广州地区光化辐射通量与辐照度的特征

应用NCAR TUV辐射模式与地表实际观测分析了理论上广州地区地表可获得的最强光化辐射通量、辐照度及其波谱变化特征与月、日变化特征,计算与观测的差异用于评估气溶胶对紫外辐射通量的作用.结果表明,光化辐射通量与辐照度均具有正弦曲线的日变化特征,但光化辐射通量的正弦波形较辐照度的更为宽广,其辐射强度随太阳天顶角的增加下降幅度也更为缓慢;光化辐射中的总能量可见光谱区约占86%,紫外谱区仅占约14%;理论计算与实际观测表明,不同监测波段范围的紫外辐射表,虽然其标识均为监测UVA或UVB的辐射,但差异明显;广州地区的气溶胶污染显著影响紫外辐射通量.由于紫外辐射通量是影响对流层臭氧生产力的关键因子,有必要更加深入地认识广州地区气溶胶与紫外辐射通量的相互作用.     

Identification of important factors for water vapor flux and CO2 exchange in a cropland

Water vapor flux and carbon dioxide (CO₂) exchange in croplands are crucial to water and carbon cycle research as well as to global warming evaluation. In this study, a standard three-layer feed-forward back propagation neural network technique associated with the Bayesian technique of automatic relevance determination (ARD) was employed to investigate water vapor and CO₂ exchange between the canopy of summer maize and atmosphere in responses to variations of environmental and physiological factors. These factors, namely the photosynthetically active radiation (PAR), air temperature (T), vapor pressure deficient (VPD), leaf-area index (LAI), soil water content in root zone (W), and friction velocity (U*), were used as inputs in neural network analysis. Results showed that PAR, VPD, T and LAI were the primary factors regulating both water vapor and CO₂ fluxes with VPD and W more critical to water vapor flux and PAR and T more crucial to CO₂ exchange. Furthermore, two time variables “day of the year (DOY)” and “time of the day (TOD)” could also improve the simulation results of neural network analysis. The important factors identified by the neural network technique used in this study were in the order of PAR > T > VPD > LAI > U* > TOD for water vapor flux and in the order of VPD > W > LAI > T > PAR > DOY for CO₂ exchange. This study suggests that neural network technique associated with ARD could be a useful tool for identifying important factors regulating water vapor and CO₂ fluxes in terrestrial ecosystem.     

重庆地区大气干降尘化学组分及其在中和降雨酸度中的作用

用直径50cm 的聚乙烯漏斗,在冬夏两季分别截获了白天和夜间的干降尘。结果表明,干降尘中主要阳离子是钙,虽然它吸附二氧化硫,但不酸。计算表明城区干降尘能中和降水中11.8％的酸,四面山中和6.2％。     

固体通量法在沸石强化A/O脱氮工艺二沉池中的应用

分析了固体通量的理论基础及其在二沉池设计与运行控制上的应用。利用固体通量理论对某污水处理厂中试现场装置进行分析,结果表明：固体通量法可用于判断二沉池的运行控制是否正确合理;当负荷发生变化时,可以通过固体通量分析来改变操作条件,以保证二沉池正常运行。     

Pools and Fluxes of Cations,Anions and Doc in Two Forest Soils Treated With Lime and Ash

The effect of liming and ash treatment on pools, fluxes and concentrations of major solutes was investigated at two forestedsites (Norway spruce) in S. Sweden. One site was treated 15 yrprior to sampling (Hasslöv-Hs; dolomite: 3.45 and 8.75 t ha^-1) and the other 4 yr before (Horröd-Hd; dolomite: 3.25 t ha^-1; wood ash: 4.28 t ha^-1). Effects of limingwere most pronounced in the O horizon solutions where higher pH,elevated Ca (120–700 M) and Mg (50–600 M) were observed as compared to control plots. The impact on the mineralsoil was more moderate. Soil solution concentrations were combined with modelled hydrological flow to calculate mass flows,which largely followed the trends of the solution composition. Liming also resulted in large increases of both exchangeable Caand Mg as well as effective cation exchange capacity (CEC_E;2–5 times the controls). The base saturation (BS%) was raised to 60–100% in the O horizon while in the mineral soil elevated values were only seen at the Hs site (20–60%; down to 10–15 cm depth for 8.75 t ha^-1). Ash treatment did notaffect either the soil solution nor the exchangeable pool to thesame extent as lime. In general, the impact at the Hd site was less pronounced especially in the mineral soil, which might be due to shorter treatment time (4 vs. 15 yr) and also differentthickness of the O horizon. Budget calculations for Ca and Mg originating from the lime showed that a major part of the Ca (40–100%) was retained in the top 30 cm of the soil, of which30–95% was present in the O horizon. The mobility of Mg wasgreater and it was estimated that a significant part had been leached from the profile (30 and 50 cm depth) after 15 yr. Increased mass flows of NO₃ ^- due to nitrification resulting from liming at the Hs site were calculated in the range120–350 mmol m^-2 yr^-1 (or 1.2–3.5 kmol ha^-1 yr^-1). There was significant leaching of Al (25–60 mmol m^-2 yr^-1), of which about 70% was inorganic, in thelower B horizon at both sites with no influence of liming.     

