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Title: Primary production, new production and vertical flux in the eastern Pacific Ocean,
Description: The sinking of participate organic matter in the ocean links food webs beneath the euphotic zone to surface primary production and is an important pathway for the downward transport of many elements 1-3. The flux of particulate organic carbon (POC) is also an important parameter in the global carbon cycle and may be related to long-term changes in atmospheric CO 24,5. In 1980, Suess 6synthesized existing measurements from sediment trap studies into a model to predict the vertical flux of POC from depth (z) and primary production (PP)6. The Suess model has become the standard for evaluating vertical flux data 7, for estimating the annual flux of POC in the ocean 8and for parameterizing ocean carbon cycle models 4,5. We present here a new model of the vertical flux of POC and particulate organic nitrogen (PON) from a set of contemporaneous measurements of PP and fluxes made during the VERTEX (Vertical Transport and Exchange) programme in the north-east Pacific. The VERTEX model indicates that PP and vertical fluxes of POC and PON, in the oligotrophic ocean are greater than previously suggested. In addition, the vertical flux of PON from the photic zone represents a measure of the PP that is supported by new nitrogen (new production) 9,10. In the north-east Pacific, new production ranged from 13 to 25% of primary production and was positively related to total PP. © 2002 Nature Publishing Group., Cited By (since 1996):144, ,
Author: Pace, Knauer, Karl, Martin
Date: 1987-01-01T00:00:00Z

Title: The effects of Cu on the adenylate energy charge of open ocean phytoplankton,
Description: The effects of short-term, acute Cu exposure (6 h) on the adenylate energy charge (EC A) of open-ocean phytoplankton populations (northeastern equatorial Pacific) were investigated. Energy charge remained at ̃0.77 over the range of Cu additions (0.025 - 5.μg l -1), even though 14C uptake and total adenylate levels (ATP + ADP + AMP) were reduced by as much as 60%. These findings suggest that EC A alone is not a sensitive indicator of acute sublethal metal effects on phytoplankton. © 1983 IRL Press Ltd., Cited By (since 1996):1, Oceanography, CODEN: JPLRD, ,
Author: Fitzwater, Knauer, Martin
Date: 1983-01-01T00:00:00Z

Title: Improvement of the pre-deployment net closure procedure used with opening/closing plankton nets,
Description: The construction of a closing device to be used during the deployment of phyto-zooplankton nets utilizing General Oceanics-type opening/closing mechanisms is described. This device (the cowl) decreases system set-up time, decreases contamination from ambient particles while waiting for deployment, protects the net from mechanical tears during descent, and increases system reliability., Cited By (since 1996):2, CODEN: JPLRD, ,
Author: Tuel, Knauer
Date: 1982-01-01T00:00:00Z

Title: Downward flux of particulate organic matter in the Ocean,
Description: Oceanographers now recognize two distinct classes of particles in seawater, broadly categorized as suspended and sinking. The former class dominates the standing stock of particulate matter in the ocean and the latter class dominates the exchange between the surface waters and greater ocean depths 1. The downward vertical flux of particulate organic matter (POM) in the open ocean exhibits a non-linear decrease with increasing water depth 2-6, and greater than 75% of the net POM loss occurs in the upper 500 m of the water column 6. Because sinking particles contain viable, metabolically active microorganisms 7-12, the process of microbial decomposition is considered to be an important mechanism controlling POM flux. This model is consistent with the observed correspondence between POM flux and dissolved inorganic carbon concentrations 13, and with the reported selective loss of biochemically labile compounds from sinking particles 14-17. From our experiments, however, we conclude that the large sinking particles are, in general, poor habitats for bacterial growth and therefore unlikely sites for the active remineralization of organic matter. Our results require a shift in the emphasis of current ideas of particle decomposition from microbes attached to rapidly sinking particles to the microbial populations which are either free-living in the water column or attached to suspended (non-sinking) particulate matter. © 1988 Nature Publishing Group., Cited By (since 1996):108, Oceanography, ,
Author: Karl, Knauer, Martin
Date: 1988-01-01T00:00:00Z

