滨海河口潮滩中微塑料的表面风化和成分变化
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摘要
微塑料作为新兴环境污染物日益受到关注,但对真实环境中不同类型微塑料的表面形貌、成分及其变化了解甚少,相应的方法学研究多处于探索阶段.本研究以受人类活动强烈影响的黄渤海沿岸河口潮滩为对象,运用多种显微技术和微分析方法,研究了微塑料类型、表面形貌及其成分变化.采用光学显微镜和扫描电子显微镜(scanning electron microscope,SEM)分析表明,潮滩环境中微塑料除了碎片、纤维、薄膜等形貌类型外,还存在发泡类和树脂类颗粒.表面呈现不同形状和大小的皱褶、微孔、裂纹或凸起等,可能受到了机械摩檫、化学氧化或生物侵蚀等作用.运用衰减全反射傅里叶变换红外光谱仪(attenuated total reflection Fourier transform infrared spectroscopy,ATR-FT-IR),在分析微塑料聚合物成分的基础上,鉴定出潮滩环境中微塑料表面具有羧酸、醛、酯或酮类等含氧官能团.通过裂解气相色谱-质谱(pyrolysis gas chromatography-mass spectrometry,pyr-GC-MS)不仅鉴定出纤维类微塑料是聚乙烯与聚丙烯共混聚合物,还观测到发泡类风化表层与剥离风化表层后的内部之间的成分差异,其中,油酸腈、芥酸酰胺、ɑ-N-去甲基美沙醇、1,1-二苯基-螺[2,3]-己烷-5-羧酸甲酯、棕榈酸十八酯和棕榈酸十六酯等含氧、含氮化学物为风化表层特有,进一步证实了河口潮滩环境中微塑料表面含氧物质的存在.由此可见,环境中微塑料表面在风化的同时还发生了成分的变化.未来应关注海岸和海洋中微塑料的表面变化过程和生态环境效应研究.
Microplastics are a type of emerging environmental pollutant that has been the subject of increasing concern worldwide.The surface morphology,composition and changes in the distribution of microplastics in the environment are poorly understood.The corresponding research methodology is also at the exploratory stage.Here,we examine typical estuarine sediments from Shandong Province,east China,that are influenced by intensive human activity.The microplastics are separated from the sediments using an apparatus of continuous flow and floating separation.The microplastics samples are processed to determine the types,morphology and changing composition of microplastics present using a range of advanced microscopic and microanalytical methods.The aim is to understand the weathering and subsequent surface changes in the microplastics under the environmental conditions of estuarine sediments.Optical microscope and scanning electron microscope-energy spectrum(SEM-EDS) analysis shows that foams and pellets,together with fragments,fibers and films,are present in the estuarine sediments.The five shape types of microplastics had different weathering surface morphologies compared to the corresponding large plastic debris from the same sampling sites and to the corresponding commercial plastic products.The surfaces of the commercial products are smooth.The surfaces of plastic debris appear to be slightly broken and aged while the surface of microplastics from the same sites show many more microholes,cracks or protuberances.This indicates that the surfaces of microplastics on the estuarine beaches have been strongly weathered.Scratches,creases,microholes,cracks,either concave or convex and of various shapes and sizes were found on the surfaces of microplastics from the coastal environment,possibly due to mechanical friction,chemical oxidation and/or biological attack.Attenuated total reflection Fourier transform infrared spectroscopy(ATR-FT-IR) was used to find oxygen-containing functional groups such as carboxylic acids,aldehydes and esters or ketones on the microplastic surfaces from the tidal flats on the basis of polymer component analysis.The two selected shape types,namely foams and fragments from soft plastic woven bags,had different infrared spectra than their corresponding large plastic debris from the same sampling sites and to the original commercial plastic products.The surfaces of these two microplastics had more complicated infrared spectra near the fingerprint area.This implies that the aging process of large plastic debris may be an important source of microplastics in the environment.A polymer blend of both polyethylene and polypropylene was identified in the fibers using pyrolysis gas chromatography-mass spectrometry(pyr-GC-MS).The pyr-GC-MS analysis also indicates that the pyrolysis products were much common on the aged surfaces of foams from the beach than on the inner part of foams after removal of the aged surfaces,including mainly compounds containing oxygen or nitrogen such as oleanitrile,trans-13-docosenamide,α-n-normethadol:1,1-diphenyl-spiro[2,3] hexane-5-carboxylic acid,methyl ester,hexadecanoic acid,octadecyl ester and hexadecanoic acid,hexadecyl ester.The surficial morphology,composition and possible properties of microplastics from the estuarine beaches were clearly different from those of the original commercial plastic products.We suggest that surface weathering can cause changes in the surface components of microplastics under the actual conditions prevailing on coastal beaches.By observation of the weathering of microplastic surfaces it is difficult,using a single identification method,to distinguish between finer polymer components,particularly in samples of blends or copolymers.This study shows that pyr-GC-MS can be used directly to obtain and verify the specific weathering products of microplastics and the ATR-FT-IR may be used as an ancillary tool for recognition of microplastics in the environment.Much effort needs to be devoted in the future to understanding the changes in surface processes,ecological and environmental effects,and methods of identification of microplastic particles in coastal and oceanic environments.
