Record of Volcanism Since 7000 B.C. from the GISP2 Greenland Ice Core and Implications for the Volcano-Climate System

Sulfate concentrations from continuous biyearly sampling of the GISP2 Greenland ice core provide a record of potential climate-forcing volcanism since 7000 B.C. Although 85 percent of the events recorded over the last 2000 years were matched to documented volcanic eruptions, only about 30 percent of the events from 1 to 7000 B.C. were matched to such events. Several historic eruptions may have been greater sulfur producers than previously thought. There are three times as many events from 5000 to 7000 B.C. as over the last two millennia with sulfate deposition equal to or up to five times that of the largest known historical eruptions. This increased volcanism in the early Holocene may have contributed to climatic cooling.     

Burst Conditions of Explosive Volcanic Eruptions Recorded on Microbarographs

Explosive volcanic eruptions generate pressure disturbances in the atmosphere that propagate away either as acoustic or as shock waves, depending on the explosivity of the eruption. Both types of waves are recorded on microbarographs as 1- to 0.1-hertz N-shaped signals followed by a longer period coda. These waveforms can be used to estimate burst pressures and gas concentrations in explosive volcanic eruptions and provide estimates of eruption magnitudes.     

A 1500-year record of tropical precipitation in ice cores from the quelccaya ice cap, peru

Two ice cores, covering 1500 years of climatic information, from the summit (5670 meters) of the tropical Quelccaya ice cap, in the Andes of southern Peru, provide information on general environmental conditions including droughts, volcanic activity, moisture sources, temperature, and glacier net balance. The net balance record reconstructed from these cores reflects major precipitation trends for the southern Andes of Peru. These records indicate extended dry periods between 1720 and 1860, 1250 and 1310, and 570 and 610; wet conditions prevailed between 1500 and 1720. Establishing a tropical precipitation record may help explain climatic fluctuations since the tropical evaporation-precipitation cycle is a principal mechanism driving the atmospheric circulation.     

Carbonyl sulfide and carbon disulfide from the eruptions of mount st. Helens

Ash from the massive 18 May 1980 eruption of Mount St. Helens readily gave off large amounts of carbonyl sulfide and carbon disulfide gases at room temperature. These findings suggest that the sulfur that enhances the Junge sulfate layer in the stratosphere after volcanic eruptions could be carried directly to the upper atmosphere as carbonyl sulfide and carbon disulfide adsorbed on ash particles from major volcanic eruptions.     

European seasonal and annual temperature variability, trends, and extremes since 1500

Multiproxy reconstructions of monthly and seasonal surface temperature fields for Europe back to 1500 show that the late 20th- and early 21st-century European climate is very likely (>95% confidence level) warmer than that of any time during the past 500 years. This agrees with findings for the entire Northern Hemisphere. European winter average temperatures during the period 1500 to 1900 were reduced by approximately 0.5 degrees C (0.25 degrees C for annual mean temperatures) compared to the 20th century. Summer temperatures did not experience systematic century-scale cooling relative to present conditions. The coldest European winter was 1708/1709; 2003 was by far the hottest summer.     

Holocene eruptive activity of el chichon volcano, chiapas, Mexico

Geologic and radiometric-age data indicate that El Chichón was frequently and violently active during the Holocene, including eruptive episodes about 600, 1250, and 1700 years ago and several undated, older eruptions. These episodes, involving explosive eruptions of sulfur-rich magma and associated dome-growth processes, were apparently separated by intervals of approximately 350 to 650 years. Some of El Chichón's eruptions may correlate with unusual atmospheric phenomena around A.D. 1300 and possibly A.D. 623.     

Monitoring the 1980-1982 eruptions of mount st. Helens: compositions and abundances of glass

The Mount St. Helens eruptive sequence of 1980 through 1982 reflects the tapping of successively less water-rich, more highly crystallized, and more viscous, highly phyric dacitic magmas. These changes reflect both syn- and preeruption processes. The decreasing water content points to a continued decline in the volume and intensity of explosive pyroclastic activity. This decreasing water content appears to be composed of a long-term trend established during a long period of repose (about 130 years) imposed on short-term trends established during short periods (about 7 to 100 days) of repose between eruptions in the present eruptive cycle. The last two eruptive cycles of this volcano, the T (A.D. 1800) and W cycles (about A. D. 1500), exhibited similar trends. These changes are inferred from a combination of petrographic, bulk chemical, and electron- and ion-microprobe analyses of matrix and melt-inclusion glasses.     

Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period

A precise relative chronology for Greenland and West Antarctic paleotemperature is extended to 90,000 years ago, based on correlation of atmospheric methane records from the Greenland Ice Sheet Project 2 and Byrd ice cores. Over this period, the onset of seven major millennial-scale warmings in Antarctica preceded the onset of Greenland warmings by 1500 to 3000 years. In general, Antarctic temperatures increased gradually while Greenland temperatures were decreasing or constant, and the termination of Antarctic warming was apparently coincident with the onset of rapid warming in Greenland. This pattern provides further evidence for the operation of a "bipolar see-saw" in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales.     

Greenland ice evidence of hemispheric lead pollution two millennia ago by greek and roman civilizations

Analysis of the Greenland ice core covering the period from 3000 to 500 years ago-the Greek, Roman, Medieval and Renaissance times-shows that lead is present at concentrations four times as great as natural values from about 2500 to 1700 years ago (500 B.C. to 300 A.D.). These results show that Greek and Roman lead and silver mining and smelting activities polluted the middle troposphere of the Northern Hemisphere on a hemispheric scale two millennia ago, long before the Industrial Revolution. Cumulative lead fallout to the Greenland Ice Sheet during these eight centuries was as high as 15 percent of that caused by the massive use of lead alkyl additives in gasoline since the 1930s. Pronounced lead pollution is also observed during Medieval and Renaissance times.     

Sighting of el chichon sulfur dioxide clouds with the nimbus 7 total ozone mapping spectrometer

The eruptions of El Chichón volcano on 28 March and 3 and 4 April 1982 were observed by the Nimbus 7 total ozone mapping spectrometer due to strong absorption by volcanic gases at the shortest wavelengths of the spectrometer (312.5 and 317.5 nanometers). These ultraviolet pictures permit a measurement of the volume, dispersion, and drift of volcanic gas clouds. The tropospheric clouds were rapidly dispersed in westerly winds while persistent stratospheric clouds drifted in easterly winds at speeds up to 13 meters per second. The spectral reflectance is consistent with sulfur dioxide absorption and rules out carbon disulfide as a major constituent. A preliminary estimate of the mass of sulfur dioxide deposited in the stratosphere by the large eruptions on 3 and 4 April is 3.3 x 10(6) tons. Prior estimates of volcanic cloud volume were based on extrapolation of locally measured sulfur dioxide concentrations.     

Can rapid climatic change cause volcanic eruptions?

Many major volcanic eruptions coincide with cooling trends of decadal or longer duration that began significantly before the eruptions. Dust veils provide positive feedback for short-term (less than 10 year) global cooling, but seem unlikely to trigger glaciations or even minor climate fluctuations in the 10-to 100-year range. On the contrary, variations in climate lead to stress changes on the earth's crust-for instance, by loading and unloading of ice and water masses and by axial and spin-rate changes that might augment volcanic (and seismic) potential.     

Electrical origin of the outbursts on io

The outbursts seen on Jupiter's satellite Io have been described as volcanic eruptions. They may instead be the result of large electric currents flowing through hot spots on Io and causing evaporation of surface materials. A strictly periodic behavior would then be expected.     

Electron-microprobe analyses of phases in lunar samples

In fine (type A) and coarse-grained (type B) Apollo 11 lunar volcanic rocks clinopyroxenes are extremely inhomogeneous. Ferrosilite-rich areas in type B rocks have decomposed to submicron vermicular intergrowths of clinopyroxene-fayalite-cristobalite(?). Plagioclase has normal zoning with K(2)O up to 0.5 percent in rims. Ilmenites are relatively homogeneous with low mgo(0.1 to 2 percent) and high zro(2) (up to 0.26 percent). Metal phase in troilite has <0.02 percent nickel. The breccias (type C) and fines (type D) containing 0.09 to 10.52 percent Ti0(2.) Rare metal fragments with meteorite-like compositions occur in breccias and fines. Gross similarities between euctites and Apollo 11 volcanic rocks indiacate similar evolutionary environments, but detailed mineralogical differences suggest either separate origins or if eucrites are lunar, chemical inhomogeneities on the lunar surface.     

