Phosphate removal capacity of palustrine forested wetlands and adjacent uplands in Virginia

作者：Axt JR^*; Walbridge MR

来源：Soil Science Society of America Journal, 1999, 63(4): 1019-1031.

DOI：10.2136/sssaj1999.6341019x

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) = 0.83). 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.

• 出版日期1999-8