城市地表系统POPs多介质循环过程与模拟研究进展

城市地表系统(USS)是陆地表层系统的重要组成部分,而以不透水面覆盖为主要特征的城市土地利用/覆被变化(LUCC)时空过程,打破了系统原有自然地理格局与过程,影响不同介质和界面间的物质循环与能量流动,改变POPs等污染物的循环过程与机理,是城市环境变化和人地相互作用的指示器与重要驱动力,是城市生态环境规划与管理保护的关键依据.本文总结了城市LUCC对POPs多介质分布迁移的影响,包括单介质中POPs的时空分布特征和POPs多介质迁移累积过程;从城市POPs多介质归趋模拟和基于GIS的城市多介质归趋模拟等方面,讨论了城市POPs多介质循环过程归趋模拟的主要进展;展望今后研究中需要重点解决的科学问题:基于不透水面的城市LUCC信息精确提取及与POPs排放输入等相关数据的同化集成; POPs多介质多界面迁移、转化过程与城市LUCC的耦合机理;城市LUCC背景下POPs循环过程、机制的关键模型参数的构建与获取;基于GIS和城市POPs循环过程与机理的、具有高时空分辨率的城市多介质归趋模型(UMFM)的构建与应用.     

垃圾填埋场微生物气溶胶粒径分布研究

为了了解垃圾填埋场微生物气溶胶粒径分布规律,在北京市某垃圾卫生填埋场填埋区、渗滤液处理区、生活区分别选定监测点,利用安德森六级微生物采样器,对填埋场空气微生物进行了系统的定点取样、测定和分析。研究结果表明,空气细菌粒径分布均为第Ⅰ级(>8.2 μm)最高,填埋区空气细菌粒径呈偏态分布,渗滤液处理区、生活区分别在第Ⅳ级和第Ⅲ级出现第2个峰值。携带细菌的可吸入微粒在渗滤液处理区比例最大。空气真菌与放线菌均在第Ⅳ级分布最高,携带真菌和放线菌的可吸入粒子的比例显著大于细菌(P<0.05)。填埋区不同作业时段空气微生物粒径在各级分布比例基本一致。填埋区细菌气溶胶中值直径为5.7 μm,渗滤液处理区为3.7 μm,生活区为5.3 μm,显著大于真菌气溶胶和放线菌气溶胶的中值直径(P<0.05)。     

柠檬酸对核电站低放废液中110mAg吸附去除性能的影响

具有γ放射性的~(110m)Ag是核电站放射性废液中的主要核素之一,半衰期长,并且可以通过食物链在海洋生物中富集,研究其高效去除技术具有重要的意义.核电站化学去污过程加入的络合剂(如柠檬酸)对~(110m)Ag的化学形态和吸附性能有重要的影响.因此,本文首先模拟核电站水化学环境,研究了柠檬酸对~(110m)Ag化学形态的影响规律,其次研究了不同形态的~(110m)Ag物种在几种优选材料上的吸附性能.结果表明,由于核电站放射性废液的来源不同,柠檬酸与~(110m)Ag同时形成离子态络合物和~(110m)Ag0/柠檬酸纳米金属复合物;采用过氧化氢与紫外线联合高级氧化的方法能够破坏柠檬酸络合离子及~(110m)Ag0/柠檬酸复合物结构,形成单独的离子态~(110m)Ag+,从而有效地提高了~(110m)Ag物种的吸附去除性能.     

基于Landsat数据的关中盆地腹地AOD时空格局及城市化对其影响

气溶胶光学厚度(aerosol optical depth,AOD)是气溶胶最基本的光学特性之一,表征气溶胶对光的消减作用,对区域大气污染有一定的指示作用.首先,以2000 ～ 2019年长时间序列MOD09A1产品数据为基础,利用ASTER波谱数据库,构建了Landsat TM/OLI蓝光波段地表反射率数据集,利用深...     

近3年西双版纳州勐腊县大气污染基本特征及污染原因分析

对西双版纳州生态环境局勐腊分局2017年8月-2020年8月逐日空气质量数据的分析表明,2-4月是勐腊县空气质量指数（Air Quality Index,AQI）频繁达到二级及以上的时段,空气质量分指数（Individual Air Quality Index,IAQI）能够达到二级及以上标准的污染物为PM_2.5、PM₁₀、O₃、SO₂中的一种或几种,PM_2.5、PM₁₀污染较为严重,PM_2.5对空气质量的影响最大,可使空气质量达到重度污染,混合污染出现比例远大于单一污染.2019、2020年3-4月勐腊县轻度及以上连续污染日数超过5 d的5次过程中,4次污染过程的主要潜在源区在勐腊上风方向老挝西北部及泰国与其相邻的区域,权重潜在源贡献因子（Weight Potential Source Contribution Function,WPSCF）大于0.6的区域与同年3、4月泰国西北部、老挝西北部的火点密集区有较好的对应关系,4次污染过程与老挝西北部及泰国与其相邻区域的生物质燃烧关系密切;1次污染过程的主要潜在源区主要在当地,当地建筑施工、交通运输、生物质燃烧和餐饮行业细颗粒物的排放会导致勐腊县空气质量出现明显下降.为验证勐腊县连续污染过程受到了周边国家烧荒的影响,利用逐日气溶胶光学厚度（Aerosol Optical Thickness,AOT）对2020年3月23-4月9日的污染过程进行了个例分析,发现AOT大值区位于勐腊上风方向,高浓度污染物持续稳定地向勐腊传输导致勐腊出现持续重污染.     

