Health of the Elbow River, AB in light
of increasing urbanization - Total
suspended solids and sediment
associated contaminants.
--Bryan Jang, Tyler Lingnau, Alyssa Thompson, Melanie Trepanier
1
Table of Contents
Abstract……………………………………………………………………………………………...………………………..3
Introduction…………………………………………………………………………………………….…………...………4
Materials and Methods………………………………………………………………………………………………...7
Results………………………………………………………………………………………….……………………...……..10
Discussion……………………………………………………………………………………….…………………...……..18
Conclusions and Recommendations…………………………………..………………………………...……..21
Acknowledgements……………………………………………………………………………………………...……..22
Citations……………..…………………………………………………………………………………………..…...……..23
Appendices……………………………………………………………………………………..…………………...……..25
List of Figures
Figure 1………………..……………………………………………………………………………………………...……….7
Figure 2………………..……………………………………………………………………………………………...………10
Figure 3………………..……………………………………………………………………………………………...………11
Figure 4………………..……………………………………………………………………………………………...………12
Figure 5………………..……………………………………………………………………………………………...………13
Figure 6………………..……………………………………………………………………………………………...………15
Figure 7………………………………………………………………………………………………………………………...17
Table 1………………..……………………………………………………………………………………..………...………14
Table 2………………..……………………………………………………………………………………..………...………16
2
Abstract:
Clean drinking water is a concern for many cities and countries around the world. The
policy makers that implement regulations for watershed protection rely heavily on the
observations and data obtained by researchers through prolonged, continuous sampling due to
the highly variable and unpredictable nature of rivers. Growing urbanization has put a much
greater demand on small rivers such as the Elbow River in Alberta, Canada. Because a
decrease in water quality will affect one third of the residents of Calgary, this study aims to
add to the scientific data surrounding the effects that increased nutrient loading, total
suspended solids (TSS) and metal accumulation can have as a consequence of increasing land
development. By air lift sediment sampling, fine grain sediments were removed from the
riverbed and analyzed for limiting nutrients (carbon, nitrogen, and phosphorous) and heavy
metals (arsenic, lead, copper, zinc and nickel). River water was also collected in order to
document TSS levels in low flow conditions. This study presents metal concentrations
(arsenic and nickel) that exceed environmental protection levels. Nitrogen, phosphorus and
TSS levels all show a spatial trend and increase with proximity to the city of Calgary. TSS
levels recorded at sites closest to the city since 1982 show a temporal trend where TSS
concentrations increase with time. The results of the study suggest that increasing land use
has negative effects to overall water quality, which is of great concern to the health of
humans and aquatic life. With a growing population comes the need for more procedures to
be put in place to protect the watershed. More detailed sampling of this type along the length
of the river is required to enable policy makers to develop these procedures.
3
Introduction:
The health and protection of river ecosystems is intensely studied, as the presence of
fresh, clean, water is essential to human survival and it is of social and economic value to our
cities. The City of Calgary, Alberta, relies on the Elbow River for nearly half of its water
supply and one sixth of Albertans use it as a drinking water source (City of Calgary, 2015;
Sosiak & Dixon, 2004). Aquatic ecosystems, such as the Elbow River, are comprised of
many complex networks of interactions between species and abiotic variables, which connect
in intricate ways to form a delicate balance within food webs.
The amount of TSS in a river system has been identified as a major parameter of
water health and is a primary economic cost with respect to the efficiency of operation in
water treatment plants (Sosiak & Dixon, 2004). High levels of TSS can negatively affect fish,
invertebrates and aquatic organisms depending on both the quantity of particles and duration
of exposure (Newcombe & Jensen, 1996). High levels of TSS increase the turbidity of the
water and limit the photosynthetic ability of local periphyton, phytoplankton, and
macrophytes (Bilotta & Brazier, 2008). This reduction in primary productivity can impose
drastic effects on higher trophic levels as energy and biomass input can be greatly reduced.
High TSS levels can also clog and abrade the delicate gill structures in fish and feeding
apparatuses in some invertebrates (Newcombe & Jensen, 1996). Perhaps one of the most
intensely studied effects of TSS, which also has potential impacts to Calgary’s economy
through sport fishing, is the negative effects on Salmonid fish species’ reproduction. As the
settling of fine sediment particles onto fish eggs can lead to suffocation by preventing
adequate oxygen exchange with the water, and poisoning through the diffusion of
exchangeable ions and metals across the egg membrane (Bilotta & Brazier, 2008).
Another key function of TSS and river bed sediments affecting water quality is their
ability to interact with nutrients such as phosphorus (P) and nitrogen (N); two of the key
limiting nutrients to algal and cyanobacterial growth in aquatic ecosystems. Because nutrients
and metals such as arsenic (As), copper (Cu), iron (Fe), nickel (Ni) and zinc (Zn) can be
sequestered in suspended particles and river sediments, there is potential for long lasting
effects on the environment that have thus-far been difficult to predict. The most relevant form
of P that can be found in aquatic systems is the portion that is biologically available classified
as soluble reactive phosphorus (SRP), and the total dissolved phosphorous (TDP) that is
freely available in the water column (House, 2003). Some key ways that P can be exchanged
between the water column and sediment are: through biological processes like bacterial
4
activity or macrophyte growth, chemical factors (dissolved oxygen (DO), pH, and ion metal
content), and physical factors that lead to the resuspension of sediments (House, 2003;
Hayakawa et al., 2015).
