Characterization of Naphthenic Acids and Other Dissolved Organics in Natural Water from the Athabasca Oil Sands Region, Canada

Article (PDF Available)inEnvironmental Science and Technology 51(17) · July 2017with 145 Reads
DOI: 10.1021/acs.est.7b02082
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With growth of the Canadian oil sands industry, concerns have been raised about possible seepage of toxic oil sands process-affected water (OSPW) into the Athabasca River (AR). A sampling campaign in fall 2015 was undertaken to monitor for anthropogenic seepage while also considering natural sources. Naphthenic acids (NAs) and thousands of bitumen-derived organics were characterized in surface water, groundwater, and OSPW using a highly sensitive online solid phase extraction-HPLC-Orbitrap method. Elevated NA concentrations and bitumen-derived organics were detected in McLean Creek (30.1 μg/L) and Beaver Creek (190 μg/L), two tributaries that are physically impacted by tailings structures. This was suggestive of OSPW seepage, but conclusive differentiation of anthropogenic and natural sources remained difficult. High NA concentrations and bitumen-derived organics were also observed in natural water located far north of the industry, including exceedingly high concentrations in AR groundwater (A5w-GW, 2000 μg/L) and elevated concentration in a tributary river (Pierre River, 34.7 μg/L). Despite these evidence for both natural and anthropogenic seepage, no evidence of any bitumen-derived organics was detected at any location in AR mainstem surface water. The chemical significance of any bitumen-derived seepage to the AR was therefore minimal, and focused monitoring in tributaries will be valuable in the future.
Characterization of Naphthenic Acids and Other Dissolved Organics
in Natural Water from the Athabasca Oil Sands Region, Canada
Chenxing Sun,
William Shotyk,
Chad W. Cuss,
Mark W. Donner,
Jon Fennell,
Muhammad Javed,
Tommy Noernberg,
Mark Poesch,
Rick Pelletier,
Nilo Sinnatamby,
Tariq Siddique,
and Jonathan W. Martin*
Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta Canada, T6G 2G3
Department of Renewable Resources, University of Alberta, Edmonton, Alberta Canada, T6G 2H1
Integrated Sustainability Consultants Ltd., Calgary, AB Canada T2P 2Y5
SSupporting Information
ABSTRACT: With growth of the Canadian oil sands industry,
concerns have been raised about possible seepage of toxic oil
sands process-aected water (OSPW) into the Athabasca River
(AR). A sampling campaign in fall 2015 was undertaken to
monitor for anthropogenic seepage while also considering
natural sources. Naphthenic acids (NAs) and thousands of
bitumen-derived organics were characterized in surface water,
groundwater, and OSPW using a highly sensitive online solid
phase extraction-HPLC-Orbitrap method. Elevated NA
concentrations and bitumen-derived organics were detected
in McLean Creek (30.1 μg/L) and Beaver Creek (190 μg/L),
two tributaries that are physically impacted by tailings
structures. This was suggestive of OSPW seepage, but
conclusive dierentiation of anthropogenic and natural sources
remained dicult. High NA concentrations and bitumen-derived organics were also observed in natural water located far north
of the industry, including exceedingly high concentrations in AR groundwater (A5w-GW, 2000 μg/L) and elevated concentration
in a tributary river (Pierre River, 34.7 μg/L). Despite these evidence for both natural and anthropogenic seepage, no evidence of
any bitumen-derived organics was detected at any location in AR mainstem surface water. The chemical signicance of any
bitumen-derived seepage to the AR was therefore minimal, and focused monitoring in tributaries will be valuable in the future.
The Athabasca oil sands region (AOSR) of northeastern
Alberta is a vast area (142 000 km2) containing among the
largest petroleum reserves in the world. This petroleum is in
the form of bitumen, and the reserves are estimated to be
equivalent to 170 billion barrels of crude oil.
The ore may be
termed oil sands or tar sands, depending on the viscosity of the
but in this paper the term oil sands is used for
simplicity. The Athabasca River (AR) and its tributaries are
major surface features in the AOSR, with water owing north to
the Peace-Athabasca Delta, a UNESCO world heritage site.
The AR and some of its tributaries ow adjacent to major oil
sands surface mines, raising concerns about contamination of
natural water.
At oil sands surface mines, large volumes of hot water are
used to extract viscous bitumen from the raw ore, resulting in
acutely toxic oil sands process-aected water (OSPW) that is
stored in large settling basins, known as tailings ponds.
2013, tailings ponds covering 220 km2contained 975 million
m3of ne uid tailings and OSPW.
Some of the oldest tailings
ponds have now entered reclamation by dry-landscape capping
or conversion to end-pit lakes,
and OSPW in these structures
may be connected to natural waters by surface or groundwater
ow. Fresh OSPW is toxic to aquatic organisms
due to a
complex mixture of dissolved organics, including naphthenic
acids (NAs) and other water-soluble organic compounds
derived from natural bitumen.
NAs are a supercomplex
mixture of organic carboxylic acid isomers in crude oils with the
general formula of CnH2n+ZO2, where nrepresents the carbon
number, and Zspecies the degree of unsaturation or number
of rings.
NAs become concentrated in tailings ponds due to
their persistence
and continued OSPW recycling.
A recent
eects-directed analysis attributed the toxicity to a range of
compound classes, including NAs and nonacidic polar neutral
compounds containing oxygen (i.e., CxHyO2), sulfur (CxHySO),
or nitrogen (CxHyNO).
Follow up studies have recently
demonstrated that these same compound classes are lipophilic,
Received: April 21, 2017
Revised: June 21, 2017
Accepted: July 10, 2017
© XXXX American Chemical Society ADOI: 10.1021/acs.est.7b02082
Environ. Sci. Technol. XXXX, XXX, XXXXXX
and some can bioconcentrate in sh.
In 2014 we reported the
NA concentrations and ngerprints in surface water and
groundwater samples from the AOSR,
but comparably little is
known about the occurrence of these other toxic and
potentially bioaccumulative nonacidic compounds. The devel-
opment of new analytical methods and their application to
water monitoring for this broader range of bitumen-derived
organics may assist in understanding current aquatic toxico-
logical risks. Furthermore, these advancements of analytical
methods will also help with the environmental forensic
challenge of dierentiating natural bitumen-derived impacts
from anthropogenic ones.
