An assessment of polyurethane foam passive samplers for atmospheric metals compared with active samplers.

In this study, we conducted an assessment of polyurethane foam (PUF) passive sampling for metals combining active sampling. Remarkably, we found that the metals collected in the passive samples differed greatly from those collected in active samples. By composition, Cu and Ni accounted for significantly higher proportions in passive samples than in active samples, leading to significantly higher uptake rates of Cu and Ni. In assessing seasonal variation, metals in passive samples had higher concentrations in summer (excluding Heshan), which differed greatly from the pattern of active samples (winter > summer), indicating that the uptake rates of most metals were higher in summer than in winter. Overall, due to the stable passive uptake rates, we considered that PUF passive samplers can be applied to collect atmospheric metals. Additionally, we created a snapshot of the metal pollution in the Pearl River Delta using principal component analysis of PUF samples and their source apportionment.

Historical records of polycyclic aromatic hydrocarbon deposition in a shallow eutrophic lake: Impacts of sources and sedimentological conditions.

Sediment core samples collected from Lake Chaohu were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to assess the spatial and temporal distributions of the PAHs during lacustrine sedimentary processes and regional economic development. Assessing the PAH sedimentary records over an approximately 100-year time span, we identified two stages in the PAH inputs and sources (before the 1970s and after the 1970s) in the eastern lake region near a village, whereas three stages (before the 1950s, 1950s-1990s and after the 1990s) were identified in the western lake region near urban and industrial areas. Rapid increases in the PAH depositional fluxes occurred during the second stage due to increased human activities in the Lake Chaohu basin. The composition and isomeric ratios of the PAHs revealed that pyrolysis is the main source of PAHs in this lake. Strong positive relationships between PAH concentration and the total organic carbon concentration, sediment grain size (<4µm), as well as the local population and Gross Domestic Product indicated that the sedimentary conditions impact the depositional characteristics of the PAHs; simultaneously, socioeconomic activities, such as energy consumption and the levels of urban industrialization and civilization, affect both the composition and abundance of the PAHs.

Distribution, source, and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Hun River, northeast China.

In this study, the occurrence and distribution of 16 polycyclic aromatic hydrocarbons (PAHs), listed by the United States Environmental Protection Agency (US EPA), were investigated in surface sediment samples from the Hun River, northeast China. The data was then used to assess the potential ecological risk. The results indicated 15 PAHs were detected in these sediments, and the total concentrations of the 15 PAHs (not including naphthalene) ranged from 82.96 to 39,292.95 ng g(-1) dry weight (dw), with an average value of 3705.54 ng g(-1) dw, and 4-ring PAHs were the dominant compounds at most sites. The diagnostic parameters such as anthracene/(anthracene + phenanthrene), fluoranthene/(fluoranthene + pyrene), and indeno[1,2,3-cd]pyrene/(indeno[1,2,3-cd]pyrene + benzo[g,h,i]perylene) showed that they had been emitted from a number of different sources, especially the pyrolytic emissions. The results of the ecological risk assessment, which compared the PAH concentrations with the effect range low (ERL) and the effect range median (ERM) values, indicated that several individual PAH concentrations at four sites in the downstream section of the Hun River were higher than the ERM, suggesting that there was a potential ecological risk in these areas.

Spatial distribution, potential risk assessment, and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments of Lake Chaohu, China.

Twenty-nine sediment samples were collected from Lake Chaohu, a shallow eutrophic lake in Eastern China, and were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to determine the spatial distribution and exposure risks of PAHs. Three receptor models, the principal component analysis-multiple linear regression (PCA-MLR) model, the positive matrix factorization (PMF) model, and the Unmix model, were used in combination with the PAHs diagnostic ratios to investigate the potential source apportionment of PAHs. A clear gradient in the spatial distribution and the potential toxicity of PAHs was observed from west to east in the sediments of Lake Chaohu. ∑15PAH concentrations and the TEQ were in the range of 80.82-30 365.01 ng g(-1) d.w. and 40.77-614.03, respectively. The highest values of the aforementioned variables were attributed to urban-industrial pollution sources in the west lake region, and the levels decreased away from the river inlets. The three different models yielded excellent correlation coefficients between the predicted and measured levels of the 15 PAH compounds. Similarly, source apportionment results were derived from the three receptor models and the PAH diagnostic ratios, suggesting that the highest contribution to the PAHs was from coal combustion and wood combustion, followed by vehicular emissions. The PMF model yielded the following contributions to the PAHs from gasoline combustion, diesel combustion, unburned petroleum emissions, and wood combustion: 34.49, 24.61, 16.11, 13.01, and 11.78 %, respectively. The PMF model produced more detailed source apportionment results for the PAHs than the PCA-MLR and Unmix models.

Occurrence and carcinogenic potential of airborne polycyclic aromatic hydrocarbons in some large-scale enclosed/semi-enclosed vehicle parking areas.

