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1.
Pronounced increases in total gaseous mercury (TGM) in the near surface marine atmosphere were found in the equatorial region (4 degrees N to 10 degrees S) of the Pacific Ocean at 160 degrees W. The atmospheric enhancement of TGM corresponded closely to sea-surface manifestations of equatorial upwelling as reflected in measured changes of temperature and nutrient concentrations as well as to variations of reactive mercury in surface seawater. The elevated atmospheric TGM levels most probably result from oceanic mercury evasion associated with upwelling and increased biological production that occurs in the equatorial Pacific Ocean.This evidence of sea-to-air mercury transfer supports model predictions of an oceanic source of atmospheric mercury and suggests that marine-derived mercury emissions should occur in other biologically productive regimes. 相似文献
2.
Nitrite photolysis at natural light intensities and normal nitrite concentrations in seawater produced detectable concentrations of nitric oxide, which was consumed rapidly by a dark chemical reaction in the laboratory. Nitric oxide was also detected in situ in nitrite-rich surface waters of the central equatorial Pacific, where it formed in daylight and disappeared rapidly at sunset. The formation and rapid cycling of nitric oxide implies the presence of other free radicals in seawater, perhaps as intermediates in ongoing autoxidation processes. The central equatorial Pacific is a nitric oxide source to the atmosphere. 相似文献
3.
Biological and chemical response of the equatorial pacific ocean to the 1997-98 El Nino 总被引：1，自引：0，他引：1
Chavez FP Strutton PG Friederich GE Feely RA Feldman GC Foley DG McPhaden MJ 《Science (New York, N.Y.)》1999,286(5447):2126-2131
4.
The equatorial Pacific Ocean is one of the most important yet highly variable oceanic source areas for atmospheric carbon dioxide (CO2). Here, we used the partial pressure of CO2 (PCO2), measured in surface waters from 1979 through early 2001, to examine the effect on the equatorial Pacific CO2 chemistry of the Pacific Decadal Oscillation phase shift, which occurred around 1988 to 1992. During the decade before the shift, the surface water PCO2 (corrected for temperature changes and atmospheric CO2 uptake) in the central and western equatorial Pacific decreased at a mean rate of about -20 microatm per decade, whereas after the shift, it increased at about +15 microatm per decade. These changes altered the CO2 sink and source flux of the equatorial Pacific significantly. 相似文献
5.
Namias J 《Science (New York, N.Y.)》1973,181(4106):1244-1245
The strength of the equatorial countercurrent of the North Pacific and associated variations in sea surface temperatures at its eastern extremity off Central America are related to the zonal wind flow in the remote subtropical atmosphere with lags of as much as 8 months between wind and temperature. 相似文献
6.
Broecker W Barker S Clark E Hajdas I Bonani G Stott L 《Science (New York, N.Y.)》2004,306(5699):1169-1172
Measurements of the age difference between coexisting benthic and planktic foraminifera from western equatorial Pacific deep-sea cores suggest that during peak glacial time the radiocarbon age of water at 2-kilometers depth was no greater than that of today. These results make unlikely suggestions that a slowdown in deep-ocean ventilation was responsible for a sizable fraction of the increase of the ratio of carbon-14 (14C) to carbon in the atmosphere and surface ocean during glacial time. Comparison of 14C ages for coexisting wood and planktic foraminifera from the same site suggests that the atmosphere to surface ocean 14C to C ratio difference was not substantially different from today's. 相似文献
7.
A tropical Pacific climate state resembling that of a permanent El Ni?o is hypothesized to have ended as a result of a reorganization of the ocean heat budget approximately 3 million years ago, a time when large ice sheets appeared in the high latitudes of the Northern Hemisphere. We report a high-resolution alkenone reconstruction of conditions in the heart of the eastern equatorial Pacific (EEP) cold tongue that reflects the combined influences of changes in the equatorial thermocline, the properties of the thermocline's source waters, atmospheric greenhouse gas content, and orbital variations on sea surface temperature (SST) and biological productivity over the past 5 million years. Our data indicate that the intensification of Northern Hemisphere glaciation approximately 3 million years ago did not interrupt an almost monotonic cooling of the EEP during the Plio-Pleistocene. SST and productivity in the eastern tropical Pacific varied in phase with global ice volume changes at a dominant 41,000-year (obliquity) frequency throughout this time. Changes in the Southern Hemisphere most likely modulated most of the changes observed. 相似文献
8.
R S Foote 《Science (New York, N.Y.)》1972,177(48):513-514
The concentrations of elemental gaseous mercury in several homes, offices, and laboratories in the Dallas area have been measured. The values are substantially higher than the ambient natural background concentration, about 3 nanograms of mercury per cubic meter of air in San Francisco, Dallas, and Washington, D.C. 相似文献
9.
