Transportation Characteristics And Risk Assessment Of Antibiotics In Vegetable Farmland Soil Amended Manure

The discovery and use of antibiotics has been a major advance in the history of human medicine.Antibiotics have been widely used in aqucuture to treat specific diseases therapeutically and sub therapeutically for increased feed efficiency or disease prevention,however,about 30-90% of antibiotics are not absorbed very well by the animal and are excrete in the urine or in manure,which resulted in a large amount of antibiotics residues in livestock manure.With the improvement of the quality of vegetables for the citizens,a large number of green vegetable production bases and organic production vegetable bases are emerging.Animal waste as organic fertilizers for agricultural,were continuously applied to farmland,which resulted in antibiotics becoming important pollutants in the soil.Antibiotics may be absorbed by soil which effected the quality of the soil.In addition,antibiotics may pollute surface water and groundwater through surface runoff and underground seepage,caused a series of environmental pollution problems.What's more,antibiotics can be absorbed by vegetables,which endanger human health through food chain.In this article,three tetracycline antibiotics(oxytetracycline,tetracycline,chlortetracy cline)were selected as our study objects.We have started pot experiment and field experiment by using the agricultural soil in Guangzhou.A sensitive analytical method was developed for determining tetracycline antibiotics in plants,water,soil and swine manure using HLB solid-phase extraction(SPE)and high performance liquid chromatography tandem mass spectrometry(HPLC-MS/MS).We investigated the distribution characteristics of antibiotics in the plant-soil-leaching water system after animal waste applied to farmland;We evaluated the health risks of tetracycline antibiotics in vegetables and the ecological risk of antibiotics in soil;At the same time,We used the loss of tetracycline antibiotics to estimate the antibiotic concentration in surface water and groundwater in Guangzhou city which resulted by animal wastes applied to agricultural soil.Then,we combined the distribution of species sensitivity and the risk quotient method to evaluated the ecological risk of antibiotics in water which resulted from animal wastes of containing antibiotics applied to farmland.The main conclusions of this paper are as follows:(1)Pot experiment and field experiment showed that three kinds of TCs could be detected in vegetable?soil and leaching water after animal wastes of containing antibiotics applied to farmland,and the transportation characteristics of tetracycline antibiotics in the Chinese cabbage-soil-leaching water system were generally similar,soil residual rate>water loss rate> Chinese cabbage enrichment rate.(2)The concentration of the three kinds of TCs in the stems and leaves of Chinese cabbage were 45.03 ?g/kg(OTC),10.59 ?g/kg(TC),and 22.52 ?g/kg(CTC),respectively.The health risk assessment showed that the amount of OTC,TC,and CTC ingested by the human through eating Chinese cabbage was 1.1 ?g,0.3 ?g,and 0.5 ?g,respectively,which was lower than the maximum limit of(10 ?g)tetracycline antibiotics limited by China's animal foods,which ingested by the human through eating meat,was also far lower the amount of allowable daily intake of the human the health(1800 ?g)limited by WHO.(3)The concentration of the three kinds of TCs in soil were 1013.68 ?g/kg(OTC)?174.08 ?g/kg(TC)? 313.11(CTC),respectively.In the early time of fertilization,the risk quotient of TCs in manure-amended vegetable farmland were between 1.36 and 44.33,it means has a higher risk to animal and plants in soil.With the increase of time from fertilization,the risk gradually decreases.In the end,the risk values of OTC,TC,and CTC were 0.42,0.28,and 0.42,respectively,which were at medium risk.(4)The concentration of OTC ?TC and CTC in surface water and groundwater in Guangzhou were17.17 ng/L and 2.09 ng/L(OTC)?6.02 ng/L and 1.36 ng/L(TC)?14.26ng/L,and 4.93 ng/L(CTC),respectively,which estimated by the loss rate of tetracycline antibiotics after animal manure applied to farmland.The human health risk quotient of tetracycline antibiotics were ranged from 6.8×10-8 to 3.9×10-5,both of which haven't exceed the maximum acceptable risk level recommended by the US EPA(10-4).The ecological risk values for the three TCs in surface water and groundwater ranged from 4.61 x 10-4 to 5.21 x 10-3,were far lower than 0.1,and were at low risk.