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81.
Suzanne J.T. Hangx Christopher J. Spiers 《International Journal of Greenhouse Gas Control》2009,3(6):757-767
Qualitative proposals to control atmospheric CO2 concentrations by spreading crushed olivine rock along the Earth's coastlines, thereby accelerating weathering reactions, are presently attracting considerable attention. This paper provides a critical evaluation of the concept, demonstrating quantitatively whether or not it can contribute significantly to CO2 sequestration. The feasibility of the concept depends on the rate of olivine dissolution, the sequestration capacity of the dominant reaction, and its CO2 footprint. Kinetics calculations show that offsetting 30% of worldwide 1990 CO2 emissions by beach weathering means distributing of 5.0 Gt of olivine per year. For mean seawater temperatures of 15–25 °C, olivine sand (300 μm grain size) takes 700–2100 years to reach the necessary steady state sequestration rate and is therefore of little practical value. To obtain useful, steady state CO2 uptake rates within 15–20 years requires grain sizes <10 μm. However, the preparation and movement of the required material poses major economic, infrastructural and public health questions. We conclude that coastal spreading of olivine is not a viable method of CO2 sequestration on the scale needed. The method certainly cannot replace CCS technologies as a means of controlling atmospheric CO2 concentrations. 相似文献
82.
Businesses offering to make you or your company carbon neutral are proliferating on the Internet. The term carbon neutral is being defined by common usage. There are no standard ways of measuring your carbon emissions and so no standards for becoming carbon neutral. This paper examines eleven websites offering carbon neutrality. It compares online calculators, their results and the costs of offsetting calculated on the strength of those results. It traces two offset projects: one in Kenya, offering voluntary offsets and run by a not-for-profit organisation; one in India striving for UN Clean Development Mechanism status. The projects are traced from the online carbon offset retailer to the actual project on the ground in order to compare the online rhetoric with the time consuming and difficult work of developing community based projects in Third World countries. The paper offers a definition of carbon neutral based on the ways in which the term is being used. It also uncovers a range of issues for further discussion. 相似文献
83.
Turnover potentially leads to a new individual being selected into a work team. This study investigated the safety-specific trust which team members place in their organisation’s selection and induction processes, and related this to the perceived risk from new employees. The research was conducted with teams working in forest harvesting, an occupation which has high-turnover, high risk and a high accident rate. Results indicate that trust in induction processes was negatively correlated with perceived risk from a new employee. Team members also engaged in a number of safety ensuring behaviours when a new individual joined the team, and these were related to the level of perceived risk, and how much they cared about their team members’ safety. It is argued that trust in the safety-specific characteristics of an organisation’s selection and induction process may have negative consequences for safety. 相似文献
84.
de Grenade Rafael Rudow Joshua Taboada Hermoza Rossi Adauto Aguirre Maria Elena Scott Christopher A. Willems Bram Schultz Jennifer L. Varady Robert G. 《Regional Environmental Change》2017,17(3):789-802
Regional Environmental Change - Mountainous areas with extreme elevation gradients and corresponding ranges of biophysical and socioeconomic conditions are highly vulnerable to global change. We... 相似文献
85.
Maurer Edwin P. Roby Nicholas Stewart-Frey Iris T. Bacon Christopher M. 《Regional Environmental Change》2017,17(8):2421-2432
Regional Environmental Change - In addition to periodic long-term drought, much of Central America experiences a rainy season with two peaks separated by a dry period of weeks to over a month in... 相似文献
86.
Christopher K. Sass Tim D. Keane 《Journal of the American Water Resources Association》2012,48(4):774-787
Sass, Christopher K. and Tim D. Keane, 2012. Application of Rosgen’s BANCS Model for NE Kansas and the Development of Predictive Streambank Erosion Curves. Journal of the American Water Resources Association (JAWRA) 48(4): 774‐787. DOI: 10.1111/j.1752‐1688.2012.00644.x Abstract: Sedimentation of waterways and reservoirs directly related to streambank erosion threatens freshwater supply. This study sought to provide a tool that accurately predicts annual streambank erosion rates in NE Kansas. Rosgen (2001, 2006) methods were employed and 18 study banks were measured and monitored from 2007 through 2010 (May‐June). Bank profiles were overlaid to calculate toe pin area change due to erosional processes. Streambanks experienced varied erosion rates from similar Bank Erosion Hazard Index (BEHI)‐Near Bank Stress (NBS) combinations producing R2 values of 0.77 High‐Very High BEHI rating and 0.75 Moderate BEHI rating regarding predictive erosion curves for NE Kansas. Moderate ratings demonstrated higher erosion rates than High‐Very High ratings and BEHI trend lines intersected at lower NBS ratings, suggesting a discrepancy in the fit of the model to conditions in the NE Kansas region. BEHI model factors were evaluated and assessed for additional influences exerted in the region. Woody vegetation adjacent to the stream seemed to provide the most variation in erosion rates. This study’s findings allowed us to calibrate and modify the existing BEHI model according to woody vegetation occurrence levels along streambanks with high clay content. Modifications regarding vegetation occurrence of the BEHI model was completed and the results of these modifications generated new curves resulting in R2 values of 0.84 High‐Very High BEHI and 0.88 Moderate BEHI ratings. 相似文献
87.
