养殖尾水氮元素在海水人工湿地中的迁移转化过程

Analysis of nitrogen migration and transformation in a constructed wetland treating mariculture tail water using stable isotopes

为深入探究养殖尾水中氮元素在海水人工湿地内的迁移转化过程,以牙鲆(Paralichthys olivaceous)养殖尾水为研究对象,利用氮稳定同位素技术示踪氮的迁移转化,并采用质量平衡法定量不同脱氮途径对人工湿地脱氮的贡献,以全面评估人工湿地系统的脱氮能力。结果表明,复合垂直流人工湿地对硝态氮有较好的处理效果。经21 d循环运行,NO_(3)^(−)-N氮去除率可达(92.81±1.21)%,湿地各基质层中煤渣层δ^(15)N值最低,为(203.58±2.87)‰,珊瑚石层δ^(15)N值最高,为(303.66±2.22)‰;植物中氮含量显著高于各层基质氮含量,平均氮含量为(2.68±0.38)%,其单位质量吸收氮素的能力最强,绝对丰度平均值为(105.61±14.65)×10^(−3)mg/g,远高于各基质层。系统初期基质、植物及微生物转化对系统脱氮的贡献率分别为44.70%、21.90%、18.11%;稳定期微生物转化则成为主要脱氮途径,贡献率高达60.77%,基质贡献率为6.46%。本研究结果全面揭示了海水养殖尾水中氮元素的去除效率和迁移转化过程,可为氮稳定同位素技术在海水人工湿地系统中的应用提供有效的数据支持,阐明了人工湿地各基质层和微生物的脱氮机理和贡献,可为海水养殖尾水脱氮技术的优化提供理论参考。

The migration and transformation of nitrogen in a seawater-constructed wetland treating Paralichthys olivaceus mariculture tail water was investigated using stable isotope technology.The study employed the mass balance method to quantify the contribution of different nitrogen removal pathways to overall nitrogen removal.showed that the compound vertical flow constructed wetland had a significant effect on nitrate nitrogen treatment,with a nitrogen removal rate of(92.81±1.21)%after 21 d of operation.Theδ^(15)N value of the coal residue layer was the lowest(203.58±2.87)‰,while the coral stone layer had the highestδ^(15)N value(303.66±2.22)‰.Plants exhibited the best capacity for nitrogen uptake,with an average nitrogen content of(2.68±0.38)%and an average absolute abundance of(105.61±14.65)×10^(-3) mg/g.Microbial transformation was found to be the main nitrogen removal pathway,accounting for 60.77%of the nitrogen removal.This study provides effective data support for applying stable isotope technology to the construction of seawater-constructed wetlands and clarifies the nitrogen removal process.