naa a22 4500 510749747 CHVBK 20180411083100.0 cr unu---uuuuu 180411e20130901xx s 000 0 eng 10.1007/s11270-013-1693-z doi (NATIONALLICENCE)springer-10.1007/s11270-013-1693-z Quantification of In Situ Denitrification Rates in Groundwater Below an Arable and a Grassland System [Elektronische Daten] [M. Jahangir, P. Johnston, K. Addy, M. Khalil, P. Groffman, K. Richards] Understanding denitrification rates in groundwater ecosystems can help predict where agricultural reactive nitrogen (N) contributes to environmental degradation. In situ groundwater denitrification rates were determined in subsoil, at the bedrock interface and in bedrock at two sites, grassland and arable, using an in situ ‘push-pull' method with 15N-labelled nitrate (NO3 −-N). Measured groundwater denitrification rates ranged from 1.3 to 469.5μgNkg−1day−1. Exceptionally high denitrification rates observed at the bedrock interface at grassland site (470 ± 152μgNkg−1day−1; SE, standard error) suggest that deep groundwater can serve as substantial hotspots for NO3 −-N removal. However, denitrification rates at the other locations were low and may not substantially reduce NO3 −-N delivery to surface waters. Denitrification rates were negatively correlated with ambient dissolved oxygen, redox potential, k s and NO3 − (all p values, p < 0.01) and positively correlated with SO4 2− (p < 0.05). Higher mean N2O/(N2O + N2) ratios at an arable (0.28) site than the grassland (0.10) revealed that the arable site has higher potential to indirect N2O emissions. Identification of areas with high and low denitrification and related site parameters can be a tool to manage agricultural N to safeguard the environment. Springer Science+Business Media Dordrecht, 2013 Denitrification nationallicence 15N-enrichment nationallicence 15N-N2O nationallicence 15N-N2 nationallicence Groundwater nationallicence N2O mole fraction nationallicence Jahangir M. Teagasc Environment Research Centre, Johnstown Castle Estate, Co. Wexford, Ireland aut Johnston P. Department of Civil, Structural and Environmental Engineering, Trinity College, Dublin, Ireland aut Addy K. Department of Natural Resources Science, University of Rhode Island, One Greenhouse Road, 02816, Kingston, RI, USA aut Khalil M. Environmental Protection Agency, Johnstown Castle Estate, Co. Wexford, Ireland aut Groffman P. Cary Institute of Ecosystem Studies, P.O. Box AB, 12545, Millbrook, NY, USA aut Richards K. Teagasc Environment Research Centre, Johnstown Castle Estate, Co. Wexford, Ireland aut Water, Air, & Soil Pollution Springer Netherlands 224/9(2013-09-01), 1-14 0049-6979 224:9<1 2013 224 11270 https://doi.org/10.1007/s11270-013-1693-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11270-013-1693-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jahangir M. Teagasc Environment Research Centre, Johnstown Castle Estate, Co. Wexford, Ireland aut NATIONALLICENCE 700 1- Johnston P. Department of Civil, Structural and Environmental Engineering, Trinity College, Dublin, Ireland aut NATIONALLICENCE 700 1- Addy K. Department of Natural Resources Science, University of Rhode Island, One Greenhouse Road, 02816, Kingston, RI, USA aut NATIONALLICENCE 700 1- Khalil M. Environmental Protection Agency, Johnstown Castle Estate, Co. Wexford, Ireland aut NATIONALLICENCE 700 1- Groffman P. Cary Institute of Ecosystem Studies, P.O. Box AB, 12545, Millbrook, NY, USA aut NATIONALLICENCE 700 1- Richards K. Teagasc Environment Research Centre, Johnstown Castle Estate, Co. Wexford, Ireland aut NATIONALLICENCE 773 0- Water, Air, & Soil Pollution Springer Netherlands 224/9(2013-09-01), 1-14 0049-6979 224:9<1 2013 224 11270 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer