bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass transfer to and from small particles in the sea1,2
Authors: Csanady G. T. 
Published: April 2010

Slowly sinking particles exchange mass with their liquid environment if dissolution processes within the particles maintain a surface concentration excess or deficiency χ0 of a soluble substance above background. If the exchange is controlled by diffusion in the liquid phase, the total mass loss is proportional to χ0, diffusivity D, and particle diameter d. If advection associated with the sinking of the particle dominates over diffusion, the exchange rate varies as χ0D⅔d2 and is weakly affected by particle density and fluid viscosity. This is the case for spherical particles of a diameter 70 µm.The resulting dissolution rate per unit depth of sinking is constant for large particles, but increases sharply once the particles are small and slow enough for mass exchange to be controlled by diffusion. With oxygen supply supposed the rate‐controlling process of particle decomposition, a realistic depth of decomposition of order 1 km is calculated for 200‐µm‐diameter spherical particles. The generation of an oxygen minimum at such depths then requires the production near the sea surface of sufficiently large organic particles in sufficient numbers.
Reconciling measured and predicted fluxes of oxygen across the deep sea sediment‐water interface1
Authors: Reimers Clare E. , Smith K. L. 
Published: April 2010

Rates of sediment community oxygen consumption determined in situ are compared to fluxes predicted from oxygen microelectrode gradients measured in cores from ∼3,750‐m water depth in the eastern North Pacific. Oxygen concentrations decrease exponentially over > 1.5 cm and suggest that organic matter in the sediments is degraded most rapidly immediately below the sediment‐water interface.Molecular diffusion of oxygen across the interface is modeled as an “internal regime” and can account for nearly all the directly measured in situ flux, 0.20±0.02 µmol cm−2 d−1. This differs from published accounts of nearshore marine environments, where activity of bottom‐dwelling macrofauna or bubble ebullition enhances benthic fluxes of dissolved nutrients or gases 2–4 times. Millimeter depth‐scale profiles of porosity, organic C, carbonate C, and bacterial abundance are reported to provide additional constraints on interface processes, including the relative effects of organic matter degradation and bioturbation. The highest organic C, bacterial, and porosity values are in the uppermost sediments (0–0.2 cm). Within the stratum 0–1 cm, porewater flux ratios of oxygen to nitrate support a model of exchange by diffusion leading to organic matter oxidation and nitrification according to Redfield stoichiometry. Below the oxygen reduction zone, changes in the porewater concentrations of NO3−, Mn2+, Fe2+, NH4+, and alkalinity indicate that anaerobic respiration reactions using NO3−, MnO2, Fe2O3, and SO42− as electron acceptors complete the early oxidation of organic matter at this site.
Redox state of iron in the offshore waters of Peru1
Authors: Hong Huasheng , Kester Dana R. 
Published: April 2010

The total concentration and redox state of iron were examined along a transect across the continental shelf off the Peruvian coast during January 1984. Total and dissolved iron (0.4‐µm filter) were measured by the Co‐APDC coprecipitation method. Fe(II) was measured by a preconcentration step with 8‐hydroxyquinoline bonded to silica as the stationary phase, followed by elution and the ferrozine method.Up to 40 nmol kg−1 of Fe(II) was detected in the bottom water at 5–10 km offshore and decreased markedly upward in the water column and with distance offshore. A good correlation between the distribution of Fe(II) and nitrite in the bottom water indicated a common source from the shelf sediments. Elevated Fe(II) concentrations near the sea surface and a diel change were probably due to photochemical reactions involving iron.Total iron levels were >300–500 nmol kg−1 in the surface and the bottom water at 5–6 km offshore. About 80–90% of the iron was in the particulate form, indicating a substantial input of iron from continental dust and from the sediments on the shelf. The total iron level decreased considerably within 35 km of the coastline and the iron seemed to be trapped on the shelf.
Sources of nitrogen for primary production in warm‐core rings 79‐E and 81‐D1
Authors: McCarthy James J. , Nevins John L. 
Published: April 2010