The AR cuts into distinct geological formations as it ows
past surface mining activity, including the Cretaceous Clear-
water, McMurray, and underlying Devonian formations.
Natural outcropping of oil sands in the McMurray formation
can be seen on the banks of the river between Fort McMurray
and the Firebag River. While natural seepage of bitumen-
impacted water is known to occur, the magnitude and
signicance of this natural contamination to the AR is not
understood. Upwelling of saline groundwater into the AR has
been characterized by electromagnetic surveys and by
piezometer measurements,
but the measured presence of
salinity and major ions alone does not allow bitumen-impacted
water (i.e., from the McMurray formation which contains
bitumen) to be distinguished from saline non bitumen-
impacted groundwater originating from the underlying Devon-
Characterization of the dissolved organic compounds in
natural bitumen-impacted water has not been studied as
extensively as in OSPW, and it is not yet clear how to
distinguish natural and anthropogenic sources of bitumen-
derived organics in water samples. Advanced analytical
techniques for analysis of bitumen-impacted water have
shown promise,
in particular comprehensive two-
dimensional gas chromatography (GC×GC/MS),
mobility mass spectrometry
and methods based on ultra-
high-resolution mass spectrometry (HRMS), such as Orbitrap
and Fourier transform ion cyclotron resonance MS
For instance, Headley et al. used FTICR-
MS to prole OSPW and natural water and suggested that the
relative abundance of sulfur-containing acid species could
potentially be used for source discrimination.
Gibson et al.
combined FTICR-MS data with isotopic and geochemical
tracers for ngerprinting OSPW and seep samples, but
identication of sources still remained a challenge.
Frank et
al. suggested seepage of OSPW via groundwater into the AR
using a tiered approach including HRMS and GC×GC-MS.
Ross et al. measured NA ngerprints in the AR mainstem,
tributaries, lakes, and in natural bitumen-impacted groundwater
Although they reported similarities in
NA ngerprints between OSPW and two tributaries, conclusive
distinction of anthropogenic and natural sources could not be
It also must be noted that most analytical measurements of
dissolved organics in natural surface water and groundwater in
the AOSR have only used negative ionization mode, and thus
were limited to detection of organic acids. Only one study, by
Barrow et al.,
used both negative and positive mode together
to characterize organic compounds in OSPW, tributary rivers,
and groundwater. On the basis of this limited survey they
nevertheless suggested that sulfur-containing species (with no
oxygen), as well as hydrocarbons, both of which were only
observed in atmospheric pressure photo ionization positive
mode have potential for screening oil sands impacted samples.
In the present study, a sensitive and robust method was
developed for natural waters using in-line solid phase extraction
(SPE) coupled to HPLC-Orbitrap MS. Each water sample was
analyzed in both positive and negative mode, with atmospheric
pressure chemical ionization for proling of organic acids and
polar nonacids in a wide survey of surface water, groundwater,
and OSPW from the AOSR. The objectives were to examine
the range of NA concentrations while simultaneously proling
thousands of other organic species in an eort to maximize
information for forensics and environmental risk assessment.
Sample Collection. The focus of this work is on a total of
40 water samples collected in the fall of 2015. These included
eight groundwaters, thirty-one surface waters from the AR or its
tributaries, and one lake water. The smaller set of natural water
samples were also collected in the fall of 2014. Six OSPW from
dierent active tailings ponds were also included in this study to
contrast with natural water samples. Detailed water sampling
procedures and sample preparation are described in the
Supporting Information (SI).
Instrumental Analysis of Organic Compounds. Five
milliliters of ltered water from each sample was directly
injected to in-line SPE-HPLC/Orbitrap MS system. Detailed
analysis procedures are described in the SI.
Data Processing and Statistical Analysis. Data acquis-
ition and analysis were performed with Thermo Xcalibur 2.2
software. Under each ionization mode for each sample, mass
spectra between 7 and 24 min of the total ion chromatograms
were averaged to generate lists of m/zwith corresponding
intensities. These lists were rened by blank subtraction using
eld blank data, and only peaks with signal/noise ratio 10
were used for further data analysis. Empirical formula
assignments were based on the following elemental restrictions:
010. All species were binned into
major heteroatomic classes under negative ionization mode, for
example Ox
, NSOx
, and
also under positive ionization mode, for example Ox+,NO
x+, NSOx+. The relative contribution of each
heteroatomic class in each sample was calculated as the sum
intensity of all species in the class divided by total intensity of
all species in the sample under negative and positive ionization,
respectively. Principal component analysis (PCA) was rst
conducted on the organic prole under negative ionization
using relative contributions of the heteroatomic classes that
were further transformed using log10(x+ 0.78) (log10 b+ log10
(Xmaximum +b) = 0 to get bvalue). A separate PCA was
conducted using relative contributions of the heteroatomic
classes in positive ionization that were transformed using
log10(x+ 0.86). PCA was performed using XLSTAT (V2016.4,
Addinsoft, Paris, France).
NA Concentrations and Fingerprints. Identication of
NA (CnH2n+ZO2) species was based on accurate mass
measurement to within 3 ppm of the theoretical masses for
NAs with n=924 and Z=0to20. In this study, Z=0
species and two major Z=2 species (n= 16 and 18) were
eliminated from all data sets, because these species are
dominated by biological fatty-acids that are detectable at high
concentrations in all samples, including those upstream of oil
sands activity.
The relative contribution of each NA species in
each sample was calculated as the intensity of each NA species
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divided by total intensity of all NA species in the sample. These
relative contributions were transformed using log10(x+ 0.95),
then used for PCA to examine variability of NA ngerprints
between samples. Total NA concentrations were calculated
using a calibration curve of Rened Merichem NAs, and the
LOD was determined as 2 μg/L. Please see SI for details.
Geochemical Analysis. Major anions (Cl,SO
42, and
CO32) were quantied by ion chromatography and major
cations (Na+,K
2+) were determined by inductively
coupled plasma optical emission spectroscopy. Detailed
procedures are described in Shotyk et al.
concentrations in groundwaters were measured by liquid
scintillation counting, and expressed as tritium units (TU)
where 1 TU was dened as the presence of one tritium in 1018
atoms of hydrogen. The analysis was performed by Environ-
mental Isotope Laboratory at University of Waterloo.