Removal of tetrabromobisphenol A by conventional activated sludge, submerged membrane and membrane aerated biofilm reactors 总被引:1,自引:0,他引:1
The goal of this study was to compare removal efficiencies of tetrabromobisphenol A (TBBPA) using typical wastewater treatment technologies, and to identify the most significant mechanisms of removal. Two types of municipal wastewater reactors were studied: a full-scale conventional activated sludge (CAS) reactor with tertiary treatment; and three pilot-scale membrane bioreactors (MBRs) having different sludge retention times (SRTs). All four reactors were fed the same influent. A third reactor type, a membrane aerated biofilm reactor (MABR) was fed tap water, ammonia, and TBBPA. TBBPA in municipal influent ranged from 1 to 41 ng L−1 (n = 10). The CAS effluent had an average TBBPA concentration of 0.7 ± 1.3 ng L−1 (n = 3). Effluent concentrations from the MBRs were an average of 6 ± 6 ng L−1 TBBPA (n = 26). Significant TBBPA removal was observed in the MABR throughout the 5 week of study (p ? 0.05). Removal of TBBPA from wastewater treatment was found to be due to a combination of adsorption and biological degradation. Based on experimental results, nitrification is likely a key process therein. No significant relationship between removal of TBBPA and SRT was identified (p ? 0.05). 相似文献
88.
Agouridis CT Angel PN Taylor TJ Barton CD Warner RC Yu X Wood C 《Journal of environmental quality》2012,41(2):454-468
Surface mining is a common method for extracting coal in the coal fields of eastern Kentucky. Using the Forestry Reclamation Approach (FRA), which emphasizes the use of minimally compacted or loose-dumped spoil as a growth medium for trees, reclamation practitioners are successfully reestablishing forests. Yet, questions remain regarding the effects FRA has on the quality of waters discharged to receiving streams. To examine the effect of FRA on water quality, this study compared waters that were discharged from three types of spoils: predominantly brown, weathered sandstone (BROWN); predominantly gray, unweathered sandstone (GRAY); and an equal mixture of both aforementioned sandstones and shale (MIXED). The water quality parameters pH, EC, Ca, K, Mg, Na, NO-N, NH-N, SO, Cl, TC, suspended sediment concentration (SSC), settleable solids (SS), and turbidity were monitored over a 2-yr period on six 0.4-ha plots (two replications per spoil type). Generally, levels of Cl, SO, Ca, NO-N, NH-N, SS, SSC, and turbidity decreased over time. The pH for all spoils increased from about 7.5 to 8.5. The EC remained relatively level in the BROWN spoil, whereas the GRAY and MIXED spoils had downward trajectories that were approaching 500 μS cm. The value of 500 μS cm has been reported as the apparent threshold at which certain taxa such as Ephemeroptera (e.g., Mayfly) recolonize disturbed headwater streams of eastern Kentucky and adjacent coal-producing Appalachian states. 相似文献
89.
Estimating the Cumulative Ecological Effect of Local Scale Landscape Changes in South Florida 总被引:1,自引:0,他引:1
Hogan DM Labiosa W Pearlstine L Hallac D Strong D Hearn P Bernknopf R 《Environmental management》2012,49(2):502-515
Ecosystem restoration in south Florida is a state and national priority centered on the Everglades wetlands. However, urban
development pressures affect the restoration potential and remaining habitat functions of the natural undeveloped areas. Land
use (LU) planning often focuses at the local level, but a better understanding of the cumulative effects of small projects
at the landscape level is needed to support ecosystem restoration and preservation. The South Florida Ecosystem Portfolio
Model (SFL EPM) is a regional LU planning tool developed to help stakeholders visualize LU scenario evaluation and improve
communication about regional effects of LU decisions. One component of the SFL EPM is ecological value (EV), which is evaluated
through modeled ecological criteria related to ecosystem services using metrics for (1) biodiversity potential, (2) threatened
and endangered species, (3) rare and unique habitats, (4) landscape pattern and fragmentation, (5) water quality buffer potential,
and (6) ecological restoration potential. In this article, we demonstrate the calculation of EV using two case studies: (1)
assessing altered EV in the Biscayne Gateway area by comparing 2004 LU to potential LU in 2025 and 2050, and (2) the cumulative
impact of adding limestone mines south of Miami. Our analyses spatially convey changing regional EV resulting from conversion
of local natural and agricultural areas to urban, industrial, or extractive use. Different simulated local LU scenarios may
result in different alterations in calculated regional EV. These case studies demonstrate methods that may facilitate evaluation
of potential future LU patterns and incorporate EV into decision making. 相似文献
90.
Ground granulated blast furnace slag (ggbs) has been used to solidify air pollution control (APC) residues obtained from a major UK energy-from-waste plant. Samples were prepared with ggbs additions between 10 and 50 wt% of total dry mass and water/solids ratios between 0.35 and 0.80. Consistence, setting time, compressive strength and leaching characteristics have been investigated. Results indicated that the highly alkaline nature of APC residues due to the presence of free lime can be used to activate ggbs hydration reactions. Increasing ggbs additions and reducing the water content resulted in increased compressive strengths, with 50 wt% ggbs samples having average 28 d strengths of 20.6 MPa. Leaching tests indicate low physical encapsulation and minimal chemical fixation of chloride in ggbs solidified APC residues. The results suggest that more than 50 wt% ggbs additions would be required to treat APC residues to meet the current waste acceptance criteria limits for chloride. 相似文献