细化搜索
结果 941-950 的 1,324
Microbially Mediated Degradation of Common Pharmaceuticals and Personal Care Products in Soil Under Aerobic and Reduced Oxygen Conditions 全文
2011
Carr, Deborah L. | Morse, Audra N. | Zak, John C. | Anderson, Todd A.
Biological degradation rates of estrogen compounds and common pharmaceutical and personal care products (PPCPs) were examined in soils with a long history of exposure to these compounds through wastewater effluent and in soil not previously exposed. Biological degradation rates over 14 days were compared under aerobic and anaerobic conditions. Estrogen compounds including estrone, 17β-estradiol, estriol, and 17α-ethinylestradiol exhibited rapid degradation by soil microorganisms in both aerobic and anaerobic conditions. Rapid degradation rates for estrone, estriol, and 17α-ethinylestradiol occurred in pre-exposed soil under aerobic conditions; half-lives calculated under these conditions were 0.6, 0.7, and 0.8 day, respectively. Unexposed soil showed similar or slightly longer half-lives than pre-exposed soil under aerobic conditions. The exception was 17β-estradiol; in all treatments, degradation in unexposed soil resulted in a shorter half-life (2.1 versus 2.3 days). Anaerobic soils exhibited high biological degradation of estrogens as well. Half-lives of all estrogens ranged from 0.7 to 6.3 days in anaerobic soils. Triclosan degraded faster under aerobic conditions with half-lives of 5.9 and 8.9 days in exposed and unexposed soil. Under anaerobic conditions, triclosan half-lives were 15.3 days in unexposed and 28.8 days in exposed soil. Ibuprofen showed the least propensity toward biological degradation than other chemicals tested. Biological degradation of ibuprofen was only observed in unexposed soil; a half-life of 41.2 days was determined under anaerobic conditions and 121.9 days under aerobic conditions. Interestingly, unexposed soil exhibited a greater ability under anaerobic conditions to biologically degrade tested compounds than previously exposed soil.
显示更多 [+] 显示较少 [-]A Review on Ozone Evolution and Its Relationship with Boundary Layer Characteristics in Urban Environments 全文
2011
Tong, Nelson Y. O. | Leung, Dennis Y. C. | Liu, Chun-Ho
This paper reviews the interrelationship among boundary layer, urbanization, and evolution of ozone, with particular emphasis on how boundary layer dynamics and urbanization affects the evolution of ozone under different meteorological and climatological conditions. The aim of this work is not only to provide an exhaustive investigation of individual ozone episodes but to look at the underlying issues and hypotheses that are available for understanding the evolution of ozone. The review concludes with a summary of the current state of knowledge and outlines some of the remaining questions. It is the intention of this paper to serve as an ecumenical reference to the community for reappraising the relation of boundary layer climate to the evolution of ozone in an urban setting, especially on a peculiar feature of ozone dynamic, nocturnal ozone maxima. To date, there is still no overarching consensus on the mechanisms that lead to its formation. The importance of levels of urbanization and advantage of ascertaining the substantial weights of the respective mixing height and emission structure in exploring the relationship between ozone evolutions should not be overlooked.
显示更多 [+] 显示较少 [-]Invertebrates Minimize Accumulation of Metals and Metalloids in Contaminated Environments 全文
2011
Schaller, Joerg | Brackhage, Carsten | Dudel, E Gert
Many studies were conducted measuring the lethal concentration of pollutants by using a contaminated solution or polluted sediments. Considering the impact of polluted food on mortality and uptake quantity of invertebrate shredders in batch cultures, little is known about, e.g. uranium and cadmium. Consequently, we investigated in situ the impact of metal and metalloid polluted food and water on Gammarus pulex L. under nature-like conditions. In contrast to other publications, a very low mortality rate of the invertebrates was found. Furthermore, fixation of elements by G. pulex was shown to be low compared to initial concentrations. Fixation of non essential metals and metalloids is shown to take place mainly on the surface of the invertebrates. This is deduced from easy desorption of a relevant amount of fixed metals and metalloids. It is concluded that the accumulation of metals and metalloids in situ under nature-like conditions within the food web via invertebrate shredders is very low. The invertebrates seem to minimize the uptake of non essential elements in the presence of nutrient-rich food even in habitats with higher contamination levels. Hence, invertebrates seem to be adapted to higher contamination levels in their favourable habitats.