BAYESIAN MODELS OF FORECASTED TIME SERIES1

Bayesian Processor of Forecasts (BPF) combines a prior distribution, which describes the natural uncertainty about the realization of a hydrologic process, with a likelihood function, which describes the uncertainty in categorical forecasts of that process, and outputs a posterior distribution of the process, conditional upon the forecasts. The posterior distribution provides a means of incorporating uncertain forecasts into optimal decision models. We present fundamentals of building BPF for time series. They include a general formulation, stochastic independence assumptions and their interpretation, computationally tractable models for forecasts of an independent process and a first-order Markov process, and parametric representations for normal-linear processes. An example is shown of an application to the annual time series of seasonal snowmelt runoff volume forecasts.     

PARAMETRIC ESTIMATION OF COVARIANCES OF REGIONALIZED VARIABLES1

ABSTRACT: The usefulness of stochastic models in describing the spatial variability of hydrogeologic quantities, such as permeability, storativity, piezometric head, seepage velocity, and solute concentrations is now widely recognized. In practice, these quantities are represented as the sum of a well-structured component, or drift, and a more erratic fluctuation component which is described statistically through its covariance function. This paper reviews some of the most recent and most promising methods for the estimation of parameters of these covariances from existing data. They are maximum likelihood, restricted maximum likelihood, minimum-variance unbiased quadratic estimation, and minimum-norm (weighted least squares) estimation. The applicability of such methods to conditional and unconditional probability problems is discussed.     

Metals recycling in the United States

Twenty-two metals for which secondary recovery is important, in terms of quantity and/or value, were compared and ranked for rate and efficiency of recycling, and availability of recycled metal. In general, their recycling rates trended upward over the period 1970–1993. Iron, aluminum, copper, gold, platinum, and lead accounted for most of the value of all secondary metal produced, while iron and steel dominated in terms of quantity produced and exported. The factors most influential on recycling rates are profitability, public support, organization of infrastructure, sortability, legislative support, and scrap purity. The share of supply accounted for by secondary metals is expected to surpass that of primary metals sometime in the next decade.     

Sensitivity of Ozone Production to the Nmhc Composition, Aerosol Back-Scattering and High Chimney Emission

In this paper, three sensitivity studies are designed to analyze the effect of the NMHC (Non-Methane HydroCarbon) composition, the aerosol back-scattering and the high chimney NO_x emission to the photochemical prodution of ozone by using a one-dimensional photochemistry-diffusion model under a favourable meteorological condition. Measurements of the NMHC composition in Taipei indicated that the percentage of iso-butene, cis-2-butene, trans-2-butene and benzene in a unit volume was much higher than of those observed in other major cities. the high ratio of benzene was directly linked to its high percentage in gasoline. As to the unusually high amount of iso-butene, cis-2-butene and trans-2-butene, more researches are needed to identify their source. Concerns are raised as to how productive is NMHC composition is to the photochemical production of the surface ozone. A rough estimate shows that the total reactivity of the Taipei NMHC composition is about 1.21 × 10^-9 cm³ s^-1 which is 1.6 times that of the Los Angeles (LA) NMHC composition, while the simulated noon peak will be different by 28 ppbv, i.e. 18% more than that simulated with a LA composition.

Meanwhile, high aerosol loading is a serious problem in Taipei. the attenuation of the UV radiation by aerosols cannot be ignored. A numerical simulation shows that the noon ozone level will decrease from 178 to 141ppbv, i. e. about 21% reduction, with deterioration of the visual range from 85 to 5 km.

In the southern Taiwan, industry parks are mixed with the populated Kaohsiung city, hence the large emission of NO_x from high chimneys cannot be ignored. in this study, NO_x is assumed to be emitted in the layer between 235-460 m high with an emission rate of 0.05 or 0.145 ppbv/sec. the results show that the NO_x emitted from the elevated stack lead to a considerable reduction of surface ozone. Such conclusion is obtained due to the fact that a one-dimensional model is used in this paper. Whereas, if a three-dimensional regional model was used, then a higher productivity of ozone downstream would be simulated.     

Simulation of Live and Dead Phytomass Formation and Transformation in Optimized Agrocenoses

The formation and transformation of live and dead phytomass in agrocenoses with a complex horizontal structure are described. These processes are demonstrated to be specific and to be determined by differences in the horizontal structure. Only agrocenoses of a mosaic structure (with square parcels) have optimal conditions for these processes.