【作者】 王伟；

【导师】 叶庆富； Jay Gan；

【作者基本信息】 浙江大学 ， 环境生物物理学， 2011， 博士

【摘要】 疏水性有机化合物,如多溴联苯醚、有机氯农药、拟除虫菊酯类农药等,普遍具有较大的辛醇/水分配系数(KOW),水溶性很低,疏水性很强,极易吸附和富集于环境中的土壤、沉积物、悬浮颗粒和生物体中,是目前环境中最主要的-类污染物。因此,开展疏水性有机物在土-水/沉积物体系中的环境行为与归趋研究有助于准确评价该类化合物的生态风险,为环境质量标准的制定提供理论依据。本论文以美国南加州地区索尔顿湖(Salton Sea)为区域模型,研究了疏水性有机物在水体沉积物中的污染水平和残留特征。研究结果发现索尔顿湖区域沉积物中有机氯农药的检出率为100%,总浓度最高可达109μg kg-1干重,平均浓度为6～30 ng g-1；拟除虫菊酯类农药的检出率为90%,总浓度可高达26 ng g-1。DDT及其降解产物DDE为该地区主要农药污染物,含量占农药污染总量的70%以上；联苯菊酯为主要的菊酯类农药,在所有好气沉积物样品占总菊酯类农药的90%以上,在90%的淹水样品中,占总菊酯类农药的50%以上。研究中结合地球统计分析软件ArcGIS和Surfer,采用Kriging(克里格)数学模型对浓度水平进行网格化(Griding)插值,建立了主要污染物的浓度水平等值线数字地图模型,直观地描绘了索尔顿湖的污染水平、浓度特征和空间分布规律。模型显示总体上该地区深层沉积物(5～30cm)较表层沉积物污染情况严重；阿拉莫河入湖口附近区域污染较新河入湖口附近严重；污染最严重的地方为河流入湖口附近15～30cm沉积物中,且以河流入湖口为中心沿四周浓度呈不断下降趋势,表明水体沉积物中DDTs的污染来源主要来于携带污染源的河水径流输入。土/沉积物-水分配系数Kd值和可溶性有机质亲和系数KDOC是评价疏水性有机物在环境中的迁移、扩散、富集等行为的重要参数。但是由于传统方法较难在不破坏系统平衡的条件下将可溶性有机质分离出来,因此目前关于很多疏水性有机物还没有真实Kd值及KDOC值的报道。本论文以热点疏水性有机污染物多溴联苯醚为代表,建立了多溴联苯醚在水体中自由态浓度的自动固相微萃取检测法,并将自动固相微萃取法结合传统液液萃取法,对传统吸附分配系数Kd值偏差进行校正。本研究结果发现传统LLE法可人为压缩PBDE的Kd值1.2～106倍。通过自动固相微萃取较正后得到BDE-28、47、66、99、100、153、154和183的天然沉积物有机碳标化分配系数log Koc分别为4.95～6.13、5.77～6.44、5.57～6.40、6.19～6.92、5.77～6.70、6.19～7.30、6.10～7.24和6.40～7.52；可溶性有机质吸附系数log KDOC值分别为5.81～6.81,5.48～6.19,6.05～6.78,5.10～6.31,6.08～6.99,6.43～7.24,6.35～7.20和6.60～8.02。总体上来说,PBDE在沉积物有机质和水体可溶性有机质中的吸附性都非常强,且PBDE的Koc和KDOc与其自身的正辛醇/水分配系数Kow之间呈显著正相关性。为了研究新型疏水性有机物——我国自主创制的新型除草剂丙酯草醚(ZJ0273)在环境中可能的行为与归趋,本研究将14C同位素示踪法与高效液相色谱系统分离纯化技术和LC-MSn等波谱分析技术相结合,对该除草剂在实验室淹水厌氧培养条件下的残留动态变化规律、矿化动力学和降解途径进行了研究。结果发现,培养100 d时,丙酯草醚在酸性红砂土(S1)、中性黄松土(S2)和弱碱性滨海盐土(S3)中,分别高达有26.5%、47.2%、和35.6%转化成为结合态残留。丙酯草醚不同位置芳环之间的矿化速度之间存在差异,A环的矿化速度显著快于B环和C环,总体上其在淹水胁迫下的矿化速度非常慢,100 d的总矿化量都不超过2.5%。丙酯草醚在S1、S2和S3中的母体半减期分别为：58～71 d,32～37 d和48～51天。本研究鉴定了丙酯草醚在淹水厌氧培养条件下的降解产物有：4-(2-(4,6-二甲氧基嘧啶-2-氧基)苄胺基)苯甲酸(M1)、4-(2-(4,6-二甲氧基嘧啶-2-氧基)苯甲酰)苯甲酸(M2)、2-(4,6-二甲氧基嘧啶-2-氧基)苯甲酸(M3)、2-(4-羟基-6-甲氧基嘧啶-2-氧基)苯甲酸(M4)和4,6-二甲氧基嘧啶-2-醇(M5)。初步推断出该除草剂在淹水厌氧培养下的降解途径主要有四条：a)丙酯草醚母体M通过酯水解反应脱去丙基生成M1,Ml氧化生成中间产物4-(2-(4,6-二甲氧基嘧啶-2-氧基)苯酰胺基)苯甲酸,由于4-(2-(4,6-二甲氧基嘧啶-2-氧基)苯酰胺基)苯甲酸非常不稳定,在淹水条件下迅速水解生成M2,M2进一步水解脱去对氨基苯甲酸生成M3,M3在微生物作用下可脱烷基生成M4,M4最终矿化开环,生成二氧化碳。b)丙酯草醚母体M通过酯水解反应脱去丙基生成M1,M1氧化生成中间产物4-(2-(4,6-二甲氧基嘧啶-2-氧基)苯酰胺基)苯甲酸,由于4-(2-(4,6-二甲氧基嘧啶-2-氧基)苯酰胺基)苯甲酸非常不稳定,在淹水条件下迅速水解生成M2,M2进一步水解脱去对氨基苯甲酸生成M3,M3在微生物作用下发生醚键断裂生成M5,M5最终矿化开环,生成二氧化碳。c)丙酯草醚母体M通过酯水解反应脱去丙基生成M1后,M1发生羧基化水解生成M3,M3在微生物作用下可脱烷基生成M4,M4最终矿化开环,生成二氧化碳。d)丙酯草醚母体M通过酯水解反应脱去丙基生成M1后,M1发生羧基化水解生成M3,M3发生醚键断裂后形成M5,M5最终矿化开环,生成二氧化碳。本论文进一步通过室外模拟农业生态系统实验探讨了丙酯草醚在土壤和油菜中的运转和残留。结果发现,丙酯草醚在土壤和植株中均不易运转,施药后120 d仍有90%以上的含量持留在土表10 cm以上,在油菜体内有95%以上的含量依然持留在标记叶中,籽粒、根和秸秆内的含量均低于1%。更多还原

