Urban ozone control and atmospheric reactivity of organic gases

Control strategies for urban ozone traditionally have been based on mass reductions in volatile organic compounds (VOCs). Studies show, however, that some organic gas species (such as alkanes and alcohols) form an order of magnitude less ozone than equal mass emissions of others (such as alkenes and aldehydes). Chemically detailed photochemical models are used to assess uncertainty and variability in reactivity quantification. VOC control strategies based on relative reactivity appear to be robust with respect to nationwide variations in environmental conditions and uncertainties in the atmospheric chemistry. Control of selective organic gas species on the basis of reactivity can offer cost savings over traditional strategies.     

大气校正对九连山植被覆盖度。感估算的影响

以江西九连山保护区为例,利用基于归一化差异植被指数（NDVI）的像元二分法模型分别在TM 影像的 原始DN 值、表观反射率以及经过基于MORTRAN 辐射传输模型和经过简单传输模型的黑暗像元法校正后的地面 反射率的基础上对研究区的植被覆盖度进行提取,将所得4 类植被覆盖度的估算值与实测值进行比较,分析大气校 正对植被覆盖度。感估算的影响。结果表明,FLAASH 和DOS 两种大气校正方法虽校正原理不同,但通过对样地实 测值的拟合度来看,均能有效消除大气影响,有效提高植被覆盖度。感估算的精度;而辐射定标后的表观反射率却 与原始影像DN 值估算的植被覆盖度差异不明显,说明植被覆盖度估算精度的提高来源于大气校正作用,辐射定标 影响甚小。因此,在植被覆盖度较高的亚热带区域,有必要进行大气校正,以改善估算精度。     

Effects of trace gases and water vapor on the diffusion coefficient of polonium-218

The two-filter method described by Thomas and LeClare was used to investigate the effects of trace concentrations of nitric oxide and nitrogen dioxide in dry nitrogen on the diffusion coefficient of radium A (polonium-218). Charged radium A was neutralized in 10 parts per million (ppm) nitrogen dioxide in dry nitrogen, in 8.3 ppm nitric oxide in dry 92 percent nitrogen and 8 percent oxygen, and in nitrogen with 20 and 80 percent relative humidity. No neutralization was seen in dry nitrogen, dry oxygen, dry air, or 10 ppm nitric oxide in dry nitrogen. The diffusion coefficient of the neutral radium A species was found to be 0.079 square centimeters per second, regardless of the relative humidity of the nitrogen gas atmosphere. Lower values were observed for charged species.     

Identification of polymers as major components of atmospheric organic aerosols

Results from photooxidation of aromatic compounds in a reaction chamber show that a substantial fraction of the organic aerosol mass is composed of polymers. This polymerization results from reactions of carbonyls and their hydrates. After aging for more than 20 hours, about 50% of the particle mass consists of polymers with a molecular mass up to 1000 daltons. This results in a lower volatility of this secondary organic aerosol and a higher aerosol yield than a model using vapor pressures of individual organic species would predict.     

The early faint sun paradox: organic shielding of ultraviolet-labile greenhouse gases

Atmospheric mixing ratios of approximately 10(-5 +/- 1) for ammonia on the early Earth would have been sufficient, through the resulting greenhouse warming, to counteract the temperature effects of the faint early sun. One argument against such model atmospheres has been the short time scale for ammonia photodissociation by solar ultraviolet light. Here it is shown that ultraviolet absorption by steady-state amounts of high-altitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing.     

Copper porphyrins in deep-sea sediments: a possible indicator of oxidized terrestrial organic matter

Copper porphyrins have been isolated from deep-sea sediments collected during six legs of the Deep Sea Drilling Project-International Program of Ocean Drilling. These pigments are present in depositional areas receiving high inputs of terrestrially derived oxidized organic matter. Such areas include the Black Sea, the Bay of Biscay, the Blake-Bahama Basin, and slumped Miocene deposits off Cape Bojador on the west coast of Africa.     

