Detection And Risk Evaluation Of Heavy Metals And Antibiotics In Tilapia Aquaculture Ponds In Guangxi Province

Since the 1980s,the industry and the agriculture of China are developing rapidly,but the rapid development of economic has brought about a series of environmental pollution,which has led to a sharp deterioration in the quality of commuting,especially in the farmland soil and aquaculture water.Heavy metals and antibiotics are two important environmental pollutants.The characteristics of multiple sources,lipophilicity,and non-degradability make heavy metals widely presented in the environment.Human activities such as industrial production and ore mining have caused serious problems with heavy metal pollution.Antibiotics have the efficacy of killing or inhibiting the growth of specific microorganisms,are stimulatory metabolites and their analogues obtained by the cultivation of microorganisms such as bacteria.Due to some reasons such as the frequent diseases,antibiotics are widely used,which causing them to remain in animal bodies and the environment,then causing serious problems such as product quality and safety,bacterial drug resistance and the like.The two pollutants will eventually be enriched through the food chain into the body of human,and endanger people's health.Therefore,the detection and evaluation of heavy metals and antibiotics in aquaculture environment is very important.In this study,nine typical freshwater aquaculture ponds in the main production area of tilapia in Guangxi Province were chosen as sampling sites for examining the distribution of in samples of sediment,water and fish tissue,and then evaluating the ecological risk in terms of enrichment.The major heavy metal pollutants and the main residual antibiotics are as follows:chromium,copper,zinc,cadmium,mercury,lead,arsenic,enrofloxacin(ENR),furaltazone metabolites(AMOZ),nitrofurantoin metabolites(AHD),nitrofurazone metabolites(SEM),furazolidone.Metabolites(AOZ),sulfadiazine(SDZ),sulfamethazine(SM2),chloramphenicol(CAP),oxytetracycline(OTC).At the same time,a long-term exposure experiment of copper and zinc aqueous phase was set up to study the related biological effects on tilapia.The following main conclusions have been obtained:1.Heavy metals detection and risk assessment in aquaculture ponds in tilapia production areas in Guangxi ProvinceThe results show that:(1)A11 these heavy metals were detected in all sediment samples,Hg,Pb and Cd were not detected in all water samples,and their content in sediment is higher than that in water samples.The remaining 6 kinds of heavy metals except As were detected in liver samples,but the detected contents of heavy metals in gill and muscle samples were lower,and the types were less.(2)The high content of Cr,Pb,As,Cu and Zn were detected in these sediment samples,but low for Cd and Hg.The order of the high content heavy metals in the sediment from the largest to the least is Zn,Cr,Pb,Cu,As.The order of heavy metals in the water from the largest to the least is Zn,As,Cu,Cr.The mainly accumulation regularity of heavy metals in fish tissues is:liver>gill>muscle.(3)Cd,Hg,Cu and Zn were detected in all liver samples,and the content order from the largest to the least is:Cu>Zn>Cd>Hg.Zn was detected in all gill samples,range from 7.020 mg/kg to 28.13 mg/kg.Cu wasn' t detected in all gill samples.Other heavy metals were detected in gill samples of several sampling areas,and their content were low.Only Hg and Zn in the muscle samples were detected,and the content of Hg was low,but far below the limited standard value of the edible parts of aquatic products in China and the EU,Korea and Hong Kong in China(0.5 mg/kg).That's to say,there was no excessive heavy metal in the edible part of tilapia,the tilapia is safe and reliable to eat.(4)Integrated pollution index value display is the sediments of ponds 1#,7#and 8#were contaminated with mild heavy metals,while the rest of the ponds were not contaminated by seven of common heavy metals.The four kinds of heavy metals that have been detected are not exceeding the standard in the nine culture ponds,and the comprehensive pollution index range of heavy metals in the water of nine culture ponds is 0.0334?0.0908,PI?1.0.2.Detection and Risk Assessment of Residue Antibiotics in Aquaculture Ponds of Main Tilapia Production Areas in Guangxi ProvinceThe results show that:(1)Among all the samples,only three kinds of antibiotics such as ENR,SM2 and OTC were detected.The content of AMOZ,AHD,SEM,AOZ,SDZ and CAP in all samples were all lower than the detection limits.(2)The residue antibiotics in sediment and water samples were ENR,SM2 and OTC,and the main residual antibiotics were ENR and OTC.The residual antibiotics in fish tissue samples were ENR and SM2.The content of ENR in sediment samples ranged from 1.24 ?g/kg to 19.35 ?g/kg,OTC ranging from 1.38?g/kg?38.01 ?g/kg,and the content of SM2 was 4.21 ?g/kg.The content of ENR in water samples ranged from 0.0147 ?g/L?0.0227 ?g/L,OTC ranging from 0.0327?3.242 ?g/L,and the content of SM2 was 0.0443 ?g/L.The content of ENR in liver samples ranged from 1.0567?6.323 ?g/kg.The content of ENR in muscle samples and SM2 in liver samples were 2.827 ?g/kg and 3.3 ?g/kg,respectively.(3)Pond 8#was seriously polluted by antibiotics.The contents of ENR,SM2 and OTC in sediment samples were as high as 19.35?g/kg,4.21 ?g/kg and 8.46 ?g/kg respectively.The levels of ENR and SM2 in liver samples were as high as 6.323 ?g/kg and 3.3 ?g/kg respectively.The residual amount of ENR in the muscle samples was 2.827 ?g/kg.OTC pollution in pond 5#was more serious,and OTC content in sediment was as high as 38.01?g/kg.The all detected residue antibiotics in sediment samples was much lower than that in sediments in oceans and rivers.ENR was trace detection in the muscle samples of pond 8#,and its content was much lower than the ENR residue limit standard(100 ?g/kg)in the edible part of aquatic products exported to Korea and Korea,but prohibited in the United States,Canada and Japan.In addition,the remaining eight antibiotics were not detected in muscle tissue,which is in line with the relevant provisions on food quality and safety in China,the European Union,the United States,Canada,Japan,Korea,Hong Kong,and other countries/regions.3.Biological Effects of Copper and Zinc Exposure to TilapiaThe results show that:(1)The proportion of Clostridium and Lactobacillus in the intestinal microflora of tilapia cultivated by heavy metals was reduced,and the corresponding heavy metal treatment led to a significant increase in the proportion of Firmicutes and deformable microbes.At the same time,the exposure of heavy metals also increased the content of unknown and unclassified microorganisms.(2)The Chaol,Shannon and ACE in Cu and Cu+Zn treatments were significantly different from those of the control group.The Chaol,Shannon,ACE and Simpson after heavy metal treatment were all higher than those of the control group,and the four index abundances of the combined heavy metal exposure treatment were the highest.(3)The intestinal microorganism and the alpha diversity index of the heavy metal exposure group showed that the heavy metal treatment would affect the alpha diversity index,and the higher the concentration,the greater the diversity index,the most significant effect of the 2.5mol/L Cu+ 25mol/L Zn composite exposure group on the intestinal microorganism.(4)The NMDS non metric multidimensional analysis based on the UniFrac distance showed that heavy metal exposure could make a great change in the species of intestinal microbes in the tilapia,and the higher the exposure concentration,the more obvious the clustering among individuals.