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: Zooplankton fecal pellet fluxes and vertical transport of particulate organic material in the pelagic environment,
Description: Fecal pellet fluxes were determined using a series of multireplicate traps set at 35, 65, 150, 500, 750 and 1500 m in the northeast Pacific.Fecal pellets appear to be important contributors to total carbon fluxes. In near-surface waters (35-150 m), pellet fluxes ranged from 2-3 × 105 pellets m-2 day-1. Minimum pellet fluxes were observed at 500m(̃0.4× 105 pellets m-2day-1). In contrast, the 1500 m pellet flux value increased to approximately 0.8 × 105 pellets m-2 day-1 relative to the 500 m depth, and is probably the result of in situ repackaging. Analyses of pellet content suggest multiple sources of "large" particle input throughout the water column. The implications of this phenomenon are discussed in terms of the detrital rain and ladder of migration theories. © 1981 IRL Press Limited., Cited By (since 1996):51, CODEN: JPLRD, ,
Author: Urrère, Knauer
Date: 1981-01-01T00:00:00Z

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: Vertical distribution, transport, and exchange of carbon in the northeast Pacific Ocean: Evidence for multiple zones of biological activity,
Description: A sediment trap experiment was conducted to investigate the production, decomposition, and transport of organic matter from 0 to 2000 m at a station 100 km northeast of Point Sur, California. Parameters measured included (1) rates of autotrophic production of carbon, (2) vertical depth distributions of total carbon, nitrogen, and living biomass, and (3) downward flux of organic carbon, nitrogen, ATP, RNA, and fecal pellets. Metabolic activity and microbial growth rates (RNA and DNA synthesis) were also estimated in situ, for both the 'suspended' (i.e., samples captured in standard water bottles) and 'sinking' (i.e., samples captured in sediment traps) particles. Daily depth-integrated rates of primary production averaged 564 mg C m-2, of which 10 to 15% was removed from the euphotic zone by sinking, assuming steady-state conditions. The profiles of suspended carbon, nitrogen, C:N ratios, and ATP conformed to previously published concentration-depth profiles from the region. The vertical flux profiles of organic matter, however, revealed two important features that were not evident in the suspended particulate matter profiles. First, there was an obvious mid-water depth increase (i.e., an increase in organic carbon and nitrogen flux with increasing depth) between 700 and 900 m, suggesting horizontal advection or in situ production. Similar flux profiles were also observed for ATP, RNA, and total fecal pellets. Second, the C:N ratios for the sediment trap materials collected at mid-ocean depths (600 to 1200 m) were low compared to values measured for 'suspended' particulate organic materials collected from comparable depths, supporting the in situ production hypothesis. An observed maximum in the rate of RNA and DNA synthesis for microorganisms associated with particles collected at 700 m confirmed that the flux anomalies were the result of in situ microbiological processes rather than horizontal advection. We hypothesize that the in situ activity measured at 700 m is the result of a chemolithotrophic-based carbon production system supported by the presence of reduced inorganic compounds (e.g., NH4+, HS-) found in association with the sinking particles. "New carbon production" (a value equivalent to the increased downward flux of carbon) between 700 and 900m was 15 mg C m-2 d-1, or 2 to 1% of the daily integrated primary production. These regions of intense biological metabolic activity, growth, and organic matter diagenesis may have a profound influence on the oceanic carbon cycle and on the observed steady-state distributions of various non-conservative properties of seawater. © 1984., Cited By (since 1996):51, ,
Author: Karl, Knauer
Date: 1984-01-01T00:00:00Z

Title: Marine snow: Major site of primary production in coastal waters,
Description: Fragile aggregate particles, or "marine snow", were collected by SCUBA from coastal surface waters using trace metal-free techniques, and their primary production (rates of photosynthesis by associated phytoplankton) was determined relative to corresponding water column production. Primary production associated with these particles was found to range from 11 to 58% of total production, indicating that large particles can have an important role as major sites of primary production in the marine environment. Our results suggest that the use of water bottles to collect samples for productivity measurements may not sample large particles adequately in certain conditions, and thus may lead to underestimates of primary production. © 1982 Nature Publishing Group., Cited By (since 1996):10, ,
Author: Knauer, Hebel, Cipriano
Date: 1982-01-01T00:00:00Z

