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Poly-β-hydroxy butyric acid (PHB) accumulation and gaseous H 2 release are regarded as alternatives for expending reducing power. Some researchers suggested that quorum-sensing system affects PHB accumulation in Rhodobacter sphaeroides , but whether the system plays regulation role between hydrogen producing and PHB synthesis is still unknown. By adding autoinducer of R. sphaeroides into its culture solutions, measuring its total hydrogen production, PHB content and PHB synthase activity, the function of quorum-sensing on PHB accumulation and hydrogen production was preliminarily investigated. Compared with the control, the total gas productions in experimental groups increased accompanying slight decrease of PHB contents, which was partially caused by the reduction of PHB synthase activities. Biolog tests indicated the carbon source utilization profiles, especially those involving fatty acids and butanoate metabolism, had partly changed after exogenous signal molecules added. These results suggest that quorum-sensing is involved in signal regulation between PHB accumulation and hydrogen production in R. sphaeroides .

Concentrations of non-methane hydrocarbons (NMHCs) were measured to investigate their temporal variations and major sources, and to explore the ozone formation potentials (OFP) of each NMHCs for the first time in December 2008 in Foshan. Ethane, propane, n-butane, i-pentane, 2,3-dimethylbutane, ethene, propene, ethyne, benzene and toluene were the 10 most abundant hydrocarbons, accounting for 82% of the concentration of total NMHCs. Concentrations of these hydrocarbons as well as their fractional contributions to the total NMHCs were higher in the morning and evening than in the afternoon, consistent with the variations in vehicle volumes during these periods. This suggests that the vehicular emission was likely the major source of NMHCs at this site. The mean B/T ratio (0.45 ± 0.24) further supported vehicular emission as the main source of the ambient NMHCs except for aromatic hydrocarbons. These aromatic hydrocarbons were mainly from solvent evaporation, as indicated by the diurnal variations in the ratios of toluene and m/p-xylene to benzene. The results from factor analysis also showed that combustion process and solvent usage were the major sources of NMHCs. On average, total Prop-Equiv and OFP were 153.0 ppbc and 863.4 μg/m 3 , respectively. Based on MIR (maximum incremental reactivity) scale, the leading contributors to OFP in decreasing concentrations were ethene, toluene, propene, i-pentane, m/p-xylene, 1-butene, ethylbenzene, o-xylene, 2,3-dimethylbutane and trans-2-butene, which in total explained 77% of the total OFP. Ranking by Prop-Equiv, the top 10 species were propene, toluene, ethene, 1-butene, i-pentane, m/pxylene, isoprene, 2,3-dimethylbutane, trans-2-butene and ethylbenzene, accounting for 66% of the total Prop-Equiv. Thus, alkenes played the most important role in O3 formation, followed by aromatics and alkanes during the study periods in Foshan.

With high occurrence of sudden water pollution incident, China faces an increasingly severe situation of water environment. In order to deter the acts of environmental pollution, ensure the damaged resources of environment can be restored and compensated, it is very critical to quantify the economic losses caused by the sudden water pollution incident. This paper took truck rollover pollution incidents in Chongqing for an example, established a set of evaluation method for quantifying the environmental damage, and then assessed the environmental damage by the method from four aspects, including the property damage, ecological environment and resources damages, the costs of administrative affairs in emergency disposal, and the costs of investigation and evaluation.

PM2.5 was sampled from commercial, industrial and residential areas in Chongqing urban city from 2nd May to 10th May 2012 in order to find out characteristics and sources of carbon in PM2.5. Eight kinds of carbons were analyzed by the TOR method. Characteristics of carbon pollution in PM2.5 from three kinds of functional areas and six kinds of sources, including coal-combustion, exhausts (vehicle, boat and construction machine), biomass burning, cooking smoke, were analyzed. Based on carbon source profiles, local indicating components of carbon sources in PM2.5 were obtained used the chemical mass balance (CMB) model. Contribution rate of different sources to PM2.5 carbon were parsed out by factor analysis. The results showed the OC/EC of coal-combustion, vehicle exhausts, boat exhausts, construction machine exhausts, biomass burning and cooking smoke were 6.3, 3.0, 1.9, 1.4, 12.7 and 31.3, respectively. High loads of EC2 and EC3 indicated diesel vehicle exhaust emissions, high loads of OC2, OC3, OC4 and OPC indicated coal-combustion emissions, OC1, OC2, OC3, OC4 and EC1 indicated gasoline vehicle exhaust emissions, OC3 indicated cooking emissions, and OPC indicated biomass burning emissions. OC/PM2.5, EC/PM2.5, secondary organic carbon (SOC)/OC in the commercial area were 17.4%, 6.9% and 40.0%, respectively. OC/PM2.5, EC/PM2.5 and SOC/OC in the industrial area were 15.5%, 6.6% and 37.4%, respectively. OC/PM2.5, EC/PM2.5 and SOC/OC in the residential area were 14.6% 5.6% and 42.8%, respectively. In the industrial area, the main sources of carbon in PM2.5 were coal combustion, gasoline vehicle exhausts and diesel exhaust. In the commercial area, the main sources of carbon were gasoline vehicle exhausts, diesel exhausts and cooking. In the residential area, the main sources of carbon were gasoline vehicle exhausts, cooking smoke and diesel exhausts.

[1] Distinct contrast of air quality and visibility before and during the 2008 Beijing Olympic Games provides a rare opportunity to investigate the links between PM2.5 mass, chemical composition, and light extinction in this megacity. Twenty-four hour integrated PM2.5 samples were collected, and light scattering coefficients and the concentrations of black carbon were measured at urban Beijing for this purpose during a measurement campaign from 1 July to 20 September 2008, which was classed into four stages according to the levels of emission control measures. Daily PM2.5 concentrations ranged from 15.9 to 156.7 µg m−3 with an average of 66.0 ± 35.1 µg m−3. The average PM2.5 mass during the Olympics decreased by 49% from the second stage (20 July to 7 August), mainly due to the reduction of secondary inorganic aerosols (i.e., sulfate, nitrate, and ammonium (SNA)). The counterintuitive increase of PM2.5 mass (by 27% on average) during the second stage with two most serious haze episodes, although more rigorous emission control measures were in place, compared to the first stage (1–19 July), was mainly explained by the unfavorable meteorology and input of sulfate aerosols. A daily PM2.5 mass threshold of 50 µg m−3 was extracted for frequent haze occurrence. The extinction fractions of SNA and organic material were each approximately 30% during the 20% best visibility days but changed to 81.7% and 8.4%, respectively, during the 20% worst visibility days. The results indicated that the role of SNA was magnified in haze formation during the 2008 summer in Beijing.