Emission characteristics of polycyclic aromatic hydrocarbons from combustion of different residential coals in North China.

Emission properties of polycyclic aromatic hydrocarbons (PAHs) from combustion of six residential coals in North China were investigated. The results indicated that, the total emission factors (EFs) for 15 PAH species in gaseous and particulate phases ranged from 52.8 to 1434.8 mg/kg with a decreasing sequence of local bituminous coals and anthracite coals, and honeycomb briquettes were largely dependent on the raw coals used to produce them. Particulate phase, dominated by median or high molecular weight components, made a major contribution (68.8%-76.5%) to the total EFs for bituminous coals, while gaseous phase with principal low molecular weight species accounted for most (86.3%-97.9%) of the total EFs for anthracite coals. The phase partitioning of PAH emission for honeycomb briquettes was similarly dependent on the crude coals. The total EFs, phase partitioning and component profiles of emitted PAHs were mainly influenced by the inner components of the studied coals. Burning mode and flue number on household coal-stoves also affected the emission characteristics by means of the oxygen supply. A sum of seven carcinogenic PAHs, benzo(a)pyrene(BaP)-equivalent carcinogenic power and total toxicity potency expressed in 2,3,7,8-tetrachlorodibenzo-dioxin(TCDD) toxic equivalence exhibited that bituminous coals and produced honeycomb briquettes had remarkably elevated values. Fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene and indeno(1,2,3-cd)pyrene from anthracite coals showed higher levels of BaP-based toxic equivalent factor, though the other toxicity indices were rather low for this type of coal.

Distribution of persistent toxic substances in benthic bivalves from the inshore areas of the Yellow Sea.

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.

A novel pretreatment approach for fast determination of organochlorine pesticides in biotic samples.

Recent studies have focused on enantiomeric behaviors of chiral organochlorine pesticides (OCPs) in biotic matrix because they provide insights into the biotransformation processes of chiral OCPs. In the present paper, a double in-line column chromatographic method was developed to effectively remove the lipid impurity in different biotic samples for clean-up of OCPs. After an initial Soxhlet extraction of OCPs from the biotic samples by a mixture of acetone and dichloromethane (DCM), dimethyl sulfoxide (DMSO) was directly added to the extract, and low boiling point solvents (acetone and DCM) were then evaporated. OCPs remained in DMSO were eluted via column 1 filled with silicon gel, and subsequently passed through column 2 packed with 15% deactivated florisil. This novel method was characterized by significant time and solvent savings. The recovery rates of alpha-HCH (hexachlorocyclohexane), beta-HCH, gamma-HCH and delta-HCH were 78.5+/-3.1%, 72.4+/-7.7%, 72+/-4.0% and 70.0+/-8.7%, respectively, and 92.5+/-3.8%, 79.7+/-6.7% and 83.4+/-6.5% for 1,1-dichloro-2-(2-chlorophenyl)-2-(4- chlorophenyl) ethylene (o,p'-DDE), 1,1-dichloro-2-(2-chlorophenyl)-2-(4-chloro phenyl)ethane (o,p'-DDD) and 1,1,1-trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl) ethane (o,p'-DDT), separately. In addition, the separation efficiencies of the target compounds by both achiral and chiral gas chromatographic columns were satisfactory using the established method. Therefore, the double in-line column chromatography was a useful alternative method for pretreatment of OCPs in different biotic samples.

Polycyclic aromatic hydrocarbon (PAH) concentrations in the dissolved, particulate, and sediment phases in the Luan River watershed, China.

Water and sediment samples were collected from the Luan River and its 5 tributaries to determine polycyclic aromatic hydrocarbons (PAHs) concentrations in dissolved, particulate, and sediment phases. The Luan River watershed, located in northeastern Hebei province, provides water to population centers such as Tianjian and Tangshan. Sampling locations were chosen at areas not under direct influence of industrial activities to examine the "background" PAH contamination across the watershed. PAH concentrations in the dissolved, particulate, and sediment phases ranged from 11.5 ng/L to 171.5 ng/L, 152.8 ng/g. d.w. to 1372.3 ng/g d.w., and 6.7 to 1585.7 ng/g d.w., respectively. Low molecular weight PAHs (with 2 to 3 rings) dominated the dissolved and particulate phases, whereas medium and high molecular weight PAHs (with 4 to 6 rings) dominated the sediment phase. The isomer ratios of PAHs in sediments indicated that PAHs in Luan River originated from combustion processes and those PAHs underwent long-distance transport.

Distribution and property of polycyclic aromatic hydrocarbons in littoral surface sediments from the Yellow Sea, China.

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.