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Результаты 91-100 из 2,513
Inter-compartmental transport of organophosphate and pyrethroid pesticides in South China: Implications for a regional risk assessment Полный текст
2014
Li, Huizhen | Wei, Yanli | Lydy, Michael J. | Yau, Ching
The dynamic flux of an organophosphate and four pyrethroid pesticides was determined in an air-(soil)-water-sediment system based on monitoring data from Guangzhou, China. The total air–water flux, including air–water gaseous exchange and atmospheric deposition, showed deposition from air to water for chlorpyrifos, bifenthrin and cypermethrin, but volatilization for lambda-cyhalothrin and permethrin. The transport of the pesticides from overlying water to sediment suggested that sediment acted as a sink for the pesticides. Additionally, distinct annual atmospheric depositional fluxes between legacy and current-use pesticides suggested the role of consumer usage in their transport throughout the system. Finally, pesticide toxicity was estimated from annual air–water-sediment flux within an urban stream in Guangzhou. A dynamic flux-based risk assessment indicated that inter-compartmental transport of chlorpyrifos decreased its atmospheric exposure, but had little influence on its aquatic toxicity. Instead, water-to-sediment transport of pyrethroids increased their sediment toxicity, which was supported by previously reported toxicity data.
Показать больше [+] Меньше [-]Sorption of phenanthrene and benzene on differently structural kerogen: Important role of micropore-filling Полный текст
2014
Zhang, Yulong | Ma, Xiaoxuan | Ran, Yong
Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (Vo,d) initially increase and then decrease. The Vo,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The Vo,d of phenanthrene and benzene on the kerogen samples accounts for 23–46% and 36–65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling.
Показать больше [+] Меньше [-]Why small and medium chemical companies continue to pose severe environmental risks in rural China Полный текст
2014
He, Guizhen | Zhang, Lei | Mol, Arthur P.J. | Wang, Tieyu | Lü, Yonglong
In China, rural chemical SMEs are often believed to still largely operate below the sustainability radar. This paper investigates to what extent and how chemical SMEs are already experiencing pressure to improve their environmental performance, using an in-depth case study in Jasmine County, Hebei province. The results show that local residents had rather low trust in the environmental improvement promises made by the enterprises and the local government, and disagreed with the proposed improvement plans. Although the power of local residents to influence decision making remained limited, the chemical SMEs started to feel increasing pressures to clean up their business, from governments, local communities and civil society, and international value chain stakeholders. Notwithstanding these mounting pressures chemical SME's environmental behavior and performance has not changed radically for the better. The strong economic ties between local county governments and chemical SMEs continue to be a major barrier for stringent environmental regulation.
Показать больше [+] Меньше [-]Incubation stage and polychlorinated biphenyl (PCB) congener patterns in an altricial and precocial bird species Полный текст
2014
Custer, Christine M. | Custer, Thomas W. | Thyen, Stefan | Becker, Peter H.
The composition of polychlorinated biphenyl (PCB) congeners was compared between non-incubated and embryonated eggs of tree swallows (Tachycineta bicolor) and little terns (Sterna albifrons) to determine if measurable changes in PCB congeners occurred during the embryonic period. There was no indication of changes in PCB congener patterns over the incubation period in tree swallows in 1999 and 2000 at a site with very high PCB exposure or a site with more modest PCB exposure. Additionally, congeners known to be either quickly metabolized or conserved based on experimental studies did not generally respond as predicted. Similarly, PCB congener patterns in eggs of little terns from Bottsand, Schleswig-Holstein, Germany, did not differ between non-incubated and embryonated eggs. The results from both species suggest that the stage of incubation is not an important consideration when evaluating PCB congener patterns; comparisons and assessments can be made with eggs collected at all stages of incubation.
Показать больше [+] Меньше [-]Soil physical characteristics after EDTA washing and amendment with inorganic and organic additives Полный текст
2014
Zupanc, Vesna | Kastelec, Damijana | Lestan, Domen | Grcman, Helena
Soil washing has been established as suitable remediation technology, with most research focused on metal removing efficiency and toxic effect on plants, less on the influence on soil physical characteristics, which was the focus of this study. In soil column experiment highly contaminated soil and soil washed with EDTA, mixed with additives (gypsum, hydrogel, manure, peat) were tested. White clover was used as a soil cover. Yield, metal concentration in soil and plant, aggregate fractionation and stability, saturated hydraulic conductivity and soil water retention of the soil were measured. Soil washing decreased metal concentration in soil and plants, but yield of white clover on remediated soil was significantly lower compared to the original soil. Significant differences in water retention characteristics, aggregate fractionation and stability between original and remediated soil have been determined. Gypsum, hydrogel and peat increased plant available water, manure and peat increased yield on remediated soil.
