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Phosphate Removal Capacity of Palustrine Forested Wetlands and Adjacent Uplands in Virginia
Author(s) -
Axt J. R.,
Walbridge M. R.
Publication year - 1999
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1999.6341019x
Subject(s) - wetland , sorption , soil water , environmental science , hydrology (agriculture) , surface runoff , environmental chemistry , organic matter , soil organic matter , soil science , geology , chemistry , ecology , geotechnical engineering , organic chemistry , adsorption , biology
We examined the ability of soils in six nontidal palustrine forested wetlands (PFOs) in Virginia's Piedmont (PD) and Coastal Plain (CP)( n = 3 per physiographic province )to remove dissolved inorganic P from solution, and we compared the P sorption capacities of wetlands with those of streambanks (within wetlands) and adjacent uplands. We hypothesized that wetland soils would have higher P sorption capacities than streambank and upland soils due to the higher concentration of noncrystalline (oxalate‐extractable) Al and Fe (Al o and Fe o ) favored by periodic flooding. We found that P sorption capacities varied both as a function of landscape position and soil depth. Wetlands had higher P sorption capacities than uplands in surface soils (0–15 cm), while below 50 cm the relationship was reversed. Streambank areas within wetlands generally had the lowest P sorption capacities. As hypothesized, Al o was correlated with P sorption capacity in wetland soils( r 2 = 0.80 ), but so was soil organic matter (as estimated by mass loss on ignition [LOI])( r 2 = 0.78 ); in fact, Al o and organic matter were positively correlated in wetland soils( r 2 = 0.84 )In contrast, clay and silt content were the two soil parameters most highly positively correlated with P sorption capacity in upland soils( r 2 = 0.87 )Overall, these results suggest that differences in soil chemistry exist among landscape positions (wetland, streambank, upland) that have important implications with regard to P sorption capacity. Since wetlands and uplands may remove P from different hydrologic sources (i.e., surface runoff in wetlands and groundwater in uplands), hydrology may be a key factor in determining water quality functioning.