Carbon monoxide in rainwater

Concentrations of carbon monoxide in rainwater collected at widely diverse locations show up to a 200-fold supersaturation relative to the partial pressure of the gas in the atmosphere. These results indicate the existence of an additional natural source of carbon monoxide not heretofore considered. Production of carbon monoxide in clouds is tentatively attributed to the photochemical oxidation of organic matter or the slight dissociation of carbon dioxide induced by electrical discharges, or both. Methane concentrations measured in the same rainwater show that the partitioning of this gas, unlike that of carbon monoxide, is very close to a state of equilibrium.     

Carbon monoxide balance in nature

Consideration of the steady-state equations for stable carbon monoxide and for radioactive carbon monoxide in the troposphere leads to the conclusion that carbon monoxide is produced at a rate of 5x10(15) grams per year, a value some 25 times greater than the rate of carbon monoxide production from combustion. The concomitant residence time for carbon monoxide is 0.1 year, in agreement with a previous estimate of Weinstock. Hydroxyl radicals are shown to account for both the production of this large amount of carbon monoxide by methane oxidation and for its removal by carbon monoxide oxidation. The average concentration of hydroxyl radicals in the troposphere required to achieve this effect is 2.3x10(6) molecules per cubic centimeter, with a daytime concentration of twice that. Levy and McConnell, McElroy, and Wofsy have deduced concentrations of hydroxyl radicals in the troposphere of the same magnitude from purely photochemical considerations, in support of this model.     

Carbon monoxide in green plants

Green plants grown in a closed, illuminated system liberate small quantities of carbon monoxide. Similarly, finely divided powder and chlorophyll extracts of green plants, when illuminated in an environment of oxygen and water, will yield small quantities of carbon monoxide as well as certain aldehydes. The component of the light spectrum which is absorbed in photosynthesis (480 to 680 mmicro) was found to be responsible for the CO and aldehyde phenomena.     

Carbon monoxide measurements in the troposphere

During the second flight of the space shuttle, the measurement of air pollution from satellites (MAPS) experiment in the OSTA-1 payload acquired approximately 35 hours of radiometric measurements of the carbon monoxide mixing ratio in the middle troposphere, upper troposphere, and lower stratosphere. A gas filter radiometer operating in the 4.67-micrometer band was used to acquire the data over the region from 38 degrees N to 38 degrees S during both daytime and nighttime. The performance of the measurement system was excellent. The data reduced to date indicate the presence of significant gradients in the middle tropospheric carbon monoxide mixing ratio with both latitude and longitude over the North Atlantic, the Mediterranean Sea, and the Middle East. On the basis of comparisons with directly measured values, the accuracy of the measurements is approximately 15 percent. Comparisons of data taken on successive orbits over the same geographic region indicate that the repeatability of the measurements is approximately 5 percent.     

Carbon monoxide on jupiter and implications for atmospheric convection

A study of the equilibrium and disequilibrium thermochemistry of the recently discovered carbon monoxide on Jupiter suggests that the presence of this gas in the visible atmosphere is a direct result of very rapid upward mixing from levels in the deep atmosphere where the temperature is about 1100 degrees K and where carbon monoxide is thermodynamically much more stable. As a consequence the observed carbon monoxide mixing ratio is a sensitive function of the vertical eddy mixing coefficient. We infer a value for this latter coefficient which is about three to four orders of magnitude greater than that in the earth's troposphere. This result directly supports existing structural and dynamical theories implying very rapid convection in the deep Jovian atmosphere, driven by an internal heat source.     

Carbon monoxide: residence time in the atmosphere

A lower limit of 0.1 year for the residence time of carbon monIoxide in the atmosphere is derived from radiocarbon measurements. The action of certain microorganisms and atmospheric photochemical reactions are possible mechanisms for the removal of carbon monoxide. This value can be compared with 2.7 years, a value deduced from estimated rates of carbon monoxide production and global measurements of atmospheric concentrations of carbon monoxide.     

Carbon monoxide and air pollution from automobile emissions in New York City

Local business-day traffic determines the diurnal carbon monoxide concentrations at individual sites in Manhattan. Concentrations during the day can be predicted from readings taken in early morning.     

