bluuebunny/crossref_metadata_2025_split huggingface dataset:
Major chemical and mineral components of profundal surface sediments in Minnesota lakes1
Authors: Dean Walter E. , Gorham Eville 
Published: March 2010

Minnesota lakes, characterized primarily on the basis of water chemistry, can also be classified according to the proportions of organic matter, CaCO3, and clastic minerals in their profundal sediments. The northeastern (group 1) lakes are characterized by shallow to very deep basins in Precambrian crystalline rocks, active outlets, and dilute surface waters. Profundal sediments of these lakes contain no sedimentary calcium carbonate and can be subdivided on the basis of organic content. Highly organic sediments of group 1 lakes contain more than 30% organic matter (as loss on ignition), but most group I lake sediments contain less than this.The central group 2 lakes occupy shallow to moderately deep basins in calcareous glacial till, have inactive outlets as a result of net evaporation, contain more concentrated salts than group 1 lakes, and commonly precipitate CaCO3 during the summer. These lakes can be subdivided on the basis of sedimentary CaCO3. Sediments of group 2 lakes with more than 30% organic material contain little or no CaCO3. Southern group 2 lake sediments are characterized by 10–30% CaCO3 and 10–30% organic matter. Sediments of western group 2 lakes contain 30–50% CaCO3 and about twice as much elastic as organic materials. Group 3 lakes occupy shallow depressions in calcareous, sulfur‐rich glacial drift of the arid southwestern prairie region and contain even more concentrated salts than group 2 lakes. Sediments in these lakes are mainly elastic, averaging about 12% organic matter and 20% CaCO3.Variations in water and sediment chemistry, and in sediment mineralogy of these lakes are clearly related to an increase in climatic aridity and aquatic productivity from northeast to southwest. Differences in nature of the underlying glacial drift and in degree of erosion also affect the composition of the lake sediments.
Silicon‐32 specific activities in coastal waters of the world oceans
Authors: Lai D. , Nijampurkar V. N. , Somayajulu B. L. K. , Koide M. , Goldberg E. D. 
Published: March 2010

Measurements of 32Si specific activities in siliceous sponges collected from the coastal waters of the world oceans provide insight into the mixing processes of waters having radically different silicon concentrations. The measured specific activities of in sponges, which should correspond to the values of dissolved silicon (and 32Si) in the coastal waters of the oceans, lie in the range of 4–80 dpm of 32Si kg‒1 SiO2. They are inversely correlated with the concentrations of dissolved silicon in coastal waters from which the samples were collected, and specific activities in the sponges are lower than those measured in surface (0–150 m) ocean waters by direct sampling.In coastal regions there occurs a considerable influx of low specific activity continental waters and high specific activity intermediate and deep waters from the open ocean; the mixing between these various types of water, sampled by the sponge during its life time, determines the 32Si specific activity in sponges. Hence 32Si data in sponges should be useful for determining the budget of silicon in coastal regions.
Influence of sampling method on the chemical composition of water surface film
Authors: Daumas Raoul A. , Laborde Tierre L. , Marty Jean Claude , Saliot Alain 
Published: March 2010

The composition of the surface microlayer was compared at two sites, having different degrees of water pollution, near the northern Mediterranean coast. Harvey (rotating drum device) and Garrett (screen) samplers were used and their effectiveness compared; the enrichment factor shown was greater with the former.Eutrophication due to river runoff and hydrocarbon pollution from refinery effluents may contribute to an increase in the enrichment factor. Differences in chlorophyll, ATP, and pheophytin content between the two sampling methods suggest stratification of the living and inert planktonic material.
Nitrogen fixation in Lake Mendota, Madison, Wisconsin1
Authors: Torrey Marguerite Sherman , Lee G. F. 
Published: March 2010

