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171.
Yunhee Kim Joshua S. Fu Terry L. Miller 《Atmospheric environment (Oxford, England : 1994)》2010,44(17):2116-2124
Part II presents a comprehensive evaluation of CMAQ for August of 2002 on twenty-one sensitivity simulations (detailed in Part I) in MM5 to investigate the model performance for O3 SIPs (State Implementation Plans) in the complex terrain. CMAQ performance was quite consistent with the results of MM5, meaning that accurate meteorological fields predicted in MM5 as an input resulted in good model performance of CMAQ. In this study, PBL scheme plays a more important role than its land surface models (LSMs) for the model performance of CMAQ. Our results have shown that the outputs of CMAQ on eighteen sensitivity simulations using two different nudging coefficients for winds (2.5 and 4.5 × 10?4 s?1, respectively) tend to under predict daily maximum 8-h ozone concentrations at valley areas except the TKE PBL sensitivity simulations (ETA M-Y PBL scheme with Noah LSMs and 5-layer soil model and Gayno-Seaman PBL) using 6.0 × 10?4 s?1 with positive MB (Mean Bias). At mountain areas, none of the sensitivity simulations has presented over predictions for 8-h O3, due to relatively poor meteorological model performance. When comparing 12-km and 4-km grid resolutions for the PX simulation in CMAQ statistics analysis, the CMAQ results at 12-km grid resolution consistently show under predictions of 8-h O3 at both of valley and mountain areas and particularly, it shows relatively poor model performance with a 15.1% of NMB (Normalized Mean Bias). Based on our sensitivity simulations, the TKE PBL sensitivity simulations using a maximum value (6 × 10?4) among other sensitivity simulations yielded better model performance of CMAQ at all areas in the complex terrain. As a result, the sensitivity of RRFs to the PBL scheme may be considerably significant with about 1–3 ppb in difference in determining whether the attainment test is passed or failed. Furthermore, we found that the result of CMAQ model performance depending on meteorological variations is affected on estimating RRFs for attainment demonstration, indicating that it is necessary to improve model performance. Overall, G_c (Gayo-Seaman PBL scheme) using the coefficient for winds, 6 × 10?4 s?1, sensitivity simulation predicts daily maximum 8-h ozone concentration closer to observations during a typical summer period from May to September and provides generally low future design values (DVFs) at valley and mountain areas compared to other simulations. 相似文献
172.
Wenjie Zhang Guoshun Zhuang Kan Huang Juan Li Rong Zhang Qiongzhen Wang Yele Sun Joshua S. Fu Ying Chen Dongqun Xu Wei Wang 《Atmospheric environment (Oxford, England : 1994)》2010,44(28):3394-3403
To study the mixing and transformation of Asian dust with pollution in the two dust storms over the northern China in 2006, both TSP and PM2.5 samples were collected at three sites of northern China in addition to the dry deposition samples collected in an episode in Beijing. 23 elements, 15 ions, and 16 PAHs in each sample were analyzed. The two dust storms in northern China were observed in April 8–10 (DS1) and April 16–18 (DS2). Compared to DS2, DS1 was weaker and more polluted with stronger mixing between crustal and pollutant aerosols during their long-range transport. The concentrations of pollution species, e.g. pollution elements, ions, and PAHs were higher in DS1 than that in DS2, while the crustal species showed adverse variation. The correlation between chemical species and Al and between PAH(4) and PAH(5,6) further confirmed the stronger chemical transformation and aerosol mixing in DS1 than that in DS2. Back trajectory and chemical analysis revealed that in DS1 the air masses at Beijing were mostly from southern or southwestern direction at lower altitude with much more pollution, while in DS2 the air masses were mostly from the northwestern and northern direction with dust mainly, which explained why there was a stronger mixing of dust with pollution aerosol in DS1 than that in DS2 over Beijing. 相似文献
173.
Many cities throughout the world are adopting green infrastructure techniques to reduce stormwater and sewer overflows into waterways, which is particularly problematic for places experiencing more frequent and severe rain events. Governance of green stormwater implementation is proving to be as important as the techniques themselves. Building on the climate and sustainability governance literature, we argue that effective governance requires planning across city departments, experimentation and a strategy for organisational learning. We employ a case study of Philadelphia, the first city in the United States to attempt an entirely green approach to meeting federal regulations to examine issues of governance that emerged and how they were addressed. The case study draws on interviews with fourteen public and private sector actors involved in implementation, a site visit to observe the installations and to discuss the approach with a key planner, and grey literature. We find that silos can be broken down and that if open communications and a willingness to change practices are present, obstacles cited in the literature can be overcome. The key implication is that the three elements of governance need to be built into the green infrastructure planning process. While the analysis focuses on a US city, the departments involved and the governance needs of green stormwater infrastructure are similar in cities in much of the world. 相似文献
174.