Microplastics are a type of emerging environmental pollutant that has been the subject of increasing concern worldwide.The surface morphology,composition and changes in the distribution of microplastics in the environment are poorly understood.The corresponding research methodology is also at the exploratory stage.Here,we examine typical estuarine sediments from Shandong Province,east China,that are influenced by intensive human activity.The microplastics are separated from the sediments using an apparatus of continuous flow and floating separation.The microplastics samples are processed to determine the types,morphology and changing composition of microplastics present using a range of advanced microscopic and microanalytical methods.The aim is to understand the weathering and subsequent surface changes in the microplastics under the environmental conditions of estuarine sediments.Optical microscope and scanning electron microscope-energy spectrum(SEM-EDS) analysis shows that foams and pellets,together with fragments,fibers and films,are present in the estuarine sediments.The five shape types of microplastics had different weathering surface morphologies compared to the corresponding large plastic debris from the same sampling sites and to the corresponding commercial plastic products.The surfaces of the commercial products are smooth.The surfaces of plastic debris appear to be slightly broken and aged while the surface of microplastics from the same sites show many more microholes,cracks or protuberances.This indicates that the surfaces of microplastics on the estuarine beaches have been strongly weathered.Scratches,creases,microholes,cracks,either concave or convex and of various shapes and sizes were found on the surfaces of microplastics from the coastal environment,possibly due to mechanical friction,chemical oxidation and/or biological attack.Attenuated total reflection Fourier transform infrared spectroscopy(ATR-FT-IR) was used to find oxygen-containing functional groups such as carboxylic acids,aldehydes and esters or ketones on the microplastic surfaces from the tidal flats on the basis of polymer component analysis.The two selected shape types,namely foams and fragments from soft plastic woven bags,had different infrared spectra than their corresponding large plastic debris from the same sampling sites and to the original commercial plastic products.The surfaces of these two microplastics had more complicated infrared spectra near the fingerprint area.This implies that the aging process of large plastic debris may be an important source of microplastics in the environment.A polymer blend of both polyethylene and polypropylene was identified in the fibers using pyrolysis gas chromatography-mass spectrometry(pyr-GC-MS).The pyr-GC-MS analysis also indicates that the pyrolysis products were much common on the aged surfaces of foams from the beach than on the inner part of foams after removal of the aged surfaces,including mainly compounds containing oxygen or nitrogen such as oleanitrile,trans-13-docosenamide,α-n-normethadol:1,1-diphenyl-spiro[2,3] hexane-5-carboxylic acid,methyl ester,hexadecanoic acid,octadecyl ester and hexadecanoic acid,hexadecyl ester.The surficial morphology,composition and possible properties of microplastics from the estuarine beaches were clearly different from those of the original commercial plastic products.We suggest that surface weathering can cause changes in the surface components of microplastics under the actual conditions prevailing on coastal beaches.By observation of the weathering of microplastic surfaces it is difficult,using a single identification method,to distinguish between finer polymer components,particularly in samples of blends or copolymers.This study shows that pyr-GC-MS can be used directly to obtain and verify the specific weathering products of microplastics and the ATR-FT-IR may be used as an ancillary tool for recognition of microplastics in the environment.Much effort needs to be devoted in the future to understanding the changes in surface processes,ecological and environmental effects,and methods of identification of microplastic particles in coastal and oceanic environments.
