Effects of hair coat characteristics on radiant surface temperature in horses

Horse owners may lack knowledge about natural thermoregulation mechanisms in horses. Horses are managed intensively; usually stabled at night and turned out during the day. Some are clipped and many wear a blanket, practices which reduce the horse's ability to regulate heat dissipation. The aim of this study was to investigate the relationship between hair coat characteristics, body condition and infrared surface temperatures from different body parts of horses. Under standard conditions, the body surface temperature of 21 adult horses were investigated using infrared thermography. From several readings on the same body part, a mean temperature was calculated for each body part per horse. Detailed information on horse breed, age, management and body condition was collected. Hair coat samples were also taken for analyses. A mixed statistical model was applied. Warmblood horse types (WB) had lower hair coat sample weights and shorter hair length than coldblood horse types (CB). The highest radiant surface temperatures were found at the chest 22.5 ± 0.9 °C and shoulders 20.4 ± 1.1 °C and WB horses had significantly higher surface temperatures than CB horses on the rump (P < 0.05). Horses with a higher hair coat sample weight had a lower surface temperature (P < 0.001) and hind hooves with iron shoes had a significant lower surface temperature than unshod hind hooves (P = 0.03). In conclusion, individual assessment of radiant surface temperature using infrared thermography might be a promising tool to gather data on heat loss from the horses' body. Such data may be important for management advice, as the results showed individual differences in hair coat characteristics and body condition in horses of similar breeds.     

Daytime relapse of the mean radiant temperature based on the six-directional method under unobstructed solar radiation

This study contributes to the knowledge about the capabilities of the popular “six-directional method” describing the radiation fields outdoors. In Taiwan, measurements were carried out with three orthogonally placed net radiometers to determine the mean radiant temperature (T _mrt). The short- and long-wave radiation flux densities from the six perpendicular directions were recorded in the daylight hours of 12 days. During unobstructed direct irradiation, a specific daytime relapse was found in the temporal course of the T _mrt values referring to the reference shapes of a standing man and also of a sphere. This relapse can be related to the short-wave fluxes reaching the body from the lateral directions. Through deeper analysis, an instrumental shortcoming of the six-directional technique was discovered. The pyranometer pairs of the same net radiometer have a 10–15-min long “blind spot” when the sun beams are nearly perpendicular to them. The blind-spot period is supposed to be shorter with steeper solar azimuth curve on the daylight period. This means that the locations with lower geographical latitude, and the summertime measurements, are affected less by this instrumental problem. A methodological shortcoming of the six-directional technique was also demonstrated. Namely, the sum of the short-wave flux densities from the lateral directions is sensitive to the orientation of the radiometers, and therefore by deviating from the original directions, the T _mrt decrease on clear sunny days will occur in different times and will be different in extent.     

Comparison of different methods of estimating the mean radiant temperature in outdoor thermal comfort studies

Correlations between outdoor thermal indices and the calculated or measured mean radiant temperature T_mrt are in general of high importance because of the combined effect on human energy balance in outdoor spaces. The most accurate way to determine T_mrt is by means of integral radiation measurements, i.e. measuring the short- and long-wave radiation from six directions using pyranometers and pyrgeometers, an expensive and not always an easily available procedure. Some studies use globe thermometers combined with air temperature and wind speed sensors. An alternative way to determine T_mrt is based on output from the RayMan model from measured data of incoming global radiation and morphological features of the monitoring site in particular sky view factor (SVF) data. The purpose of this paper is to compare different methods to assess the mean radiant temperature T_mrt in terms of differences to a reference condition (T_mrt calculated from field measurements) and to resulting outdoor comfort levels expressed as PET and UTCI values. The T_mrt obtained from field measurements is a combination of air temperature, wind speed and globe temperature data according to the forced ventilation formula of ISO 7726 for data collected in Glasgow, UK. Four different methods were used in the RayMan model for T_mrt calculations: input data consisting exclusively of data measured at urban sites; urban data excluding solar radiation, estimated SVF data and solar radiation data measured at a rural site; urban data excluding solar radiation with SVF data for each site; urban data excluding solar radiation and including solar radiation at the rural site taking no account of SVF information. Results show that all methods overestimate T_mrt when compared to ISO calculations. Correlations were found to be significant for the first method and lower for the other three. Results in terms of comfort (PET, UTCI) suggest that reasonable estimates could be made based on global radiation data measured at the urban site or as a surrogate of missing SR data or globe temperature data recorded at the urban area on global radiation data measured at a rural location.     

