Characteristics Of Antibiotics Contamination And Consumption Risk Of Seafood In Typical Culture Areas Of The Beibu Gulf

Antibiotics are widely used for bacterial disease prophylaxis and treatment in humans and animals and also as feed additives to promote growth in husbandry and aquaculture.Recently,the abuse of antibiotics is becoming more and more serious.Therefore,antibiotic residues in the environment had been paid much attention by scientists worldwide.As the last clean sea area of China,Beibu Gulf has always been the most suitable aquaculture bases because of its superior natural conditions.Following the rapid development of mariculture,large quantities of aquiculture wastewater were discharge into the Beibu Gulf,which aggravated the pollution of antibiotics in this area.However,the pollution of antibiotics in the Beibu Gulf has seldom been reported.In this study,19 antibiotics belonging to 4 groups,including 8 sulphonamides,5 fluoroquinolones,4 macrolides and 2 chloramphenicols were investigated.This study focuse on the occurrence,bioconcentration and human dietary exposure antibiotics from different farming models,biota,growth stages,feed and environmental matrices in typical mariculture farms,estuaries,and nearshore and offshore areas of the Beibu Gulf.Then the sources and behavior of antibiotic contamination in different breeding stages were investigated in Maowei Sea.This research will provide scientific basis for the prevention and control of antibiotic pollution in this area.Conclusions of this study are as follows:?1?The total concentrations of antibiotics in closed mariculture ponds,estuaries,nearshore areas and offshore area of the Beibu Gulf were about 43.2-885 ng L^-1,22.4-118 ng L^-1,22.7-24.5 ng L^-1 and 1.81-3.23 ng L^-1,respectively.Their concentrations decreased in turn,indicating that the mariculture ponds are important sources of antibiotic pollution on the coast of the Beibu Gulf.The total concentrations of antibiotics in the sediments of culture ponds?3.2-83.2 ng g-1?was also higher than that in the sediment of natural sea area?11.7-21.8 ng g-1?,which might be affected by water or feed residue.The above results showed that the content of antibiotics in water and sediment of culture ponds was higher than those in natural sea areas.Ten antibiotics were detected in feed samples with concentrations ranging from 0.03 to 95.4 ng g-1,demonstrating that the widely presence of antibiotics in the feed might be added directly or residual antibiotics in the raw material of the feed.?2?The total concentration ranged from 0.81 to 13856 ng L^-1 in the mariculture ponds of the Maowei Sea.Under the influence of typhoon and torrential rain,the disease broke out and the use of antibiotics,especially erythromycin,increased sharply.As a whole,the antibiotic contents in Qinjiang River were higher than that of aquaculture ponds when it was not affected by typhoon rainstorm,which suggested that the effect of Qinjiang River on antibiotic pollution in Mawei Sea was higher than that of the culture pond.For sediment,feed and biological samples,norfloxacin?NOX?was detected in all samples and quinolones accounted for more than 60%of the total antibiotics,indicating that quinolones are the main antibiotics in these samples.?3?The bioconcentration factors?BCFs?were used to analyzed the concentration of antibiotics in different organisms.The values of BCFs in Beibu Gulf and Maowei Sea were 0.55-10,774 L kg-1 and 5.0-11,226 L kg-1,respectively.The BCFs values of sulfamethoxazole,sulfadiazine and NOX were greater than 5000 L kg-1,showing that they are bioaccumulative.Therefore,the risks that antibiotics may pose to aquatic organisms cannot be overlooked.?4?The estimated daily intakes?EDIs?of antibiotics via aquatic products of the Beibu Gulf and Maowei Sea were 0-148.9 g d^-1 and 0-1306.8 g d^-1,respectively.Compared with the acceptable daily intakes?ADIs?and maximum residue limits?MRLs?regulated by food safety,these aquatic products?shrimp,crab and oyster?of the Beibu Gulf reached the standard of safe consumption and could not pose a health risk to humans.However,though NOX in tilapia of the Maowei Sea could not pose a health risk to humans,its content was higher than the safe use standard.Thus,the potential elevated risk to humans by antibiotics residue in Beibu Gulf can not be ignored.?5?By estimated the total amount of antibiotics in water,sediment,shrimp and feed of the culture pond in Maowei Sea,the results showed that only about 0.3%of the antibiotics were derived from the feed.And in the end,about 56.81-62.17%was discharged into the sea through the water,about 35.88?40.97%was accumulated in sediment particles and about 2%entered the shrimp muscle.