林火预防与扑救投资的成本效益分析

针对某一林区,确定其林木管理目标,以及为达到此目标对林火监测与扑救系统的要求,从而确定森林防火的资金投入。分析了加大森林防火投入前后森林火灾损失与扑求费用的变化。     

水稻秸秆沟埋还田对麦田土壤环境的影响

通过大田试验,采用秸秆沟埋还田方式,设置沟埋深度分别为20、30、40、50 cm及对照5个处理,将上季作物秸秆进行全量还田(秸秆沟埋量为2 kg.m-1),研究水稻秸秆沟埋还田对麦田土壤含水量、温度、容重和孔隙度等的影响。结果表明,降水结束后12 d内,沟埋深度20和30 cm处理土壤含水量(与埋草沟边水平距离10 cm处)显著下降(P<0.05);而沟埋深度40和50 cm处理土壤含水量(与埋草沟边水平距离10 cm处)与对照差异未达显著水平。埋草沟秸秆下层土壤温度变化较小,秸秆对下层土壤具有保温作用;除沟埋深度20 cm处理外,其他不同沟埋深度处理均能明显降低秸秆上层土壤容重,增加土壤总孔隙度,使耕层土壤疏松。     

2017年华北平原采暖季和非采暖季道路PM10污染特征和健康风险评估——以济南市为例

由于污染程度较重和其所携带的大量毒性成分,大气颗粒物对人体健康具有重要影响。根据济南市51个道路颗粒物监测点PM₁₀数据,讨论了采暖季和非采暖季道路PM₁₀的浓度水平和健康风险。结果表明：（1）道路PM₁₀的平均浓度是城市背景站点的1.5倍,道路PM₁₀浓度水平主要受车流量和道路施工活动的影响。由于燃煤量的增加,采暖季的PM₁₀平均浓度是非采暖季的1.3倍。（2）从空间变化来看,这些道路站点可以分为三类,其中第二类由于受建筑活动和交通源影响,PM₁₀浓度最高,第一类由于具有绿化带和好的周围环境,PM₁₀浓度最低。（3）从时间变化来看,在非采暖季,周六浓度最高,周二浓度最低;在采暖季,周四浓度最高,周六和周二浓度最低。PM₁₀较高浓度出现在早晚,与交通源密切相关。（4）除了非采暖季PM₁₀对成年人没有健康风险,其他情况下,PM₁₀均有健康风险。     

全绿吊兰茎叶系统净化室内甲醛及其生理指标变化

为了对全绿吊兰盆栽茎叶系统净化室内空气甲醛污染的效率及其叶片各生理指标的变化特征进行全面研究,采用动态熏蒸系统在甲醛环境下对全绿吊兰进行长达7 d的熏蒸处理,分析盆栽茎叶系统在不同时间段内对空气中甲醛的去除率及熏蒸后叶片的生理变化特性.结果表明,全绿吊兰盆栽茎叶系统在φ（甲醛）为1×10-6、5×10-6及8×10-6时对空气中甲醛的平均去除率分别为54.4%、48.2%和30.7%,并且白天的去除率（71.1%±0.2%）明显高于夜间（36.2%±0.2%）,下午的去除率（60.0%±0.0%）高于上午（50.7%±0.1%）,熏蒸后期的去除率（57.0%±0.2%）高于前期（51.9%±0.3%）.对熏蒸后全绿吊兰盆栽叶片的生理指标测定结果表明,与对照组相比,除了叶片中w（叶绿素）和CAT活性下降外,其余生理指标均表现为上升,其中,电导率和H₂O₂含量的变化最大,φ（甲醛）为8×10-6时分别提高了165.8%和522.2%,而抗氧化酶总活性的增强有效地清除了积累的氧化物,维持了全绿吊兰盆栽的正常生长.另外,经过8×10-6的甲醛熏蒸后,与对照组相比,叶片表面气孔形态变得更加细小狭长甚至完全闭合,但是全绿吊兰盆栽的茎叶外观并无明显受损症状,而且叶片中MDA含量与T-AOC活性在熏蒸后15 d时基本能恢复至正常水平.研究显示,全绿吊兰盆栽对甲醛具有较高的去除能力且有较强的抗耐性及自愈能力,其叶片中各项生理指标的变化则反映了全绿吊兰盆栽与甲醛之间的相互反应机制.      