城市不同地表覆盖类型对土壤呼吸的影响

采用Licor-6400-09的土壤呼吸测量系统对北京市区3种不同覆盖类型地表(全硬地表、半透砖地表、草坪覆盖地表)的土壤呼吸速率及其影响因子进行了测定和分析。结果表明:(1)不同地表覆盖类型的土壤呼吸速率年均值分别为7.928 μmol·m^-2·s^-1(全硬地表),5.592 μmol·m^-2·s^-1(部分硬化地表)、2.625 μmol·m^-2·s^-1(草坪覆盖地表);土壤呼吸日均值最高均出现在夏季(14.785,10.296,5.143 μmol·m^-2·s^-1),最低为冬季(0.490,0.319,0.239 μmol·m^-2·s^-1);(2)3种地表类型的土壤呼吸速率有显著差异(P<0.05),大小排序为:草坪覆盖地表<部分硬化地表<全硬地表;(3)3种地表类型土壤呼吸速率均与土壤温度呈显著的指数相关,Q₁₀值排序为:草坪覆盖地表<部分硬化地表<全硬地表;(4)土壤含水率和土壤电导率与土壤呼吸均有一定的相关性,但关系较为复杂,有待于进一步研究。     

城市地表硬化对植物生理生态的影响研究进展

城市地表硬化是城市发展和扩张的主要表征之一,也是影响城市生态环境及植物生理生态的重要原因。在分析城市地表硬化引起植物生态因子变化的基础上,重点综述了地表硬化对植物气体交换、水分平衡、养分循环等生理生态过程的影响,归纳了不同地表硬化性质、气候季节变化、植物类型以及群落结构等因素对地表硬化景观植物生理生态影响的差异。探讨了目前该领域研究中存在的问题,并提出今后研究建议,以期为优化城市生态用地结构,提高城市植物的生态系统服务,改善城市和人居环境提供一定的科学依据。     

The effects of tree characteristics on rainfall interception in urban areas

Trees in urban areas have significant effects on the urban ecosystem. They can be used to improve the water cycle in urban areas by increasing evaporation and reducing runoff through rainfall interception. Street trees placed in planters on impervious areas reduce runoff by intercepting rainfall and by temporarily storing raindrops on leaves. Therefore, understanding tree canopy geometry and the effect of rainfall interception is important in urban hydrology. In this study, we assessed the effect of tree canopy morphology on rainfall interception using four major street tree species, Sophora japonica L., Ginkgo biloba L., Zelkova serrata (Thunb.) Makino, and Aesculus turbinata Blume, in Seoul, South Korea. We measured throughfall for each tree and also derived three-dimensional data of tree canopy morphology with a terrestrial laser scanner. Tree height, canopy crown width, leaf area index (LAI), leaf area density, mean leaf area, and mean leaf angle were used to determine canopy morphology. The interception rate was mostly affected by the LAI; a higher LAI tended to result in a higher interception rate. Leaf area affected the rainfall interception rate when trees had similar LAIs. These findings on individual tree canopy rainfall interception can help us to understand the importance of rainfall interception in hydrology and for ecological restoration when planning urban green spaces.

