The surface composition of charon: tentative identification of water ice

The 3 March 1987 Charon occultation by Pluto was observed in the infrared at 1.5, 1.7, 2.0, and 2.35 micrometers. Subtraction of fluxes measured between second and third contacts from measurements made before and after the event has yielded individual spectral signatures for each body at these wavelengths. Charon's surface appears depleted in methane relative to Pluto. Constancy of flux at 2.0 micrometers throughout the event shows that Charon is effectively black at this wavelength, which is centered on a very strong water absorption band. Thus, the measurements suggest the existence of water ice on Pluto's moon.     

保护性耕作模式下早稻田甲烷排放特征

[目的]研究耕作对早稻田甲烷排放的影响,并分析影响稻田甲烷排放的环境因子,寻找合适的耕作模式以减少稻田甲烷排放.[方法]设免耕不施肥、免耕施肥、常规不施肥和常规施肥4个处理,分别在水稻分蘖期和水稻抽穗期采用静态箱法收集气态甲烷(CH4),同步观测地温、采气箱内温度、环境温度、地表温度、草面温度、相对湿度及风速,探究早稻田CH4排放的日排放规律,明确免耕和施肥及环境因素对稻田CH4排放的影响.[结果]早稻田CH4的排放与气温、地表温度、5 cm土温、草面温度、相对湿度、风速等密切相关,尤其在分蘖期,各处理均与上述环境因子显著相关(P<0.05).不同耕作与施肥模式下,CH4日平均通量不同,在水稻分蘖期具体表现为常规施肥>常规不施肥>免耕施肥>免耕不施肥,在水稻抽穗期表现为常规不施肥>免耕施肥>常规施肥>免耕不施肥.[结论]免耕与常规耕作相比,早稻田CH4的排放量相对降低;施肥导致分蘖期早稻田CH4排放通量增加,但在抽穗期导致早稻田CH4排放减少.免耕可以减轻早稻田CH4的排放,其推广能为稻田减排做贡献.     

The nature of the near-infrared features on the venus night side

Near-infrared images of the Venus night side show bright contrast features that move from east to west, in the direction of the cloud-top atmospheric superrotation. Recently acquired images of the Venus night side along with earlier spectroscopic observations allow identification of the mechanisms that produce these features, their level of formation, and the wind velocities at those levels. The features are detectable only at wavelengths near 1.74 and 2.3 micrometers, in narrow atmospheric windows between the CO(2) and H(2)O bands. The brightest features have brightness temperatures near 480 Kelvin, whereas the darkest features are more than 50 Kelvin cooler. Several factors suggest that this radiation is emitted by hot gases at altitudes below 35 kilometers in the Venus atmosphere. The feature contrasts are produced as this thermal radiation passes through a higher, cooler, atmospheric layer that has horizontal variations in transparency. The 6.5-day east-west rotation period of the features indicates that equatorial wind speeds are near 70 meters per second in this upper layer. Similar wind speeds have been measured by entry probes and balloons at altitudes between 50 and 55 kilometers in the middle cloud layer. The bright features indicate that there are partial clearings in this cloud deck. The presence of these clearings could decrease the efficiency of the atmospheric greenhouse that maintains the high surface temperatures on Venus.     

广州地区晚季稻田甲烷排放通量与施肥影响研究

研究了广州地区晚季稻田在农业管理措施和肥效基本相同情况下，施用不同肥料类型对稻田甲烷（ＣＨ４）排放通量的影响。试验初步表明：晚季稻田ＣＨ＿４排放基本集中在水稻生长前期；稻田处于灌溉淹水状态是ＣＨ＿４产生的必要条件；稻田处于干湿期间无明显ＣＨ＿４排放；施用有机肥料ＣＨ＿４的排放量明显高于施纯化肥；温度高有利于ＣＨ＿４排放。     

The role of the tropical super greenhouse effect in heating the ocean surface

Measurements made by a Fourier transform infrared (FTIR) spectroradiometer operating in the middle infrared (5 to 20 micrometers, with a spectral resolution of one inverse centimeter) imply that there is an anomalously large greenhouse effect over equatorial oceans that is caused by water vapor. As sea-surface temperature increased from 297 to 303 degrees kelvin, the net infrared cooling at the surface decreased by 30 to 50 watts per square meter. Thus, according to the FTIR data, the super greenhouse effect that had been inferred from satellite measurements contributes directly to radiative heating of the sea surface. The data demonstrate that most of this heating occurs in the middle infrared by means of the continuum emission window of water vapor and that tropical deep convection contributes substantially to this super greenhouse effect.     

