| Objective:By monitoring the pollution levels of ARGs and various antibiotics,heavy metals and some environmental factors in the surface water and sediment of the marine aquaculture environment in Zhoushan City,and analyzing the correlation between the contents of antibiotics,heavy metals and some environmental factors and ARGs pollution,revealing the pollution status of ARGs in the marine aquaculture environment of Zhoushan City and the influencing factors of the existence and spread of ARGs,to provide a reference for relevant environmental monitoring and risk assessment.Methods:In this study,33 and 28 samples were respectively collected from surface water and sediment of 3 mariculture areas（Dinghai,Zhujiajian,Liuheng）and the surrounding environment（control）in Zhoushan.The relative abundances of ARGs and an integron gene int I1 were detected by high-throughput q PCR.The concentrations of 15 antibiotics in the samples were measured by high performance liquid chromatography-mass spectrometry.In addition,the concentration of 6 kinds of heavy metals and 5 kinds of environmental factors in the samples were also determined.To elucidate the pollution characteristics and influencing factors of ARGs pollution in the marine aquaculture of Zhoushan,Redundancy analysis（RDA）and Spearman correlation analysis were used to analyze the relationship between target genes and antibiotics,heavy metals,some environmental factors,and the Kruskal-Wallis H test was used to analyze the difference in the distribution of target genes and antibiotics in different sampling points.Results:1、In the seawater and sediment samples,all the target genes were detected to varying degrees.sul1,sul2 and int I1 were the dominant detected genes.The detection rate and abundance of the quinolones,tetracyclines ARGs were relatively high,while the macrolide ARGs were the lowest.The relative abundance of target genes ranged from 10-5to 10-1,the average level of target genes detected in both sediments and seawater ranged from 10-3to 10-2,and there was no significant difference in the abundance of each target gene between sediment and seawater（P>0.05）.The average abundance of most genes in seawater and sediment samples of Dinghai and Zhujiajian was significantly higher than that in control samples（P<0.05）,The average detected abundance ranges of samples of Dinghai and Zhujiajian were 10-3-10-2and 10-3-10-1respectively,higher than that of Liuheng.The integron gene int I1 was significantly correlated with various ARGs（P<0.05）.2、Thirteen antibiotics were detected in seawater and sediment samples,and the detected concentrations in seawater and sediments ranged from ND～106.579 ng/L and ND～19.152 ng/g respectively.The detection rate of most sulfonamides（SAs）were100%,and the average concentration of sulfadiazine（SDZ）were the highest in the seawater and sediments samples,the detection rate and concentration of quinolone antibiotics and tetracycline antibiotics were also relatively high,while the macrolide antibiotics were relatively low.The concentration of most antibiotics had significant difference between the marineculture area and the control area（P<0.05）.Most antibiotics were significantly positively correlated with corresponding ARGs（P<0.05）,and also with non-corresponding ARGs（P<0.05）.3、The average detected concentrations of Ni,Cu,Zn,Cd,and Pb were respectively 0.582,2.513,18.758,0.056,and 0.245 ug/L in the seawater samples,and the order of average detected concentrations of heavy metals from high to low is Zn>Cu>Ni>Pb>Cd in seawater samples of Dinghai,Zhujiajian,Liuheng and control areas.There was no significant difference in the content of heavy metals in different sampling points（P>0.05）.The average detected concentrations of Ni,Cu,Zn,As,Pb,and Cr were respectively 17.322,20.665,68.121,7.904,23.280,and 17.755 mg/kg in the sediment samples,and the order of average detected concentrations of heavy metals from high to low is Zn>Pb>Cu>Cr>Ni>As in sediment samples of Dinghai,Zhujiajian,Liuheng and control areas,there was no significant difference in the content of heavy metals in different sampling points,except for the average concentration of Pb in different sampling points（P<0.05）.Ni,Zn,and Pb in seawater samples were significantly positively correlated with erm C,tet C,and qnr S,respectively（P<0.05）.4、Total phosphorus（TP）,total nitrogen（TN）,ammonia nitrogen（NH4+-N）,nitrite nitrogen（NO3-N）,chemical oxygen demand（COD）in seawater samples and total phosphorus（TP）,total nitrogen（TN）in sediment samples were detected ito varying degrees,and the distribution status of each environmental factor was different.Total nitrogen（TN）in seawater and TP in sediment were significantly positively correlated with multiple target genes（P<0.05）.Conclusion:1、ARGs pollution exists in the mariculture environment of Zhoushan,and it should not be underestimated.The pollution degree of resistance genes in water and sediment media is similar,the marineculture activity,marineculture pattern and human activity may be influencing factors of ARGs pollution,and integron gene int I1may play an important role in the spread and diffusion of ARGs in this region.2、Antibiotic pollution exists in mariculture environment in Zhoushan city,and mariculture may be an important source of antibiotic pollution.Antibiotics have direct screening effect on the distribution and existence of corresponding ARGs and indirect screening effect on non-corresponding ARGs.3、In addition to antibiotics,other physical and chemical indicators such as heavy metals and water quality parameters may also play an important role in ARGs pollution. |
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