川西亚高山3个优势树种细根形态特征

林木细根(直径2 mm)拥有庞大而复杂的分枝系统,在森林生态系统养分循环过程中发挥重要作用,因此研究不同树种细根构型形态对树种地下生态位分离、共存和森林生态系统功能过程具有重要意义.选取川西亚高山3个优势树种——岷江冷杉(Abies faxoniana)、粗枝云杉(Picea asperate)和红桦(Butula albosinensis),采用挖掘法采集完整的细根根系,依据根序分级方法,测定细根形态参数(直径、根长、比根长和比表面积).结果表明:细根形态在不同根序间差异显著,3个树种细根直径、根长随根序的升高而升高,比根长和比表面积随序级的升高而降低.不同树种间细根形态也表现出极显著差异,岷江冷杉、粗枝云杉和红桦细直径变化范围分别为0.31-0.85 mm、0.29-0.65 mm和0.23-0.55 mm,两个针叶树种(岷江冷杉和粗枝云杉)直径与根长均大于红桦.红桦的比根长和比表面积则高于两个针叶树种.综上所述,低级别根吸收能力更强而构建消耗更低;红桦比岷江冷杉和粗枝云杉根系吸收能力更强.     

内蒙古呼和浩特市大气TSP和PM_(10)中PAHs的健康风险评价

于2012—2013年6月和12月采集了内蒙古呼和浩特市大气颗粒物样品,用GC-MS分析测定其中16种PAHs的浓度,并用苯并(a)芘(Ba P)致癌、致突变等效浓度、终身致癌超额危险度和预期寿命损失3个指标评价了内蒙古呼和浩特市大气颗粒物TSP和PM_(10)中PAHs的人群健康风险。结果显示:内蒙古呼和浩特市大气颗粒物TSP和PM_(10)中PAHs对成人、儿童的日均暴露剂量范围分别为0.71×10~(-6)~2.01×10~(-6)、0.45×10~(-6)~1.28×10~(-6)和0.31×10~(-6)~2.41×10~(-6)、0.19×10~(-6)~1.15×10~(-6)mg·kg~(-1)·d~(-1);TSP和PM_(10)中PAHs对成人和儿童的终身致癌超额危险度范围分别为2.21×10~(-6)~6.24×10~(-6)、1.41×10~(-6)~3.97×10~(-6)和0.95×10~(-6)~7.47×10~(-6)、0.60×10~(-6)~4.75×10~(-6),终身致癌超额危险度均处于可接受水平范围内(10-4~10~(-6))。TSP和PM_(10)中PAHs对成人和儿童的预期寿命损失范围分别为13.74~38.78、8.752~24.70和5.88~46.39、3.74~29.54 min。     

Effect of ultra-micro powder Dendrobium officinale on the molecular diversity of intestinal bacteria in mice with spleen-deficiency constipation北大核心CSCD

This research aimed to study the effect of ultra-micro powder Dendrobium officinale on the molecular diversity of intestinal bacteria in mice with spleen-deficiency constipation, in order to provide scientific basis for ultra-micro D. officinale therapy. The mice with spleen-deficiency constipation in treatment groups were respectively given the traditional decoction of D. officinale and 50% dose ultra-micro powder D. officinale. The metagenome DNA of intestinal flora was extracted from intestinal contents. Then ARDRA analysis was made after PCR by universal primer of bacteria. The results showed that OTUs, Shannon index and Brillouin index were the same between the normal group and the 50% dose ultra-micro powder group, and between the model group and the traditional decoction group, but greater in the former two groups than the latter ones. The similarity coefficient (0.500 0) was bigger between the 50% dose ultra-micro powder group and the normal group than between the model group and the traditional decoction group, which was 0.181 8. Both cluster analysis and principal components analysis showed that the molecular diversity of intestinal microbiotia in mice of 50% dose ultra-micro powder group was the closest to that in the normal group. The results showed that the weakened molecular diversity of intestinal bacteria in mice with spleen-deficiency constipation can be regulated by the two kinds of D. officinale treatments to different extent. The efficacy of 50% dose ultra-micro powder D. officinale is better than the traditional decoction.     

两种有机酸存在下铜对中华圆田螺肝脏的氧化应激效应

为探讨不同水平EDTA和柠檬酸(CA)作用下沉积物中铜对底栖无脊椎动物生态毒理学效应,以中华圆田螺为受试生物,研究了肝脏中活性氧(ROS)、丙二醛(MDA)含量、超氧化物歧化酶(SOD)以及过氧化氢酶(CAT)活性的变化规律。研究结果表明:有机酸存在下,铜污染底泥可诱导中华圆田螺肝脏产生ROS。电子顺磁共振(EPR)技术得出的3组双重峰分裂谱线为典型的α-苯基-N-叔丁基甲亚胺-N-氧化物(PBN)捕获羟自由基(·OH)形成PBN/·OH的EPR波谱。有机酸存在下,低剂量铜(≤100 mg·kg-1)对MDA产量影响不显著。较高剂量铜暴露下,EDTA的存在抑制MDA产生,CA的添加则均使MDA含量增加。EDTA存在下铜可显著抑制中华圆田螺肝脏中SOD和CAT活性。相对而言,CA的加入可减缓高剂量铜暴露下中华圆田螺肝脏SOD与CAT酶活性的剧烈变化。     

A comparative study of particle size distribution from two oxygenated fuels and diesel fuel

Oxygenated fuels are known to reduce particulate matter (PM) emissions from diesel engines. In this study, 100% soy methyl ester (SME) biodiesel fuel (B100) and a blend of 10% acetal denoted by A-diesel with diesel fuel were tested as oxygenated fuels. Particle size and number distributions from a diesel engine fueled with oxygenated fuels and base diesel fuel were measured using an Electrical Low Pressure Impactor (ELPI). Measurements were made at ten steady-state operational modes of various loads at two engine speeds. It was found that the geometric mean diameters of particles from SME and Adiesel were lower than that from base diesel fuel. Compared to diesel fuel, SME emitted more ultra-fine particles at rated speed while emitting less ultra-fine particles at maximum speed. Ultra-fine particle number concentrations of A-diesel were much higher than those of base diesel fuel at most test modes.     

