Accumulation of Heavy Metals by Chickpea Grown in Fly Ash Treated Soil: Effect on Antioxidants

Chickpea grown in fly ash (FA) treated soil (25, 50, and 100% FA) was used to evaluate the effect of FA on antioxidants, metal concentration (Fe, Zn, Cu, Cr, and Cd), photosynthetic pigments (chlorophyll a (chl‐a), chlorophyll b (chl‐b), total chlorophyll (total chl), and carotenoids), growth and yield performance. All antioxidants in roots, shoots and leaves of chickpea increase with increasing FA doses to combat FA stress. The activities of antioxidants were more in the root tissues to cope with stress induced in the plants as compared to shoot and leaf. Concentration of metals was found maximum in roots than the shoots and seeds. The highest concentration of Fe and lowest level of Cd were recorded in all treatments of FA for different parts of the plant. The treated crop showed reduced level of chlorophyll but enhanced level of carotenoids and protein. However, root length, number of nodules and biomass in 25 and 50% FA treatments did not differ significantly in comparison to respective control plants. These results suggest that heavy metals of FA causes oxidative stress in this crop and the antioxidant enzymes could help a pivotal role against oxidative injury.     

Water-ice clouds and dust in the north polar region of Mars using MGS TES data

Water-ice and dust optical depths in Mars’ north polar region are mapped as function of season, latitude and longitude, and their characteristics and variability on a geographic, seasonal, and interannual basis are discussed. We use water-ice and dust optical depth data provided by the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES), covering nearly three northern spring and summer periods. We find that interannual variability exists in both the water ice and dust behavior, although there are trends that repeat year to year as well. The optical thickness of the north polar hood (NPH) exhibits interannually varying longitudinal structure, both during springtime recession and late-summer onset. We define the characteristics associated with the transition to and from the NPH and find that the disappearance occurs near L_s=75° and the reappearance near L_s=160-165°. We find that the late spring to early summer time frame is characterized by very low water-ice optical depths and enhanced dust activity, with a preference for lower water-ice and higher dust optical depths in the 0-90°W quadrant. We see possible evidence for stationary wavenumber 2 systems in a few of the maps examined.     

2020年春季中国北方一次扬沙天气过程微气象学与沙尘输送特征

利用内蒙古科尔沁沙地和沈阳地区同步气象要素梯度观测和地面大气颗粒物(PM_2.5和PM₁₀)质量浓度观测资料,分析了中国北方地区2020年5月10日一次大范围扬沙天气过程微气象学和沙尘输送特征。结果表明：受大尺度天气系统影响,此次沙尘天气过程中科尔沁沙地不同高度(<20 m)风速均明显增加,各层相对湿度和浅层地表含水量有所降低,较强湍流动力作用配合干燥的土壤和大气环境有利于沙源地区地表大量的沙尘粒子释放到大气中。此后这些沙尘粒子随较强的西北气流集中在2—3 km以下高度向下游地区输送。受沙尘输送的影响,沈阳地区10日小时平均PM₁₀浓度最高达817μg·m^-3,能见度减小至3.7 km。此外,科尔沁沙地起沙过程中能见度与摩擦速度存在明显的反相关关系(相关系数R²=0.93),与湍流动力学热通量相关性相对较小,表明湍流动力作用在此次起沙过程占主导作用。     

民勤一次沙尘暴的观测分析

给出了2004年5月23~24日民勤站爆发沙尘暴前后以及沙尘暴内部的温度、比湿和风速垂直廓线,分析了沙尘暴发生前后及沙尘暴期间高空气象要素的演变特征,同时对大气的热力、动力稳定度参数进行了计算和分析。结果表明:沙尘暴来临前边界层内具有深厚的混合层,大气层结处于不稳定状态,温、湿结构及风的垂直分布有利于沙尘暴的发生、发展;沙尘暴发生期,出现了稳定与不稳定层相间的情形,对流减弱,抑制了沙尘暴的发展;沙尘暴天气结束后中低层大气湿度增加显著;沙尘暴的强度与相对风暴螺旋度具有良好的对应关系。     

稀疏植被下垫面与大气相互作用研究进展

介绍了国家自然科学基金委员会“十五”重点项目“稀疏植被下垫面与大气相互作用研究”的成果。通过资料分析、数值试验和理论分析。研究干旱地区稀疏植被复杂下垫面上水、热及CO2输运过程的机理;非均匀下垫面的复杂非线性线效应：干旱地区更合理的陆面过程参数化方案以及绿洲的稳定性;强沙尘暴的发展机制和干旱地区生态环境建设对策,主要结果表明：（1）揭示了植物生态生理过程、净第一生产力和生物量对气候的敏感性,为稀疏植被下垫面与大气相互作用研究提供了较好的接口。（2）发展了适用于干旱、半干旱地区土壤中水热输送交叉耦合的物理模型;以能量和物质守恒定律为基础的雪盖物理模型,它显著地改善了陆面过程的模拟效果,是国际上最早开发的同类模型之一。（3）发展了大气非平衡态热力学,证明了非线性区普遍成立的最小熵产生原理,为研究气候和环境复杂系统提供了新思路和新方法;提示了大气辐散和辐合运动对垂直湍流输送的影响,非均匀下垫面地气相互作用,为非均匀下垫面陆面过程参数化提供了物理基础;研究了绿洲稳定性并估算了绿洲临界尺度约3～6km,为绿洲保护和建设提供了理论依据;提出了干旱地区有限水资源条件下增强其稳定性抗干扰能力的生态环境建设对策。（4）发展了强沙尘暴发展的动力学模式,揭示了强沙尘暴发展辐射冷却的正反馈机制。展示了强沙尘暴预报的良好前景。     

