Abstract

The Nitrogen cycle in wetlands plays an important role in transport,storage and biological availability of nitrogen in the surrounding watershed.

We described seasonal variations(2005-2006)in nitrogen cycling parameters at three wetlands’surface water.These wetlands were located in three different types of area and the percentage of forest area that surrounded them was different. Wetland A is located at forested area(100%),wetland B is located at mid forested area(50%)and wetland C is located at urban area(>75%).

Surface water in each wetland at five points (input,output and three samples of inside)were sampled monthly and then analyzed for Nitrate, Nitrite, Ammonium and Total Nitrogen.

The results indicated that in wetland A, the concentration of nitrate is dominant(ca. 0.09mg/l)in winter during plant dormancy and that of ammonium is dominant(ca. 0.06mg/l)in spring/summer when wetland plants were beginning yearly production cycles. In wetland B, nitrate and ammonium were dominated (ca. 0.09,0.2mg/l)in winter and for wetland C, nitrate was dominated(ca. 1.2mg/l)in autumn and ammonium was dominated(ca. 2.6mg/l)in winter.

We found that additional to the role of plants in changing the concentration of the inorganic nitrate, other factors consisting of the surrounding land uses(urbanization)are of significant role in dynamic of nitrogen in wetland’s surface water.