长江武汉段不同粒径沉积物中多环芳烃（PAHs）分布特征

将采自长江武汉段的沉积物湿筛分成5个粒径的组分（>200 μm，200～125 μm，125～63 μm，63～25 μm，<25 μm），分别测定其中多环芳烃(PAHs)的含量.结果表明，不同粒径沉积物中PAHs组成基本相同，均以3环以上PAHs为主，但是∑PAHs浓度相差很大，范围为26.1～7 135.9　ng/g.其中，>200　μm沉积物中∑PAHs浓度最高，为7 135.9 ng/g；63～25　μm沉积物中∑PAHs浓度最低，为26.1　ng/g.占沉积物38.6%质量分数的<25　μm沉积物富集了沉积物中约75%的∑PAHs.总有机碳是影响PAHs在不同粒径沉积物中分布的主要因素，不同粒径沉积物中PAHs与总有机碳呈显著正相关（p<0.01）.此外，有机质类型、结构也是影响PAHs在不同粒径沉积物中分布的重要因素.

Study on the Grain-Size Distribution of Polycyclic Aromatic Hydrocarbons in Yangtze River Sediment

Sediments collected from Yangtze River were separated into five size fractions ( > 200 microm, 200 - 125 microm, 125 - 63 microm, 63 - 25 microm, <25 microm) by wet sieving. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) listed as U.S. EPA priority pollutants were determined in the fractionated sediments. Sigma PAHs concentrations ranged from 26.1 to 7135.9 ng/g and varied largely among the different size fractions. The highest Sigma PAHs concentration (7135.9 ng/g) was associated with the largest size fraction ( > 200 microm) while the fine silt fraction (63 - 25 microm) contained the lowest Sigma PAHs concentration, 26.1 ng/g. Although the PAHs concentrations difference among different fractions was great, the composition of PAHs in the five size fractions showed similar pattern dominated by PAHs with three or more rings. Sediment particles less than 25 microm contributed 75% of the Sigma PAHs, while comprising 38.6% of bulk sediment dry weight. A significant positive correlation (p < 0.01) between PAHs and total organic carbon (TOC) existing for all size fractions demonstrated that TOC was important for PAHs distribution in sediments. Additionally, sediment organic matter type and structure also played an important role in PAHs distribution in different grain size fractions.