Age of Canada basin deep waters: a way to estimate primary production for the arctic ocean

An empirical model of carbon flux and (14)C-derived ages of the water in the Canada Basin of the Arctic Ocean as a function of depth was used to estimate the long-term rate of primary production within this region. An estimate can be made because the deep waters of the Canadian Basin are isolated from the world oceans by the Lomonosov Ridge (sill depth about 1500 meters). Below the sill, the age of the water correlates with increased nutrients and oxygen utilization and thus provides a way to model the average flux of organic material into the deep basin over a long time period. The (14)C ages of the deep water in the Canada Basin were about 1000 years, the carbon flux across the 1500-meter isobath was 0.3 gram of carbon per square meter per year, and the total production was 9 to 14 grams of carbon per square meter per year. Such estimates provide a baseline for understanding the role of the Arctic Ocean in global carbon cycling.     

Surface oxidation: a major sink for water on Mars

Surface oxidation irreversibly removes both oxygen and hydrogen from the martian atmosphere at a rate of 10(8) to 10(11) per square centimeter per second. This rate corresponds to a net loss of 10(25) to 10(28) per square centimeter (10(2) to 10(5) grams per square centimeter) of H(2)O, if it is assumed that the loss rate is uniform over geologic time. Heretofore, exospheric escape was considered to be the principal irreversible sink for H(2)O, but the loss rate was estimated to be only 10(8) per square centimeter per second. It is possible that surface oxidation may have had a minor effect on the supply of H(2)O in the regolith and polar caps.     

Pogonophora on the New England Continental Slope

Two species of Pogonophora on the continental slope off southern New England are reported. Two species were found: Siboglinum ekmani J?gersten and Siboglinum sp., an undescribed species. The density of both species combined, at 366 mmicro, was 30 per square meter and at 567 m depth, it was 25 per square meter. The dominant macrobenthic organisms with which they were associated were polychaete worms and foraminiferans.     

Chemosynthetic mussels at a brine-filled pockmark in the northern gulf of Mexico

A large (540 square meters) bed of Bathymodiolus n. sp. (Mytilidae: Bivalvia) rings a pool of hypersaline (121.35 practical salinity units) brine at a water depth of 650 meters on the continental slope south of Louisiana. The anoxic brine (dissolved oxygen 相似文献   

Petroleum lumps on the surface of the sea

Lumps of crude oil residue floating the sea surface have been observed widely. Samples were taken with surface-skimming nets in the Mediter-ranean Sea and eastern North Atlantic Ocean; their displacement volumes were as large as 0.5 milliliter per square meter. An isopod, Idotea metallica, appears to be associated with the lumps, and a barnacle, Lepas pectinata, grows upon them. Lumps were found in stomachs of Scomberesox saurus, a surface-feeding fish importanit in ocean food webs. Films on the lumps, presumably consisting mostly of bacteria, consumed oxygen at the rate of 4 cubic millimeters per hour per square centimeter of lump surface. Chemical analysis suggested that certain lumps had been at large for only a few weeks; data from barnacle size and growth rate suggested that other lumps were at least 2 months old.     

珠江三角洲冲积平原土壤镉高含量区形成原因

通过现场采样及室内分析方法,研究了珠江三角洲冲积平原土壤Cd高含量区形成的原因。调查发现,在西江和北江冲积平原存在Cd的高含量分布区。Cd高含量区仅分布于第四纪海陆交互相,从地表至深部含量变化不大,为珠江三角洲形成过程中,富含Cd的西江和北江冲积物质在珠江三角洲沉积而成。Cd高含量区空间分布特征明显,控制因素显著,属于由地质作用引起。这一结论与多数研究者认为是人为因素引起的具有根本差别。     

Escape of hydrogen from venus

Recombination of O(2)(+) represents a source of fast oxygen atoms in Venus' exosphere, and subsequent collisions of oxygen atoms with hydrogen atoms lead to escape of about 10(7) hydrogen atoms per square centimeter per second. Escape of deuterium atoms is negligible, and the ratio of deuterium to hydrogen should increase with time. It is suggested that the mass-2 ion observed by Pioneer Venus is D(+), which implies a ratio of deuterium to hydrogen in the contemporary atmosphere of about 10(-2), an initial ratio of 5 x 10(-5) and an original H(2)O abundance not less than 800 grams per square centimeter.     

