细化搜索
结果 91-100 的 1,273
Sources of ambient volatile organic compounds and their contributions to photochemical ozone formation at a site in the Pearl River Delta, southern China
2011
Ling, Z.H. | Guo, H. | Cheng, H.R. | Yu, Y.F.
The Positive Matrix Factorization (PMF) receptor model and the Observation Based Model (OBM) were combined to analyze volatile organic compound (VOC) data collected at a suburban site (WQS) in the PRD region. The purposes are to estimate the VOC source apportionment and investigate the contributions of these sources and species of these sources to the O₃ formation in PRD. Ten VOC sources were identified. We further applied the PMF-extracted concentrations of these 10 sources into the OBM and found "solvent usage 1", "diesel vehicular emissions" and "biomass/biofuel burning" contributed most to the O₃ formation at WQS. Among these three sources, higher Relative Incremental Reactivity (RIR)-weighted values of ethene, toluene and m/p-xylene indicated that they were mainly responsible for local O₃ formation in the region. Sensitivity analysis revealed that the sources of "diesel vehicular emissions", "biomass/biofuel burning" and "solvent usage 1" had low uncertainties whereas "gasoline evaporation" showed the highest uncertainty.
显示更多 [+] 显示较少 [-]Patterns of insect communities along a stress gradient following decommissioning of a Cu–Ni smelter
2011
Babin-Fenske, Jennifer | Anand, Madhur
The diversity, estimated richness and abundance of terrestrial insect communities were examined along a stress gradient of past pollution in the region of Sudbury, Ontario, Canada. This gradient represents the natural recovery and lingering effects of a decommissioned copper–nickel smelting complex. Ant genera and sixteen higher taxonomic groups (family and order) had the highest abundance at the sites with intermediate stress. Eight families increased in abundance with distance from the decommissioned source of pollution and eleven families decreased reflecting a complex response of diversity to pollution. Carabid beetles show an increase in diversity further from the smelter; however, examination of the species composition reveals a distinct carabid community closest to the smelter, emphasizing the unique habitat created by severe pollution. Although almost forty years since decomissioning of the smelter complex, the terrestrial insect community in the vicinity remains significantly impacted suggesting slow recovery.
显示更多 [+] 显示较少 [-]Variations in concentrations and compositions of polycyclic aromatic hydrocarbons (PAHs) in coals related to the coal rank and origin
2011
Laumann, S. | Micić, V. | Kruge, M.A. | Achten, C. | Sachsenhofer, R.F. | Schwarzbauer, J. | Hofmann, T.
The release of unburnt coal particles and associated polycyclic aromatic hydrocarbons (PAHs) may cause adverse impacts on the environment. This study assessed variations in the concentration and composition of PAHs in a set of fifty coal samples from eleven coal basins worldwide. The maximum PAH concentrations at high volatile bituminous rank were recorded in samples from a single basin. Considering the entire sample set, the highest PAH concentrations were in fact found outside of this rank range, suggesting that the maceral composition and thus the coal’s origin also influenced PAH concentrations. The examination of the PAH compositions revealed that alkylated 2–3 ring PAHs remain dominant compounds irrespective of coal rank or origin. Multivariate analysis based on PAH and maceral content, bulk and maturity parameters allowed the recognition of seven groups with different rank and origin within the coal sample set.
显示更多 [+] 显示较少 [-]Assessing estrogenic activity in surface water and sediment of the Liao River system in northeast China using combined chemical and biological tools
2011
This paper investigated some selected estrogenic compounds (4-t-octylphenol: 4-t-OP; 4-nonylphenols: 4-NP; bisphenol-A: BPA; diethylstilbestrol: DES; estrone: E1; 17β-estradiol: E2; 17α-Ethinylestradiol: EE2; triclosan: TCS) and estrogenicity in the Liao River system using the combined chemical and in vitro yeast screen bioassay and assessed their ecological risks to aquatic organisms. The estrogenic compounds 4-t-OP, 4-NP, BPA, E1, E2 and TCS were detected in most of the samples, with their concentrations up to 52.1 2065.7, 755.6, 55.8, 7.4 and 81.3ng/L in water, and up to 8.6, 558.4, 33.8, 7.9, <LOQ and 33.9ng/g in sediment, respectively. However, DES and EE2 were not detected in the Liao River. The estrogen equivalents (EEQ) of the water and sediment samples were also measured by the bioassay. High estrogenic risks to aquatic organisms were found in the river sections of metropolitan areas and the lower reach of the river system.
显示更多 [+] 显示较少 [-]Monitoring anthropogenic sewage pollution on mangrove creeks in southern Mozambique: A test of Palaemon concinnus Dana, 1852 (Palaemonidae) as a biological indicator
2011
Penha-Lopes, Gil | Torres, Paulo | Cannicci, Stefano | Narciso, Luís Filipe Castanheira | Paula, Jose
Tropical coastal ecosystems, such as mangroves, have a great ecological and socioeconomic importance for adjacent systems and local populations, but intensive environmental impact monitoring is still lacking, mainly in East Africa. This study evaluated the potential anthropogenic disturbance on Palaemon concinnus population structure and fitness. Palaemon concinnus populations from one peri-urban (domestic sewage impacted) and two pristine mangrove creeks were studied by sampling nearly 100 shrimps per location every 15 days for 12 months. The shrimps at the peri-urban location were larger, experienced longer reproductive periods, presented higher proportion of ovigerous females and better embryo quality when compared with shrimps inhabiting pristine locations. Physiological indices (RNA/DNA ratio) were similar between shrimps at pristine and peri-urban mangroves. However, a higher level of parasitation by a Bopyridae isopod, Pseudione elongata indicated some degree of stress on the host at the peri-urban mangrove, with potential effects on the host population dynamics.