显示更多 [+] 显示较少 [-]Influence of Catchment Characteristics and Flood Type on Relationship Between Streamwater Chemistry and Streamflow: Case Study from Carpathian Foothills in Poland 全文
2011
Siwek, Joanna P. | Żelazny, Mirosław | Chełmicki, Wojciech
The study aimed to determine the influence of catchment characteristics and flood type on the relationship between streamflow and a number of chemical characteristics of streamwater. These were specific electrical conductivity (SC), pH, the concentrations of main ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO ₃ ⁻ , SO ₄ ²⁻ , and Cl⁻), and nutrients (NH ₄ ⁺ , NO ₂ ⁻ , NO ₃ ⁻ , and PO ₄ ³⁻ ). These relationships were studied in three small catchments with different geological structure and land use. Several flood types were distinguished based on the factors that initiate flooding and specific conditions during events. Geological factors led to a lower SC and main ion concentrations at a given specific runoff in catchments built of resistant sandstone versus those built of less resistant sediments. A lower concentration of nutrients was detected in the semi-natural woodland catchment versus agricultural and mixed-use catchments, which are strongly impacted by human activity. The strongest correlation between streamflow and the chemical characteristics of water was found in the woodland catchment. Different types of floods were characterized by different ion concentrations. In the woodland catchment, higher SC and higher concentrations of most main ions were noted during storm-induced floods than during floods induced by prolonged rainfall. The opposite was true for the agricultural and mixed-use catchments. During snowmelt floods, SC, NO ₃ ⁻ , and most main ion concentrations were higher when the soil was unfrozen in the agricultural and mixed-use catchments versus when the soil was frozen. In the case of the remaining nutrients, lower concentrations of NH ₄ ⁺ were detected during rain-induced floods than during snowmelt floods. The opposite was true of PO ₄ ³⁻ .
显示更多 [+] 显示较少 [-]A Quantum Statistical Approach to Remediation Effect of Humic Substances 全文
2011
N. Aleksandrova, Olga | Schulz, Marcus | Matthies, Michael
Among various remediation factors, dissolved organic matter including humic substances (HS) has substantial effect on environmental contamination significantly changing the contaminant’s degradation, bioavailability, reactivity, and immobilization. However, the effects strongly depend on HS concentrations and their aromaticity index (AI). To understand underlying phenomena of remediation action of HS, which is revealed to occur within a definite interval of HS concentrations in water solution, a quantum statistical approach is supposed. Developing this approach, a model of protons as Fermi particles in humic substances was advanced for the first time and applied to describe transformations of HS molecules, i.e., multipoles into micelle structures, which in turn provide for mediating effects in water. Sufficiently high concentration of micelle granules in water solution exists if the concentration of HS lies within a definite interval. It was demonstrated applying a grand canonical Gibbs distribution method to a statistical ensemble of HS particles. Our approach allows for understanding and quantifying some biological and physiological processes connected with mediating action of HS, as for example the reversible red cell aggregation influenced by HS, adsorption of HS particles by cancer cells, and effect of HS on human resistibility to inflammatory processes of different kinds. Application of our results to water systems may be helpful to optimize waste processing and disposal.
