Factors controlling the concentrations of soluble phosphorus in the Mississippi estuary1

Fox, Lewis E.; Sager, Shawn L.; Wofsy, Steven C.

doi:10.4319/lo.1985.30.4.0826

Cited by 67 publications

(45 citation statements)

References 20 publications

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“…4). Such bell-shaped DIP profiles have already been noted in other estuaries (Kaul and Froelich 1984;Fox et al 1985;Forsgren et al 1996) and indicate a DIP release along the salinity gradient. This implies global processes of water particle interactions in the salinity gradient.…”

Section: Discussionmentioning

confidence: 74%

The dynamics of phosphorus in turbid estuarine systems: Example of the Gironde estuary (France)

Deborde

Anschutz

Chaillou

et al. 2007

Limnology & Oceanography

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Suspended particles and surface waters were collected in the Gironde estuary (southwestern France) along the salinity gradient. Dissolved inorganic phosphorus (DIP) was analyzed in the filtered surface waters. The suspended particles were sequentially leached to determine five fractions of phosphorus: exchangeable or loosely sorbed P, reactive Fe-bound P, refractory Fe oxide-bound P, P associated with apatite and carbonates, and organic P. Experiments were conducted to determine the effects of temperature, salinity, and DIP concentration on phosphorus sorption/desorption processes. The concentration and distribution of particulate phosphorus was homogeneous along the salinity gradient of the estuary, whereas it was variable in time and space in the freshwater part. DIP showed a rapid desorption of loosely sorbed P at low salinities. Desorption depended on suspended particle concentration, but not on DIP concentration. At high suspended particle concentrations, some exchangeable P remained linked to particles, until suspended particle concentration decreased downstream of the estuary. This delayed desorption of bioavailable P occurs in waters in which the penetration of light is sufficient to support photosynthesis and probably plays a major role in primary production at high salinities. Mineralization of organic phosphorus also releases available phosphorus, but this process is slow relative to the water residence time in the estuary. The budget of DIP, the loss of particulate P from the organic fraction, and the water residence time suggest that the dynamics of P in the Gironde estuary is well explained by the two processes of P release from particles to waters without P uptake.

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Section: Discussionmentioning

confidence: 74%

The dynamics of phosphorus in turbid estuarine systems: Example of the Gironde estuary (France)

Deborde

Anschutz

Chaillou

et al. 2007

Limnology & Oceanography

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“…Within the freshwater portion of the river, labile-P released from pore waters is likely to be incorporated into the mineral matrix of suspended particulate Fe(III) oxides in surface waters. Low light conditions in the turbid lower Mississippi River limit the primary producer uptake of P (Fox et al 1985). The transfer of P released from the Fe and labile phases to the organic P phase could occur through uptake by heterotrophic bacteria, but this pathway does not appear to have a significant effect on the org-P content in sediments in this physically dominated system.…”

mentioning

confidence: 86%

“…Third, the Mississippi River estuary has been shown to have a ''phosphorus buffering'' behavior of water column particulate P (Fox et al 1985). Phosphorus buffering is the process by which P is desorbed from sediments to balance low seawater SRP concentration, as a result of anionic competition on surface adsorption sites or SRP biological uptake (Carritt and Goodgal 1954;Fox et al 1985;Froelich 1988). Our results show a decrease in the P content of TSS, a decrease in the labile-P and Fe-P, and an increase in the org-P and Ca-P components of particulate P (Fig.…”

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confidence: 99%

Effect of seasonal sediment storage in the lower Mississippi River on the flux of reactive particulate phosphorus to the Gulf of Mexico