There has been a significant amount of research in identifying the various ways that
phosphate (PO4+) interacts with sediment, most importantly being the correlations between
the clay content of the river sediments and the increased binding ability of P to fine particles
< 64μm (House and Warwick, 1999; House, 2003; Bowes, 2003). The dominant minerals
found in the coarse grained particles of the Elbow River are quartz, calcite and dolomite
which are conductively neutral, while the interactive clay component is predominantly illite
and kaolinite (Brinkmann & Lehmann, 1989). Both clays have a very high binding affinity
for metals and nutrients. A positive correlation is typical between high concentrations of fine
sediment to organics and metals (Cu, Zn, As, Ni, Pb) and the sorption of P to the sediment
particles (House & Warwick, 1999; House, 2003). These properties cause the sequestering of
P in sediments in well oxygenated conditions, but in the summer when river flow decreases
and temperature increases, hypoxic conditions near the river bed sediments can cause the Fe
bound P to release SRP (or PO4+) into the water column (House & Warwick, 1999; House,
2003; Bowes, 2003). This is because low oxygen conditions near the river-bed allow Fe ions
to be released from the sediments while simultaneously releasing their associated P, alowsing
SRP to diffuse across the water-sediment interface (Hayakawa et al., 2015). This creates an
internal source of nutrient loading in the river system which contributes to summer algal and
toxic cyanobacteria blooms, and furthers anoxic conditions and fish deaths following
decomposition (House, 2003; Hayakawa et al., 2015).
The impact of land use on the percentage of nutrients bound to suspended particles
was studied in the Swale River in 2003. More than 85% of the P in the river was introduced
in the lowlands due to P inputs like intense agriculture, urban runoff and treated sewage
(Bowes, 2003). The lowland region - with the most P inputs, highest SRP content and highest
quantity of fine sediments – was the only region to experience major impacts in P export due
to season (Bowes, 2003). This is because sorption of P to suspended particles was almost
instantaneous compared to the sequestering of P in the coarser grained upland bed sediments,
causing lower P exports in the summer (Bowes, 2003; House, 2003). According to this
principle, storm events that remobilize sediment can therefore increase the rate of P diffusion
from the sediment to the water column.
In 2015, interactions of both N and P with river sediment were examined at the
mouths of five rivers flowing into Lake Hachiro in Japan. The main findings were that while
5
the concentration of P in sediments varied temporally and spatially, there were no variations
in N (nitrate= NO3-, nitrite= NO2-, and ammonium = NH4+) following this pattern, although it
did decrease during the anoxic conditions of the summer due to increased denitrification by
microbes (Hayakawa et al., 2015). Therefore, during times of low oxygen, the dissolved and
sediment bound N decreased while SRP released from Fe-P increased, lowering the N: SRP
ratio and resulting in large algal blooms (Hayakawa et al., 2015). Only very current research
can be found on the interaction of both N and P with sediments as most research was focused
only on P. It is also less clear as to the net effect of river bed sediments versus suspended
particles on these nutrients, because the water-sediment interface has more complicated
interactions due to the presence of algal biofilms, and decomposition processes.
Anthropogenic factors such as stormwater outfalls and urban runoff have been shown
to have significant influence on aquatic systems. This influence is due to the large amount of
erosion from alteration of natural areas, the chemical application that is common throughout
urban and agricultural regions and from aging sewage infrastructure which can leak waste in
the ground (Sercu et al., 2011). Land use management has enabled humans to divert
untreated stormwater into rivers through stormwater outfalls, which increases the effects of
urbanization on the health of the river by adding clay or silt particles, metals and nutrients
directly to a river (Martínez-Carreras et al., 2012). Storm water outfalls present concentrated
additions of Cu, Zn, and Ni along with nutrients to aquatic systems as they collect runoff
from the proximal urban environment and are typically left untreated (Ellis & Revitt, 1982).
When combined with nutrient loading, this point-source loading can result in a significant
decline in the health of the system following such inputs (Ellis & Hvitved-Jacobsen, 1996).
Due to the dynamic chemical interactions that proceed in a river system, it is both
important and relevant to study the water chemistry, TSS levels, as well as the sediment
composition and associated ions and minerals of the Elbow River. These factors are of great
importance as they offer insight into the health of the system and allow trends in aquatic
fauna to be properly identified and mitigated if needed. This study aims to acquire more data
to distinguish the effects that land use has on watersheds while documenting the significant
effects seen in water quality parameters. This study will address gaps in water quality data
along the Elbow River Watershed to inform the public on the effects of increasing
urbanization on decreasing water quality (Sosiak & Dixon, 2006). We intend to distinguish
these indicators as anthropogenic by comparing our data with the isotopic ranges of N for
common anthropogenic activities such as fertilizer applications (Rock & Mayer, 2003).
6
The focus of this research will be the importance of anthropogenic activities as they
affect TSS loading, and nutrient and toxin storage in the Elbow River sediments. We expect
that TSS, nutrient and metal levels will increase in the Elbow River as it approaches the City
of Calgary as a result of increased land use and development. Using an air lift sampler for
sediment collection, this study was able to quantify major ions, metals and nutrients through
various analytical techniques so as to characterize each of the sites along the Elbow River.