显示更多 [+] 显示较少 [-]Wet and Dry Deposition Fluxes of Polychlorinated Biphenyls (PCBs) in an Urban Area of Turkey 全文
2011
Günindi, Manolya | Tasdemir, Yücel
Atmospheric polychlorinated bihenyls (PCBs) deposit by dry and wet deposition mechanisms, and therefore they constitute a significant polluting source for lands and surface waters. Various samplers have been used to determine the PCB pollution level resulting from deposition. In the presented study, a modified wet deposition sampler (WDS) was used for sampling both wet and dry deposition samples with the same instrument by which wet deposition reservoir of the WDS is opened and dry deposition reservoir is closed when rain starts. Wet and dry deposition samples were collected between June 2008 and June 2009. In the samples taken from BUTAL which is known as an urban area with heavy traffic, âPCB dry deposition fluxes were determined as 18â±â10 ng/m2â−day, and wet deposition fluxes for dissolved and particle phase were measured as 480â±â1,185 and 475â±â1,000 ng/m2â−day, respectively. The dissolved and particle-phase PCB concentrations in rain were 10â±â13 and 13â±â14 ng/l, respectively. The contribution of wet deposition to total PCB deposition was determined as 52%. PCB concentrations in the ambient air were measured to be 370â±â200 and 20â±â20 pg/m3 for gas and particle phases, respectively. Washout ratio was determined by proportioning rain concentration to concentration in air. The washout ratios of the samples were between 1,675–311,800 and 12,775–2,511,120 for dissolved and particulate phases, respectively.
显示更多 [+] 显示较少 [-]Stability of Fe- and Mn-(oxyhydr)oxides in Common Soil Dispersion Solutions 全文
2011
Manh, Phung N. | Ali Khan, Moonis | Jeon, Byong-Hun | Kim, Jae Gon | Lee, Giehyeon
Soil dispersion is a prerequisite process for the separation of metal oxides from bulk soil when magnetic separation is employed to enhance the efficiency for soil treatment. This study examined the stability of goethite, hematite, birnessite, and manganite in common dispersion solutions. The stability of pH in the oxide suspension decreased in the order carbonate (50Â mM Na2CO3) > pyrophosphate (50Â mM Na4P2O7) > simple alkaline (1Â mM NaOH) solutions regardless of the oxides. Dissolution of the four oxides was negligible in the carbonate and the simple alkaline solutions. In the pyrophosphate solutions, however, the oxides were subject to ligand-promoted dissolution by pyrophosphate ion. The extent of dissolution was highest for goethite followed by manganite, hematite, and birnessite. Dissolved Fe and Mn concentrations reached 68.3 and 4.1Â μM for goethite and manganite suspensions, respectively, in 21Â days with 5Â mM pyrophosphate. Higher pyrophosphate concentrations (up to 150Â mM) did not substantially affect the extent of ligand-promoted dissolution due to the limited surface sites of the oxides. The results of this study suggest that the carbonate solution would be more desirable than the simple alkaline or the pyrophosphate solution for soil dispersion in the presence of common Fe or Mn oxides.
显示更多 [+] 显示较少 [-]Study of Ni(II), Cu(II), Pb(II), and Zn(II) Removal Using Sludge and Minerals Followed by MF/UF 全文
2011
Malamis, Simos | Katsou, Evina | Haralambous, Katherine J.
This work examined the removal of heavy metals in a system consisting of ultrafiltration (UF) or microfiltration (MF) membranes combined with sludge and minerals. The metals under examination were Ni(II), Cu(II), Pb(II), and Zn(II), while the system performance was investigated with respect to several operating parameters. Metal removal was achieved through various processes including chemical precipitation, biosorption, adsorption, ion exchange, and finally retention of the metals by the membranes. The pH had a profound effect on metal removal, as the alkaline environment favored the metal removal process. The use of sludge resulted in increased levels of metal uptake which was further enhanced with the addition of minerals. The metal removal mechanisms depended on the pH, the metal, and mineral type. The combined sludge–mineral–UF system could effectively remove metal ions at an alkaline environment (pH = 8), meeting the US EPA recommended long-term reuse limits of lead and copper and the short-term reuse limits of nickel and zinc for irrigation purposes, provided that specific mineral dosages were added.
