Distribution,Combined Pollution And Risk Assessment Of Antibiotics In Typical Mariculture Farms In Shandong Peninsula

In recent years,the occurrence of antibiotics in the environment has aroused widespread concern.Antibiotics are widely used in aquaculture as an antibacterial agent for the prevention and treatment of human and animal bacterial diseases.However,overuse of antibiotics may lead to the accumulation of antibiotics in cultured animals,threatening food safety and human health.In addition,when aquaculture wastewater is discharged into the natural water environment,antibiotics may may pose a potential risk to the ecosystem.The coasts of the Yellow Sea and the Bohai Sea of Shandong Peninsula are important mariculture areas in China,but there are few studies on antibiotics in these mariculture areas.In this study,17 kinds of antibiotics widely detected in the mariculture environment were selected as the target antibiotics,and the mariculture farms in Haiyang,Jimo along the coast of the Yellow Sea and Laizhou along the coast of the Bohai Sea were selected as sampling points.The temporal and spatial distribution of antibiotics in seawater,sediment/biofilm,organism and feed under different culture modes were explored.The contribution rate/quantity of each potential pollution source to the amount of antibiotics in natural water body was quantitatively described.The mechanism of combined pollution of heavy metals and antibiotics was analyzed.The ecological risks,resistance risks of antibiotics in water body and the health risks caused by human consumption of seafood were systematically evaluated.The main results were as follows:(1)The main antibiotic in the water from mariculture farms surrounding the Yellow Sea was trimethoprim,while those surrounding the Bohai Sea were trimethoprim and sulfamethoxazole.High concentrations of oxytetracycline and enrofloxacin were detected in the sediments from culture ponds surrounding the Yellow Sea,and the principal antibiotics in the sediments of the Bohai Sea were norfloxacin and enrofloxacin.Enrofloxacin and norfloxacin were also the chief antibiotics in organisms from mariculture farms surrounding the Yellow Sea and the Bohai Sea,respectively.The biofilm(mixture of manure from cultured organisms,microorganisms,feed and sediments)on the inner wall of greenhouse pond was more capable of accumulating antibiotics than the biofilm(mixture of sediments and microorganisms)attached to the culture cage and rope of shallow sea culture mode(raft culture,cage culture and bottom sowing culture),and other culture sediments.The level of antibiotics was the highest in greenhouse culture mode,and the lowest in industrial recirculating water culture.The antibiotic contents in water,sediments and cultured organisms in fish ponds were higher than those in sea cucumber ponds and mollusk ponds.(2)Principal component analysis-multiple linear regression(PCA-MLR)showed that the antibiotic burden of natural water bodies along the Yellow Sea and the Bohai Sea was principally from domestic sewage,with an average contribution rate of 87.3%and 63.3%to the total amount of antibiotics in the natural waters,respectively.The concentration of Zn was significantly correlated with the total antibiotic concentration and was proportional to several antibiotics in water and sediment(biofilm)samples in mariculture area of the Yellow Sea.In the natural water from the Laizhou Bay of the Bohai Sea,the concentration of Cu was positively correlated with several antibiotics.That might be related to the common source,the continuous input of Cu into the water and its participation in the competitive adsorption in the sediments,and easy complexation characteristic of the two pollutants.Some heavy metals(Mn,Zn,Cr)with high concentrations in aquaculture water and organisms were positively correlated with antibiotics in the Laizhou Bay,which might increase the selective stress of strains in aquaculture organisms.(3)Ciprofloxacin and enrofloxacin in water may present high ecological risks and resistance risks in mariculture water and natural water of the Yellow Sea,while the two antibiotics accumulated in fish may pose a considerable risk to human health through diet consumption.Fluoroquinolones posed medium to high ecological risks in natural water surrounding the Bohai Sea.Trimethoprim and enrofloxacin showed relatively high antibiotic resistance risks in natural water and mariculture water,which might exert selective pressure on the bacterial community in the water body,and even induce the generation of antibiotics resistance in aquaculture organisms.Consumption of turbots and sea cucumbers from mariculture farms of the Bohai Sea,which containing enrofloxacin might pose considerable risks to human body.All antibiotics detected in seafood were lower than the respective maximum residue limits.This study will provide scientific basis for the standardized use of antibiotics and the formulation of pollution control policies,and provide theoretical support for accelerating the green development of aquaculture and protecting the ecological environment of water areas.