季节性温度升高对落干期消落带土壤氮矿化影响

为揭示季节性温度升高对消落带落干期土壤氮矿化的影响,分别采集三峡支流澎溪河消落带上游和下游两个水文断面,155 m(低)、165 m(中)和175 m(高)这3个水位高程表层土壤,结合落干期气温变化特点,在25℃和35℃两个温度下进行恒温培养.结果表明,消落带土壤总氮和硝态氮在上游断面和高水位高程含量更高,而下游和低水位高程含量更低,铵态氮分布与其相反.硝态氮是无机氮的主要存在形式,占无机氮的57.4%~84.7%.相同培养温度下,氨化、硝化、净氮矿化速率均表现为随水位高程增加,随流域断面由下至上而显著增加(P0.05);总体上,在水位高程和流域断面上均表现为:温度升高使硝化速率和净氮矿化速率显著增加(P0.05),而对土壤氨化速率无显著影响(P0.05).     

Dynamics of bacterial community of Suillus granulatus mushroom shiro in Pine (Pinus tabuliformis) forests北大核心CSCD

To evaluate bacterial community variation in the mushroom shiro of Suillus granulatus during fruiting, we collected soil samples from the mushroom shiro in the pine (Pinus tabuliformis) forest of mountainous area in Beijing from May to November and evaluated the bacterial community using polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE). Total soil DNA was extracted using a commercial soil DNA isolation kit. PCR amplification and DGGE were performed using bacterial universal primers 338F and 518R. The specific bands were excised from the gel and sequenced. The results revealed that soil bacterial community maintained considerably high level and changed seasonally with the mushroom fruiting. In total, 53 bands of DGGE profiles were sequenced and divided into 5 phyla (Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria and 22 genera (Acidobacterium, Aminobacter, et al). Species from Proteobacteria and Acidobacteria were the dominant bacterial groups sharing considerably high relative abundance, while class a-Proteobacteria was the most abundant group. The variation of the relative abundance of γ-Proteobacteria species was consistent with the mushroom fruiting season. The relative abundance of Acidobacteria species obviously increased before mushroom flush (in July). The fruiting of S. granulatus and the relative abundance of γ-Proteobacteria were correlated with each other. The present study provided a basis for conservation and domestication of mushroom S. granulatus.     

西南技术工程研究所, 重庆 400039

目的建立敦煌地区温度、相对湿度和日温差的年极值拟合模型。方法根据当地气象站台温度和相对湿度日记时值数据,连续统计若干年的三要素年极值,采用极大似然法建立各要素年极值的Gumbel模型,同时讨论值域有界类气象因素极值再现期的定义域。结果给出了敦煌地区温度、相对湿度和日温差年极值的Gumbel模型参数。结论敦煌地区各气象因素Gumbel模型位置参数和尺度参数,温度极大值分别为35.193,1.072℃,温度极小值分别为-20.085,1.945℃,相对湿度极大值为95.254%,2.471%,相对湿度极小值为5.837%,1.505%,日温差极大值为20.676,0.777℃,日温差极小值为1.398,0.593℃;相对湿度极大值、相对湿度极小值和日温差极小值的再现期定义域分别为6.3,47和10年。     

线性拟合法评定水中砷的测量不确定度研究

测量不确定度是评定测量值分散程度的一项指标,对解释测量结果非常重要,对于一个分析方法若未进行不确定度评估,则无法确定测量结果间观测到的差值是否包含试验变异以外的信息,没有不确定度的信息,就存在错误处理结果的风险,甚至导致不必要的损失,不给出不确定度的测量数据是没有意义的数据.线性拟合法利用从方法确认、实验室内质控和实验室间协作定值等数据,注重从整体上、通过数月、数年等一段期间反映样品检测精密度数据直接评估测量不确定度.     

Copula-Based Bivariate Return Period Analysis and Its Implication to Hydrological Design Event

In univariate frequency analysis, the return period of an event has a one-to-one correspondence with its characteristic value, and the response of the hydraulic structure to hydrological load expressed by the hydrological event is monotonic. Thus, the design criteria of the hydraulic structure can be equivalently represented by the return period of the hydrological event, and consequently, design event-based design parameters evaluated have been widely used in practical engineering. However, the monotonic correspondence between the return period of the hydrological event and the response of the hydraulic structure does not exist in the multivariate context, and hydrological load with a larger joint return period does not always produce a more unsafe response. Misunderstandings of concepts of return periods of hydrological event, and estimation of hydrological design events usually take place in multivariate frequency analysis. This study theoretically derives the relations between different types of joint return periods, joint return period and its marginal return periods, the occurrence of bivariate extreme events and their return periods, and then the theoretical framework is tested. Results from the case contribute to the understanding of bivariate return periods of hydrological event, and the results demonstrate that design criteria cannot be equivalently represented by joint return periods of hydrological load, and design parameters of the hydraulic structure should not be determined by multivariate hydrological design events.