有机蔬菜质量安全追溯管理系统的研究与设计

可追溯系统是构建食品安全体系的一个重要组成部分。运用条码技术和计算机组件技术,实现了有机蔬菜产品的安全生产控制,构建了基于.NET构架的有机蔬菜质量安全追溯管理系统。使用该系统可以提高基地生产管理水平,增强消费者的农产品安全意识。     

黔东南不同植被类型下土壤养分及 颗粒态有机碳差异分析

以贵州黔东南不同植被类型下森林土壤为研究对象,通过“外调查与室内分析相结合的方法,对黔东 南不同植被类型林下土壤混合样(0耀20 cm）养分含量和土壤酸度进行研究。结果表明院4 种典型植被土壤均呈较强的 酸性,pH 值在4.46耀5.38 之间。4 种植被类型林下土壤有机质大小关系为阔叶混交林(52.16 g/kg）>杉木林(50.16 g/ kg）>针阔混交林(40.07 g/kg）>马尾松林(30.61 g/kg）;全氮含量最低的是马尾松林(1.13 g/kg）,最高的是阔叶混交林 (2.31 g/kg）。全磷与全氮大小关系均表现为院阔叶混交林>针阔混交林>杉木林>马尾松林;土壤全钾含量依次为阔叶 混交林(14.33 g/kg）>杉木林(12.30 g/kg）>马尾松林(11.35 g/kg）>针阔混交林(10.5 g/kg）;不同植被类型林下土壤颗粒 态有机碳大小为院马尾松林>针阔混交林>阔叶混交林>杉木林。     

Survival of mammals breathing organic liquids equilibrated with oxygen at atmospheric pressure

Because oxygen and carbon dioxide are very soluble in certain silicone oils and fluorocarbon liquids, these liquids will support respiration of mammals. Mice and cats respiring silicone oil die shortly after return to air breathing, while those breathing fluorocarbon survive for weeks. The respiration of mice is optimally supported by these organic liquids at about 20 degrees C. In cats, arterial oxygenation is excellent, but there is some impairment of carbon dioxide elimination. All animals have suffered some pulmonary damage from breathing fluorocarbon liquids. Continued investigation of organic fluid respiration may lead to development of a safe method to support the respiration of man by liquids equilibrated with gases at atmospheric pressure.     

大气CO_2浓度升高对繁茂膜海绵阻留海水中有机碳功能的影响

在实验室条件下,研究了大气CO2浓度升高对最低等多细胞动物海绵过滤功能影响。在模拟大气CO2浓度升高的生态系统中,考察了CO2浓度为387、500、750、1000mg/L的环境下,繁茂膜海绵Hymeniacidon perlevis阻留灭菌海水中总有机碳(TOC)的能力。结果表明:在模拟CO2浓度为387、500、750、1000mg/L的条件下,繁茂膜海绵在16 h内清除海水中TOC的效率分别为55.8%、67.6%、50.0%和15.4%,在24h对TOC的平均阻留率分别为(1.90±0.20)、(2.13±0.06)、(1.69±0.08)、(0.43±0.11)mg/(h·g海绵),平均清除率分别为(0.025±0.002)、(0.033±0.001)、(0.019±0.001)、(0.004±0.001)mL/(h·g海绵),由此可见,大气CO2浓度从约387mg/L升高至500mg/L时,促进了繁茂膜海绵阻留海水中TOC的能力,当浓度升高至750 mg/L时,抑制了繁茂膜海绵阻留TOC的能力,当浓度进一步升高至1000mg/L时,导致繁茂膜海绵几乎丧失了阻留海水中TOC的能力。本研究结果可为大气CO2浓度升高对潮间带海绵过滤功能影响及其由此可能导致的近岸海域生态问题提供了参考。     