Water Geochemistry. Water samples were initially
categorized by Piper plot, a method which considers only the
relative major inorganic ion balance (Figure S1). Most natural
surface water samples were of freshwater type, with the
exception of Saline Lake which receives high salinity spring
water. As in previous reports,
natural AOSR groundwaters
had a wide range of ionic character, ranging from those typical
of fresh surface water (e.g., A17w-GW), to more saline samples
(e.g., A5w-GW, Saline Spring, FMSS and NSS) similar to
OSPW. Other natural groundwaters had mixed saline-fresh
character (e.g., A15w-GW, A16w-GW, and A18w-GW).
Although A16w-GW, A17w-GW, and A18w-GW were sampled
in the vicinity of tailings ponds, the major ions showed little
similarity to OSPW, which normally has high salinity and
moderate alkalinity. Interestingly, groundwater sampled at
locations far away from known industrial activity (e.g., A5w-
GW, NSS, FMSS, and Saline Spring) all grouped relatively
close to OSPW in the Piper plot (Figure S1).
Tritium measurements in groundwater were as follows: A18-
GW (6.1 TU), A17-GW (11.8 TU), A16-GW (6.5 TU), A15-
GW (7.1 TU), Saline Spring (1.4 TU), A5w-GW (0.9 TU),
NSS (<0.8 TU), and FMSS (<0.8 TU). Unlike groundwater
with higher relative tritium such as A18, A17, A16, and A15-
GW, tritium activities in A5w-GW, NSS, and FMSS were lower,
indicating little to no inuence of modern discharge.
NA Concentrations. Total NA concentrations in surface
water and groundwater samples from 2014 and 2015 were
similar between years (Table S1) and were also highly
correlated (r> 0.9). Thus, we focused on the more
comprehensive data set from 2015, and total NA concen-
trations in 2015 are shown spatially in Figure 1.NA
concentrations in the AR mainstem ranged from 11.8 to 20.9
μg/L (average 16.3 μg/L) but one way ANOVA showed no
signicant dierence in NA concentrations at upstream AR sites
(from UA04 to A19e) compared to those sites in the vicinity of
industrial activity (from A18w to A10w), or compared to
downstream AR sites (from A9w to A1e). Moreover, NA
concentrations in three AR water samples collected closest to
surface mining activity (i.e., A16w, A17w, and A18w) had an
average concentration of 14.7 μg/L, below the average among
all AR mainstem samples. Thus, in the AR mainstem there was
no evidence of any natural or anthropogenic bitumen-derived
impact based on NA concentrations.
For tributaries to the AR, elevated NA concentrations were
observed in McLean Creek (30.1 μg/L) and in Beaver Creek
(190 μg/L). These two creeks ow across industrial sites, but
can be compared to the NA concentration in the unimpacted
Pierre River (34.7 μg/L). Pierre River is located far away from
known industrial sources (Figure 1) but drains an area of black
In the recent study by Arens et al.,
elevated NA
Figure 1. Map of study area showing surface water and groundwater sampling locations. The size of the circle at each location is proportional to the
measured naphthenic acid (NA) concentration. Locations of tailings ponds containing OSPW are shown as Wet Tailings.
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concentrations were observed in the Steepbank, MacKay and
Muskeg rivers, compared to Ells and Clearwater rivers, which
was also true in the current study. However, McLean Creek,
Beaver Creek, and Pierre River, which contain even higher NA
concentrations, were not sampled in study of Arens et al.
Groundwaters generally had higher NA concentrations than
all surface waters, ranging up to 2.00 mg/L at A5w-GW. This
exceedingly high concentration is only 315×lower than NA
concentrations in OSPW from active tailings ponds (6.34 to
29.0 mg/L) (Table S1). The NA concentrations in OSPW were
generally consistent with Han at al.s study.
The NA
concentration reported here for A5w-GW (2015) is similar to
that obtained during the 2014 fall (2.20 mg/L) (Table S1). The
low tritium concentration in A5w-GW also conrmed that
natural inputs are the most likely source of these NAs.
Relatively high NA concentrations were also detected in NSS,
FMSS, and Saline Spring (231 to 765 μg/L), which are also far
from known oil sands industrial activities.
Among groundwater sampled in the vicinity of oil sands
industrial sites, a relatively high NA concentration (92.2 μg/L)
was observed at A18w-GW. The sampling location of A18w-
GW is close to the location of near-eld drive point 4 and 5in
Frank et al.s study
where it was suggested that OSPW was
reaching the AR.
NA Fingerprints. The distribution of various NAs (varying
by carbon number and Z) in a water sample may be used as
ngerprints to help dierentiate distinct sources. In context of
the current study, the challenge was to distinguish 3 broad
sources: nonbitumen derived natural organic acids (e.g., fatty
acids) of biological origin, natural bitumen-derived NAs, and
anthropogenic bitumen-derived NAs. The NA ngerprints of
nonbitumen impacted water samples, such as those collected
upstream (UA04-River), are contrasted with various bitumen-
impacted waters (OSPW4, A5w-GW, and McLean Creek) in
Figure 2. As previously discussed, NA ngerprints of bitumen-
impacted water samples have a distinct Gaussian-distribution of
NA species (CnH2n+ZO2) that generally peak around n= 14 and
Furthermore, with the current method we are able to
see a secondary Gaussian-distribution of NA species in the
bitumen-impacted waters, peaking at approximately n= 18 and
Z=12, which is absent in nonbitumen impacted water.
Similar bitumen-impacted NA ngerprints were also observable
in NSS, FMSS, Saline Spring, and Pierre River (Figure S2b)
samples; all of which are far from locations that would be
reasonably expected to be impacted by OSPW seepage. This
strongly suggests natural contributions of bitumen-derived NAs
to these particular surface waters and groundwaters.
Greater ambiguity in assigning source comes from examining
the NA ngerprints in water from sites that are close to
anthropogenic activity. For example, McLean Creek (Figure 2),
whose upper watershed is partially impounded by tailings
ponds (i.e., collection site of OSPW4) and oil-sands mining,
or Beaver Creek (Figure S2a), which has been known to receive
seepage and runofrom a nearby tailings pond
collection site of OSPW2). Similarly, for A18w-GW (Figure
S2c), which is groundwater sampled in the AR mainstem
adjacent to a tailings pond. These three samples all showed
bitumen-impacted NA ngerprints, which were similar to both
the NA ngerprints of a pure anthropogenic NA source (e.g.,
OSPW4) and of a pure natural NA source (e.g., A5w-GW).