The effects of various environmental conditions, and of cell composition, heterocyst content, and nitrogen content of algal samples, on fixation of N2 by colonial and filamentous algae in Lake Mendota were investigated.Heterocyst content and temperature were significantly and positively related to acetylene reduction activity (N2 fixation); depth of sample collection was negatively related. Available data do not show whether statistical correlations of acetylene reduction activity with dissolved O2 and pH represent specific effects of O2 and pH on this activity, or simply reflect chemical changes caused by algal photosynthesis.During summer stratification, when surface‐water content of combined inorganic nitrogen was severely depleted, N2 fixation associated with heterocystous blue‐green algae contributed 85% of the total N2 fixed. Bacterial N2 fixation was low compared to that of algae. Despite its small overall contribution to the annual nitrogen budget (38,000 kg of nitrogen; ca. 7% of the total input), N2 fixation is significant in maintaining blue‐green algal nuisances in surface water when non‐N2‐fixing phytoplankton cannot compete effectively.
Manganese in Narragansett Bay1
Authors: Graham William F. , Bender Michael L. , Klinkhammer Gary P. 
Published: March 2010

Concentrations of dissolved manganese and particulate manganese and aluminum were determined in samples from Narragansett Bay, Rhode Island, and its surrounding rivers. Total manganese is approximately conservative, but dissolved and particulate manganese are not. Desorption may occur in the tidal rivers at low salinities. Most riverine manganese is dissolved but manganese in the bay is predominantly particulate, probably due to rapid manganese oxidation at bay water pH.The flux of dissolved manganese into bottom waters was about 2 ± 1 µg cm‒2 d‒1. Concentrations in bottom waters are high relative to surface waters.
The influence of colloidal organic matter on iron and iron‐phosphorus cycling in an acid bog lake1
Authors: Koenings Jeffery P. , Hooper Frank F. 
Published: March 2010

The relationship between iron and phosphorus and the relationship of these elements to colloidal organic matter (COM) was studied in a meromictic acid bog lake by chemical characterization, filtration and in situ dialysis, and in situ experiments with labeled components.Bathophenanthroline (BPN) reactive ferrous iron existed in true solution (dialyzable) in constantly anaerobic monimolimnetic water; in the aerobic epilimnion reactive ferric iron was of colloidal size. Intermediate depths, oxygenated only during spring, contained two forms of ferrous iron reactive to BPN: dialyzable ferrous iron (Fe2+) and colloidal Fe(II) which may have originated through in situ reduction of colloidal reactive ferric iron and may be present as a COM‐Fe2+ complex.The amount of COM influenced the fate of dialyzable Fe2+ (92% of total iron) and dialyzable PO4‐P (85% of total phosphorus) present in anaerobic strata before aeration. Aeration with soluble organic matter present (COM absent) resulted in the formation of colloidal nonreactive ferric iron (84% of total iron) and 65% colloidal PO4‐P, while aeration with 26 mg liter‒1 COM resulted in only 36% colloidal, nonreactive ferric iron and 19% colloidal PO4‐P. COM apparently masks the cationic properties of colloidal ferric iron and retards the formation of nonreactive Fe (III), allowing most of the PO4‐P to remain free in solution and biologically available.
A detailed vertical profile of sterols in the Sargasso Sea1,2
Authors: Gagosian Robert B. 
Published: March 2010

Detailed vertical profiles from the Sargasso Sea show that several sterols, e.g. brassicasterol, appear to be produced and consumed in the upper 1,000 m of the water column. A few, e.g. cholesterol, were found in the entire 4,500‐m water column and may represent more resistant organic compounds.Several mechanisms may introduce sterols into the deep sea. Vertical fluxes of organic particles from the surface appear to control delivery of sterols to the middepth waters of the Sargasso Sea, However, some other process, e.g. physical transport (viz horizontal advection and diffusion), resuspension of sediments, or in situ deep water biological production and consumption controls deep water sterol distribution. Detailed profiles of ancillary data (e.g. POC, total particulate matter, and hydrography) must complement detailed profiles of specific organic compounds to identify the transport mechanisms to the deep sea.
Prey detection in the Chaetognatha: Response to a vibrating probe and experimental determination of attack distance in large aquaria1
Authors: Feigenbaum David , Reeve M. R. 
Published: March 2010