Solar particle tracks in glass from the surveyor 3 spacecraft

A glass filter from Surveyor 3 has a surface density of approximately 1 x 10(6) tracks per square centimeter from heavy solar flare particles. The variation with depth is best fitted with a solar particle spectrum dN/dE = 2.42 x 10(6) E(-2) [in particles per square centimeter per year per steradian per (million electron volts per nucleon)], where E is the energy and N is the number of particles, from 2 million electron volts per nucleon to approximately 7 million electron volts per nucleon and dN/dE = 1.17 x 10(7) E(-3) at higher energies. Not much difference is observed between 0.5 and 5 micrometers, an indication that there is a lack of track-registering particles below 0.5 million electron volts per nucleon. The Surveyor data are compatible with track results in lunar rocks, provided an erosion rate of approximately 10(-7) centimeter per year is assumed for the latter. The results also suggest a small-scale erosion process in lunar rocks.     

黔南植烟土壤杂草种子库初步研究

采用单因素随机区组设计,通过种子萌发试验,对贵州省黔南长顺、贵定烟区烟田土壤杂草种子库的组成、数量及杂草种子萌发的规律进行了研究。结果表明,该区土壤杂草种子库共有杂草种类13科18种,主要分布在0~10 cm土层,约为该区土壤杂草生长总量的54.41%。杂草种类主要有禾本科看麦娘(Alopecurus aequalis Sohcl)、金色狗尾草(Setaria gleuca(linn.)beauv),占该区烟田土壤杂草数量的70.48%,是该区杂草防治的重点;其中,长顺烟田土壤杂草种子较多,0~30 cm土层的杂草种子密度为24 180粒/m2,贵定烟田相对较少,为14 660粒/m2。     

Kinetics of single-layer graphite oxidation: evaluation by electron microscopy

Etch-decoration reveals that the rate of removal of carbon atoms exposed at monolayer steps on graphite surfaces is very different from the rate of removal, under identical conditions, at multilayer steps. At 1113 degrees K and a pressure of 1.33 newtons per square meter of oxygen, the rate of oxidation (along the layer planes) is less by a factor of nearly 100 than that at multilayer steps.     

Radium-226 and radon-222: concentration in atlantic and pacific oceans

Measurements of radon-222 in seawater suggest the following. The radium-226 content of surface water in both the Atlantic and Pacific oceans is uniformly close to about 4 x 10(-14) gram per liter. The deep Pacific has a concentration of radium-226 that is four times higher and the deep Atlantic a concentration twice as high as that of the surface. These distribution profiles can be explained by the same particle-settling rate for radium-226 from surface to depth for the two oceans and by a threefold longer residence time of water in the deep Pacific than in the deep Atlantic. The vertical distribution of the deficiency of radon-222 in the surface water of the northwest Pacific Ocean suggests a coefficient of vertical eddy diffusion as high as 120 square centimeters per second and a gas-exchange rate for carbon dioxide in surface water between 14 and 60 moles per square meter per year. Vertical profiles of the excess of radon-222 in near-bottom water of the South Atlantic give coefficients of vertical eddy diffusion ranging from 1.5 to more than 50 square centimeters per second.     

Lunar Surface Strength Estimate from Orbiter II Photograph

Lunar Orbiter II photographed a 13-meter boulder which has rolled down the inner slope of a 3-kilometer crater leaving a track 6 meters wide. A static-bearing . strength of 4 x 10(6) dynes per square centimeter at 75-centimeter depth is estimated from these data if certain assumptions are made.     

Measurement of the effect of Amazon smoke on inhibition of cloud formation

Urban air pollution and smoke from fires have been modeled to reduce cloud formation by absorbing sunlight, thereby cooling the surface and heating the atmosphere. Satellite data over the Amazon region during the biomass burning season showed that scattered cumulus cloud cover was reduced from 38%in clean conditions to 0%for heavy smoke (optical depth of 1.3). This response to the smoke radiative effect reverses the regional smoke instantaneous forcing of climate from -28 watts per square meter in cloud-free conditions to +8 watts per square meter once the reduction of cloud cover is accounted for.     

