Microplastics Pollution Characteristics In Global Fish Meal And Economic Fishes From The Laizhou Bay,China

Microplastics have become a new global marine pollutant,defined as plastic particles with a size of < 5 mm.As early in 2004,Thompson coined the term "microplastics" to define small plastic particles.The microplastics pollution had been reported in almost all marine environment,especially in coastal areas.Because of their small size,microplastics were easily mistaken as food or inadvertently swallowed during ingestion.Previous studies had proved the widespread existence of microplastics in marine organisms.And microplastics might be transmitted to higher animals through the food chain,even threatened human health.Therefore,identifying the characteristics of microplastics pollution in marine economic animals could not only assess the ecological risks to marine organisms caused by microplastics,but also analyze their potential health risks.In this study,by detecting the microplastics pollution characteristics in economic fishes of the Northern Chinese typical sea areas and major fish meals around the world,we discussed the characteristics of microplastics ingestion by marine fishes and their potential harm to other organisms.And provided data support for risk assessment about microplastics pollution.Digesting biological samples by chemicals and filtering by filters was the common method of microplastics investigation in marine organisms.At present,the commonly used chemical digestion reagents were 10%KOH and 30%H2O2.However,H2O2 produced dense foams while digesting biological samples(high content of proteins and fats),and improper operations could easily lead to loss samples and reduce the recovery rate of microplastics.Due to high content of proteins and fats in fish intestines and fish meals,it was necessary to explore ways to reduce foaming.In this study,we tried to use defoamers(simethicone)to eliminate foams generated by digestion.The results showed that defoamers were able to eliminate foams.The height of foams in beakers was kept lower than 3 cm.And,meanwhile,defoamers were able to inhibit the occurrence of foams in a period of time(0.5 h).In addition,the experiment had optimized the digestion conditions of digesting fish meals used 10% KOH and 30% H2O2,shortened the digestion time to 6 h.As a large amount of dross could not be digested after fish meals digestion,which contained a large number of microplastic particles.The experiment uesd 600 mesh sieves to recover fish meal dross,and used for the extraction and identification of microplastics.The recovery rate of microplastics in fish meals increased to 150 ~ 230% than before.This study collected fish meals from ten major fish meal producing countries around the world,and discussed characteristics of microplastics pollution in fish meals from different regions.Using the separation method optimized in this study,we separated microplastics in soluble matter and residue of fish meals.Then quantitative and qualitative analysis were carried out.The result showed that microplastics pollution was widely detected in fish meal samples from ten countries.The average microplastics abundance of fish meals was 6.8 ± 1.6 items/g;the lowest abundance of microplastics was detected in fish meals from Mexico(1.9 items/g);the abundance of microplastics in fish meals from Myanmar was 19.4 items/g,which was the highest level of microplastics pollution.The microplastics abundance in Peruvian fish meals with the largest global output was 8.3 ± 1.9 items/g,which was moderate pollution level.The microplastics abundance in fish meals from China was 17.6 ± 2.7 items/g,and the microplastics pollution was relatively severe.It might be related to the fact that fish meals in China were mainly made from small miscellaneous fishes.In separated microplastics,fibers were the main shape type(96.1%);the most common size was 500 ~ 1000 ?m(25.1%).A total of 6 polymers were identified,with cellophane(CP),polypropylene(PP)and polyethylene teraphalate(PET)being the most common types.According to results of microplastics abundance in fish meals,the data could use to estimate the total content of microplastics in fish meals imported from different countries in China.To sum up,we can see that microplastics pollution was common in major fish meals around the world.The microplastics pollution in fish meals was relatively high in the Southeast Asia and China.It might be related to the high pollution level of raw materials and fish habitats.The results of this study would provide a scientific basis to ecological risk assessment of microplastics in offshore fishes,and supply a basis to assess the potential risks of microplastics in fish meals and control microplastics pollution sources in fish meals.In order to analysis the high microplastics pollution status in Chinese fish meals.The experiment took 13 species of economically fishes from the Laizhou Bay in North China as the investigation objects,and explored the characteristics of microplastics pollution in the body.Microplastics in intestinal tissues were extracted by digestion and filtration.The size and shape of microplastics were observed by a stereomicroscope.The polymer composition was identificated by a Fourier transform infrared microspectroscopy(?-FT-IR).The results showed that microplastics pollution was common in all of the fish species from the Laizhou Bay.The average microplastics abundance of fish intestinal tissues was 1.8 ± 1.1 items/individual,ranged from 0.3 to 3.8 items/individual in each specie.The lowest abundance of microplastics was detected in mackerel(Pneumatophorus japonicus)(0.3 ± 0.3 items/individual).The abundance of microplastics in dotted gizzard shad(Konosirus punctatus)was 3.8 ± 2.0 items/g,which was the highest abundance of microplastics.In separated microplastics,fibers were the main shape type(83.2%);types of microplastics composition included cellophane(CP),polypropylene(PP),polyethylene teraphalate(PET)and polyvinyl acetate(PVAc),and CP was the most common polymer type(56.8%).Comparing with other Sea areas,the microplastics pollution on fishes from the Laizhou Bay was similar.Microplastics pollution was related to the living habits of fishes,the bottom-fishes were more likely to swallow microplastics than the upper-fishes.In this study,the content of microplastics in small fish commonly used for fish meal process was relatively high,it might lead to a relatively high content of microplastics in Chinese fish meals.Shape and chemical compound types of microplastics in fishes from the Laizhou Bay were inconsistent with results in Chinese fish meals.This study would provide a scientific basis to ecological risk assessment of microplastics in offshore fishes,and supply a basis to trace the source of microplastics pollution in fish meals with marine fishing as the main raw materials.