The benthic Spadella schizoptera and the planktonic Sagitta hispida both attacked a fine vibrating glass probe over a broad range of frequencies after being starved for 1–3 days. The response curve for S. schizoptera had a peak at 30 Hz and was similar in shape but far broader than that found by prior workers for Spadella cephaloptera. Sagitta hispida responded differently, with a peak response at 150 Hz and no apparent preference among lower frequencies. It also had a strong (37%) response to nonvibrating lateral sweeps.Neither species would attack the probe at a distance >3 mm. This extremely short attack distance was confirmed, for S. hispida, in a 50‐liter aquarium by a series of feeding experiments, the results from which were applied to a simple model. Sagitta hispida starved for 1 day searched 2,667 mm3 min−1 and had an attack distance of 0.88 mm. These experimental data were used to determine the ability of S. hispida to sustain itself nutritionally in its natural environment.
Determination of microbial activity of estuarine detritus by relative rates of lipid biosynthesis1
Authors: White David C. , Bobbie Ronald J. , Morrison Susan J. , Oosterhof Darlene K. , Taylor Cecile W. , Meeter Duane A. 
Published: March 2010

Microorganisms colonizing allochthonous detritus (live oak leaves) incubated in a north Florida estuary show metabolic activity that can be assayed reproducibly by the incorporation of [32P]H3PO4 and [1‐14C] sodium acetate into the lipids in a 2‐h period without introducing subculture bias. Relatively uncolonized live oak leaves show only about 1% of the biosynthetic capacity of leaves incubated in the estuary for 1 week. Lipid synthesis is proportional to time for at least 2 h and also to detrital mass. Random sampling from pooled portions of many leaves greatly reduces the variance of activities from individual leaves.Rates of phospholipid synthesis paralleled the total extractable ATP and the alkaline phosphatase activity during a 6‐week incubation of live oak leaves in Apalachicola Bay. Rates of 14C incorporation into lipids paralleled the respiratory and the α‐d‐mannosidase
Effects of N:P atomic ratios and nitrate limitation on algal growth, cell composition, and nitrate uptake 1
Authors: Rhee G‐Yull 
Published: March 2010

Scenedesmus sp. was grown in chemostats at a fixed growth rate (µ) in an inorganic medium with nitrogen to phosphorus atomic ratios (N:P) ranging from 5 to 80, to investigate the effect of double nutrient limitation. There was no additive or multiplicative effect of the two nutrient limitations: below the optimal cell N:P of 30, growth was determined solely by N limitation and above 30, by P limitation. Cell N remained constant up to the optimal ratio and increased linearly with N:P above it. The level of cell P was high at low N:P (N‐limited state) but decreased rapidly until N:P approached the optimal and remained constant at a low level at high N:P (P‐limited state).Protein was the major fraction in which excess N accumulated under P limitation. Cell free amino acids were a constant proportion of cell N at all N:P ratios. RNA concentration was the same regardless of N:P, its level being determined by µ independent of the type of limiting nutrients. Cell carbon (C) concentration was higher in the P‐limited than in the N‐limited state. The C fixation rate per unit chlorophyll a, however, was constant under both P‐ and N‐limited states because the variation in chlorophyll a content was similar to that of C.The apparent maximum uptake rate for nitrate (V) in N‐ and P‐limited cultures decreased with increasing cell N or N:P. In N‐limited cultures the half‐saturation constant (Km) also decreased at higher cell N or N:P. The variation of V appeared to be affected by the level of free amino acids.
Continuous culture of marine diatoms under silicon limitation. 3. A model of Si‐limited diatom growth 1
Authors: Davis Curtiss O. , Breitner Norman F. , Harrison Paul J. 
Published: March 2010