Phosphorus (P) losses to surface waters can result in eutrophication. Some industrial by-products have a strong affinity for dissolved P and may be useful in reducing nonpoint P pollution with landscape-scale runoff filters. Although appreciable research has been conducted on characterizing P sorption by industrial by-products via batch isotherms, less data are available on P sorption by these materials in a flow-through context integral to a landscape P filter. The objectives of this study were to evaluate several industrial by-products for P sorption in a flow-through setting, to determine material chemical properties that have the greatest impact on P sorption in a flow-through setting, and to explore how retention time (RT) and P concentration affect P removal. Twelve materials were characterized for chemical properties that typically influence P removal and subjected to flow-through P sorption experiments in which five different RTs and P concentrations were tested. The impact of RT and P concentrations on P removal varied based on material chemical properties, mainly as a function of oxalate-extractable aluminum (Al), iron (Fe), and water-soluble (WS) calcium (Ca). Statistical analysis showed that materials elevated in oxalate-extractable Al and Fe and WS Ca and that were highly buffered above pH 6 were able to remove the most P under flow-through conditions. Langmuir sorption maximum values from batch isotherms were poorly correlated with and overestimated P removal found under flow-through conditions. Within the conditions tested in this study, increases in RT and inflow P concentrations increased P removal among materials most likely to remove P via precipitation, whereas RT had little effect on materials likely to remove P via ligand exchange. 相似文献
175.
Emma C. Underwood Joshua H. Viers James F. Quinn Malcolm North 《Environmental management》2010,46(5):809-819
Past forest management practices, fire suppression, and climate change are increasing the need to actively manage California
Sierra Nevada forests for multiple environmental amenities. Here we present a relatively low-cost, repeatable method for spatially
parsing the landscape to help the U.S. Forest Service manage for different forest and fuel conditions to meet multiple goals
relating to sensitive species, fuels reduction, forest products, water, carbon storage, and ecosystem restoration. Using the
Kings River area of the Sierra Nevada as a case study, we create areas of topographically-based units, Landscape Management
Units (LMUs) using a three by three matrix (canyon, mid-slope, ridge-top and northerly, southerly, and neutral aspects). We
describe their size, elevation, slope, aspect, and their difference in inherent wetness and solar radiation. We assess the
predictive value and field applicability of LMUs by using existing data on stand conditions and two sensitive wildlife species.
Stand conditions varied significantly between LMUs, with canyons consistently having the greatest stem and snag densities.
Pacific fisher (Martes pennanti) activity points (from radio telemetry) and California spotted owl (Strix occidentalis occidentalis) nests, roosts, and sightings were both significantly different from uniform, with a disproportionate number of observations
in canyons, and fewer than expected on ridge-tops. Given the distinct characteristics of the LMUs, these units provide a relatively
simple but ecologically meaningful template for managers to spatially allocate forest treatments, thereby meeting multiple
National Forest objectives. These LMUs provide a framework that can potentially be applied to other fire-dependent western
forests with steep topographic relief. 相似文献
176.
Brad Griffith J. Michael Scott Robert Adamcik Daniel Ashe Brian Czech Robert Fischman Patrick Gonzalez Joshua Lawler A. David McGuire Anna Pidgorna 《Environmental management》2009,44(6):1043-1052
Since its establishment in 1903, the National Wildlife Refuge System (NWRS) has grown to 635 units and 37 Wetland Management
Districts in the United States and its territories. These units provide the seasonal habitats necessary for migratory waterfowl
and other species to complete their annual life cycles. Habitat conversion and fragmentation, invasive species, pollution,
and competition for water have stressed refuges for decades, but the interaction of climate change with these stressors presents
the most recent, pervasive, and complex conservation challenge to the NWRS. Geographic isolation and small unit size compound
the challenges of climate change, but a combined emphasis on species that refuges were established to conserve and on maintaining
biological integrity, diversity, and environmental health provides the NWRS with substantial latitude to respond. Individual
symptoms of climate change can be addressed at the refuge level, but the strategic response requires system-wide planning.
A dynamic vision of the NWRS in a changing climate, an explicit national strategic plan to implement that vision, and an assessment
of representation, redundancy, size, and total number of units in relation to conservation targets are the first steps toward
adaptation. This adaptation must begin immediately and be built on more closely integrated research and management. Rigorous
projections of possible futures are required to facilitate adaptation to change. Furthermore, the effective conservation footprint
of the NWRS must be increased through land acquisition, creative partnerships, and educational programs in order for the NWRS
to meet its legal mandate to maintain the biological integrity, diversity, and environmental health of the system and the
species and ecosystems that it supports. 相似文献
177.
