New best estimates for radionuclide solid–liquid distribution coefficients in soils. Part 2. Naturally occurring radionuclides

Predicting the transfer of radionuclides in the environment for normal release, accidental, disposal or remediation scenarios in order to assess exposure requires the availability of an important number of generic parameter values. One of the key parameters in environmental assessment is the solid liquid distribution coefficient, K_d, which is used to predict radionuclide–soil interaction and subsequent radionuclide transport in the soil column. This article presents a review of K_d values for uranium, radium, lead, polonium and thorium based on an extensive literature survey, including recent publications. The K_d estimates were presented per soil groups defined by their texture and organic matter content (Sand, Loam, Clay and Organic), although the texture class seemed not to significantly affect K_d. Where relevant, other K_d classification systems are proposed and correlations with soil parameters are highlighted. The K_d values obtained in this compilation are compared with earlier review data.     

我国能源消费需求的时变弹性分析

为了科学分析相关经济因素变化对我国能源需求的影响效应,本文在提取能源消费需求主要影响因素的基础上,建立了基于Bayesian理论的时变系数回归模型,利用MCMC方法获得了各时变回归系数的估计.同时,利用HP滤波方法,得到了能源消费需求相对于各相关因素弹性系数的趋势及波动情况,并就能源需求对各相关经济因素弹性系数的趋势变动原因进行了分析,结果表明:①在不同的时间段内,能源价格、产业结构、经济增长、全国总人口以及能源消耗结构对能源消费需求的影响强度具有时变效应;②电力价格变动对降低能源消费的作用最为显著,但边际效应在逐年下降;煤炭价格的提高对能源消费的增加具有很大推进作用,但"煤电联动"、能源价格市场化的建设可能进一步抑制能源需求;③城镇化建设进程可进一步优化人口结构、产业结构以及能源消费结构,这将在很大程度上限制能源需求的加速增长.     

农村低保救助水平的评估

农村最低生活保障制度在中国范围内已经实现制度覆盖,自2007年制度全面推行以来,由于各省市财政对农村低保救助力度强弱差异,导致了对农村低保对象的救助程度存在很大的差异性.但由于这种差异性受很多因素如价格指数等经济指标的影响,存在着不可比性.笔者通过引入农村低保救助力度系数和生活救助系数剔除这种差异性,从横向和纵向的视角对中国现行农村低保制度的救助水平进行了评估.评估的结果发现,各地的农村低保标准相差较大,经济发达地区剔除经济发展水平等因素以后,保障标准仍然要高于经济相对落后中西部农村地区(上海市除外).所以,建议这部分省市的民政部门要根据本地的经济发展水平来制定当地农村低保名义标准,从而保证当地农村低保居民享受到的实际福利至少不应该低于低保名义标准.     

基于农业用地和地形约束的陇南山区适宜人口规模估算

陇南山区地形复杂,耕地不足,经济贫困,人口对资源环境的压力较大。研究适度人口容量对于地震灾后重建、缓解贫困以及保护长江上游的生态安全具有重要意义。以人均粮食和经济水平两个指标来估算温饱、宽裕和小康3个水平上的人口承载量,测度人口和农业资源的关系。并基于地形复杂度计算劳动用工及可抚养人口。结果表明:目前陇南10县(区)的人口在温饱生活水平下尚有超载。以小康生活为标准,适宜人口规模约为135万。经营现有的农耕地和林地需要100.81万劳动力,可抚养人口191.54万人,加上城镇人口总人口为231.03万。这个人口规模实现温饱有余而宽裕不足,难达小康目标。"人口-农业用地-劳动力"之间形成了一个怪圈,决定了陇南山区农村实现小康目标的艰巨性和复杂性。为此,陇南山区的灾后重建和区域可持续发展需要创新思路,多方并举。     

几种倒伞型表面曝气机的充氧性能

对安徽某科技公司产自行研究的几种倒伞型表面曝气器的充氧性能进行模拟比较研究,利用合肥某氧化沟装置在清水条件下对各叶轮的氧总转移系数KLa、理论充氧能力qc、理论动力效率E及水体流速v进行了测试,对比分析了叶片安装角度、片数及叶片设计对充氧能力的影响。结果表明,叶片导流辐板斜角设计对充氧效率影响最大,是叶轮性能提升最关键因素。     

统计分析方法在大气环境监测数据符合性分析中的应用探讨

通过汇总分析气井的试气环境监测数据,选择AERMOD模式,运用EIAProA软件模拟预测试气SO2浓度,对实测和预测数据进行F检验和t检验,验证其方差是否符合显著性要求,同时检验其相关系数、系统均方差和非系统均方差,结果表明符合指数,满足论文预设的70%的要求。     