显示更多 [+] 显示较少 [-]Atmospheric Emission Inventory for Natural and Anthropogenic Sources and Spatial Emission Mapping for the Greater Athens Area 全文
2011
Aleksandropoulou, Victoria | Torseth, Kjetil | Lazaridis, M.
A spatially, temporally and chemically resolved emission inventory for particulate matter and gaseous species from anthropogenic and natural sources was created for the Greater Athens Area (GAA; base year, 2007). Anthropogenic sources considered in this study include combustion (industrial, non-industrial, commercial and residential), industrial production, transportation, agriculture, waste treatment and solvent use. The annual gaseous pollutants (ΝΟx, SOx, non-methane volatile organic compounds (NMVOCs), CO and ΝΗ3) and particulate matter (PM2.5 and PM2.5–10) emissions were derived from the UNECE/EMEP database for most source sectors (SNAP 1–9; 50 × 50 km2) and their spatial resolution was increased using surrogate spatial datasets (land cover, population density, location and emissions of large point sources, emission weighting factors for the GAA; 1 × 1 km2). The emissions were then temporally disaggregated in order to provide hourly emissions for atmospheric pollution modelling using monthly, daily and hourly disintegration coefficients, and additionally the chemical speciation of size-segregated particles and NMVOCs emissions was performed. Emissions from agriculture (SNAP 10) and natural emissions of particulate matter from the soil (by wind erosion) and the sea surface and of biogenic gaseous pollutants from vegetation were also estimated. During 2007 the anthropogenic emissions of CO, SOx, NOx, NMVOCs, NH3, PM2.5 and PM2.5–10 from the GAA were 151,150, 57,086, 68,008, 38,270, 2,219, 9,026 and 3,896 Mg, respectively. It was found that road transport was the major source for CO (73.3%), NMVOCs (31.6%) and NOx (35.3%) emissions in the area. Another important source for NOx emissions was other mobile sources and machinery (23.1%). Combustion for energy production and transformation industries was the major source for SOx (38.5%), industrial combustion for anthropogenic PM2.5–10 emissions (59.5%), whereas non-industrial combustion was the major source of PM2.5 emissions (49.6%). Agriculture was the primary NH3 source in the area (72.1%). Natural vegetation was found to be an important source of VOCs in the area which accounted for approximately the 5% of total VOCs emitted from GAA on a typical winter day. The contribution of sea-salt particles to the emissions of PM2.5 was rather small, whereas the emissions of resuspended dust particles exceeded by far the emissions of PM2.5 and PM2.5–10 from all anthropogenic sources.
显示更多 [+] 显示较少 [-]Influence of Airborne Pollution on Cd, Zn, Pb, Cu, and Al Accumulation and Physiological Parameters of Plant Leaves in Antakya (Turkey) 全文
2011
Doğanlar, Zeynep Banu | Atmaca, Mustafa
In this study, the effects of industrial and urban pollution on Pb, Al, Cd, Cu, and Zn accumulation, peroxidase activity, and pigment and protein contents were investigated in shrub and tree leaves in Antakya, Turkey. We determined that industrial and traffic activities produce the most plant-incorporated air pollutants in Antakya City. Cu and Al amounts were high in plants in the urban street location and Cd, Pb, and Zn amounts where high for all plants in the industrial site. Acer negundo L. showed maximum Pb and Zn accumulation at the industrial site and Al accumulation for the urban street site. Higher Cd and Cu amounts were detected in Platanus orientalis L. and Nerium oleander L. in the industrial and urban street sites, respectively. Compared to the control site, decreases in pigment and total soluble protein contents and increases in peroxidase enzyme activity were more evident in industrial and urban street sites. Our results indicated that industry and urban air pollution is high in Antakya City and Pb pollution was at an especially alarming level for vegetation and human health.
显示更多 [+] 显示较少 [-]