Moreover, as discussed above, McLean Creek and Beaver River
also had elevated NA concentrations.
PCA was performed using transformed relative contribution
of each NA species in all water samples, as described in NA
Concentrations and Fingerprints(Figure S3). A5w-GW
plotted close to OSPW, indicating a similar NA composition
to OSPW despite the fact that A5w-GW is remote and assumed
to be exclusively natural. Among tributaries, Pierre River,
Beaver Creek, and McLean Creek plotted separately from the
rest of the tributaries. Given the high similarity of bitumen-
impacted NA ngerprints in OSPW and natural water, it is
Figure 2. NA species ngerprints in bitumen-impacted waters, including (a) oil sands process aected water (OSPW4), (b) a natural groundwater
(A5w-GW), (c) an impacted tributary (McLean Creek), and (d) a nonbitumen-impacted water collected upstream of oil sands industry in the
Athabasca River (UA04-River).
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dicult to assign source based on NA ngerprints as we
reported earlier in Ross et al.
Organics Proling in Negative Ionization Mode.
Among all samples, an average of 750 organic acid species
could be detected and assigned a formula in negative ionization
mode. Resulting proles (Figure 3a) are shown for a
representative tailings pond (OSPW4), natural bitumen-
impacted groundwater (A5w-GW), surface water from an
impacted tributary (McLean Creek), and for AR surface water
collected in the vicinity of a tailings pond (A18w-River). The
(i.e., NAs), O3
, and O4
heteroatomic classes dominated
the organic acids in all water samples in this study, similar to
previous proles reported using similar analytical condi-
In the OSPW and natural bitumen-impacted groundwater
(Figure 3a) the O2
class was dominant followed by O4
, with other oxygenated classes in lower relative abundance.
Frank et al. proposed that higher O2
ratios (range 1.2 to
1.7 in their analysis) could be used as an indicator of OSPW
impacted water.
However, here high O2
ratios were not
only observed in OSPW (1.2 to 1.8) but also in far-eld natural
groundwater such as A5w-GW (1.3). Yi et al.
also reported
a wide range of O2
ratios that overlapped among sample
types, limiting the utility of this proposed tool and emphasizing
the diculty in dierentiating natural and anthropogenic
Natural, and likely nonbitumen impacted AR water (Figure
3a, A18w-River) had a dierent prole whereby the O3
was most abundant with a Gaussian distribution of Ox
around it. Very similar proles were also observed upstream
(UA04-River) and downstream (A5w-River) of oil sands
industrial sites (Figure S4a), and there was no signicant
change in absolute abundance of these oxygenated components
(or of any heteroatomic class) in AR surface water moving
through the oil sands industrial zone. In the mainstem samples,
these oxygen-containing species are not bitumen-derived acids
but are natural dissolved organic matter of contemporary
biological origin, perhaps fulvic acids.
Nitrogen-containing classes (NOx
and N2Ox
) were not
elevated in bitumen-impacted waters, and showed no signicant
change in absolute abundance in AR surface water moving
through the oil sands industrial zone. Thus, these are likely also
natural components of dissolved organic matter.
Figure 3. Heteroatomic class proles of all detected organics in OSPW4, A5w-GW, McLean Creek, and A18w-River analyzed in (a) negative
ionization mode (blue) and (b) positive ionization mode (red).
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Sulfur-containing classes (SOx
, and S(12)
) were
detected in all the water sample types, but no signicant
changes in their absolute abundance were detected in the AR
mainstem moving through the oil sands industrial zone.
Nevertheless, the SO2
class was enhanced in bitumen-
impacted waters (e.g., Figure 3a, OSPW4, A5w-GW, McLean
Creek), relative to non-bitumen-impacted AR surface water
(e.g., Figure 3a, A18w-River).
Organics Proling in Positive Ionization Mode. Most
previous research on the mass spectral characterization of
organics in OSPW and bitumen-impacted natural water were
conducted only in negative mode ionization
which is
suitable for organic acids. However, an even greater number of
chemical species, including organic bases and neutral polar
compounds can be detected in bitumen-impacted water by
positive ionization.
Among all samples in this work, on
average 950 polar organic species were detected and assigned
formulas in positive ionization mode; greater than in negative
ionization mode.
Pereira et al. showed that OSPW O2
species (NAs) were
distinct from O2+species with the same empirical formula.
natural groundwater, here we can conrm the same as was
shown for OSPW. For example, the negative ion organic acid
species [C15H24O2H]detected at m/z235.1695, and the
corresponding nonacid positive ion [C15H24O2+H]
at m/z237.1852 eluted at dierent retention times (Figure
S5a), proving that they are composed of dierent molecules.
For the rst time we can further conrm that this phenomenon
is not limited only to the O2classes, but also to most species in
the SO classes. This is of importance because SO+compounds
are part of the toxic OSPW fraction.
For example, C17H28OS
detected in negative mode as the organic acid species
[C17H28OS H]at m/z279.1788 had a distinct retention
time from the corresponding nonacid species detected in
positive ion mode as [C17H28OS + H]+at m/z281.1934
Figure 4. PCA of heteroatomic proles in various Athabasca River waters (ARW), tributary waters (TW), groundwaters (GW), lake water (Lake),
and OSPW samples. Loadings plot (a) and scores plot (c) in negative ionization mode, and loadings plot (b) and scores plot (d) in positive
ionization mode are shown.
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(Figure S5b). For this reason, there is an advantage to using
both positive and negative ion modes together for monitoring
of natural water in the AOSR; the two data sets are not
redundant and the positive ionization mode can reveal the
presence of toxic compound classes.
