Use of 15N Natural Abundance and N Species Concentrations to Assess N-Cycling in Constructed and Natural Coastal Wetlands. (23rd May 2010) - Aelion, C. Marjorie
Abstract : Natural abundance of N stable isotopes used in combination with concentrations may be useful indicators of N-cycling in wetlands. Concentrations and 15 N signatures ofNO 3 −, NH 4 +, and sediment organic nitrogen (SON) were measured in two impacted coastal golf course retention ponds and two natural marshes. LimitedNO 3 − was detected in natural site surface water or pore water, but both isotopic signature and concentrations ofNO 3 − in surface water of impacted sites indicated anthropogenic inputs. In natural sites, NH 4 + concentrations were greatest in deeper pore water and least in surface water, suggesting diffusion predominates. The natural sites had greater %SON, and 15 N indicated that the natural sites also had greaterNH 4 + released from SON mineralization than impacted sites. InNO 3 − -limited systems, neither concentrations nor 15 N natural abundance was able to provide information on N-cycling, while processes associated withNH 4 + were better elucidated by using both concentrations and 15 N natural abundance.