Methacrolein(MACR) and methyl vinyl ketone(MVK) are two major intermediate products from the photochemical oxidation of isoprene, the most important biogenic volatile organic compound. In addition, MACR and MVK have primary emissions. Investigating the sources and evolution of MACR and MVK could provide helpful information for the oxidative capacity of the atmosphere. In this study, hourly measurements of isoprene, MACR, and MVK were conducted at a receptor site in the Pearl River Delta region(PRD), i.e., the Heshan site(HS), from 22 October to 20 November, 2014. The average mixing ratios of isoprene,MACR and MVK were 151 ± 17, 91 ± 6 and 79 ± 6 pptv, respectively. The daily variations and the ratios of MVK/MACR during daytime and nighttime suggested that other sources besides isoprene photooxidation influenced the MACR and MVK abundances at the HS.Positive matrix factorization was utilized to resolve the sources of MACR and MVK. Five sources were identified and quantified, including biogenic emissions, biomass burning,secondary formation, diesel, and gasoline vehicular emissions. Among them, secondary formation made the greatest contribution to observed MACR and MVK with average contributions of ~ 45% and ~ 70%, respectively. Through the yields of secondary products from the oxidation of MACR and MVK by the OH radical and the concentrations of MACR and MVK, it was found that methylglyoxal and formaldehyde were the main oxidation products of MACR and MVK at the HS site. Overall, this study evaluated the roles of primary emissions on ambient levels of MACR and MVK and advanced the understanding of photochemical oxidation of MACR and MVK in the PRD. 相似文献
Municipal solid waste(MSW) incineration has become an important anthropogenic source of heavy metals(HMs) to the environment. However, assessing the impact of MSW incineration on HMs in the environment, especially soils, can be a challenging task because of various HM sources. To investigate the effect of MSW incineration on HMs in soils, soil samples collected at different distances from four MSW incinerators in Shanghai, China were analyzed for their contents of eight HMs(antimony, cadmium, chromium, copper,lead, mercury, nickel, and zinc) and lead(Pb) isotope ratios. Source identification and apportionment of HMs were accomplished using principal component analysis and Pb isotope analysis. Results indicated that the relatively high contents of cadmium, lead,antimony, and zinc in the soils at 250 m and 750–1250 m away from the MSW incinerators were related to MSW incineration, while the elevated contents of the other four HMs were associated with other anthropogenic activities. Based on Pb isotope analysis, the contribution ratio of MSW incineration(which had been operated for more than 14 years)to the accumulation of Pb in soil was approximately 10% on average, which was lower than coal combustion only. Incinerator emissions of Pb could have a measurable effect on the soil contamination within a limited area(≤1500 m). 相似文献
In order to study how water level fluctuations (WLF) of reservoir influence the macroinvertebrate in tributary bay, we studied the effect of WLF of the Three Gorges Reservior on macroinvertebrate communities in Xiangxi Bay, and the time lags of such effect, based on the surveys in spring and summer from 2005 to 2010. In this research, WLF was represented by water level drawdown (WLD) and the sum of absolute values of rate of water level fluctuations (RWlf). Pearson correlation analysis was used to analyze the relationship between WLF and macroinvertebrates. No significant correlation was found between macroinvertebrates and sum of absolute values of RWLF, while WLD showed significant influence on some biotic parameters. In spring, WLD did not cause significant effect to macroinvertebrates (P > 0.05). In summer, however, the influence was significant, especially in the area of the downstream (XX01 - XX02) of the Xiangxi Bay (P < 0.05). The middle reach of the bay (XX05), located in the conjunction area between Xiangxi Bay and a secondary tributary of the TGR, was also affected significantly (P < 0.05). The relative abundance of Tubificidae declined with the increase of the WLF, while abundance of Chironomidae increased. The time lags of the influence to macroinvertebrates were about 15 days. This analysis indicated that WLF in the mainstream of the reservoir mainly influences the downstream of the tributary bay, and also affects the conjunction area of the secondary tributary. Chironomidae are more tolerant than Tubificidae in water-body with dramatic disturbance, therefore can be considered as the indicator of the effect of summer WLF on macroinvertebrates. 相似文献
Water pollution by antibiotics is an increasing concern, which may be addressed by advanced oxidation processes using sulfites as precursors of sulfate radicals (SO4·–), yet the efficiency of sulfite activation is limited. Here, we tested copper cobalt sulfide (CuCo2S4) to activate sulfite, based on the synergy among transition metals and the facilitation of transition metal redox circulation by reductive sulfur species. We analyzed CuCo2S4 structure by X-Ray photoelectron spectroscopy, and we studied the effect of pH and radical scavengers. Results show 90–100% abatement of tetracycline concentration at pH 8.0–10.0, with SO4·– and HO· as the main reactive radicals. This finding is explained by the accelerated redox recycling of copper and cobalt by sulfur, and by the synergetic effect between active cobalt and copper sites.
• Aerosolization behavior during a lab-scale sludge biostabilization was determined.• Many pathogenic species were identified to be preferentially aerosolized.• Bioaerosol concentration along the biostabilization ranged from 160 to 1440 cell/m3.• Sludge aerosolization behavior was different with that of other biowaste. Biostabilization is a cost-effective method for the beneficial utilization of sewage sludge. However, during the operation of sludge biostabilization, some microbial species could be released into the atmospheric environment from the solid-phase of sludge easily and present a high risk to human health. This study aimed to evaluate the risk of bioaerosol during sludge biostabilization. We found a total of nine bacterial phyla, one archaeal phylum, and two fungal phyla in the bioaerosol samples. Among them, Proteobacteria, Actinobacteria, Bacteroidetes, and Ascomycota were the dominant phyla. In addition, the bioaerosolization indexes (BI) of prokaryotic phyla and fungal phyla ranged 0–45 and 0–487, respectively. Massilia, Pseudarthrobacter, Pseudomonas, Tremellales spp., and Fusarium were the preferentially aerosolized microbial genera with maximum bioaerosolization indexes of 19962, 10360, 1802, 3055, and 7398. The bioaerosol concentration during the biostabilization ranged from 160 to 1440 cell/m3, and we identified species such as Stenotrophomonas rhizophila and Fusarium graminerum with high bioaerosolization indexes that could be threats to human health. Euryachaeota, which belongs to archaeal phyla, had the highest biostabilization index in our study. We also found that Pseudarthrobacter was the easiest to aerosolize during the sludge biostabilization process. 相似文献