Environmental Engineering Reference
In-Depth Information
Fig. 3.33 Application of bromide tracer in a prairie wetland (Parsons et al.
2004
). To ensure even
distribution of tracer, the tracer solution was slowly released to the wetland from a boat moving
around the wetland (Photo printed with kind permission of
©
David Parsons 2012. All rights
reserved)
Once the balance equations are written for measured values, they can be
implemented in a spreadsheet or a simple computer program to compute desired
components. For example, Choi and Harvey (
2000
) used chloride to quantify
groundwater inflow and outflow in constructed wetlands in Florida, U.S.A. Parsons
et al. (
2004
) used bromide to quantify evaporation and groundwater outflow in a
prairie wetland in Saskatchewan, Canada.
3.10.2 Remarks on Water Sample Collection
Successful application of the mass-balance approach depends on how well the
simplifying assumptions are satisfied and how well all the concentration terms are
represented by measured values. If a single value of
C
W
is used to represent
the whole wetland pond, it is important to verify that the pond is well mixed by
periodically sampling and analyzing water from different locations and depths. If an
artificial tracer is applied to a pond, it needs to be applied evenly in the entire pond
area to ensure a uniform initial concentration (Fig.
3.33
). Samples near the water
surface can be collected by simply submerging a clean bottle in water. Deeper
samples need to be collected using a tube with an intake at the sampling depth
connected to a pump or plastic syringe, or using a van Dorn, Kemmerer, or other
type of sampler (see Ward and Harr
1990
). In water up to approximately 1 m in