Profound changes in concentrations of phytoplankton biomass and rates of primary production in warm‐core Gulf Stream rings can occur, apparently in response to nutrient enrichment, within a few months after a ring separates from the Gulf Stream.In Ring 81‐D at 3 months of age the dependence on NO3− was 2½–3 times as high as in the northern Sargasso Sea and in Ring 79‐E shortly after formation. The NO3− gradient at the base of the mixed layer in the new Ring 79‐E was 0.09 µmol kg−1 m−1, whereas that for the older Ring 81‐D was 0.30. The increase in proximity of NO3− to the mixed layer may be a general phenomenon associated with the aging process of warm‐core rings. The increase in this gradient enhances the potential for episodic bursts of production in warm‐core rings in response to turbulent mixing at the base of the mixed layer.Following an interaction with the Gulf Stream and a gale force storm, the mixed layer of Ring 81‐D cooled and its NO3− content increased. In response to increased availability of NO3−, both the rate of phytoplankton utilization of NO3− and the rate of primary production increased. Integrated rates for NO3− uptake in the mixed layer increased sevenfold (from 28 to 195 µmol m−2 h−1).
Calcite precipitation in Lake Constance: Chemical equilibrium, sedimentation, and nucleation by algae1
Authors: Stabel H.‐H. 
Published: April 2010

Seasonal shifts in calcium carbonate solution equilibria in the limnetic zone of Lake Constance were documented between 1981 and 1983. Except during mixing times, lake water was supersaturated with respect to calcite; epilimnetic supersaturation maxima were closely related to changes in pH. Sedimentation of calcium from the lower boundary of the euphotic zone to the lake bottom was also assessed. The daily sedimentation flux for calcium during the season varied over three orders of magnitude. Differences in the calcium content of sediments trapped at various depths were insignificant. Sedimentation rates of titanium were used as tracers for the fluxes of calcium bound on allochthonous clastic material. Lacustrine calcite precipitation (39–49% of the total sedimentation rate) was obtained by subtracting fluxes of allochthonous Ca from the rates of total Ca sedimentation.Calcium supersaturation maxima were not in phase seasonally with maximum fluxes of autochthonous Ca. Instead, calcite precipitation was associated with the occurrence of Stephanodiscus hantzschii, Fragilaria crotonensis, Asterionella formosa, Chlorella sp., Pandorina morum, and Mougeotia thylespora, indicating that calcite formation was triggered by heterogeneous nucleation induced by certain algal species.
Growth, mortality, and secondary production of the copepod Acartia tranteri in Westemport Bay, Australia1
Authors: Kimmerer W. J. , McKinnon A. D. 
Published: April 2010

We measured the growth rate of Acartia tranteri and related variables in Westernport Bay, Australia, on 19 occasions in 1982–1984. Acartia tranteri is numerically dominant in the bay zooplankton, with a mean abundance of all life stages of 12,000 m−3. Growth rates, measured by an incubation method, varied between 0.025 and 0.26 d−1 with a time‐weighted mean of 0.11 d and chlorophyll concentrations together explained 50% of the variance in growth rate, which was usually food limited.Annual secondary production of A. tranteri was 130 mg C m−3, < 1% of phytoplankton primary production. Zooplankton production is a minor constituent of the energy budget of the bay, compared to benthic production.Mortality rates, estimated from stage abundances and development times, were very low except in early naupliar stages. Median adult longevity was 26 d when water temperature was <17°C, and only 4 d when temperature was >20°C. The low mortality and high longevity are consistent with the observed low abundances of planktonic predators and with the low consumption rates of Acartia by planktivorous fish in the bay.
Oceanic stratified euphotic zone as elucidated by 234Th: 238U disequilibria1
Authors: Coale Kenneth H. , Bruland Kenneth W. 
Published: April 2010

Profiles of dissolved and particulate 234Th were determined at the VERTEX 2 and 3 stations off Manzanillo, Mexico, and at the VERTEX 4 station about 900 km north of Hawaii. By modeling the disequilibria between 234Th and 238U in the dissolved and particulate form, estimates of scavenging rates for Th from the dissolved to particulate phases, particle residence times, and the flux of Th via particle removal can be obtained. 234Th:238U activity ratio profiles indicate that the euphotic zone can be separated into two layers: An upper oligotrophic layer characterized by low new production values, low net scavenging, and long dissolved 234Th residence times; and a subsurface eutrophic layer with higher new production values, more intense scavenging, and shorter dissolved 234Th residence times.New production, rather than total primary production may determine net scavenging rates of reactive elements from oceanic surface waters. These results contribute to the emerging descriptions of the layered structure of oligotrophic euphotic zones and support the notion that this may be a general and ubiquitous feature of global stratified oligotrophic regimes. These layered systems can be structured not only in biological and nutrient parameters, but also in terms of the rates of chemical scavenging and elemental transport.
Microbial oxidation of manganese in a North Carolina estuary1
Authors: Sunda William G. , Huntsman Susan A. 
Published: April 2010

