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711.
Ryan J. K. Dunn Sasha Zigic Glenn R. Shiell 《Environmental monitoring and assessment》2014,186(10):6107-6125
Numerical models are useful for predicting the transport and fate of contaminants in dynamic marine environments, and are increasingly a practical solution to environmental impact assessments. In this study, a three-dimensional hydrodynamic model and field data were used to validate a far-field dispersion model that, in turn, was used to determine the fate of treated wastewater (TWW) discharged to the ocean via a submarine ocean outfall under hypothetical TWW flows. The models were validated with respect to bottom and surface water current speed and direction, and in situ measurements of total nitrogen and faecal coliforms. Variations in surface and bottom currents were accurately predicted by the model as were nutrient and coliform concentrations. Results indicated that the ocean circulation was predominately wind driven, evidenced by relatively small oscillations in the current speeds along the time-scale of the tide, and that dilution mixing zones were orientated in a predominantly north-eastern direction from the outfall and parallel to the coastline. Outputs of the model were used to determine the ‘footprint’ of the TWW plume under a differing discharge scenario and, particularly, whether the resultant changes in TWW contaminants, total nitrogen and faecal coliforms would meet local environmental quality objectives (EQO) for ecosystem integrity, shellfish harvesting and primary recreation. Modelling provided a practical solution for predicting the dilution of contaminants under a hypothetical discharge scenario and a means for determining the aerial extent of exclusion zones, where the EQOs for shellfish harvesting and primary recreation may not always be met. Results of this study add to the understanding of regional discharge conditions and provide a practical case study for managing impacts to marine environments under a differing TWW discharge scenario, in comparison to an existing scenario. 相似文献
712.
713.
Seymour Colleen L. Gillson Lindsey Child Matthew F. Tolley Krystal A. Curie Jock C. da Silva Jessica M. Alexander Graham J. Anderson Pippin Downs Colleen T. Egoh Benis N. Ehlers Smith David A. Ehlers Smith Yvette C. Esler Karen J. O’Farrell Patrick J. Skowno Andrew L. Suleman Essa Veldtman Ruan 《Ambio》2020,49(6):1211-1221
Ambio - A horizon scan was conducted to identify emerging and intensifying issues for biodiversity conservation in South Africa over the next 5–10 years. South African biodiversity... 相似文献
714.
Franke Alastair Falk Knud Hawkshaw Kevin Ambrose Skip Anderson David L. Bente Peter J. Booms Travis Burnham Kurt K. Ekenstedt Johan Fufachev Ivan Ganusevich Sergey Johansen Kenneth Johnson Jeff A. Kharitonov Sergey Koskimies Pertti Kulikova Olga Lindberg Peter Lindström Berth-Ove Mattox William G. McIntyre Carol L. Mechnikova Svetlana Mossop Dave Møller Søren Nielsen Ólafur K. Ollila Tuomo Østlyngen Arve Pokrovsky Ivan Poole Kim Restani Marco Robinson Bryce W. Rosenfield Robert Sokolov Aleksandr Sokolov Vasiliy Swem Ted Vorkamp Katrin 《Ambio》2020,49(3):762-783
Ambio - The peregrine falcon (Falco peregrinus) and the gyrfalcon (Falco rusticolus) are top avian predators of Arctic ecosystems. Although existing monitoring efforts are well established for both... 相似文献
715.
Determining sources of dissolved organic carbon and disinfection byproduct precursors to the McKenzie River, Oregon 总被引:2,自引:0,他引:2
Kraus TE Anderson CA Morgenstern K Downing BD Pellerin BA Bergamaschi BA 《Journal of environmental quality》2010,39(6):2100-2112
This study was conducted to determine the main sources of dissolved organic carbon (DOC) and disinfection byproduct (DBP) precursors to the McKenzie River, Oregon (USA). Water samples collected from the mainstem, tributaries, and reservoir outflows were analyzed for DOC concentration and DBP formation potentials (trihalomethanes [THMFPs] and haloacetic acids [HAAFPs]). In addition, optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) were measured to provide insight into DOM composition and assess whether optical properties are useful proxies for DOC and DBP precursor concentrations. Optical properties indicative of composition suggest that DOM in the McKenzie River mainstem was primarily allochthonous--derived from soils and plant material in the upstream watershed. Downstream tributaries had higher DOC concentrations than mainstem sites (1.6 +/- 0.4 vs. 0.7 +/- 0.3 mg L(-1)) but comprised < 5% ofmainstem flows and had minimal effect on overall DBP precursor loads. Water exiting two large upstream reservoirs also had higher DOC concentrations than the mainstem site upstream of the reservoirs, but optical data did not support in situ algal production as a source of the added DOC during the study. Results suggest that the first major rain event in the fall contributes DOM with high DBP precursor content. Although there was interference in the absorbance spectra in downstream tributary samples, fluorescence data were strongly correlated to DOC concentration (R2 = 0.98), THMFP (R2 = 0.98), and HAAFP (R2 = 0.96). These results highlight the value of using optical measurements for identifying the concentration and sources of DBP precursors in watersheds, which will help drinking water utilities improve source water monitoring and management programs. 相似文献
716.