Title: VERTEX manganese transport: Manganese transport through oxygen minima,
Description: Manganese transport through a well-developed oxygen minimum was studied off central Mexico (18°N, 108°W) in October-November 1981 as part of the VERTEX (Vertical Transport and Exchange) research program. Refractory, leachable and dissolved Mn fractions associated with particulates caught in traps set at eight depths (120-1950 m) were analyzed. Particles entering the oxygen minimum had relatively large Mn loads; however, as the particulates sank further into the minimum, total Mn fluxes steadily decreased from 190 nmol m -2 day -1 at 120 m to 36 nmol m -2 day -1 at 400 m. Manganese fluxes then steadily increased in the remaining 800-1950 m, reaching rates of up to 230 nmol m -2 day -1 at 1950 m. Manganese concentrations were also measured in the water column. Dissolved Mn levels < 3.0 nmol kg -1 were consistently observed within the 150-600 m depth interval. In contrast, suspended particulate leachable Mn amounts were especially low at those depths, and never exceeded 0.04 nmol kg -1. The combined water column and particle trap data clearly indicate that Mn is released from particles as they sink through the oxygen minimum. Rate-of-change estimates based on trap flux data yield regeneration rates of up to 0.44 nmol kg -1 yr -1 in the upper oxygen minimum (120-200 m). However, only 30% of the dissolved Mn in the oxygen minimum appears to be from sinking particulate regeneration; the other 70% probably results from continental-slope-release-horizontal-transport processes. Dissolved Mn scavenges back onto particles as oxygen levels begin to increase with depth. Scavenging rates ranging from -0.03 to -0.09 nmol kg -1 yr -1 were observed at depths from 700 to 1950 m. These scavenging rates result in Mn residence times of 16-19 years, and scavenging rate constants on the order of 0.057 yr -1. Manganese removal via scavenging on sinking particles below the oxygen minimum is balanced by Mn released along continental boundaries and transported horizontally via advective-diffusive processes. Manganese appears to be very weakly associated with particulates. Nevertheless, the amounts of Mn involved with sinking biogenic particles are large, and the resulting fluxes are on the same order of magnitude as those necessary to explain the excess Mn accumulating on the sea floor. The overall behavior of Mn observed in this, and other, studies strongly suggests some type of equilibrium occurring between dissolved and particulate phases. This equilibrium appears to shift in direct or indirect response to dissolved oxygen levels. © 1984., Cited By (since 1996):29, Oceanography, ,
Author: Martin, Knauer
Date: 1984-01-01T00:00:00Z

Title: ,
Description: This paper presents current information concerning the formation, make-up, distribution and transport of biogenic particles in the belief that this knowledge will provide greater understanding of the role of these particles in the cycling of trace elements., Oceanography, CODEN: NCSFD, ,
Author: Knauer, Martin
Date: 1983-01-01T00:00:00Z

Title: Trace elements and primary production: Problems, effects and solutions,
Description: The measurement of primary production in the ocean is basic to biological oceanographic processes. Factors which control primary production are varied, but include micronutrients (i. e. , N and P) in sufficient supply, as well as many nanonutrients such as Cu, Mn and Zn. High levels of many of these trace constituents are toxic. Recent studies have shown that ambient concentrations of a number of nanonutrients in sea water are lower by an order of magnitude than previously believed., Cited By (since 1996):1, Oceanography, CODEN: NCSFD, ,
Author: Knauer, Martin
Date: 1983-01-01T00:00:00Z