Heteroatomic class distributions in positive ionization mode
(Figure 3b) showed that in bitumen-impacted waters (e.g.,
OSPW4, A5w-GW) that the relative abundance of major sulfur-
containing classes (SOx+) was of similar magnitude to the most
abundant oxygen containing classes (Ox+), a much dierent
pattern from in negative ionization mode. Moreover, in the
bitumen-impacted samples OSPW4 and A5w-GW, the major
Ox+classes were O2+>O
3+, which was similar to the SOx+
classes, whereby SO2+>SO
3+. The enrichment of sulfur-
containing classes was also observed in the bitumen-impacted
tributaries, such as Beaver Creek and McLean Creek, but not in
AR surface water. As in negative ionization mode, the
heteroatomic proles of the AR mainstem were very similar
upstream, downstream (Figure S4b) and in the vicinity of oil
sands industry (A18w-River, Figure 3b). No trend or signicant
changes in the absolute abundance of these heteroatom classes
were observed in the AR mainstem moving through the oil
sands industrial zone.
PCA of Organic Prole under Negative and Positive
Ionization. PCA analysis was rst conducted on the
heteroatomic proles detected under negative ionization
(Figure 4a). The AR mainstem samples grouped separately
with positive loading on PC1, driven to a great extent by the
high relative abundance of the multioxygenated classes O(38)
as well as N2Ox
and NOx
(Figure 4c); as discussed, these are
likely components of natural dissolved organic carbon of
contemporary biological origin. In contrast, OSPW and natural
bitumen-impacted groundwater (A5w-GW and NSS) plotted
with strong negative loading on PC1 (Figure 4a), driven by the
high relative abundance of NAs (O2
) and many sulfur
containing acids (SO(24)
)(Figure 4c). Groundwater samples
spread out the most on both PC1 and PC2 axes (Figure 4a),
reecting the high variability in the organics composition for
this sample type. A17w-GW and A16w-GW clustered close to
tributary water samples. A18w-GW also plotted closer to the
tributary samples than to OSPW, even though it had a bitumen-
impacted NA ngerprint. FMSS, A15-GW and Saline Spring
plotted between natural surface water and OSPW, while A5w-
GW and NSS were well separated on PC1 from AR water and
from most of the tributary waters. Similar PCA results were
presented by Gibson et al.,
in which one groundwater plotted
very close to Shell Albian OSPW, despite that this groundwater
was collected 50 km upstream from the tailings pond. Most
tributary rivers overlapped with AR surface water, but were
more variable, generally spreading out more on the PC2 axis
(Figure 4a). McLean Creek and Beaver Creek were the
exceptions, and the only tributary samples with negative
loadings on PC1, plotting closer to OSPW and natural
bitumen-impacted water.
A separate PCA analysis was conducted on the heteroatomic
proles detected in positive ionization (Figure 4b). Similar to
negative mode (Figure 4a), all AR mainstem samples still
grouped together and were well separated from OSPW and
natural bitumen-impacted groundwater (A5w-GW and NSS).
This separation was mainly driven by the high relative
abundance of the multioxygenated classes O(38)+and NSO+
in AR mainstem, as well as sulfur containing compounds
(SO(14)+,S(12)+) in bitumen-impacted samples (Figure 4d).
Groundwater samples also still spread out the most on both
PC1 and PC2 axes (Figure 4b). Unlike PCA in negative
ionization mode (Figure 4a), A18w-GW plotted close to
OSPW and natural bitumen-impacted samples A5w-GW, NSS
and FMSS (Figure 4b). Similar to negative mode PCA results
(Figure 4a) most of the tributary samples plotted away from
OSPW. McLean Creek and Beaver Creek were the only
tributary samples plotting closer to OSPW and natural
bitumen-impacted water. Saline Spring, which is a natural
bitumen-impacted groundwater, ows into Saline Lake, but the
organic proles of Saline Lake under both negative and positive
ionization were more similar to the AR mainstem and tributary
water samples (Figure 4a,b), indicating other dominant sources
of dissolved organics in Saline Lake. PCA is a good descriptive
tool for summarizing and categorizing these water samples
based on the relative contribution of the heteroatom classes.
However, there was still overlap between natural bitumen-
impacted groundwater and OSPW, which made source
attribution challenging.
SO+Proles. On the basis of the above PCA analysis, SO+
was one of the most important variables (on F1 in Figure 4d)
for distinguishing bitumen-impacted samples. Moreover, SO+
species were never detected in the AR mainstem, nor in most
tributary samples except for the impacted tributaries, McLean
Creek and Beaver Creek. SO+species proles are shown for
OSPW4, the impacted tributary McLean Creek, and for natural
bitumen-impacted groundwater A5w-GW (Figure S6). For the
OSPW4, SO+species with Z from 0 to 20 were detected, with
some of the most abundant species having Z=6 and 8. For
natural bitumen-impacted groundwater A5w-GW, the prole
had the same most abundant species as in OSPW4, but the
range of Z was limited to between 4 and 14. Very similar
SO+proles were observed in natural groundwater NSS and
FMSS. In McLean Creek, the most abundant SO+species had
Z=2 and 4, although Z ranged from 0 to 20, more similar
to OSPW4 but with dierent relative proportions. Given that
SO+species with a Z=0,2, 16, 18, and 20 were not
detected in A5w-GW, the source of these SO+species in
McLean Creek may have been OSPW4; which was sampled
from the tailings pond located adjacent to this creek. However,
we cannot rule out the possibility that this creek may also
receive natural input of bitumen organics. Similar observation
was also seen on the SO+prole of the other impacted tributary
Beaver Creek, the SO+prole of which is very similar to
OSPW2 especially in the Zof 14 serial (Figure S6).
Eects-directed analysis has shown that the SO+class was
among the most acutely toxic chemicals in OSPW,
and overall
this class was also among the most hydrophobic and possibly
It is suggested that future water monitoring
in the AOSR include the SO+class, and further investigations
should also be undertaken to identify the structure, environ-
mental fate and toxic mechanisms of these unknown
Environmental Signicance. The very high concentration
of NAs in natural groundwater sampled far from any known
mining activity was unexpected. A5w-GW had the highest NA
concentrations of all environmental samples and approached
the concentrations found in OSPW from active tailings ponds.
Moreover, the NA ngerprint and the overall organic prole of
A5w-GW resembled OSPW very closely. Therefore, natural
contribution of bitumen-derived NAs and other organics must
be taken into consideration in studies of the lower reaches of
Environmental Science & Technology Article
DOI: 10.1021/acs.est.7b02082
Environ. Sci. Technol. XXXX, XXX, XXXXXX
the AR watershed, not only for forensic purposes but also for
the potential of natural sources to cause biological eects.
