Significant discharge of CO2 from hydrothermalism associated with the submarine volcano of El Hierro Island.

The residual hydrothermalism associated with submarine volcanoes, following an eruption event, plays an important role in the supply of CO2 to the ocean. The emitted CO2 increases the acidity of seawater. The submarine volcano of El Hierro, in its degasification stage, provided an excellent opportunity to study the effect of volcanic CO2 on the seawater carbonate system, the global carbon flux, and local ocean acidification. A detailed survey of the volcanic edifice was carried out using seven CTD-pH-ORP tow-yo studies, localizing the redox and acidic changes, which were used to obtain surface maps of anomalies. In order to investigate the temporal variability of the system, two CTD-pH-ORP yo-yo studies were conducted that included discrete sampling for carbonate system parameters. Meridional tow-yos were used to calculate the amount of volcanic CO2 added to the water column for each surveyed section. The inputs of CO2 along multiple sections combined with measurements of oceanic currents produced an estimated volcanic CO2 flux = 6.0 10(5) ± 1.1 10(5 )kg d(-1) which is ~0.1% of global volcanic CO2 flux. Finally, the CO2 emitted by El Hierro increases the acidity above the volcano by ~20%.

Assessing community health center (CHC) assets and capabilities for recruiting physicians: the CHC Community Apgar Questionnaire.

INTRODUCTION: Recent trends suggest that community health centers (CHCs) may experience a shortage of qualified physicians required to meet current and future demand. The purpose of this study was to develop an evaluation instrument, the CHC Community Apgar Questionnaire (CHC CAQ) for Idaho CHCs to use in physician recruitment. METHODS: The instrument was developed based on the Critical Access Hospital Community Apgar Questionnaire (CAH CAQ). The CHC CAQ was customized for CHC use and 12 new factors were identified for substitution in the CHC instrument. All 13 CHCs in Idaho participated in this study. One site was chosen per CHC if the CHC had multiple service locations. In each community, the administrator of the CHC and the physician with recruiting responsibilities participated individually in a structured interview. RESULTS: A total of 11 physicians and 11 administrators participated in the study. Differences were found across and within classes of factors associated with success in physician recruitment. Alpha communities, those historically having more success in physician recruitment, scored higher on CAQ metrics than less successful beta communities. No material differences were noted across physician and administrator ratings. Cumulative mean Community Apgar scores (CHC CAQ) were mostly higher in alpha communities. CONCLUSION: The CHC CAQ, like the CAH CAQ, seems to discriminate between communities with differing assets and capabilities based on historical community-specific workforce trends. This assessment may suggest which factors are most important for a community to address with limited available resources and which factors are useful in marketing their CHC to prospective physicians.

A sea-floor spreading event captured by seismometers.

Two-thirds of Earth's surface is formed at mid-ocean ridges, yet sea-floor spreading events are poorly understood because they occur far beneath the ocean surface. At 9 degrees 50'N on the East Pacific Rise, ocean-bottom seismometers recently recorded the microearthquake character of a mid-ocean ridge eruption, including precursory activity. A gradual ramp-up in activity rates since seismic monitoring began at this site in October 2003 suggests that eruptions may be forecast in the fast-spreading environment. The pattern culminates in an intense but brief (approximately 6-hour) inferred diking event on 22 January 2006, followed by rapid tapering to markedly decreased levels of seismicity.

Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean.

Submarine hydrothermal venting along mid-ocean ridges is an important contributor to ridge thermal structure, and the global distribution of such vents has implications for heat and mass fluxes from the Earth's crust and mantle and for the biogeography of vent-endemic organisms. Previous studies have predicted that the incidence of hydrothermal venting would be extremely low on ultraslow-spreading ridges (ridges with full spreading rates <2 cm x yr(-1)-which make up 25 per cent of the global ridge length), and that such vent systems would be hosted in ultramafic in addition to volcanic rocks. Here we present evidence for active hydrothermal venting on the Gakkel ridge, which is the slowest spreading (0.6-1.3 cm x yr(-1)) and least explored mid-ocean ridge. On the basis of water column profiles of light scattering, temperature and manganese concentration along 1,100 km of the rift valley, we identify hydrothermal plumes dispersing from at least nine to twelve discrete vent sites. Our discovery of such abundant venting, and its apparent localization near volcanic centres, requires a reassessment of the geologic conditions that control hydrothermal circulation on ultraslow-spreading ridges.

The effect of magmatic activity on hydrothermal venting along the superfast-spreading East pacific rise.

A survey of hydrothermal activity along the superfast-spreading (approximately 150 millimeters per year) East Pacific Rise shows that hydrothermal plumes overlay approximately 60 percent of the ridge crest between 13 degrees 50' and 18 degrees 40'S, a plume abundance nearly twice that known from any other rige portion of comparable length. Plumes were most abundant where the axial cross section is inflated and an axial magma chamber is present. Plumes with high ratios of volatile ((3)He, CH(4), and H(2)S) to nonvolatile (Mn and Fe) species marked where hydrothermal circulation has been perturbed by recent magmatic activity. The high proportion of volatile-rich plumes observed implies that such episodes are more frequent here than on slower spreading ridges.

Hydrothermal plume measurements: a regional perspective.

An extensive deep-tow survey around an active submarine vent field was conducted to map the three-dimensional distribution of hydrothermal emissions and calculate the hydrothermal discharge of heat and manganese. Emissions from the 10-kilometer-long vent field formed a nearly isopycnal plume about 250 meters thick and elongated in the direction of the local net current. Net export of hydrothermal discharge from both point and diffuse sources was estimated from the advective transport of the plume; the heat flux was 5.8 +/- 2.9 x 10(8) watts and the dissolved manganese flux was 0.2 +/- 0.1 moles per second. Flux measurements of this type could be expanded to encompass entire ridge segments, allowing comparison with theoretical thermal and chemical process models on a common spatial scale.

Nimbus-7 coastal zone color scanner: system description and initial imagery.

The Coastal Zone Color Scanner (CZCS) on Nimbus-7, launched in October 1978, is the only sensor in orbit that is specifically designed to study living marine resources. The initial imagery confirms that CZCS data can be processed to a level that reveals subtle variations in the concentration of phytoplankton pigments. This development has potential applications for the study of large-scale patchiness in phytoplankton distributions, the evolution of spring blooms, water mass boundaries, and mesoscale circulation patterns.

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.