Coupling Genomics and Hydraulic Information to Predict the Nitrogen Dynamics in a Channel Confluence

The
simulation of nitrogen dynamics in urban channel confluences
is essential for the evaluation and improvement of water quality.
The omics-based modeling approaches that have been rapidly developed
have been increasingly applied to characterize metabolisms of the
microbial community and transformation of the associated materials.
However, the transport of microorganisms and chemicals within and
among different phases, which could be the rate-limiting step for
the nitrogen dynamics, are always neglected or oversimplified in omics-based
models. Therefore, this study proposes a novel simulation system coupling
genomic and hydraulic information to simulate transport and transformation
processes and provide predictions of nitrogen dynamics in a confluence.
The proposed model was able to capture multiphase mass transport,
microbial population dynamics, and nitrogen transformation and accurately
predict gene abundances and nitrogen concentrations in both water
and sediment; the mean relative errors were all lower than 40%. The
model emphasized the importance of transport processes, which contributed
more than 90% to gene abundances and chemical concentrations. Moreover,
the simulation of reaction rates exhibited the specific nitrogen transformation
processes in the confluence. The sulfide oxidation and the nitrate
reduction and anaerobic ammonium oxidation, with the participation
of the genes nap and hzo, respectively,
were promoted as the main processes of nitrate and nitrite reduction.