The equatorial Pacific is the largest oceanic source of carbon dioxide to the atmosphere and has been proposed to be a major site of organic carbon export to the deep sea. Study of the chemistry and biology of this area from 170 degrees to 95 degrees W suggests that variability of remote winds in the western Pacific and tropical instability waves are the major factors controlling chemical and biological variability. The reason is that most of the biological production is based on recycled nutrients; only a few of the nutrients transported to the surface by upwelling are taken up by photosynthesis. Biological cycling within the euphotic zone is efficient, and the export of carbon fixed by photosynthesis is small. The fluxes of carbon dioxide to the atmosphere and particulate organic carbon to the deep sea were about 0.3 gigatons per year, and the production of dissolved organic carbon was about three times as large. The data establish El Ni?o events as the main source of interannual variability. 相似文献
10.
The oceans play a major role in defining atmospheric carbon dioxide (CO2) levels, and although the geographical distribution of CO2 uptake and release in the modern ocean is understood, little is known about past distributions. Boron isotope studies of planktonic foraminifera from the western equatorial Pacific show that this area was a strong source of CO2 to the atmosphere between approximately 13,800 and 15,600 years ago. This observation is most compatible with increased frequency of La Ni?a conditions during this interval. Hence, increased upwelling in the eastern equatorial Pacific may have played an important role in the rise in atmospheric CO2 during the last deglaciation. 相似文献
11.
Twentieth-Century Sea Surface Temperature Trends 总被引：4，自引：0，他引：4
MA Cane AC Clement A Kaplan Y Kushnir D Pozdnyakov R Seager SE Zebiak R Murtugudde 《Science (New York, N.Y.)》1997,275(5302):957-960
An analysis of historical sea surface temperatures provides evidence for global warming since 1900, in line with land-based analyses of global temperature trends, and also shows that over the same period, the eastern equatorial Pacific cooled and the zonal sea surface temperature gradient strengthened. Recent theoretical studies have predicted such a pattern as a response of the coupled ocean-atmosphere system to an exogenous heating of the tropical atmosphere. This pattern, however, is not reproduced by the complex ocean-atmosphere circulation models currently used to simulate the climatic response to increased greenhouse gases. Its presence is likely to lessen the mean 20th-century global temperature change in model simulations. 相似文献
12.
Marchitto TM Lehman SJ Ortiz JD Flückiger J van Geen A 《Science (New York, N.Y.)》2007,316(5830):1456-1459
We reconstructed the radiocarbon activity of intermediate waters in the eastern North Pacific over the past 38,000 years. Radiocarbon activity paralleled that of the atmosphere, except during deglaciation, when intermediate-water values fell by more than 300 per mil. Such a large decrease requires a deglacial injection of very old waters from a deep-ocean carbon reservoir that was previously well isolated from the atmosphere. The timing of intermediate-water radiocarbon depletion closely matches that of atmospheric carbon dioxide rise and effectively traces the redistribution of carbon from the deep ocean to the atmosphere during deglaciation. 相似文献
13.
利用常规气象观测资料和国家气候中心的赤道中东太平洋海表温度、850 hPa纬向风距平和副热带高压脊线的数据,使用天气学分析方法,对2010年8月葫芦岛地区高频次暴雨的气候背景及环流形势进行分析。结果表明:2010年7月以来,赤道中东太平洋海表温度较常年同期偏低1.5～2.5℃,快速进入拉尼娜状态;热带地区低层850 hPa赤道中太平洋出现纬向风的强的负趋势,Walker环流有明显增强的正趋势;副高明显偏强,利于西太平洋暖湿的气流沿副高边缘向我国东北地区输送;3次暴雨过程均具有完整的高低空配置,低层辐合、高层辐散,水汽充沛,具有对流不稳定层结。 相似文献
14.
The role of El Ni?o-Southern Oscillation (ENSO) in greenhouse warming and climate change remains controversial. During the warmth of the early-mid Pliocene, we find evidence for enhanced thermocline tilt and cold upwelling in the equatorial Pacific, consistent with the prevalence of a La Ni?a-like state, rather than the proposed persistent warm El Ni?o-like conditions. Our Pliocene paleothermometer supports the idea of a dynamic "ocean thermostat" in which heating of the tropical Pacific leads to a cooling of the east equatorial Pacific and a La Ni?a-like state, analogous to observations of a transient increasing east-west sea surface temperature gradient in the 20th-century tropical Pacific. 相似文献
15.
