【作者】 王鑫宏；

【导师】 袁星；

【作者基本信息】 东北师范大学 ， 环境科学， 2010， 博士

【摘要】 邻苯二甲酸酯(PAEs)类化合物是目前环境中普遍存在的污染物之一,主要用作塑料增塑剂和农药载体,目前全球增塑剂市场的80%为酞酸酯类化合物。PAEs与塑料之间结合并不紧密,很容易脱离塑料本体进入环境,因此塑料制品的广泛使用导致环境中PAEs大量增加。研究发现,酞酸酯类化合物具有潜在的生物毒性,已被很多国家限制使用,美国国家环保局将其列为环境优先污染物,PAEs也被人们称为“第二个全球性PCB污染物”。环境中各种污染物并不是孤立存在的,大多数是多种污染物共存形成的复合污染,其中有机物与重金属复合污染是一类主要的污染类型。本文选取两种典型的酞酸酯类化合物邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)和重金属Pb为研究对象,考察实际环境条件下不同土地利用方式土壤中DBP/DEHP含量的年度变化;在实验室模拟条件下研究不同浓度DBP/DEHP单一及与Pb复合体系在土壤环境中的降解动态,同时考察污染体系对四种土壤酶(过氧化氢酶、转化酶、脲酶和磷酸酶)活性、微生物生物量碳和代谢熵的影响,以期为酞酸酯与铅复合污染对土壤微生态环境的影响及污染控制研究提供科学依据。研究结果如下:1.不同土地利用方式土壤中DBP/DEHP的年度变化(1)从年度(2007年4月至2008年4月)监测结果可以发现,大棚土壤中DBP(7.70-14.63 mg/kg)和DEHP(4.92-10.82 mg/kg)含量高于大田土壤DBP(2.23-7.31 mg/kg)和DEHP(3.34-9.53 mg/kg)的含量,其中DBP的差异更显著,表明DBP可能更容易从塑料本体脱离进入周围环境。(2)大田和大棚土壤DBP和DEHP的含量在4月至9月期间逐渐升高,其中大田土壤DBP/DEHP含量在9月份达到最大值,随后逐渐降低;大棚土壤DBP含量分别在9月和11月达到最大值,DEHP含量则分别在9月、11月和次年4月达到最大值,不同大棚土壤DBP和DEHP的含量变化存在差异,可能是由于不同大棚种植的农作物及施用农药种类不同而导致。2. DBP/DEHP单一及与Pb复合污染的生物降解(1)土壤中DBP/DEHP主要以生物降解为主,不同浓度DBP/DEHP的生物降解过程可用一级动力学方程来描述(R2均大于0.9),土壤中二者浓度越高半衰期越长;在实验浓度范围(10-1000mg/kg)内,DBP在土壤中的生物降解半衰期为4.38-15.1天,DEHP在土壤中的生物降解半衰期为11.09-26.56天,且相同浓度处理DBP的半衰期小于DEHP,表明DBP的生物降解性高于DEHP。(2)复合污染体系中,Pb(300mg/kg)对DBP/DEHP在土壤中的生物降解有抑制作用,其中DBP的生物降解性高于DEHP;Pb胁迫下DBP/DEHP在土壤中的生物降解动态仍可用一级动力学方程描述(R2均大于0.9),与同浓度(10-500mg/kg)DBP/DEHP单一污染处理相比,Pb胁迫下DBP/DEHP生物降解半衰期显著延长,分别为6.19-19.21天和16.82-47.48天。3. DBP/DEHP单一及与Pb复合污染对土壤微生物生物量碳(Cmic)和代谢熵(qCO2)的影响(1)不同浓度DBP/DEHP处理,土壤Cmic呈现降低-升高-降低-恢复稳定的趋势;相同浓度(100mg/kg)的DBP/DEHP处理,其土壤Cmic的峰值响应不同,DBP处理组的峰值(148.53mg C/kg)出现在培养第6天,DEHP处理组的峰值(110.54 mg C/kg)出现在培养第15天,且相应的DBP处理土壤的qCO2低于DEHP,说明DBP比DEHP更容易被土壤微生物利用,DBP的碳源利用率高于DEHP。(2)DBP/DEHP与Pb(300mg/kg)复合污染对土壤微生物的影响并非简单相加作用,在培养初期(25-35天)DBP/DEHP与Pb交互作用对土壤微生物生物量碳的影响多小于两者单独作用之和,随着培养时间延长(从培养第35天开始至培养结束),交互作用逐渐高于单独作用之和,但DBP/DEHP的浓度变化对交互作用影响不显著。随培养时间的变化Pb对交互作用的影响不同,可能的原因是培养初期微生物将其作为微量元素加以利用,培养后期Pb与DBP/DEHP及其中间降解产物形成了毒性更高的复合体。4. DBP/DEHP单一及与Pb复合污染对土壤酶活性的影响(1) DBP/DEHP对土壤过氧化氢酶和磷酸酶主要表现为激活效应;DBP/DEHP对土壤转化酶的影响不同,DEHP对转化酶以抑制作用为主,DBP在低浓度(10-100mg/kg)时对转化酶有抑制作用,高浓度(500-1000mg/kg)时刺激了转化酶活性;DBP/DEHP对脲酶均表现为抑制作用。从培养第25-35天开始,各处理土壤酶活性有逐步恢复且趋于稳定的趋势。(2)对比DBP/DEHP单一及与Pb复合污染对土壤酶活性的作用可以发现,在复合污染体系中,各处理土壤酶活性从培养第42天开始逐渐表现出趋于稳定的趋势,即Pb的加入使复合处理体系土壤酶活性恢复并趋于稳定的时间有所延长。(3)与土壤微生物生物量碳和代谢熵相比,DBP/DEHP的浓度变化对土壤酶活性的影响更显著。更多还原