Experiments were conducted with 54Mn(II) to determine the kinetics of particulate manganese formation in seawater from the lower Newport River estuary, North Carolina. Dissolved Mn was rapidly converted into particles at constant rates that ranged from 0.36 to 6.2% h−1 (0.62–3.5 nmol liter−1 h−1), yielding turnover times of the dissolved manganese pool of 0.7–11 d. Dissolved Mn turnover rates increased with temperature (Q10 = 2) up to a maximum at 25°–35°C and also increased with the ratio of particulate to dissolved Mn. These two factors explained most of the variation in the observed turnover rates.Sample deoxygenation reduced the formation of particulate 54Mn by 94% and virtually all the particulate 54Mn formed in natural oxygen‐containing samples could be dissolved by 10 µM ascorbic acid, a strong reducing agent. These results indicated that the formation of particulate 54Mn resulted primarily from the oxidation of Mn(II) to manganese oxides (MnOx). The oxidation rates, however, were much too rapid to be accounted for by abiotic mechanisms, and the rate was reduced by 97% following heat sterilization of the seawater. In addition, the rates conformed to the Michaelis‐Menten enzyme kinetics model with Vmax equal to 1.2 × 10−8 mol liter−1 h−1 and Ks equal to 1.9 × 10−7 M. These findings provide strong evidence that oxidation of Mn in the estuarine samples is microbially catalyzed. This catalysis appears to be instrumental in the rapid redox cycling of Mn and in the scavenging of dissolved Mn onto particles in aquatic systems.
Biomass and production of small and large free‐living and attached bacteria in Lake Constance1
Authors: Simon Meinhard 
Published: April 2010

Cell numbers, biomass, and secondary production of small (0.2–1 µm) and large (1.0–3.0 µm) free‐living and attached bacteria were studied in Lake Constance. Biomass as well as production rates exhibited large fluctuations vertically and seasonally. When averaged over a year, small free‐living bacteria were most important for recycling of organic matter since they comprised 77% of total cell numbers and 66% of bacterial secondary production. Large free‐living bacteria contained roughly half of the total bacterial biomass because of their relatively larger cell size. Although attached bacteria usually were of minor importance, they occasionally comprised about half of total bacterial production. During the phytoplankton spring bloom when bacterial production reached its maximum, 60–80% of all free‐living bacteria were active as shown by autoradiography. During that period a high portion of detrital particles was colonized by metabolically active cells.The data suggest that biomass, cell size, and production of free‐living bacteria are controlled by substrate input and grazing of either heterotrophic microflagellates or crustacean zooplankton. In contrast, biomass and production of attached bacteria appear to be predominantly controlled by substrate input of readily decomposable particulate organic matter.
Quantitative in vivo absorption spectra of phytoplankton: Detrital absorption and comparison with fluorescence excitation spectra1
Authors: Maske Helmut , Haardt Hauke 
Published: April 2010

Spectral absorption of phytoplankton from cultures and natural samples was measured on filters with various optical setups including collimated and diffuse irradiation and measurements of wetted filters within an integrating sphere. In suspensions within an integrating sphere, specific absorption coefficients for laboratory cultures varied by a factor of only two.Measurements on filters yielded values dependent on filter load. Specific absorption coefficients derived from measurements of sample filters were considerably higher than values obtained from suspensions in an integrating sphere due to increased diffuseness of irradiance and to pathlength amplification by filter‐particle and particle‐particle interactions. Measured absorption of phytoplankton in the blue can be increased greatly by absorption of detritus, evident from absorption spectra of depigmented samples on filter. After subtracting detrital absorption, absorption spectra of phytoplankton are qualitatively similar to the corresponding quantum‐corrected fluorescence excitation spectra. The detritus‐corrected ratio of absorption at 440 vs. 675 nm shows average values between 1 and 1.5.Comparison with published values shows that specific in vivo absorption coefficients of phytoplankton are mostly overestimated as a result of the methodology applied. In the blue region of the spectrum, overestimation of phytoplankton absorption in field samples is possible if detrital absorption is neglected.
Experimental study of size‐selective phytoplankton grazing by a filter‐feeding cichlid and the cichlid's effects on plankton community structure1
Authors: Drenner Ray W. , Hambright K. David , Vinyard Gary L. , Gophen Moshe , Pollingher Utsa 
Published: April 2010