A biochemically based model for simulating silicon‐limited diatom growth has been developed in which silicic acid uptake is described by Michaelis‐Menten kinetics. Utilization of silicon within the cell is a function of silicon available in internal pools, while growth is a function of silica in the frustule. Uptake is frequently limited by the rate of silicon utilization within the cell. That rate may be set by the enzymes, or more likely one key enzyme, which regulates the process of frustule formation. Alternatively, some other factor such as light or another nutrient may limit growth, and this in turn may limit silicon utilization within the cell and silicic acid uptake.The model was designed specifically to simulate steady state and transient behavior of a Si‐limited diatom population growing in a chemostat. Comparison of simulations and actual chemostat results indicate that it is a realistic representation of diatom response under these conditions.
Dissolved silica in pore waters of Lakes Ontario, Erie, and Superior sediments
Authors: Nriagu Jerome O. 
Published: March 2010

The distribution of dissolved silica in pore waters from Lakes Ontario, Erie, and Superior sediments is not directly related to the deposition of diatomites from the overlying water. It is proposed that silica concentrations in the pore waters are controlled by dissolution of ferroaluminum silicate, Al1−xFe1−x3+(SiO2)x(OH)6(1−x). The cryptocrystalline complex is formed in the sediments by the reaction of biogenic silica with aluminum and ferric oxyhydroxides or by the hydrolysis of clay minerals.A massive episodic flux of biogenic silica to the sediments follows the crash of diatom blooms. Most of the biogenic silica is however dissolved in the water column or at the sediment‐water interface; a small fraction is fixed permanently in the sediments as the cryptocrystalline complex. Budget calculations show that regeneration of silica from Ontario and Erie sediments far exceeds annual input from external sources.
Natural radon and phosphorus as limnologic tracers: Horizontal and vertical eddy diffusion in Greifensee
Authors: Imboden D. M. , Emerson S. 
Published: March 2010

Two‐dimensional interpretation of monthly measurements of natural radon‐222 at different stations in Greifensee, Switzerland, results in hypolimnetic vertical and horizontal eddy diffusion coefficients (Kz and Kx) of 0.2–0.05 and 1,000–100 cm2 s−1 during the stagnation period in 1975. Application of the one‐dimensional and three‐dimensional horizontally well mixed models to the data from the midlake station produces errors of about a factor of two in the vertical eddy diffusion coefficient. With the hypolimnion mixing information, Kz in the thermocline is estimated to be 0.025 ± 0.015 cm2 s−1 by using dissolved phosphorus as a quasi‐conservative tracer.The eddy diffusion coefficients calculated are in good agreement with those which would be predicted by empirical methods. The results when applied to phosphorus cycling indicate that P reflux from the hypolimnion and thermocline in eutrophic Greifensee is of the same magnitude as external inputs during the months of maximum photosynthesis.
Wind‐driven, steady flows in Lake Superior 1
Authors: Lien S. L. , Hoopes J. A. 
Published: March 2010

The wind‐induced, steady state circulations in Lake Superior were investigated by use of both mathematical and physical models. The mathematical model was developed from the equations of motion, assuming a homogeneous lake, negligible nonlinear accelerations, constant Coriolis force, hydrostatic pressure distribution, negligible horizontal turbulent shear stresses, and constant vertical eddy viscosity. With these assumptions, the equations of motion were solved analytically to give expressions for the velocities in terms of position in lake, wind stress, water surface slopes, depth, vertical eddy viscosity, and bottom condition (i.e. no‐slip or slip). Water surface slopes were obtained from a numerical solution to the vertically integrated equations of motion, expressed in terms of a mass transport stream function and subject to appropriate wind stress and inflow‐outflow conditions. Two‐ and three‐dimensional velocity fields were obtained for uniform and curl wind stress distributions, for constant (average) and actual (variable) depth conditions, and for slip and no‐slip on bottom.Laboratory experiments on the wind‐generated circulation were conducted in a rotating, vertically distorted model of Lake Superior. Surface current patterns were obtained for steady, westerly winds that were constant in magnitude (uniform) over the lake and that had a constant curl (speeds decreased linearly from south to north) over the lake. The laboratory circulation patterns are in reasonable agreement with results from the numerical model.
Phosphorus loadings to lakes and some of their responses. Part 1. A new calculation of phosphorus loading and its application to 13 New York lake 1
Authors: Schaffner W. R. , Oglesby R. T. 
Published: March 2010

