Pollutants in Hong Kong soils: polycyclic aromatic hydrocarbons

The status of soil contamination by semivolatile organic chemicals (SVOCs) in China: a review

This paper summarizes the published scientific data on the soil contamination by semivolatile organic chemicals (SVOCs) in China. Data has been found for more than 150 organic compounds which were grouped into six classes, namely, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and phthalic acid esters (PAEs). An overview of data collected from the literature is presented in this paper. The Chinese regulation and/or other maximum acceptable values for SVOCs were used for the characterization of soils. In general, the compounds that are mostly studied in Chinese soils are OCPs, PAHs and PCBs. According to the studies reviewed here, the most abundant compounds were PAEs and PAHs (up to 46 and 28 mg kg(-1) dry weight, respectively); PCBs and OCPs occurred generally at concentrations lower than 100 microg kg(-1) dry weight. Nevertheless, quite high concentrations of PCDD/Fs, PCBs and PBDEs were observed in contaminated sites (e.g., the sites affected by electronic waste activities). The average concentrations of PAHs and OCPs in soils of North China were higher than those in South China. The principal component analysis demonstrated different distribution patterns for PAH, PCB and PCDD/F congeners and for the various sites/regions examined. The isomer ratios of DDTs and hexachlorocyclohexanes (HCHs) indicated different sources and residue levels in soils. Finally, this review has highlighted several areas where further research is considered necessary.

Impact of toasting oak barrels on the presence of polycyclic aromatic hydrocarbons in wine

Toasting Quercus sp. oak wood is one of the key stages in manufacturing barrels intended for aging wines and spirits. During this operation, the increase in temperature causes variable modifications in the physical structure and, more importantly, the chemical composition of the wood. Polycyclic aromatic hydrocarbons (PAH) are high-risk molecules likely to be formed during toasting of the wood and later extracted by wine or spirits in direct contact with the barrel. In the context of an analysis of all potential sources of risk associated with the manufacture of barrels for winery use [prevention policy defined using a Hazard Analysis Critical Control Point (HACCP) approach], we carried out a preliminary study to provide a more accurate assessment of potential risks related to the presence of PAH in cooperage and winemaking. Wood toasted to different levels under different conditions, as well as wines aged in barrels made using different methods, was analyzed by gas chromatography and mass spectrometry (GC-MS) for the identification of the main PAH present, quantification of each of the molecules extracted, and estimation of any possible toxicological risks, via a comparison of values with those measured in other types of food. The results clearly showed that the heating processes associated with barrel production actually resulted in the formation of various molecules in the PAH family. However, only a minority of the target PAH presented high toxicity, particularly carcinogenic potential. Because of the specific toasting process used, benzo[a]pyrene, the best-known, and one of the most dangerous, contaminants, was not significantly present in toasted barrel wood. In view of the PAH concentrations in wood and the low solubility of these compounds, their extraction in wine is apparently relatively slow and limited. Finally, comparing the overall PAH concentrations, and particularly those of the most toxic compounds, with estimated absorption from food or the environment, we found it was obvious that the contribution of toasted barrels to the total amount was extremely low and should not, therefore, be considered a major health concern.

Quantification and source identification of polycyclic aromatic hydrocarbons in sediment, soil, and water spinach from Hanoi, Vietnam

Polycyclic aromatic hydrocarbons (PAHs) were quantified in sediment, soil, and plant material from Hanoi, Vietnam, and an aquatic production system in peri-urban Hanoi. The sum of the concentration of 16 US-EPA priority PAHs ( summation PAH16) ranged between 0.44 and 6.21 mg kg(-1) dw in sediment and between 0.26 and 1.35 mg kg(-1) dw in soil, with decreasing concentrations from the urban area to the peri-urban area, indicating contributions from urban and industrial sources. Double plots of diagnostic source ratios indicate that PAHs originate from mixed petrogenic and pyrogenic sources, the latter being predominant. The predominance of low molecular weight (LMW) PAHs in the sediment samples suggests that petrogenic sources are more prevalent in the water environment than in the soil. In contrast, high molecular weight (HMW) PAHs dominated in water spinach which probably reflects the plant's uptake of particle-bound PAHs that originate from pyrogenic sources.