Having said the above, the conclusion that comes from
simultaneous monitoring of AR surface water adjacent to
bitumen-impacted groundwater or tributaries was that in no
location could we detect the characteristic signal of bitumen-
derived organics in the AR mainstem. This was true even with
the highly sensitive analytical method used here, and even in
the surface water zone (i.e., A5w-ARW) where A5w-GW was
shown to have exceptionally high concentrations of acutely
toxic NAs and SO+compounds. This suggests that the ux of
this naturally impacted groundwater into the river was low,
relative to the high ow rate of the river, even during this
sampling campaign in the fall when surface water ow rates are
the lowest. It has been reported that average (over 76 months)
saline groundwater ow into AR is between 0.05% and 0.19%
of total river discharge.
Even if the extreme case is assumed
here that all the 0.19% of river discharge is from A5w-GW (NA
2000 μg/L), then the NA concentration in the river after
mixing would be approximately 3 μg/L, which is only slightly
above the LOD of our method (2 μg/L). Thus, the chemical
signicance of any bitumen-derived seepage to the AR is of low
general concern today, irrespective of whether the sources are
anthropogenic or natural. Future monitoring and environ-
mental forensic work could focus on seepage into tributaries,
with less emphasis on the AR mainstem where dilution is so
Owing to elevated NA concentrations and compositional
proles similar to OSPW, Beaver Creek and McLean Creek
continue to be areas of concern. Although their chemical
impact on the AR was not measurable in this sampling
campaign, best eorts at controlling any seepage here should be
considered by companies and relevant authorities.
SSupporting Information
. The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.est.7b02082.
Chemicals and materials, water sampling procedures,
quality control and sample preparation, in-line SPE-
HPLC/Orbitrap analysis, NA concentrations, Table S1,
Figures S1S6 (PDF)
Corresponding Author
*Phone: (780) 492-1190; e-mail:
Chenxing Sun: 0000-0001-9331-4591
William Shotyk: 0000-0002-2584-8388
Chad W. Cuss: 0000-0002-4351-8702
Tariq Siddique: 0000-0003-2371-0200
Jonathan W. Martin: 0000-0001-6265-4294
The authors declare no competing nancial interest.
The authors gratefully acknowledge Alberta Innovates (AI) and
Canadas Oil Sands Innovation Alliance (COSIA) funding for
this project; Thank you to Brett Purdy (AI) and John Brogly
(COSIA) for managerial support of this project and Warren
Zubot from Syncrude for providing oil sands water samples;
Tracy Gartner for nancial administration.
(1) Canadas Oil Sands-Opportunities and Challenges to 2015: An
Update; National Energy Board: Calgary, AB, Canada, 2006.
(2) Shotyk, W.; Appleby, P. G.; Bicalho, B.; Davies, L.; Froese, D.;
Grant-Weaver, I.; Krachler, M.; Magnan, G.; Mullan-Boudreau, G.;
Noernberg, T.; Pelletier, R.; Shannon, B.; van Bellen, S.; Zaccone, C.
Peat bogs in northern Alberta, Canada reveal decades of declining
atmospheric Pb contamination. Geophys. Res. Lett. 2016,43 (18),
(3) Environmental Canada. Daily discharge data for Athabasca River.
07DA001&mode=Table (Accessed January 19, 2017).
(4) Kindzierski, W.; Jin, J.; Gamal El-Din, M. Review of Health Eects
of Naphthenic Acids: Data Gaps and Implications for Understanding; Oil
Sands Research and Information Network, University of Alberta,
School of Energy and the Environment: Edmonton, Alberta, 2012, No.
TR-20, 43.
(5) Royal Society of Canada. Environmental and Health Impacts of
CanadaS Oil Sands Industry; Royal Society of Canada Expert Panel:
Ottawa, ON, Canada. 2010.
(6) Schramm, L. L.; Stasiuk, E. N.; MacKinnon, M., Eds. Surfactants,
Fundamentals and Applications in the Petroleum Industry; Cambridge
University Press: Cambridge, UK, 2000.
(7) Albertas Energy Reserves 2008 and Supply/Demand Outlook
20092018, ST982009; Energy Resources Conservation Board:
Calgary, AB, Canada, 2009.
(8) Government of Alberta. Environment and Sustainable Resource
Development. Tailings ponds, oil sands tailings ponds locations. (Accessed September 20, 2016).
(9) Suncor. Pond 1 reclamation.
2010/en/responsible/3508.aspx (Accessed on October 14, 2016).
(10) Syncrude. Water capping.
capping/ (Accessed October 11, 2016).
(11) MacKinnon, M. D.; Boerger, H. Description of two treatment
methods for detoxifying oil sands tailings pond water. Water Qual. Res..
J. Canada 1986,21, 496512.
(12) Allen, E. W. Process water treatment in Canadas oil sands
industry: I. Target pollutants and treatment objectives. J. Environ. Eng.
Sci. 2008,7, 123138.
(13) Frank, R. A.; Kavanagh, R.; Kent Burnison, B.; Arsenault, G.;
Headley, J. V.; Peru, K. M.; Van Der Kraak, G.; Solomon, K. R.
Toxicity assessment of collected fractions from an extracted
naphthenic acid mixture. Chemosphere 2008,72 (9), 13091314.
(14) Han, X.; MacKinnon, M. D.; Martin, J. W. Estimating the in situ
biodegradation of naphthenic acids in oil sands process waters by
HPLC/HRMS. Chemosphere 2009,76,6370.
(15) Brown, L. D.; Ulrich, A. C. Oil sands naphthenic acids: A review
of properties, measurement and treatment. Chemosphere 2015,127,
(16) Morandi, G. D.; Wiseman, S. B.; Pereira, A.; Mankidy, R.; Gault,
I. G. M.; Martin, J. W.; Giesy, J. P. Effects-directed analysis of dissolved
organic compounds in oil sands process-affected water. Environ. Sci.
Technol. 2015,49, 1239512404.
(17) Zhang, K.; Wiseman, S. B.; Giesy, J. P.; Martin, J. W.