【Abstract】 Phthalate esters (PAEs) compounds are prevalent in the current environment. They are mainly used for plastic plasticizers. In the global plasticizer market, 80% were the phthalate esters. PAEs are not chemical bonded with the PVC resins, which would bring about pollutions for water or soil. Numerous studies found that phthalate esters had potential biological toxicity. In many countries, the use of PAEs was restricted. The U.S. National Environmental Protection Agency lists them as environmental priority pollutants, PAEs have also been known as“the second global PCB pollutants”.A variety of pollutants in the environment was not exist alone. Most of pollutants are coexistent, including organic and heavy metal pollution. In this work, the concentrations of DBP and DEHP in farmland and greenhouse soil were monitored,DBP and DEHP were chose to study their degradation and impact in soil biochemical indicators (microbial biomass, metabolic quotients, catalase, invertase, urease and phosphatase). Their combined pollutions with Pb on these indicators were also studied. The findings are as follows:1. The concentrations of DBP and DEHP in soil were determined.(1) The same plastic greenhouses and field soil were selected to determine the concentrations of DBP and DEHP in the whole year. The concentrations of DBP (7.70-14.63 mg/kg) and DEHP (4.92-10.82 mg/kg) in field soil were lower than in greenhouses (2.23-7.31 mg/kg for DBP,3.34-9.53 mg/kg for DEHP). The results showed that DBP may be more easily from the plastic out into the surrounding environment.(2) DBP and DEHP contents were increased gradually from April to September in both greenhouses and farmland soils. The concentrations of DBP and DEHP in field soils reached the maximum and reduced later. The DBP in the greenhouse soil reached the maximum in September and November. The content of DEHP reached the maximum in September, November and April of the following year.2. Biodegradation of DBP and DEHP in the case of single and complex pollutions with Pb in soil(1) DBP/DEHP in soil were degradated mainly through biodegradation. Different concentrations of DBP/DEHP biodegradation processes could be described by pseudo first order reaction (R2 > 0.9). The higher DBP/DEHP concentration in soil, the longer half-life was. In the experimental concentration range, the half-life of DBP biodegradation in soil were 4.38-15.1 days, DEHP were 11.09-26.56 days. The half-life of DBP was less than DEHP in the same concentration, indicating that the biodegradability of DBP was better than DEHP.(2) Pb could inhibit the biodegradation of DBP/DEHP in soil. Biodegradation of DBP in the complex system was still higher than DEHP. When Pb was added, the biodegradation of DBP/DEHP could be also described by pseudo first order reaction (R2 > 0.9). The half-life of DBP/DEHP increased with the increasing initial concentrations. Compared with the same concentration of DBP/DEHP in single treatment, the half-life of DBP/DEHP biodegradation in complex pollutions was significantly longer (extended to 6.19-19.21 and 16.82-47.48 days, respectively).3. The effect of DBP/DEHP on soil microbial biomass carbon (Cmic) and metabolic quotient (qCO2) in single and complex pollution with Pb(1) The changement of microbial biomass carbon was lower-higher-lower-restore stability. The highest value of Cmic in DBP (148.53mg C/kg) treated soil was higher than DEHP (110.54 mg C/kg). The value of qCO2 in DBP treated soil was lower than DEHP. This result showed that the carbon utilization ratio of DEHP was lower than that of DBP.(2) The impact of DBP/DEHP in complex pollution with Pb on soil microbes was not a simple additive effect. In the prophase (25-35 days), the interaction of DBP and Pb on the microbial biomass carbon were smaller than the DBP and Pb alone. In the later experiment, (from 35 days to the end), the interaction gradually higher than the sum of DBP and Pb single. No significant difference was found in the different concentrations of DBP/DEHP and Pb complex treatments on the interaction of soil microbial biomass C.4. The influence of DBP/DEHP on soil enzyme activities in single and complex pollution with Pb(1) The activities of catalase and phosphatase were mainly by DBP/DEHP. The effects of DBP/DEHP on soil invertase were different. The activity of invertase were mainly inhibited by DEHP. DBP inhibited the activity of invertase at low concentrations (10-100mg/kg) and stimulated it at high concentrations (500-1000mg/kg). The activity of urease were inhibited by DBP/DEHP. From 25-35 days, the soil enzyme activities gradually restored and tended to stability.Cultured for 25-35 days from the start, the soil gradually restored the enzyme activity and tend to a stable trend.(2) Compared DBP/DEHP single and compound pollution could found that in the compound pollution soil, the activities of soil enzymes began to show a stable trend from the 42th day, i.e. the introduce of Pb prolonged the trend of soil enzyme activities restoring to stability.(3) Compared with microbial biomass carbon and metabolic quotient, the soil enzyme were nobatly influenced by the changement of DBP/DEHP concentrations in soil.更多还原