显示更多 [+] 显示较少 [-]Zero-valent iron and iron oxide-coated sand as a combination for removal of co-present chromate and arsenate from groundwater with humic acid
2011
Mak, Mark S.H. | Rao, Pinhua | Lo, Irene M.C.
The combination of zero-valent iron (Fe⁰) and iron oxide-coated sand (IOCS) was used to remove Cr(VI) and As(V) from groundwater in this study. The efficiency and the removal mechanism of Cr(VI) and As(V) by using this combination, with the influence of humic acid (HA), were investigated using batch experiments. Results showed that, compared to using Fe⁰ or IOCS alone, the Fe⁰–IOCS can perform better on the removal of both Cr(VI) and As(V). Metal extraction studies showed that As(V) was mainly removed by IOCS and iron corrosion products while Cr(VI) was mainly removed by Fe⁰ and its corrosion products. Competition was found between Cr(VI) and As(V) for the adsorption sites on the iron corrosion products. HA had shown insignificant effects on Cr(VI) removal but some effects on As(V) removal kinetics. As(V) was adsorbed on IOCS at the earlier stage, but adsorbed/coprecipitated with the iron corrosion products at the later stage.
显示更多 [+] 显示较少 [-]Phytostabilization of semiarid soils residually contaminated with trace elements using by-products: Sustainability and risks
2011
Pérez-de-Mora, Alfredo | Madejón, Paula | Burgos, Pilar | Cabrera, Francisco | Lepp, N. W. (Nicholas W.) | Madejón, Engracia
We investigated the efficiency of various by-products (sugarbeet lime, biosolid compost and leonardite), based on single or repeated applications to field plots, on the establishment of a vegetation cover compatible with a stabilization strategy on a multi-element (As, Cd, Cu, Pb and Zn) contaminated soil 4–6 years after initial amendment applications. Results indicate that the need for re-treatment is amendment- and element-dependent; in some cases, a single application may reduce trace element concentrations in above-ground biomass and enhance the establishment of a healthy vegetation cover. Amendment performance as evaluated by % cover, biomass and number of colonizing taxa differs; however, changes in plant community composition are not necessarily amendment-specific. Although the translocation of trace elements to the plant biotic compartment is greater in re-vegetated areas, overall loss of trace elements due to soil erosion and plant uptake is usually smaller compared to that in bare soil.
显示更多 [+] 显示较少 [-]The use of environmental metabolomics to determine glyphosate level of exposure in rapeseed (Brassica napus L.) seedlings
2011
Petersen, Iben Lykke | Tomasi, Giorgio | Sørensen, H. (Hilmer) | Boll, Esther S. | Hansen, Hans Christian Bruun | Christensen, Jan H.
Metabolic profiling in plants can be used to differentiate between treatments and to search for biomarkers for exposure. A methodology for processing Ultra-High-Performance Liquid Chromatography–Diode-Array-Detection data is devised. This methodology includes a scheme for selecting informative wavelengths, baseline removal, retention time alignment, selection of relevant retention times, and principal component analysis (PCA). Plant crude extracts from rapeseed seedling exposed to sublethal concentrations of glyphosate are used as a study case. Through this approach, plants exposed to concentrations down to 5 μM could be distinguished from the controls. The compounds responsible for this differentiation were partially identified and were different from those specific for high exposure samples, which suggests that two different responses to glyphosate are elicited in rapeseed depending on the level of exposure. The PCA loadings indicate that a combination of other metabolites could be more sensitive than the response of shikimate to detect glyphosate exposure.
显示更多 [+] 显示较少 [-]Analysis of the ability of water resources to reduce the urban heat island in the Tokyo megalopolis
2011
Nakayama, Tadanobu | Hashimoto, Shizuka
Simulation procedure integrated with multi-scale in horizontally regional–urban-point levels and in vertically atmosphere–surface–unsaturated–saturated layers, was newly developed in order to predict the effect of urban geometry and anthropogenic exhaustion on the hydrothermal changes in the atmospheric/land and the interfacial areas of the Japanese megalopolis. The simulated results suggested that the latent heat flux in new water-holding pavement (consisting of porous asphalt and water-holding filler made of steel by-products based on silica compound) has a strong impact on hydrologic cycle and cooling temperature in comparison with the observed heat budget. We evaluated the relationship between the effect of groundwater use as a heat sink to tackle the heat island and the effect of infiltration on the water cycle in the urban area. The result indicates that effective management of water resources would be powerful for ameliorating the heat island and recovering sound hydrologic cycle there.
显示更多 [+] 显示较少 [-]Root porosity and radial oxygen loss related to arsenic tolerance and uptake in wetland plants
2011
Li, H. | Ye, Z.H. | Wei, Z.J. | Wong, M.H.
The rates of radial oxygen loss (ROL), root porosity, concentrations of arsenic (As), iron (Fe) and manganese (Mn) in shoot and root tissues and on root surfaces, As tolerances, and their relationships in different wetland plants were investigated based on a hydroponic experiment (control, 0.8, 1.6mg AsL⁻¹) and a soil pot trail (control, 60mg Askg⁻¹). The results revealed that wetland plants showed great differences in root porosity (9–64%), rates of ROL (55–1750mmo1 O₂kg⁻¹ root d.w.d⁻¹), As uptake (e.g., 8.8–151mgkg⁻¹ in shoots in 0.8mg AsL⁻¹ treatment), translocation factor (2.1–47% in 0.8mg AsL⁻¹) and tolerance (29–106% in 0.8mg AsL⁻¹). Wetland plants with higher rates of ROL and root porosity tended to form more Fe/Mn plaque, possess higher As tolerance, higher concentrations of As on root surfaces and a lower As translocation factor so decreasing As toxicity.
显示更多 [+] 显示较少 [-]