In laboratory experiments, feeding rates of small (40–61‐mm standard length, SL) and large (98–143‐mm SL) Galilee Saint Peter’s fish (Tilapia galilaea) on phytoplankton and zooplankton increased as a function of particle size, leveling off when particle size exceeded 6–10 µm. Fish had high feeding rates on zooplankton, the large dinoflagellates Peridinium cinctum and Peridinium elpatiewsky, and a few nanoplankton, but most species of nanoplankton were consumed at lower rates.To examine community‐level effects of the fish, we conducted two 7‐d outdoor tank experiments with six fish‐density treatments ranging from 0 to 400 g m−3. Crustaceans, rotifers, and Peridinium spp. declined as functions of fish density, but nanoplankton abundance was highest at intermediate fish densities. Suppression of Peridinium spp. by fish resulted in a reduction of total chlorophyll and gross primary production.
The seasonal variation of dimethyl sulfide and dimethylsulfoniopropionate concentrations in nearshore waters1
Authors: Turner Suzanne M. , Malin Gillian , Liss Peter S. , Harbour Derek S. , Holligan Patrick M. 
Published: April 2010

Concentrations of biogenic dimethyl sulfide (DMS) in seawater around mainland Britain in winter and summer (1985) ranged from 1 to 1,100 ng S (DMS) liter−1. The mean winter DMS concentration was 4 ng S (DMS) liter−1 compared with the mean summer concentration of 220. Analyses of phytoplankton species composition in summer indicate that the main sources of DMS were coccolithophores, various dinoflagellates including the bloom species Gyrodinium aureolum, and certain unidentified taxa of small flagellates. Concentrations of dimethylsulfoniopropionate (DMSP), the precursor of DMS, were measured in 53 of the summer samples, and its mean concentration was about an order of magnitude greater than that of DMS. Particulate (>0.2 µm) and dissolved fractions of DMSP were operationally resolved, with the latter showing the stronger correlation with DMS.Preliminary estimates for the areal and temporal average flux of sulfur (DMS) from the North Sea to the atmosphere during summer are of the order of 103 µg S m−2 d−1, a 60‐fold increase over winter flux. Biogenic emission in summer is equivalent to about 16% of the spatially averaged anthropogenic emission from Europe.
Methylamine uptake by zooxanthellae‐invertebrate symbioses: Insights into host ammonium environment and nutrition
Authors: D'Elia Christopher F. , Cook Clayton B. 
Published: April 2010

Cnidarians with endosymbiotic algae (=zooxanthellae) take up dissolved inorganic nutrients from seawater, but neither the physiological mechanisms nor the effect of host nutrition on transport kinetics is known. We used the NH4+ analogue [14C]methylamine ([14C]MA) to examine these aspects of NH4+ uptake by a sea anemone (Aiptasia pallida) and a coral (Madracis decactis).Both intact symbioses and isolated zooxanthellae took up [14C]MA. In anemones, uptake rates per algal cell increased with time after feeding. Uptake rates for isolates from hosts unfed for 7– 10 d were linear for at least 200 min, slightly light‐dependent, and conformed to Michaelis‐Menten kinetics (Ks = 68 µM; V = 3.8 mol 10−18 cell−1 s−1). Isolates from well‐fed hosts took up [14C]MA much less rapidly at all concentrations tested and did not exhibit saturable uptake kinetics. NH4+ competitively inhibited [14C]MA uptake by isolated algae (inhibition constant = 4.0 µM) and reduced [14C]MA uptake by intact symbiotic anemones. We hypothesize that [14C]MA (and by analogy NH4+) uptake occurs by a “depletion‐diffusion” mechanism in intact symbiotic anemones with zooxanthellae maintaining very low intracellular [14C]MA and NH4+ concentrations in host tissue and that [14C]MA uptake kinetics will be useful in evaluating the nutritional status of corals and similar symbiotic associations under field conditions.
Interannual variation in seasonal predation: Its origin and ecological importance1
Authors: Hairston Nelson G. 
Published: April 2010

