The role of household demographic factors in shaping transportation spending in Turkey

Environment, Development and Sustainability - Factors at the family scale, for which dynamic decisions and proper investments need to be made at the national level in curbing greenhouse gas...     

Biodegradation of phenanthrene in river sediment

The aerobic biodegradation potential of phenanthrene (a polycyclic aromatic hydrocarbon [PAH]) in river sediment was investigated in the laboratory. Biodegradation rate constants (k1) and half-lives (t1/2) for phenanthrene (5 microg/g) in sediment samples collected at five sites along the Keelung River in densely populated northern Taiwan ranged from 0.12 to 1.13 l/day and 0.61 to 5.78 day, respectively. Higher biodegradation rate constants were noted in the absence of sediment. Two of the sediment samples were capable of biodegrading phenanthrene at initial concentrations 5-100 microg/g; lower biodegradation rates occurred at higher concentrations. Optimal biodegradation conditions were determined as 30 degreesC and pH 7.0. Biodegradation was not significantly influenced by the addition of such carbon sources as acetate, pyruvate, and yeast extract, but was significantly influenced by the addition of ammonium, sulfate, and phosphate. Results show that anthracene, fluorene, and pyrene biodegradation was enhanced by the presence of phenanthrene, but that phenanthrene treatment did not induce benzo[a]pyrene biodegradation during a 12-day incubation period.     

Metal partitioning in river sediments measured by sequential extraction and biomimetic approaches

We quantified the concentrations and distributions of metals (Cd, Cr, Cu, Ni, Pb, and Zn) in the sediments of Tuen Mun River, Hong Kong. The potential bioavailability of metals was assessed with a biomimetic extraction method using the sipunculan gut juices. The sediments were characterized by relatively high concentrations of trace metals. Field collected sediments were highly anoxic and the ratio of simultaneously extractable metal (sigmaSEM) to acid volatile sulfide (AVS) was much less than one in these sediments. The majority (>67%) of Cd, Pb, and Zn were bound to AVS, thus their concentrations in the sediment porewater were low. In contrast, Ni was little bound to AVS due to its lower ratios of SEM-Ni to total Ni concentrations. For Cu, relatively high concentrations in the sediment porewater was found, and total organic carbon, AVS and other resistant sulfide phase were the controlling factors for sedimentary Cu partitioning. Net metal adsorption from gut juices to anoxic sediments was observed in metal extraction experiments, suggesting that AVS determined the bioaccumulation and potential bioavailability of most metals in these sediments. Extraction of metals from the oxidized sediments by the gut juices was mainly attributed to metal redistribution from AVS to other geochemical phases. The gut juices were the most effective solvent or extractant than the simple electrolyte solution [I (NaNO(3)) = 0.01 M] and the natural overlying water. Cd was more easily extracted from the oxidized sediments than Zn that tended to have a stronger binding affinity with Fe-Mn oxide, clay and organic matter. The application of partial removal techniques in metal extraction experiments further demonstrated the differential controls of various sediment geochemical phases in affecting metal bioavailability, with the order of TOC > Fe-Mn oxides > carbonate.     

The effect of aniline on photochemical reactions in atmospheric and synthetic air samples

The inhibitory effect of aniline in photochemical smog reactions was studied using actual Toronto air samples. An aniline concentration of 0.81 pphm had negligible effect in a light traffic air sample containing negligible NO, whereas 20 pphm in a heavy traffic sample caused a 70% decrease in the oxidant dosage, a 50% decrease in the NO₂ peak and a four-fold increase in the NO half-life. In experiments with propylene in synthetic mixtures, the half-life of propylene was increased from 144 min. to 192 min. by the present of 20 pphm of aniline. In addition, a thirty-fold increase in condensation nuclei was produced following a one hour induction period. A chemical mechanism is proposed which is consistent with these results. Although the condensation nuclei detected may be too small to produce light scattering, they may be retained in the lung. In addition they may grow in size. These consequences do not favour the use of aniline as an inhibitor in photochemical smog.     

CHANGES IN HYDROLOGIC RESPONSE DUE TO STREAM NETWORK EXTENSION VIA LAND DRAINAGE ACTIVITIES1

ABSTRACT: The objective of this work is to determine the effects of extension of a stream network through land drainage activities during the late 1800s on the hydrologic response of a watershed. The Mackinaw River Basin in Central Illinois was chosen as the focus and the pre‐land and post‐land drainage activity hydrologic responses were obtained through convolution of the hill slope and channel responses and compared. The hill slope response was computed using the kinematic wave model and the channel response was determined using the geomorphologic instantaneous unit hydrograph method. Our hypothesis was that the hydrologic response of the basin would exhibit the characteristic effects of settlement (i.e., increases in peak discharges and decreases in times to peak). This, indeed, is what occurred; however, the increase in peak discharges diminishes as scale increases, leaving only the decrease in times to peak. At larger scales, the dispersive effects of the longer hill slope lengths in the pre‐settlement scenario seem to balance the depressive effects of the longer path lengths in the post‐settlement scenario, thus the pre‐settlement and post‐settlement peak discharges are approximately equivalent. At small scales, the dispersion caused by the hill slope is larger in the pre‐settlement case; thus, the post‐settlement peak discharges are greater than the pre‐settlement.     

