双壳贝类消化系统中微塑料的分离鉴定及应用研究

Separation and Identification of Microplastics in Digestive System of Bivalves

通过比较10%KOH和30%H_2O_2消解体系,建立了分离贝类消化系统中微塑料的前处理技术,采用傅里叶变换显微红外光谱仪(μ-FT-IR)和体式显微镜实现了微塑料的定性与定量分析,并用于检测栉孔扇贝和紫贻贝中的微塑料。结果表明,10%KOH消解体系的消解效率较高,聚丙烯(Polypropylene,PP)、聚乙烯(Polyethylene,PE)、聚苯乙烯(Polystyrene,PS)和聚氯乙烯(Polyvinyl chloride,PVC)加标回收率为96.7%~98.6%,方法精密度较好,相对标准偏差≤3.2%,能够满足检测要求。检测了青岛5个大型水产品市场采集的市售栉孔扇贝(50个)和紫贻贝(50个),以及野生紫贻贝(15个)中的微塑料,贝类中微塑料的个体检出率达80%以上,野生贝类中微塑料的个体检出率仅为40%。不同市区市售栉孔扇贝中微塑料平均丰度变化范围为5.2~19.4个/个体和3.2~7.1个/g(消化系统组织湿重),不同市区市售紫贻贝中微塑料平均丰度变化范围为1.9~9.6个/个体和2.0~12.8个/g,其中,市售紫贻贝中微塑料的平均丰度(1.9个/个体,3.17个/g)高于野生紫贻贝中微塑料的平均丰度(0.53个/个体,2.0个/g)。在贝类中分离到纤维、碎片和颗粒3种形状的微塑料,其中,纤维状微塑料的丰度最高且平均粒径最大。不同市区贝类消化系统中的微塑料随着粒径增大,数量呈递减的总体趋势,其中,小于500μm的微塑料占微塑料总量的26%~84%。贝类中丰度最高的微塑料的聚合物成分是赛璐玢(Cellophane,CP),其次是聚丙烯(Polypropylene,PP)。本方法具有简单、高效、对样品中微塑料损害低等优点,适用于海产品中微塑料的检测分析。

As a new type of pollutants,microplastics(small pieces of plastic with the longest dimension less than 5 mm)are bringing wide concerns by policy makers and researchers.The impact of microplastics on marine life is closely related to human health.Bivalves,as filter feeding creatures,can easily ingest microplastics in their feeding process.The microplastics in these bivalves can easily enter the human body through the food chain.In this study,a bivalve sample pretreatment method was established for separating the microplastics in their digestive system.Qualitative and quantitative analysis of microplastics was carried out by micro-Fourier transformed infrared spectroscope(μ-FT-IR)and Stereo microscope.By comparing the digestion systems of using 10%KOH and 30%H 2O 2,respectively,it was found that the digestion system using 10%KOH had better digestion efficiency.The recoveries of polypropylene(PP),polyethylene(PE),polystyrene(PS)and polyvinyl chloride(PVC)ranged from 96.7%to 98.6%,with RSD of less than 3.2%.Therefore,10%KOH was used to digest organic tissue for separating the microplastics from the bivalves'digestive system.With this digestion system,the microplastics in Chlamys farreri from local markets and Mytilus galloprovincialis from both local markets and wild environments in Qingdao were separated and analyzed.The results showed that microplastics were found in over 80%of the individuals purchased from the market and 40%in the collected wild individuals.The average abundance of microplastics in Chlamys farreri purchased from different markets varied from 5.2 to 19.4 items/individual and 3.2-7.1 items/g,while in Mytilus galloprovincialis,the numbers varied from 1.9 to 9.6 items/individual and 2.0-12.8 items/g.Farmed mussels contained more microplastics(average 1.9 items/individual,3.17 items/g)than wild mussels(average 0.53 items/individual,2.0 items/g).There were various colors of microplastics.The detected microplastics came from three shapes:fibers,fragments and granules.Fibrous microplastics,being the most dominant ones,accounted for 84.11%.The average size of fibrous microplastics(0.66±0.70 mm)was larger than that of the other two shapes of microplastics.The number of microplastics decreased with increasing microplastic sizes.Microplastics of less than 500μm coming from different markets were in the range of 26%to 84%.There was great spatial difference in the size of microplastics.The polymer composition of the microplastic was identified byμ-FT-IR.And it was found that the most common polymer component sin the samples were cellophane(CP),followed by polypropylene(PP).In the farmed mussels,PP was the most abundant component.The results showed that the abundance and types of microplastics in cultured or wild bivalves were closely related to their growing environment.