【Abstract】 Hydrophobic organic compounds (HOCs), such as polybrominated diphenyl ethers, organochlorine pesticides, and pyrethroids, are a class of most widely detected organic contaminants in the environment. Due to their strong affinity for organic matter, HOCs tend to be absorbed by soil, sediment, solid particles and accumulated in biota. Therefore, a good understanding about their behaviors and fate in the environment will help us to make an accurate prediction for their risk assessment.Salton Sea in California, US, is an inland lake with elevated concentrations of agriculture-related chemicals in water and sediment since 1960s. For a better understanding about the eventual environmental fate of HOCs, in this paper, Salton Sea was selected as a study model to give a vast view about the occurrence and transport of organochlorine pesticides (OCPs) and pyrethroids. The results indicated notable existences of OCPs in sediments from Salton Sea with mean concentrations of 3-30 ng g-1 and the maximum concentration of 109 ng g-1. Derivatives/isomers of DDT (DF=100%) were the main OCPs and bifenthrin (DF=90%) appears to be the dominant pyrethroid. The pesticide pollution pattern was demonstrated by concentration-based-Kriging contour map model which was built based on geo-statistical analysis and traditional statistical analysis. From this model, significantly higher concentrations coulde be visually observed in samples from Alamo River than from New River, in air-exposed samples than in submerged samples and in surface sediment than in sub-surface sediments. To assess the potential risks to Salton Sea-dependent habitants, the concentration data for major contaminants was compared with sediment quality guidelines like effect-rang low (ERL) and threshold effect concentrations (TEC) and samples were frequently found with exceeding ERL/TEL for DDEs, DDTs and chlordane. The result hints that further safety assessment is necessary when constructing the species conservation habitat at Salton Sea. The partition coefficients Kd and KDOC are important parameters for predicting the environmental behaviors and fate of HOCs. However accurate determination of Kd and KDOC becomes increasingly difficult as Kow increases because HOCs with large log Kow undergo extensive sorption not only to particulate organic matter, but also to colloids such as dissolved organic carbon. In this study, the automated solid phase microextraction method was developed to get the freely dissolved concentration (Cw-SPME) and was further combined with the traditional liquid-liquid extraction to get the partition coefficient for main PBDEs in environment. Obvious underestimation of water sediment partition coefficient Kd values was observed when measured by LLE (Kd values were 1.2-106.3-fold underestimated comparing to SPME). The organic carbon normialized sorption coefficient log Koc were reported to be 4.95-6.13, 5.77-6.44,5.57-6.40,6.19-6.92,5.77-6.70,6.19-7.30,6.10-7.24 and 6.40-7.52 for BDE-28、47、66、99、100、153、154 and 183. The corresponding log KDOC were reported to be 5.81-6.81,5.48-6.19,6.05-6.78,5.10-6.31,6.08-6.99,6.43-7.24, 