Nitrogen and phosphorus speciation and flux in a large Florida River Wetland System

Abstract

Hydrologic measurements and analyses of various nitrogen and phosphorus species were made on the Apalachicola River system in northern Florida in 1979 and 1980. Annual outflows of total nitrogen (TN) and total phosphorus (TP) were not substantially different from annual inflows. However, there was significant net impørt of ammonia and soluble reactive phosphorus and net export of some particulate and organic species. The TN ß TP ratio ranged from 12 to 15, but the specific ratio of dissolved inorganic nitrogen' soluble reactive phosphorus was much higher (up to 40) and increased in a downstream direction; this contributed to a phosphorus-limiting situation in Apalachicola estuary. Processes within the flood plain ecosystem accounted for much of the release of organic and particulate species and retention of inorganic species. This flood plain function is probably critical for maintaining a nutrient pool in the estuary which supports secondary productivity and a detrital-based food web. INTRODUCTIONForested wetlands on large flood plains in tropical, subtropical, and warm temperate environments are likely to have a major impact on the riverine nutrient load as it flows through the system. This type of community is commonly characterized by high biomass [Schlesinger, 1978], high productivity [Leith, 1975], or both. The close interaction of the river and wetland results in direct exchange of matter and energy between them. Seasonal flooding not only increases the productivity of the wetland forest [Brinson et al., 1980], but also enhances the contribution of forest community growth to nutrient flux in the aquatic system [Day et al., 1977]. The precise nature of the wetland role in nutrient flux has been an enigma of wetland ecology. Thorough nutrient massbalance investigations of wetlands have been rare, although the need for more work has been expressed [Whigham and Bayley, 1979]. Current information indicates that highbiomass ecosystems tend to "internalize" some critical nutrient cycles [Reichle, 1975] as a means of conserving nutrient input [Whittaker et al., 1979]. Because of their capacity for nutrient conservation, wetlands often appear to function as sinks for nitrogen a. nd phosphorus [Simpson et al., 1978; Mitsch et al., 1979]. Some sanitary engineering practices call for utilization of wetland nutrient assimilation for wastewater treatment [Sloey et al., 1978; Tilton and Kadlec, 1979]. However, the balance of nutrient inputs and outputs may shift considerably, depending on numerous hydrologic and biological processes and the successional stage of the system [Gorham et al., 1979; Meyer and Likens, 1979]. Peverly [1982] found that a New York wetland could alternate between net export and net import, depending on the amount of flow through the system.Kowalczewski [1978] concluded that wetlands on lake borders do not act as important sinks for nutrients and can contribute constant transport of dissolved organics into the lake.One factor that is apparently critical to the role of wetlands in nutrient flux is ...

Input, movement and exchange of organic matter within a subtropical coastal black water river‐flood plain system

“…Disturbances of this kind would significantly reduce the amount of litter entering the river and being re-incorporated into new floodplain (i.e. deep storage) or exported to estuaries (Elder, 1985). If deep floodplain organic matter storage is reduced, then floodplain fertility and nutrient relationships would be altered, and the pH, colour and concentration of DOM would change.…”

Leaf Litter Decomposition and Nutrient Dynamics in Four Southern Forested Floodplain Communities

“…Decomposition processes in wetland and floodplain environments have also received considerable attention with regard to biogeochemical (i.e., intersystem) nutrient cycling (Brinson, 1977;Brinson, 1981;Elder, 1985;Brinson, 1993;Lockaby and Walbridge, 1998). Particularly in floodplain systems, significant quantities of nutrients may be imported from upslope and/or upstream ecosystems through riparian transport or in floodwaters.…”

Application of chemical mass balance approach to determine nutrient loading

“…However, the requirement for a vast amount of data has placed several constraints on model applications under Indian conditions. The chemical mass balance approach has been used extensively during recent years to study in-stream reactions and sediment dynamics (Plummer & Back, 1980;Christophersen & Wright, 1981;Elder, 1985;Latimer et al, 1988;Yuretich & Batchelder, 1988).…”