【作者】 张学政；

【导师】 张增强； 李艳霞；

【作者基本信息】 西北农林科技大学 ， 环境工程， 2009， 硕士

【摘要】 随着集约化养殖的发展,抗生素类药物用量逐年增加,使抗生素的污染越来越严重。近年来不断有国内外文献报道,土壤、河流、海洋、地下水、污水处理厂出水甚至在自来水中检出抗生素类污染物。我国的兽药残留研究和监控工作起步较晚,抗生素对环境的污染在我国十分严重。与此同时,集约化养殖业的快速发展带来了大量畜禽粪便的排放。有机肥及其堆肥的农用,势必将会短期内大量增加土壤中的水溶性有机物(DOM)。而DOM是污染物在土壤中迁移的载体。这将影响到土壤中抗生素的吸附和迁移等环境行为,从而影响细菌抗药性的传播,影响到农产品的安全和人类的健康。因此,开展有机肥产生的DOM对土壤中抗生素环境行为影响的研究对于抗生素污染土壤的风险评价及修复和防止对地表与地下水体的污染及对食品安全都具有重要的意义。本研究旨在通过研究“外源”DOM对金霉素与土壤吸附的影响,为抗生素污染评价和防治提供理论依据,为畜粪及其堆肥的科学施用提供参考。本论文研究了不同条件下金霉素(CTC)的吸附动力学;以“序批式”试验,通过添加不同来源(牛粪、牛粪堆肥、猪粪、猪粪堆肥)、不同浓度(200 mg/L,50mg/L)水溶性有机物,研究对金霉素与土壤吸附的影响;通过透析法得到了不同分子量DOM,以序批式试验,通过添加不同分子量猪粪DOM,研究了大分子和小分子DOM对金霉素与土壤吸附的影响;并且通过添加不同浓度苹果酸和柠檬酸,研究不同种类和浓度小分子DOM对金霉素与土壤吸附的影响。主要结论如下:1. pH5.50,水/土比为500:1时,金霉素在土壤中的吸附符合“使液相中目标物浓度减少30~70%”的标准,且该条件下金霉素能够较快达到吸附平衡。2.水溶性有机物(DOM)对金霉素吸附影响的与DOM种类有关。当金霉素初始浓度较低时(﹤20 mg/L),200 mg/L不同种类DOM都明显抑制对金霉素与土壤的吸附。牛粪和牛粪堆肥DOM对金霉素吸附的抑制作用强于猪粪和猪粪堆肥DOM。说明,DOM对金霉素吸附的影响与其来源有关。3.整体来看,同浓度畜粪DOM与相应的堆肥DOM对金霉素与土壤吸附影响的差异不大,即畜粪堆肥化对于DOM对金霉素与土壤吸附影响的差异不大。但由于堆肥能明显较少畜粪中DOM含量,从而减弱DOM对金霉素与土壤的抑制,使液相中金霉素浓度相对减少,因此堆肥化可减轻畜粪施用造成的土壤溶液中金霉素浓度增大的危害。4. DOM浓度是影响金霉素吸附等温线的一个重要因素。与对照相比,50 mg/L DOM可使吸附系数Kf减小一半左右或更多;而与50 mg/L DOM相比,除猪粪堆肥DOM外,200 mg/L其它三种DOM都可使Kf明显减小。5. DOM对金霉素与土壤的吸附起抑制作用还是促进作用与金霉素初始浓度有关。当金霉素初始浓度较低时,不同种类DOM都具有抑制金霉素吸附的作用;而随着金霉素初始浓度的提高,DOM有促进金霉素吸附的趋势。DOM与金霉素结合,从而对土壤吸附金霉素有竞争效应可能是DOM抑制吸附的原因,而共吸附或累积吸附机制则可能是DOM促进金霉素吸附的原因。6.小分子DOM对金霉素吸附的抑制作用强于大分子DOM;小分子DOM的种类和浓度都是影响其抑制作用的因素,其中小分子的种类是更为关键的因素。更多还原