内蒙古科尔沁沙地临界起沙阈值的范围确定

临界起沙阈值可表征地表土壤的可蚀性,是风蚀起沙研究中非常重要的物理量之一。基于微气象学方法,将沙尘浓度和垂直沙尘通量均开始增加且至少持续0.5 h所对应的摩擦速度(或风速)确定为临界起沙摩擦速度u_*t(或临界起沙风速U_t)。利用内蒙古科尔沁沙地地区2010-2013年春季大气环境综合观测资料,分析了不同沙尘天气过程(扬沙、沙尘暴和强沙尘暴)起沙阶段沙尘浓度和垂直沙尘通量随摩擦速度的演变特征,精细确定了该地区临界起沙摩擦速度(u_*t)和临界起沙风速(U_t)的范围分别为0.45±0.20和6.5±3.0 m/s,同时讨论了不同起沙判据对确定临界起沙阈值产生的影响。相比而言,采用的起沙判据尽可能地排除了沙尘输送和沉降过程的影响,适用于不同的沙尘天气类型,使沙尘粒子进入大气的起沙结果更趋于合理,其结果可为建立统一、合理的起沙判据提供参考。     

Detection of Sahara dust intrusions during mixed advection patterns over south-east Italy: A case study

Measurements from July 4 to July 8, 2005 by a high resolution visible radiometer, a Raman lidar, a ground particulate matter sampler, and ground meteorological sensors have been combined in synergy to infer the intrusion over south-east Italy, of air masses from north-west Sahara, the Atlantic Ocean, and the continental Europe. It is shown that backscatter coefficient, depolarization-ratio, and lidar ratio vertical profiles represent the best tools to detect the intrusion of long range transported air masses and to monitor their effects on the vertical distribution of aerosol optical and microphysical properties. High resolution radiometers are instead important tools to monitor changes on columnar aerosol properties and size distributions.Backscatter coefficient, depolarization-ratio, and lidar ratio vertical profiles have revealed that aerosol optical and microphysical properties significantly changed with time and space during African dust outbreaks: the intrusion of dust particles that at first occurred above 2 km of altitude extending up to 6 km, affected the all aerosol load down to ground within few hours. Aerosol size distributions showed during dust events a clear bimodality with an accumulation mode maximum at 0.24 µm and a coarse mode maximum at 0.94 μm. Conversely, we have found that during the advection of air masses from the Atlantic and continental Europe, aerosol particles were mainly located below 2 km, their optical and microphysical properties were affected by smaller changes in time and space, and were characterized by depolarization ratios rather close to those due to a pure molecular atmosphere. In this case bimodal size distributions with an accumulation mode showing two sub-modes at 0.16 μm and 0.24 μm, respectively and a coarse mode centred at 0.94 μm have also been observed.     

２种统计方法对气象要素均一性的影响

在天气现象观测中,轻雾、霾、浮尘是较易混淆的天气现象,准确的判断和记录这些现象,需要从形成条件、天气背景、垂直能见度、相对湿度等方面进行分析,综合判断,本文对此作了一些分析和探讨。     

中国地区沙尘气溶胶输送过程的数值模拟

本文建立了一个包含沙尘起沙、输送、干沉积和湿沉积过程的气溶胶输送扩散模式．并和中尺度气候模式RIEMS相连接研究了1998年1月、4月、7月和1997年10月的沙尘起沙、输送、干沉积和湿沉积的过程。计算1998年1月、4月、7月和1997年10月气溶胶浓度及其分布．并和这四个月份的平均起沙分布以及北京、郑州和南京的实例沙尘分布作了比较．结果表明我国起沙多发生在春季．同时春季也是我国沙尘强度最大的季节。沙尘在我国西北的沙地和沙漠地区起沙后．向我国的东南方向输送．在输送过程中沙尘浓度逐渐降低。     

内蒙古“4．23”沙尘暴天气的环流背景及成因

利用常规观测资料和MICAPS提供的相关资料,对2009年4月23日－24日在内蒙古中西部地区发生的大范围大风、沙尘暴天气的高、低空环流形势、物理量场、卫星云图及数值预报场进行了分析。结果表明：a）本次沙尘暴的主要影响系统是贝加尔湖高空低涡引导冷空气南下在蒙古形成密集的高空锋区;b）地面蒙古气旋的暖性性质为沙尘暴的爆发提供了有利的热力条件;c）强烈的上升与下沉运动为大风、沙尘天气的发生提供了动力条件;d）螺旋状逗点云系的发展为此次大风、沙尘暴天气的形成提供了有利条件;e）沙尘暴发生前期上游地区干暖的气候条件及下垫面增厚的于土层及沙区,对沙尘暴的发生提供最基本的环境条件。