本文研究了长江口表层沉积物中多环芳烃（PAHs）和重金属（As、Cd、Cr、Cu、Hg、Ni、Pb、Zn）的含量、来源和生态风险，探讨了沉积物间隙水DOM与多环芳烃菲及重金属砷之间的相互作用。结果表明，长江口表层沉积物∑PAHs的浓度范围为76.9-2936.8 ng g-1，与世界其它河口相比，属于中等偏下。长江口近岸和非近岸PAHs的含量和组成不同，其中崇明岛岸边∑PAHs的含量最高。近岸沉积物PAHs的组成以4-6环为主，非近岸以2-3环为主。长江口PAHs来源主要以燃烧为主，煤燃烧和汽车排放是近岸沉积物中PAHs的主要来源，而非近岸PAHs主要来源于石油泄漏、蒸发。长江口表层沉积物不存在严重的PAHs生态风险。长江口表层沉积物重金属（As、Cd、Cr、Cu、Hg、Ni、Pb、Zn）分析结果表明，长江口整体区域上，Ni、Cr和As有一定程度的富集，其它重金属不存在明显污染。除了Ni，其它7种重金属在近岸含量均高于河道和海域，且大部分重金属在南支近岸含量高于北支近岸。形态分析结果表明Cd、Pb和Zn生物可利用性高于其它重金属，在长江口沉积物中具有一定的生态风险。城市工业污水排放、航运污染及沉积物性质（Fe、Mn、Al、TOC、Clay 和 Silt含量）主导重金属在长江口近岸、河道和近海域的分布。潜在生态危害指数评价结果表明长江口重金属属于轻度生态危害。长江口近岸、河道和近海域沉积物间隙水DOM呈中性，主要以大分子量物质（>30KDa）为主，DOC浓度分别为57.96、20.04和33.16 mg L-1。光谱特性结果表明，长江口三个区域DOM是微生物源和陆源的混合来源，以微生物来源为主，成分主要为富里酸。近岸DOM腐殖化程度较低，而苯环结构化合物、类蛋白物质较高，芳香环取代基主要以羧基、羟基、羰基和酯类为主；河道DOM芳香化程度最高，芳香取代基主要以脂肪链化合物为主，苯环结构、富里酸物质含量较低，类蛋白峰、类腐殖峰光强较小；近海域DOM的类腐殖峰光强最大，腐殖化程度最高。长江口DOM与重金属As之间的相互作用结果表明，As3+和As5+离子可与长江口DOM中类蛋白物质和类腐殖酸物质相结合，与类蛋白物质结合能力大于类腐殖酸。其中，河道和近海域单位质量DOM与As3+结合容量相近，均高于近岸。而近岸单位质量DOM与As5+结合容量最大。长江口DOM可与As5+发生明显的还原作用，而对As3+氧化作用影响并不明显。长江口DOM与菲之间的相互作用结果表明，长江口间隙水DOM与菲的结合能力由大到小顺序是河道>近海域>近岸。长江口DOM与菲的结合常数值与DOM溶液的紫外参数（SUVA254）值成显著正相关，说明DOM芳香性结构是影响DOM与菲相互作用的关键因素；水体pH值对长江口DOM与菲之间的结合有较大影响，中性条件下DOM与菲的结合能力最强。

The assessment of polycyclic aromatic hydrocarbons (PAHs) and heavy metak contamination in the surface sediments from the Yangtze estuary were systematically conducted. The ∑PAHs in all sediments varied from 76.9 to 2936.8 ng g-1. Compared with other estuaries in the world, the PAHs levels in the Yangtze estuary are low to moderate. The ∑PAHs levels and composition varied obviously in different estuarine zones due to different sources. The highest ∑PAHs concentration was observed in the nearshore of Chongming island. The PAHs composition showed that 4-6 ring PAHs were mainly found in the nearshore areas, while 2-3 ring PAHs were for the farther shore zones. The PAHs in the Yangtze estuary were derived primarily from combustion sources. A mixture of petroleum combustion and biomass combustion mainly from coal combustion and vehicle emission was the main sources of PAHs from the nearshore areas, while the spill, volatilization of petroleum from shipping process and the shoreside discharge was important for PAHs in the farther shore areas. The result of potential ecotoxicological risk assessment based on the sediment quality guidelines indicated that low PAHs ecological risk in the Yangtze estuary. The concentrations and speciation of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in the sediments of the nearshore areas, river channel and coastal zones of Yangtze estuary, China, was systematically investigated. Cr, Ni and As were the most heavily contaminated in the most of samples of the Yangtze estuary. The concentrations of all heavy metals except Ni in the sediments of the nearshore areas were higher than those of the river channel and coastal zones. In the nearshore areas, the concentrations of most heavy metals except Hg in the sediments of the southern branch were higher than those of the northern branch. The speciation analysis suggested that Cd, Pb and Zn in all sediments showed higher bioavailability than the other heavy metals, and thus posed ecological risk. Principal component analysis (PCA) indicated that the discharge of unban and industrial sewage, shipping pollution and the properties of the sediments dominated the heavy metal distribution in the Yangtze estuary. The result of potential ecotoxicological risk assessment indicated that low heavy metals ecological risk in the Yangtze estuary.The basic properties，UV spectrometry, fluorescence characteristics of DOM from the pore water of the nearshore areas, river channel and coastal zones of Yangtze estuary were discussed. The interaction between DOM and As or phenanthrene was systematically investigated. The results showed that the DOM in pore water from the Yangtze estuary mainly consisted of high molecular weight matter (>30KDa). The concentrations of DOM (DOC) from the nearshore areas, river channel and coastal zones were 57.96, 20.04 and 33.16 mg L-1, respectively. The DOM in the Yangtze estuary were from the mix source of microbial source and terrestrial source. Werein, the microbial source was dominant. Fulvic acid was the main ingredient of DOM. In the nearshore areas, the humification degree of DOM was lower than that in the other areas, while the amount of compounds with benzene ring structure and protein-like materials was higher. The substituents of DOM at aromatic ring contained more carboxyl, hydroxyl, carbonyl and ester. In the river channel, the aromatic degree of DOM was higher than that in the other areas. The substituent of DOM at aromatic ring contained more aliphatic compounds. And there was lower content of compounds with benzene ring structure and fulvic acid. The fluorescence intensity of protein-like and humic-like of DOM from the river channel was lower than that from the other areas. In the coastal areas, the humification degree was higher than that in the nearshore areas and channel.As3+ and As5+ ions can combine with the protein-like and humic-like materials of DOM from the Yangtze estuary. The binding ability of protein-like-As (As3+ and As5+) was stronger than humic-like-As (As3+ and As5+). The binding capacity of As3+ with unit mass of DOM from the river channel was close to that from the coastal areas, which was higher than that from the nearshore areas. The binding capacity of As5+ with DOM from the nearshore areas was higher than that from the other areas. As5+ could be reduced by the DOM from the Yangtze estuary obviously, while the oxidization of As3+ by DOM was not obvious. The order of the binding constant (KDOC) of the DOM in three zones and phenanthrene was the nearshore>river channel>coastal areas. In Yangtze estuary, the KDOC of DOM and phenanthrene correlated to the SUV254 of DOM positively, which indicated that the aromatic structure of DOM was the key for combination of DOM with phenanthrene. The pH could obviously affect the combination capacity of DOM with phenanthrene. Higher KDOC of DOM and phenanthrene was observed at pH 7 than that at pH 4 and pH 11.