These parameters were chosen as they can be potentially correlated to the anthropogenic
activities along the length of the watershed (Gratsby & Hucheon, 1998 and Martínez-Carreras
et al., 2012). By evaluating the organic and inorganic fractions of material associated with
river sediment, we were able to develop spatial and temporal trends to narrow down potential
problem areas for nutrient and metal loading along the river. These problem areas are
presented from upstream to downstream so that policymakers can target areas based on the
importance of the aquatic life present and downstream use of water.
7
Materials and Methods:
The data for this study were collected along the upstream reach of the Elbow River
from the City of Calgary, Alberta. Samples were taken at: Redwood Meadows, Highway 22,
Twin Bridges, the downstream edge of Griffith Woods in Discovery Ridge, and Sarcee
Bridge on October 24th, 2015 (Figure
1).
Figure 1. Elbow River Watershed sampling locations including: Redwood Meadows,
Highway 22 Bridge, Twin Bridges, Discovery Ridge and Sarcee Bridge. Some locations had
multiple sites, and the site ID’s used on any subsequent graphs are: RMUS (Redwood
Meadows Upstream of storm outfall), RMDS (Redwood Meadows Downstream of storm
outfall), HWY-22 (Highway 22 Bridge), TB (Twin Bridges), DRUS (Discovery Ridge
Upstream of storm outfall), Base Flow (Base Flow from storm outfall), DRDS (Discovery
Ridge Downstream of storm outfall), SGE (Sarcee Grey Eagle Bridge).
Water parameters such as pH, temperature, electrical conductivity (EC) and DO were
taken in the field using standard instruments. Water samples and river bed samples were
collected at each site for further water chemistry, mineralogy, metal nutrient and TSS
analysis. A stormwater outfall was present at the Discovery Ridge site and a water sample
was collected to compare the base flow ions with the typical ion concentration in the river.
8
An air-lift sampler from Alberta Environment was used for riverbed sediment
collection, as the cobble riverbed of the Elbow River limits the available sampling
techniques. At each site, five 23 L buckets of river sediment slurry were collected by
directing a stream of compressed nitrogen gas (20-45 psi) into the riverbed to lift sediment as
deep as 2 cm. The upwelling water was pre-filtered through an 80μm mesh at the outlet pipe
(Alberta Environment, 2006). The sampler was moved around the site until the buckets were
filled to ensure representative sampling. After a 24 hour settling period, the clear supernatant
was siphoned off. The remaining sediment was transferred into glass jars and refrigerated for
an additional 24 hours before siphoning supernatant off again. TSS was calculated by
filtering 16 L of water from each sample location through a filter with a pore size of 1.5μm.
The material that accumulated on the filter paper was dried at 70°C for 2 hours and the
material dry weight was recorded and converted to mg/L.
The riverbed sediment was analyzed for exchangeable nutrients, including exNO3-,
exNH4+ and exPO4+. Sediment exPO4+ was determined by combining ~4.5 g of sediment in
50 mL of 0.5M NaHCO3 for the extraction. The exNH4+ was determined by combining ~2.5
g of sediment with 20 mL of 2M KCl for extraction, and exNO3- was extracted with 20 mL of
DI water. These samples were prepared further by filtering sediments to < 64 μm from each
sample location. The sample slurry was then agitated at 150 rpm for 1 hour. The slurry was
filtered and the extracted ion solutions were analyzed through spectrophotometry by plotting
absorbance readings on a calibration curve to determine concentrations which were then
converted to μg/g.
River water samples were analyzed for various chemical properties including
alkalinity, ion concentrations of magnesium (Mg2+), calcium (Ca2+), chloride (Cl-), fluoride
(F-) sodium (Na+) potassium (K+) and sulfate (SO42-) and nutrient concentrations of NO3-,
NH4+, TDP and total phosphorous (TP). Major ions were analyzed on supernatant by ion
chromatography.
Organic content of the river sediment was estimated using loss on ignition (LOI) by placing
three grams of finely ground sediment into crucibles which were heated to 550°C for 4 hours.
The loss of weight was attributed to organic matter and was used to calculate a % which was
then converted into mg/g.
The C and N isotope ratios were measured by Continuous-Flow Isotope Ratio Mass
Spectrometry and was performed on the sediment samples from each sit at the University of
Calgary Stable Isotope Laboratory (ISL-AGG, a Finnigan Mat Delta+XL mass spectrometer
interfaced with a Costech 4010 elemental analyzer). The percent of total C and N, as well as
9
the values of 13 δ C‰ and 15δ N‰ in the sediment samples were determined. The percentages
of total C and N were converted into mg/g.
The river sediment was analyzed by X-ray fluorescence spectrometry (XRF; XRF
Solutions) for heavy metal content, and using X-ray diffraction spectrometry (XRD) to assess
clay mineralogy. The weight percentage of Al, Fe, Ca, Cr, Ni, Cu, Zn, P, As and Pb were
converted to ppm in order to compare the concentrations to sediment standards in water
quality guidelines for sediment in rivers (ESRD, 2014). This study used As, Fe and Ni as
anthropogenic indicators and excludes analysis of all other metals listed. The XRD was used
to determine the bulk composition of minerals found in the sediments (illite, kaolinite, quartz,
calcite, dolomite, plagioclase, K-feldspar and pyrite).