     

Some improvements in calculating the plant stand surface albedo and its influence on ground surface temperature

It is shown that better results are obtained in calculating the surface albedo of a plant stand for near-infrared solar radiation using the modified two-stream approximation in favor of the Schwarzschild one. These evaluations of the plant stand surface albedo were obtained by assuming the values for scattering parameters of upward ₀ and diffusive solar radiation in the plant stand, by applying the delta-Eddington approximation. However, more accurate evaluations of ₀ and can be obtained by using Rayleigh's phase scattering functions for radiative scattering in a plant stand. Furthermore, much attention is devoted to testing the influence of the plant stand albedo for the visible part of solar radiation (for which the Schwarzchild approximation is valid) on ground surface temperature. The ground surface temperature was calculated by the force-restore method; the greatest ground surface temperature corrections were obtained in cases where the surface beneath the plant stand is covered with snow. The influence on ground surface temperature of high absorption and scattering in dense plant stands with horizontal foliage was also tested. Again significant corrections of ground surface temperature were obtained, taking into consideration the given characteristics of a plant stand compared to a standard albedo value.List of symbols A albedo of direct radiation in plant canopy - A _D albedo of diffuse radiation in plant canopy - A _p albedo of the ground surface - A _Q total albedo in plant canopy - a proportion of gaps in plant canopy characteristic of surface evaporation - _w constant - parameter of upward scattering diffuse radiation - ₀ parameter of upward scattering direct radiation - C _g soil volumetric heat capacity - C _p air specific heat - C _DH aerodynamic transfer coefficient for heat - C _DE aerodynamic transfer coefficient for moisture - d depth of soil - sun's declination - azimuth of incident radiation - azimuth of diffuse radiation - characteristic of the radiative sources - G foliage orientation function - g parameter in delta-Eddington approximation - g _z parameter for near-infrared radiation - _L scattering phase function radiation - _D diffuse solar radiation flux - _G soil heat flux - _H air sensible heat flux - _L air latent heat flux - _O solar constant - _R net longwave radiation flux - _S direct solar radiation flux - h _o height of the sun - i intensity of diffuse radiation - k von Karman constant - L leaf area index - L _v coefficient for latent heat of evaporation - _g soil heat conductivity - n/N relative cloudiness - solid angle - frequency of temperature wave - Q _a specific humidity of air - Q _w specific humidity of saturated air - R _L coefficient of plant reflectivity - r direction of diffuse radiation - direction of incident radiation - r _o direction of solar radiation - r _s resistance of the leaf stomata - p _o air density - S intensity of direct solar radiation - Stefan-Boltzman constant - T _a air temperature - T _G ground surface temperature - T _c cloud temperature - T ₁ feaf temperature - T _* air temperature scale - t time - t time step - zenith angle of diffuse radiation - zenith angle of incident radiation - ₀ zenith angle of solar radiation - U _* friction velocity scale - V near-surface wind velocity - W _g soil water content - W _L scattering coefficient in plant canopy - W _sat saturated soil water content - z vertical direction     

有机地表覆盖物在城市林业建设中的应用价值

综述了国外有机地表覆盖物兴起与发展的过程,重点分析了有机地表覆盖物的重要应用价值(如改善土壤理化性状、促进树木生长、美化城市景观、抑制土壤扬尘及其环保和经济价值,同时对有机地表覆盖物使用中的问题进行了分析,指出了我国城市林业建设中有机地表覆盖物生产与应用的现实紧迫性和广阔发展空间.     

基于光纤测温技术的城市地表温度精细化分析

城市景观空间构型与热岛效应关联性较强,研究高时空分辨率的城市不同下垫面地表温度变化,可以更加精细地掌握城市热环境的时空特征。光纤温度传感系统具有实时在线、测温精度高和不受电磁干扰等优点,具备实时、在线、连续开展城市地表温度在线监测的能力。在北京市通州某园区内,选择有太阳辐射的4个时段,对多种类型下垫面的地表温度进行了时间间隔为1 min、空间间隔为1 m的连续4 h、总长度为100 m的实时在线监测。通过对监测时间段内不同类型下垫面地表温度的变化分析,发现这种分布式光纤测温系统能够有效辨识小尺度下地表温度的时间变化性和空间变化性,能有效区分透水和不透水地面,并监测和评估沥青马路地表温度的升温速率以及遮荫效果对地表温度的降温作用。同时,这种监测模式获取的数据能够对地表温度空间序列开展自相关分析,进一步验证了地表温度空间序列在较小尺度上仍然具有自相关性,且距离越近,相关性越大。研究同时表明,光纤测温技术能直接地获取城市热环境的现场真实数据,可以有效应用于小尺度城市热环境的观测与研究。     