Ultrastructure of pedal muscle as a function of temperature in nacellid limpets

Temperature and mitochondrial plasticity are well studied in fishes, but little is known about this relationship in invertebrates. The effects of habitat temperature on mitochondrial ultrastructure were examined in three con-familial limpets from the Antarctic (Nacella concinna), New Zealand (Cellana ornata), and Singapore (Cellana radiata). The effects of seasonal changes in temperature were also examined in winter and summer C. ornata. Stereological methods showed that limpet pedal myocytes were 1–2 orders of magnitude smaller in diameter (≈3.5 μm) than in vertebrates, and that the diameter did not vary as a function of temperature. Mitochondrial volume density (Vv_(mt,f)) was approximately 2–4 times higher in N. concinna (0.024) than in the other species (0.01 and 0.006), which were not significantly different from each other. Mitochondrial cristae surface density (Sv_(im,mt)) was significantly lower in summer C. ornata (24.1 ± 0.50 μm² μm⁻³) than both winter C. ornata (32.3 ± 0.95 μm² μm⁻³) and N. concinna (34.3 ± 4.43 μm² μm⁻³). The surface area of mitochondrial cristae per unit fibre volume was significantly higher in N. concinna, due largely to the greater mitochondrial volume density. These results and previous studies indicate that mitochondrial proliferation in the cold is a common, but not universal response by different species from different thermal habitats. Seasonal temperature decreases on the other hand, leading preferentially to an increase in cristae surface density. Stereological measures also showed that energetic reserves, i.e. lipid droplets and glycogen in the pedal muscle changed greatly with season and species. This was most likely related to gametogenesis and spawning.     

轧钢企业作业场所职业危害因素分析

本文针对轧钢企业作业场所的职业危害因素进行辨识分析,并依据《职业病危害因素分类目录》对轧钢企业涉及的职业病类型、对应危害因素和作业场所分布进行总结,提出了相应的职业危害因素的控制措施。     

Extinction rate of discovered and undiscovered plants in Singapore

Extinction is a key issue in the assessment of global biodiversity. However, many extinction rate measures do not account for species that went extinct before they could be discovered. The highly developed island city–state of Singapore has one of the best-documented tropical floras in the world. This allowed us to estimate the total rate of floristic extinctions in Singapore since 1822 after accounting for sampling effort and crypto extinctions by collating herbaria records. Our database comprised 34,224 specimens from 2076 native species, of which 464 species (22%) were considered nationally extinct. We assumed that undiscovered species had the same annual per-species extinction rates as discovered species and that no undiscovered species remained extant. With classical and Bayesian algorithms, we estimated that 304 (95% confidence interval, 213–414) and 412 (95% credible interval, 313–534) additional species went extinct before they could be discovered, respectively; corresponding total extinction rate estimates were 32% and 35% (range 30–38%). We detected violations of our 2 assumptions that could cause our extinction estimates, particularly the absolute numbers, to be biased downward. Thus, our estimates should be treated as lower bounds. Our results illustrate the possible magnitudes of plant extirpations that can be expected in the tropics as development continues.     

汞矿区大气汞的流通量与汞干湿沉降研究

应用ＦｌｕｘＣｈａｍｂｅｒ技术评价汞矿,矿渣及附近土壤表面汞的流通量,表明,土壤表面汞的流通量平均为１７３．５ｎｇ．ｈ＾－１．ｍ＾－２,矿均为２３６．６ｎｇ．ｈ＾－１．ｍ＾－２,原矿平均为７０ｎｇ．ｈ＾－１．ｍ＾－２。     

A Framework for Evaluating the Effects of Human Factors on Wildlife Habitat: the Case of Giant Pandas

Abstract: To address the complex interactions between humans and wildlife habitat, we developed a conceptual framework that links human factors with forested landscapes and wildlife habitat. All the components in the framework are integrated into systems models that analyze the effects of human factors and project how wildlife habitat would change under different policy scenarios. As a case study, we applied this framework to the Wolong Nature Reserve in Sichuan Province (southwestern China), the largest home of the giant panda ( Ailuropoda melanoleuca ). We collected ecological and socioeconomic data with a combination of various methods ( field observations, aerial photographs, government documents and statistics, interviews, and household surveys) and employed geographic information systems and systems modeling to analyze and integrate the data sources. Human population size has increased by 66% and the number of households in the reserve has increased by 115% since 1975, when the reserve was established. During the same period, the quality and quantity of the giant panda habitat dramatically decreased because of increasing human activities such as fuelwood collection. Systems modeling predicted that under the status quo, human population in the reserve would continue to grow and cause more destruction of the remaining panda habitat, whereas reducing human birth rates and increasing human emigration rates would lower human population size and alleviate human impacts on the panda habitat. Furthermore, our simulations and surveys suggested that policies encouraging the emigration of young people would be more effective and feasible than relocating older people in reducing human population size and conserving giant panda habitat in the reserve.