The study TSS concentrations were collated with TSS data provided by the City of
Calgary for the month of October at Twin Bridges, Hwy-22 and Sarcee, but the study data
compared the levels found at Redwood Meadows in place of those found at Bragg Creek by
the City. Exchangeable nutrients and water chemistry data collected from each of the seven
sites were plotted as a function of distance from Elbow Lake (the water body representing the
headwaters of the Elbow River Watershed) to explore spatial trends. The TSS fluxes (mg/s)
were calculated as the product of concentration (mg/L) and river discharge (m3/s) for the City
of Calgary data, which encompasses data from 1982-2014, was plotted as a function of Julian
Day to evaluate year-long trends and to determine how discharge influences TSS
concentration (Figure 4). The sediment content of C and N (mg/g) from the isotope lab, as
well and the sediment content of P (mg/g) from the XRF lab were graphed as a function of
organic matter content (mg/g) to explore how these biologically important macronutrients are
stored in the Elbow River sediments.
Statistical tests were run to determine the significance of apparent trends in the data.
A seasonal Mann-Kendall test was run to evaluate significant monotonic trends in the City of
Calgary’s TSS concentration data over the years 1982-2015. The Spearman’s Rank
Correlation Test was run for the parameters of Fe sediment content and P sediment content.
10
Results:
The TSS in the seven sites measured along the Elbow River at first showed decreasing
concentration with flow distance until the two Discovery Ridge sites and Sarcee Bridge site,
at which point there was a sharp increase in TSS (Figure 2).
Figure 2. The concentration of TSS in mg/L from the study sites along the Elbow River on
October 24, 2015. The light blue markers represent the sites that are directly downstream of a
storm water outfall.
The City’s TSS concentration data for the month of October from 2005 to 2015 also
showed a similar spatial trend of sharply increasing TSS at the Sarcee Bridge site closest to
the City (Figure 3). The graph showed that TSS has generally increased at all sites over time,
and this was supported by the results of the Seasonal Mann-Kendall test (Appendix B, Table
I). No correlation was found between P and Ca or P and aluminum.
The TSS flux by Julian Day shows the TSS flux from 2002 to 2014 for the Sarcee
Bridge site (Figure 4a). The graph of 2014 data is generally higher than the other series,
except for peak flow season. The 2008-2010 data is also generally higher than the 2002-2006
data, except for peak flow season. During peak flow season, there is not a very strong
temporal trend and it was unclear as to which years had the highest flux because the series
were more homogenized (Figure 4a). The TSS flux peaks in June but otherwise remains
similar for the rest of the year (Figure 4b). Even having taken into account seasonal
11
discharge, the trend of the Sarcee Bridge series (the site closest to the City of Calgary) shows
a higher TSS flux than the other sites, which are much more homogenous (Figure 4b).
Log scale Concentration of TSS (mg/L)
Log scale Concentration of TSS (mg/L)
Figure 3. Concentration (Log10) of total suspended solids at all sites along the Elbow River
in October from 2006 to 2015 (City’s Data).
12
Figure 4. The TSS flux calculated using historical data from the City of Calgary from1982 to
2014 plotted against Julian Day at: a) Sarcee Bridge site in 2002, 2006, 2008 and 2010 and b)
Bragg Creek, Hwy-22, Twin Bridges, and Sarcee Bridge.
13
The exchangeable nutrients (ex NO3-, ex NH4+ and ex PO43-) measured on the river
sediments from each study site shows a trend of increasing ex PO43- bound to the sediment as
the river approaches the City, but the concentration of exchangeable Total Nitrogen (ex TN,
the sum of ex NO3- and ex NH4+) does not show as strong an increase with distance from
Elbow Lake (Figure 5). While the sediments showed a spatial trend of increasing nutrients
with distance from Elbow Lake, the dissolved nutrients did not experience this trend.
Figure 5. Concentration of exchangeable nutrients (μg/g) in fine river sediment and sludge at
all seven sites along the Elbow River on October 24, 2015.
Most of the proportions of δ15N isotope found in the sediments are below 1‰,
however, the four sites closest to the City (TB, DRUS, DRDS and SGE) all had levels above
1‰ (Table 1). This indicates a spatial trend of increasing δ15N with distance from Elbow
Lake. The two sites with the highest abundances of δ15N were in Discovery Ridge, and the
Redwood Meadows site downstream of the storm water outfall (RMDS) had the most
elevated proportion overall (3.29‰). There is no obvious spatial trend in the proportions of
δ13C isotope found in the sediment samples, however once again Twin Bridges and the two
Discovery Ridge sites had similar values.
14
Table 1. Exchangeable nutrients, organic matter and isotope ratios found in sediments at
study sites along the Elbow River. Fine sediment samples (collected using the airlift sampler)
and sludge samples (scooped by hand into a bucket) were collected on October 24, 2015. US
and DS represent upstream and downstream of storm water outlets, respectively. The
abbreviation “n.a.” means the data is not available due to sediment shortage and “n.d.” means
the concentration was not detectable. The detection limit for NO3 is 0.7µg; limit for NH4+ is
0.1µg; limit for PO4 is 1µg.
Site
OM
(mg/g)
C
(mg/g)
13
δC
(‰)
N
(mg/g)
Ex
NO3(µg/g)
Ex
NH4+
(µg/g)
Ex TN
(µg/g)
15
δN
(‰)
P
(mg/g)
PO43(µg/g)
RMUS
38.7
39.3
-4.6
0.67
n.a.
