A model for inorganic control of phosphate concentrations in river waters

Fox, Lewis E.

doi:10.1016/0016-7037(89)90393-1

Cited by 114 publications

(69 citation statements)

References 65 publications

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“…6, only 10 % of the added label could not be accounted for as uptake into particulate fractions. This loss may either be a natural process converting orthophosphate to dissolved, but biologically unavailable forms such as adsorption to humic substances, complexation with Fe or other chemical processes (Cembella et al 1984b, Froelich, 1988, Fox, 1989, DeHaan & Salonen, 1990, or an artifact due to breakage of cells on the filters so that 10 %of the orthophosphate taken up was lost to the filtrate.…”

Section: Discussionmentioning

confidence: 99%

“…This is also inconsistent with the estimated K+Sn values for bacterial orthophosphate uptake which averaged 12 nmol 1-' in the brackish layer, although this discrepancy may possibly be attributed to a combination of very small K-values for bacterial uptake in combination with the large standard errors in estimation of K+S,. An overestimation of biologically available orthophosphate by chemical methods may potentially be caused either by measurement of biologically unavailable complexes (De Haan & Salonen 1990, Fox 1989, Froelich 1988 or by hydrolysis of unstable DOP-substances caused by the chemicals added for SRP determination (discussion in Karl & Tien 1992 and references therein). If our conclusion that the K+Sn values obtained for the bacterial size fraction in isotope dilution experiments contains a halfsaturation constant of ca 11 nmol I-', estimation of biologically available orthophosphate directly from isotope dilution experiments would have a lower limit of the same order of magnitude due to the required precision in the data and the present lack of knowledge of the value of K for orthophosphate uptake by natural bacterial populations.…”

Section: Discussionmentioning

confidence: 99%

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Phosphorus cycling and algal-bacterial competition in Sandsfjord, western Norway

Thingstad¹,

Skjoldal²,

Bohne³

1993

Mar. Ecol. Prog. Ser.

247

164

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Microbial phosphorus-cycling, with particular emphasis on algal/bacterial competition, was studied in depth profiles through the halocline separating a brackish top layer, rich in nitrate and poor in phosphate, from the underlying coastal water, poor in both nitrate and phosphate, in the Sandsfjord area, western Norway. At 2 stations along the axis of natural freshwater outflow, physiological P-deficiency of algae and bacteria in the brackish layer was inferred from rapid luxury consumption of added PO: -by organisms in size fractions > l pm and 1-0.2 pm, respectively. In a branch of the fjord without natural freshwater outlets, luxury consumption in the brackish layer was less, and without a clear difference between the 2 water layers. High luxury consumption coincided with short (< 30 min) turnover times for ~0 2 -a n d strong bacterial dominance of 32P0,"--uptake, suggesting bacterial superiority as competitors during P-limiting conditions. Estimation of P-specific maximum uptake rate and affinity for PO:--uptake from isotope dilution experiments indicated bacterial superiority at low and algal superiority at high concentrations. Although most of the 32P hydrolyzed from added y -~T 3 2 P was initially liberated as free 32P04, partitioning of incorporated 32P between size fractions > l pm and 1-0.2 pm was found to depend on whether label was added as y -~T " P or as 3 2~0 , , -, indicating that coupling of uptake to hydrolysis by cell-bound enzymes could modify the outcome of algalbacterial phosphorus competition. Disappearance rate of "P from the 1-0.2 pm size fraction following initial labeling and a subsequent cold chase with PO:-, was used to estimate the flow-rate of phosphorus through the microbial food web. Combined with measured kinetic constants for PO: -uptake. alkaline phosphatases and 5'nucleotidases, a coherent flow-scheme could only be obtained assuming very low (< 1 nmol I-') concentrations of PO;'-and nucleotides. Chemically measured concentrations of dissolved organic phosphorus (DOP) more than 2 orders of magnitude above the estimated nucleotide level and with an estimated turnover time of ca 500 h, are consistent with the view that this large Preservoir consists mainly of slowly hydrolyzable polymers.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Phosphorus cycling and algal-bacterial competition in Sandsfjord, western Norway

Thingstad¹,

Skjoldal²,

Bohne³

1993

Mar. Ecol. Prog. Ser.

247

164

View full text Add to dashboard Cite

show abstract

“…Phosphorous is the limiting nutrient for the spring bloom, and is supplied to the surface waters via similar pathways as iron. Phosphorus and iron have linked hydrogeochemical pathways, especially in the suspended phase; P is transported adsorbed on or co-precipitated with Fe oxyhydroxides in river systems (Fox, 1989;Pokrovsky and Schott, 2002). In previous studies, the removal of dissolved P and Fe during estuarine aggregation has shown to be coincidental; Fe oxyhydroxides formed by aggregation at increasing salinity incorporate phosphate, which drastically diminish the dissolved P concentration through a salinity gradient (Gunnars et al, 2002).…”

Section: Biological Processes In the Euphotic Zone And Sinksmentioning

confidence: 99%

Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

Gelting

Breitbarth²,

Stolpe³

et al. 2010

Biogeosciences

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“…It has been used successfully in other geochemical studies involving the interactions of POa3-with particles (Fox 1989). Although one marine study has shown that sodium azide is not completely effective at stopping all biological activity (Harvey 1988), it was effective at stopping both bacterial and phytoplankton production in my study.…”

Section: Discussionmentioning

confidence: 83%

Phosphate uptake along a coastal plain estuary

Lebo

1990

Limnology & Oceanography

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Biotic PO,'-uptake rates were measured along the Delaware estuary to examine seasonal and spatial patterns of variation. Uptake was highest (40-90 nmol liter-' h-l) in summer and lowest (< 10 nmol liter-' h-l) in winter. The highest rates of PO,"-uptake were measured in the tidal river and the lower bay (salinity > 150/w) where primary productivity is high. Between the river and the lower bay, the concentration of suspended sediment is high, and PO,j-uptake was reduced (~5 nmol liter-' h-l) at all times of the year. Partitioning of uptake by size revealed that both bacteria and phytoplankton are important in the uptake of POd3-throughout the estuary. The proportion ofuptake by bacteria, however, changed spatially. In the tidal river where anthropogenic inuuts are hiah, bacteria dominated PO," uptake and accounted for up to 70% of the total. Within the salinity gradient of the estuary, the proportion of bacterial uptake was much lower, with bacteria accounting for only 15-25% of POd3-uptake. The competition between bacteria and phytoplankton for PO,'-was affected by anthropogenic inputs into the tidal river.The availability of phosphorus in natural systems significantly affects biological production. In many aquatic systems, the rate of primary production and the accumulation of phytoplankton biomass are influenced by the concentration and flux of P (Jaworski 198 1;Schindler 1985). In estuaries, the rate of P cycling has been found to vary considerably with the turnover time of POd3-ranging from minutes (Taft et al. 1975) to days (Friebele et al. 1978;Berman 1983).The biological removal of POd3-in estuaries includes uptake by both phytoplankton and bacteria. Although classical ecological schemes regard bacteria as remineralizers of organic matter, research over the past 30 yr has revealed that bacteria account for a substantial proportion of POd3-uptake in natural systems. The importance of bacteria in the uptake of POd3-was first demonstrated in lakes where Rigler r Present address: Div. Environ. Stud., Univ. California, Davis 95616.

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A model for inorganic control of phosphate concentrations in river waters

Cited by 114 publications

References 65 publications

Phosphorus cycling and algal-bacterial competition in Sandsfjord, western Norway

Phosphorus cycling and algal-bacterial competition in Sandsfjord, western Norway

Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

Phosphate uptake along a coastal plain estuary

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