引文
1 Fok L,Cheung P K.Hong Kong at the Pearl River Estuary:A hotspot of microplastic pollution.Mar Pollut Bull,2015,99:112-118
2 Veerasingam S,Saha M,Suneel V,et al.Characteristics,seasonal distribution and surface degradation features of microplastic pellets along the Goa coast,India.Chemosphere,2016,159:496-505
3 Zhou Q.Occurrences and ecological risks of microplastics in the typical coastal beaches and seas(in Chinese).Master Dissertation.Yantai:Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,2016[周倩.典型滨海潮滩及近海环境中微塑料污染特征与生态风险.硕士学位论文.烟台:中国科学院烟台海岸带研究所,2016]
4 Lee J,Hong S,Song Y K,et al.Relationships among the abundances of plastic debris in different size classes on beaches in South Korea.Mar Pollut Bull,2013,77:349-354
5 Lima A R A,Costa M F,Barletta M.Distribution patterns of microplastics within the plankton of a tropical estuary.Environ Res,2014,132:146-155
6 Zhang H B,Zhou Q,Luo Y M,et al.A method and apparatus of continuous flow and floating separation for microplastics(in Chinese).China Patent,201510227085.1,2016-12-07[章海波,周倩,骆永明,等.一种微颗粒塑料的连续流动分离浮选装置及方法.中国专利,201510227085.1,2016-12-07]
7 Zhou Q,Zhang H B,Zhou Y,et al.Separation of microplastics from a coastal soil and their surface microscopic features(in Chinese).Chin Sci Bull,2016,61:1604-1611[周倩,章海波,周阳,等.滨海潮滩土壤中微塑料的分离及其表面微观特征.科学通报,2016,61:1604-1611]
8 Corcoran P L,Biesinger M C,Grifi M.Plastics and beaches:A degrading relationship.Mar Pollut Bull,2009,58:80-84
9 Brandon J,Goldstein M,Ohman M D.Long-term aging and degradation of microplastic particles:Comparing in situ oceanic and experimental weathering patterns.Mar Pollut Bull,2016,110:299-308
10 Fries E,Dekiff J H,Willmeyer J,et al.Identification of polymer types and additives in marine microplastic particles using pyrolysis-GC/MS and scanning electron microscopy.Environ Sci Process Impact,2013,15:1949-1956
11 Zhou Y.Adsorption and partition pharacteristics of oxytetracycline by the microplastics in coastal environments(in Chinese).Master Dissertation.Yantai:Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,2017[周阳.海岸环境中微塑料对土霉素的吸附分配特征研究.硕士学位论文.烟台:中国科学院烟台海岸带研究所,2017]
12 Liao C C.Method of preparation and application of erucylamide.Cereals Oils,1993,(3):47-50[廖常聪.芥酸酰胺制法及其应用.粮食与油脂,1993,(3):47-50]
13 Rani M,Shim W J,Han G M,et al.Qualitative analysis of additives in plastic marine debris and its new products.Arch Environ Contam Toxicol,2015,69:352-366
14 Ashton K,Holmes L,Turner A.Association of metals with plastic production pellets in the marine environment.Mar Pollut Bull,2010,60:2050-2055
15 Ogata Y,Takada H,Mizukawa K,et al.International Pellet Watch:Global monitoring of persistent organic pollutants(POPs)in coastal waters.1.Initial phase data on PCBs,DDTs,and HCHs.Mar Pollut Bull,2009,58:1437-1446
16 Fischer M,Scholz-Bo?ttcher B M.Simultaneous trace identification and quantification of common types of microplastics in environmental samples by pyrolysis-Gas Chromatography-Mass Spectrometry.Environ Sci Technol,2017,51:5052-5060
17 Reisser J,Shaw J,Hallegraeff G,et al.Millimeter-sized marine plastics:A new pelagic habitat for microorganisms and invertebrates.PLo S One,2014,9:e100289
18 Fotopoulou K N,Vakros J,Karapanagioti H K.Surface properties of marine microplastics that affect their interaction with pollutants and microbes.In:CIESM Workshop Monographs No.46.Albania,2014.55-60
19 Set?l?O,Fleming-Lehtinen V,Lehtiniemi M.Ingestion and transfer of microplastics in the planktonic food web.Environ Pollut,2014,185:77-83
20 Farrell P,Nelson K.Trophic level transfer of microplastic:Mytilus edulis(L.)to Carcinus maenas(L.).Environ Pollut,2013,177:1-3
21 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.Sci Total Environ,2014,493:656-661
22 Zhou Q,Zhang H B,Li Y,et al.Research progress on microplastics pollution and its ecological effects in the coastal environment(in Chinese).Chin Sci Bull,2015,60:3210-3220[周倩,章海波,李远,等.海岸环境中微塑料污染及其生态效应研究进展.科学通报,2015,60:3210-3220]
23 Tsuge S,Ohtani H,Watanabe C.Pyrolysis-GC/MS Data Book of Synthetic Polymers:Pyrograms,Thermograms and MS of Pyrolyzates.Amsterdam:Elsevier,2011
