Xu Zuxin, Wang Yiyao, Li Huaizheng
Institute of Water Environment Rehabilitation, College of Environmental Science and Engineering, Tongji University, Shanghai, China.
PLoS One. 2015 Apr 7;10(4):e0122484. doi: 10.1371/journal.pone.0122484. eCollection 2015.
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.
生态学家发现生态系统中硝酸盐（NO3-）浓度与溶解有机碳（DOC）之间存在密切关系。然而，由于构建关系中的系数较低，难以准确确定NO3-的归宿。在本文中，利用不同降雨事件期间几个农业生态系统的411个NO3-数据点和DOC:NO3-比率，建立了一个负幂函数方程（r(2)=0.87）。我们对化学计量方法的分析揭示了几个观察结果。第一，当DOC:NO3-比率从1增加到10时，NO3-浓度变化最大。第二，DOC的生物降解性是控制农业生态系统中NO3-浓度的一个重要因素。第三，沉积物不仅是反硝化的场所，也是上覆水体中DOC的主要来源。第四，高DOC浓度能够使地下水中的NO3-浓度保持在较低水平。总之，这种新的化学计量方法可用于准确估算和分析生态系统中的NO3-浓度。
