TY - CONF
T1 - Evaluation of reaction rates in streambed sediments with seepage flow: a novel code
AU - Boano, Fulvio
AU - De Falco, Natalie
AU - Arnon, Shai
PY - 2015/4/1
Y1 - 2015/4/1
N2 - Streambed interfaces represent hotspots for nutrient transformations
because they host different microbial species which perform many
heterotrophic and autotrophic reactions. The evaluation of these
reaction rates is crucial to assess the fate of nutrients in riverine
environments, and it is often performed through the analysis of
concentrations from water samples collected along vertical profiles. The
most commonly employed evaluation tool is the Profile code developed by
Berg et al. (1998), which determines reaction rates by fitting observed
concentrations to a diffusion-reaction equation that neglects the
presence of water flow within sediments. However, hyporheic flow is
extremely common in streambeds, where solute transport is often
controlled by advection rather than diffusion. There is hence a pressing
need to develop new methods that can be applied even to
advection-dominated sediments. This contribution fills this gap by
presenting a novel approach that extends the method proposed by Berg et
al. (1998). This new approach includes the influence of vertical solute
transport by upwelling or downwelling water, and it is this suited to
the typical flow conditions of stream sediments. The code is applied to
vertical profiles of dissolved oxygen from a laboratory flume designed
to mimic the complex flow conditions of real streams. The results show
that it is fundamental to consider water flow to obtain reliable
estimates of reaction rates in streambeds. Berg, P., N.
Risgaard-Petersen, and S. Rysgaard, 1998, Interpretation of measured
concentration profiles in the sediment porewater, Limnology and
Oceanography, 43:1500-1510.
AB - Streambed interfaces represent hotspots for nutrient transformations
because they host different microbial species which perform many
heterotrophic and autotrophic reactions. The evaluation of these
reaction rates is crucial to assess the fate of nutrients in riverine
environments, and it is often performed through the analysis of
concentrations from water samples collected along vertical profiles. The
most commonly employed evaluation tool is the Profile code developed by
Berg et al. (1998), which determines reaction rates by fitting observed
concentrations to a diffusion-reaction equation that neglects the
presence of water flow within sediments. However, hyporheic flow is
extremely common in streambeds, where solute transport is often
controlled by advection rather than diffusion. There is hence a pressing
need to develop new methods that can be applied even to
advection-dominated sediments. This contribution fills this gap by
presenting a novel approach that extends the method proposed by Berg et
al. (1998). This new approach includes the influence of vertical solute
transport by upwelling or downwelling water, and it is this suited to
the typical flow conditions of stream sediments. The code is applied to
vertical profiles of dissolved oxygen from a laboratory flume designed
to mimic the complex flow conditions of real streams. The results show
that it is fundamental to consider water flow to obtain reliable
estimates of reaction rates in streambeds. Berg, P., N.
Risgaard-Petersen, and S. Rysgaard, 1998, Interpretation of measured
concentration profiles in the sediment porewater, Limnology and
Oceanography, 43:1500-1510.
M3 - פוסטר
SP - 15773
ER -