湘中丘陵区不同经营目标毛竹林年龄结构、生物量分配与碳贮量格局

经营模式对毛竹林生物量、碳贮量具有重要影响。研究了湘中丘陵区毛竹笋用林(Ⅰ)、笋材兼用林 (Ⅱ)和材用林(Ⅲ) 3种不同经营目标下的竹林年龄结构、生物量分配及碳贮量格局。结果表明：应减少1～2 a、增加5～6 a生竹的留养比例,控制达到1～2 a、3～4 a、5～6 a各占1/3左右的立竹年龄结构。不同层次生物量表现为乔木层＞凋落物层＞林下植被层,毛竹笋用林经营有利于增加乔木层生物量。乔木层生物量及所占比例分别为5183～5566 t/hm2、8895%～9293%,林下植被层生物量及所占比例分别为154～258 t/hm2、258%～443%,凋落物层生物量及所占比例分别为269～386 t/hm2、449%～662%。毛竹林总碳贮量排队顺序为Ⅱ（14263 t/hm2）＞Ⅰ（13389 t/hm2）＞Ⅲ（13004 t/hm2）,笋材兼用林有利于提高竹林碳贮能力。不同层次碳贮量排列顺序总体均表现为土壤层＞乔木层＞凋落物层＞林下植被层。湘中丘陵区毛竹林生物量、碳贮量较低,应提高集约经营水平     

Determining the age of cyclomorphic rodents: Functional-ontogenetic determination,ecological aspects

Functional-ontogenetic determination of age-dependent dental changes (ADCs) in voles has been demonstrated. The relationship between ADCs and the functional state of animals has been analyzed. A scheme and a table for determining individual chronological and biological ages in the bank vole (Clethrionomys glareolus Sch.) are proposed, which markedly improve the accuracy of results. Cases of rodent maturation and breeding in winter are considered.     

大气挥发性有机物的日变化特征及在臭氧生成中的作用——以广州夏季为例

为了得到实时的大气挥发性有机物(VOCs)浓度组成和日变化特征,2006年夏季在广州市区内高约55m的楼顶采用在线的气相色谱仪进行了为期一个月的观测.结果表明,影响城市VOC含量的物种以及对臭氧生成有重要贡献的典型物种的日变化存在不同的特征.烷烃类和烯烃类物种出现早晚高峰值,估计主要与机动车排放有关,芳香烃除了与交通排放有关,还受到溶剂挥发的影响,早晨的峰值晚于交通高峰时间.异戊二烯在正午时间出现一天的单峰值,主要来自于天然源排放.乙苯和间对二甲苯的比值被用来表征采样点上气团光化学反应的进程,通常情况下,广州市区点气团经历的光化学进程越久,臭氧浓度越高.     

Small Populations and Offspring Sex-Ratio Deviations in Eagles

Abstract:  Stochastic variation of sex ratio has long been appreciated as a potential factor driving small populations to extinction, but it is not the only source of sex-ratio bias in small populations. We examined whether some consequences of sex allocation could affect extinction risk in small populations of size-dimorphic birds such as eagles. We report variations in sex ratio at fledging from a long-term study of a declining population of Spanish Imperial Eagles ( Aquila adalberti ). Nestling sex-ratio deviation apparently was mediated by age of breeders, whereas territory quality had no obvious effect. Adult–adult pairs produced the same proportion of both sexes in high- or low-density situations, but pairs with at least one member in nonadult plumage class produced more males. As the population declined over a period of years, the proportion of breeders with immature plumage increased; consequently, the proportion of fledgling males increased. However, when population density was high, the proportion of breeders with immature plumage decreased and more female offspring were produced. This relationship between population density, composition of breeder age, and fledgling sex ratios allowed us to make predictions of extinction risk due to nonstochastic deviations of sex ratio in small, declining populations. In the study population, on the basis of the Vortex simulation results, an estimated reduction of 42.5% in predicted mean time to extinction was attributed solely to biased sex ratio.     

