The levels and distribution patterns of the selected organochlorine pesticides (OCPs = p,p 0 -DDT, o,p 0 -DDT, p,p 0 -DDE, p,p 0 -DDD, a-, b-, c-and d-HCH) in surficial sediments from the Haihe River and Dagu Drainage River of Tianjin were investigated by means of gas chromatography coupled with micro-electronic capture detector (GC-lECD). Concentrations of OCPs in the sediments from the Haihe River ranged from 1.88 to 18.76 ng g À1 (mean 7.33 ng g À1 ) for P HCH, 0.32-80.18 ng g À1 (mean 15.94 ng g À1 ) for P DDT. Compared with the Haihe River, the Dagu Drainage River was much more contaminated by HCHs and DDTs, wherein P HCH ranged from 33.24 to 141.03 ng g À1 (mean 87.74 ng g À1 ) and P DDT ranged from 3.60 to 83.49 ng g À1 with a mean value of 35.52 ng g À1 . The concentration distribution of P DDT and P HCH was different indicated their different contamination sources. Composition analyses indicated that a recent usage or discharge of HCH and DDT into the Dagu Drainage River.

The concentrations of 13 currently used brominated flame retardants (BFRs) were analyzed in 16 sediment cores collected from the North American Great Lakes. Among them, 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE), decabromodiphenyl ethane (DBDPE), hexabromocyclododecane (HBCD), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), and hexachlorocyclopentadienyl dibromocyclooctane (HCDBCO) were more frequently detected than others. In general, these emerging BFRs have much lower concentrations than polybromodiphenyl ethers (PBDEs) and dechloranes. Inventories of the five BFRs named above, given on a logarithm basis, were found to decrease linearly with the increasing latitude of the sampling locations, but with weaker statistics than those previously reported for the dechloranes. Logarithm of surface fluxes, on the other hand, was found to be a better parameter in correlating with the longitude. With regard to time trends, the exponential increases in concentrations of these BFRs, particularly DBDPE and BTBPE, in recent years are particularly disturbing. The sediment concentration of DBDPE doubles every 3−5 years in Lake Michigan, and approximately every 7 years in Lake Ontario. The corresponding doubling times for BTBPE are about 5 and 7 years in Lakes Ontario and Michigan, respectively, although declines or leveling off were observed in the top sediment layers in Lake Ontario. In contrast to PCBs, PBDEs, and most dechloranes, the correlations between the surface concentration of emerging BFRs and the latitude or longitude of the sampling sites were not strengthened by normalization of the concentration based on the organic matter content of the sediment.