Improving ozone modeling in complex terrain at a fine grid resolution – Part II: Influence of schemes in MM5 on daily maximum 8-h ozone concentrations and RRFs (Relative Reduction Factors) for SIPs in the non-attainment areas

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.     

Mixing and transformation of Asian dust with pollution in the two dust storms over the northern China in 2006

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 PM_2.5 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.     

Governing green stormwater infrastructure: the Philadelphia experience

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.     

Phosphorus removal with by-products in a flow-through setting

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.     

Using Topography to Meet Wildlife and Fuels Treatment Objectives in Fire-Suppressed Landscapes

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.     

Climate Change Adaptation for the US National Wildlife Refuge System

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.     

U.S. Natural Resources and Climate Change: Concepts and Approaches for Management Adaptation

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.”     

北京市西北城区取暖期环境大气中PM10的物理化学特征

根据监测资料探讨了北京市西北城区取暖期PM₁₀的逐日变化规律和日变化规律.分别使用X射线衍射仪(XRD)和扫描电镜(SEM)研究PM₁₀中的矿物成分及其微观形貌特征.结果表明夜间PM₁₀浓度普遍高于白天.XRD分析显示颗粒物粒度越细,其中所含的矿物种类越少.SEM研究得出,单个PM₁₀颗粒类型可初步分为有链状集合体、簇状集合体、圆球状、片状和不规则形状等5类.从数量上看,PM₁₀主要来自燃煤和汽车尾气.     

夏季长三角地区臭氧非线性响应曲面模型的建立及应用

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.     

Organochlorine pesticide and heavy metal residues in some edible biota collected from Quanzhou Bay and Xinghua Bay, Southeast China

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...