Sutula

Bianchi

McKee

2004

Limnology & Oceanography

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The annual surface water flux of total reactive (i.e., potentially bioavailable) particulate P from the Mississippi River was estimated by measuring the reactive (including labile, iron, organic, and calcium bound) and nonreactive (detrital) P phases in suspended particulates in the Mississippi River. In addition, the transformation of the major sediment P phases resulting from seasonal channel storage and resuspension was examined. Samples were collected during five cruises over 1 yr at marine and riverine sites. Solid-phase and pore-water nutrients were quantified, and solid-phase P pools were measured using a sequential extraction technique. These results indicate that the Mississippi River exports 134 ϫ 10 6 kg yr Ϫ1 of total reactive P via surface water. Seasonal hydrological forcing controlled the variability in major P phases found in channel sediments through hydrodynamic sorting. Although the 6-9-month time period during which sediments were stored in the river channel was sufficient to see evidence of early diagenesis in the pore waters, no significant net effect was seen on major P phase distribution. The loss of a significant percentage of labile and iron-bound P appears to be occurring only as these riverine sediments are deposited and reworked on the continental shelf.Phosphorus is an important macronutrient that is thought to limit marine primary productivity, particularly on geological timescales (Holland 1994;Tyrell 1999). For this reason, the marine P budget has been the subject of intense study over the past 3 decades, and much effort has gone into estimating inventories and source and sink terms in the budget (Froelich et al.

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“…The influence of episodic sediment loading on phytoplankton communities varies with the composition, aging, chemical history, and loading rates of incoming soil (Sonzogni et al 1982;Cuker et al 1990) and algal species, physiological condition, and ion content of the water (Avnimelech et al 1982;Soballe and Threlkeld 1988). There are conflicting conclusions about the influence of sediment loading on phytoplankton communities and uncertainty about overall effects of suspended sediments on the community structure and physiology of phytoplankton in receiving waters (Hunter and Liss 1982;Fox et al 1985;Threlkeld and Soballe 1988;Cuker et al 1990). …”

mentioning

confidence: 99%

Phytoplankton and episodic suspended sediment loading: Phosphate partitioning and mechanisms for survival

Burkholder

1992

Limnol. Oceanogr.

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Enclosures within a turbid reservoir were used in combination with short-term laboratory experiments to examine some effects of suspended sediment loading on the community structure and phosphate uptake of the phytoplankton. Phytoplankton communities in duplicate field enclosures were treated at 7-d intervals for 8 weeks with a natural, fine-particulate clay in hydrated form, for comparison with species composition and abundances in communities from control enclosures without sediment additions. The phytoplankton community in field enclosures 7 d after final sediment addition was similar to that in controls (without sediment additions). The colonial blue-green Merismopedia punctata was dominant in cell number, and mixotrophic and heterotrophic dinoflagellates were dominant in biomass (based on cell surface area). The surprisingly diverse dinoflagellate assemblage consisted mostly of delicate athecate Gymnodinium spp. which were missed by conventional preservation techniques. Autoradiographs from short-term laboratory assays with trace concentrations of 33P0,3-revealed that clay particles adsorbed the radiolabel and also stimulated 33P043p uptake among all phytoplankton taxa examined. Algal uptake of radiolabeled P was highest immediately after sediment addition, indicating that one mechanism for survival under episodic sediment loading may be rapid uptake of POa3-for subsequent use after adverse conditions. Other apparent mechanisms involved in phytoplankton survival included rapid colony fragmentation (Merismopedia), partial or complete reliance on heterotrophy (dinoflagellates), and rapid formation of temporary cysts (dinoflagellates). Such mechanisms likely facilitate the characteristic resilience of abundant phytoplankton in turbid systems.

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Factors controlling the concentrations of soluble phosphorus in the Mississippi estuary1

Cited by 67 publications

References 20 publications

The dynamics of phosphorus in turbid estuarine systems: Example of the Gironde estuary (France)

The dynamics of phosphorus in turbid estuarine systems: Example of the Gironde estuary (France)

Effect of seasonal sediment storage in the lower Mississippi River on the flux of reactive particulate phosphorus to the Gulf of Mexico

Phytoplankton and episodic suspended sediment loading: Phosphate partitioning and mechanisms for survival

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