MODELING URBAN NONPOINT SOURCE POLLUTION WITH A GEOGRAPHIC INFORMATION SYSTEM1

ABSTRACT: A geographic information system (GIS) was a useful aid in the assessment of urban nonpoint source pollution and the development of a pollution control strategy. The GIS was used for data integration and display, and to provide data for a nonpoint source model. An empirical nonpoint source loading model driven by land use was used to estimate pollutant loadings of priority pollutants. Pollutant loadings were estimated at fine spatial resolution and aggregated to storm sewer drainage basins (sewersheds). Eleven sewersheds were generated from digital versions of sewer maps. The pollutant loadings of individual land use polygons, derived as the units of analysis from street blocks, were aggregated to get total pollutant loadings within each sewershed. Based on the model output, a critical sewershed was located. Pollutant loadings at major sewer junctions within the critical sewershed were estimated to develop a mitigation strategy. Two approaches based on the installation of wet ponds were investigated - a regional approach using one large wet pond at the major sewer outfall and a multisite approach using a number of smaller sites for each major sewer junction. Cost analyses showed that the regional approach would be more cost effective, though it would provide less pollution control.     

Nitrate Concentrations in Springs Flowing into the Lower Flint River Basin,Georgia U.S.A.1

Allums, Stephanie E., Stephen P. Opsahl, Stephen W. Golladay, David W. Hicks, and L. Mike Conner, 2012. Nitrate Concentrations in Springs Flowing Into the Lower Flint River Basin, Georgia U.S.A. Journal of the American Water Resources Association (JAWRA) 48(3): 423-438. DOI: 10.1111/j.1752-1688.2011.00624.x Abstract: Analysis of long-term data from (2001-2009) in four springs that discharge from the Upper Floridan aquifer into the Flint River (southwestern Georgia, United States) indicate aquifer and surface-water susceptibility to nutrient loading. Nitrate-N concentrations ranged from 1.74 to 3.30 mg/l, and exceeded historical levels reported for the Upper Floridan aquifer (0.26-1.52 mg/l). Statistical analyses suggest increasing nitrate-N concentration in groundwater discharging at the springs (n = 146 over eight years) and that nitrate-N concentration is influenced by a dynamic interaction between depth to groundwater (an indicator of regional hydrologic conditions) and land use. A one-time synoptic survey of 10 springs (6 springs in addition to the 4 previously mentioned) using stable isotopes generated δ¹⁵N-NO₃⁻ values (4.8-8.4‰ for rural springs and 7.7-13.4‰ for developed/urban springs) suggesting mixed sources (i.e., fertilizer, animal waste, and soil organic nitrogen) of nitrate-N to rural springs and predominantly animal/human waste to urban springs. These analyses indicate a direct relation between nitrate-N loading since the 1940s and intensification of agricultural and urban land use. This study demonstrates the importance of evaluating long-term impacts of land use on water quality in groundwater springs and in determining how rapidly these changes occur.     

A transatlantic approach to sustainability? The perspective of sociology

Differing views of the state and varying ideological postures in the United States and Europe place ??invisible and clandestine?? obstacles against the smooth functioning of transatlantic treaties, agreements, and cooperation in general. These differing views and postures must be rendered visible and acknowledged if efforts to perpetuate a cross-Atlantic dialog are to be viable and stable. Neither the advantages of sharing technology nor common economic and political interests will alone adequately ground cooperation. Sociologists in particular are aware of the ways in which indigenous values and beliefs frequently endure, despite the homogenizing structural change that accompanies industrialization, urbanization, and globalization, and cause misperceptions and misunderstandings.     