Показать больше [+] Меньше [-]Ozone phytotoxic potential with regard to fragments of the Atlantic Semi-deciduous Forest downwind of Sao Paulo, Brazil Полный текст
2014
In the Metropolitan Region of Campinas (MRC), Brazil, high levels of primary pollutants contribute to ozone (O3) formation. However, little is known regarding the O3 effects in the tropics. Objectives in this study were to characterize the present levels of O3 pollution and to evaluate the relevance of current concentration-based indices for assessing the phytotoxic potential of O3. Changes in O3 concentrations and precursors at 5 monitoring stations within towns of MRC were analyzed. The daily O3 profile was typical for urban sites and showed little yearly variation. Given the permanently foliated forest canopy, yearly rather than seasonal O3 indices were thus more appropriate for estimating the effective ozone dose. With yearly SUM00, SUM60 and AOT40 of 156, 16 and 14 ppm h and confirmed by evidence of O3 injury in foliage, oxidative stress in the MRC has reached levels high enough to affect trees from the Atlantic Semi-deciduous Forest.
Показать больше [+] Меньше [-]Atmospheric transport and accumulation of organochlorine compounds on the southern slopes of the Himalayas, Nepal Полный текст
2014
Studies have been devoted to the transport and accumulation of persistent organic pollutants (POPs) in mountain environments. The Himalayas have the widest altitude gradient of any mountain range, but few studies examining the environmental behavior of POPs have been performed in the Himalayas. In this study, air, soil, and leaf samples were collected along a transect on the southern slope of the Himalayas, Nepal (altitude: 135–5100 m). Local emission occurred in the lowlands, and POPs were transported by uplift along the slope. During the atmospheric transport, the HCB proportion increased from the lowlands (20%) to high elevation (>50%), whereas the proportions of DDTs decreased. The largest residue of soil POPs appeared at an altitude of approximately 2500 m, and may be related to absorption by vegetation and precipitation. The net deposition tendencies at the air–soil surface indicated that the Himalayas may be a ‘sink’ for DDTs and PCBs.
Показать больше [+] Меньше [-]Can Coronene and/or Benzo(a)pyrene/Coronene ratio act as unique markers for vehicle emission? Полный текст
2014
Shen, Guofeng | Chen, Yuanchen | Wei, Siye | Fu, Xiaofang | Ding, Aijun | Wu, Haisuo | Tao, Shu
Coronene is a high molecular weight polycyclic aromatic hydrocarbon with seven aromatic rings. It, more specifically a lower ratio of Benzo[a]pyrene to Coronone (BaP/COR), is suggested as a marker for vehicle emission. In the present study, emissions of Coronene were measured from residential combustions of wood, crop straw, and pellets. The detection of COR in non-vehicle emission sources, and comparable BaP/COR ratios between the solid fuel combustion and vehicle emissions indicated that the generality of COR or the BaP/COR ratio as markers for the vehicle emission would be questionable, especially for the area where solid fuel combustion dominated the PAHs emission.
Показать больше [+] Меньше [-]Decreasing effect and mechanism of FeSO4 seed particles on secondary organic aerosol in α-pinene photooxidation Полный текст
2014
Chu, Biwu | Liu, Yongchun | Li, Junhua | Takekawa, Hideto | Liggio, John | Li, Shao-Meng | Jiang, Jingkun | Hao, Jiming | He, Hong
α-Pinene/NOx and α-pinene/HONO photooxidation experiments at varying humidity were conducted in smog chambers in the presence or absence of FeSO4 seed particles. FeSO4 seed particles decrease SOA mass as long as water was present on the seed particle surface, but FeSO4 seed particles have no decreasing effect on SOA under dryer conditions at 12% relative humidity (RH). The decreasing effect of FeSO4 seed particles on the SOA mass is proposed to be related to oxidation processes in the surface layer of water on the seed particles. Free radicals, including OH, can be formed from catalytic cycling of Fe2+ and Fe3+ in the aqueous phase. These radicals can react further with the organic products of α-pinene oxidation on the seed particles. The oxidation may lead to formation of smaller molecules which have higher saturation vapor pressures and favor repartitioning to the gas phase, and therefore, reduces SOA mass.
Показать больше [+] Меньше [-]Silver, zinc oxide and titanium dioxide nanoparticle ecotoxicity to bioluminescent Pseudomonas putida in laboratory medium and artificial wastewater Полный текст
2014
Mallevre, Florian | Fernandes, Teresa F. | Aspray, Thomas J.
Bacteria based ecotoxicology assessment of manufactured nanoparticles is largely restricted to Escherichia coli bioreporters in laboratory media. Here, toxicity effects of model OECD nanoparticles (Ag NM-300K, ZnO NM-110 and TiO2 NM-104) were assessed using the switch-off luminescent Pseudomonas putida BS566::luxCDABE bioreporter in Luria Bertani (LB) medium and artificial wastewater (AW). IC50 values ∼4 mg L−1, 100 mg L−1 and >200 mg L−1 at 1 h were observed in LB for Ag NM-300K, ZnO NM-110 and TiO2 NM-104, respectively. Similar results were obtained in AW for Ag NM-300K (IC50 ∼5 mg L−1) and TiO2 NM-104 (IC50 >200 mg L−1) whereas ZnO NM-110 was significantly higher (IC50 >200 mg L−1). Lower ZnO NM-110 toxicity in AW compared to LB was associated with differences in agglomeration status and dissolution rate. This work demonstrates the importance of nanoecotoxicological studies in environmentally relevant matrices.
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