多环芳烃在珠江口表层水体中的分布与分配

Distribution and Partition of Polycyclic Aromatic Hydrocarbons in Surface Water from the Pearl River Estuary

为了解河口海岸带水体中多环芳烃（PAHs）的时空分布及其在水体及颗粒相中的分配及其控制因素,于2003年4月（春季）和2002年7月（夏季）采集了珠江河口及近海表层水体,采用GC-MS分析了水体中PAHs，结果表明,珠江河口及近海表层水体中多环芳烃浓度春季（颗粒相：4.0～39.1 ng/L;溶解相：15.9～182.4 ng/L）高于夏季（颗粒相：2.6～26.6 ng/L,溶解相：13.0～28.3 ng/L）。河流径流、悬浮颗粒物含量及光降解程度是控制水体PAHs浓度的主要因素，水体中以3环PAHs为主,伶仃洋内样品比珠江口外样品相对富集5,6环PAHs,夏季样品较春季样品相对富集3环PAHs,颗粒物的来源和组成是造成这种差别的主要原因，PAHs在颗粒相及水相中的分配系数（Kp）随颗粒有机碳含量、水体盐度增加而增加,随悬浮颗粒物含量增加而减少。有机碳归一化分配系数（lgKOC）与辛醇/水分配系数（lgKOW）间存在明显的线性关系,但高于线性自由能关系模拟值。

To obtain the temporal and spatial distribution and partition of PAH between water and particles in coastal area, water samples were collected from the Pearl River Estuary in July 2002 （summer） and April 2003 （spring） and polycyclic aromatic hydrocarbons （PAHs） were analysed with GC-MS in the present study. Total PAH concentrations in water samples were higher in spring （cp ： 4.0-39.1 ng/L;cw ： 15.9- 184.2 ng/L） than in summer （cp： 2.6-26.6 ng/L; cw ： 13.0-28.3 ng/L）. Suspended particle matter （SPM） content, photogradation and riverine discharge were the major factors controlling the PAH concentrations in water. The 3-ring PAHs were the dominant PAHs in water samples. The 5 and 6 ring PAHs are more enriched in the inner estuary samples than in outside estuary samples, and the 3 ring PAHs are more enriched in summer samples than in spring samples. The differences in composition and source of SPM might be responsible for this observation. The partition coefficient （ Kp ） increased with the particular organic carbon content of SPM and salinity of water and decreased with the SPM content of samples, which were consistent with the PAH partition theory. A linear correlation between lgKoc and lgKow were found in two sampling periods. The observed values of lgKoc exceed their predicted values calculated form linear free energy relationship between lgKoc and lgKow.