Department of Environmental Science and Engineering, College of Natural Resource and Environment, South China Agricultural University, Guangzhou, 510642, China.
Department of Environmental Science and Engineering, College of Natural Resource and Environment, South China Agricultural University, Guangzhou, 510642, China.
Environ Res. 2020 Nov;190:109979. doi: 10.1016/j.envres.2020.109979. Epub 2020 Jul 31.
Nitrate-driven sulfide/ferrous oxidation has been proved a cost-effective approach for river sediments in-situ odor control. However, calcium nitrate addition would sharply increase ammonium concentration in interstitial water and the mechanism was not yet clear. In this work, though sulfide and ferrous iron were efficiently oxidized, about 102% of NH concentration increased in interstitial water on the first day of calcium nitrate injection (30 mg kg dwt), and about 31% more NH increase at the 21st days was observed. To discover the mechanism of ammonium sharp release, desorption kinetics experiment was conducted and the results suggested that the short-time sharp releases of ammonium when calcium nitrate was added could be attributed to the chemical extraction of exchangeable ammonium by calcium ion. Furthermore, at the end of treatment, many genus such as Thiobacillus, Sulfurimonas, Thermomonas, and Clostridium, which were closely related to sulfide and ferrous-driven denitrification and dissimilatory nitrate reduction to ammonium (DNRA), were identified by 16S rRNA Illumina sequencing method. These findings indicated the long-time increase of ammonium might be determined by the biochemical processes (e.g. DNRA) driven by nitrate reduction. Therefore, to avoid the impact of ammonium release, an alternative subsurface injection method was introduced in this work, and the results showed that ammonium releases could be well controlled when the injection position was beneath 10 cm of the sediment surface.
硝酸盐驱动的硫化物/亚铁氧化已被证明是原位控制河流沉积物气味的一种经济有效的方法。然而，添加硝酸钙会显著增加间隙水中的铵浓度，但其机制尚不清楚。在这项工作中，尽管有效地氧化了硫化物和亚铁，但在添加硝酸钙的第一天，间隙水中的 NH浓度增加了约 102%（30mgkgdw），在第 21 天观察到的 NH 增加了约 31%。为了发现铵急剧释放的机制，进行了解吸动力学实验，结果表明，添加硝酸钙时铵的短时间急剧释放可归因于钙离子对可交换铵的化学提取。此外，在处理结束时，通过 16S rRNA Illumina 测序方法鉴定了许多与硫化物和亚铁驱动的反硝化和异化硝酸盐还原为铵（DNRA）密切相关的属，如硫杆菌属、硫单胞菌属、嗜热单胞菌属和梭菌属。这些发现表明，铵的长时间增加可能由硝酸盐还原驱动的生化过程（如 DNRA）决定。因此，为了避免铵释放的影响，本工作中引入了一种替代的地下注入方法，结果表明，当注入位置在沉积物表面以下 10cm 时，铵的释放可以得到很好的控制。