Distribution of Selected Soil and Water Conservation Practices in the U.S. as Identified with Google Earth

The proper representation of conservation practices on agricultural lands is an important factor in large‐scale assessments of water quality in the United States. Unfortunately, there are few publicly available data sources at the local level and even fewer at the national scale. In this research, randomly selected points within agricultural lands were examined for selected conservation practices using Google Earth aerial imagery by a team of interpreters. In total, 13,530 points had field boundaries digitized, and were subsequently examined and classified. The presence of terraces, grassed waterways, contour farming, center pivot irrigation, strip cropping, ponds, riparian vegetation, filter strips, and land cover were noted. Subjectivity among interpreters was evaluated using duplicate samples and was found to be similar to image misclassification rates in other research. Conservation practice adoption rates for selected major river basins compared favorably with data collected by the Conservation Effects Assessment Project. The frequency of occurrence of each conservation practice was summarized and presented by ecoregion. To facilitate future research, point level data and software source code developed in this research are available via the web at http://nlet.brc.tamus.edu/Conservation . Aerial imagery was found to be a powerful, inexpensive, and easily accessible tool to assess large‐scale conservation practice implementation for certain conservation practices.     

Development of a Cropland Management Dataset to Support U.S. Swat Assessments

The Soil and Water Assessment Tool (SWAT) is widely used in the United States (U.S.) to simulate hydrology and water quality simulation. Process‐based models like SWAT require a great deal of data to accurately represent the natural world, including topography, land use, soils, weather, and management. With the exception of management, all these data are available nationally from multiple sources. To date, credible SWAT studies in the U.S. have assembled suitable management data (operation scheduling, fertilization application rates, and plant growth parameterization). In this research, we develop a national management database for SWAT using existing U.S. Department of Agriculture data sources. These data are compatible with existing SWAT interfaces and are relatively easy to use. Although management data from local sources is preferred, these data are not always available. This work is intended to fill this void with more reasonable management data than the existing defaults. This national database covers all major cultivated crops and should facilitate improved SWAT applications in the U.S. These data were tested in two case studies and found to produce satisfactory SWAT predictions. The database developed in this research is freely available on the web.     

‘Wannabe Toxic-Free?’ From precautionary consumption to corporeal citizenship

Ecological citizens are increasingly encouraged to adopt ‘precautionary consumption’ – a set of practices aimed at shielding them from the potential health harms of exposures to everyday toxics. The utility and the effects of precautionary consumption in relation to common chemical exposures are investigated. Precautionary consumption is not only of questionable utility, but is fundamentally misguided as an approach for inspiring antitoxics organizing. The failure of this approach is in part due to its assumption of a naturally bounded, autonomous individual who is able to maintain an impermeable boundary between herself and the environment. Drawing on the work of material feminist theorists, it is argued that Gabrielson and Parady’s notion of corporeal citizenship, an approach that places bodies into a complex web of material, ecological relations entangled with the social, offers several strategic advantages for framing resistance strategies.     

Effect of octylphenol on physiologic features during growth in Arabidopsis thaliana

Alkylphenol ethoxylates are widely used as detergents, emulsifiers, solubilizers, wetting agents and dispersants. Octylphenol (OP) ethoxylates, one of alkylphenol ethoxylates, represent 15–20% of the market, and their metabolic residues may be discharged to surface waters, sediments and soils as a persistent and ubiquitous pollutant. We tested the response of Arabidopsis thaliana to different concentrations of OP. OP affected the germination percentage and mean germination period. 10 d treatment with OP, especially high concentration (10 and 50 mg L⁻¹), decreased shoot and root biomass and root length of 30 d-old A. thaliana. Content of chlorophyll was decreased but that of proline was increased in leaves with OP treatment. OP caused oxidative stress in leaves; malondialdehyde content was increased, and the activities of ascorbate peroxidase, catalase and superoxide dismutase were induced. OP affects the physiologic and morphologic features of A. thaliana during growth. Because plants might be exposed to OP for a long time in the surroundings, more attention needs to be paid to the effect of OP on plants.     

Characterization of eco-cement paste produced from waste sludges

In this study, marble sludge, sewage sludge, drinking water treatment plant sludge, and basic oxygen furnace sludge were used as replacements for limestone, sand, clay, and iron slag, respectively, as the raw materials for the production of cement in order to produce eco-cement. It was found that it is feasible to use marble sludge to replace up to 50% of the limestone and also that other materials can serve as total replacements for the raw materials typically used in the production of cement. The major components of Portland cement were all found in eco-cement clinkers. The eco-cement was confirmed to produce calcium hydroxide and calcium silicate hydrates during the hydration process, increasing densification with the curing age. The compressive strength (S_c) and microstructural evaluations conducted at 28 d revealed the usefulness of eco-cement. It was observed that the S_c data correlated linearly with the pore volume (P) data at 28 d. The proposed model equation could be represented as S_c = 178-461P (correlation coefficient, R² = 0.96). Two parameters, the large capillary pore volume and the medium capillary pore volume, were evaluated using multiple regression analysis.