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Factors Controlling Seasonal Nutrient Profiles in a Subtropical Peatland of the Florida Everglades
Author(s) -
KochRose M. S.,
Reddy K. R.,
Chanton J. P.
Publication year - 1994
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1994.00472425002300030018x
Subject(s) - eutrophication , nutrient , macrophyte , soil water , mineralization (soil science) , environmental chemistry , environmental science , wetland , dissolved organic carbon , chemistry , hydrology (agriculture) , ecology , biology , soil science , geotechnical engineering , engineering
Approximately 75% of soil nutrients in the Everglades are stored in the organic form; thus, factors affecting seasonal organic matter and associated nutrient mineralization will influence nutrient availability to marsh vegetation. To assess the factors controlling mineralization in the field, pore water nutrients including NH + 4 , NO − 3 and, soluble reactive P (SRP) were determined along with soil Eh, pH, temperature, and water levels at eutrophic, mesotrophic, and oligotrophic sites through a dry and rainy season. Indicators of anaerobic microbial activity, SO 2− 4 , methane (CH 4 ), CH 4 ‐stable isotope signatures, and dissolved inorganic carbon (DIC) were sampled at all three sites. At the enriched site, SRP and NH + 4 levels were 95 and 706 µ M during summer months and 11 and 26 µ M spring concurrent with N/P ratios of three and maximum macrophyte growth. Low seasonal variability in SRP was found at oligotrophic sites where pore water N/P ratios ranged from 39 to 551 throughout the year. During the spring dry season, Eh exceeded 300 mV at all three sites. In all other seasons, soils remained flooded and Eh averaged −100 to −200 mV. Methane and DIC, and isotopic 13 C ratios in the eutrophic sites, relative to those found under oligotrophic conditions, suggest greater microbial production rates at enriched sites. Oligotrophic Everglades soils appear to have limited microbial activity and consequently, dampened seasonal pore water nutrient levels in response to fluctuating Eh, pH, water level, and temperature regimes.