Nitrate Reduction In Riparian Soils In Forest And Cropland Landscapes

The terrestrial water bodies have been more or less seriously polluted world widely. Nitrogen is one of the most important elements responsible for water pollution. Non-point pollution is the major pathway through which nitrogen pollutants enter terrestrial water bodies. Riparian zones play vital role in controlling the transportation of nitrogen from adjacent highland to waters. The denitrification potential of soils from forested and bare riparian zones in cropland landscape, forested, clearcut and grassy riparian in forest landscape was studied by anaerobic incubation, with the following major results:1. With in the incubation period(l, 3, and 5 days, respectively), soil samples in forest background had a greater denitrification potential than that in cropland, with the removal rate of nitrate between 31.57%—87.87%, and .14.85%—81.59%,respectively;2. The nitrate removal rate in soil samples from forested "riparian zone in cropland landscape was greater than that from bare riparian zone, with the variation of nitrate removal between 46.79%~91.13% and 15.64% —81.84%, respectively in the incubation period;3. The ranking of nitrate removal rate in soil samples from different riparian zones in forest landscape was clearcut riparian zone > forested riparian zone > grassy riparian zone, with the nitrate removal rate varied between 42.06% - 90.39%, 28.24% — 85.73%, and 21.44%~83.11%, respectively;4. The greatest and lowest nitrate removal rates in soil samples from all riparian zones were detected in forested riparian zone and bare riparian zone in cropland landscape, respective. The variation range of nitrate removal rate was 46.79% —91.13% and 15.64% —81.84%, respectively;5. The nitrate removal rate in upper layer soil samples was greater than that from lower layer, with the range of nitrate removal rate between 48.22% —91.13 % in upper layer soils, and 15.64%—76.67% in the lower layer ones;6. The removal of nitrate in all soil samples were all checked by available organic carbon as well as nitrate. Glucose addition treatment shifted the variation range of nitrate removal from 15.64%~79.60%. to 37.35%— 96.49%;with nitrate addition treatment, nitrate removal range changed from 15.64%—79.60% to 66.68% — 99.06%? Great denitrition potential was found with soil samples from forested riparian zone in cropland landscape, with the nitrate removal rate range varied between 96.82%—99.06%.