Bioconcentration of dissolved organic compounds from oil sands
process-affected water by Medaka (Oryzias latipes): Importance of
partitioning to phospholipids. Environ. Sci. Technol. 2016,50, 6574
(18) Ross, M. S.; Pereira, A.d.S.; Fennell, J.; Davies, M.; Johnson, J.;
Sliva, L.; Martin, J. W. Quantitative and qualitative analysis of
naphthenic acids in natural waters surrounding the Canadian oil sands
industry. Environ. Sci. Technol. 2012,46, 1279612805.
(19) Gibson, J. J.; Fennell, J.; Birks, S. J.; Yi, Y.; Moncur, M. C.;
Hansen, B.; Jasechko, S. Evidence of discharging saline formation
Environmental Science & Technology Article
DOI: 10.1021/acs.est.7b02082
Environ. Sci. Technol. XXXX, XXX, XXXXXX
water to the Athabasca River in the oil sands mining region, northern
Alberta. Can. J. Earth Sci. 2013,50, 12441257.
(20) Barrow, M. P.; Peru, K. M.; Fahlman, B.; Hewitt, L. M.; Frank,
R. A.; Headley, J. V. Beyond naphthenic acids: Environmental
fingerprinting of water from natural sources and the Athabasca oil
sands industry using atmospheric pressure photoionization Fourier
transform ion cyclotron mass spectrometry. J. Am. Soc. Mass Spectrom.
2015,26, 15081521.
(21) Barrow, M. P.; Witt, M.; Headley, J. V.; Peru, K. M. Athabasca
oil sands process water: Characterization by atmospheric pressure
photoionization and electrospray ionization Fourier transform ion
cyclotron resonance mass spectrometry. Anal. Chem. 2010,82, 3727
(22) Frank, R. A.; Roy, J. W.; Bickerton, G.; Rowland, S. J.; Headley,
J. V.; Scarlett, A. G.; West, C. E.; Peru, K. M.; Parrott, J. L.; Conly, F.
M.; Hewitt, L. M. Profiling oil sands mixtures from industrial
developments and natural groundwaters for source identification.
Environ. Sci. Technol. 2014,48, 26602670.
(23) Headley, J.; Peru, K. M.; Barrow, M. P.; Derrick, P. J.
Characterization of naphthenic acids from Athabasca oil sands using
electrospray ionization: The significant influence of solvents. Anal.
Chem. 2007,79, 62226229.
(24) Headley, J. V.; Peru, K. M.; Fahlman, B.; Colodey, A.;
McMartin, D. W. Selective solvent extraction and characterization of
the acid extractable fraction of Athabasca oil sands process waters by
Orbitrap mass spectrometry. Int. J. Mass Spectrom. 2013,345, 104
(25) Headley, J. V.; Peru, K. M.; Janfada, A.; Fahlman, B.; Gu, C.;
Hassan, S. Characterization of oil sands acids in aquatic plant tissue
using Orbitrap ultra-high resolution mass spectrometry with electro-
spray ionization. Rapid Commun. Mass Spectrom. 2011,25, 459462.
(26) Nyakas, A.; Han, J.; Peru, K. M.; Headley, J. V.; Borchers, C. H.
Comprehensive analysis of oil sands processed water by direct-infusion
Fourier-transform ion cyclotron resonance mass spectrometry with
and without offline UHPLC sample refractionation. Environ. Sci.
Technol. 2013,47, 44714479.
(27) Pereira, A. S.; Martin, J. W. On-Line Solid Phase Extraction-
HPLC-Orbitrap Mass Spectrometry for Screening and Quantifying
Targeted and Non-Targeted Analytes in Oil Sands Process-Aected
Water and Natural Waters in the Athabasca Oil Sands Region; Oil Sands
Research and Information Network, University of Alberta, School of
Energy and Environment: Edmonton, Alberta, Canada. 2014, No. TR-
45, 33.
(28) Pereira, A. S.; Martin, J. W. Exploring the complexity of oil sands
process-affected water by high efficiency supercritical fluid chromatog-
raphy/Orbitrap mass spectrometry. Rapid Commun. Mass Spectrom.
2015,29, 735744.
(29) Pereira, A. S.; Bhattacharjee, S.; Martin, J. W. Characterization of
oil sands process-affected waters by liquid chromatography orbitrap
mass spectrometry. Environ. Sci. Technol. 2013,47, 55045513.
(30) Rowland, S. J.; West, C. E.; Scarlett, A. G.; Jones, D.; Frank, R.
A. Identification of individual tetra- and pentacyclic naphthenic acids
in oil sands process water by comprehensive two-dimensional gas
chromatography/mass spectrometry. Rapid Commun. Mass Spectrom.
2011,25, 11981204.
(31) Rowland, S. J.; West, C. E.; Jones, D.; Scarlett, A. G.; Frank, R.
A.; Hewitt, L. M. Steroidal aromatic naphthenic acids in oil sands
process affected water: Structural comparisons with environmental
estrogens. Environ. Sci. Technol. 2011,45, 98069815.
(32) Gabryelski, W.; Froese, K. L. Characterization of Naphthenic
Acids by Electrospray Ionization High-Field Asymmetric Waveform
Ion Mobility Spectrometry Mass Spectrometry. Anal. Chem. 2003,75
(17), 46124623.
(33) Headley, J. V.; Barrow, M. P.; Peru, K. M.; Fahlman, B.; Frank,
R. A.; Bickerton, G.; McMaster, M. E.; Parrott, J.; Hewitt, L. M.
Preliminary fingerprinting of Athabasca oil sands polar organics in
environmental samples using electrospray ionization Fourier transform
ion cyclotron resonance mass spectrometry. Rapid Commun. Mass
Spectrom. 2011,25, 18991909.
(34) Gibson, J. J.; Birks, S.; Moncur, M.; Yi, Y.; Tattrie, K.; Jasechko,
S.; Richardson, K.; Eby, P. Isotopic and Geochemical Tracers for
Fingerprinting Process-Aected Waters in the Oils Sands Industry: A Pilot
Study. Oil Sands Research and Information Network, University of
Alberta, School of Energy and Environment, Edmonton, Alberta,
Canada, 2011, Report No. TR-12, 109.
