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221.
把中尺度气象模式MM5的模拟数据输入到AERMOD中,以一次模拟为例表明:①MM5模拟的地面气象数据风向频率偏差较大,日平均温度和风速变化趋势与实测基本一致,模拟值偏大;②模拟探空数据和实测地面气象数据AERMOD预测结果与采用实测气象数据的相比有较好的一致性,模拟地面和气象数据的预测结果与实测气象数据的预测结果相比误差较大。 相似文献
222.
Numerical Investigation of Boundary-Layer Evolution and Nocturnal Low-Level Jets: Local versus Non-Local PBL Schemes 总被引:3,自引:0,他引:3
Kesu Zhang Huiting Mao Kevin Civerolo Stephen Berman Jia-Yeong Ku S. Trivikrama Rao Bruce Doddridge C. Russell Philbrick Richard Clark 《Environmental Fluid Mechanics》2001,1(2):171-208
Numerical simulations of the evolution of the planetary boundary layer (PBL) and nocturnal low-level jets (LLJ) have been carried out using MM5 (version 3.3) with four-dimensional data assimilation (FDDA) for a high pollution episode in the northeastern United States during July 15–20, 1999. In this paper, we assess the impact of different parameterizations on the PBL evolution with two schemes: the Blackadar PBL, a hybrid local (stable regime) and non-local (convective regime) mixing scheme; and the Gayno–Seaman PBL, a turbulent kinetic energy (TKE)-based eddy diffusion scheme. No FDDA was applied within the PBL to evaluate the ability of the two schemes to reproduce the PBL structure and its temporal variation. The restriction of the application of FDDA to the atmosphere above the PBL or the lowest 8 model levels, whichever is higher, has significantly improved the predicted strength and timing of the LLJ during the night. A systematic analysis of the PBL evolution has been performed for the primary meteorological fields (temperature, specific humidity, horizontal winds) and for the derived parameters such as the PBL height, virtual potential temperature, relative humidity, and cloud cover fraction. There are substantial differences between the PBL structures and evolutions simulated by these two different schemes. The model results were compared with independent observations (that were not used in FDDA) measured by aircraft, RASS and wind profiler, lidar, and tethered balloon platforms during the summer of 1999 as part of the NorthEast Oxidant and Particle Study (NE-OPS). The observations tend to support the non-local mixing mechanism better than the layer-to-layer eddy diffusion in the convective PBL. 相似文献
223.
Chevakidagarn P 《Environmental monitoring and assessment》2007,131(1-3):445-450
The study dealt with the method to predict the BOD5 in effluent from industrial wastewater by using the UV absorption from two wavelengths, 260 and 550 nm. The interference
from suspended solids was reduced. In the same time, COD was used as the secure value to calculate BOD5. From the representative wastewater treatment plants, the estimated effluent BOD5 of wastewater from the Para rubber industry showed an average error at ±2.97 mg/l. While it was at ±3.31 mg/l, for frozen
seafood industry. The simple mathematic equations in this study gave the assuring method for BOD5 estimation without time consuming. 相似文献
224.
This study compared three forecasting models based on the mean absolute percentage errors (MAPE) of their accuracy in forecasting
air pollution in a traffic tunnel: the Grey model (GM), the combination model used four sample point and five sample point
prediction with GM (1,1)(GM(1,1)4 + 5), and the modified grey model (MGM). An MGM was combined using the four points of the original sequence using the original
grey prediction GM (1,1) for short-term forecasting. The proposed method cannot only enhance the prediction accuracy of the
original grey model, but can also solve the jump data forecasting problem something for which the original grey model is inappropriate.
The MAPE was applied to the models, and the MGM found the proposed method to be simple and efficient. The MAPE of MGM, calculated
over 3 h of forecasts, were as follows: 10.12 (Upwind), 10.07 (Middle) and 7.68 (Downwind) for CO; 10.79 (Upwind), 6.05 (Middle)
and 5.98 (Downwind) for NO
x
, and 11.67 (Upwind), 7.32 (Middle) and 4.56 (Downwind) for NMHC. The MGM model results reveal that the combined forecasts
can significantly decrease the overall forecasting error. Results of this demonstrate that MGM can accurately forecast air
pollution in the Kaohsiung Chung–Cheng Tunnel. 相似文献
225.
226.
Sophie S. Parker Gregory B. Pauly James Moore Naomi S. Fraga John J. Knapp Zachary Principe Brian V. Brown John M. Randall Brian S. Cohen Thomas A. Wake 《Conservation biology》2018,32(5):1007-1019
When conservation strategies require new, field‐based information, practitioners must find the best ways to rapidly deliver high‐quality survey data. To address this challenge, several rapid‐assessment approaches have been developed since the early 1990s. These typically involve large areas, take many months to complete, and are not appropriate when conservation‐relevant survey data are urgently needed for a specific locale. In contrast, bioblitzes are designed for quick collection of site‐specific survey data. Although bioblitzes are commonly used to achieve educational or public‐engagement goals, conservation practitioners are increasingly using a modified bioblitz approach to generate conservation‐relevant data while simultaneously enhancing research capacity and building working partnerships focused on conservation concerns. We term these modified events expert bioblitzes. Several expert bioblitzes have taken place on lands of conservation concern in Southern California and have involved collaborative efforts of government agencies, nonprofit organizations, botanic gardens, museums, and universities. The results of expert bioblitzes directly informed on‐the‐ground conservation and decision‐making; increased capacity for rapid deployment of expert bioblitzes in the future; and fostered collaboration and communication among taxonomically and institutionally diverse experts. As research and conservation funding becomes increasingly scarce, expert bioblitzes can play an increasingly important role in biodiversity conservation. 相似文献
227.
