Nitrogen biogeochemistry of aquaculture ponds

Nitrogen transformations and balance in channel catfish ponds

“…Denitrification rates in this study (Fig. 1) were within the range commonly encountered in eutrophic aquatic systems (Hargreaves, 1995).…”

“…The estimated N loss through denitrification averaged 1846 g pond − 1 or 17.36% of the N loss (Table 3). Denitrification rate varies with temperature, pH, abundance of denitrifying bacteria, and concentrations of NO 3 N, organic C, and DO (Hargreaves, 1995). Dissolved oxygen concentrations in pond waters were greater than 3 mg l − 1 , and it is unlikely that much denitrification occurred in the water column.…”

“…1), and the estimated average was 70 mg N m − 2 d − 1 . Possibly there was additional nitrification in the surface layer of bottom soil (Hargreaves, 1995;Word, 1996) that was not included. The mineralization rate of TAN from feed was 58.7 mg N m − 2 d − 1 that is less TAN than needed for the observed rate of nitrification.…”

“…There have been many studies of N dynamics in aquaculture ponds (Hargreaves, 1998). Some of these studies provided partial or complete N budgets.…”

“…Studies by Krom and Neori (1989), Acosta-Nassar et al (1994), and Briggs and Funge-Smith (1994) also provide estimates of N inputs and outputs to ponds. According to Hargreaves (1998), there is still a need for a more complete understanding of factors regulating ammonia and nitrite concentrations and exchange of nitrogenous compounds between sediment and water in aquaculture ponds.…”