Total HCHs' and total DDTs' levels in surface sediments (SS) ranged from 0.5 to 17.5 ng g 1 and from 0.9 to 33.1 ng g 1, averaged 6.0 and 8.2 ng g 1, respectively. Total HCHs' and total DDTs' levels in suspended articulate matters (SPM) varied from 6.2 to 14.8 ng g 1 with a mean value of 12.3 ng g 1 and were from 3.4 to 25.7 ng g 1 with an average of 16.4 ng g 1, respectively. Lindane is the main HCHs' source and continuing use in the Yangtze Delta areas of 'pure' g-HCH (lindane) rather than technical HCH (a mix of largely a- and some g-HCH). DDTs in SS are mainly accumulated in history. However, high DDT fractions in SPM are indicators of new input of typical dicofol type DDT from 2002 to 2004. It can be seen that most samples from the Yangtze estuary were in ranges where adverse biological effects are expected, either occasionally or frequently.

Road dust samples were collected from central Shanghai in winter (January) and summer (August), respectively. Sixteen polycyclic aromatic hydrocarbons (PAHs) in the United States Environmental Protection Agency (USEPA) prioritycontrolled list were determined by GC/MS. Total PAH (t-PAH) concentrations in winter samples ranged from 9176 to 32,573 ng g 1 with a mean value of 20,648 ng g 1, while they varied from 6875 to 27,766 ng g 1 in summer with an average of 14,098 ng g 1. Spatial variation showed that city park (CP) samples had the lowest t-PAH concentration, while industrial area (ID) and traffic area (TR) and commercial area (CO) were the most polluted, in both seasons. PAH homologues concentrations were getting higher with the more rings and higher molecular weight (HMW) in all areas. The study of effective factors showed that grain size was only a minor factor influencing the accumulation of PAHs, whereas total organic carbon (TOC) was found to be closely correlated with t-PAH concentration. Prevailing winds could directly affect on the spatial distribution of PAHs. Chemical source apportionment studies took the form of principal component analysis (PCA), followed by compositional analysis. It was demonstrated that road dust PAHs in central Shanghai mainly came from the mixing of traffic and coal combustion. The contribution percentages of pyrogenic and petrogenic sources were respectively 71.0% and 11.4% in winter, while they were, 64.9% and 14.1% in summer, respectively. Road dust PAHs in Shanghai city mostly came from local sources.

HCHs and DDTs in salt marsh plants taken from intertidal flats in the Yangtze estuary and coastal area in April and July 2002 were determined by GC-ECD. A significant seasonal effect was observed for HCHs and DDTs in sources and concentration levels in different sample types including above-ground tissues and roots as well as the whole plants and rhizospheric sediments. The results indicated that the concentration of t-HCH was higher in the above-ground tissues than in their roots in April; however, the partitioning of DDTs between contaminated sediments and the roots showed the higher concentrations of t-DDT in their roots. HCHs and DDTs concentration levels were higher in above-ground tissues than in roots in July. BCFs of HCHs and DDTs exhibited lower values with higher levels of contaminants in sediments, and higher values with lower levels in sediments.

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2–5.5 ng g 1 and averaged 3.5 ng g 1 in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g 1, with a mean of 34.5 ng g 1. In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g 1 and averaged 13.8 ng g 1, whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g 1 with a mean value of 5.9 ng g 1. The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.

The natural isotopic compositions and C/N elemental ratios of sedimentary organic matter were determined in the intertidal flat of the Yangtze Estuary. The results showed that the ratios of carbon and nitrogen stable isotopes were respectively 29.8& to 26.0& and 1.6&–5.5& in the flood season (July), while they were 27.3& to 25.6& and 1.7&-7.8& in the dry season (February), respectively. The d13C signatures were remarkably higher in July than in February, and gradually increased from the freshwater areas to the brackish areas. In contrast, there were relatively complex seasonal and spatial changes in stable nitrogen isotopes. It was also reflected that d15N and C/N compositions had been obviously modified by organic matter diagenesis and biological processing, and could not be used to trace the sources of organic matter at the study area. In addition, it was considered that the mixing inputs of terrigenous and marine materials generally dominated sedimentary organic matter in the intertidal flat. The contribution of terrigenous inputs to sedimentary organic matter was roughly estimated according to the mixing balance model of stable carbon isotopes.