1961-2010年桂林气温和地温的变化特征

关于气温变化特征已有大量研究,但是关于地温变化及其与气温的关系研究还较少.以亚热带湿润地区的广西桂林气象站为研究对象,分析了1961-2010年桂林气温和0-80 cm各层地温的年代和季节变化趋势、地气温差变化、气候突变和异常年份以及气温和地温关系.结果表明:气温与各层地温有很好的相关性.各年、季平均气温和各层平均地温大部分呈显著的升高趋势,但气温和地温的增温速率不一致,即升温存在非对称性;年均气温低于各层地温1.3-2.1℃,气温的增温速率和增温幅度分别为0.184℃/10 a和0.8℃,高于除0 cm外其它各层地温的变化;气温、5-40 cm地温在冬季的增温最多,0 em和80cm地温分别在秋季和夏季的增温最多;春、夏季,随着土壤深度的增加,地温呈减小趋势,春季气温小于0-15 em而大于20-80 cm地温,夏季气温小于0-40 cm而大于80 em地温;秋、冬季,随着土壤深度的增加,地温呈增加趋势,秋、冬季气温小于各层地温;气候变暖背景下,年平均、四季气温比除0 em外其它各层地温的响应更快.近50年来,各层地温和气温的温差减小了0.1-0.4℃(0 em地温和气温温差除外),这主要是因为气温的增加幅度要大于地温,且随着土壤深度的增加,地气温差的减小幅度加大.桂林年均地温和四季气温、地温大多无气候突变现象,仅有年均气温和夏季80 em地温分别在1997和1977年出现气候突变.春季气温和5-80 cm各层地温的异常偏低年较一致;秋季气温和40、80 cm地温的异常偏低年相同;夏、冬季气温和地温的异常年份对应性较差;而年均气温和各层地温的异常偏高年较一致.     

保藏温度对厌氧氨氧化颗粒污泥特性的影响

为考察保藏温度对厌氧氨氧化污泥颗粒特性的影响,同时优化保藏厌氧氨氧化颗粒污泥温度参数,本试验首先通过HRT调控进水基质负荷培养厌氧氨氧化颗粒污泥,并采用KHCO3和Na HCO3交替提供无机碳源。然后分别在–40℃、4℃、(27±4)℃室温和35℃条件下避光保藏。结果表明,Na HCO3可代替KHCO3作为厌氧氨氧化菌生长的无机碳源。相比于其他保藏温度,4℃保藏能够较好地维持生物量和生物活性,同时能较好地维持颗粒污泥的沉降性能、颗粒污泥和细胞结构完整性。在保藏过程中,一阶衰减指数模型可拟合厌氧氨氧化颗粒污泥生物量及活性的衰减过程,衰减指数与胞溶程度正相关,而且生物量的衰减比活性的衰减更快。同时,颗粒污泥胞外聚合物中蛋白质与多糖的比值(PN/PS)和血红素不能有效指示保藏过程中颗粒污泥沉降性能和活性的变化,而生物活性与胞溶程度呈负相关。     

Influence of surface characteristics on the stability of Cryptosporidium parvum oocysts

