Institute of Hydraulic and Environmental Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China.
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
Environ Sci Pollut Res Int. 2018 Mar;25(9):8880-8887. doi: 10.1007/s11356-018-1217-x. Epub 2018 Jan 12.
Microbially mediated ammonium oxidation is a major process affecting nitrogen transformation and cycling in natural environments. This study investigated whether ion exchange process can affect microbially mediated aerobic oxidation of ammonium in a hyporheic zone (HZ) sediments from the Columbia River at US Department of Energy's Hanford site, Washington State. Experiments were conducted using synthetic groundwater and river water to investigate their effect on ammonium oxidation. Results indicated that ammonium sorption through ion exchange reactions decreased the rate of ammonium oxidation, apparently resulting from the influence of the ion exchange on dissolved ammonium concentration, thus decreasing the bioavailability of ammonium for microbial oxidation. However, with the decrease in dissolved ammonium concentration, the sorbed ammonium released back to aqueous phase, and became bioavailable so that all the ammonium in the suspensions were oxidized. Our results implied a dynamic change in ammonium oxidation rates in an environment such as at HZ where river water and groundwater with different chemical compositions exchange frequently that can affect ammonium sorption and desorption through ion exchange reactions.
微生物介导的氨氧化是影响自然环境中氮转化和循环的主要过程。本研究调查了离子交换过程是否会影响美国华盛顿州能源部汉福德（Hanford）场地哥伦比亚河潜流带（HZ）沉积物中微生物介导的有氧氧化氨。使用合成地下水和河水进行实验，以研究它们对氨氧化的影响。结果表明，通过离子交换反应吸附氨会降低氨氧化速率，显然是由于离子交换对溶解态氨浓度的影响，从而降低了氨对微生物氧化的生物利用度。然而，随着溶解态氨浓度的降低，被吸附的氨会释放回水相，并变得具有生物利用度，从而使悬浮液中的所有氨都被氧化。我们的结果表明，在像 HZ 这样的环境中，河水和地下水之间频繁地交换着具有不同化学成分的水，这会影响通过离子交换反应的氨吸附和解吸，从而导致氨氧化速率发生动态变化。