Nitrogen source effects on nitrous oxide emissions from irrigated no-till corn

Nitrogen fertilization is essential for optimizing crop yields; however, it may potentially increase nitrous oxide (N2O) emissions. The study objective was to assess the ability of commercially available enhanced-efficiency N fertilizers to reduce N2O emissions following their application in comparison with conventional dry granular urea and liquid urea-ammonium nitrate (UAN) fertilizers in an irrigated no-till (NT) corn (Zea mays L.) production system. Four enhanced-efficiency fertilizers were evaluated: two polymer-coated urea products (ESN and Duration III) and two fertilizers containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus). Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Enhanced-efficiency fertilizers significantly reduced growing-season N2O-N emissions in comparison with urea, including UAN. SuperU and UAN+AgrotainPlus had significantly lower N2O-N emissions than UAN. Compared with urea, SuperU reduced N2O-N emissions 48%, ESN 34%, Duration III 31%, UAN 27%, and UAN+AgrotainPlus 53% averaged over 2 yr. Compared with UAN, UAN+AgrotainPlus reduced N2O emissions 35% and SuperU 29% averaged over 2 yr. The N2O-N loss as a percentage of N applied was 0.3% for urea, with all other N sources having significantly lower losses. Grain production was not reduced by the use of alternative N sources. This work shows that enhanced-efficiency N fertilizers can potentially reduce N2O-N emissions without affecting yields from irrigated NT corn systems in the semiarid central Great Plains.     

Modelling the photooxidation of ULP,E5 and E10 in the CSIRO smog chamber

The photooxidation of fuel vapour was investigated in a smog chamber and simulated using three chemical mechanisms, the Master Chemical Mechanism (MCMv3.1), SAPRC-99 and the Carbon Bond chemical mechanism (CB05). Three varieties of fuel were used, unleaded petrol (ULP) and two ULP-ethanol blends which contained 5% and 10% ethanol (E5, E10). The fuel vapours were introduced into the chamber using two methods, by injecting the vapours from wholly evaporated fuel directly, and by injecting the headspace vapour from fuel equilibrated at 38 °C. The chamber experiments were simulated using the selected mechanisms and comparisons made with collected experimental data.The SAPRC-99 mechanism reproduced Δ(O₃–NO) more accurately for almost all fuel types and injection modes, with negligible model error for both injection modes. The average model error for MCM simulations was ?16% and for CB05 the average model error was ?34%. The predictions for the CB05 mechanism varied depending on injection mode, the Δ(O₃–NO) model error for wholly evaporated experiments was ?44%, compared to ?24% for headspace vapour experiments. The difference in aromatic content between experiments of different injection modes was likely to be the cause of the difference in model error for CB05. The model error for all headspace experiments was dependent upon the initial carbon monoxide concentrations.The results for Δ(O₃–NO) were matched by the prediction of other key products, with formaldehyde predicted to within 20% by both SAPRC and the MCM. The addition of ethanol to the base SAPRC mechanism altered the predictions of Δ(O₃–NO) by less than 2%. Changes observed in the concentrations of formaldehyde and acetaldehyde were consistent with the expected yields from ethanol oxidation.     

Valuing Recreational Benefits of Coral Reefs: The Case of Mombasa Marine National Park and Reserve, Kenya

A contingent valuation study was conducted with adult Kenyan citizens and foreign tourists to estimate the value of recreational benefits arising from coral reefs at Mombasa Marine National Park and Reserve (MMNPR), and to assess the implications for local reef management. Citizen and foreign visitors to MMNPR were willing to pay an extra $2.2 (median = $2.2 (median = 1.6) and $8 (median = $8 (median = 6.7) per visit respectively, in addition to current park entrance fees, to support reef quality improvements. By aggregating visitors’ willingness to pay bids over the number of visitors to MMNPR in 2006–2007 the value of benefits was estimated at 346,733, which was more than twice the total annual operational expenditure of346,733, which was more than twice the total annual operational expenditure of 152,383 for MMNPR. The findings indicate that annual revenues from citizen and foreign visitors may be increased by 60% to 261,932 through the implementation of proposed higher park fees of261,932 through the implementation of proposed higher park fees of 3.10 for citizens and $15 for foreign visitors. However, any fee increase would serve to intensify concerns among citizens that only relatively affluent Kenyans can afford to visit MMNPR. Park managers need to demonstrate that the extra revenue would be used to fund the proposed conservation activities. This valuation study demonstrates that visitors are prepared to pay higher user fees for access to the marine protected area revealing considerable untapped resource to finance reef quality improvements.     