Time discounting and the decision to protect areas that are near and threatened or remote and cheap to acquire
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Paul R. Armsworth 《Conservation biology》2018,32(5):1063-1073
Should conservation organizations focus on protecting habitats that are at imminent risk of being converted but are expensive or more remote areas that are less immediately threatened but where a large amount of land can be set aside? Variants of this trade‐off commonly arise in spatial planning. I used models of land‐use change near a deforestation frontier to examine this trade‐off. The optimal choice of where to protect was determined by how decisions taken today accounted for ecological benefits and economic costs of conservation actions that would occur sometime in the future. I used an ecological and economic discount rate to weight these benefits and costs. A large economic discount rate favored protecting more remote areas, whereas a large, positive ecological discount rate favored protecting habitat near the current deforestation frontier. The decision over where to protect was also affected by the influence economic factors had on landowners' decisions, the rate of technological change, and ecological heterogeneity of the landscape. How benefits and costs through time are accounted for warrants careful consideration when specifying conservation objectives. It may provide a niche axis along which conservation organizations differentiate themselves when competing for donor funding or other support. 相似文献
228.
The microbial strain Azotobacter vinelandii UWD was grown under conditions of simulated microgravity in the National Aeronautics and Space Administration (NASA) Bioreactor. Bacterial growth in simulated microgravity differed significantly from that observed in conventional shake flask experiments: Cells tended to grow in a cluster-like pattern and polymer production started immediately after exposing them to conditions of simulated microgravity, and no lag time was observed. It was imperative to differentiate between the effects derived from microgravity and those imposed by the altered oxygen supply in the bioreactor. Aeration conditions were studied in both reactor types and a gas supply profile was developed for the bioreactor. This supply profile allowed for similar amounts of dissolved oxygen in the bioreactor and the shake flask in the initial stage of the fermentation and, therefore, for an evaluation of the effects of microgravity on biopolyester-producing bacteria. Since the optical density that is conventionally used as a measure for the cell growth could not be used due to the cluster-like growth pattern of the cells, it was determined that bacterial growth behavior in the bioreactor can be monitored through glucose or oxygen consumption. 相似文献
229.
酵母菌与两种硫杆菌复合对污泥中三价铬的去除 总被引:6,自引:0,他引:6
研究了氧化亚铁硫杆菌LX5(Thiobacillus ferrooxidans LX5)、氧化硫硫杆菌TS6(Thiobacillus thiooxidans TS6)和耐酸性酵母菌R30(Rhodotorula sp.R30)对重金属铬(Cr3+)的耐受性.结果表明,700mg/L的Cr3+对硫杆菌LX5、TS6的生长和氧化活性影响不大,但Cr3+浓度大于500mg/L时明显抑制酵母菌R30的生长.酵母菌R30与硫杆菌LX5和TS6复合能明显加速污泥淋滤的进程,最佳复合比为酵母菌R30接种量2.0%,硫杆菌LX5和TS6接种量10%.分别用含酵母菌R30数量为104个/mL和102个/mL的酸化污泥作接种物进行污泥淋滤,发现淋滤过程中pH值下降的速度没有明显差异,而在淋滤起始时添加2.0%的酵母菌R30,则淋滤反应提前36h结束.由此可见,在其它条件相同的污泥淋滤中,污泥中所含耐酸性酵母菌的数量是加快淋滤的关键. 相似文献
230.
Konstantinos M. Kasiotis 《毒物与环境化学》2017,99(4):578-589
5-Hydroxymethylfurfural is found in several food commodities, including honey. Its concentration is used as one of honey's quality indicators since elevated 5-hydroxymethylfurfural levels indicate overheating and aging of the product. In this context, the European Commission and Codex Alimentarius established the maximum tolerable level for 5-hydroxymethylfurfural, for general type honeys intended for human consumption, at 40 mg kg?1. In this study, 5-hydroxymethylfurfural, 2-furfural, and the furfuralic derivative 5-methyl-2-furfural were investigated in Greek honey samples, through a high performance liquid chromatographic photo diode array mass spectrometric method developed and validated. Sample preparation was based on a modification of the ‘Quick, Easy, Cheap, Effective, Rugged, and Safe’ procedure. The method was sensitive, exhibiting limit of detection for 5-hydroxymethylfurfural at 0.1 mg kg?1, far below the permissible level of 40 mg kg?1. Levels of 5-hydroxymethylfurfural in 28 honey samples varied from 0.5 to 23.5 mg kg?1, thus, not worrying for consumers. Traces of 2-furfural were detected in limited samples. 相似文献