Уточнить поиск
Результаты 31-40 из 147
The ecology of transportation
2006
Davenport, J. (John) | Davenport, Julia L.
Human transport by land, sea and air has increased exponentially through time in intensity, paralleling rises in population, prosperity and rates of technological change. Transport has considerable ecological effects, many of them detrimental to environmental sustainability. This volume brings together international experts from a variety of disciplines to review the ecological effects and their causes in terms of road, rail, ship and aircraft transport. The contributors have different attitudes and agendas. Some are ecologists, some planners, others social scientists. Focus ranges from identification of threats and amelioration of damaging effects through to future design of transport systems to minimize environmental degradation. Some chapters consider restricted areas of the globe; others the globe itself. Views encompass deep pessimism and cautious optimism. Uniquely, the volume considers transport effects in all environments. This is the first book that attempts to discuss the relationship between human transport and all ecosystems. It appeals not only to the specialist environmentalist by picking out novel topics, but also to anyone involved in transport issues as it tackles the issues from an historical perspective, encompassing the past, present and future of the effects of human transport.
Показать больше [+] Меньше [-]The Fernow watershed acidification study
2006
Adams, Mary Beth | DeWalle, David R. | Hom, John Lun
Focus on water pollution research
2006
Livingston, James V.
Biochemical Cooperation Between Klebsiella oxytoca Sc and Methylobacterium mesophilium Sr for Complete Degradation of Dimethyl Isophthalate
2006
Li, Jiaxi | Gu, J.-D.
Klebsiella oxytoca Sc and Methylobacterium mesophilicum Sr were isolated from enrichment cultures using dimethyl isophthalate (DMI) as the sole carbon and energy source and mangrove sediment as an inoculum. Complete degradation of DMI required both species of bacteria at different biochemical transformation steps. The biochemical degradation pathway was DMI to monomethyl isophthalate (MMI) by K. oxytoca Sc, MMI to isophthalate (IPA) by M. mesophilium Sr, and IPA by both K. oxytoca Sc and M. mesophilium Sr sequentially. The consortium comprising of K. oxytoca Sc and M. mesophilicum Sr was effective in complete degradation of DMI in eight days. Our results suggest that a consortium of microorganisms indigenous to the mangrove environment is responsible for mineralization of environmental pollutant DMI through biochemical cooperation.
Показать больше [+] Меньше [-]The Effect of Sediment Source Changes on Pollen Records in Lake Sediments
2006
Pittam, N. J | Mighall, T. M | Foster, I. D. L
A major focus of palynological research has been to assess the various pathways by which pollen is delivered to sedimentary archives. In open lake systems, the contribution of streamborne pollen to lake sediments is thought to be highly significant. Despite this, little research has attempted to identify changes in the pollen record that might be attributed to changing sediment pathways rather than to changes in vegetation. This research aims to partially redress this gap by examining a dated pollen sequence from Kyre Pool, Worcestershire, England. The results presented in this paper suggest that some changes in sediment source, as determined by a fingerprinting approach, can influence the pollen record reconstructed from a lake sediment profile.
Показать больше [+] Меньше [-]Changes in Extractability of Cr and Pb in a Polycontaminated Soil After Bioaugmentation With Microbial Producers of Biosurfactants, Organic Acids and Siderophores
2006
Braud, Armelle | Jézéquel, Karine | Vieille, Emilie | Tritter, Adrien | Lebeau, Thierry
Partly because of the low bioavailability of metals, the soil cleaning-up using phytoremediation is usually time-consuming. In order to enhance the amount of metals at the plant's disposal, the soil bioaugmentation coupled together with phytoextraction is an emerging technology. In this preliminary work, two agricultural soils which mainly differed in their Cr, Hg and Pb contents (LC, low-contaminated soil; HC, high-contaminated soil) were bioaugmented in laboratory conditions by either bacterial (Bacillus subtilis, Pseudomonas aeruginosa, Pseudomonas fluorescens or Ralstonia metallidurans) or fungal inocula (Aspergillus niger or Penicillium simplicissimum) and incubated during three weeks. The LC soil pots bioaugmented with A. niger and P. aeruginosa contained higher concentrations of Cr (0.08 and 0.25 mg.kg-¹ dw soil) and Pb (0.25 and 0.3 mg.kg-¹ dw soil) in the exchangeable fraction F1 (extraction with MgCl₂) by comparison with the non-bioaugmented soil where neither Cr nor Pb was detected. Conversely, immobilization of Cr and Pb in the soil were observed with the other microorganisms. The soil bioaugmentation not only modified the metal speciation for the most easily extractable fractions but also modified the distribution of metals in the other fractions, to a lesser extent nevertheless. The difference in microbial concentrations between the bioaugmented or not HC soils reached up to 1.8 log units. Thus the microorganisms that we chose for the soil bioaugmentation were competitive towards the indigenous microflora. The PCA analysis showed close positive relationships between the microorganisms which potentially produced siderophores in the soil and the amount of Cr and Pb in the fraction F1.
Показать больше [+] Меньше [-]SedTrap: A Conceptual Model for Trap Efficiencies in a Sedimentation Basin
2006
Warner, Glenn S
Sedimentation basins and sediment traps are established methodologies for reducing sediment and other pollutants exiting small watersheds such as urban areas and construction sites. However, estimating the trap efficiency or designing a basin or trap to provide a pre-determined trap efficiency, is difficult, especially for dynamic conditions of water and sediment inflow. A conceptual dynamic model, called SedTrap, was developed that can be used to assess the varying removal efficiencies as a storm is routed through different sized basins or traps. The model uses the STELLA® modeling software from Iseesystems, Inc. to build a dynamic model to route both water and sediment through the system. Settling velocities are determined for a range of sediment sizes and temperatures using the Rubey-Watson law and compared to the more traditional Stokes' law. The variation of efficiencies with time and by sediment size as the basin fills with sediment is also addressed. The results for the example used show a decrease in trap efficiencies with decreasing particle size, which leads to an increase in percent fine material of total sediment load at the outlet of the basin. This “fining” of the material coupled with the higher surface area per mass of the fine particles has implications for changes in the upstream-downstream concentrations of adsorbed contaminants.