杂交棉种植密度与留叶枝对产量及其构成因素的互作效应研究

以杂交棉鲁棉研25号为试验材料,采用裂区设计,于2008年在山东临清、嘉祥和金乡三地大田条件下研究了种植密度与留叶枝对产量及其构成因素等的互作效应。结果表明：密度和整枝对杂交棉产量、产量构成以及熟相有显著的互作效应。去叶枝情况下,低密度（3.00株/m2）和高密度（7.50株/m2）处理的产量低,中高密度（4.50-6.00株/m2）的产量较高;留叶枝条件下,低密度（3.00株/m2）产量最高,中高密度（4.50-6.00株/m2）的产量居中,而高密度（7.50株/m2）处理的产量还是最低;整枝条件下4.50株/m2密度处理的籽棉和皮棉产量比3.00株/m2分别增产4.93%和5.51%,而留叶枝条件下3.00株/m2的籽棉产量比4.50株/m2高4.03%。低密度（3.00株/m2）下留叶枝的铃数多于去叶枝的铃数,但随密度增加（4.50株/m2及以上）,留叶枝的铃数显著少于去叶枝的铃数;留叶枝和增加密度都会降低铃重。密度与整枝对棉柴比没有显著的互作效应,但都可显著影响生物产量。密度与整枝对棉花早熟性也有互作效应,去叶枝的早熟性好于留叶枝的处理,随密度增加,早熟性降低。     

鳢肠马唐竞争作用研究

采用人工接草的方法 ,研究了鳢肠 (EcliptaprostrataL .)和马唐 (DigitaiaSan guinalisL .Scop .)的竞争作用。结果表明 :在数量上 ,当鳢肠、马唐的接草密度分别为 4 0株·m- 2 和 30 0 0茎蘖·m- 2 ,草龄为 64d ,马唐的密度达 2 0 0 0株·m- 2 时 ,鳢肠灭绝 ;而当鳢肠、马唐的接草密度分别为 1 40 0株·m- 2 、 8 4株·m- 2 、草龄为 5 4d ,鳢肠的密度达 1 2 0 0株·m- 2时 ,马唐灭绝。从单位面积生物量上看 :当鳢肠、马唐接草密度、草龄及马唐单位面积生物量分别为 1 0株·m- 2 、 2 1 0 0株·m- 2 、 72d和 70 95 7g·m- 2 时 ,鳢肠灭绝 ;而当它们的接草密度、草龄及鳢肠单位面积生物量分别为 1 40 0株·m- 2 、 1 0株·m- 2 、 72d和 1 2 65 3g·m- 2 时 ,马唐灭绝。并组建了马唐、鳢肠单位面积生物量、数量、单株生物量竞争模型     

Local influences on shear-flow turbulence in the equatorial ocean

A 12-day series of 1749 profiles of turbulent kinetic energy dissipation above the equatorial undercurrent at 140 degrees west showed that, in the upper 110 meters of the ocean, the dissipation radically decreased during the solar heating period each day. Daily averages were linearly related to the local wind power. When integrated over the depth range of 10 to 110 meters, the dissipation was 10.6 ergs per square centimeter per second or 0.92 +/- 0.10 percent of the wind power, a proportion not substantially different from those found in mid-latitude surface mixed layers. These results suggest that much of the energy dissipated above the equatorial undercurrent may be extracted directly from the local wind.     

雷竹地下鞭的系统结构

对雷竹地下鞭进行调查研究的结果表明:①雷竹地下鞭鞭段数为5.6条/m2,鞭长为9.6m/m2,体积为4.710-4m3/m2。在土中分布可深达60cm,11～40cm之间占80.0%以上,其中2～4龄鞭占总鞭数的85.0%。②壮芽占总芽数的31.1%,集中着生在3～4龄鞭上,发笋能力以3～4龄最强,占当年发笋总数的70.0%～80.0%;③壮芽和发笋位置在鞭段中部最多,6～15节壮芽占58.7%,发笋占70.1%,岔鞭多发生在鞭段前梢,在1～6节占67.0%;④鞭的延伸方向以平行林地和向上生长的类型为多,约占80.0%以上,向上坡伸展的在50.0%左右,向下坡伸展甚少;⑤以土壤肥沃深厚、疏松通气、蓄水保肥性能良好的竹林地鞭量较多,分布结构合理;⑥立竹1000～1100株/1000m2的竹林,地下鞭结构最适宜;随着发育年龄的增大（12年生以上）,壮龄鞭和壮芽渐减,老鞭增多。     

