密闭空间药雾浓度测量的试验方法研究   总被引：1，自引：3，他引：1  

邱白晶  吴昊  汤伯敏  梁建  沙俊炎 《农业工程学报》2007,23(12):18-23

运用改进后的大气采样器，建立了一种对密闭空间细雾流分批采样分批分析的研究方法。对于采样参数组合的选取以及双侧采样的空间差异性进行了研究和统计判断，得出了最佳采样参数组合为采样时间5min，采气量5L／min。基于最佳采样参数组合，发现沉降曲线中存在分段点现象，分段点在喷雾结束后13min，也即开始喷雾后27min附近。针对分段点现象，给出了分段拟合的细雾流浓度沉降曲线及解析描述。采用改进的大气采样器可以获取喷雾结束后79rnin内的浓度数据，文献[13]中所用的采样方法只能得到喷雾结束后45min左右的浓度数据，因此该方法对药雾浓度沉降曲线的尾部特征描述能提供更多的信息。  相似文献   

Effect of acid rain on sandstone: The Royal Palace and the Riddarholm church,Stockholm     

A. G. Nord  K. Tronner 《Water, air, and soil pollution》1995,85(4):2719-2724

The deterioration of two kinds of sandstone is discussed for two 18:th century buildings in central Stockholm: the Royal Palace, and the Royal Carolean Burial Chapel (Karolinska gravkoret) annexed to the mediaeval Riddarholm church. The facades of calcitic Gotland sandstone show many signs of serious decay, such as gypsum formation, pulverized surface, exfoliation, discolouration, and salt efflorescence. The socles are built of the more resistant quartzitic Roslagen sandstone, displaying some discolouration, cracks, and slight exfoliation. In total about 300 samples have been analysed. The surface concentration of sulphur is highest at ground level and at rain-sheltered positions. Chemical and sulphur isotope data indicate that the stone decay to a large part may be attributed to anthropogenic sources like acid deposition and car traffic.  相似文献   

An analysis of wet deposition of sulfate using a trajectory model for East Asia     

Y. Ichikawa  S. Fujita 《Water, air, and soil pollution》1995,85(4):1927-1932

A long-range transport model for East Asia was developed to estimate the wet deposition of sulfate. The model is a trajectory type which is appropriate for long-term analysis. Trajectories of air masses are calculated by tracing the wind field which changes spatially and temporally. The processes of reactions, rainout removal, intake of sulfate in cloud water into rain water, and dry and wet depositions are considered. It is possible to calculate the concentration of sulfate in precipitation at a receptor by performing material balance in a grid box containing the receptor.The results obtained by the long-range transport model were evaluated through comparison with observation data of acidic deposition. The observation was conducted at 21 stations throughout Japan for one year. The calculated amount of wet deposition of sulfate in Japan was 0.22Tg/y in S equivalent, while the observed amount was 0.29Tg/y. The long-range transport model can predict almost 80% of observed wet deposition. The contributions of domestic anthropogenic sources and volcanic eruption to wet deposition of sulfate in Japan were estimated using the longrange transport model. The ratio of the deposition of sulfate due to Japanese anthropogenic sources to that due to the Asian continental sources was about 1 to 2. Since air stream from the direction of the Asian continent dominates during winter, the contribution of Japan to wet deposition in the region which faces the Sea of Japan amounted to less than 15%. The contribution of the sulfur oxides from volcanoes was about 20%.  相似文献   

Nitrogen deposition and dissolved organic carbon production in northern temperate forests     

R.L Sinsabaugh  D.R Zak  C Lauber 《Soil biology & biochemistry》2004,36(9):1509-1515

Deposition of anthropogenic nitrogen (N) alters the decomposition of organic matter in forest ecosystems by changing the expression of key microbial enzymes. We investigated the effects of experimental N deposition on dissolved organic matter (DOM) in soils of three forest ecosystems representative of the upper Great Lakes region: the sugar maple/basswood (SMBW), sugar maple/red oak (SMRO) and white oak/black oak (WOBO) ecosystems. Mineral soil samples were collected on five dates from ambient and N-amended plots (80 kg N ha⁻¹ yr⁻¹) in three replicate stands of each forest type. DOM was extracted (2:1, water:soil) from each soil sample and analyzed for dissolved organic carbon (DOC). DOC concentration was significantly greater in the N-amended soils (on average: 24% higher for SMBW, 9% for SMRO, and 40% for BOWO). In June and October 2002, bioassays were performed to assess N treatment effects on the composition of DOM and its interacting bacterial community. Within each site, DOM extracts from the ambient and N-amended plots were reciprocally inoculated with bacteria from each plot. After a 48 h incubation at 20 °C, community activity in each microcosm was profiled by measuring 10 extracellular enzyme activities (EEA). MANOVA showed that ecosystem type, sampling date, DOM source (ambient or N-amended plot) and inoculum source (ambient or N-amended plot) all had significant effects on bioassay EEA. Post hoc tests (Tukey's HSD) found significant reductions in oxidative enzyme activity as a result of the N treatment. In general, the bioassay results corroborated a previous report describing losses in soil oxidative enzyme activity in response to N saturation. However, it is not clear whether increased DOC concentration is the direct result of reduced oxidative activity.  相似文献   