10.44
10.44
0.53
0.44
1.58
RMUS
sludge
50.0
42.3
-6.0
1.11
3.64
4.34
7.98
0.7
0.42
n.d.
RMDS
71.7
49.1
-9.8
1.37
n.a.
6.51
6.51
-0.05
0.32
n.d.
RMDS
sludge
41.5
41.3
-4.0
0.78
1.55
9.46
11.01
0.7
0.50
1.91
Hwy22
62.8
44.0
-8.6
1.55
n.a.
11.87
11.87
0.49
0.33
2.48
Twin
Bridge
s
56.6
60.8
-6.5
1.58
2.83
6.83
9.66
1.34
0.36
3.24
DRUS
61.2
63.3
-7.6
1.75
1.67
5.52
7.19
2.11
0.55
6
DRDS
56.5
65.4
-6.7
1.55
2.53
6.22
8.75
3.29
0.50
4.52
Sarcee
Bridge
sludge
35.4
46.0
-3.8
0.61
2.06
9.07
11.13
1.59
0.59
n.d
The C, N, and P content in the sediment were plotted as a function of organic matter
content and revealed trends of how these nutrients are stored in the Elbow River sediments
(Figure 6). The sediment samples at each of the sites are above the 60% C line (which
denotes the typical percentage of C in organic matter) and formed a cloud of data points,
rather than a line (Figure 6a). The sediment samples at all seven sites show a linear trend of N
with organic matter (Figure 6b), however P did not appear to have a strong correlation with
organic matter (Figure 6c). A further statistical analysis was done to assess the precipitation
of P with metals, and Spearman’s Rank Correlation Test showed a strong negative correlation
between P and Fe (ρ= -0.73, 2 sided p-value < α0.05).
15
Figure 6. Nutrient concentrations in mg/g as a function of organic matter content from the
study sites along the Elbow River from October 24, 2015. Figure a) total nitrogen content
with a line of best fit, (b) total phosphorous content, and (c) total carbon with a 60% trend
line that represents the typical percentage of C in organic matter.
The general composition of the sediment tested using XRD characterized the samples
as being 40% quartz, 25% dolomite, 15% calcite, 20% clays (mostly illite), and containing
trace amounts of pyrite (<1%). Arsenic and Ni were above the recommended concentrations
in the soil at all of the sites (Appendix B: Table IV). There is a trend of decreasing metal
content with distance from Elbow Lake for Ni, As, Cu, and Zn, however there is no strong
spatial trend for Pb. Metals concentrations were evaluated based on Alberta guidelines and
the comparison showed the levels of As and Ni are in excess of the lowest effects levels for
the protection of aquatic life (Figure 7).
16
Figure 7. Spatial trend of metals (ppm) from the study sites along the Elbow River from
October 24, 2015. (a) Concentrations of nickel with the red line indicating the Alberta
guideline for sediment concentrations (b) Concentrations of arsenic with the red line
indicating the Alberta guideline for sediment concentrations (c) Iron, copper, zinc and lead
content, which were all below the Alberta guideline from the “Guidelines for the Protection
of Aquatic Life for Sediments and Surface Waters”.
Analysis of the chemical properties including nutrients and ions of water samples
collected from the study sites along the Elbow River (Mg2+, Ca2+, F-, Cl-, Na+, K+, SO42-,
NO3-, NH4+, TDP, TP, EC, DO, pH and alkalinity) showed no significant spatial trend with
distance from the headwaters (Appendix A: Figures I-III; Appendix B: Table II). The base
flow sampled from the storm outfall at Discovery Ridge showed a large peak in Mg2+, Ca2+,
Cl-, Na+, K+, NO3-, TDP, TP, EC, and alkalinity. A large decrease was seen in SO42- and DO,
while there was no change in trend for pH, NH4+, and F- (Appendix A: Figures I-II). These
increases or decreases in concentration did not persist downstream. Temperature showed an
increasing spatial trend with distance from the headwaters, with a particularly large peak at
the base-flow site.
17
Discussion
The TSS in the seven sites measured along the Elbow River initially decreased in
concentration until the two Discovery Ridge sites and Sarcee Bridge site, at which point there
was a sharp increase. As these sites are closest to the City, we conclude that land use in the
surrounding area – in this case urbanization – played a role in the increase of TSS. This
conclusion was further supported by the City’s data, which also showed a similar trend of
sharply increasing TSS at the sites closest to the City (ie. Sarcee Bridge) (Sosiak and Dixon,
2004). October TSS concentrations have generally increased at all sites over time (Figure 3,
Appendix B, Table 1). Since the Calgary region has experienced an increase in urbanization
over time, this temporal trend of increasing TSS suggests increased urbanization leads to an
increase in TSS (cf. ENSC 502 - Land Use). The TSS mass flux also experienced an increase
over time (Figure 4), likely due to anthropogenic impacts. Additionally, the TSS mass flux
experiences seasonal trends, as peaks were observed in June at all sites using historical data
(Sosiak & Dixon, 2004). This is likely due to higher river discharge caused by mountain
snowmelt and spring runoff events. Peak TSS concentrations also coincided with peak river
discharges during these spring runoff events. Possible sources for increased TSS include bank
erosion, the resuspension of bed material, and non-point agricultural runoff (Sosiak & Dixon,
2004).
