多环芳烃在珠江口的百年沉积记录

伶仃洋西滩为珠江口的重要沉积区之一.本文分析了采自伶仃洋西滩沉积钻孔(Core 25)中多环芳烃的垂直分布和含量特征,结合²¹⁰Pb定年,重现了该地区近百年来多环芳烃(PAH)的沉积历史.多环芳烃在整个沉积剖面(0～62cm)的含量介于59～330ng·g^-1 (干重) .从19世纪60年代开始,PAH沉积通量逐渐上升,在20世纪50年代达到第一个高峰值.PAH含量在20世纪60～70年代有所降低.20世纪80年代后,PAH含量急剧上升,并在90年代达到最高值.珠江口沉积柱中的多环芳烃主要为热成因来源,其通量变化与周边人类活动(国内生产总值,机动车数量,能源消耗)呈正相关.大气干湿沉降及地表的冲刷作用是PAH进入水体沉积物的主要途径.

Over One Hundred Year Sedimentary Record of Polycyclic Aromatic Hydrocarbons in the Pearl River Estuary, South China

The western shoal of the Lingding Bay is known to be an important deposition zone of terrestrial substance in the Pearl River Estuary (PRE). In this study, the vertical variations of concentration and fluxes of polycyclic aromatic hydrocarbon (PAH) are investigated in a core from the west shoal of Lingding Bay. In combining with 210Pb-dating, the PAHs sedimentary record in the last 100 years is reconstructed. The sigmaPAH concentration ranged from 59 ng x g(-1) to 330 ng x g(-1) throughout the core with two distinct peaks. An initial increase in sigmaPAH concentration was found around the 1860s, followed with the first maximum in the 1950s. There was a decrease in total PAHs concentration and flux in 1960s and 1970s. A sharp increase in PAHs levels was observed from 1980s and a maximum was found in the 1990s. PAHs diagnostic ratios indicate that PAH in the sediment core are mainly of pyrolytic origin. PAHs concentrations are found to correlate positively with the Gross Domestic Production, vehicle numbers and power generation in the surrounding regions, indicating that the PAHs in the sediment core are mainly anthropogenic. Atmospheric deposition and land runoff may serve as the important pathway of PAHs input to the sediment.