Between‐year variation in the springtime mortality of the copepod Diaptomus sanguineus is quantified using 8 yr of data from a single population in Bullhead Pond, Rhode Island. The mortality is ascribed to increased fish feeding activity when the water warms. The timing of the onset of predation and its intensity are quantified using the seasonal dynamics of adult copepod sex ratio. Females are more vulnerable to predation than males, and the slope of a plot of sex ratio vs. time is >0 when the fish begin to influence the copepod population. The magnitude of the slope is an index of predation intensity.The annual onset of predation and its intensity are each significantly correlated with fish density, and fish density is a function of pond volume. Pond volume fluctuates between years, driving the dynamics of this predator‐prey interaction. Annual variation in pond volume is related to groundwater level, which in turn is related to annual rainfall. Groundwater and rainfall records from the USGS and NOAA permit estimates of the extent of variation in springtime copepod mortality over a 38–45‐yr period.
Defensive spines: Inverse relationship between coefficients of variation and size1
Authors: Kerfoot W. Charles 
Published: April 2010

Coefficients of variation for spine lengths are not constant over a range of mean values, but show an inverse relationship with sample means. The nearly hyperbolic relationship is evident in selection experiments, in seasonal samples from a single lake, and in widely dispersed geographic samples. The observed inverse relationship could indicate an interesting developmental property (e.g. that smaller, rudimentary spines are more variable than larger functional ones) or could reflect one of several possible statistical artifacts or properties.Detailed examination of Bosmina suggests that the strong inverse trend arises from a combination of biological and statistical properties; it is not an artifact of measurement error, although measurement error contributes to inflation of small values. Small spines are inherently more variable than longer spines, and the latter have more uniform component parts. Moreover, there are several alternative arrangements of components that sum to the same length and hence that achieve nearly equivalent fitness value. These alternative arrangements lower part‐whole correlations within the population.The two statistical properties that contribute to observed trends include a version of the central limit theorem and measurement error. The percentage variation of a character which is the sum of a number of randomly varying parts will be considerably less (roughly as the inverse square root of the number of parts) than the mean percentage variation of the parts themselves. Thus a statistical property of large numbers contributes to the observed inverse trend. In addition, coefficients of variation as fractions are especially sensitive to measurement error, so that precise measurements are recommended for small defensive spines.
Saprophytic Mycotic Infections of the Nose and Paranasal Sinuses
Authors: Kameswaran Mohan , Raghunandhan S 
Published: April 2010

AbstractThe kingdom of fungi is ubiquitous and omnipresent, having prevailed over the tides of time, over numerous decades by adapting to various methods of survival in the susceptible host including humans. Saprophytic fungi derive nutrition from dead and decaying organic matter, with the capacity to flare up in virulence, provided the right opportunity especially when the host immunity is compromised (as in prolonged steroid therapy, diabetes, HIV infection, tissue transplant recipients) or if there is a breech in a vital barrier permitting deeper tissue penetration (postsurgical or post-traumatic). Hence, knowledge about the saprophytic fungal elements dwelling within the nose and paranasal sinuses is paramount for Otolaryngologists worldwide, in order to accurately diagnose and effeciently manage such intriguing cases. This article provides a broad overview of the various opportunistic fungi in rhinology, and highlights the principles of diagnosis and protocols in management.
Rhinocerebral Mycosis: Combined Modality Protocol
Authors: Kalsotra Gopika 
Published: April 2010

AbstractRhinocerebral mycosis is an invasive fungal infection which occurs primarily in the paranasal sinuses and progresses to involve the brain and/or the orbit. It is commonly seen in immunocompromised individuals and can be most effectively treated if diagnosed early, when it is limited to the nasal cavity and the paranasal sinuses. Even though it is acceptable that surgical debridement in combination with antifungal therapy can lead to high rate of cure, the surgical approach for intracranial extension is still a subject of debate. Twenty-four cases of rhinocerebral mycosis managed at our institute are discussed, regarding presenting complaints and management.