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Title: Vertex: Phytoplankton/iron studies in the Gulf of Alaska,
Description: VERTEX studies were performed in the Gulf of Alaska in order to test the hypothesis that iron deficiency was responsible for the phytoplankton's failure to remove major plant nutrients from these waters. In view of the observed Fe distributions and the results of phytoplankton Fe enrichment experiments, it was concluded that Gulf of Alaska atmospheric Fe input rates are sufficient to support moderately high rates of primary productivity; however, not enough Fe is available to support the high growth rates that would lead to normal major nutrient depletion. Enhanced Fe input does occur along the Alaska continental margin, where normal NO 3 surface depletion is observed. Coccolithophorids appear to be best able to cope with low Fe conditions; however, they cannot compete with diatoms when Fe is readily available. Iron may be more important than available N in determining global rates of phytoplankton new production. Offshore Pacific Ocean water, replete with major nutrients, appears to be infertile without supplemental iron from the atmosphere or continental margin. © 1989., Cited By (since 1996):399, ,
Author: Martin, Gordon, Fitzwater, Broenkow
Date: 1989-01-01T00:00:00Z

Title: Iron in north-east Pacific waters,
Description: Although Fe is an element of great biological 1 and geochemical 2 importance, little is known about its distribution in the sea. The reasons for this are: (1) contamination is extremely difficult to avoid during sampling and laboratory procedures, not only because of man's wide use of this element, but also because it is fourth most abundant element in the Earth's crust (5.63%) 3; (2) the chemistry of Fe is very complex, and its form (or forms) in seawater is poorly known, hence whether one preconcentration technique will work for existing species is questionable. Iron also appears to be very insoluble 4 in oxygenated ocean water, and most (90%) 5 precipitates out in association with dissolved organics during estuarine mixing processes 5-8. Indeed, some argue that truly dissolved Fe does not exist in seawater and that the fraction found in filtrates is totally colloidal 9. We have been attempting oceanic dissolved Fe measurements for the past four years and report here three vertical Fe profiles (Fig. 1) that have the following features in common: Fe is severely depleted (0.15-0.30 nmol kg -1) in surface waters; Fe maxima (up to 2.6 nmol kg -1) occur in association with oxygen minima; and, Fe levels appear to vary little in mid-depth waters (0.5-1.0 nmol kg -1)., Cited By (since 1996):33, ,
Author: Gordon, Martin, Knauer
Date: 1982-01-01T00:00:00Z

Title: Iron deficiency limits phytoplankton growth in Antarctic waters,
Description: Enrichment experiments were performed in the Ross Sea to test the hypothesis that iron deficiency is responsible for the phytoplankton's failure to use up the luxuriant major nutrient supplies found in these and all other offshore Antarctic ocean waters. The results suggest that Fe deficiency is the primary reason that the present-day southern ocean biological pump is shut off. In contrast, iron was 50 times more abundant during the last glacial maximum; greater Fe availability may have stimulated the biological pump and contributed to the ice age drawdown of atmospheric CO 2. These results also imply that large-scale southern ocean Fe fertilization is feasible, at least in terms of the total amounts of Fe required; i.e., 100 000 to 500 000 tons yr -1., Cited By (since 1996):277, , , Downloaded from: http://onlinelibrary.wiley.com/doi/10.1029/GB004i001p00005/pdf (9 June 2014).
Author: Martin, Fitzwater, Gordon
Date: 1990-01-01T00:00:00Z

Title: The case for iron,
Description: Excess major nutrients occur in offshore areas ranging from the tropical equatorial Pacific to the polar Antarctic. In spite of the great ecological differences in these environments, they share a common trait: iron deficiency. All of these areas are far from Fe-rich terrestrial sources and atmospheric dust loads in these regions are amongst the lowest in the world. Experiments were performed in three nutrient-rich areas: The Gulf of Alaska, the Ross Sea, and the equatorial Pacific. In general, populations without added Fe doubled at rates 11-40% of the expected maxima at various temperatures. The addition of nanomole quantities of Fe increased these doubling rates by factors of 2-3. In spite of the lack of Fe, tightly coupled phytoplankton/zooplankton communities seem to inhabit these major nutrient-rich areas. -from Authors, Cited By (since 1996):341, Oceanography, , , Downloaded from: aslo.org/lo/toc/vol_36/issue_8/1793.pdf (16 June 2014).
Author: Martin, Gordon, Fitzwater
Date: 1991-01-01T00:00:00Z