6.35-7.20 and 6.60-8.02. Great log KDOC values were derived from the SPME measurements, suggesting a strong tendency for PBDEs to complex with DOC. Results from this study showed that PBDE congeners have larger sorption coefficients than would be measured by the conventional method. The high affinity to DOC also means a potential for DOC-facilitated transport, thus extending the range of PBDE movement in environmental compartments such as surface streams.The degradation of a novel pyrimidynyloxybenzoic herbicide ZJ0273, (propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate) was studied in flasks simulating flooded field conditions using three representative field soils. The degradation half-life (T1/2) values were calculated to be 63.7,35.1 and 49.2 days for acidic, neutral and alkaline soils respectively. The metabolites of ZJ0273 formed during degradation were identified using various analytical techniques, viz., liquid scintillation counting (LSC), high performance liquid chromatography (HPLC) and liquid chromatography-mass spectroscopy (LC-MS/MS). Five metabolites were found and identified as 4-(2-(4,6-dimethoxypyrimidin-2-yloxy) benzylamino)benzoic acid (Ml),4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzamido)benzoic acid (M2), 2-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M3),2-(4-hydroxy-6-methoxy pyrimidin-2-yloxy)benzoic acid (M4) and 4,6-dimethoxypyrimidin-2-ol (M5). Two degradation pathways were concluded form the experimental data:a) The degradation of ZJ0273 was initiated by ester hydrolysis to form Ml, and then the phenyl ring (A ring) was cleaved from M1 to form M2, and then M2 was transformed to M3 through hydroxylation, after which M3 was demethylated to M4;b) The propyl group in the parent compound was broken to form M1 and then Ml was further carbonylated to M2. The M2 was degraded into M3, and then further cleaved into M5.c) The degradation of ZJ0273 was initiated by ester hydrolysis to form M1, and then the phenyl ring (A ring) was cleaved from M1 to form M3, which was further demethylated and form M4;d) The propyl group in the parent compound was broken to form M1 and then M1 was further carbonylated cleaved to form M3 and then further cleaved into M5.An ourdoor experiment was further conducted to simulate the transportation and residue of ZJ0273 in agro-ecosystem. The results showed that ZJ0273 has weak leaching ability in soils and about 90% of the induced amount was remained in the surface 0-10cm soil at 120 d after chemical treatment (DAT). ZJ0273 has weak transportation in the oil rape seeds and more than 95% of the induced amount was remain in the labeled leave at 120 DAT. Less than 1% was transported to the root, stem and seed in matured rape body, suggesting a low dietary exposure for humans.更多还原