Laboratory study of SO2 dry deposition on limestone and marble: Effects of humidity and surface variables     

E. C. Spiker  R. P. Hosker Jr.  V. C. Weintraub  S. I. Sherwood 《Water, air, and soil pollution》1995,85(4):2679-2685

The dry deposition of gaseous air pollutants on stone and other materials is influenced by atmospheric processes and the chemical characteristics of the deposited gas species and of the specific receptor material. Previous studies have shown that relative humidity, surface moisture, and acid buffering capability of the receptor surface are very important factors. To better quantify this behavior, a special recirculating wind tunnel/environmental chamber was constructed, in which wind speed, turbulence, air temperature, relative humidity, and concentrations of several pollutants (SO₂, O₃, nitrogen oxides) can be held constant. An airfoil sample holder holds up to eight stone samples (3.8 cm in diameter and 1 cm thick) in nearly identical exposure conditions. SO₂ deposition on limestone was found to increase exponentially with increasing relative humidity (RH). Marble behaves similarly, but with a much lower deposition rate. Trends indicate there is little deposition below 20% RH on clean limestone and below 60% RH on clean marble. This large difference is due to the limestone's greater porosity, surface roughness, and effective surface area. These results indicate surface variables generally limit SO₂ deposition below about 70% RH on limestone and below at least 95% RH on marble. Aerodynamic variables generally limit deposition at higher relative humidity or when the surface is wet.  相似文献   

Use of fallout Cs in investigations of overbank sediment deposition on river floodplains     

D.E. Walling  Q. He 《CATENA》1997,29(3-4)

River floodplains have been recognised as important sinks for storing suspended sediment and associated contaminants mobilised from the upstream catchment. However, information on contemporary rates of overbank sedimentation is difficult to obtain using conventional methods. Measurements of the ¹³⁷Cs content of floodplain sediments provide an alternative approach to obtaining; estimates of medium-term rates (ca. 40 years) of overbank sediment deposition. The ¹³⁷Cs approach requires only a single site visit and minimum sample preparation. Furthermore, it is capable of providing information on spatial patterns of sediment deposition on floodplains, which is needed to improve our understanding of the processes involved in overbank flow and sediment deposition. This paper reviews the basis for using ¹³⁷Cs measurements in floodplain sedimentation studies and presents improved procedures for interpreting ¹³⁷Cs profiles in floodplain sediments and for obtaining estimates of sedimentation rates from single measurements of the total. ¹³⁷Cs inventories of bulk sediment cores. The results obtained from a case study undertaken on the floodplain of the River Stour, Dorset, UK, are presented.  相似文献   

一种新的原油析蜡量测定方法   总被引：1，自引：1，他引：1  

黄启玉  赵晨阳  陈达卫 《油气储运》2005,24(9):34-38

提出了通过原油DSC曲线计算原油析蜡量的方法,其结果与常规方法测量的蜡含量一致,而且能计算不同温度段析出的蜡量.热力学方法计算的析蜡点和通过DSC曲线计算的析蜡点相差0.6℃,不同温度段析出的蜡量相差比较大.与热力学模型相比,该方法简便实用.  相似文献   

植物塘+人工湿地+吸附池系统对灌溉水中痕量Cd的去除效果     

何钟响  董思俊  刘寿涛  李丹阳  彭鸥  刘孝利  铁柏清 《农业环境科学学报》2020,39(6):1293-1302

为了降低灌溉水中Cd向农田输入,减轻农田土壤Cd污染,试验选取梭鱼草、狐尾藻、野茭白为材料,构建"植物塘+人工湿地+吸附池"系统,研究其对湖南典型矿区Cd超标灌溉水净化效果,并分析Cd在系统中的分布规律。结果表明:在2018年11月—2019年9月监测期间,进水全量Cd平均浓度为6.35μg·L~(-1),经系统净化后灌溉水中可溶态Cd、悬浮态Cd及悬浮颗粒物平均去除率分别为86.58%、90.37%和81.54%,构建的人工系统可有效降低灌溉水中Cd含量。进水口悬浮态Cd与悬浮颗粒物呈极显著正相关,悬浮颗粒物与进水流速呈显著正相关。灌溉水Cd输入总量为859.61 g,大气沉降Cd输入总量为95.34 g,处理系统拦截为865.52 g,各个单元拦截量从高到低依次为一级植物塘(544.64 g)三级人工湿地+吸附池(167.62 g)二级植物塘(156.26 g)。3种湿地植物对Cd均有较好的富集效果,富集浓度随水流方向下降。一、二级植物塘底泥最大Cd浓度分别为11.05、4.75 mg·kg~(-1),底泥中Cd弱酸可溶态比值较大,存在向水体解吸释放的风险。所构建的"植物塘+人工湿地+吸附池"净化系统可有效降低湖南典型矿区灌溉水中超标Cd含量,降低农田土壤Cd的灌溉输入通量。  相似文献   

