobacter bacterium isolated from the larvae of Tribolium castaneum[J]. Science of the Total Environment, 2020, 726. DOI:10.1016/j.scitotenv.2020.138564 |
| [120] | Auta H S, Abioye O P, Aransiola S A, et al. Enhanced microbial degradation of PET and PS microplastics under natural conditions in mangrove environment[J]. Journal of Environmental Management, 2022, 304. DOI:10.1016/j.jenvman.2021.114273 |
| [121] | Auta H S, Emenike C U, Fauziah S H. Screening of Bacillus strains isolated from mangrove ecosystems in Peninsular Malaysia for microplastic degradation[J]. Environmental Pollution, 2017, 231: 1552-1559. |
| [122] | Chaudhary A K, Vijayakumar R P. Studies on biological degradation of polystyrene by pure fungal cultures[J]. Environment, Development and Sustainability, 2020, 22(5): 4495-4508. |