Carbaryl, 2,4-D,and Triclopyr Adsorption in Thatch-Soil Ecosystems

Thatch development in intensively managed turf sites may cause environmental concerns for greater sorption or leaching of applied chemicals in terrestrial ecosystems. To determine the adsorption potential of Carbaryl (1-Napthyl N-methylcarbamate), 2,4-D (2,4-dichloro-phenoxyacetic acid), and Triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) in turf ecosystems, composite thatch and underlying soil samples from three- and six-year-old stands of cool-season Southshore creeping bentgrass (Agrostis palustris Huds.) and warm-season Meyer zoysiagrass (Zoysia japonica Steud.) were collected. The samples were processed and analyzed for total organic carbon (C_Org); extractable (C_Ext), humic (C_HA) and fulvic acid (C_FA); anthrone reactive nonhumic carbon (ARC) fractions; and C_HA and C_FA associated iron (Fe) contents. Pesticide adsorption capacity (K _f ) and intensity (1/n), organic carbon partition coefficient (K _OC ) and Gibbs free energy change (Δ G) were calculated for thatch materials and the underlying soils using a modified batch/flow technique. Both bentgrass (BT) and zoysiagrass thatch (ZT) contained a greater concentration of C_Ext, C_FA, C_HA, and ARC than the respective soils (BS and ZS). The C_Ext, C_FA, C_HA, and ARC concentration was higher in BT compared with ZT. The BT contained a greater concentration of bound Fe in both C_FA and C_HA fractions than in BS, whereas ZT had more bound Fe in C_HA fraction than in ZS. On average, the BT had a greater concentration of bound Fe in C_Ext, C_FA, and C_HA fractions than in the ZT. Among the pesticides, Carbaryl had higher K _f and 1/n values than 2,4-D and Triclopyr for both thatch and soil. Although the K _OC and Δ G values of Carbaryl were higher in both BT and ZT than in the underlying soils, the K _OC and Δ G values of 2,4-D were significantly higher in BS and ZS than in the overlying thatch materials. The 2,4-D and Triclopyr had higher leaching indices (LI) than Carbaryl for both BT and ZT materials than the respective soils. The Carbaryl, however, had a higher LI for soils than for thatch materials. Averaged across thatch materials and soils, C_Org accounted for 96, 85, and 84% variations in Carbaryl, 2,4-D, and Triclopyr adsorption, respectively. Among the C_Org fractions, lignin followed by C_FA and C_HA accounted for greater adsorption of pesticides, especially Carbaryl. The concentration of C_HA and C_FA bound Fe did not correlate with K _f and 1/n values of pesticides.     

The effects of sinusoidal leading edge of turbine blades on the power coefficient of horizontal-axis wind turbine (HAWT)

In order to improve the aerodynamic performance of horizontal-axis wind turbine (HAWT), a sinusoidal shape is applied to turbine blade. In this study, four types of modified blades were chosen based on variations in amplitude and wavelength of protuberance along the leading edge. Compared with the baseline model, the power coefficients (C_p) of HAWT with modified blades were improved, especially at low tip speed ratios. At low wind speed (V = 6 m/s), blades with short wavelength obtain significant improvement in C_p compared with the baseline model. As wind speed increases, this improvement decreases. In addition, turbine blade with large amplitude and long wavelength obtains better C_p values at higher wind speeds than lower ones, which have a great potential to be more superior at relatively higher wind speeds.     

工业火炬气NOx排放的模拟实验

为准确核定石化企业火炬气NO_x的排放情况,采用模拟火炬燃烧装置对现场采集的不同种类火炬气进行燃烧,取得了燃烧温度及NO_x排放数据。实验结果表明：火炬气的燃烧温度及燃烧烟气中的NO_x质量浓度与火炬气组分中H₂的体积分数呈正相关;兰炭荒煤气、煤甲醇合成驰放气、合成氨变换气和合成氨合成解析气的燃烧温度分别为410,430,560,650℃。通过计算得到4种火炬气的NO_x排放系数分别为：合成氨合成解析气0.3154~0.5406kg/t,煤甲醇合成驰放气0.1245~0.2263kg/t,合成氨变换气0.0591~0.0813kg/t,兰炭荒煤气0.0801~0.1762kg/t。     

Numerical Modeling of Particulate Matter Dispersion from Kerman Cement Plant, Iran

A three dimensional diffusion model has been developed for computing the concentration of PM10 from Kerman Cement Plant, Iran. This model incorporates source-related factors, meteorological factors, surface roughness, and settling particles to estimate pollutant concentration from continuous sources. The study focused on the local environmental impact of Kerman Cement Plant. The performance of the model was found to be in good agreement with measured data; the average absolute percent deviation is 25.53%. In addition, the result of this modeling shows that the PM10 concentration in the ambient air at distances of about 600–1,400 m from the stacks is higher than the WHO guidelines of an annual average of 260 μg/m³.