Key Laboratory of Marine Environment Science and Ecology, Ministry of Education and College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China.
J Hazard Mater. 2023 Apr 15;448:130976. doi: 10.1016/j.jhazmat.2023.130976. Epub 2023 Feb 9.
The main cause of groundwater nitrate contamination is the continual downward migration of dissolved nitrogen (N) in vadose zone with leachate. In recent years it has been found that dissolved organic N (DON) rise to forefront due to its great migration capacity and environmental effects. However, it remains unknown how the transformation behaviors of DONs with different properties in vadose zone profile may impact N forms distribution and groundwater nitrate contamination. To address the issue, we conducted a series of 60-day microcosm incubation experiments to investigate the effects of various DONs transformation behaviors on the distribution of N forms, microbial communities, and functional genes. The results revealed that urea and amino acids mineralized immediately after substrates addition. By contrast, amino sugars and proteins caused less dissolved N throughout entire incubation period. The transformation behaviors could substantially alter the microbial communities. Moreover, we discovered that amino sugars remarkably increased the absolute abundances of denitrification function genes. These results delineated that DONs with unique characteristics (such as amino sugar) promoted different N geochemical processes in distinct ways: different contributions to nitrification and denitrification. This can provide new insights for nitrate non-point source pollution control in groundwater.
地下水硝酸盐污染的主要原因是渗滤带中溶解态氮（N）的持续向下迁移。近年来，由于其巨大的迁移能力和环境影响，溶解有机氮（DON）已上升到首要地位。然而，目前尚不清楚不同性质的 DON 在包气带剖面中的转化行为如何影响 N 形态的分布和地下水硝酸盐污染。为了解决这一问题，我们进行了一系列 60 天的微宇宙培养实验，以研究各种 DON 转化行为对 N 形态分布、微生物群落和功能基因的影响。结果表明，脲和氨基酸在添加底物后立即矿化。相比之下，在整个培养期间，氨基糖和蛋白质对溶解态 N 的影响较小。转化行为会显著改变微生物群落。此外，我们发现氨基糖显著增加了反硝化功能基因的绝对丰度。这些结果表明，具有独特特征的 DON（如氨基糖）以不同的方式促进了不同的 N 地球化学过程：对硝化和反硝化的不同贡献。这可为地下水硝酸盐非点源污染控制提供新的见解。
