An equatorial pacific ocean source of atmospheric mercury

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.     

Biological consequences of the 1975 el nino

The weak El Ni?o event of 1975 had a clearly defined effect on the biological productivity of the southeastern tropical Pacific. During February and March 1975, warm (27 degrees C) water of low salinity (33.5 parts per thousand) and low nutrient content extended south across the equator east of the Galápagos Islands, replacing the nutrient-rich water normally supplied by equatorial upwelling. Equatorial primary production was less than 0.2 gram of carbon per square meter per day, one-fifth of the normal value. At the maximum development of the 1975 event, the coastal region of Peru continued to have strong nearshore upwelling with primary production values greater than 2.5 grams of carbon per square meter per day, although the zone of high production was confined to a 250-kilometer-wide band, one-half its normal width. The biological effects of the 1975 event were short-lived; in April and May 1975 the equatorial region had begun to reestablish its normal levels of primary production.     

Long-range atmospheric transport of soil dust from Asia to the tropical north pacific: temporal variability

The concentration of airborne soil dust at Enewetak Atoll(11 degrees N, 162 degrees E) in April 1979 was 2.3 micrograms per cubic meter but decreased steadily to 0.02 microgram per cubic meter over the next 5 months. The spring dust is probably derived from China; its deposition rate ( approximately 0.3 millimeter per 1000 years) suggests that it may be a significant contributor to the deep-sea sediments of the North Pacific.     

High-frequency skywave radar measurements of hurricane anita

We tracked and monitored hurricane Anita over a 5-day period by using the SRI-operated Wide Aperture Research Facility (WARF) high-frequency skywave radar. The WARF-derived positions for Anita agreed to within +/- 19 kilometers of the coincident temporal positions along the National Hurricane Center's smooth track. Hurricane Anita passed near the open ocean-moored buoy EB-71 of the National Oceanic and Atmospheric Administration, and measurements of wind direction, wind speed, and significant wave height made during this period at the WARF and in situ at the buoy showed agreement of 7 degrees , 0.4 meter per second, and 0.5 meter, respectively. The WARF estimates of longshore coastal surface currents showed good agreement with measurements made at a moored current meter.     

Evolution of sea surface temperature in the somali basin during the southwest monsoon of 1979

Satellite and research vessel observations of sea surface temperature during the southwest monsoon of 1979 show the development of large wedge-shaped areas of cold water along the Somali coast at both 5 degrees and 10 degrees N during June and July. The cold water associated with the large northern and southern Somali eddy systems could be traced several hundred kilometers offshore. By late August the cold wedge at 5 degrees N translated northeastward as far as 10 degrees N at speeds of 15 to 30 centimeters per second, indicating a coalescence of the systems.     

Radar characteristics of viking 1 landing sites

Radar observations of Mars at centimeter wavelengths in May, June, and July 1976 provided estimates of surface roughness and reflectivity in three potential landing areas for Viking 1. Surface roughness is characterized by the distribution of surface landing slopes or tilts on lateral scales of the order of 1 to 10 meters; measurements of surface reflectivity are indicators of bulk surface density in the uppermost few centimeters. By these measures, the Viking 1 landing site at 47.5 degrees W, 22.4 degrees N is rougher than the martian average, although it may be near the martian average for elevations accessible to Viking, and is estimated to be near the Mars average in reflectivity. The AINW site at the center of Chryse Planitia, 43.5 degrees W, 23.4 degrees N, may be an area of anomalous radar characteristics, indicative of extreme, small-scale roughness, very low surface density, or a combination of these two characteristics, Low signal-to-noise ratio observations of the original Chryse site at 34 degrees W, 19.5 degrees N indicate that that area is at least twice as rough as the Mars average.     

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.     

Seasonality and interaction of biogenic and lithogenic particulate flux at the panama basin

Time-series sediment traps were deployed for an entire year at three depths (890, 2590, and 3560 meters) at a deepwater station (3860 meters) in the Panama Basin. The amount of horizontal and lithogenic particulate material arriving at the three depths was seasonally pulsed and directly reflected changes in surface primary production. Two spikes of organic flux were simultaneously recorded at all three depths: (i) a period of high productivity during regional upwelling in February through March and (ii) an unusual bloom of a single species of coccolithophorid during June through July. This latter spike delivered approximately 25 grams of coccolith per square meter of area at a depth of 3860 meters during less than 60 days. The flux of lithogenic particles increased with increasing depth and was seasonally correlated to surface production and current direction, and not to the detritus discharged in river flow. The data suggest that suspended clays are efficiently scavenged from the water column by rapidly sinking organic aggregates.     