Jordan M. West Susan H. Julius Peter Kareiva Carolyn Enquist Joshua J. Lawler Brian Petersen Ayana E. Johnson M. Rebecca Shaw 《Environmental management》2009,44(6):1001-1021
Public lands and waters in the United States traditionally have been managed using frameworks and objectives that were established
under an implicit assumption of stable climatic conditions. However, projected climatic changes render this assumption invalid.
Here, we summarize general principles for management adaptations that have emerged from a major literature review. These general
principles cover many topics including: (1) how to assess climate impacts to ecosystem processes that are key to management
goals; (2) using management practices to support ecosystem resilience; (3) converting barriers that may inhibit management
responses into opportunities for successful implementation; and (4) promoting flexible decision making that takes into account
challenges of scale and thresholds. To date, the literature on management adaptations to climate change has mostly focused
on strategies for bolstering the resilience of ecosystems to persist in their current states. Yet in the longer term, it is
anticipated that climate change will push certain ecosystems and species beyond their capacity to recover. When managing to
support resilience becomes infeasible, adaptation may require more than simply changing management practices—it may require
changing management goals and managing transitions to new ecosystem states. After transitions have occurred, management will
again support resilience—this time for a new ecosystem state. Thus, successful management of natural resources in the context
of climate change will require recognition on the part of managers and decisions makers of the need to cycle between “managing
for resilience” and “managing for change.” 相似文献
178.
夏季长三角地区臭氧非线性响应曲面模型的建立及应用 总被引:2,自引:0,他引:2
2013年8月上旬,长三角地区发生了一次大范围高浓度臭氧污染事件.本研究基于WRF-CMAQ空气质量模型系统,结合长三角地区大气污染物排放清单,构建了臭氧与其前体物之间的非线性响应曲面模型(Response surface modeling,RSM).基于RSM探讨了长三角地区O_3化学的敏感性特征,分析了上海市O_3的来源并预测不同情景下O_3的变化,提出O_3污染的最优控制方案.研究结果表明,长三角地区夏季O3主控因素区域差别较大,上海环科院、杭州卧龙桥、南京玄武湖等城区点位属于VOC控制型;徐州铜山、合肥肥西、丽水青田等郊区属于NOx控制型.O_3的敏感性特征在不同浓度水平下也呈现较大差异,随着O_3浓度水平的升高,各地区NOx敏感性均有所增加.从区域来源来看,远距离传输对平日上海O_3贡献较大,占50%以上;而在O_3污染日,本地及区域贡献为72.1%,而远距离传输贡献下降至27.9%.快速预测了110组减排情景,表明在本地及区域前体物均减排70%的情况下,2013年8月上海O_3浓度能完全达标. 相似文献
179.
Mangala Yatawar Shihua Qi Odhiambo Joshua Owago Yuan Zhang Dan Yang Junpeng Zhang Julia E Burnet 《环境科学学报(英文版)》2010,22(2):314-320
In order to assess the contamination of edible marine organisms in Quanzhou and Xinghua Bays,Fujian Province,China,concentrations of organochlorine pesticides(hexachlorocyclohexane isomers or HCHs and dichlorodiphenyltrichloroethane isomers/derivatives or DDTs) and heavy metals(Cu,Pb,Zn,As,Cr,Cd,Ni and Hg) in 13 species collected from different sites in the bays were analyzed by GC-ECD and ICP-MS.The concentration of the sum of DDTs exceeded that the sum of HCHs in the samples.Most of the organisms showed h... 相似文献
180.
Peter A. Valberg Barbara D. Beck Pamela D. Boardman Joshua T. Cohen 《Environmental geochemistry and health》1998,20(2):61-66
Several published studies have examined skin-cancer prevalence in regions of the USA that have concentrations of arsenic above the USA drinking-water standard. Those studies with adequate exposure and health outcome data did not report any skin cancer cases. Because the USA's arsenic concentrations are relatively low compared to some other countries and the study populations are small, the absence of reported skin-cancer cases could be due to an absence of risk in USA populations or random variability from a predicted risk. We used the current EPA arsenic cancer slope factor (CSF) model, which is derived from Taiwanese populations exposed to high levels of arsenic, to predict the expected number of skin cancers. We then conducted a likelihood ratio analysis, which showed that a null hypothesis (no additional skin cancer risk from arsenic) was approximately 2.2 times more likely than the hypothesis that ingested arsenic causes the predicted rate of skin cancers. Although based on small numbers, our analysis of USA populations indicates that the CSF derived from arsenic exposure in Taiwanese populations may be an overestimate when applied to USA populations. 相似文献