2 Veerasingam S,Saha M,Suneel V,et al.Characteristics,seasonal distribution and surface degradation features of microplastic pellets along the Goa coast,India.Chemosphere,2016,159:496-505
3 Zhou Q.Occurrences and ecological risks of microplastics in the typical coastal beaches and seas(in Chinese).Master Dissertation.Yantai:Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,2016[周倩.典型滨海潮滩及近海环境中微塑料污染特征与生态风险.硕士学位论文.烟台:中国科学院烟台海岸带研究所,2016]
4 Lee J,Hong S,Song Y K,et al.Relationships among the abundances of plastic debris in different size classes on beaches in South Korea.Mar Pollut Bull,2013,77:349-354
5 Lima A R A,Costa M F,Barletta M.Distribution patterns of microplastics within the plankton of a tropical estuary.Environ Res,2014,132:146-155
6 Zhang H B,Zhou Q,Luo Y M,et al.A method and apparatus of continuous flow and floating separation for microplastics(in Chinese).China Patent,201510227085.1,2016-12-07[章海波,周倩,骆永明,等.一种微颗粒塑料的连续流动分离浮选装置及方法.中国专利,201510227085.1,2016-12-07]
7 Zhou Q,Zhang H B,Zhou Y,et al.Separation of microplastics from a coastal soil and their surface microscopic features(in Chinese).Chin Sci Bull,2016,61:1604-1611[周倩,章海波,周阳,等.滨海潮滩土壤中微塑料的分离及其表面微观特征.科学通报,2016,61:1604-1611]
8 Corcoran P L,Biesinger M C,Grifi M.Plastics and beaches:A degrading relationship.Mar Pollut Bull,2009,58:80-84
9 Brandon J,Goldstein M,Ohman M D.Long-term aging and degradation of microplastic particles:Comparing in situ oceanic and experimental weathering patterns.Mar Pollut Bull,2016,110:299-308
10 Fries E,Dekiff J H,Willmeyer J,et al.Identification of polymer types and additives in marine microplastic particles using pyrolysis-GC/MS and scanning electron microscopy.Environ Sci Process Impact,2013,15:1949-1956
11 Zhou Y.Adsorption and partition pharacteristics of oxytetracycline by the microplastics in coastal environments(in Chinese).Master Dissertation.Yantai:Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,2017[周阳.海岸环境中微塑料对土霉素的吸附分配特征研究.硕士学位论文.烟台:中国科学院烟台海岸带研究所,2017]
12 Liao C C.Method of preparation and application of erucylamide.Cereals Oils,1993,(3):47-50[廖常聪.芥酸酰胺制法及其应用.粮食与油脂,1993,(3):47-50]
13 Rani M,Shim W J,Han G M,et al.Qualitative analysis of additives in plastic marine debris and its new products.Arch Environ Contam Toxicol,2015,69:352-366
14 Ashton K,Holmes L,Turner A.Association of metals with plastic production pellets in the marine environment.Mar Pollut Bull,2010,60:2050-2055
15 Ogata Y,Takada H,Mizukawa K,et al.International Pellet Watch:Global monitoring of persistent organic pollutants(POPs)in coastal waters.1.Initial phase data on PCBs,DDTs,and HCHs.Mar Pollut Bull,2009,58:1437-1446
16 Fischer M,Scholz-Bo?ttcher B M.Simultaneous trace identification and quantification of common types of microplastics in environmental samples by pyrolysis-Gas Chromatography-Mass Spectrometry.Environ Sci Technol,2017,51:5052-5060
17 Reisser J,Shaw J,Hallegraeff G,et al.Millimeter-sized marine plastics:A new pelagic habitat for microorganisms and invertebrates.PLo S One,2014,9:e100289
18 Fotopoulou K N,Vakros J,Karapanagioti H K.Surface properties of marine microplastics that affect their interaction with pollutants and microbes.In:CIESM Workshop Monographs No.46.Albania,2014.55-60
19 Set?l?O,Fleming-Lehtinen V,Lehtiniemi M.Ingestion and transfer of microplastics in the planktonic food web.Environ Pollut,2014,185:77-83
20 Farrell P,Nelson K.Trophic level transfer of microplastic:Mytilus edulis(L.)to Carcinus maenas(L.).Environ Pollut,2013,177:1-3
21 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.Sci Total Environ,2014,493:656-661
22 Zhou Q,Zhang H B,Li Y,et al.Research progress on microplastics pollution and its ecological effects in the coastal environment(in Chinese).Chin Sci Bull,2015,60:3210-3220[周倩,章海波,李远,等.海岸环境中微塑料污染及其生态效应研究进展.科学通报,2015,60:3210-3220]
23 Tsuge S,Ohtani H,Watanabe C.Pyrolysis-GC/MS Data Book of Synthetic Polymers:Pyrograms,Thermograms and MS of Pyrolyzates.Amsterdam:Elsevier,2011