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: Bacterial chemolithotrophy in the ocean is associated with sinking particles,
Description: The oceanic carbon cycle has traditionally been viewed as a reversible, one step reduction-oxidation reaction (CO 2CH 2O). Principle pathways were thought to involve eukaryotic photoautotrophy and oxygen-dependent bacterial respiration, respectively. However, prokaryotic (cyanobacterial) photoautotrophy is now well documented and has even been proposed as a major carbon pathway 1-6. In a previous study of the mesopelagic zone in the North Pacific Ocean 7, the observed downward fluxes of organic carbon, nitrogen, ATP and RNA suggested production in situ of new particulate organic carbon at 700-900 m. Here we present evidence that this is indeed the case and that it is mediated by bacterial chemolithotrophy. Energy for this process may be in part provided by detrital NH + 4 derived from the downward flux of large particles. © 1984 Nature Publishing Group., Cited By (since 1996):33, Oceanography, ,
Author: Karl, Knauer, Martin, Ward
Date: 1984-01-01T00:00:00Z

Title: Trace metals in large agglomerates (marine snow),
Description: Marine agglomerates were collected by SCUBA from surface waters of Monterey Bay, California and one coastal site 100 km off Point Sur, California using trace metal clean techniques. Concentrations of Al, Fe, Mn, Cu, Ni, Zn, Cd and Pb were measured for both weak acid soluble and refractory metals and compared to suspend material collected in water bottles at the same locations. Gravimetric analysis of agglomerate and surrounding suspended particulate matter indicated that although agglomerates represented <0.1% of total water sample volume (determined photographically), they contained up to 50% of the total particulate dry weight; trace metal concentrations in the agglomerate fraction were also disproportionately high. Agglomerates collected within Monterey Bay contained large quantitites of inorganic material (>40% dry weight), with most of the associated metals contained primarily within the refractory fraction. In contrast, the offshore station agglomerates contained <0.3% inorganic material with metals primarily associated with the weak acid soluble fraction. Both the metal concentrations and leach characteristics of the offshore station suggest that these agglomerates were comprised of an active phytoplankton assemblage highly enriched in Cd. Metal concentrations in the offshore samples in conjunction with agglomerate abundance indicate that agglomerates may be a major transporter of trace metals out of the euphotic zone. © 1986 IRL Press Limited., Cited By (since 1996):14, CODEN: JPLRD, ,
Author: Hebel, Knauer, Martin
Date: 1986-01-01T00:00:00Z

Title: Manganese cycling in northeast Pacific equatorial waters,
Description: Sea water samples collected above, within and below a pronounced oxygen minimum were analyzed for their Mn content. Amounts of dissolved Mn slowly decreased with depth and little, if any, relationship with oxygen was found. In contrast, suspended particulate Mn values increased markedly at the top of the oxygen minimum. Concentrations of weakly leachable Mn probably resulted from microbial oxidation. Labile Mn fluxes, measured with particle interceptor traps at depths of 125, 275, 525 and 900m slowly increased with depth. These rates are the same order of magnitude as those estimated for excess Mn accumulating in open-ocean sediments, which implies that biogenic transport is a major factor in the oceanic cycling of Mn., Cited By (since 1996):5, Oceanography, ,
Author: Martin, Knauer
Date: 1982-01-01T00:00:00Z

Title: VERTEX: carbon cycling in the northeast Pacific,
Description: Particulate organic carbon fluxes were measured with free-floating particle traps at nine locations during VERTEX and related studies. Examination of these data indicated that there was relatively little spatial variability in open ocean fluxes. To obtain mean rates representative of the oligotrophic environment, flux data from six stations were combined and fitted to a normalized power function, F = F 100 (z/100) b; e.g. the open ocean composite C flux in mol m -2 y -1 = 1.53 (z/100 -0.858 with depth z in meters. It is shown that the vertical derivative of particulate fluxes may indicate solute regeneration rates, and accordingly regeneration rates for C, H and N were estimated. Oxygen utilization rates were also estimated under the assumption that 1.5, 1.0 and 0.25 moles of O 2 were used for each mole of N, C and H regenerated. Regeneration ratios of these elements were depth-dependent: i.e. N:C:H:-O 2 = 1.0 N: 6.2 (z/100) 0.130 C: 10.0(z/100) 0.146 H: [1.5 + 6.2 (z/100) 0.130 + 2.5 (z/100) 0.146]-O 2. Comparisons of our rates with those in the literature indicate that trap-derived new productivities in the open Pacific (≈1.5 mol C m -2 y -1) are substantially less than those estimated from oxygen utilization rates in the Sargasso Sea (≈4 mol C m -2 y -1). A hypothesis is presented which attempts to explain this discrepancy on the basis of the lateral transport and decomposition of slow or non-sinking POC in the Sargasso Sea. Data gathered during the VERTEX studies are also used for various global estimates. Open ocean primary productivities are estimated at 130 g C m -2 y -1 which results in a global open ocean productivity of 42 Gt y -1. Organic C removal from the surface of the ocean via particulate sinking (new production) is on the order of 6 Gt y -1. Fifty percent of this C is regenerated in the upper 300 m of the water column. The ratio of new production (measured with traps) to total primary production (measured via 14C) is 0.14. It is concluded that the 14C technique yields reasonable estimates of primary productivity provided that care is taken to prevent heavy metal contamination. © 1987., Cited By (since 1996):671, Oceanography, ,
Author: Martin, Knauer, Karl, Broenkow
Date: 1987-01-01T00:00:00Z

