Retention of carbon and nutrients in wetlands receiving agricultural runoff

In this study, it is aimed to examine time-dependent changes in sediment, carbon, nitrogen and phosphorus accumulation in sediment cores and to determine of relationships among each other in riparian, permanently and seasonally flooded wetlands in agricultural watersheds. The organic matter and carbon accumulation was found to be high in the surface zone and to decrease with depth. However, depending on depth, the organic matter and carbon accumulation were higher compared with other areas in the riparian zone which is a natural wetland. It is known that, in terms of carbon accumulation, anaerobic processes in natural wetlands and carbon input amount in restored wetlands is important. Nitrogen accumulation in cores shows a similar trend like organic matter and carbon accumulation. The accumulation of phosphorus was found to be higher in the seasonally flooded wetland which was used previously pasture. Sedimentation rates were calculated using the CRS (Constant Rate Supply) model and 210Pb was found to have the highest value in the first 15 cm in the sediment cores. Sedimentation rate was higher in the riparian permanently flooded wetland than in other areas and depending on the sedimentation rate this area is expected to fill up in the next 25 years.