Pollution Of Mercury And Microcystins In Aquaculture Fish Of Wujiang Reservoir And Its Possible Harm To Human

Objective: Investigating the cultured fish in Wujiang Reservoir,to know the pollution status of mercury,microcystins and the composition of fatty acids in the fish,and to explore the potential hazards that may be brought to humans after ingesting fish.Methods: 205 samples randomly were collected in Wujiang Reservoir.The THg was measured by cold vapor atomic fluorescence spectroscopy(CVAFS)after digestion by nitric acid.The MeHg was measured using GC-CVAFS method after digestion by alkaline solution.The MC content measured with high performance liquid chromatography(HPLC)after using solid phase extraction method.FAs was measured using national standard method of fatty acid determination(GB 5009.168-2016).Referencing to Water environmental health risk assessment model recommended by the US Environmental Protection Agency,the potential risk prediction of methyl mercury and microcystin in fish tissues was predicted.Results: In this study,205 samples were collected,with a total of 11 kinds of fish.1.The total mercury content ranged from 2.98 to 185.05ng/g,the average content was 22.88±22.79 ng/g.The total mercury content in bighead carp was significantly higher than that of other fish species in addition to outside of crucian carp(P<0.05).The content of methylmercury ranged from 0.16 to 49.09 ng/g with an average content of 6.02±6.62 ng/g.The content of methyl mercury in fish with a lot of total mercury content is also more.By feeding habits,.mercury concentration in carnivorous is obviously higher than herbivorous and omnivorous.And filter-feeding fish was obviously higher than herbivorous fish(P<0.05).2.The total lipid content of catfish was the highest(3.02 ± 0.54 g/100g),bighead carp was the lowest(0.76 ± 0.09 g/100g).There is no correlation between MeHg and total lipid content(r=0.101,P=0.077).The content of SFA and MUFA is higher in catfish and longsnout catfish,and the lowest in perch than others.The content of n-6PUFA in catfish and the longsnout catfish was highest.The lowest bighead carp.The content of n-3PUFA in catfish was highest,the lowest was grass carp.The statistical analysis of SFA,MUFA and n-6PUFA had a positive correlation with total lipid(r=0.882?0.955?0.818,P<0.05).There was no significant difference in the EPA+DHA of four species of fish(P>0.05).The content of EPA and DHA in winter and summer showed obvious seasonal differences in catfish(P<0.05).3.The water of Wujiang Reservoir was 0.07±0.05?g/L,lower than the national drinking water health standard(GB 5749-2006)recommended value 1.0?g/L.Microcystins were detected in all kinds of fish,and the detection rates of MC-RR and MC-LR were 53.6% and 51.7%,respectively.4.Under the condition of normal healthy adults(250mg)and cardiovascular disease(1000mg)patients every day required a minimum of EPA+DHA fish intake,and not exceeded the PTWI standard of MeHg in the recommended daily intake(0.23?g/(kg·d).Catfish daily consumption of 75.48 g can reach 250mgEPA+DHA per day,while grass carp needs 416.99 g,and the RNC calculated in this study is less than 1.Conclusions: 1.The total mercury and methylmercury contents in fish samples were lower than those in China's "food pollutant limit" standard(GB 2762-2017).2.The highest levels of LR and RR microcystins detected in fish samples were 0.08 g/g,and the detection rates were 51.7% and 53.6% respectively.3.Catfish,river group and silver carp are rich in high-quality unsaturated fatty acids,which can provide more EPA and DHA nutrients in Wujiang.4.The risk levels of microcystins and methyl mercury in fish samples were at the maximum acceptable risk level.