Improved research-scale foam generator design and performance characterization

The release of a cryogenic, flammable liquid, such as LNG, poses a threat to individuals in the area of the release as well as responders who attempt to limit the damage of the release. The most common mitigation technique is high-expansion foam which can be used to blanket the liquid, reducing the accumulation of flammable vapor above the pool through a number of different mechanisms. Despite the effectiveness of high-expansion foam blanketing, there are many aspects of the interaction between foam and LNG that are unknown. A lab-scale high-expansion foam generator has been developed to allow the study of those interactions. Additionally, the novel foam generator design addresses many of the drawbacks of industrial-scale foam generators and allows researchers better control of the foam, while producing foam at rates that are conducive to lab applications. Foam was produced using the generator and expansion ratio and foam stability were measured to determine the quality. The generator was able to produce foam with expansion ratio between 298 and 892 that collapsed at an average rate of 0.4 cm per minute. This quality of the foam is comparable to industrial-scale foam generators and the foam production rate is between 1.2 and 2.2 m³/min, which fits lab-scale needs. The foam generator can also be used with other types of non-firefighting foam, such as decontamination foam for chemical, biological, or nuclear decontamination.     

基于碳同位素组成的大气NMHCs光化学寿命研究

利用热解析-气相色谱-同位素质谱联用仪测定了兰州市冬季和夏季昼夜大气非甲烷烃(NMHCs)的稳定碳同位素组成.结果表明,兰州市冬季大气NMHCs的δ13C值为-30.5‰～-24.3‰,夏季为-31.9‰～-24.2%,受燃煤烟气排放的影响,冬季大气NMHCs的δ13C值明显大于夏季;冬季大气NMHCs的δ13C值夜晚大于白天,夏季不同时间点C4、C5化合物的同位素值相差不大,正己烷和正庚烷的δ13C值白天比夜晚要高.利用"碳氢化合物同位素时钟"计算出正己烷和1-丁烯在兰州市夏季大气中的平均光化学寿命分别约为6d和25min.     

Productivity of mosses and organic matter accumulation in the litter of sphagnum larch forest in the permafrost zone

Productivity of the moss cover and necromass accumulation in the litter of a sphagnum larch forest have been estimated on the basis of tree age. It has been shown that the total carbon stock in the litter of a 100-year-old stand, including organic matter not destroyed by fire, exceeds the corresponding value for the tree stand itself by more than an order of magnitude. The accumulation of organic matter on the soil surface inhibits the growth of larch. In particular, this factor impairs hydrothermal conditions in the soil and causes a rise of the permafrost table; as a consequence, lower layers of the root system die off.     

大熊猫主食竹种秆龄鉴定及种群动态评估

四川西南部和西北部中山、亚高山森森下，竹源丰富，其中：拐棍竹和冷箭竹是大熊猫的主食竹种，作者１９８２－１９８７年进行竹类生态研究；通过固定样方观察和带标志茎秆记录分析，发现竹杆和笋箨的颜色，以及主枝叶鞘与枝节数的变化和竹子秆龄的增长密切相关，可以作为鉴定竹秆年龄的依据。根据竹子的秆龄结构，应用负指数函数模型，可以估算竹子种群的增长量和死亡率，评估竹子的种群动态变化，可为主管部门制定保护大熊猫规划规     

循环式活性污泥法中好氧选择区的运行条件研究

研究了循环式活性污泥法好氧生物选择区的停留时间和整个系统中泥龄、污泥负荷、曝气时间等运行参数对选择区内微生物吸附性能的影响。结果表明 ,选择器停留时间 3 0 min,系统泥龄 9～ 15 d,曝气 2 h,污泥有机负荷为 0 .3 g CODCr/(g ML SS·d)左右时 ,选择器中微生物的吸附性能最优 ,可去除进水中 90以上的 CODCr。