The concentrations of nutrients bound to river sediments increased with distance from
Elbow Lake. The gradual slope of the spatial trends observed in sediment bound nutrients
indicates a non-point source of N and P along the Elbow River, as compounding nutrient
inputs from different land uses along the river contribute to the increase in N, PO4+, and total
nutrients bound to the sediment. Common land uses surrounding the Elbow River include
agriculture, livestock grazing, and recreational activities like golfing (cf. ENSC 502 Land
Use). All of these land uses contribute nutrients to the watershed through the addition of
fertilizers or leaching from animal waste, which can then bind to TSS and river sediments
(Rock & Mayer, 2005). The data show levels of total nutrients increasing with proximity to
the City, especially at Discovery Ridge, which is within an urban community.
The opposite trend was seen with respect to the nutrient concentrations found in the
water, which did not vary with increased distance from the headwaters. The water chemistry
parameters measured did not indicate that storm outfalls influenced the chemistry of the river
downstream, even though the water chemistry of the base flow site was much richer in ions
and nutrients than the typical river water chemistry of the Elbow River. This indicates that the
18
volume of the river is sufficiently diluting the effects of the storm water outfalls, which
limited the influence of the base flow on the water chemistry of the river at the time of
sampling. However, the study data were collected in October, and the effects of the storm
water outfalls may be influenced by seasonal trends, storms and runoff. Therefore, obtaining
more data during the spring and summer, when precipitation is higher around Calgary, would
be necessary to verify this pattern.
Nutrients have to potential to be stored in different ways due to varying reactability
and solubility in water, and this phenomenon was explored by examining the extent that
nutrients are stored in the organic matter of the sediments. The sediment samples at each of
the sites were above the 60% C line, indicating that there was C from all sites was
predominantly unavailable inorganic C and was tightly bound to the sediments. The sediment
samples at the seven sites showed an approximately linear trend of N with organic matter,
indicating that most of the N was stored in the organic matter bound to the sediments. The
sediment samples at the seven sites showed no obvious trend between organic matter content
and P content. This indicates that organic matter is not the primary form of storage for P in
sediment. The strong negative decreasing trend from the Spearman’s Rank Correlation Test
(which compared the Fe and P content in the sediments) could indicate that P is precipitating
out of the water column with Fe under the oxic conditions in the river and forming insoluble
compounds that bind with the sediments of the river (House & Warwick, 1999).
The δ15N at each site gives an indication of the nutrients’ source. The δ15N (‰) of the
sediment in the seven sites initially decreased between both Redwood Meadows sites to
Highway 22, and generally increased with flow distance from Highway 22 to Discovery
Ridge (Table 1). The isotopic composition of NO3- allows the anthropogenic sources of
nitrate to be identified, as each source is characterized by a unique isotopic signature (Rock &
Mayer, 2006). The most relevant anthropogenic sources of nitrate include waste effluent and
synthetic fertilizers, with waste effluent introducing higher δ15N compared to synthetic
fertilizers (Rock & Mayer, 2003). Based on land use changes along the Elbow River, it can
be seen that there is more urban development closer to the City, starting from Highway 22 to
Discovery Ridge. An increase in urban land use and decrease in agricultural land use along
the Elbow River is a possible explanation for the increasing trend in δ15N, as this could cause
higher amounts of waste effluent and increased fertilizer inputs from urban communities or
golf courses (Rock & Mayer, 2003). The influence of the storm outfall can also be seen in the
sharp increase between the upstream and downstream Discovery Ridge sites. The increase at
the downstream site indicates that the influence of the nearby urban community significantly
19
increased the δ15N input to the Elbow River. Based on the trend of increasing δ15N along the
Elbow River, it can be seen that nitrogen inputs have a significant dependence on land use
change and anthropogenic impacts (Rock and Mayer, 2003; Rock and Mayer, 2006).
The decreasing heavy metal concentrations from Elbow Lake towards the city
indicated a source located in headwaters of the watershed. Land use activities such as coal
mining and natural gas extraction occurred at Moose Mountain in the 19th and 20th centuries
(BraggCreek.ca). This mountain is located just to the west of Bragg Creek, and is joined to
the Elbow River through Canyon Creek which is a tributary that runs the length of the
mountain. In the 1890’s a prospector removed thousands of tons of coal, then in 1913 the first
wells were dug for oil and gas (BraggCreek.ca). Currently, there is a natural gas pumping
station that has been in operation since 1985 (BraggCreek.ca). Because As is a byproduct of
coal mining, the elevated concentrations found in river sediment could be the relic effects of
resource extraction (Kariel, 1997). As there are also many As containing rocks that occur
naturally, the elevated results may also be a result of ground disturbance in the region due to
the construction of the natural gas pumping station (Chen et al., 2015).
Another potential natural source for the metals seen in the Elbow could be due to the
proximity of the upstream sites to the headwaters and the high rates of chemical weathering
experienced in the region, thereby releasing metals from consolidated sediments. Industries
can be another major source of heavy metals, as there is a logging facility upstream of Bragg
Creek (Spray Lakes Sawmills) and some minor oil and gas companies present in the area
(such as Elbow River oil and gas company) (Álvaro et al., 2016; Chen et al., 2015).
Municipal landfills and unregulated rural disposal sites can also be a large point source for
metals and ions as the materials therein slowly weather due to the reducing conditions,
releasing any bound potential contaminants into surface water that eventually joins any
nearby river (Yusof et al., 2009). This may be a topic for further inspection as the Elbow
River flows relatively close (within 500m) to the landfill for Bragg Creek just to the north
east of Wintergreen Rd and is topographically elevated in comparison to the river (Can.,
1940) resulting in a high potential for effluent leaching. The Elbow also has the potential to
collect contaminants from unsolicited disposals across the large rural area its catchment
comprises. Herbicides and insecticides used in agriculture, as well as trace heavy metals
occurring naturally in the surrounding geology, can contribute heavy metals to river
sediments, and so non-point sources in the surrounding mid reach of the Elbow River
watershed may have contributed to the higher concentrations of metals found in the sediment
(Álvaro et al., 2016). Adsorption of heavy metals to sediment is typically a faster kinetic
20
process than desorption of metals to sediment particles, so the main concern with elevated
levels of metals is to the health of benthic organisms (Oursel et al., 2014). However if the
sediments are resuspended (TSS), this process can be reversed, and the river sediments may
release the bound metals into the Elbow River having even larger reaching effects on the
health of the Elbow River ecosystem (Oursel et al., 2014).
Conclusions
The main conclusions to draw from this paper are:
● Flow is the most predominant influence on TSS, but the increases recorded in October
historically can be attributed to changes in land use.
● The influence of urban development on sediment loading is demonstrated by the
higher δ15N content in the river sediment sites closest to the city, suggesting urban
communities as a source of nutrients in the Elbow River.
● Metal concentrations were more elevated towards the headwaters indicating minimal
influence from the single storm water outfall tested, and of urban drainage. However
the levels of Ni and As that exceed guidelines are a cause for concern and their origins
must be further explored.
● The sediment bound nutrients N and P are stored differently and their increasing trend
can be attributed to non-point source additions along the river, most likely due to
changes in land use near the City.
Acknowledgements:
We extend our gratitude to: N. Taube for overseeing our field and lab work and guidance
along with Dr. C. Ryan, F. Malekani MSc. for use of the ENSC lab and aid in sample
processing, the City of Calgary for access to the water quality records, AEMERA for use of
the Air-lift sampler, Ron Spencer of XRF Solutions and Steve Taylor of the Isotope Science
Laboratory for sediment analyses.
21
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River Swale, Yorkshire, UK, Hydrological Processes, 13, 1103-1115.
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24
Appendix A:
Figure I. Water quality parameters taken in the field at all seven sites along the Elbow River
on October 24, 2015. Outfall and Baseflow indicate the positions of stormwater outfalls with
no baseflow and significant baseflow, respectively. These two stormwater outfalls were also
sampled on October 24, 2015.
25
Figure II. Ions and nutrients from water samples collected at all seven sites along the Elbow
River on October 24, 2015. Baseflow indicates the position of a stormwater outfall with
constant discharge, which was also measured on October 24, 2015.
26
Figure III. Nutrients and alkalinity of water samples from all 7 sites along the Elbow River
on October 24, 2015. Baseflow indicates the position of a stormwater outfall with constant
discharge which was also measured on October 24, 2015.
27
Appendix B:
Table I. Significant monotonic trends for total suspended solids (mg/L) at sites along the
Elbow River using a seasonal Mann-Kendall test on City of Calgary data.
Site
Tau Value
2 sided p-value
Sen or SKT
α = 0.05
0.35
8.54e-06
0.062
Cobble flats
Bragg Creek
0.18
2.40e-03
0
Highway 22
0.26
1.10e-06
0.038
Twin Bridges
0.18
1.80e-04
0.041
Sarcee Bridge
0.19
1.10e-02
0.81
Table II. Water chemistry grab samples for all study locations along the Elbow River. Water
samples were collected on October 24, 2015. US and DS represent upstream and downstream
of stormwater outfalls, respectively. The abbreviation “n.a.” means the data is not available
and “n.d.” means the concentration was not detectable. The detection limit for Total
Dissolved Phosphate (TDP) and Total Phosphate (TP) is 7µg/L. The detection limit for NH4+
is 0.02mg/L. The detection limit for all ions measured with Ion Chromatography (Na, K, Mg,
Ca, F, and Cl) is 0.1mg/L. All variables are measured in mg/L unless otherwise noted.
Variable
Redwood Redwood Highway Twin
Discovery Discovery Discovery Sarcee
US
DS
22
Bridges US
Base
DS
Bridge
Flow
7.9
8.41
7.98
8.3
8.25
8.18
8.22
8.27
pH
Dissolved
Oxygen
11.7
11.66
11.41
10.95
10.87
9.6
10.5
10.94
Electrical
Conductivity
0.415
0.382
0.421
0.408
0.426
0.844
0.689
0.465
Temperature
(°C)
2.9
3
4
6.6
5.5
8.2
6.9
6.4
Total
Dissolved
Phosphate
n.d.
n.d.
n.d.
n.d.
n.d.
1.20
n.d.
n.d.
Total
Phosphate
NH4+
n.d.
n.d.
n.d.
n.d.
n.d.