The Steubenville Comprehensive Air Monitoring Program (SCAMP): Concentrations and Solubilities of PM2.5 Trace Elements and Their Implications for Source Apportionment and Health Research

Abstract

The elemental compositions of the water-soluble and acid-digestible fractions of 24-hr integrated fine particulate matter (PM_2.5) samples collected in Steubenville, OH, from 2000 to 2002 were determined using dynamic reaction cell inductively coupled plasma-mass spectrometry. The water-soluble elemental compositions of PM_2.5 samples collected at four satellite monitoring sites in the surrounding region were also determined. Fe was the most abundant but least water soluble of the elements determined at the Steubenville site, having a mean ambient concentration of 272 µg/m³ and a median fractional solubility of 6%. Fe solubility and its correlations with SO₄ ^2? and temperature varied significantly by season, consistent with the hypothesis that secondary sulfates may help to mobilize soluble Fe under suitable summertime photochemical conditions. Significantly higher ambient concentrations were observed at Steubenville than at each of the four satellite sites for 10 of the 18 elements (Al, As, Ca, Cd, Fe, Mg, Mn, Na, Pb, and Zn) determined in the water-soluble PM_2.5 fraction. Concentrations of Fe, Mn, and Zn at Steubenville were substantially higher than concentrations reported recently for larger U.S. cities. Receptor modeling identified seven sources affecting the Steubenville site. An (NH₄)₂SO₄-dominated source, likely representing secondary PM_2.5 from coal-fired plants to the west and southwest of Steubenville, accounted for 42% of the PM_2.5 mass, and two sources likely dominated by emissions from motor vehicles and from iron and steel facilities in the immediate Steubenville vicinity accounted for 20% and 10%, respectively. Other sources included an NH₄NO₃ source (15%), a crustal source (6%), a mixed nonferrous metals and industrial source (3%), and a primary coal combustion source (3%). Results suggest the importance of very different regional and local source mechanisms in contributing to PM_2.5 mass at Steubenville and reinforce the need for further research to elucidate whether metals such as Fe, Mn, and Zn play a role in the PM_2.5 health effects observed previously there.     

Oxygen depletion in relation to water residence times

The relationship between residence time and oxygen saturation was investigated in a mesotidal lagoon in southern Portugal. The system receives no significant freshwater input during the summer months and has a high evaporation rate. These features enable an estimate of residence time from the salinity differences between ocean water entering the system and lagoon water. More than 10,000 GPS referenced measurements of oxygen saturation, temperature and salinity were made during large spring tides in September, 2006. The lowest oxygen saturation ( approximately 44%) was measured in the waters with the highest calculated residence times (7 days). There was a significant linear decrease in the oxygen saturation with increasing residence time of approximately 16% per day. This was similar to the rate measured on a neap tide in August, 2005. The high salinity, low oxygen saturated water was spatially confined to one inner channel, except at high water when this water was pushed into other channels. Although the tides investigated were the largest for several years, the oxygen saturation did not exceed 70% in this inner region. It is proposed that the direct discharge of oxygen consuming effluent, including domestic sewage, into this inner channel is responsible for this persistent oxygen deficit.     

Influence of drought and municipal sewage effluents on the baseflow water chemistry of an upper piedmont river

The Reedy River in South Carolina is affected by the urban area of Greenville, the third most populous city in the state, and by the effluents from two large-scale municipal wastewater treatment plants (WWTPs) located on the river. Riverine water chemistry was characterized using grab samples collected annually under spring season baseflow conditions. During the 4-year time period associated with this study, climatic variations included two severe drought spring seasons (2001 and 2002), one above-normal precipitation spring season (2003), and one below-normal precipitation spring season (2004). The influence of drought and human activities on the baseflow chemistry of the river was evaluated by comparing concentrations of dissolved anions, total metals, and other important water chemistry parameters for these different years. Concentrations of copper and zinc, common non-point source contaminants related to urban activities, were not substantially elevated in the river within the urban area under baseflow conditions when compared with headwater and tributary samples. In contrast, nitrate concentrations increased from 1.2–1.6 mg/l up to 2.6–2.9 mg/l through the urban stream reach. Concentrations of other major anions (e.g., sulfate, nitrate) also increased along the reach, suggesting that the river receives continuous inputs of these species from within the urban area. The highest concentrations of major cations and anions typically were observed immediately downstream from the two WWTP effluent discharge locations. Attenuation of nitrate downstream from the WWTPs did not always track chloride changes, suggesting that nitrate concentrations were being controlled by biochemical processes in addition to physical processes. The relative trends in decreasing nitrate concentrations with downstream distance appeared to depend on drought versus non-drought conditions, with biological processes presumably serving as a more important control during non-drought spring seasons.