Contact electrification and adhesion between dissimilar materials

Simultaneous measurements of surface force and surface charge demonstrate strong attraction due to the spontaneous transfer of electrical charge from one smooth insulator (mica) to another (silica) as a result of simple, nonsliding contact in dry nitrogen. The measured surface charge densities are 5 to 20 millicoulombs per square meter after contact. The work required to separate the charged surfaces is typically 6 to 9 joules per square meter, comparable to the fracture energies of ionic-covalent materials. Observation of partial gas discharges when the surfaces are approximately 1 micrometer apart gives valuable insight into the charge separation processes underlying static electrical phenomena in general.     

采伐对集材道表层土壤主要化学性质影响的初步研究

基于运载量对集材道表层土壤物理性质影响的研究,将运载量限定为1.0m^3/趟,研究采伐作业1 a后集材道表层土壤主要化学性质的变化情况。研究结果表明：1 a后,集材道表层土壤主要化学性质指标均有不同程度的变化（降低）,其中以速效N、速效K含量的变化程度最高,均表现出接近50%的损失率,土壤pH值的变化程度最低,其他化学性质变化幅度为10%-20%。速效养分的大量损失,不利于森林环境的恢复。     

Florida current: low-frequency variability as observed with moored current meters during april 1982 to june 1983

A 1-year time series of volume transport through the Florida Straits near 27 degrees N was derived from an array of five subsurface current meter moorings. The transport estimates, determined on the basis of constant shear extrapolation of the subsurface velocities to the surface, are in good agreement with transports derived from submarine cable and Pegasus measurements. The annual transport cycle in 1982-1983 is complicated by large-amplitude fluctuations on time scales of 1 to 3 weeks, but it does exhibit a transport maximum in summer and a minimum in fall-winter, consistent with historical results and of similar magnitude. The energy density spectrum of transports is continuous with a slope of about -1.5 and does not show a gap between the periods of weeks and seasonal. Evidence was found for atmospheric forcing of transport fluctuations, with highest coherence between transport and the local meridional wind stress at periods of 10 and 15 days during the summer and 5 and 40 days during the winter.     

Supernova remnant w-44: observations at 8350 megacycles per second

The region of W-44 was mapped at 8350 megacycles per second. The degree of linear polarization of the most intense portion of W-44 integrated over the 10.8-minute-of-arc beam was 11+/-2 percent at position angle 45 degrees +/-5 degrees . This high degree of polarization is further evidence that W-44 is a supernova remnant. The integrated flux density of (95+/-25) x 10(-26) watt per square meter per cycle per second for this source is consistent with measurements at lower frequencies extrapolated with the use of a spectral index of-0.44, obtained by other observers. In addition, the compact source 3 minutes of right ascension west of W-44 was unpolarized, within the error of measurement. The flux density of (23+/-6)x 10(-26) watt per square meter per cycle per second determined for it along with the results of other observers indicate that this source has a thermal spectrum.     

Magnetic Anomalies over the Mid-Atlantic Ridge near 27{degrees}N

Ten magnetic profiles across the mid-Atlantic ridge near 27 degrees N show trends that are parallel to the ridge axis and symmetrical about the ridge axis. The configuration of magnetic bodies that could account for the pattern supports the Vine and Matthews hypothesis for the origin of magnetic anomalies over oceanic ridges. A polarity-reversal time scale inferred from models for sea-floor spreading in the Pacific-Antarctic ridge and radiometrically dated reversals of the geomagnetic field indicates a spreading rate of 1.25 centimeters per year during the last 6 million years and a rate of 1.65 centimeters per year between 6 and 10 million years ago. A similar analysis of more limited data over the mid-Atlantic ridge near 22 degrees N also indicates a change in the spreading rate. Here a rate of 1.4 centimeters per year appears to have been in effect during the last 5 million years; between 5 and 9 million years ago, an increased rate of 1.7 centimeters per year is indicated. The time of occurrence and relative magnitude of these changes in the spreading rate, about 5 to 6 million years ago and 18 to 27 percent, respectively, accords with the spreading rate change implied for the Juan de Fuca ridge in the northeast Pacific.     

Kinematics of the asal rift (djibouti) determined from the deformation of fieale volcano

Because of its subaerial exposure the Asal rift segment provides an exceptional opportunity to quantify the deformation field of an active rift and assess the contribution of tectonics and volcanism to rifting processes. The present topography of the Asal rift results from the tectonic dismemberment during the last 100,000 years of a large central volcanic edifice that formed astride the rift zone 300,000 to 100,000 years ago. Three-dimensional deformation of this volcano has been quantified from the combined analysis of the topography and geology. The analysis indicates that spreading at 17 to 29 millimeters per year in a N40 degrees +/- 5 degrees E direction accounts for most of the separation between Arabia and Somalia. The small topographic subsidence relative to extension suggests that tectonic thinning of the crust has been balanced by injection and underplating of magmatic material of near crustal density. The methodology developed in this study could also be applied to quantify deformation in relatively inaccessible areas where the main available information is topography or bathymetry.     

