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Resultados 211-220 de 1,552
Environmental policy, legislation and management of persistent organic pollutants (POPs) in China Texto completo
2012
Lau, Melody Hoi Yin | Leung, Kenneth Mei Yee | Wong, Stella Wing Yu | Wang, Hong | Yan, Zhen-Guang
Since early 1980s, chemical pollution has become a serious environmental problem in rapidly developing China. This study reviewed the policy and legal framework for monitoring and management of chemical pollutants in China, with reference to the relevant experience in other jurisdictions. Although efforts in environmental monitoring of chemical contamination have been substantially increased over the last decade, China is lagging behind in terms of nationwide monitoring of chemical contamination in human population, and standardization of sampling and analytical protocols. While actively participating in various international treaties and conventions related to pollution control, China also has a very comprehensive set of environmental laws and policies. These include the newly enacted legislation on the control of new chemicals (i.e., China REACH) and the development of a set of National Environmental Standards. In addition to environmental education, these new measures will further enhance the control of chemical pollutants and facilitate effective law enforcement.
Mostrar más [+] Menos [-]Vegetative cover and PAHs accumulation in soils of urban green space Texto completo
2012
Peng, Chi | Ouyang, Z. (Zhiyun) | Wang, Meie | Chen, Weiping | Jiao, Wentao
We investigated how urban land uses influence soil accumulation of polycyclic aromatic hydrocarbons (PAHs) in the urban green spaces composed of different vegetative cover. How did soil properties, urbanization history, and population density affect the outcomes were also considered. Soils examined were obtained at 97 green spaces inside the Beijing metropolis. PAH contents of the soils were influenced most significantly by their proximity to point source of industries such as the coal combustion installations. Beyond the influence circle of industrial emissions, land use classifications had no significant effect on the extent of PAH accumulation in soils. Instead, the nature of vegetative covers affected PAH contents of the soils. Tree–shrub–herb and woodland settings trapped more airborne PAH and soils under these vegetative patterns accumulated more PAHs than those of the grassland. Urbanization history, population density and soil properties had no apparent impact on PAHs accumulations in soils of urban green space.
Mostrar más [+] Menos [-]Soil invertebrates as bioindicators of urban soil quality Texto completo
2012
Santorufo, Lucia | Van Gestel, Cornelis A.M. | Rocco, Annamaria | Maisto, Giulia
This study aimed at relating the abundance and diversity of invertebrate communities of urban soils to chemical and physical soil characteristics and to identify the taxa most sensitive or tolerant to soil stressors. The invertebrate community of five urban soils in Naples, Italy, was sampled. To assess soil quality invertebrate community indices (Shannon, Simpson, Menhinick and Pielou indices), Acarina/Collembola ratios, and the soil biological quality index (QBS) were calculated. The chemical and physical characteristics of the soils strongly differed. Abundance rather than taxa richness of invertebrates were more affected by soil characteristics. The community was more abundant and diverse in the soils with high organic matter and water content and low metal (Cu, Pb, Zn) concentrations. The taxa more resistant to the urban environment included Acarina, Enchytraeids, Collembola and Nematoda. Collembolans appeared particularly sensitive to changing soil properties. Among the investigated indices, QBS seems most appropriate for soil quality assessment.
Mostrar más [+] Menos [-]Building materials. VOC emissions, diffusion behaviour and implications from their use Texto completo
2012
Katsoyiannis, Athanasios | Leva, Paolo | Barrero-Moreno, Josefa | Kotzias, Dimitrios
Five cement- and five lime-based building materials were examined in an environmental chamber for their emissions of Volatile Organic Compounds (VOCs). Typical VOCs were below detection limits, whereas not routinely analysed VOCs, like neopentyl glycol (NPG), dominated the cement-based products emissions, where, after 72 h, it was found to occur, in levels as high as 1400 μg m⁻³, accounting for up to 93% of total VOCs. The concentrations of NPG were not considerably changed between the 24 and 72 h of sampling. The permeability of building materials was assessed through experiments with a dual environmental chamber; it was shown that building materials facilitate the diffusion of chemicals through their pores, reaching equilibrium relatively fast (6 h).
Mostrar más [+] Menos [-]Distribution of PCBs and PBDEs in soils along the altitudinal gradients of Balang Mountain, the east edge of the Tibetan Plateau Texto completo
2012
Zheng, Xiaoyan | Liu, Xiande | Jiang, Guibin | Wang, Yawei | Zhang, Qinghua | Cai, Yaqi | Cong, Zhiyuan
Surface soils were collected in Balang Mountain to explore the environmental process of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) during air transport. The average concentrations of ∑₂₅PCBs and ∑₁₃PBDEs in soils were 163 pg/g and 26 pg/g, respectively. The significant correlations between the concentrations of pollutants and total organic carbon (TOC) indicated the importance of TOC in accumulation potential of POPs. The slopes from fitted curves of PCBs were highly related with logKₒₐ, demonstrating that TOC dominates the soil-air exchange of PCBs. The TOC-normalized concentrations of contaminants in samples from below-treeline were higher than those from alpine meadow, probably due to the forest filter effect. The increasing trends of the concentrations with altitude from the alpine meadow samples, could be attributed to the mountain cold-trapping effect. And the weak cold-trapping effect of POPs might be due to the less precipitation in 2008 when comparing with those in 2006.