Changes are proposed in ways of expressing phosphorus loadings to lakes. A composite species of phosphorus (the sum of soluble reactive, soluble unreactive, and that potentially desorbable from particulate matter) is substituted for the total P used by most investigators. Loadings are expressed as the amount added annually to a volume equivalent to that of the epilimnion, for stratified lakes, and to lake volume for those that are unstratified, rather than to surface area or to total volume regardless of mixing depth. These alterations in calculating loading result in values that more closely approximate the supply of phosphorus available for uptake by the phytoplankton community.Procedures followed in estimating the phosphorus contributed to lakes from various sources are critically discussed, with particular emphasis on that from human populations and runoff from rural lands. Phosphorus loss coefficients are given for the latter. Loadings to 13 New York lakes are calculated. The principal effects of using the composite form of phosphorus and loading to the mixed zone rather than total P and areal loading are to de‐emphasize the effects of agriculture and to emphasize phosphorus input to shallow lakes.
Bioenergetic and developmental response of a mayfly to thermal variation 1
Authors: Sweeney Bernard W. 
Published: March 2010

Egg development, growth, and emergence of Isonychia bicolor were observed in White Clay Creek (Pennsylvania) at ambient temperatures and in fluctuating experimental regimes with diel minima ranging from 12°–12.9°C and maxima between 12° and 20.1°C. Development rate of both eggs and nymphs was correlated positively with increased magnitude of the diel temperature pulse. Adult metamorphosis was most successful in regimes with diel maxima >16°C.Subimago body size and fecundity for winter generation females were about double those for the summer generation. Reducing spring and summer water temperatures lowered the fecundity of winter and summer subimagoes.Weight‐specific respiration rates of nymphs measured at 1.4 constant temperatures (range, 1°–21°C) increased with temperature but were inversely related to body size at a given temperature. Metabolic response to short term (1 h) changes in temperature was immediate; thermal acclimation or compensation was not observed.Energy budgets were calculated for male and female nymphs reared in various thermal regimes. Growth rates, net growth efficiencies, and production:respiration ratios of female nymphs were about twice those of males at all temperatures. Overall net growth efficiencies for I. bicolor averaged 44.16% and P:R ratios 0.84 for the combined sexes.
Chemistry of small Norwegian lakes, with special reference to acid precipitation 1
Authors: Wright Richard F. , Henriksen Arne 
Published: March 2010

The concentrations of major ions were determined in 155 representative, small, pristine lakes in southern Norway. The chemistry of these lakes appears to be governed by three factors: atmospheric inputs of seawater salts supply most of the Cl and Na; acid precipitation supplies most of the SO4 and H+; and terrestrial inputs of chemical weathering products account for most of the Ca, Mg, and HCO3.The interaction of acid precipitation and geologic environment largely explains pH levels in these lakes. Lakes in granitic terrains have low concentrations of major ions, low buffer capacities, and are often acidic (pH < 5) when located in areas subject to acid precipitation. Sulfate is the major anion. Lakes in granitic terrains that do not receive highly acidic precipitation have pH levels >5.5, and bicarbonate is the major anion.
Specific blue‐green algal carotenoids in sediments of Esthwaite Water
Authors: Griffiths Mary 
Published: March 2010

Two cores from Esthwaite Water have been analyzed for oscillaxanthin, derived from Oscillatoria alone, and myxoxanthophyll found only in blue‐green algae. Myxoxanthophyll profiles are similar for the two cores with maxima at 6–7 cm and 14–16 cm and low values in the top 5 cm and below 17–19 cm. Oscillaxanthin follows the same general pattern but without pronounced maxima. Such profiles can be used to indicate the appearance of Oscillatoria and other blue‐green algae in a lake, and indirectly, the onset of eutrophication.Raw data for the blue‐green algae present in the lake between 1948 and 1976 have been analyzed. When the years of maximal algal counts in the lake are correlated with the depths of myxoxanthophyll maxima in the sediment, an annual sedimentation rate for the top 15 cm of 0.6 cm · yr−1 is obtained, which agrees quite well with results by other methods.