【Abstract】 With the rapid development of intensive culture, the use of antibiotic drugs is increasing year by year and the pollution of antibiotics is more and more serious. Recently, antibiotics occurrence in soil, river, sea, groundwater and effluent of wastewater treatment plant, even tap waters were reported in domestic and foreign literature. Research on veterinary drug residues and monitoring starts relatively late and antibiotics pollution to the environment is serious in China.Meanwhile, the rapid development of intensive culture cause a large emission of livestock manure. Agricultural applicability of organic manure and its compost will increase dissolved organic matter(DOM) in soil in a short term. The DOM is the carrier of pollutants transport in soil, which will influence the antibiotics environmental behaviors, such as sorption and transport and so on, which will influence the spread of bacteria drug-resistance, influence the safety of agricultural products and the health of people.So carrying out the research of effects of organic fertilizer on antibiotics environmental behaviors in soil is important for risk assessment on antibiotics pollution to soil, prevention and repair of antibiotics pollution to surface water and groundwater, and food safety. This paper aimed at effects of exotic DOM on sorption of antibiotics by soil, which will provide theoretical basis for assessment and control of antibiotic pollution, and provide reference for scientific application of livestock manure.This research studied sorption kinetics of chlortetracycline(CTC), a kind of tetracyclines antibiotics, sorption by soil in different conditions; with the method of batch experiment, effects of different source DOMs on sorption of chlortetracycline by soil were studied with adding DOMs from cow manure, cow manure compost, pig manure and pig manure compost and of different concentration(200 mg/L,50mg/L) by dialysis, DOMs of different molecular weight were obtained and with the method of batch experiment, the effects of different molecula weight DOMs on sorption of chlortetracycline by soil were studied by adding DOMs of low-molecular-weight and high-molecular-weight DOM from pig manure; And, the effects of different low-molecular-weight DOM on sorption of chlortetracycline by soil were studied by adding malic and citric. The main results are as follows:1. When pH was 5.50 and water/soil ratio was 500:1, chlortetracycline sorption by soil met the standard of“concentration of target compound decrease by the 30~70% range”, and under that condition, sorption equilibrium reached quickly.2. Effects of DOM on sorption of CTC by soil was related to the kind of DOM. When CTC was in low concentration(﹤20 mg/L), all of the different DOMs of 200 mg/L inhibited the sorption of CTC by soil significantly and the effects of DOMs from cow manure and cow manure compost were stronger than that of pig manure and pig manure compost. The result showed that the effect of DOMs on sorption of CTC by soil was related to the source of DOM3. On the whole, under the same DOM concentration, there were little difference of effects of DOMs from manure and its corresponding compost to CTC sorption by soil, namely composting had little effect on the influence of DOM to CTC sorption by soil. But as composting could reduce DOM concentration, which could reduce the inhibition effect of DOM on sorption of CTC by soil and reduce the concentration of CTC in liquid phase, thus composting could lighten the CTC concentration increment caused by manure application.4. The concentration of DOM was an important factor influencing sorption isotherm. Compared to the control treatment, 50 mg/L DOM could reduce adsorption coefficient Kf by about 50% or more; compared to the 50 mg/L DOM treatment, except the DOM from pig manure compost, the other 3 kinds of DOM with 200 mg/L, could reduce adsorption coefficient Kf significantly.5. The inhibition/promotion effects of DOM on sorption of CTC by soil were related to the initial concentration of CTC. When the initial concentration of CTC was low, all of the DOMs inhibited sorption, while when the initial concentration of CTC improved, the trend of promotion to sorption occured. DOM binding with CTC could cause a competition effect to soil sorption with CTC. This competition effect may be the reason for CTC sorption inhibition by DOM. While co-sorption or cumulative effects may be the reason for CTC sorption promotion by DOM.6. The inhibition effect of low-molecular-weight DOM on CTC sorption was stronger than that of high-molecular-weight DOM; the type and concentration of low-molecular-weight DOM were the factors influencing inhibition effect, so the type of low-molecular-weight DOM was the key factor of influencing inhibition of CTC by soil.更多还原