植被恢复对退化红壤水稳性团聚体有机碳的影响

为从微观角度揭示植被恢复对土壤结构的影响,采用野外调查与室内分析相结合的方法,研究南方红壤退化地3种典型植被恢复类型[马尾松与阔叶复层林(PB)、木荷×马尾松混交林(SP)、阔叶林(BF)]土壤(0~60 cm土层)水稳性团聚体有机碳分布特征及其对总有机碳的贡献率。结果表明:土壤水稳性团聚体含量及其有机碳贡献率随团聚体粒径的减小总体呈"W"或"N"字分布;不同粒径水稳性团聚体含量以粒径<0.05 mm占优势,而大粒径团聚体含量在湿筛过程中大幅降低,表明大粒径团聚体在水的浸润中更易受到影响;上层土壤(0~40 cm)水稳性大团聚体(粒径>0.25 mm)总含量均以PB最高,而在下层土壤(40~60 cm)3种植被恢复类型较为接近(48.80%~51.64%)。土壤总有机碳和水稳性团聚体有机碳含量大小顺序均表现为PB>SP>BF,随着土层深度的增加,两者均呈下降趋势;水稳性大团聚体有机碳含量总体高于微团聚体(粒径<0.25 mm),说明有机碳对水稳性大团聚体的形成具有积极作用。不同林分土壤团聚体有机碳贡献率均以粒径0.05~0.25 mm最小,且PB中粒径>2.00 mm的团聚体有机碳贡献率显著高于SP和BF(P<0.05)。保留密度大、灌木(草)层盖度高的马尾松与阔叶复层林土壤水稳性大团聚体与团聚体有机碳含量更高,对土壤结构改善与功能恢复效果更好。     

大气CO_2浓度升高对繁茂膜海绵阻留海水中有机碳功能的影响

在实验室条件下,研究了大气CO2浓度升高对最低等多细胞动物海绵过滤功能影响。在模拟大气CO2浓度升高的生态系统中,考察了CO2浓度为387、500、750、1000mg/L的环境下,繁茂膜海绵Hymeniacidon perlevis阻留灭菌海水中总有机碳(TOC)的能力。结果表明:在模拟CO2浓度为387、500、750、1000mg/L的条件下,繁茂膜海绵在16 h内清除海水中TOC的效率分别为55.8%、67.6%、50.0%和15.4%,在24h对TOC的平均阻留率分别为(1.90±0.20)、(2.13±0.06)、(1.69±0.08)、(0.43±0.11)mg/(h·g海绵),平均清除率分别为(0.025±0.002)、(0.033±0.001)、(0.019±0.001)、(0.004±0.001)mL/(h·g海绵),由此可见,大气CO2浓度从约387mg/L升高至500mg/L时,促进了繁茂膜海绵阻留海水中TOC的能力,当浓度升高至750 mg/L时,抑制了繁茂膜海绵阻留TOC的能力,当浓度进一步升高至1000mg/L时,导致繁茂膜海绵几乎丧失了阻留海水中TOC的能力。本研究结果可为大气CO2浓度升高对潮间带海绵过滤功能影响及其由此可能导致的近岸海域生态问题提供了参考。     

Influence of carbonic anhydrase activity in terrestrial vegetation on the 18O content of atmospheric CO2

The oxygen-18 (18O) content of atmospheric carbon dioxide (CO2) is an important indicator of CO2 uptake on land. It has generally been assumed that during photosynthesis, oxygen in CO2 reaches isotopic equilibrium with oxygen in 18O-enriched water in leaves. We show, however, large differences in the activity of carbonic anhydrase (which catalyzes CO2 hydration and 18O exchange in leaves) among major plant groups that cause variations in the extent of 18O equilibrium (theta(eq)). A clear distinction in theta(eq) between C3 trees and shrubs, and C4 grasses makes atmospheric C18OO a potentially sensitive indicator to changes in C3 and C4 productivity. We estimate a global mean theta(eq) value of approximately 0.8, which reasonably reconciles inconsistencies between 18O budgets of atmospheric O2 (Dole effect) and CO2.     

