title: Stoichiometric determination of nitrate fate in agricultural ecosystems during rainfall events.
abstract: Ecologists have found a close relationship between the concentrations of nitrate (NO3-) and dissolved organic carbon (DOC) in ecosystems. However, it is difficult to determine the NO3- fate exactly because of the low coefficient in the constructed relationship. In the present paper, a negative power-function equation (r(2) = 0.87) was developed by using 411 NO3- data points and DOC:NO3- ratios from several agricultural ecosystems during different rainfall events. Our analysis of the stoichiometric method reveals several observations. First, the NO3- concentration demonstrated the largest changes when the DOC:NO3- ratio increased from 1 to 10. Second, the biodegradability of DOC was an important factor in controlling the NO3- concentration of agricultural ecosystems. Third, sediment was important not only as a denitrification site, but also as a major source of DOC for the overlying water. Fourth, a high DOC concentration was able to maintain a low NO3- concentration in the groundwater. In conclusion, this new stoichiometric method can be used for the accurate estimation and analysis of NO3- concentrations in ecosystems.
authors: Institute of Water Environment Rehabilitation, College of Environmental Science and Engineering, Tongji University, Shanghai, China.
authors: Zuxin
authors: Z
authors: Xu
authors: Institute of Water Environment Rehabilitation, College of Environmental Science and Engineering, Tongji University, Shanghai, China.
authors: Yiyao
authors: Y
authors: Wang
authors: Institute of Water Environment Rehabilitation, College of Environmental Science and Engineering, Tongji University, Shanghai, China.
authors: Huaizheng
authors: H
authors: Li
mesh_terms: D000383:Agriculture; D002244:Carbon / Q000032:analysis; D017753:Ecosystem; D004784:Environmental Monitoring; D060587:Groundwater / Q000737:chemistry; D009566:Nitrates / Q000032:analysis*; D011891:Rain / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical; D002244:Carbon