珠江下游至伶仃洋水体中多环芳烃的相态分布和传输特征

Partitioning and transport of Polycyclic Aromatic Hydrocarbons in surface water from the downstream to Lingdingyang of Pearl River

为了研究河口水体中多环芳烃（PAHs）的相态分布、传输特征及其变化趋势,本文沿珠江下游至河口对表层水体PAHs进行采样分析。结果显示,16种优控PAHs的总浓度为（17.50-168.35）ng/L,平均83.40 ng/L,其中溶解相为（3.76-83.60）ng/L,颗粒相为（1.59-84.75）ng/L。PAHs浓度自下游至伶仃洋有波动降低的趋势,该趋势受陆源的持续输入、浮游植物的吸附吸收以及海水的稀释作用等因素的共同影响;PAHs组成及两相分配的变化主要受控于输入特征、悬浮颗粒物和黑碳吸附以及盐析效应等环境因子。荧蒽和芘的分配系数Kp自珠江下游至伶仃洋的逐渐下降也说明了海水的稀释显著降低了悬浮颗粒物对PAHs的吸附。另外,特征化合物比值沿程的变化不仅指示了PAHs在广州段水体中较长的停留时间,也说明了虎门河口存在持续的PAHs输入。利用主因子分析和多元线性回归的方法,指示出煤和木材燃烧以及机动车排放是该区域表层水体PAHs污染的最主要来源,约贡献了80%的PAHs输入。

In order to study the phase distribution, transport and variation of polycyclic aromatic hydrocarbons （ PAHs）, surface water samples were collected along the downstream to Lingdingyang of Pearl River. The total concentrations of 16 US EPA PAHs ranged from 17.50 ng/L to 168.35 ng/L with the average of 83.40 ng/L [ dissolved phase ： （3.76 - 83.60） ug/L, particle phase ： （ 1.59 - 84.75 ） ng/L]. The declining trend of PAHs concentrations was showed from the downstream to Lingdingyang under the influence of the terrestrial continuous inputs, phytoplank- ton adsorption and seawater dilution. Variations of PAHs composition and partitioning were controlled by input pathway, adsorption of suspended particulate matters （SPM） and black carbons and the salting out effect. The partition coefficients of Fluo and Py decreased gradually indicated that the water dilution affected the adsorption of SPM to PAHs. In addition, the trend of Fluo/（ Py ＋ Fluo） suggested the longer retention time of PAHs in downstream of Pearl River and the continuous inputs of PAHs in Humen estuary. The principal factor analysis indicated the coal and wood combustion and vehicle emissions were the major sources of PAHs in the surface water, which contributed almost 80% of PAHs input.