Biological Invasion by Myrica faya Alters Ecosystem Development in Hawaii

The exotic nitrogen-fixing tree Myrica faya invades young volcanic sites where the growth of native plants is limited by a lack of nitrogen. Myrica quadruples the amount of nitrogen entering certain sites and increases the overall biological availability of nitrogen, thereby altering the nature of ecosystem development after volcanic eruptions.     

Recent volcanism and the stratosphere

In the quiet years after the 1956 eruption of the Bezymianny volcano in central Kamchatka, it is doubtful that any volcano vented into the stratosphere until the 1963 eruptions of Agung (Bali), Trident (Alaska), and Surtsey (Iceland). From 1963 to the Hekla (Iceland) event in May 1970, two latitudinal belts of volcanoes have ejected ash and gases into the stratosphere. One belt is equatorial and the other is just below the Arctic Circle. The latter, where the tropopause is considerably lower, may have been the principal source of replenishment of volcanic dust and gases to the stratosphere. Submarine and phreatic volcanic eruptions may have been the sources of reported increase of water vapor in the stratosphere.     

Recent volcanic activity at glacier peak

Previous reports suggested that Glacier Peak, a volcano in northern Washington State, has been dormant for the past 11,000 years. New radiocarbon dates for volcanic deposits indicate that major volcanic events, such as tephra eruptions, pyroclastic flows, and mudflows traveling tens of kilometers, occurred at least five times in the past 1800 years and nine times in the past 5500 years.     

Linking petrology and seismology at an active volcano

Many active volcanoes exhibit changes in seismicity, ground deformation, and gas emissions, which in some instances arise from magma movement in the crust before eruption. An enduring challenge in volcano monitoring is interpreting signs of unrest in terms of the causal subterranean magmatic processes. We examined over 300 zoned orthopyroxene crystals from the 1980-1986 eruption of Mount St. Helens that record pulsatory intrusions of new magma and volatiles into an existing larger reservoir before the eruption occurred. Diffusion chronometry applied to orthopyroxene crystal rims shows that episodes of magma intrusion correlate temporally with recorded seismicity, providing evidence that some seismic events are related to magma intrusion. These time scales are commensurate with monitoring signals at restless volcanoes, thus improving our ability to forecast volcanic eruptions by using petrology.     

Venus: volcanic eruptions may cause atmospheric obscuration

High rates of volcanic and tectonic activities are inferred from Venus's high surface temperature. The effects of volcanic effluents, gas and dust, on obscuration in the atmosphere are considered. The optical extinction due to particulate matter is estimated from assumed distributions as to particle size and altitude. As few as ten explosive eruptions per annum would cause significant absorption and scattering of visible light.     

The Miller volcanic spark discharge experiment

Miller's 1950s experiments used, besides the apparatus known in textbooks, one that generated a hot water mist in the spark flask, simulating a water vapor-rich volcanic eruption. We found the original extracts of this experiment in Miller's material and reanalyzed them. The volcanic apparatus produced a wider variety of amino acids than the classic one. Release of reduced gases in volcanic eruptions accompanied by lightning could have been common on the early Earth. Prebiotic compounds synthesized in these environments could have locally accumulated, where they could have undergone further processing.     

4种教槽料对断奶仔猪生长性能、腹泻率和皮毛指数的影响

试验选取160头体重相近的健康断奶仔猪,随机分4个处理,每个处理4个重复,每个重复10头。分别饲喂A料、B料、C料和D料,研究4种教槽料对断奶仔猪生长性能、腹泻率和皮毛指数的影响。其中A料和D料为粉料且含有血浆蛋白粉;B料和C料配方相同,均无血浆蛋白粉,只存在B料为粉料、C料为颗粒料的区别。结果表明：断奶后10d内A料组仔猪采食量和日增重均显著高于B料和C料组（P〈0.05）,与D料组差异不显著（P〉0.05）;B料和C料组采食量、日增重均差异显著（P〈0.05）。A料组仔猪料肉比与B料和c料组差异均显著（P〈0.05）,与D料相比,其料肉比降低4.76％。对于腹泻率和腹泻指数,A料和D料间差异不显著（P〉0.05）,但在B料和C料组间差异显著（P〈0.05）。除C料组皮毛指数与各组存在显著差异外（P〈0.05）,各组间均差异不显著（P〉0.05）。以上结果表明,粉料A和D生产效果相当,但均显著好于B料、C料。