PO4, NO3, NO2 surface concentrations along the US GEOTRACES North Atlantic Transect from the R/V Knorr KN199-04, KN199-05 cruises in the subtropical N. Atlantic during 2010 (U.S. GEOTRACES NAT project)

Dataset: GT10 - Nanomolar Nutrients - SurfacePO4, NO3, NO2 surface concentrations along the US GEOTRACES North Atlantic Transect from the R/V Knorr KN199-04, KN199-05 cruises in the subtropical N. Atlantic during 2010. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3470NSF Division of Ocean Sciences (NSF OCE) OCE-0926423, NSF Division of Ocean Sciences (NSF OCE) OCE-092609

Surface arsenic, antimony speciation, and alkaline phosphatase activity along with US GEOTRACES North Atlantic Transect from the R/V Knorr KN199-04, KN199-05 cruises in the subtropical N. Atlantic during 2010 (U.S. GEOTRACES NAT project)

Dataset: GT10 - As AP Surface TransectsData for the concentrations of the dissolved (<0.4 µm) arsenic species: total inorganic As (III+V), arsenite (AsIII), arsenate (AsV), monomethyl As, and dimethyl As; and the activity of the enzyme alkaline phosphatase (unfiltered) on the surface transect. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3520NSF Division of Ocean Sciences (NSF OCE) OCE-0926423, NSF Division of Ocean Sciences (NSF OCE) OCE-092609

Surface transects for arsenic speciation, antimony speciation, and alkaline phosphatase activity from R/V Knorr cruise KN204-01 in the Subtropical North Atlantic Ocean in 2011 (U.S. GEOTRACES NAT project)

Dataset: GT11 - As AP Surface TransectsSurface transects for arsenic speciation, antimony speciation, and alkaline phosphatase activity. Data for the concentrations of the dissolved (<0.4 µm) arsenic species: total inorganic As (III+V), arsenite (AsIII), As(V), monomethyl As, dimethyl As, and the activity of the enzyme alkaline phosphatase (unfiltered). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3830NSF Division of Ocean Sciences (NSF OCE) OCE-0926423, NSF Division of Ocean Sciences (NSF OCE) OCE-092609

Intercalibraton in Chemical Oceanography-- Getting The Right Number

Intercalibration has a strict metrological definition, but in brief, it\u27s an open sharing of methods and results between laboratories to achieve the most accurate data with the fewest random and systematic errors. In the field of chemical oceanography where concentrations of many constituents can be in the nano- to picomolar range, the salt water matrix can be difficult to analyze, and knowing the exact concentrations, or even chemical forms, of biologically required elements is essential, intercalibration is a very relevant and needed tool. Implementing it is not simple because errors can occur at any step in the process of taking a water or particle sample, handling and processing it, and finally analyzing it and treating the resulting data. The international GEOTRACES program provides a good example of implementing intercalibration for studies of dissolved and particulate trace elements and isotopes, and is described here

Metalloids in Wet Deposition on Bermuda: Concentrations, Sources, and Fluxes

The concentrations of antimony, arsenic, and selenium were determined in wet deposition samples collected on a daily (event) basis from 1988 to 1990 on Bermuda as a part of the Atmosphere/Ocean Chemistry Experiment (AEROCE). Isentropic back trajectories were used to identify air masses that passed over North America (59% of the events), Europe or North Africa (8%), or were largely marine in origin (33% of the events). The North American trajectories had the highest volume-weighted average (VWA) concentrations and crustal enrichment factors for the three metalloids; the As/Se ratio and good correlations with acidity suggest inputs from fossil fuel combustion. The Euro-African trajectories had the lowest VWA concentrations and enrichment factors that approached crustal values, indicating mineral aerosol inputs; values for marine events fell between these two extremes. The atmospheric flux of metalloids to the western Atlantic Ocean represents a major source of these elements in surface waters (up to 100% for Sb and Se; up to 61% for As) and a corresponding sink in their global atmospheric budgets

Trace Elements in Estuarine and Coastal Waters: U.S. Studies from 1986-1990

The use of specialized analytical techniques, field studies, controlled laboratory experiments, and geochemical modeling have allowed U.S. investigators to expand our understanding of trace element cycling in coastal waters and estuaries. Considerable emphasis has been placed on quantifying the flux of trace elements within and through the coastal zone. In addition, substantial progress has been made in identifying the chemical speciation of many trace elements, providing a linkage between the geochemical and biochemical behavior of these elements. Another significant advance has been the use of trace elements as tracers of geochemical processes and water masses in the coastal environment

Sources And Cycling of Carbonyl Sulfide in the Sargasso Sea

The cycling of the radiatively important gas carbonyl sulfide (OCS) was studied in surface waters of the Sargasso Sea. In August 1999, surface OCS concentrations averaged 8.6 pmol L-1, showed minor diel variations, and varied little with depth. An OCS precursor, total dissolved organic sulfur (DOS), was lowest at the surface (40 nmol L-1) and increased with depth. The photoproduction rate of OCS from in situ incubations averaged 9.6 pmol L-1 h-1, whereas dark production was 7.0 pmol L-1 h-1. Apparent quantum yields were 10-5-10-7 from 313-436 nm and varied with the water depth irradiated. In March 2000, there were strong diel variations in surface OCS (highest in late afternoon; overall average, 16.9 pmol L-1). Depth profiles in the afternoon showed surface water maxima and decreases with depth, whereas DOS had a surface maximum of 419 nmol L-1 and decreased with depth. Dark production was 4.0 pmol L-1 h-1. Modeling of the diel cycle suggested a photoproduction rate of 16.4 pmol L-1 h-1. Overall, the photochemical production of OCS strongly depended on DOS and chromophoric dissolved organic matter, whereas dark production was influenced by the presence of particles and perhaps microbial respiration, showing a direct biotic influence on OCS cycling

Sulfide in Surface Waters of the Western Atlantic Ocean

Using newly developed techniques, some preliminary data on hydrogen sulfide in surface waters of the western Atlantic have been obtained. Concentrations of total sulfide range from \u3c0.1 to 1.1 nmol/L, and vary on a diel basis. At these concentrations, sulfide may affect the cycling of several trace metals via the formation of stable complexes. Production of sulfide in oxygenated seawater may occur through the hydrolysis of carbonyl sulfide or by sulfate reduction within macroscopic particles in the water column. Removal mechanisms can include oxidation, complexation with particulate trace metals, and metal sulfide precipitation. However, the temporal and spatial distributions suggest a complex set of processes governing the behavior of sulfide in the surface ocean

The Marine Biogeochemistry of Selenium: A Re-Evaluation

Vertical and horizontal profiles from the North and South Pacific Oceans demonstrate the existence of three species of dissolved selenium: selenite, selenate, and organic selenide (operationally defined). In surface waters, organic selenide makes up about 80% of the total dissolved selenium, selenite concentrations are uniformly low, and selenate concentrations rise with increased vertical mixing. The organic selenide maximum (thought to consist of seleno-amino acids in peptides) coincides with the maxima of primary productivity, pigments, bioluminescence, and dissolved free amino acids. Deep ocean waters are enriched in selenite and selenate, while organic selenide is nondetectable. In suboxic waters of the tropical northeastern Pacific, organic selenide concentrations rise, while selenite values decrease. The downward flux of particulate selenium generally decreases with depth, and fluxing particulate selenium is found to be primarily in the (-2) oxidation state. These data allow a re-evaluation of the internal biogeochemical cycle of selenium. This cycle includes selective uptake, reductive incorporation, particulate transport, a multistep regeneration, and kinetic stabilization of thermodynamically unstable species