Widespread morning drizzle on Titan

Precipitation is expected in Titan's atmosphere, yet it has not been directly observed, and the geographical regions where rain occurs are unknown. Here we present near-infrared spectra from the Very Large Telescope and W. M. Keck Observatories that reveal an enhancement of opacity in Titan's troposphere on the morning side of the leading hemisphere. Retrieved extinction profiles are consistent with condensed methane in clouds at an altitude near 30 kilometers and concomitant methane drizzle below. The moisture encompasses the equatorial region over Titan's brightest continent, Xanadu. Diurnal temperature gradients that cause variations in methane relative humidity, winds, and topography may each be a contributing factor to the condensation mechanism. The clouds and precipitation are optically thin at 2.0 micrometers, and models of "subvisible" clouds suggest that the droplets are 0.1 millimeter or larger.     

Pluto: evidence for methane frost

Infrared photometry (1.2 to 2.2 micrometers) of Pluto provides evidence for frozen methane on the surface of the planet. This appears to be the first observational indication of this ice in the solar system. Its presence on Pluto suggests that the planet's albedo (reflectance) may be >/= 0.4 and that its diameter may be less than that of the moon.     

Io: an intense brightening near 5 micrometers

Spectrophotometric observations of the jovian satellite Io on 20 and 21 February 1978 (Universal Time) were made from 1.2 to 5.4 micrometers. Io's brightness at 4.7 to 5.4 micrometers was found to be three to five times greater at an orbital phase angle of 68 degrees than at orbital phase angles of 23 degrees (5.5 hours before the brightening) and 240 degrees (20 hours after the brightening). Since the 5-micrometer albedo of Io is near unity under ordinary conditions, the observed transient phenomenon must have been the result of an emission mechanism. Although several such mechanisms were examined, the actual choice is not clear.     

Submillimeter heterodyne detection of interstellar carbon monoxide at 434 micrometers

A submillimeter heterodyne radiometer, developed for astronomical applications, uses an optically pumped laser local oscillator and a quasi-optical Schottky diode mixer. The resultant telescope-mounted system, which has a noise temperature less than 4000 K (double sideband) and high frequency and spatial resolution, has been used to detect the J = 6 --> 5 rotational transition of carbon monoxide at 434 micrometers in the Orion molecular cloud. The measurements, when compared with previous millimeter-wave data, indicate that the broad carbon monoxide emission feature is produced by an optically thin gas whose temperature exceeds 180 K.     

Jupiter's Spectrum Between 12 and 24 Micrometers

Spectroscopic measurements of the thermal radiation from Jupiter between 12 and 24 micrometers (420 to 840 reciprocal centimeters) with a resolution of 4 reciprocal centimeters are used to infer the Jovian temperature structure in the pressure region 0.1 to 0.4 atmosphere. The brightness temperature spectrum is in good agreement with previous ground-based measurements between 11 and 13 micrometers and with airborne measurements between 18 and 25 micrometers. However, the integrated flux calculated for a filter window and viewing angle equivalent to those of the 20 micrometer channel of Pioneer 10 is 20 percent below that measured by the Pioneer infrared radiometer. The Q branch of the v(5) fundamental band of acetylene at 730 reciprocal centimeters appears in emission and leads to a mixing ratio estimate of 10(-6 +/- 0.5).     

稻田土壤氧化态有机碳组分变化及其与甲烷排放的关联性

稻田土壤有机碳是甲烷排放的关键底物之一,不同研究者由于采取的有机碳研究方法不同而得出稻田甲烷排放与土壤有机碳关系的结论不一。为明确影响稻田甲烷排放的土壤有机碳组分,设计了稻田施用不同外源有机碳(稻草还田、鸡粪和猪粪)的田间试验,对稻田甲烷排放和土壤有机碳组分的动态变化及其关联性进行监测和分析。结果表明,猪粪处理的甲烷排放与化肥处理无显著差异,而鸡粪和稻草2个处理的甲烷排放分别比化肥增加1.67倍(P<0.05),2.69倍(P<0.05);甲烷排放量与土壤易氧化有机碳含量显示相同顺序:稻草>鸡粪>猪粪>化肥;通径分析表明,土壤易氧化有机碳组分1(被33 mmol/L KMnO₄氧化的有机碳)与甲烷排放直接相关,其他有机碳组分仅通过组分1间接作用于水稻生育后期甲烷排放,且排放量较低。由此推断,易氧化有机碳组分1是甲烷排放的主要底物,通过有效措施降低肥源中易氧化态有机碳组分1是减排甲烷的关键技术之一。     

