石油类污染物自然衰减能力现场试验验证研究

在北京地区某加油站开展的前期石油类污染物自然衰减现场试验的基础上,进一步开展了验证试验,结果表明本次试验得到的挥发性有机物(VOCs)变化趋势及O2、CO2含量沿土壤深度分布和前期试验结果呈现相同的规律,说明基于自然衰减法设计实施的加油站现场试验检测分析结果可靠,试验方法具有合理性、可操作性及可重复性.进一步的理论分析对前期试验结果进行了验证,得出以下结论:(1)通过氧平衡和碳平衡计算对加油站土壤内的自然衰减方式进行评价,验证了该加油站地下土壤中实际发生的微生物降解既有需氧降解也有厌氧降解;(2)利用有机物的一级衰减模型对该污染现场土壤中石油类污染物的降解速率和半衰期进行计算表明,2次试验计算得到的石油类污染物的半衰期基本一致,该污染现场石油类污染物的半衰期为50 d左右;(3)在此基础上,对该加油站包气带土壤的自然衰减能力和环境质量进行评价,2次试验结果均表明该污染现场在自然衰减的作用下已经不存在环境风险.     

有风条件下剧院火灾自然排烟效果分析

为研究某剧院休息厅的自然排烟效果的问题,根据建筑特征设计6个火灾场景。运用理论计算和数值模拟的方法,分别研究不同开窗位置、开窗面积以及环境风速对火灾时的热流场和烟气蔓延的影响。结果表明：不同开窗位置达到临界值的时间为顶窗〉东西立面侧窗〉北立面侧窗;有风条件下3.5%的开窗面积的排烟效果和无风时6%的开窗面积的排烟效果相当。结论是考虑当地环境风速,选择顶部5%和东西侧3.5%开窗方式,增强该剧院的自然排烟效果。     

滦河水体溶解性有机物的综合分级表征及其混凝去除过程

天然水体溶解性有机物(DOM)是微污染物的潜在载体,是消毒副产物的主要前驱物,自身又可能成为微污染物,因此研究其内在特性和去除机理有着重要的基础性科学意义.本研究综合利用化学、物理分级方法(即树脂和超滤分级法),对中国北方典型饮用水源--滦河水体的DOM进行全面分级表征.此水体DOM基本化学分级特征是憎水酸(HoA)、亲水性物质(HiM)含量较高,且具有季节稳定性;其物理分级特征是分子量＜1 kDa及3 kDa～10 kDa的组分含量较高,也表现出一定的时间稳定性.选用工业聚合铝(PAC)研究此DOM的基本混凝特征和内在混凝机理,结果表明,强憎水部分HoA及3 kDa～10 kDa间的有机物较易被去除,而较大分子量范围10 kDa～30 kDa间的有机物去除率较低,说明混凝过程中此DOM的物理性质不起主要作用,而化学性质更为重要.特别对DOM各组分作进一步(结合)分级研究,发现HoA主要在＞10 kDa范围.＜1 kDa的有机物中主要为HiM,但其中还含有HoA和弱憎水酸(WHoA),这使特定条件下部分＜1 kDa有机物被混凝去除成为可能.另外,HoA中按分子量大小仍可分为易去除和难去除部分,但分布不连续,易去除部分在3 kDa～10 kDa和＞30 kDa区间,而其10 kDa～30 kDa部分较难去除,说明可能存在其他结构性影响因素,值得深入研究.     

乐果对秀丽隐杆线虫生活史特征的影响

采用一种半流体培养基"挂滴法"对线虫进行培养和生命表实验,研究了低剂量暴露下乐果对秀丽隐杆线虫生活史特征的影响。在半致死浓度1/10 LC50、1/100 LC50、1/1000 LC50暴露剂量下(分别为7、0.7、0.07 mmol·L-1)染毒4 h。结果表明,0.7和7 mmol·L-1暴露组线虫的总繁殖率(TFR)分别为260.60、203.80,明显低于对照组(299.23,P0.05);净增殖率(R0)分别为240.29、147.67,明显低于对照组(298.67,P0.05);内禀增长率(rm)分别为1.342 d-1、1.233 d-1,明显低于对照组(1.387 d-1,P0.05);而0.07 mmol·L-1暴露组线虫的总繁殖率为293.84,净增殖率为286.60,与对照组比差异都没有统计学意义(P0.05)。在上述浓度范围,线虫的总繁殖率(TFR)、净增殖率(R0)和内禀增长率(rm)都随乐果浓度的升高而降低,并存在剂量效应关系。研究同时发现0.07 mmol·L-1暴露组线虫的内禀增长率为1.405 d-1,明显高于对照组(P0.05)。研究结论认为一定剂量的乐果使线虫的繁殖力降低;而低剂量暴露则对内禀增长率具有毒物兴奋效应。本文选择的3个指标TFR、R0、rm对低剂量下乐果暴露的响应敏感。     

Tradeoffs between forestry resource and conservation values under alternate policy regimes: A spatial analysis of the western Canadian boreal plains

An important element of resource management and conservation is an understanding of the tradeoffs between marketed products, such as timber, and measures of environmental quality, such as biodiversity. In this paper, we develop an integrated economic-ecological spatial optimization model that we then apply to evaluate alternate forest policies on a 560,000 km² study region of managed boreal forest in Alberta and British Columbia, Canada. The integrated model incorporates dynamic forest sector harvesting, current levels of oil and gas sector development, coarse-filter or habitat-based old forest indicators, a set of empirical forest bird abundance models, and statistical models of the natural and current fire regimes. Using our integrated model, economic tradeoff curves, or production possibility frontiers, are developed to illustrate the cost of achieving coarse-filter targets by a set time (50 years) within a 100-year time horizon. We found levels of ecological indicators and economic returns from the timber industry could both be increased if spatial constraints imposed by the current policy environment were relaxed; other factors being equal, this implies current policy should be revised. We explore the production possibility frontier's relationship to the range of natural variation of old forest habitat, and show how this range can be used to guide choices of preferred locations along the frontier. We also show that coarse-filter constraints on the abundance of certain habitat elements are sufficient to satisfy some fine-filter objectives, expressed as the predicted abundances of various species of songbirds.     