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: Large particle fluxes and the vertical transport of living carbon in the upper 1500 m of the northeast Pacific Ocean,
Description: The distribution, production, and flux of organic carbon were measured at a station in the eastern North Pacific Ocean, off Point Sur, California. Adenosine triphosphate (ATP) and total adenine nucleotide (AT) concentrations were measured to estimate the contribution of biomass (living) carbon to the total particulate organic pools. Two separate classes of particulate materials were considered: (1) 'suspended' or the relatively abundant, low density, fine-grained particles commonly collected in standard water bottles and (2) sediment trap particles, which represent the larger, relatively rare particles not usually sampled (in a statistical sense) when using standard water bottle collections and which require the use of in situ particle traps. The study indicates that living organisms associated with the sedimenting particles can contribute more than 100 times the biomass carbon normally associated with the 'suspended' fraction. The significance of the downward vertical flux of viable organisms associated with large particles may require that we alter our present concepts of the production and cycling of carbon in the open ocean., Cited By (since 1996):9, ,
Author: Fellows, Karl, Knauer
Date: 1981-01-01T00:00:00Z

Title: Fluxes of particulate carbon, nitrogen, and phosphorus in the upper water column of the northeast Pacific,
Description: Concentrations of carbon, nitrogen and phosphorus were determined in particles that passively sank into multi-replicate collectors set at 50, 250, and 700 m in coastal waters, and 75, 575, and 1050 m in the open ocean. Fluxes as high as 36, 4.1, and 0.19 mmoles of C, N, and P m -2 day -1 were observed at 50 m under coastal upwelling conditions; at 700 m, upwelling period fluxes (9.6, 0.9, and, 0.053 mmoles of C, N and P m -2 day -1) exceeded those measured at 50 and 75 m when samplers were set under low productivity surface waters. 210Pb flux estimates were made on coastal trap particulates. The resulting values were close to the expected and suggest that overall flux estimates are representative of those occuring in the environment. Atomic ratios of C:N:P under upwelling conditions were similar to values reported for living plankton (∼180:18:1), while in the open ocean, atomic ratios of C and N in relation to P were markedly higher (400 to 900:30:1). Fecal pellet fluxes were two orders of magnitude higher under upwelling conditions (∼1 to 3 × 10 5m -2 day -1) than those in the open ocean (∼1000 m -2 day -1). Quantities of passively sinking particulate C, N, and P appeared to be equal to or in excess of the amounts required to meet the nutritional needs of the mid-water zooplankton. Rates of change for C, N, and P and inferred rates of oxygen change varied widely in relation to surface productivity. For example, oxygen utilization rates were as high as 790 μll -1 yr -1 in near-surface waters under upwelling conditions and as low as 4.4 μll -1 yr -1 at mid-depth in the open ocean. Our rates of change, determined by direct measurement, generally agree with previously published estimates from mathematical models. © 1979., Cited By (since 1996):182, ,
Author: Knauer, Martin, Bruland
Date: 1979-01-01T00:00:00Z