Title: Cobalt in north-east Pacific waters,
Description: Significant understanding has been gained recently about the biogeochemical cycling of trace metals in the ocean. This knowledge has mostly resulted from the accurate measurement of dissolved species in oceanic water columns. We report here that cobalt's vertical distribution is similar to that exhibited 1-3 by Mn; that is, its surface enrichment/deep depletion (Fig. 1). However, amounts of Co (1-7 ng 1 -1) are ∼10-20 times less than those for Mn (Table 1), as might be expected from crustal abundance estimates 4 for these elements (Mn=950; Co=25 μg per g). The similarity between Mn and Co profiles implies the same biogeochemical pathways. The Co excess in nearshore surface waters probably results from continental weathering input processes, as suggested by the remarkable Co-salinity mirror-image relationship shown in Fig. 1, and the Co-salinity scatter diagram in Fig. 2a. The steady decrease in Co concentrations also indicates that Co is usually scavenged rather than regenerated at depth, as is the case with Mn (Fig. 1; Table 1). © 1982 Nature Publishing Group., Cited By (since 1996):47 Oceanography, ,
Author: Knauer, Martin, Gordon
Date: 1982-01-01T00:00:00Z

Title: Iron, nutrient and phytoplankton biomass relationships in upwelled waters of the California coastal system,
Description: We report measurements of dissolvable and particulate iron, particulate Al, nutrients and phytoplankton biomass in surface waters during the termination of one upwelling event and the initiation of a second event in August 2000. These events occurred in the area of the Año Nuevo upwelling center off the coast of central California. The first event was observed after ∼8 days of continuous upwelling favorable winds, while the second event was observed through the onset of upwelling favorable winds to wind reversals ∼3 days later. Coincident with the upwelling signatures of low temperature and high salinity were significantly elevated concentrations of nitrate and silicate with average concentrations greater than 15 and 20 μM, respectively, during both upwelling events. Dissolvable Fe concentrations (TD-Fe) were significantly higher in the second event, 6.5 versus 1.2 nM Fe found in the first event. Nitrate was reduced by ∼5 μM day-1 within this second upwelled plume as compared to a drawdown of ∼2 μM day-1 within the first plume. Silicate was reduced in a ratio of 1.2 mol Si:mol NO3 in the high Fe waters of the second plume as compared to a ratio of 2.2 in the lower Fe waters of the first plume. The observed differences in nutrient utilization are consistent with some degree of iron limitation. The area of increased dissolvable Fe in the second upwelling event was coincident with elevated particulate Fe concentrations, indicating the particulate pool as a possible source of the observed increase in TD-Fe. The elevated particulate Fe in surface waters was a result of resuspended sediments in the bottom boundary layer (BBL) of the shallow shelf being transported to the surface during upwelling. Particulate (and dissolvable) iron concentrations were significantly reduced as upwelling continued. This was most probably due to a decoupling of the BBL from upwelled source waters as the upwelling front moved offshore and/or reduced turbulence in the BBL as upwelling continued. The observed reduction in both particulate and dissolvable Fe, as upwelling continued to deliver macronutrients to surface waters, may result in varying levels of Fe limitation., Cited By (since 1996):35, CODEN: CSHRD, ,
Author: Fitzwater, Johnson, Elrod, Ryan, Coletti, Tanner, Gordon, Chavez
Date: 2003-01-01T00:00:00Z

Title: Mytilus californianus as a bioindicator of trace metal pollution: Variability and statistical considerations,
Description: Trace metal variability was evaluated in two populations of Mytilus californianus through the analysis of individual specimens. Samples were collected for two areas in the Southern California Bight and analysed for their Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn content. Analysis of the data revealed that population variability was not the same between the two sites, indicating that variability may need to be evaluated for each population (site) studied. In general, the analysis of 10 to 30 individuals was necessary to yield maximum resolution in terms of trace metal concentrations between population means while maintaining cost effectiveness., Cited By (since 1996):29, CODEN: MPNBA, ,
Author: Gordon, Knauer, Martin
Date: 1980-01-01T00:00:00Z

Title: Iron in Antarctic waters,
Description: WE are testing the hypothesis that Antarctic phytoplankton suffer from iron deficiency 1-3 which prevents them from blooming and using up the luxuriant supplies of major nutrients found in vast areas of the southern ocean. Here we report that highly productive 4 (∼3 g Cm -2 day -1), neritic Gerlache Strait waters have an abundance of Fe (7.4 nmol kg -1) which facilitates phytoplankton blooming and major nutrient removal, while in low-productivity 4 (∼0.1 g Cm -2 day -1), offshore Drake Passage waters, the dissolved Fe levels are so low (0.16 nmol kg -1) that the phytoplankton are able to use less than 10% of the major nutrients available to them. The verification of present-day Fe deficiency is of interest as iron-stimulated phytoplankton growth may have contributed to the drawing down of atmospheric CO 2 during glacial maxima 2,3; it is also important because oceanic iron fertilization aimed at the enhancement of phytoplankton production may turn out to be the most feasible method of stimulating the active removal of greenhouse gas CO 2 from the atmosphere, if the need arises (J.H.M., manuscript in preparation)., Cited By (since 1996):449, CODEN: NATUA, ,
Author: Martin, Gordon, Fitzwater
Date: 1990-01-01T00:00:00Z

