Microplastics And Heavy Metals Pollution Investigation Of Dominant Fish In Huangpu River Five Artificial Backbone Rivers In Shanghai

In recent years,with the rapid urbanization developing,the release of substantial amounts of industrial and agricultural effluent has resulted in varying degrees of pollution in the water ecosystem.When microplastics and heavy metals are present in aquatic ecosystem,they will not only directly poison aquatic organisms,but also indirectly threaten human health through food chain transmission.As an important part of the aquatic environment,fish is an important indicator for assessing the environment.At the same time,as an important part of human dietary structure,the food safety has been of great concern.Shanghai is one of the earliest urbanization cities in China,and the study of microplastic and heavy metal pollution in its river fish is well represented.This paper selected five dominant fish species in five artificial backbone rivers in Huangpu river in Shanghai.Coilia nasus,Hemiculter leucisculus,Carassius auratus,Pseudobrama simoni and Pelteobagrus nitidus as the research objects,gills and digestive tracts of five species of fish were analysed for microplastics by dissolution with 30%H₂O₂,and muscle tissue was analysed for heavy metals by dissolution with HNO₃,aiming at investigating the pollution characteristics of the dominant fish microplastics and heavy metals,and evaluating their consumption risks comprehensively,providing reference for the research of fish microplastics and heavy metals in urban artificial rivers.The main research results are as follows:（1）A total of 537 microplastics were detected from five dominant fish and 200samples,with an average detection rate of 83.00%.The highest detection rate in five fish species is Coilia nasus（92.50%）,and the lowest is Hemiculter leucisculus（72.50%）.The average abundance of microplastics in five fish species is 2.69±2.74items/individual.The highest abundance in five fish species is Pseudobrama simoni（2.95±3.22 items/individual）,and the lowest is Pelteobagrus nitidus（2.53±2.35items/individual）.According the living habits of fish,the detection rate and abundance showed fish living in middle-lower is greater than fish living in upper-middle and phytobenthivore fish is greater than omnivore and carnivore fish.The highest average detection rate and abundance of fish microplastics in the five rivers is Dazhi River（91.89%and 3.43±3.24 items/individual）,and the lowest is Longquan River（72.50%and 1.63±1.58 items/individual）.The abundance of fish microplastics in Dazhi River is significantly higher than that in Longquan River（P<0.05）.（2）368 and 169 microplastics were detected in the digestive tract and gill of 200fish,respectively.The detection rate and abundance of microplastics in the digestive tract are 70.50%and 1.84±2.31 items/individual,which are significantly higher than49.00%and 0.85±1.20 items/individual of gill（P<0.01）.After further analysis of 10samples of 5 species of fish,78 and 40 microplastics were detected in the digestive tract walls and contents of 50 samples.The detection rate and abundance of microplastics in digestive tract wall are 70.0%and 1.56±1.63 items/individual,which are significantly higher than 42.0%and 0.80±1.14 items/individual in content（P<0.01）.The microplastics in digestive tract wall of five fish species accounted for 66.07%of the total microplastics in the digestive tract.（3）The mainly proportion of microplastics shape is fiber（53.07%）and fragment（33.15%）;Fibrous microplastics are predominantly found in the gills and digestive tracts.The proportion of fibrous microplastics in gills is 59.76%,which is significantly higher than 49.73%in digestive tract（P<0.05）;The proportion of fragment microplastics in digestive tract is 35.87%,which is significantly higher than that 27.22%in gill（P<0.01）.The highest proportion of microplastics shape in the digestive tract wall is fragment（43.59%）,and the content is fiber（53.00%）.The highest proportion of microplastics color is black（41.90%）,red（25.33%）and blue（15.27%）are higher.The mainly proportion of microplastics color in the digestive tract is black（43.48%）and red（27.99%）,the gill is black（38.46%）and blue（25.44%）,the digestive tract wall is black（43.59%）and the content is red（45.00%）.The highest proportion of microplastics size is≤1mm（83.80%）.The microplastics at different parts in the fish are mainly≤1mm in particle size,84.78%in digestive tract,81.66%in gill,82.05%in digestive tract wall and 95.00%in content.Microplastics size>2mm weren’t detected in the content.A total of 95 microplastics and 12 different polymer types were detected by Fourier micro-infrared spectroscopy.The main three types are cellophane（40.96%）,polyethylene terephthalate（20.48%）and ethylene-vinyl acetate copolymer（12.05%）.（4）The proportion of samples with Zn content exceeding the standard（>50mg/kg）in Carassius auratus,Pseudobrama simoni and Pelteobagrus nitidus,excess rate is3.50%,and other four content of heavy metals isn’t exceed the standard.According to the monomial pollution index and comprehensive pollution index,Zn and Cr are the main pollution elements in fish muscle in artificial backbone rivers in Huangpu river in Shanghai.Pelteobagrus nitidus and Carassius auratus are the main polluted fish species.The target hazard quotient（THQ）in five fish species is less than 0.2,and the total target hazard quotient（HI）is less than 0.02,both of which are less than 1,the cancer risk（CR）level is very low risk.According to the number of THQ、HI and CR,indicating that eat the five fish species in five rivers is relatively safe.There is not the certain health risk of heavy metals for eating some fish in five artificial backbone rivers in Huangpu River in Shanghai.The results of this study showed that the detection rate and abundance of fish microplastics in five artificial backbone rivers in Huangpu River in Shanghai were slightly higher than those in its natural waters,and the overall level is low,and the dominant microplastic types differed significantly,with residential household products and agricultural film waste probably being important sources.The presence of light contamination of Cr and Zn in fish muscle is not a health risk for consumption,and the level of heavy metal contamination is low.