植被更替及植果年限对土壤有机质和酶活性的影响

土壤有机质及酶活性是反映植被更替对土壤质量作用与影响较为敏感的指标,对分析制约地区苹果产业可持续发展因素具有重要意义。在彬县果区土壤及地形条件与管理水平基本一致的条件下,以农田土壤(对照)与8年(幼龄)、21年(老龄)果园为研究对象,研究其0～40 cm土层深度内的有机质、过氧化氢酶活性、脲酶活性、碱性磷酸酶活性的变化趋势。结果表明,土壤有机质、脲酶和碱性磷酸酶活性随土层深度的增加而减少。在0～40 cm土层范围内,农田演替为果园,降低了土壤有机质含量、过氧化氢酶和碱性磷酸酶活性,增加了土壤脲酶活性。随着种植年限的增加,有机质含量在0～20 cm土层出现累积趋势,过氧化氢酶活性减少,而碱性磷酸酶和脲酶在剖面上呈现不同程度的递减趋势。因此,在0～40 cm土层植被更替及植果年限对土壤生物质量影响明显,可能会对果树生长产生影响。     

江苏滨海湿地不同植被演替阶段土壤有机碳分布特征

对江苏滨海湿地土壤有机碳的分布特征进行研究,阐明了植被演替和土壤理化性质对土壤有机碳分布的影响,对探讨今后如何增加滨海湿地的"碳汇"能力具有重要的意义。结果表明,水平方向上,有机碳的分布特征表现为:光滩米草群落芦苇群落刺槐群落碱蓬群落。在0~10 cm层,土壤有机碳平均含量为20.84 g·kg-1,其中米草群落土壤有机碳含量显著高于其他几种类型;10~25 cm和25~40 cm土层,土壤有机碳平均含量分别为18.66 g·kg-1和19.15 g·kg-1,光滩含量最高。垂直方向上,0~10 cm层土壤有机碳含量均最高,光滩土壤有机碳含量随土层深度增加而增加;碱蓬和米草群落湿地土壤有机碳含量的垂直分布特征则相反;刺槐群落和芦苇群落湿地土壤有机碳含量分布表现为,表层含量最高,中间土层含量最低。土壤有机碳含量与土壤容重具有极显著的负相关关系,而与C/N和盐分呈显著的正相关关系。虽然研究结果中土壤有机碳含量与其他因子的相关性不显著,但是土壤各理化性质间的相互作用会间接影响有机碳含量的分布。     

植被更替及植果年限对土壤有机质和酶活性的影响

植被更替对土壤质量造成的作用和影响较为深远,土壤有机质及酶活性则属于能够较好反 映这种作用和影响的指标。基于此,本文基于地形、土壤、管理水平基本一致条件,围绕10 年果园、20 年果园、农田土壤开展了针对性研究,通过对比0~40cm 土层深度内的碱性磷酸酶活性、脲酶活性、过 氧化氢酶活性、有机质变化趋势,研究明确了植被更替及植果年限带来的影响,果树生长因此受到的 影响也得以明确。     

Multiple stable isotopes used to trace the flow of organic matter in estuarine food webs

The use of a combination of the stable isotopes of sulfur, carbon, and nitrogen allows the flow of organic matter and trophic relations in salt marshes and estuaries to be traced while eliminating many ambiguities that accompany the use of a single isotopic tracer. Salt-marsh grasses take up the isotopically light sulfides formed during sulfate reduction, and the transfer of this light sulfur through the marsh food web is illustrated with data on the ribbed mussel (Geukensia demissa) from various locations in a New England marsh. The multiple isotope approach shows that this filter feeder consumes both marsh grass ( Spartina) detritus and plankton, with the relative proportions of each determined by the location of the mussels in the marsh.