Review: Denitrification in temperate climate riparian zones

Excess nitrate (NO3-) in lakes and streams has deleterious effects for envi ronmental and human health. Nitrate concentrations have become problematic in agricultural watersheds due to increased use of fertilizers and improper management of livestock wastes. Research has indicated that the planting a nd/or preservation of riparian buffer zones can be an effective means of re ducing pollution from agricultural fields (Osborne and Kovacic, 1993; Jorda n et al., 1992; Simmons el al., 1992). Biological denitrification is the mo st desirable means of nitrate attenuation as the microbial conversion of NO 3- removes nitrate from the watershed in the form of N gases. Despite the i nherent value of biological denitrification, a comprehensive review discuss ing the role of this process in removing nitrate from riparian zones is lac king. In this paper we examine the results and conclusions of past research on the topic of denitrification in riparian zones and make recommendations for future research in this area. The need for subsurface denitrification assays in riparian zones is emphasized.