David M. Falatko Sami A. Fam Jason Blackburn Glenn McGillicuddy George Pon Michael Gaudette 《补救:环境净化治理成本、技术与工艺杂志》2011,22(1):71-86
Enhanced anaerobic dechlorination is being conducted to remediate a 50‐acre groundwater area impacted with chlorinated volatile organic compounds (CVOCs). The plume, which is over 3,000 feet (ft) long, initially contained tetrachloroethene and breakdown products at concentrations of 2 to 3 milligrams per liter. The site's high groundwater flow velocity (greater than 1,000 ft per year) was incorporated into the design to help with amendment distribution. Bioaugmentation was conducted using a mixed culture containing Dehalococcoides ethenogenes. There is evidence that it has migrated to distances exceeding 600 ft. The major benefit of the high groundwater flow velocity is greater areal coverage by the remediation system, but the downside is the difficulty in delivering sufficient donor to create the required anaerobic conditions. Overall performance has been excellent with total CVOC reductions and conversion to ethene of 98 percent within a 25‐acre area downgradient of the treatment transect that has operated the longest. © 2011 Wiley Periodicals, Inc. 相似文献
717.
Winston T. Luke Paul Kelley Barry L. Lefer James Flynn Bernhard Rappenglück Michael Leuchner Jack E. Dibb Luke D. Ziemba Casey H. Anderson Martin Buhr 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4068-4080
Concentrations of CO, SO2, NO, NO2, and NOY were measured atop the University of Houston's Moody Tower supersite during the 2006 TexAQS-II Radical and Aerosol Measurement Project (TRAMP). The lowest concentrations of all primary and secondary species were observed in clean marine air in southerly flow. SO2 concentrations were usually low, but increased dramatically in sporadic midday plumes advected from sources in the Houston Ship Channel (HSC), located NE of the site. Concentrations of CO and NOx displayed large diurnal variations in keeping with their co-emission by mobile sources in the Houston Metropolitan Area (HMA). CO/NOx emission ratios of 5.81 ± 0.94 were observed in the morning rush hour. Nighttime concentrations of NOx (NOx = NO + NO2) and NOY (NOY = NO + NO2 + NO3 + HNO3 + HONO + 21N2O5 + HO2NO2 + PANs + RONO2 + p-NO3? + …) were highest in winds from the NNW-NE due to emission from mobile sources. Median ratios of NOx/NOY were approximately 0.9 overnight, reflecting the persistence and/or generation of NOZ (NOZ = NOY ? NOx) species in the nighttime Houston boundary layer, and approached unity in the morning rush hour. Daytime concentrations of NOx and NOY were highest in winds from the HSC. NOx/NOY ratios reached their minimum values (median ca 0.63) from 1300 to 1500 CST, near local solar noon, and air masses often retained enough NOx to sustain additional O3 formation farther downwind. HNO3 and PANs comprised the dominant NOZ species in the HMA, and on a median basis represented 17–20% and 12–15% of NOY, respectively, at midday. Concentrations of HNO3, PANs, and NOZ, and fractional contributions of these species to NOY, were at a maximum in NE flow, reflecting the source strength and reactivity of precursor emissions in the HSC. As a result, daytime O3 concentrations were highest in air masses with HSC influence. Overall, our findings confirm the impact of the HSC as a dominant source region within the HMA. A comparison of total NOY measurements with the sum of measured NOY species (NOYi = NOx + HNO3 + PANs + HONO + p-NO3?) yielded excellent overall agreement during both day ([NOY](ppb) = ([NOYi](ppb)11.03 ± 0.16) ? 0.42; r2 = 0.9933) and night ([NOY](ppb) = ([NOYi](ppb)11.01 ± 0.16) + 0.18; r2 = 0.9975). A similar comparison between NOY–NOx concentrations and the sum of NOZi (NOZi = HNO3 + PANs + HONO + p-NO3?) yielded good overall agreement during the day ([NOZ](ppb) = ([NOZi](ppb)11.01 ± 0.30) + 0.044 ppb; r2 = 0.8527) and at night ([NOZ](ppb) = ([NOZi](ppb)11.12 ± 0.69) + 0.16 ppb; r2 = 0.6899). Median ratios of NOZ/NOZi were near unity during daylight hours but increased to approximately 1.2 overnight, a difference of 0.15–0.50 ppb. Differences between NOZ and NOZi rarely exceeded combined measurement uncertainties, and variations in NOZ/NOZi ratios may have resulted solely from errors in conversion efficiencies of NOY species and changes in NOY composition. However, nighttime NOZ/NOZi ratios and the magnitude of NOZ ? NOZi differences were generally consistent with recent observations of ClNO2 in the nocturnal Houston boundary layer. 相似文献
718.