Показать больше [+] Меньше [-]Direct and Indirect Effects of Soil Pollution by Lignite Mining
2006
Schaaf, Wolfgang | Hüttl, R. F.
Lignite mining and processing has caused a pronounced impact both directly and indirectly on soils and ecosystems across large areas of the former GDR. We studied soils of pine forest ecosystems at sites affected by severe alkaline dust and sulphur deposition, stemming from lignite fired power plant emission, and at dumped sites from lignite mining. In this paper we summarize our main results and evaluate the long-term impact of lignite mining and combustion on the environment. The pine ecosystems on naturally developed soils show a clear effect of deposition history along a former deposition gradient with distinct changes in chemical properties of organic surface layers and mineral soil as well as in element turnover and cycling rates. Afforested sites on mining dumps are directly affected by the composition of the dumped substrates. Over a large area (800 km²) these substrates are dominated by Tertiary sediments with varying amounts of lignitic particles and pyrite that result in phytotoxic site conditions (pH < 3, high salt and metal contents). High amelioration doses of liming material (up to 200 t ha-¹) were applied for restoration purposes. We studied the development of these sites over a period of 60 years using a false-time series approach. Beside the extreme soil conditions, element budgets of these sites are characterized by very high element release rates over decades caused by pyrite oxidation and primary mineral weathering.
Показать больше [+] Меньше [-]Chromium Removal from Soil by Phytoremediation with Weed Plant Species in Thailand
2006
Sampanpanish, Pantawat | Pongsapich, Wasant | Khaodhiar, Sutha | Khan, Eakalak
The possibility of using phytoremediation with weed plant species in Thailand to remove chromium (Cr) from soil was investigated. Six plant species, Cynodon dactylon, Pluchea indica, Phyllanthus reticulatus, Echinochloa colonum, Vetiveria nemoralis, and Amaranthus viridis, were chosen for their abilities to accumulate total chromium (TCr) at tanning industry sites. These plant species were studied in pots at a nursery. Cynodon dactylon and Pluchea indica provided highest TCr accumulation capacities of 152.1 and 151.8 mg/kg of plant on a dry weight basis, respectively, at a pulse hexavalent Cr [Cr(VI)] input of 100 mg Cr(VI)/kg soil. Most of the Cr uptake occurred within 30 days after the input. The TCr accumulation by Pluchea indica was observed in roots, stems, and leaves at 27%, 38%, and 35% of the TCr mass uptake, respectively, whereas 51%, 49% and 0% of the TCr mass uptake accumulated in roots, stems, and leaves of Cynodon dactylon, respectively. The results on Cr accumulation and translocation in plant tissues suggest that Cr was removed mainly via phytoaccumulation and Pluchea indica is more suitable than Cynodon dactylon for the phytoremediation of Cr contaminated soil.
Показать больше [+] Меньше [-]Fate and behavior of metal(loid) contaminants in an organic matter-rich shooting range soil: Implications for remediation
2006
Dermatas, Dimitris | Cao, Xinde | Tsaneva, Valentina | Shen, Gang | Grubb, Dennis G
This study investigates the fate and behavior of lead (Pb), copper (Cu), antimony (Sb), and arsenic (As) in a shooting range soil. The soil samples were collected from the surface (0-15 cm) and the subsurface (15-40 cm and 40-55 cm) of a grassy and wood chip covered impact area behind a firing position. Optical microscopy images indicate significant amounts of corroded bullet fragments and organic wood chips in the surface soil. Analysis by X-ray powder diffraction (XRPD) and scanning electron microscopy electron dispersive X-ray spectroscopy (SEM-EDS) showed that metallic Pb was transformed into lead oxides (litharge PbO and massicot PbO) and lead carbonates (hydrocerussite Pb₃(CO₃)₂(OH)₂, cerussite PbCO₃, and plumbonacrite Pb₅(CO₃)₃O(OH)₂). Rietveld quantification indicated the surface soil contained 14.1% metallic Pb, 17.9% hydrocerussite, 5.2% plumbonacrite, 5.9% litharge, and 3.9% massicot on a dry weight basis, or a total of 39.7% Pb, far in excess of lead concentrations typically found in US shooting range soils. Metallic Cu (bullet jacket material) appeared stable as no secondary minerals were detected in the surface soil. As and Sb concentrations were on the order of 1,057 mg/kg and 845 mg/kg respectively. The elevated soil pH coupled with high organic carbon content is thought to have caused downward migration of metals, especially for Pb, since 4,153 mg Pb/kg was observed at a depth of 55 cm. More than 60% of Pb was concentrated in the coarse soil (> 0.425 mm) fraction, suggesting soil clean-up possible by physical soil washing may be viable. The concentrations of Pb, As, and Sb in the toxicity characteristic leaching procedure (TCLP) extracts were 8,869 mg/L, 6.72 mg/L, and 6.42 mg/L respectively, were above the USEPA non-hazardous regulatory limit (As and Pb) of 5 mg/L. The elevated Sb and As concentrations draw concern because there is historically limited information concerning these metals at firing ranges and several values exceeded local soil cleanup criteria. As the high Pb concentrations appeared to be linked to the presence of organic-rich berm cover materials, the use of wood chips as berm cover to prevent soil erosion requires reconsideration as a shooting range management practice.
Показать больше [+] Меньше [-]