Characterization of suspended particles in Everglades wetlands

Noe, Gregory B., Judson W. Harvey, James E. Saiers

Limnol. Oceanogr., 52(3), 2007, 1166-1178 | DOI: 10.4319/lo.2007.52.3.1166

ABSTRACT: We report the concentration, phosphorus (P) and nitrogen (N) content, and size and chemical fractionation of fine suspended particles (0.2-100 µm) and colloids (3 kilodalton [kDa]-0.1 µm) in the surface water of Everglades wetlands along regional and P-enrichment gradients. Total suspended sediment concentrations ranged from 0.7 to 2.7 mg L-1. Total particulate P concentrations increased from 0.05 µmol L21 to 0.31 µmol L-1 along the Penrichment gradient. Particles contained from 20% to 43% of total P but <12% of total N in surface water. Dissolved (<0.2 µm) organic N contained about 90% of total N, with the 3-100-kDa colloidal size class containing the most N of any size class. The 0.45-2.7-µm size fraction held the most particulate P at all sites, whereas particulate N was most abundant in the 2.7-10-µm size class at most sites. Standard chemical fractionation of particles identified acid-hydrolyzable P as the most abundant species of particulate P, with little reactive or refractory organic P. Sequential chemical extraction revealed that about 65% of total particulate P was microbial, while about 25% was associated with humic and fulvic organic matter. The size and chemical fractionation information suggested that P-rich particles mostly consisted of suspended bacteria. Suspended particles in Everglades wetlands were small in size and had low concentrations, yet they stored a large proportion of surface-water P in intermediately reactive forms, but they held little N.

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