Modification of polymers by ion irradiation improves their effective charge density due to the generation of electron-donating groups.

No abstract

Spatial distribution, composition and possible source of 10 parent polycyclic aromatic hydrocarbons (PAHs) in littoral surface sediments from the Yellow Sea were investigated. The total PAHs concentrations varied from 12.4 to 8294.0 mug/kg dry weights, and the sites with the highest levels were all located in Dalian Bay. At most sampling sites, PAH components with moderate and high molecular weights were dominant, while percentage of low molecular weight species was higher at a few sites close to several harbor cities. The specific ratios of paired PAH isomeric compounds for source apportionment suggested that various pyrolytic procedures were the major origin in the Yellow Sea, whereas petrogenic cause only occurred at a small number of the monitoring sites. The averaged effect rang low (ERL) quotient for the studied PAH components was generally below the threshold value of 1.0 in most sea areas, indicated that the potential ecological risks of PAHs contamination in surface sediments were normally not high in the Yellow Sea, however, the situation in Dalian Bay should be cautioned due to the high mean ERL quotient.

A baseline survey of trace metals and organic pollutants in bivalves from the coastal areas of the Yellow Sea (China) showed the the concentrations of Cd and Pb in the bivalves from more than 85 and 73%, respectively, of the total sites (30 sites in all) exceeded the low limits of the national quality standards for marine organisms. At three sites, the contents of Cd in three species were even higher than the median limit, and a similar case with Pb occurred at another site. The tissue concentrations of As at four sites and of Hg at one site were above the low and the median limits, respectively, of the quality standards. At 43% of all sites, the levels of petroleum hydrocarbons were higher than the low limit of the quality standards, and the tissue concentrations at two sites even went beyond the median limit at one site and the high limit at the other. The concentrations of phthalate esters and polycyclic aromatic hydrocarbons (PAHs) in the collected bivalves were not high, as shown by peak values of 305 and 302 ng/g, respectively. The contents of polychlorinated biphenyls for all the species were much lower than the low limit of the quality standards. The compositional properties and isomeric ratios of PAHs indicated various pyrolytic procedures as the dominant origins. The sites with higher tissue contents of DDT and its metabolites (DDTs) over the low or the median quality limit were located mainly in the South Yellow Sea. The fractions and specific ratios of DDTs suggested that new inputs of DDT existed at two sites in the North Yellow Sea, and the potential sources involved technical DDT, technical dicofol, and their mixture.