Carbon monoxide and nitric oxide consumption in polluted air: the carbon monoxide-hydroperoxyl reaction

A recent laboratory measurement of the ratio of the rate constant for the reaction CO + HO (2) --> C0(2) + OH relative to that for H + HO(2) --> 2OH indicates that the former reaction is probably faster than CO + OH --> CO(2) + H. On this basis a simple analysis is given showing that the calculated lifetime of nitric oxide in polluted atmospheres would be appreciably longer than that estimated on the assumption that the carbon monoxide-hydroperoxyl reaction may be neglected. A fast carbon monoxide-hydroperoxyl reaction implies that the cyclic consumption of carbon monoxide (an atmospheric sink) could occur even with no nitric oxide present.     

Carbon dioxide activation at the Ni,Fe-cluster of anaerobic carbon monoxide dehydrogenase

Anaerobic CO dehydrogenases catalyze the reversible oxidation of CO to CO2 at a complex Ni-, Fe-, and S-containing metal center called cluster C. We report crystal structures of CO dehydrogenase II from Carboxydothermus hydrogenoformans in three different states. In a reduced state, exogenous CO2 supplied in solution is bound and reductively activated by cluster C. In the intermediate structure, CO2 acts as a bridging ligand between Ni and the asymmetrically coordinated Fe, where it completes the square-planar coordination of the Ni ion. It replaces a water/hydroxo ligand bound to the Fe ion in the other two states. The structures define the mechanism of CO oxidation and CO2 reduction at the Ni-Fe site of cluster C.     

一氧化碳:植物气体信号分子的新成员

一氧化碳(carbon monoxide,CO)是植物中新发现的气体信号分子,在植物体内主要由血红素加氧酶(heme oxygenase,HO)催化产生,并应答多种激素处理和环境胁迫因子对植物的刺激。最近的研究表明,CO参与植物不定根、侧根及根毛的发育,并在植物耐受盐害、渗透、重金属、紫外辐射和营养元素缺乏等非生物胁迫中起重要的调节作用。本文综述了植物中CO的产生及其结合物、生理功能及信号作用的研究新进展,并介绍了CO与激素及其他信号分子之间的互作关系。     

纳板河流域不同植被类型下土壤肥力综合评价

研究橡胶林土壤有机碳组分及理化性状间的关系,为中国植胶区土壤质量和天然橡胶产业高效发展提供理论依据。

以海南琼中大丰农场5种林龄(2、9、12、27和31龄)橡胶林土壤样品为研究对象,用农化分析方法测定土壤理化性质和有机碳组分含量。

(1) 9龄橡胶林土壤pH最高,31龄橡胶林土壤含水量最高且容重最低,各林龄全氮、全磷和全钾含量分别低于、等于和高于全国水平。(2) 不同林龄橡胶林土壤有机碳各组分含量存在差异,其中总有机碳含量为4.58~8.52 g/kg,易氧化有机碳含量为1.72~4.66 g/kg,稳定态有机碳含量为2.05~3.27 g/kg,水溶性有机碳含量为0.23~0.48 g/kg。(3) 土壤总有机碳含量与易氧化有机碳含量、稳定态有机碳含量呈极显著正相关(P<0.01),相关系数分别为0.321和0.333。

27和31龄橡胶林因林下积累有机物较多,其土壤有机碳组分含量高于低林龄橡胶林;2龄橡胶林因刚定植,林下植被裸露,12龄橡胶林因已开割,因此,有机物流失均较多。

     

禽流感与人类健康

禽流感(avian influenza,AI)是由A型流感病毒(avian influenza virus)引起的一种禽类感染征或疾病综合症,高致病性禽流感(highly pathogenic avian influenza,HPAI)可引起禽类100％的死亡。由于抗原转变和抗原漂移,禽流感病毒是高度可变的。人禽流感是指高致病性禽流感病毒跨越物种界限,引起人类感染的一种新发传染病。目前,全球已发现H5N1、H7N7、H9N2等亚型禽流感病毒可感染人类。但目前还没有发现禽流感病毒具有在人群中相互传播的能力。对禽流感必须采用积极的预防策略。在加强监测的基础上,对家禽采用扑杀和免疫相结合的措施,可以有效地控制禽流感的流行。研制人类流感疫苗,是预防新的流感病毒株的流行的可靠保证。