Chemistry of oceanic particulate matter and sediments: implications for bottom sediment resuspension
Analyses of suspended particulate matter from the eastern equatorial Pacific Ocean have defined a 400-meter-thick benthic nepheloid layer enriched in aluminum, silicon, iron, and manganese relative to the overlying waters. Chemical mass-balance calculations suggest that the concentration increases in the benthic nepheloid layer are due to resuspension from the fraction of the local bottom sediments in the size range >/=1 micrometer. 相似文献
16.
The origin of a series of regionally correlatable seismic horizons in the Neogene sediments of the central equatorial Pacific is examined through seismic modeling and the detailed analyses of stratigraphic and physical property relationships in Deep Sea Drilling Project cores. These regionally traceable reflectors are synchronous; the younger reflectors are the direct result of carbonate dissolution events, the older ones of stratigraphically selective diagenetic processes. The changes in ocean chemistry associated with these events appear to be linked to global reorganizations of surface and bottom-water circulation patterns, the most dramatic of which are associated with reorganizations of North Atlantic bottom waters. These deepwater seismic horizons appear to correlate with the major events on the "relative sea-level" curve of Vail et al. for the Neogene. 相似文献
17.
During the warm early Pliocene (approximately 4.5 to 3.0 million years ago), the most recent interval with a climate warmer than today, the eastern Pacific thermocline was deep and the average west-to-east sea surface temperature difference across the equatorial Pacific was only 1.5 +/- 0.9 degrees C, much like it is during a modern El Ni?o event. Thus, the modern strong sea surface temperature gradient across the equatorial Pacific is not a stable and permanent feature. Sustained El Ni?o-like conditions, including relatively weak zonal atmospheric (Walker) circulation, could be a consequence of, and play an important role in determining, global warmth. 相似文献
18.
Legeckis R 《Science (New York, N.Y.)》1977,197(4309):1179-1181
During 1975, westward-moving long waves with a period of about 25 days and a wavelength of 1000 kilometers were observed at a sea surface temperature front in the equatorial Pacific on infrared images obtained by a geostationary environmental satellite system. The absence of these waves during 1976, and the above-average equatorial sea surface temperatures during 1976, may be related to a decrease in the southeasterly trade winds during that year. 相似文献
19.
Dimethyl sulfide (DMS) has been identified as the major volatile sulfur compound in 628 samples of surface seawater representing most of the major oceanic ecozones. In at least three respects, its vertical distribution, its local patchiness, and its distribution in oceanic ecozones, the concentration of DMS in the sea exhibits a pattern similar to that of primary production. The global weightedaverage concentration of DMS in surface seawater is 102 nanograms of sulfur (DMS) per liter, corresponding to a global sea-to-air flux of 39 x 10(12) grams of sulfur per year. When the biogenic sulfur contributions from the land surface are added, the biogenic sulfur gas flux is approximately equal to the anthropogenic flux of sulfur dioxide. The DMS concentration in air over the equatorial Pacific varies diurnally between 120 and 200 nanograms of sulfur (DMS) per cubic meter, in agreement with the predictions of photochemical models. The estimated source flux of DMS from the oceans to the marine atmosphere is in agreement with independently obtained estimates of the removal fluxes of DMS and its oxidation products from the atmosphere. 相似文献
20.
The surface of the ice-age Earth 总被引：1，自引：0，他引：1
CLIMAP Project Members 《Science (New York, N.Y.)》1976,191(4232):1131-1137
In the Northern Hemisphere the 18,000 B.P. world differed strikingly from the present in the huge land-based ice sheets, reaching approximately 3 km in thickness, and in a dramatic increase in the extent of pack ice and marine-based ice sheets. In the Southern Hemisphere the most striking contrast was the greater extent of sea ice. On land, grasslands, steppes, and deserts spread at the expense of forests. This change in vegetation, together with extensive areas of permanent ice and sandy outwash plains, caused an increase in global surface albedo over modern values. Sea level was lower by at least 85 m. The 18,000 B.P. oceans were characterized by: (i) marked steepening of thermal gradients along polar frontal systems, particularly in the North Atlantic and Antarctic; (ii) an equatorward displacement of polar frontal systems; (iii) general cooling of most surface waters, with a global average of -2.3 degrees C; (iv) increased cooling and up-welling along equatorial divergences in the Pacific and Atlantic; (v) low temperatures extending equatorward along the western coast of Africa, Australia, and South America, indicating increased upwelling and advection of cool waters; and (vi) nearly stable positions and temperatures of the central gyres in the subtropical Atlantic, Pacific, and Indian oceans. 相似文献