Phosphorus flux sediments

Calcium carbonate precipitation and sedimentation from mid-August through October (ref. 20 see also the following discussion of components) significantly enhanced P fluxes. The impact of calcite precipitation on P removal from the epilimnion is shown in Figure 8. Phosphorus flux into the... 

Figure 6. Phosphorus flux to the sediment surface. The total flux over study period was 185 mg/m2.

Figure 7. Isopleths of phosphorus flux (micrograms per square meter per day) in the water column, measured hy using sediment traps. The values are the...

Figure 8. Downward areal flux (sediment-trap-measured) of phosphorus at 29 m during the period of thermal stratification.

The amount of P supplied by resuspension was relatively small compared with water-column standing pools and major flux vectors. Thus, resuspension of bottom sediments may not be a major mode of phosphorus resupply. The pool of resuspendable P is finite. The deposition-resuspension cycle will not increase the amount of P in this pool unless P is added from another source (e.g., by diffusion of P from lower sediment levels). However, the diffusive flux would be relatively small. The resuspendable particulate P can be recycled during spring mixing by repeated deposition and resuspension, but this cycle does not increase the amount of P in the resuspendable pool. Eadie et al. (24) reported a resuspended P flux (sediment-trap-based) of3200 mg of P/m2, 66 times our estimate here. However, this large P flux would require the resuspension of over 2.0 cm of surface sediment and much higher suspended Al levels than were measured in the water column. 

Phosphorus Fluxes Across the Sediment-Water Interface... 

Berner, R.A., and Rao, J. (1994) Phosphorus in sediments of the Amazon River and estuary implications for the global flux of phosphorus to the sea. Geochim. Cosmochim. Acta 38, 2333-2339. 

Increased erosion due to forest clear-cutting and widespread cultivation has increased riverine suspended matter concentrations, and thus increased the riverine particulate-P flux. Dams, in contrast, decrease sediment loads in rivers and therefore diminish the phosphorus flux to the oceans. However, increased erosion below dams... 

Carlton R. G. and Wetzel R. G. (1988) Phosphorus flux from lake sediments effect of epipelagic algal oxygen production. Limnol. Oceanogr. 33, 562—570. 

Fig. 16.5. Particulate phosphorus flux to the sediment as measured during 1984 (Sigg et ai, 1987 dashed line) and calculated for 1990 (solid line). Reproduced from Omiin etal. (2001a) with permission from Elsevier Science.

Reactive Phosphorus Fluxes from Sediments to Overlying Anoxic or Oxic Conditions... 

Malecki, L. M., J. R. White, and K. R. Reddy. 2004. Nitrogen and phosphorus flux rates from sediment in the lower St. Johns River estuary. J.Environ. Qual. 33 1545-1555. 

Moore, P. A., K. R. Reddy, and M. M. Fisher. 1998. Phosphorus flux between sediment and overlying water in Lake Okeechbee, Florida spatial and temporal variations. J. Environ. Qual. 27 1428-1439. 

Reddy, K. R. and M. M. Eisher. 1991. Sediment resuspension effects on phosphorus flux across the sediment-water interface laboratory microcosm studies. In Lake Okeechobee Phosphorus Dynamics Study Biogeochemical Processes in the Sediments. Volume V. Einal Report submitted to South Florida Water Management District (Contract No. 531-M88-0445-A4), West Palm Beach, FL. 

Cai LS, Fang JG, Dong SL (2004) Preliminary studies on nitrogen and phosphorus fluxes between seawater and sediment in Sungo Bay. Mar Fish Res 25(4) 57-64 (in Chinese with Enghsh abstract)... 

The destiny of most biological material produced in lakes is the permanent sediment. The question is how often its components can be re-used in new biomass formation before it becomes eventually buried in the deep sediments. Interestingly, much of the flux of phosphorus is held in iron(lll) hydroxide matrices and its re-use depends upon reduction of the metal to the iron(ll) form. The released phosphate is indeed biologically available to the organisms which make contact with it, so the significance attributed to solution events is understandable. It is not clear, however, just how well this phosphorus is used, for it generally remains isolated from the production sites in surface waters. Moreover, subsequent oxidation of the iron causes re-precipitation of the iron(lll) hydroxide floes, simultaneously scavenging much of the free phosphate. Curiously, deep lakes show almost no tendency to recycle phosphorus, whereas shallow... 

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