Nitrogen mass balance and denitrification rates in Lagunas de Ruidera Natural Park, Spain

Abstract

Human activities have dramatically changed the global nitrogen cycle. Extensive agricultural overfertilization has increased the worldwide supply of nitrogen to freshwaters in recent decades (VITOUSEK et al. 1997). Due to the negative impact of increasing nitrogen concentration on the function o f aquatic systems, the study of mechanisms reducing nitrogen concentration downstream has gained importance. Denitrification, sedimentation and uptake by plants (SAUNDERS et al. 2001) are the main mechanisms of nitrogen retention in aquatic systems, and these studies are expanding topics in limnology (STEI'iGRUBER et al. 2001). However, data on denitrification rates in lakes o f semiarid regions are lacking. The aims o f this study were to estimate total nitrogen elimination rates in a semiarid lake using the mass-balance approach. which is well suited to estimate biogeochemical cycles in lakes; to determine the importance o f denitrification to nitrogen budgets in that lake; and to suggest control variables o f denitrification on a yearly basis in lakes worldwide.