Nitrate Sources and Nitrogen Biogeochemical Processes in the Feng River Inferred from Nitrogen and Oxygen Dual Isotope Measurements of Nitrate
A portion of nitrogen from watersheds enters river networks,degrades river water quality and causes subsequent eutrophication of downstream river.Identifying the source of nitrate in rivers is the primary work to control excessive nitrogen input to rivers.In this paper,nitrate sources in the Feng River were inferred from nitrate dual isotopes (815Nnitrate and 8180nitrate) combined with the water quality data,and nitrogen biogeochemical processes were further explored.The results indicated that N03 -N is the stable form of nitrogen in the Feng River system.The annual average content of nitrate was 3.21 mg I L,about 83% of the total nitrogen content.In September of 2012,the 815Nnitrate and 8180nitrate values suggested atmospheric deposition and soil organic nitrogen were the main sources of nitrate in upstream; atmospheric deposition,chemical fertilizer and sewage & manure inputs were the sources in downstream with their average contribution ratios of 68.4%,19%,and 12.6%,respectively.In December of 2011,the 815Nnitrate and 8180nitrate values suggested nitrate in upstream was mainly derived from soil organic nitrogen; nitrate in downstream was derived mainly from sewage and manure inputs.For sewage & manure inputs,chemical fertilizer and soil organic nitrogen,their average contribution ratios were 68%,22%,10%,respectively.The 8180nitrate data indicated most of nitrate from microbial nitrification could possibly make a significant contribution to Feng River system.The variations in isotopic values of nitrate suggested that denitrification enriched the heavier isotopes of nitrate in upstream and midstream of Feng River in summer.The isotopic characteristics of phytoplankton uptake for nitrogen were obvious in the Feng River downstream in April 2012.Nitrogen biogeochemical processes of the Feng River water system is the result of mixing of denitrification and phytoplankton uptake etc..
Nitrate sources Nitrogen and oxygen dual isotopes Nitrogen biogeochemical processes denitification Feng River
Aizhong Ding Jianhui Zhi Shurong Zhang Chengzhong Pan Desheng Chen Xuan Zhao Mengjiao Ma Zhenghong Yan
国际会议
2013青岛国际脱盐大会(Qingdao International Conference 2013 on Desalination and Water Reuse)
青岛
英文
19-24
2013-06-25（万方平台首次上网日期，不代表论文的发表时间）