Austin Gentel, Delaware Valley College
Dr. Matt Kuchta, University of Wisconsin-Stout
Introduction:
Background Knowledge:
Methods:
The purpose of our part of the study is to
determine how much phosphorous is naturally
occurring, also known as background
phosphorous, because the amounts are
actually unknown in this area. This poster
describes the flow paths of the water by
determining how much of the water is Preevent or New. Pre-event water is considered
water that was already in the body of water or
in the surrounding soil, whereas new water is
more considered water from runoff and
precipitation. We conducted our study using
Silica, d18O, d2H, and conductivity as our
tracers. Our results are that the stream
channels are mainly made up of pre-event
water, showing that there is a fair amount of
naturally occurring phosphorous. This means
that we cannot ignore the background
phosphorous when looking at the big picture.
 Silica- in the water is a result of the water striping the silica from the rocks and soil
 Electric Conductivity - is the measure of how a material accommodates the transport of
electric charge and is determined by the number of dissolved ions in the water.
 d18O- is an ion of water that is heavier because the Oxygen has a two extra neutrons
leading to it condensing into precipitation faster than d2H
 d2H- is another form of water that is much lighter than d18O, making it able to vaporize
and take long to condense for precipitation.
 Discharge- is the amount of water flowing past a certain location, in our case the creeks
To determine the concentration or value of the tracer, we
conducted different tests on the water samples:
 Conductivity’s value was determined by placing a probe
into the water sample and giving us a quick reading.
 Silica was determined by mixing various chemicals such as
HCl, Ammonium Molybdate, and Oxalic Acid. To give the
water sample a yellow color which allowed the UV-Vis
Spectrophotometer called Genesys to determine the
absorption and intern the concentration of Silica
 Water Isotope values were obtained by sending the
samples off to DR. Anne Jefferson’s lab of the Dept. of
Geology at Kent State University
Water Isotope Values
-40.0
Jarvis Hall Rain
South Menomonie
Rain
18MC Rain
-45.0
April Stream Values
-50.0
TICR Rain
After determining the concentration of each tracer, we were
able to plug these values along with the discharge values into
the Mass Balance Equation to determine the percent of new
and pre-event water.
∂2H
18MC Event
-55.0
TICR Event
-60.0
-65.0
-70.0
-10.50
𝑄𝑛 = 𝑄𝑡 ∗
Mass Balance Equation:
-10.00
-9.50
-9.00
-8.50
-8.00
-7.50
-7.00
-6.50
-6.00
𝐶𝑡 −𝐶𝑜
(
)
𝐶𝑛 −𝐶𝑜
∂18O
%New Water IHS using ∂18O, ∂2H, Silica, and Conductivity
18Mile Creek
35
25.0
-10.50
%New d18O
30
20.0
%New d2H
-10.00
25
15
10
15.0
Total Q
-9.50
∂18O
Q (cfs)
20
%New Silica
Pre-Event Water (d18O)
Event Water
%New Conductivity
10.0
-9.00
5.0
"∂18O Samples"
5
-8.50
6/22/2015 0:00
6/22/2015 12:00
6/23/2015 0:00
6/23/2015 12:00
6/24/2015 0:00
6/24/2015 12:00
6/25/2015 0:00
-8.00
Date/Time
Results:
Our data has helped us determine that majority
of the stream channel’s water is pre-event water
because the percent of new water is much lower
than the percent of pre-event water, only about
20-24% of the water is considered new water by
the tracers. This means that most of the waters
composition and make-up is from water seeping
into the creeks from the surrounding soil, with
less from runoff and direct precipitation. Another
result we discovered was that the isotopes
created very clean data set, silica made fairly
clean data set, and conductivity’s data set came
out kind of jumbled.
Implications:
The fact that pre-event water is making
up a majority of the water entering the
system, it means that there is going to be
a fair amount of naturally occurring
phosphorous in the creek. This occasion is
mainly taking place in 18 Mile Creek
because of the surrounding rock
formations, which contains high amounts
of phosphorous, and is located in the
eastern part of the watershed.
6/22/2015 0:00
6/22/2015 12:00
6/23/2015 12:00
6/24/2015 0:00
6/25/2015 0:00
Conductivity vs. Discharge (size of bubble =
TSS)
Silica vs. Discharge (size of bubble = TSS)
35
35
35
Rising Limb
Rising Limb
30
30
Falling Limb
20
15
10
30
Falling Limb
25
20
15
10
25
20
15
Rising Limb
10
5
5
5
0
-10.10
0
0
-9.90
6/24/2015 12:00
Date/Time
∂18O vs. Discharge (size of bubble = TSS)
25
6/23/2015 0:00
-5.0
Discharge (cfs)
6/21/2015 12:00
0.0
6/21/2015 12:00
Discharge (cfs)
0
6/21/2015 0:00
-5
Discharge (cfs)
∂18O Stream Samples 4/17
-9.70
-9.50
∂18O
-9.30
10
12
14
16
Silica (mg/L)
18
20
Falling Limb
120
130
140
150
160
Conductivity (µS/cm)
References:
Klaus, J., and J.j. Mcdonnell. "Hydrograph Separation Using Stable Isotopes: Review and Evaluation." Journal of Hydrology 505 (2013): 47-64. Print.
Acknowledgments: Andy Twiss, Jonah Sorell, Dr. Anne Jefferson’s Lab of the
Dept. of Geology at Kent State University
Pellerin, Brian A., Wilfred M. Wollheim, Xiahong Feng, and Charles J. Vörösmarty. "The Application of Electrical Conductivity as a Tracer for Hydrograph Separation in Urban Catchments." Hydrol.
Process. Hydrological Processes 22.12 (2008): 1810-818. Print.
Ritter, Michael E. The Physical Environment: an Introduction to Physical Geography. 07/31/15. http://www.earthonlinemedia.com/ebooks/tpe_3e/title_page.html
This work supported by National Science
Foundation SMA grant #135738