BLEVE火球热辐射及其影响评价模型介绍

高压液化易燃、易爆化学品储罐易发生BLEVE,引起热辐射,会造成周围人员伤亡和设备损坏.介绍了BLEVE火球热辐射及其影响模型,通过该模型可以计算BLEVE火球的尺寸、持续时间、升空高度、热辐射通量及预测暴露在BLEVE火球热辐射通量下人的致死概率.     

Why Critical Loads of Acidity and N for Soils Should be Based on Pollutant Effective Concentrations Rather Than Deposition Fluxes

Numerous assumptions have been made over the past 17 years when calculating critical loads for soils, both for acidity (based upon base cation steady state mass balances (SMB)) and for N (eutrophication, based upon N mass balances), often without all the assumptions being explicitly stated. The tacit assumptions that the author believes to be implicit in the SMB approach are critically reviewed, with particular reference to upland regions where slope processes are highly significant. It is concluded that many of them cannot be justified, especially those that involve ignoring many key processes known to be important to biogeochemical cycling and soil evolution in upland catchments. The evidence presented suggests that critical loads of acidity and of N for soils should be based upon effective pollutant and, for acidity, also effective base cation deposition concentrations, rather than upon pollutant deposition fluxes. This is because of the dominant role of cation exchange equilibria, rather than weathering rate, in regulation of the pH and base status of the more acidification-sensitive soils, and because of the importance of transport down slope of base cations, alkalinity and N species.     

上升热流条件下木材表面温度的实验研究

本文利用热电偶对上升热流条件下不同种类木材的表面温度进行了实验测量。实验中选取的不同上升热流过程是为了更好的模拟实际室内火灾发展过程。实验结果表明,热流上升速率及木材密度都会影响木材的表面温升过程。点燃时刻表面温度随热流变化率的增加而降低,而木材密度对其影响不大。     

三江平原典型沼泽湿地养分累积与沉积特征

研究了三江平原两类典型沼泽湿地(毛果苔草沼泽和芦苇沼泽)沉积物剖面有机碳、全氮、全磷和全硫的垂直分布规律,初步分析了三江平原湿地的沉积速率与沉积通量.结果表明,土壤有机碳、全氮、全磷和全硫在垂直方向上具有明显的分层和富聚现象,自上而下,有机碳的含量逐渐降低;全氮含量呈先增加后减少的分布趋势;毛果苔草沼泽全磷含量呈先减少后增加的"V"型分布,芦苇沼泽全磷含量逐渐降低;全硫的分布和有机碳的分布规律一致.相关性分析表明,全氮、全磷和全硫与有机碳之间呈极显著的正相关关系(P<0.01);有机碳与容重之间呈极显著的负相关关系(P<0.01).植被类型是影响沼泽湿地土壤有机碳、全氮、全磷和全硫的空间分布的主要因素之一.应用137Cs、210Pb测定沉积年代,并结合恒定放射性通量(CRS)模式推算年龄的结果表明,三江平原湿地平均沉积速率为0.33 cm·a-1,沉积通量为0.03～0.48 g·(cm2·a)-1,平均为0.29 g·(cm2·a)-1.     

冠层辐射温度对冬小麦生态系统碳通量的影响

用箱式法在太原盆地对冬小麦的碳通量进行了两年的测定,对比分析了气温(T_a)、土壤温度(T_s)和冠层辐射温度(T_c)的日、季节变化与冬小麦碳通量日、季节变化的关系.结果表明,在日、季节尺度上T_c与T_a具有较好的一致性,相关系数在0.90以上;日尺度上,净生态系统碳交换量(NEE)、总初级生产力(GPP)、生态系统呼吸(Reco)与T_s的相关系数在绝大部分测定日都小于与T_a和T_c的相关系数,但它们与T_a和T_c的相关系数差异不大;季节尺度上,冬小麦的GPP、NEE和Reco与3个温度(T_a、T_s和T_c)都呈显著的二次抛物线关系.生态系统光合作用的最适温度T_c略低于T_a的,差异约1℃左右.Reco与T_a的关系均好于与T_s的关系,与T_c、T_a关系的决定系数差异不大(0.95~0.96).研究结果可以为基于遥感方式观测的冠层辐射温度在估算碳通量中的应用提供依据.