两种光照生境下4种常绿阔叶树的单位叶面积干重、光合能力与化学防御物质含量比较

亚热带常绿阔叶林下分布着可塑性强的耐荫植物,其叶片应对外界干扰的防御对策至少有物理性防御和化学性防御两种,这两种防御代价在一定的昆虫取食压力下在理论上应该存在权衡.为检验这种权衡是否普遍存在,分别测定了重庆缙云山4个常绿物种——光叶山矾(Symplocos lancifolia)、四川山矾(S.setchuensis)、四川毛蕊茶(Camellialawii)和细枝柃(Eurya loquaiana)在林窗和林下两种对照光环境下个体叶片的光饱和下的净光合速率、叶面积干重和部分化学防御物质含量.结果表明,4个物种生活在林窗的个体单位叶面积干重、叶片氮含量和单位面积净光合速率通常高于林下的个体,但是单位质量和单位面积的总酚含量和C/N值却低于林下的个体.蛋白质和非结构性碳水化合物含量在不同生境中没有显著差异.因为不同物种叶片对光照条件的响应不同,不同参数的变化在两种生境间的差异并不完全一致.本研究结果在一定程度上暗示了物种在林窗和林下分别倾向于采取物理和化学性防御对策,并初步证实了两种防御强度之间存在权衡关系.图4参40     

天然沸石对农田退水中氨氮的去除

利用静态吸附实验研究了沸石颗粒大小、氨氮初始浓度、接触时间及Na+离子浓度等因素对天然白银沸石去除模拟黄灌区农田退水中氨氮(NH4+-N)效果的影响,同时研究了吸附等温线特征,并考察了其吸附机理.研究结果表明,沸石颗粒大小、接触时间及NH4+和Na+初始浓度对NH4+-N交换容量都会产生一定影响;根据复相关系数(R2),NH4+-N的吸附等温线更符合三参数等温线模型;而对于两参数等温线模型,Langmuir模型比Freundlich模型能更好地描述NH4+-N在天然沸石上的离子交换过程;NH4+-N吸附实验数据与Elovich模型拟合最好(R2≥0.9766).研究结果表明了天然白银沸石是一种适合NH4+-N去除的离子交换剂,可用于黄灌区农田退水中NH4+-N的去除.     

Challenges to interdisciplinary research in ecosystem-based management

Despite its necessity, integration of natural and social sciences to inform conservation efforts has been difficult. We examined the views of 63 scientists and practitioners involved in marine management in Mexico's Gulf of California, the central California coast, and the western Pacific on the challenges associated with integrating social science into research efforts that support ecosystem-based management (EBM) in marine systems. We used a semistructured interview format. Questions focused on how EBM was developed for these sites and how contextual factors affected its development and outcomes. Many of the traditional challenges linked with interdisciplinary research were present in the EBM projects we studied. However, a number of contextual elements affected how mandates to include social science were interpreted and implemented as well as how easily challenges could be addressed. For example, a common challenge is that conservation organizations are often dominated by natural scientists, but for some projects it was easier to address this imbalance than for others. We also found that the management and institutional histories that came before EBM in specific cases were important features of local context. Because challenges differed among cases, we believe resolving challenges to interdisciplinary research should be context specific.     

Effects of flow regimes altered by dams on survival, population declines, and range-wide losses of California river-breeding frogs

Widespread alteration of natural hydrologic patterns by large dams combined with peak demands for power and water delivery during summer months have resulted in frequent aseasonal flow pulses in rivers of western North America. Native species in these ecosystems have evolved with predictable annual flood-drought cycles; thus, their likelihood of persistence may decrease in response to disruption of the seasonal synchrony between stable low-flow conditions and reproduction. We evaluated whether altered flow regimes affected 2 native frogs in California and Oregon (U.S.A.) at 4 spatial and temporal extents. We examined changes in species distribution over approximately 50 years, current population density in 11 regulated and 16 unregulated rivers, temporal trends in abundance among populations occupying rivers with different hydrologic histories, and within-year patterns of survival relative to seasonal hydrology. The foothill yellow-legged frog (Rana boylii), which breeds only in flowing water, is more likely to be absent downstream of large dams than in free-flowing rivers, and breeding populations are on average 5 times smaller in regulated rivers than in unregulated rivers. Time series data (range = 8 - 19 years) from 5 populations of yellow-legged frogs and 2 populations of California red-legged frogs (R. draytonii) across a gradient of natural to highly artificial timing and magnitude of flooding indicate that variability of flows in spring and summer is strongly correlated with high mortality of early life stages and subsequent decreases in densities of adult females. Flow management that better mimics natural flow timing is likely to promote persistence of these species and others with similar phenology.     

基于空气负离子浓度的建筑室内空气清洁度评价

对深圳某办公楼部分房间的空气负离子浓度分布进行了观测研究,利用空气离子单极系数和安倍空气离子评价指数对不同设备制冷的办公室空气质量进行了评价分析。结果表明:自然通风状态下的空气清洁度比机械通风状态下高,利用可再生能源制冷技术的室内空气质量比普通空调制冷技术的好,放置负离子发生器对室内空气质量有显著提高。因此提高室内负离子浓度可以创造舒适的空气环境,并建议把空气负离子浓度列为室内环境的监测和评价指标,为今后城乡建设规划、城市林业规划和环境能源保护提供科学依据和设计思路。