Calcium carbonate production, coral reef growth, and sea level change

Shallow, seaward portions of modern coral reefs produce about 4 kilograms of calcium carbonate per square meter per year, and protected areas produce about 0.8 kilogram per square meter per year. The difference is probably largely a function of water motion. The more rapid rate, equivalent to a maximum vertical accretion of 3 to 5 millimeters per year, places an upper limit on the potential of modern coral reef communities to create a significant vertical structure on a rising sea.     

台湾海峡西北部海坛岛东南沿岸上升流对表层沉积硅藻的影响

[目的]探讨台湾海峡西北部海坛岛东南沿岸上升流对表层沉积硅藻的影响。[方法]以台湾海峡西北部海坛岛东南沿岸的表层沉积硅藻为材料,对其进行筛选、制片、观察,研究其属种分布特征和上升流对其的影响。[结果]按照表层沉积硅藻的丰度分布特征,将其分为三个研究区,以柱状小环藻、具槽直链藻和波状辐裥藻为主要的优势种群。结合温度、盐度的资料,可以得出海坛岛东南沿岸海域存在上升流。[结论]该研究为进一步探讨海坛岛东南沿岸海域表层沉积硅藻与上升流的关系提供了科学依据。     

Charge Transfer between Raindrops: Microwave temperatures of thunderstorms can be deduced from radiation emitted by colliding drops

Electric discharges between free-falling drops have been observed and studied quantitatively in the laboratory. These data and information from terrestrial thunderstorms suggest that augmentation of the UHF temperature of thunderstorms by discharges could amount to 117 degrees K. If similar discharges occurred in the atmosphere or on the surface (or in both regions) of Venus, 1.4 x 10(6) discharges per second per square meter would be required to produce the microwave temperature observed (approximately 650 degrees K). It is not probable that such radiation supplies the whole microwave temperature observed; some fraction must be true thermal radiation as described by Plummer and Strong (9), in which case the probable number of required discharges is reduced accordingly.     

Hydroxyl radical photoproduction in the sea and its potential impact on marine processes

Photochemical production rates and steady-state concentrations of hydroxyl radicals (.OH) were measured in sunlight-irradiated seawater. Values ranged from 110 nanomolar per hour and 12 x 10(-18) molar in coastal surface water to 10 nanomolar per hour and 1.1 x 10(-18) molar in open ocean surface water. The wavelengths responsible for this production are in the ultraviolet B region (280 to 320 nanometers) of the solar spectrum. Dissolved organic matter (DOM) appears to be the main source for .OH over most of the oceans, but in upwelling areas nitrite and nitrate photolysis may also be important. DOM in the deep sea is degraded more readily by .OH (and its daughter radicals), by a factor of 6 to 15, than is DOM in open-ocean surface water. This finding may in part bear on major discrepancies among current methods for measuring dissolved organic carbon in seawater.     

A potent greenhouse gas identified in the atmosphere: SF(5)CF(3)

We detected a compound previously unreported in the atmosphere, trifluoromethyl sulfur pentafluoride (SF(5)CF(3)). Measurements of its infrared absorption cross section show SF(5)CF(3) to have a radiative forcing of 0.57 watt per square meter per parts per billion. This is the largest radiative forcing, on a per molecule basis, of any gas found in the atmosphere to date. Antarctic firn measurements show it to have grown from near zero in the late 1960s to about 0.12 part per trillion in 1999. It is presently growing by about 0.008 part per trillion per year, or 6% per year. Stratospheric profiles of SF(5)CF(3) suggest that it is long-lived in the atmosphere (on the order of 1000 years).     

Growth of prochlorococcus, a photosynthetic prokaryote, in the equatorial pacific ocean

The cell cycle of Prochlorococcus, a prokaryote that accounts for a sizable fraction of the photosynthetic biomass in the eastern equatorial Pacific, progressed in phase with the daily light cycle. DNA replication occurred in the afternoon and cell division occurred at night. Growth rates were maximal (about one doubling per day) at 30 meters and decreased toward the surface and the bottom of the ocean. Estimated Prochlorococcus production varied between 174 and 498 milligrams of carbon per square meter per day and accounted for 5 to 19 percent of total gross primary production at the equator. Because Prochlorococcus multiplies close to its maximum possible rate, it is probably not severely nutrient-limited in this region of the oceans.