Kr. Reddy et al., PHOSPHORUS SORPTION CAPACITIES OF WETLAND SOILS AND STREAM SEDIMENTS IMPACTED BY DAIRY EFFLUENT, Journal of environmental quality, 27(2), 1998, pp. 438-447
The ability of stream sediments and adjacent wetlands to retain added
P depends on the P sorption capacity and physico-chemical properties o
f sediments or wetland soils, The objectives of this study were to: (i
) determine the potential P sorption capacities of wetland soils and s
tream sediments in systems with distinctly different P loadings, and (
ii) establish the relationship between P sorption rapacity and selecte
d physico-chemical properties. Batch sorption isotherms were measured
under aerobic and anaerobic conditions for sediments and wetland soils
along a stream-wetland-upland continuum at two sites in the Lower Kis
simmee River Basin and Taylor Creek/Nubbin slough of the Okeechobee Ba
sin, Florida. Soluble P and equilibrium P concentrations (EPC) of stre
am sediments generally decreased along the wetland-upland continuum, T
he EPC values were about twofold greater under anaerobic renditions th
an aerobic conditions; however, P sorption capacities decreased by abo
ut 35% under anaerobic conditions compared with aerobic conditions. Th
e P sorption maxima, estimated by a single point isotherm measured at
an added P level of 1000 mg P kg(-1), correlated well with Langmuir ad
sorptive mar;ima. Phosphorus retention by stream sediments and wetland
soils was strongly correlated with contents of amorphous and poorly c
rystalline forms of Fe and Al, which explained 87% of the variability
in P retention maximum. Addition of total organic C to predictive equa
tions improved the predictability by only 5%.