Spectroscopic determination of the phase composition and temperature of nitrogen ice on triton

Laboratory spectra of the first overtone band (2.1480 micrometers, 4655.4 reciprocal centimeters) of solid nitrogen show additional structure at 2.1618 micrometers (4625.8 reciprocal centimeters) over a limited temperature range. The spectrum of Neptune's satellite Triton shows the nitrogen overtone band as well as the temperature-sensitive component. The temperature dependence of this band may be used in conjunction with ground-based observations of Triton as an independent means of determining the temperature of surface deposits of nitrogen ice. The surface temperature of Triton is found to be 38.0(+2.0)(-1.0) K, in agreement with previous temperature estimates and measurements. There is no spectral evidenceforthe presence of alpha-nitrogen on Triton's surface, indicating thatthere is less than 10 percent carbon monoxide in solid solution with the nitrogen on the surface.     

地下水位与有机肥及水分管理对稻田甲烷排放的影响

采用长期定位模拟试验研究了地下水位，有机肥、水分管理对稻田甲烷排放的影响。结果表明，不同有机肥用量条件下，早委高量绿肥低水位处理稻田甲烷排放速率高于常量绿肥低水位处理，晚稻则相反；不同地下水位条件下，早稻高量绿肥低水位处理稻田甲烷排放速率高于高量绿肥高水位处理，晚稻相反；但是间歇排灌处理无论是排放速率还是排放总量都大大低于正常灌溉处理，且在所有处理中也是最低的。可见，干湿交替的水分管理方式是控制稻田甲烷排放的有效方法。     

Studies on Technique of Reducing Methane Emission in a Rice-Duck Ecological System and the Evaluation of Its Economic Significance

The rice-duck ecological system is one of the major practices of the traditional Chinese agriculture. A study on the effect of reducing methane emission using this practice provided theoretical and practical basis for further development and utilization of this classical agricultural technique. The effect of reducing methane emission and the economic benefits of rice-duck ecological system were studied by carrying out a field experiment and by using economic methodology. The daily variation of CH4 emission in late rice paddy field was basically consistent with the daily variation of atmospheric temperature. The highest emission occurred at the full tillering stage of late rice with a rate of 24.1 or 32.2 or 40.5 mg m^-2 h^-1 in no-tillage area with duck and no-tillage area without duck and conventional-tillage area without duck, respectively. The inhibition of methane emission was apparently effective in the rice-duck ecological system during the initial tillering stage and the full tillering stage. Compared to the no-tillage area without duck, methane emission decreased by 2.333 g m^-2. Compared to the conventional-tillage area without duck, methane emission decreased by 4.723 g m^-2. During the production period of late rice, the amount of methane emission in no-tillage area with duck was 3.373 g m^-2 lesser than that of no-tillage area without duck, and 5.59 g m^-2 less than that of conventional-tillage without duck area. The economic significance was analyzed. Farmers adopting the rice-duck ecological system obtained 2 166 and 4 207 RMB yuan ha^-1 more income than those who adopted a no-tillage without duck technique or conventional-tillage without duck technique, respectively. In addition to the reduction of the environmental pollution by methane emission, the farmers who adopted the rice-duck ecological system achieved economic benefits of 5 000 RMB yuan ha^-1, which was 2 206 and 4 274 RMB yuan ha^-1 more than those who adopted a no-tillage without duck technique and a conventional-tillage without duck technique, respectively. The rice-duck ecological system not only increased the economic benefits for farmers, but also reduced methane emission in rice paddy field. A sustainable agricultural production mode was formed.     

Mussel growth supported by methane as sole carbon and energy source

Symbioses between chemoautotrophic bacteria and several specialized marine invertebrates are well documented. However, none of these symbioses have been demonstrated to provide sufficient energy and carbon to the host to enable it to grow. Growth rates of seep mussels collected from hydrocarbon seeps off the coast of Louisiana were measured in a controlled environment where methane was the sole carbon and energy source. The growth rates increased to a maximum of 17.2 micrometers per day in response to methane and approached zero in the absence of methane. These mussels contain methanotrophic symbiotic bacteria in their gills, which suggests that these bacteria provide their hosts with a net carbon flux originating from methane.     

