Accumulation Characteristics And Safety Evaluation Of Heavy Metals In Commercial Fishes From Dachen Island Sea Area

Fish is a high-quality protein source with high nutritional value.It is an important part of human dietary consumption,and its food safety has attracted a lot of attention.In recent years,the offshore marine environment has been polluted to varying degrees by heavy metals.Heavy metal pollution is one of the marine environmental pollution that is teratogenic and lethal to fish.Moreover,heavy metals are difficult to degrade,accumulate in fish,and transmit and magnify along the food chain（web）.Human consumption of these fish will even endanger human health and safety.Therefore,in order to ensure the safety of human consumption of fish and the healthy development of fisheries in the Dachen island sea area,it is very important to investigate the accumulation level and pollution degree of heavy metals in fish and the health risk assessment of heavy metals ingested by human consumption of fish.In this study,the main economic fish in the Dachen island sea area were selected as the research objects and the samples were pretreated by microwave digestion method.Inductively coupled plasma optical emission spectrometry（ICP-OES）was used to analyze heavy metals such as cadmium（Cd）,zinc（Zn）,copper（Cu）,lead（Pb）and chromium（Cr）,and atomic fluorescence spectrometry（AFS-3100）was used to determine heavy metals such as arsenic（As）and mercury（Hg）.The differences and distribution characteristics of seven heavy metals in different tissues and organs and among species were systematically and comprehensively analyzed.In addition,the effects of feeding habits and different habitats on the accumulation of heavy metals in different tissues and organs of fish were analyzed.Finally,single-factor pollution index（P_i）,comprehensive pollution index(P_{comprehensive}),daily tolerance dose（EDI）,non-carcinogenic risk（THQ）and carcinogenic risk（TR）were used to evaluate the pollution level,health risk and food safety of fish muscle tissue.The conclusion was as follows:（1）The contents of heavy metals in the edible muscle tissues of 19 species of economic fish caught in Dachen island sea area were all in line with the relevant fish heavy metal pollutant limit standards in China,and the accumulation ability of fish muscle tissues to different heavy metals had certain differences.The contents of heavy metals in different tissues and organs of fish were quite different,and the accumulation of heavy metals in gill and liver was higher than that in muscle tissue,and in most fish,the accumulation of Hg in muscle tissue was higher than that in the gill and liver,which showed that different tissues and organs have different conversion rates to heavy metals.（2）The accumulation ability of heavy metals was different in different tissues and organs with different feeding habits.The highest concentrations of Cu and Zn were found in the livers of fish feeding on nekton,and the lowest concentrations were found in the muscle tissues of fish feeding on plankton and benthos.As was widely accumulated in the liver of fish that feed on nekton,while only a small amount was accumulated in the muscle of fish that feed on benthic animals.Hg was widely accumulated in the gills of fish that feed on benthic animals,while only a small amount was accumulated in the muscles of fish that feed on plankton.Cd is widely accumulated in the liver of fish that feed on plankton,while only a small amount was accumulated in their muscles.Pb accumulates widely in the gills of fish that feed on plankton,and only in small amounts in the muscles of fish that feed on nekton.Total Cr was widely accumulated in the gills of fish that feed on nekton,while only a small amount was accumulated in the liver of fish that feed on plankton.（3）The accumulation ability of heavy metals in different tissues and organs in different habitats was also different.In the fish living in the bottom and near layer,the liver contains more Cu and Zn heavy metal elements,while in the fish living in the middle and upper layer,the muscle contains less Cu and Zn elements.In fish living on the bottom,As was mostly found in the liver and less in the muscle.For the distribution of Hg,the gills of fish living at the bottom were higher,but the gills of fish living in the middle and upper layers account for a small proportion.Cd was widely present in the liver of pelagic fish,but it was rarely present in the muscle of near-surface fish.A large amount of Pb was distributed in the gills of pelagic fish,while a small amount was found in the muscles of bottom fish.For the proportion of total Cr,the proportion in the liver of fish living in the middle and upper layers was very small,but it was widely distributed in their gills.The correlation between the heavy metal content in different tissues and organs of fish and the heavy metal content in sediments was significantly stronger than that in water,and the influence of heavy metals in surface sediments was greater than that in seawater.（4）The pollution status of seven heavy metals in muscle tissues of main economic fishes with different feeding habits in the Dachen island sea area was analyzed and evaluated by single factor pollution index method and comprehensive pollution index method.According to the single factor pollution index,Hg in muscle tissue of feeding fish of nekton was at moderate pollution level,Cu in different feeding fish was at non-pollution level,and other heavy metals were at micro-pollution level.According to the average value of comprehensive pollution index of fish with different feeding habits,the fish in the sea area were pollution-free and could be safely eaten,and the order of heavy metal pollution level was nekton feeding fish>benthos feeding fish>plankton feeding fish,which indicated that fish with a high trophic level had a stronger ability to accumulate heavy metals.（5）The daily intake of heavy metals was used to evaluate the edible safety of edible muscle tissues of main economic fishes in the Dachen island sea area,and it was found that the daily intake of heavy metals such as As,Cd,Cu,Zn,Pb and Cr was far below the maximum limit,while Hg exceeded the limit,which should be paid attention to before eating.The results showed that the content of single heavy metal in fish in Dachen island sea area did not exceed the standard,and the THQ value of non-carcinogenic risk was less than 1,which indicated that there was no obvious non-carcinogenic health risk caused by eating fish.The TTHQ of combined non-carcinogenic risk of multiple heavy metals was also less than 1,indicating that the non-carcinogenic risk of combined exposure of multiple heavy metals in fish muscle tissue was at an acceptable level,and long-term consumption of major economic fish in the sea area would not cause significant non-carcinogenic health risk to the human body.From the carcinogenic risk point of view,the TR values of As and Pb in fish in this sea area were acceptable,and there was no significant carcinogenic risk,while the TR values of Cd and total Cr in muscle tissue of most fish were slightly higher than the acceptable level,which may have a certain potential carcinogenic risk to human health.