基于转录组测序分析牛不同脂肪组织的脂肪沉积差异研究     

王思元  刘迪  张伟红  王国富  高树新 《西北农业学报》2021,(12):1755-1766

为了更好地了解肉牛(Bos taurus)的脂肪沉积机制，以安格斯牛（Aberdeen Angus）和西门塔尔牛（Simmental cattle）为模型，通过对2种脂肪组织（肾周脂肪和背皮下脂肪）进行RNA测序，确定转录组图谱。分析4个组织中共同的高表达基因，以及2个组织之间的差异表达基因。结果显示，每个样品获得约10.99 Gb数据，并注释总共23 472个基因。在50个高度表达的共同基因中，发现脂肪酸结合蛋白4（Fatty Acid Binding Protein4, FABP4），脂肪形成调节因子(Adipogenesis Regulatory Factor,ADIRF)和硬脂酰辅酶A去饱和酶(Stearoyl-CoA Desaturase,SCD)是与脂肪沉积相关的基因，表明这3个基因可能在脂肪沉积中发挥作用。在安格斯牛和西门塔尔牛的肾周脂肪与皮下脂肪组织之间分别鉴定出1 678个和1 955个差异表达基因。GO分析表明，一些DEG与代谢有关。KEGG途径分析显示，PPAR信号途径、甘油酯代谢和ECM-受体相互作用途径富集丰富。在背皮下脂肪中，PPAR信号途径和甘油脂代谢中的3个基因：视黄酸X受体α(retinoid X receptor alpha,RXRA)、C1q肿瘤坏死因子相关蛋白7(C1q and TNF related 7, C1QTNF7)和单酰甘油-O-酰基转移酶2(Monoacylglycerol O-acyltransferase 2, MOGAT2)上调；6个基因：肉碱脂酰转移酶1B(Carnitine Palmitoyltransferase 1B, CPT1B) 、解偶联蛋白1(Uncoupling Protein 1, UCP1)、 脂肪酸结合蛋白3(Fatty Acid Binding Protein 3, FABP3)、 脂肪酸转位酶(Fatty Acid Translocation enzyme, CD36) 、脂蛋白1( LPIN1) 和甘油-3-磷酸酰基转移酶3(Glycerol-3-phosphate Acyltransferase 3, GPAT3)表达量下调。在ECM-受体相互作用中，发现Ⅰ型胶原Α1(Collagen Type I alpha 1 Chain, COL1A1)、III型胶原Α1(Collagen Type III alpha 1 Chain, COL3A1) 、Ⅰ型胶原Α2(Collagen Type I alpha 2 Chain, COL1A2)和II型胶原Α1(Collagen Type II alpha 1 Chain, COL2A1)在牛的背皮下脂肪中上调，而层粘连蛋白γ3(Laminin Subunit gamma 3 , LAMC3) 和粘连蛋白γ2(Laminin Subunit gamma 2, LAMC2)的表达量下调。为验证转录组的准确性，对差异基因 COL1A1、 COL3A1、RXRA、 LPIN1和 GPAT3进行qPCR验证，结果显示qPCR结果与转录组测序数据基本一致。本研究揭示了肉牛不同脂肪组织中复杂的转录组图谱，发掘了参与脂肪沉积的候选基因。  相似文献   

果树树冠静电喷雾的空间电荷效应分析   总被引：3，自引：0，他引：3  

舒朝然  詹敏  盛茂领  陈国发  林强 《沈阳农业大学学报》2007,38(1):59-64

以风送静电喷雾机为例,描述了杀虫剂药液被气流剪切式喷嘴雾化时雾滴的诱导充电过程,建立了一个树冠静电喷雾过程的电子—机械简化模型,用于分析雾滴沉积过程中作用于荷电雾滴的静电力(镜像力、空间电荷力和空间电荷引力)和机械力(重力和拉力)。静电力的相对大小是通过与机械力的力比值作比较的,50μm和100μm两种充电雾滴的典型的力比值说明空间电荷引力在雾滴沉积过程中起着重要的作用。  相似文献