Title: Primary productivity and trace-metal contamination measurements from a clean rosette system versus ultra-clean Go-Flo bottles,
Description: Primary productivity rates, measured during the 1992 United States Joint Global Ocean Flux Study (U.S. JGOFS) Equatorial Pacific (EqPac) process study with a new Trace-Metal clean rosette system (TM rosette) designed to be trace-metal clean, agreed within 5% with those determined using ultra-clean procedures that were previously shown to be trace-metal clean. The TM rosette system did not inhibit phytoplankton primary productivity rates. Using the TM rosette system, there was no contamination of Co, Ni, Cu, Cd or Pb, and only slight contamination of Fe and Zn, relative to ultra-clean collection. However, the slight contaminations were below levels that affect primary productivity rates. Therefore, systematic phytoplankton inhibition by trace-metal contamination appears to have been successfully eliminated with water collected using the TM rosette system. © 1995., Cited By (since 1996):16, CODEN: DSROE, ,
Author: Sanderson, Hunter, Fitzwater, Gordon, Barber
Date: 1995-01-01T00:00:00Z

Title: Silver distributions and fluxes in north-east Pacific waters,
Description: In recent years, significant knowledge has been gained about the oceanic distributions of several trace elements 1,2. However, relatively little is known about amounts of Ag in the ocean, and how this element cycles through it. We report here that Ag levels are relatively low near the surface (∼1 pmol kg -1), and that concentrations more or less steadily increase with depth; for example, 23 pmol kg -1 at 2,440 m, the deepest sample we collected. In general, Ag depth profiles are similar to those observed for Cu (Fig. 1). The near-surface cycles of Ag appears to be involved with particulate organic matter uptake-sinking-regeneration processes. © 1983 Nature Publishing Group., Cited By (since 1996):39, Oceanography, ,
Author: Martin, Knauer, Gordon
Date: 1983-01-01T00:00:00Z

Title: Surface ocean-lower atmosphere interactions in the Northeast Pacific Ocean Gyre: Aerosols, iron, and the ecosystem response,
Description: Here we report measurements of iron and aluminum in surface and subsurface waters during late March and late May of 2001 on transects between central California and Hawaii. A large cloud of Asian dust was detected during April 2001, and there was a clear signal in surface water iron due to aerosol deposition on the May transect. Iron and aluminum concentrations increased synchronously by 0.5 and 2 nM along the southern portion of the transect, which includes the Hawaii Ocean Time series (HOT) station, from background values in March (0.1 to 0.2 nM Fe). These changes occured in a ratio that is close to the crustal abundance ratio of the metals, which indicates a soil aerosol source. A vertical profile of dissolved iron was also measured at the HOT station in late April and this profile also shows a large increase near the surface. Direct observations of aerosol iron concentration at Mauna Loa Observatory on Hawaii indicate that aerosol concentrations were significantly lower than climatological values during this period. Soil aerosol concentrations along the transect were estimated using the real-time Navy Aerosol Analysis and Prediction System (NAAPS). The NAAPS results show a large meridional gradient with maximum concentrations in the boundary layer north of 30°N. However, the deposition of iron and aluminum to surface waters was highest south of 25°N, near Hawaii. There were only weak signals in the ecosystem response to the aerosol deposition., Cited By (since 1996):64, Oceanography, , , Downloaded from: http://onlinelibrary.wiley.com/doi/10.1029/2002GB002004/pdf (16 June 2014).
Author: Johnson, Elrod, Fitzwater, Plant, Chavez, Tanner, Gordon, Westphal, Perry, Wu, Karl
Date: 2003-01-01T00:00:00Z

Title: Iron-enrichment bottle experiments in the equatorial Pacific: Responses of individual phytoplankton cells,
Description: Iron-enrichment bottle experiments were monitored using flow cytometry to investigate the hypothesis that phytoplankton in the equatorial Pacific are iron-limited. Iron-enriched Synechococcus, ultraphytoplankton, nanophytoplankton, pennate diatoms, and coccolithophorids had higher fluorescence and/or forward light scatter per cell than control cells; for Prochlorococcus the trends were the same although the differences were not significant. This suggests that most phytoplankton cells were physiologically affected by the low iron concentrations in this region. However, only pennate diatoms showed significant increases in cell concentrations due to iron enrichment. The sum of chlorophyll fluorescences of individual cells measured by flow cytometry yielded patterns similar to those of extracted bulk chlorophyll, with increases of up to 10-fold in iron-enriched bottles but at most 3-fold in control bottles; pennate diatoms accounted for most of the increase in chlorophyll in iron-enriched bottles., Cited By (since 1996):39, CODEN: DSROE, ,
Author: Zettler, Olson, Binder, Chisholm, Fitzwater, Gordon
Date: 1996-01-01T00:00:00Z