Title: Lateral transport of Mn in the north-east Pacific Gyre oxygen minimum,
Description: Accurate measurement of the concentration and fluxes of a wide range of dissolved and participate materials in the water column is need to quantify the global cycling of heat, water and chemical constituents 1. An important aspect of any Global Ocean Flux study is the lateral transport of materials at basin or global scales; to study lateral transport, useful tracers of water-mass movements must be identified. Here we report that Mn is rapidly removed (-0.027 μmol m -3 yr -1) from the north-east Pacific Gyre dissolved-Mn maximum onto biogenic particles sinking through the oxygen minimum (500-1,100 m). To support removal, dissolved Mn must be supplied within the oxygen minimum at net advective horizontal transport rates of ̃0.6-0.9 cm s -1. The high affinity of dissolved Mn for particles, together with the readily discernible differences in inshore/offshore dissolved distributions, indicate that Mn Is a chemical tracer with great potential in future studies of large-scale circulation processes in the ocean., Cited By (since 1996):14, ,
Author: Martin, Knauer
Date: 1985-01-01T00:00:00Z

Title: VERTEX manganese transport with CaCO3,
Description: Manganese transport was studied off central California in August and September 1981 as part of the VERTEX (Vertica l Transport and Exchange) research program. Refractory, leachable, and dissolved Mn fractions associated with particles caught in traps set at 11 depths (50 to 2000 m) were analyzed. Through intentional and unintentional CaCO3 dissolution 'experiments', it was learned that the weakly leachable Mn was originally in association with the carbonate phase. Adsorption on surfaces rather than absorption in CaCO3 matrices was indicated by the finding that Mn was not released in proportion to the CaCo3 dissolved, instead it appeared to keep readsorbing to the dissolving surface. Ultimately, Mn went into solution when the particulate CaCO3 was essentially depleted, suggesting that sufficient sites for adsorption were no longer available. Manganese fluxes with CaCO3 were low near the surface (0.1 mg cm-2 ky-1), but increased rapidly in the 50 to 200-m depth interval, and then became more or less constant (1.3 mg cm-2 ky-1 for the remainder of the water column (300 to 2000 m). Rate-of-change estimates indicate that Mn is rapidly scavenged in near-surface waters (-130 ng 1-1 y-1) and slowly regenerated at depth (2.7 ng 1-1 y-1) in our near-shore study area. Residence times for dissolved Mn were estimated at 1.2 y for surface waters and 17 y at depth. The implications of Mn transport with CaCO3 in relation to open-ocean sediment excess Mn are discussed. © 1983., Cited By (since 1996):15, Oceanography, ,
Author: Martin, Knauer
Date: 1983-01-01T00:00:00Z

Title: Manganese cycling in northeast Pacific waters,
Description: Particles trapped at depths of 35, 65, 150, 500, 750 and 1500 m in nearshore Californica waters were analyzed for their associated Mn, Al and C content. Although the concentrations of A1 and Mn indicated that the trapped particulates were primarily alumino-silicates, an additional fraction of originally weakly sorbed Mn (5-30%) was found dissolved in the sediment trap salt solutions. The latter Mn was significantly correlated with the trapped particulate organic C and suggests that passively sinking organic detritus is responsible for the removal of dissolved Mn from the water column. The fluxes resulting from this process are on the order of 35 μg Mn/cm 2 kyr in the mid-water column and thus represent an improtant factor in marine Mn balance schemes. Amounts of dissolved Mn in the surface waters of the study area always exceeded those in the mid-water column in spite of surface Mn removal at a rate of 1200 μg/cm 2 kyr. The only Mn source large enough to balance this removal would appear to be continental weathering, either dissolved riverine Mn or Mn released via the weathering of particulate riverine Mn after its introductive into the marine environment. Residence times based on actual flux and water column measurements were 1.8 years for surface waters and 31 years for the upper 1500 m of the water column. © 1980 Elsevier Scientific Publishing Company., Cited By (since 1996):9, Oceanography, ,
Author: Martin, Knauer
Date: 1980-01-01T00:00:00Z