山东生态条件下纯作春棉的适宜密度研究

以常规抗虫棉鲁棉研28号为材料,在山东广饶、夏津和冠县三地大田条件下纯作种植,研究了不同密度（3.00～9.00株/m2）下的棉花产量及产量构成。结果表明,种植密度对纯作抗虫棉产量、产量构成以及熟相均有显著的影响,对经济产量的调控效应三个试验点大致相同,都随密度的增加呈现先升后降的趋势。即低密度（3.00株/m2）和高密度（9.00株/m2）处理的产量低,中高密度（4.50～7.50株/m2）的产量较高。三个点平均,6.00株/m2密度处理的籽棉和皮棉产量与4.50株/m2处理相当,但比3.00株/m2分别增产10.1%和12.0%,比9.00株/m2处理分别增产22.3%和22.8%。提高密度能提高单位面积的生物产量和单位面积铃数,但可显著降低棉柴比、铃重和早熟性。密度偏高和偏低都不能获得较高的经济产量和协调的产量结构,山东春棉纯作条件下适宜种植密度为4.50～6.00株/m2。     

The Discovery of America: The first Americans may have swept the Western Hemisphere and decimated its fauna within 1000 years

I propose a new scenario for the discovery of America. By analogy with other successful animal invasions, one may assume that the discovery of the New World triggered a human population explosion. The invading hunters attained their highest population density along a front that swept from Canada to the Gulf of Mexico in 350 years, and on to the tip of South America in roughly 1000 years. A sharp drop in human population soon followed as major prey animals declined to extinction. Possible values for the model include an average frontal depth of 160 kilometers, an average population density of 0.4 person per square kilometer on the front and of 0.04 person per square kilometer behind the front, and an average rate of frontal advance of 16 kilometers per year. For the first two centuries the maximum rate of growth may have equaled the historic maximum of 3.4 percent annually. During the episode of faunal extinctions, the population of North America need not have exceeded 600,000 people at any one time. The model generates a population sufficiently large to overkill a biomass of Pleistocene large animals averaging 9 metric tons per square kilometer (50 animal units per section) or 2.3 x 10(8) metric tons in the hemisphere. It requires that on the front one person in four destroy one animal unit (450 kilograms) per week, or 26 percent of the biomass of an average section in 1 year in any one region. Extinction would occur within a decade. There was insufficient time for the fauna to learn defensive behaviors, or for more than a few kill sites to be buried and preserved for the archeologist. Should the model survive future findings, it will mean that the extinction chronology of the Pleistocene megafauna can be used to map the spread of Homo sapiens throughout the New World.     

群体配置对大豆品种黑农51产量和相关性状发育作用的初步分析

通过对正方形和传统垄作栽培模式下不同群体密度的产量表现及相关的产量性状进行研究,结果初步表明,正方形最佳田间密度为15.32株·m^-2,最高理论产量为2585.70 kg·hm^-2;垄上双行栽培最佳密度为19.9株·m^-2,最高理论产量为3159.35 kg·hm^-2;垄上双行最高产量高于正方形栽培;单株产量的有效株行距为62.43 cm×62.43cm,与传统垄作垄距65～70cm是接近的,说明对于繁茂型晚熟大豆品种而言,传统的65～70cm垄作模式仍然不失为一种实用有效的栽培技术模式。7月中旬以后旱情导致LAI在R4期下降;在R4和R6期,25.0～44.4株·m^-2不同密度间的LAI,传统垄作高于正方形模式;在分枝期（V6）干物质积累量最低,同期根冠比相对最高,表明前期是根系发育优先期;在R6期从5.9～36.6株·m^-2密度范围内,传统垄作栽培模式单株干物质积累值显著高于正方形栽培模式;与平作为特点的正方形栽培相比,传统垄作模式有利于根系发育。