Microelectrophoresis is a common technique for probing the surface chemistry of the Cryptosporidium parvum oocyst. Results of previous studies of the electrophoretic mobility of C. parvum oocysts in which microelectrophoresis was used are incongruent. In this work we demonstrated that capillary electrophoresis may also be used to probe the surface characteristics of C. parvum oocysts, and we related the surface chemistry of C. parvum oocysts to their stability in water. Capillary electrophoresis results indicated that oocysts which were washed in a phosphate buffer solution had neutrally charged surfaces. Inactivation of oocysts with formalin did not influence their electrophoretic mobility, while oocyst populations that were washed in distilled water consisted of cells with both neutral and negative surface charges. These results indicate that washing oocysts in low-ionic-strength distilled water can impart a negative charge to a fraction of the oocysts in the sample. Rapid coagulation experiments indicated that oocysts did not aggregate in a 0.5 M NaCl solution; oocyst stability in the salt solution may have been the result of Lewis acid-base forces, steric stabilization, or some other factor. The presence of sucrose and Percoll could not be readily identified on the surface of C. parvum oocysts by attenuated total reflectance-Fourier transform infrared spectroscopy, suggesting that these purification reagents may not be responsible for the stability of the uncharged oocysts. These findings imply that precipitate enmeshment may be the optimal mechanism of coagulation for removal of oocysts in water treatment systems. The results of this work may help elucidate the causes of variation in oocyst surface characteristics, may ultimately lead to improved removal efficiencies in full-scale water treatment systems, and may improve fate and transport predictions for oocysts in natural systems.     

北京城区人工构筑物对比邻绿地土壤温度和含水量的影响

选取城市中分布最广的两类人工构筑物——沥青和混凝土为研究对象,采用构筑物-绿地梯度样带法,观测这2类典型城市构筑物对比邻绿地土壤温度和含水量的影响,分析不同构筑物的质地、面积、形态等构筑物特征对土壤水、热分布的影响强度及范围。研究显示:1)夏、秋季在构筑物-绿地梯度样带上,绿地土壤温度在比邻构筑物端(a点)处最高,并且白天中午、傍晚时段a点温度显著高于梯度上其他观测点和对照点;2)绿地土壤含水量在比邻构筑物端(a点)处最低,而且土壤含水量变化在梯度样带上从a点至远离构筑物端的对照点变化具有不确定性,可能受城区土壤蒸散、人工灌溉、土壤地下生物量等不确定因素的影响。3)梯度样带上土壤温度(T)和水分(W)与离a点距离(D)均呈现幂函数定量关系,即沥青样地T=0.7708(579.4957-0.9984D)0.5843,W=0.1970(0.0505+0.1347D)0.2262;混凝土样地T=0.7615(583.7027-1.0986D)0.5746,W=0.2224(-0.6019+0.3473D)0.0595。4)在构筑物-绿地梯度样带上,土壤温度和含水量受构筑物影响幅度大概在0—100 cm之间,而且随构筑物质地及分布格局、城市气象以及绿地构成、结构、人工管理方式等因素的影响而变化。     

城市地表径流污染来源的分类与特征

城市地表径流中污染物的分布和浓度等污染特征取决于其污染来源。本文依据3种分类方法分析了城市地表径流污染物的来源及其特征,重点讨论了城市地表径流中主要的污染物悬浮颗粒物、持久性有机污染物、农药、重金属、营养元素、有机质和其他有代表性的工业源化合物的来源、污染特征和生态风险等,介绍了城市地表径流对受纳水体的影响及其评价方法,并探讨了今后的研究重点。     

城市地表温度与关键景观要素的关系

利用Landsat ETM+遥感影像,提取上海市外环线范围内的地表温度、不透水面率、归一化差值植被指数、改进的归一化差异水体指数,定量研究地表温度与城市关键景观类型之间的关系.结果表明:地表温度与不透水面率呈显著的线性正相关( R2=0.837);地表温度与归一化差值植被指数和改进的归一化差异水体指数呈非线性关系,但地表温度与正的归一化差值植被指数和正的改进的归一化差值水体指数呈显著线性关系.鉴于归一化差值植被指数和改进的归一化差异水体指数大于0时才能真正代表植被和水体,因此,建议今后研究地表温度时使用正的归一化差值植被指数和改进的归一化差异水体指数;地表温度与不透水面率、归一化差值植被指数和改进的归一化差值水体指数的多元线性回归分析表明,不透水面起着增温作用,植被、水体起降温作用,植被较水体的降温作用大.