1.58
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
Alkalinity
142
133.5
133.5
138.5
150.5
274
157
156.5
28
Sodium
3.30
1.92
1.94
2.64
3.46
21.68
3.43
3.42
Potassium
0.99
0.77
0.66
1.00
1.11
14.96
1.06
0.97
Magnesium
17.92
16.82
16.84
17.39
18.41
41.77
18.43
18.33
Calcium
62.74
57.77
58.28
61.11
63.65
86.43
63.27
63.17
Fluoride
0.20
0.20
0.20
0.27
0.19
0.16
0.20
0.19
Chloride
0.71
0.81
0.75
1.38
2.07
71.22
2.71
2.80
Nitrate
0.10
0.10
0.10
0.08
0.11
0.83
0.12
0.12
Sulfate
64.69
64.77
64.49
64.23
64.17
44.99
63.74
63.75
TSS
1.68
1.37
1.22
1.08
2.92
n.a
2.59
3.22
Table III. Cl, DO, pH, PO4 and NH4 concentration (mg/L) compared to the Alberta
Guidelines obtained from Alberta ESRD [2014].
Element or Alberta RM RMUS RMDS RMDS Hwy
Twin DRUS DR
compound
Chloride
Ammonium
Guidline US
sludge
sludge
NA
NA
120
0.71
mg/L
mg/L
1.47-
0.1
0.004
0.117
mg/L
8.3-9.5
11.7
mg/L
mg/L
22
DRDS
SGE
base
0.81
0.75
1.38
2.07
71.22
2.71
2.8
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
0.009
0.1
0.01
0.08
0.11
0.006
0.12
0.12
mg/g
mg/g
mg/L
mg/L
mg/L
mg/L
mg/g
mg/L
mg/L
NA
NA
11.66
11.4
10.95
10.87
9.6
10.5
10.9
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
4
mg/L
DO
mg/L
pH
6.5-9
7.9
NA
NA
8.41
7.98
8.3
8.25
8.18
8.22
8.27
Phosphate
0.10-
0.09
NA
NA
0.098
0.098
0.098
0.098
1.58
0.098
0.09
0.20
8
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
8
mg/L
mg/L
mg/L
29
Table IV. The measured values for the physical characteristics, elements and compounds
considered to indicate deterioration due to anthropogenic sources as compared to the
Environmental Quality Guidelines for Alberta Tier 1 Soil Remediation Guidelines obtained
from AEP [2016a]. Items highlighted in red represent values over the acceptable guideline
requirements. All units are in ppm unless otherwise indicated.
Element or Tier 1
RMUS
compound S. R. G.
RMUS RMDS RMDS Hwysludge
sludge
Twin
DRUS
22
DR
DRDS
SGE
base
17
10
5
8
10
10
7
5
n.a.
7
7
120
0.71
n.a.
n.a.
0.81
0.75
1.38
2.07
71.22
2.71
2.8
63
26
22
23
24
30
23
14
n.a.
19
17
Ammoniu
1.47-
0.1
0.004
0.009
0.1
0.012
0.08
0.11
0.006
0.12
0.12
m
0.117
8.3 - 9.5
11
n.a.
n.a.
11.6
11.4
10.9
10.8
9.6
10.5
10.9
pH
6.5 - 9
11
n.a.
n.a.
8.41
7.98
8.3
8.25
8.18
8.22
8.27
Zinc
200
105
80
94
87
114
77
76
n.a.
79
68
0.01
0.0013
0.00
50
31
27
37
33
40
33
20
n.a.
29
24
0.10 –
0.098
n.a.
n.a.
0.098
0.098
0.098
0.098
1.58
0.098
0.098
Arsenic
(ppm)
Chloride
(mg/L)
Copper
(ppm)
(mg/L)
DO
(mg/L)
(ppm)
Lead
(ppm)
Nickel
(ppm)
Phosphate
(mg/L)
0.20
30
Table V. The measured values for the physical characteristics, elements and compounds
considered to indicate deterioration due to anthropogenic sources as compared to the
Environmental Quality Guidelines for Alberta Tier 2 Soil Remediation Guidelines obtained
from AEP [2016b]. Items highlighted in red represent values over the acceptable guideline
requirements. All units are in ppm unless otherwise indicated.
Element or
Tier 2
compound
S.R.G.
Arsenic
0.01
RMUS
RMUS
RMDS RMDS
Hwy-22 TB
DRUS
sludge
sludge
10
5
8
10
10
7
5
250
0.71
n.a.
n.a.
0.81
0.75
1.38
1
26
22
23
24
30
1.47-
0.1
0.004
0.009
0.1
11
n.a.
n.a.
DR
DRDS
SGE
n.a.
7
7
2.07
71.22
2.71
2.8
23
14
n.a.
19
17
0.012
0.08
0.11
0.006
0.12
0.12
11.6
11.4
10.9
10.8
9.6
10.5
10.9
base
(ppm)
Chloride
(mg/L)
Copper
(ppm)
Ammonium
(mg/L)
DO (mg/L)
0.117
8.3 9.5
pH
6.5 - 9
11
n.a.
n.a.
8.41
7.98
8.3
8.25
8.18
8.22
8.27
Zinc (ppm)
5
105
80
94
87
114
77
76
n.a.
79
68
Lead (ppm)
0.07
0.0013
0.00
Nickel
50
31
27
37
33
40
33
20
n.a.
29
24
0.10 –
0.098
n.a.
n.a.
0.098
0.098
0.09
0.098
1.58
0.098
0.098
(ppm)
Phosphate
(mg/L)
0.20
8
31