甲基硅氧烷对水生生物富集效应的研究

发布时间：2018-09-18 06:50

【摘要】：甲基硅氧烷(Methyl siloxane)作为一种人造有机硅化合物,有线型和环状两种结构(分别用Ln和Dn表示,n代表化合物中Si原子的个数),由于其独特的理化性质而被频繁应用于国民经济的各个领域并且在多种介质中都有检出。环境中被有机体吸收的污染物的量对于污染物的风险评估有着重要的作用,因此本研究采用低剂量环境相关浓度的实验室暴露,使整个吸收阶段甲基硅氧烷在水中浓度维持在相对稳定的范围,以鲤鱼(Cyprinus carpio)作为受试生物,在鱼缸中暴露32 d后转移到清水中再培养32 d,测定鲤鱼体内甲基硅氧烷的含量,通过速率常数形式的方程,研究不同类型甲基硅氧烷在鲤鱼体内的富集和清除规律。采集双台子河口区域水生生物样品,测定生物体内不同类型硅氧烷的浓度,采用稳定同位素法测定生物营养级,利用生物体内脂肪当量浓度与营养级之间的线性关系,分析甲基硅氧烷在水生生物中的营养级放大效应。本研究表明:(1)实验室暴露期间,在鲤鱼体内一共检测到5种甲种硅氧烷,分别为D4、D5、D6、D7和L10,其在鲤鱼体内的含量随时间变化明显,暴露阶段开始时增长较快,随后变得较为平缓,在清除阶段,鲤鱼体内甲基硅氧烷含量持续下降。利用速率常数形式的方程,得到鲤鱼对几种甲基硅氧烷的吸收和净化速率常数,其中D4的生物浓缩系数(BCF)最高,为6197.34 L/kg,说明D4具有明显的生物富集性。(2)野外样品中一共检测到9种甲基硅氧烷硅,D3-D7,L7-L10,通过物种间的捕食关系进行食物链的划分,分析了三条主要食物链中甲基硅氧烷的营养级放大情况,在浮游生物—毛蚶—扁玉螺—葛氏长臂虾食物链中,D5(R=0.88,p0.001)、D6(R=0.72,p0.01)、L7(R=0.83,p0.001)、L8(R=0.76,p=0.001)在生物体内的脂肪当量浓度与生物体的营养级之间存在显著的正相关关系,表明以上4种甲基硅氧烷在此食物链中存在营养级放大性。综上所述,结合生物浓缩系数与营养级放大系数,D4、D5、D6、L7、L8具有生物富集效应,其中D4可以通过生物体直接与环境接触而产生生物富集效应,而D5、D6、L7、L8则可以通过在食物链中营养级放大作用产生生物富集效应。
[Abstract]:Methyl siloxane (Methyl siloxane) is a synthetic organosilicon compound. Wired and cyclic structures (Ln and Dn respectively represent the number of Si atoms in the compound) are frequently used in various fields of the national economy due to their unique physical and chemical properties and are detected in various media. The amount of pollutants absorbed by organisms in the environment plays an important role in the risk assessment of pollutants. The concentration of methyl siloxane in water was kept in a relatively stable range during the whole absorption stage. Carp (Cyprinus carpio) was used as the tested organism, exposed to fish tank for 32 days, then transferred to water for 32 days to determine the content of methyl siloxane in carp. The enrichment and removal of different methylsiloxane in carp were studied by the equation of rate constant. The samples of aquatic organisms in Shuangtaizi estuary were collected, the concentrations of different types of siloxane in organisms were measured, the biotrophic grade was determined by stable isotope method, and the linear relationship between fat equivalent concentration and nutritional grade was used. The effect of methyl siloxane on nutrient level amplification in aquatic organisms was analyzed. The results showed that: (1) during laboratory exposure, five species of methylsiloxane were detected in carp, namely D _ 4, D _ 5, D _ (6), D _ (7) and L _ (10). Their contents in carp changed obviously with time, and increased rapidly at the beginning of exposure stage, and then became more gentle. In the scavenging stage, the content of methyl siloxane in carp decreased continuously. The absorption and purification rate constants of several methylsiloxanes were obtained by using the equation in the form of rate constants, in which D4 had the highest bioconcentration coefficient (BCF). It was 6197.34 L / kg, which indicated that D4 had obvious bioenrichment. (2) nine species of methylsiloxane siloxane D3-D7 (L7-L10) were detected in field samples, and the food chain was divided by the predation relationship between species. The nutritional amplification of methyl siloxane in three main food chains was analyzed. There was a significant positive correlation between the fat equivalent concentration (FEC) and the nutritional level of organisms in the food chain of phytoplankton, Arca subcrenata, Arca platyphylla and prawns with long arms. D5 (RP0. 88) and D6 (R0. 72P0. 01) and L7 (R0. 83p0. 001) and L8 (RD0. 76mp0. 001) were found in the food chain of prawns, and there was a significant positive correlation between the concentration of fat equivalent in organisms and the nutritional level of organisms. The results showed that the above four methylsiloxanes had nutritional magnification in the food chain. In conclusion, the combination of bioconcentration factor and trophic grade magnification factor (D4D5D5D6D6, L7, L8) has bioenrichment effect, in which D4 can produce bioenrichment effect through direct contact with the environment. However, D5, D6, L7, L8 can produce bioenrichment by magnifying the nutritional grade in the food chain.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X17

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