The role of ocean-atmosphere interactions in tropical cooling during the last glacial maximum

A simulation with a coupled atmosphere-ocean general circulation model configured for the Last Glacial Maximum delivered a tropical climate that is much cooler than that produced by atmosphere-only models. The main reason is a decrease in tropical sea surface temperatures, up to 6 degrees C in the western tropical Pacific, which occurs because of two processes. The trade winds induce equatorial upwelling and zonal advection of cold water that further intensify the trade winds, and an exchange of water occurs between the tropical and extratropical Pacific in which the poleward surface flow is balanced by equatorward flow of cold water in the thermocline. Simulated tropical temperature depressions are of the same magnitude as those that have been proposed from recent proxy data.     

种植杂交稻对甲烷排放及土壤产甲烷菌的影响

经早稻、中稻、晚稻三季２４ ｈ 稻田甲烷监测结果表明,种植杂交稻没有明显增进稻田甲烷排放的作用。在三季种植中,甲烷释放总量除连晚杂交稻田比常规稻高外,早稻、单季稻都是杂交稻田低于常规稻。稻田甲烷每周日平均释放量在水稻生长前期（ 移栽后５ ～７ 周） 杂交稻高于常规稻,孕穗至收获则杂交稻低于常规稻。温度对甲烷释放影响十分明显,在不同种植季,稻田甲烷释放模式不同。在三个水稻种植季中,除个别值外杂交稻田的土壤水溶甲烷含量基本都低于常规稻田。经测定,杂交稻田的土壤产甲烷细菌数量及土壤产甲烷潜力明显高于常规稻田,其中产甲烷细菌数可相差数倍乃至２ 个数量级。     

小麦冠温的多态性及其与品质变异的关联

 【目的】在对小麦冠层温度长期观测的基础上，开展了小麦冠温多态性研究，以揭示其和小麦籽粒品质变化的关联。【方法】将具有不同冠温状态的小麦材料置于不同环境条件尤其气象条件的影响之下，以引起小麦籽粒品质的变异。【结果】小麦按其冠温状态可分为3种类型：冷型小麦，其冠温年年表现为冷型态；暖型小麦，其冠温年年表现为暖型态；中间型小麦，其冠温主要表现为包括冷型态，暖型态在内的6种状态。在不同环境影响下，冷型小麦的品质变异最小，最为稳定；暖型小麦次之；中间型小麦变异最大，最不稳定。其实质在于小麦植株体内所进行的有关生理生化过程的稳定性因小麦温度型而异。【结论】鉴于冷型小麦具有品质变异小的特性，因而，降低小麦株温、培育出冷型小麦可能是解决小麦品质广幅生态适应性的有效途径。     

Viking: Mars atmospheric water vapor mapping experiment--preliminary report of results

Observations made from the Viking I orbiter show very little water vapor in the Mars atmosphere in the southern hemisphere (0 to 3 precipitable micrometers) with a gradual increase across the equator to northern latitudes. Maximum amounts between 20 and 30 micrometers have been observed in the short period covered by the observations to date. The season, northern midsummer, corresponds to the beginning of the water vapor cycle in that hemisphere. A strong repetitive diurnal cycling between the solid and vapor phases is observed at a site to the east of the Tharsis Ridge at 10 degrees north latitude; the vapor lies close to the martian surface and is most probably in saturation equilibrium with a surface haze or fog throughout much of the day.     

Characterization of Io's Volcanic Activity by Infrared Polarimetry

The thermal emission from Io's volcanic hot spots is linearly polarized. Infrared measurements at 4.76 micrometers show disk-integrated polarization as large as 1.6 percent. The degree and position angle of linear polarization vary with Io's rotation in a manner characteristic of emission from a small number of hot spots. A model incorporating three hot spots best fits the data. The largest of these hot spots lies to the northeast of Loki Patera, as mapped from Voyager, and the other spot on the trailing hemisphere is near Ra Patera. The hot spot on the leading hemisphere corresponds to no named feature on the Voyager maps. The value determined for the index of refraction of the emitting surface is a lower bound; it is similar to that of terrestrial basalts and is somewhat less than that of sulfur.