Polycyclic aromatic hydrocarbons (PAHs) originating from vehicle exhaust have aroused much attention due to their potential healthy effect. In this study, air samples were collected from three representative parking lots in a metropolitan area, analyzed for PAHs and evaluated for inhalation risk. Atmospheric PAH levels of these parking areas ranged between 1,178-4,793 ng m(-3), one order of magnitude higher than general urban areas. Their benzo[a]pyrene equivalent (BaPeq) values varied in 11.0-98.0 ng m(-3), far exceeding the air quality standard of WHO (1.0 ng m(-3)). Monte Carlo simulation (100,000 trials) results suggest that the potential lifetime inhalation cancer risks of PAHs were 0.27 × 10(-5) to 7.11 × 10(-5) for park employees, which are in the acceptable range acknowledged by US EPA (1.0 × 10(-6) to 1.0 × 10(-4)). Several source diagnostic methods proved that vehicle exhaust was the dominant PAH contributor of these parks with the contribution percentages being >53%; oil combustion and/or coal combustion were other important sources. Logarithms of gas-particle distribution coefficients (Kps) of PAHs in all studied parks were linearly correlated with those of both their sub-cooled vapor pressures (pLs) and octanol-air partition coefficients (KOAs). The correlation coefficients indicated that both adsorption onto black carbon and absorption into organic matter were involved in the partition process, but the latter was dominant.

Musks and organochlorine pesticides in breast milk from Shanghai, China: levels, temporal trends and exposure assessment.

The concentrations of musks (polycyclic musks and nitro musks) and traditional organochlorine pesticides (OCPs), including dichlorodiphenyltrichloroethane and its metabolites (DDT, DDE, DDD, and total DDTs), hexachlorobenzene (HCB), and hexachlorocyclohexanes (HCHs) in breast milk collected in Shanghai, China during the period 2006-2010, were determined. The total concentrations ranged from 4.7 to 276.2 (median: 58.4) ng/glipid weight (lw) for musks and from 88.3 to 2532.9 (median: 1003.8) ng/glw for OCPs. 4,4'-DDE (median: 655.4 ng/glw) was the predominant OCP, followed by ß-HCH (median: 172.5 ng/g lw), and HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran) (median: 17.7 ng/g lw) was the dominant musk. There was no statistical correlation between total musk concentrations, and HCB, HCHs, DDTs or total OCP concentrations, indicating their different exposure routes and metabolism in humans (p=0.182-0.325). Clear reductions in temporal trends in the levels of DDTs and HCB, especially HCHs (p<0.01) were observed during the sampling period, and the high DDE/DDT ratios in the samples indicated past exposure to DDTs. The relatively high median concentrations of HHCB and HHCB-lactone in 2010 suggested a probably increasing tendency. There were statistically significant influences regarding maternal age and parity on OCP accumulation (p=0.001-0.002), but no significant effect on musks was found (p=0.542-0.919). Musk exposure in neonates via breast milk was 2-3 orders of magnitude lower than suggested provisional tolerable daily intakes (PTDI). The estimated daily intakes for HCB and DDTs were below the PTDI in Canada, however, 56% of those for HCHs exceeded the Canadian PTDI. OCP contamination of breast milk requires further attention.

[Method of ecological risk assessment for risk pollutants under short-term and high dose exposure in water pollution accident].

In recent years, water pollution accidents resulting in acute aquatic ecological risk and security issues become a research focus. However, in our country, the surface water quality standards and drinking water health standards were used to determine the safety of waters or not in pollution incidents due to lacking safety effect threshold or risk value for protection of aquatic life. In foreign countries, although predicted no effect concentration (PNEC) or risk value (R) of pollutants were provided for protection of aquatic organisms, the PNECs or risk values were derived based on long-term exposure toxicity data NOECs (no observed effect concentrations) and lack of short-term exposure risk or threshold values. For the short-term and high dose exposure in pollution incident, ecological risk assessment methods were discussed according to the procedures of the conventional ecological risk assessment and the water quality criteria establishment of the U.S. EPA for the protection of aquatic organisms in short-term exposure, and had a case study. At the same time, we provide some suggestions for the establishment of ecological risk assessment system in water pollution incidents.

Safety assessment of the source water within the Pearl River Delta on the aspect of organochlorine pesticides contamination.

The safety of source water is a noticeable problem in the Pearl River Delta, one of the densely populated areas in China. In this study, 20 individual organochlorine pesticides (OCPs) were investigated in 15 water sources within this area using gas chromatography-electron capture detector, and the hazard risks to human health were assessed in terms of individual OCPs based on daily water consumption according to the standard recommended by the United States Environmental Protection Agency. Results showed that the total OCP concentrations ranged from 2.42 ng l(-1) to 39.52 ng l(-1) during the years 2008 and 2009. The hazard ratios based on both non-cancer and cancer benchmarks were less than 1 for all the water samples, which indicated that individual OCPs posed no risk to human health. However, the risks caused by the combined toxicity of total OCPs in this area should not be ignored.

Mutagenicity assessment of produced water during photoelectrocatalytic degradation.

Oilfield produced water was treated by photocatalysis, electro-oxidation, and photoelectrocatalysis, respectively. The chemical composition and toxicity of the raw effluent and treated products were assessed by chemical and mutagenicity analysis. The raw effluent exhibited mutagenic activity in both strains of Salmonella typhimurium. The lowest concentration of the dichloromethane extract capable of inducing a positive response in strains TA98 and TA100 were as low as 4 and 5 microg/plate, respectively. All three technologies could detoxify direct-acting mutagenic organic pollutants efficiently, although they could not completely eliminate mutagenicity in the water after 60 min of treatment. At equivalent doses, photoelectrocatalysis exhibited the greatest capability to reduce genotoxicity, whereas photocatalysis was the least effective and did not cause appreciable change in mutagenicity. The gas chromatography-mass spectrometry (GC-MS) analysis revealed that n-alkanes (259.4 ng/L) and phenolic compounds (2,501.4 ng/L) were the main organic constituents in the oilfield produced water. Thus, the results of both biological and chemical analysis indicate that photoelectocatalysis was the most effective technology for degradation of oilfield wastewater.