Effectiveness of grass barriers and vegetative filter strips (FS) for reducing transport of sediment and nutrients in runoff may depend on runoff flow conditions. We assessed the performance of (1) switchgrass (Panicum virgatum L.) barriers (0.7 m) planted above fescue (Festuca arundinacea Schreb.) filter strips under interrill (B-FS) and concentrated flow (CF-B-FS), and (2) fescue alone under interrill (FS) and concentrated flow (CF-FS) for reducing runoff, sediment, nitrogen (N), and phosphorus (P) loss from fallow plots on a Mexico silt loam. We compared exclusively the performance of barriers and filter strips separately under interrill and concentrated flow. Runoff and sediment were sampled at 1 m above and at 0.7, 4, and 8 m below the downslope edge of the sediment source area. Filter strips under interrill flow reduced 80% and those under concentrated flow reduced 72% of sediment at 0.7 m (P < 0.01). With the addition of supplemental runoff simulating runoff from a larger sediment source area, FS reduced 80%, but CF-FS reduced only 60% of sediment. The FS reduced organic N and NO(3)-N by an additional 50% (P < 0.01) more than CF-FS at 0.7 m. Although the effectiveness of both treatments increased with increasing width, CF-FS removed less sediment than FS alone at 8 m (P < 0.04). In contrast, barriers above filter strips under interrill and concentrated flow were equally effective at 8 m; decreasing runoff by 34%, sediment by 99%, and nutrients by 70%. Thus, barriers combined with FS can be an effective alternative to FS alone for sites where concentrated flows may occur. 相似文献
719.
Elizabeth Ramlal Denys Yemshanov Glenn Fox Daniel McKenney 《Journal of environmental management》2009
This study explores the economic attractiveness of afforestation as a strategy for the joint production of fibre, carbon storage and biosolids (treated municipal sewage sludge) disposal for municipalities in Southern and Central Ontario, Canada. We use a spatial, stochastic model, the Canadian Forest Service Afforestation Feasibility Model (CFS-AFM), to simulate a range of spatial biosolids application scenarios in hybrid poplar afforestation projects. Results suggest that such joint afforestation strategies could be financially attractive. Significant cost savings can be expected through decreases in transportation distances and avoided waste disposal fees. Sensitivity analysis is used to examine the effects of variations in critical model parameters on net present values. Our findings indicate that waste disposal savings from application of biosolids on hybrid poplar plantations combined with incentives for landowners to sequester carbon can easily compete with agricultural land rental values in some regions of Ontario. Social acceptance of this kind of activity, however, may be an impediment to adoption. 相似文献
720.
Lessons for PPGIS from the application of a decision-support tool in the Nova Forest Alliance of Nova Scotia, Canada 总被引:1,自引:0,他引:1
The effectiveness of a decision-support tool created to identify protected-area potential within the Nova Forest Alliance (NFA) of Nova Scotia, Canada is assessed from the perspective of a public participatory geographic information system (PPGIS) approach. The application sought to create an integrated GIS-based decision-support tool for community-focused communication and conservation assessment among NFA partners (including private woodland owners, government agencies, forest companies, and non-government organizations) and potential application within other model forests in Canada. The application illustrated that the GIS-based tool, once set up and populated with the necessary data, was able to generate effective visual alternatives to support decision making within the NFA community and elsewhere. However, from a PPGIS perspective, the application faced challenges that influenced the efficacy of its implementation: (1) limitations arose around data quality, use and sharing policies; (2) although opportunities for participation by the NFA partnership were initiated, these proved insufficient to achieve adequate engagement, buy in and support for the process and outcomes; and (3) the expert-grounded GIS-based tool requires a greater degree of expertise than may currently be present in the community. These challenges limit its ongoing use in the NFA and its potential utility in other model forests. For PPGIS-decision-support applications to be effective in the NFA and elsewhere, it is suggested that the following conditions be met: (1) implementation of geographically based data policies to allow for greater data accessibility, specifically with fewer bureaucratic and private sector barriers; (2) engagement of community partners in the initial project design, goal-setting and subsequent stages, even if this requires extensions to anticipated timelines; and (3) development of effective participatory technical systems that meet the needs of participants without being so complex as to constitute a barrier to their use. 相似文献