Mostrar más [+] Menos [-]Sorption kinetics of ofloxacin in soils and mineral particles Texto completo
2012
Pan, Bo | Wang, Peng | Wu, Min | Li, Jing | Zhang, Di | Xiao, Di
The environmental behavior of antibiotics is not well known and the precise environmental risk assessment is not practical. This study investigated the sorption kinetics of ofloxacin, a widely used antibiotics, on soil particles with different organic carbon contents as well as soil components (a humic acid, ferric oxide and kaolinite). Two-compartment sorption kinetics were mathematically recognized (except ferric oxide because of its very fast sorption). The apparent sorption rate and the contribution of fast sorption compartment decreased with the increased organic carbon content with the exception of humic acid, suggesting that the slow sorption sites were partially located in organo-mineral complex. The OFL concentration-dependent sorption kinetics suggested that the slow sorption compartment was not controlled by diffusion process as indicated by slower sorption at higher OFL loading. The difference between OFL sorption kinetics and those of hydrophobic organic contaminants was discussed and possible mechanism of OFL two-compartment sorption was proposed.
Mostrar más [+] Menos [-]Ozone visible symptoms and reduced root biomass in the subalpine species Pinus uncinata after two years of free-air ozone fumigation Texto completo
2012
Díaz-de-Quijano, Maria | Schaub, Marcus | Bassin, Seraina | Volk, Matthias | Peñuelas, Josep
Concentrations of ozone often exceed the thresholds of forest protection in the Pyrenees, but the effect of ozone on Pinus uncinata, the dominant species in subalpine forests in this mountainous range, has not yet been studied. We conducted an experiment of free-air ozone fumigation with saplings of P. uncinata fumigated with ambient O₃ (AOT40 May–Oct: 9.2 ppm h), 1.5 × O₃ₐₘb (AOT40 May–Oct: 19.2 ppm h), and 1.8 × O₃ₐₘb (AOT40 May–Oct: 32.5 ppm h) during two growing seasons. We measured chlorophyll content and fluorescence, visible injury, gas exchange, and above- and below-ground biomass. Increased exposures to ozone led to a higher occurrence and intensity of visible injury from O₃ and a 24–29% reduction of root biomass, which may render trees more susceptible to other stresses such as drought. P. uncinata is thus a species sensitive to O₃, concentrations of which in the Pyrenees are already likely affecting this species.
Mostrar más [+] Menos [-]Ozone deposition to an orange orchard: Partitioning between stomatal and non-stomatal sinks Texto completo
2012
Fares, Silvano | Weber, Robin | Park, Jeong-Hoo | Gentner, Drew | Karlik, Jan | Goldstein, Allen H.
Orange trees are widely cultivated in regions with high concentrations of tropospheric ozone. Citrus absorb ozone through their stomata and emit volatile organic compounds (VOC), which, together with soil emissions of NO, contribute to non-stomatal ozone removal. In a Valencia orange orchard in Exeter, California, we used fast sensors and eddy covariance to characterize water and ozone fluxes. We also measured meteorological parameters necessary to model other important sinks of ozone deposition. We present changes in magnitude of these ozone deposition sinks over the year in response to environmental parameters. Within the plant canopy, the orchard constitutes a sink for ozone, with non-stomatal ozone deposition larger than stomatal uptake. In particular, soil deposition and reactions between ozone, VOC and NO represented the major sinks of ozone. This research aims to help the development of metrics for ozone-risk assessment and advance our understanding of citrus in biosphere-atmosphere exchange.
Mostrar más [+] Menos [-]Class 1 and 2 integrons, sul resistance genes and antibiotic resistance in Escherichia coli isolated from Dongjiang River, South China Texto completo
2012
Su, Hao-Chang | Ying, Guang-Guo | Tao, Ran | Zhang, Rui-Quan | Zhao, Jian-Liang | Liu, You-Sheng
Antibiotic susceptibility, detection of sul gene types and presence of class 1, 2 and 3 integrons and gene cassettes using PCR assays were investigated in 3456 Escherichia coli isolates obtained from 38 sampling sites of the Dongjiang River catchment in the dry and wet seasons. 89.1% of the isolates were resistant and 87.5% showed resistance to at least three antibiotics. sul2 was detected most frequently in 89.2% of 1403 SXT-resistant isolates. The presence of integrons (class 1 and 2) was frequently observed (82.3%) while no class 3 integron was found. In these integrons, 21 resistance genes of 14 gene cassette arrays and 10 different families of resistance genes were identified. Three gene cassette arrays, aac(6')-Ib-cr-aar-3-dfrA27-aadA16, aacA4-catB3-dfrA1 and aadA2-lnuF, were detected for the first time in surface water. The results showed that bacterial resistance in the catchment was seriously influenced by human activities, especially discharge of wastewater.
Mostrar más [+] Menos [-]Legacy and current-use flame retardants in house dust from Vancouver, Canada Texto completo
2012
Shoeib, Mahiba | Harner, Tom | Webster, Glenys M. | Sverko, Ed | Cheng, Yu
Fifteen polybrominated diphenyl ethers (PBDEs) and eighteen non-PBDEs were measured in 116 dust samples collected from homes in Vancouver, Canada during 2007–2008 as part of the Chemicals Health and Pregnancy (CHirP) study. The highest concentrations of PBDEs in house dust were observed for BDE 209, with a median concentration of 1350 ng/g. This is about two times greater than the median concentration of the PentaBDE (represented by the most abundant compounds in this formulation, ΣBDE 47, 99 and 100). In the case of non-PBDE FRs, a detection frequency between 81% and 100% was observed for nine analytes including: HBCD, BTBPE, BEHTBP, EHTBB, HBB, PBTO, PBBe, ATE and DP. The high detection of new FRs in indoor environments reflects their ubiquitous presence in indoor environment due to regulation of the PBDEs. Exposure to FRs are estimated based on these data for adults and toddlers.
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