(35) Shotyk, W.; Bicalho, B.; Cuss, C. W.; Donner, M. W.; Grant-
Weaver, I.; Haas-Neill, S.; Javed, M. B.; Krachler, M.; Noernberg, T.;
Pelletier, R.; Zaccone, C. Trace metals in the dissolved fraction (< 0.45
μm) of the lower Athabasca River: Analytical challenges and
environmental implications. Sci. Total Environ. 2017,580, 660669.
(36) Dufresne, M. B.; Eccles, D. R.; Leckie, D. A. The Geological and
Geochemical Setting of the Mid-Cretaceous Shaftesbury Formation and
Other Colorado Group Sedimentary Units in Northern Alberta. Alberta
Energy and Utilities Board and Alberta Geological Survey 2001,
Special Report 09.
(37) Arens, C. J.; Arens, J. C.; Hogan, N. S.; Kavanagh, R. J.; Berrue,
F.; Van Der Kraak, G. J.; van den Heuvel, M. R. Population impacts in
white sucker (Catostomus commersonii) exposed to oil sandsderived
contaminants in the Athabasca River. Environ. Toxicol. Chem. 2017,1
(38) Han, J.; Yi, Y.; Lin, K.; Birks, J.; Gibson, J.; Borchers, C. H.
Molecular profiling of naphthenic acids in technical mixtures and oil
sands process water using a polar reversed-phase liquid chromatog-
raphy-mass spectrometry. Electrophoresis 2016,37 (2324), 3089
(39) RAMP. Regional Aquatics Monitoring Program. 2011 Technical
Report. 2012.
(40) Golder Associates. Beaver Creek Proling Program 2008 Field
Study. Calgary, AB, 2009.
(41) Yi, Y.; Birks, S. J.; Cho, S.; Gibson, J. J. Characterization of
organic composition in snow and surface waters in the Athabasca Oil
Sands Region, using ultrahigh resolution Fourier transform mass
spectrometry. Sci. Total Environ. 2015,518519, 148158.
(42) Yi, Y.; Gibson, J. J.; Birks, J.; Han, J.; Borchers, C. H. Comment
on Profiling oil sands mixtures from industrial developments and
natural groundwaters for source identification. Environ. Sci. Technol.
2014,48, 1101311014.
(43) Wagner, S.; Riedel, T.; Niggemann, J.; Vähätalo, A. V.; Dittmar,
T.; Jaffé
, R. Linking the molecular signature of heteroatomic dissolved
organic matter to watershed characteristics in world rivers. Environ. Sci.
Technol. 2015,49, 1379813806.
(44) Zhang, K.; Pereira, A. S.; Martin, J. W. Estimates of octanol
water partitioning for thousands of dissolved organic species in oil
sands process-affected water. Environ. Sci. Technol. 2015,49, 8907
Environmental Science & Technology Article
DOI: 10.1021/acs.est.7b02082
Environ. Sci. Technol. XXXX, XXX, XXXXXX
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    The complex mixture of dissolved organics in oil sands process-affected water (OSPW) is acutely lethal to fish at environmentally relevant concentrations, but few bioconcentration factors (BCFs) have been measured for its many chemical species. Japanese medaka (Oryzias latipes) were exposed to 10% OSPW, and measured BCFs were evaluated against predicted BCFs from octanol-water distribution ratios (DOW) and phospholipid membrane-water distribution ratios (DMW). Two heteroatomic chemical classes detected in positive ion mode (SO+, NO+) and one in negative mode (O2-; also known as naphthenic acids) had the greatest DMW values, as high as 10,000. Estimates of DMW were similar to and correlated with Dow for O+, O2+, SO+ and NO+ chemical species, but for O2- and SO2- species the DMW values were much greater than the corresponding Dow, suggesting the importance of electrostatic interactions for these ionizable organic acids. Only SO+, NO+ and O2- species were detectable in medaka exposed to OSPW, and BCFs for SO+ and NO+ species ranged from 0.6 to 28 L/kg, lower than predicted (i.e. 1.4 to 1.7×103 L/kg), possibly due to biotransformation of these hydrophobic substances. BCFs of O2- species ranged from 0.7 to 53 L/kg, similar to predicted values and indicating that phospholipid partitioning was an important bioconcentration mechanism.
  • Article
    Acute toxicity of oil sands process-affected water (OSPW) is caused by its complex mixture of bitumen-derived organics, but the specific chemical classes that are most toxic have not been demonstrated. Here, effects-directed analysis was used to determine the most acutely toxic chemical classes in OSPW collected from the world's first oil sands end-pit lake. Three sequential rounds of fractionation, chemical analysis (ultra-high resolution mass spectrometry), and acute toxicity testing (96 hr fathead minnow embryo lethality, and 15 min Microtox® bioassay) were conducted. Following primary fractionation, toxicity was primarily attributable to the neutral extractable fraction (F1-NE), containing 27% of original organics mass. In secondary fractionation, F1-NE was sub-fractionated by alkaline water washing, and toxicity was primarily isolated to the ionizable fraction (F2-NE2) containing 18.5% of the original organics mass. In the final round, chromatographic sub-fractionation of F2-NE2 resulted in two toxic fractions, with the most potent (F3-NE2a, 11% of original organic mass) containing predominantly naphthenic acids (O2-). The lesser toxic fraction (F3-NE2b, 8% of original organic mass) contained predominantly non-acid species (O+, O2+, SO+, NO+). Evidence supports naphthenic acids as among the most acutely toxic chemical classes in OSPW, but non-acidic species also contribute to acute toxicity of OSPW.
  • Article
    Large world rivers are significant sources of dissolved organic matter (DOM) to the oceans. Watershed geomorphology and land use can drive the quality and reactivity of DOM. Determining the molecular composition of riverine DOM is essential for understanding its source, mobility and fate across landscapes. In this study, DOM from the main stem of ten global rivers covering a wide climatic range and land use features was molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). FT-ICR mass spectral data revealed an overall similarity in molecular components among the rivers. However, when focusing specifically on the contribution of non-oxygen heteroatomic molecular formulae (CHON, CHOS, CHOP, etc.) to the bulk molecular signature, patterns relating DOM composition and watershed land use became apparent. A greater abundance of N- and S-containing molecular formulae were identified in rivers influenced by anthropogenic inputs, whereas rivers with primarily forested watersheds had DOM signatures relatively depleted in heteroatomic content. A strong correlation between cropland cover and dissolved black nitrogen was established when focusing specifically on the pyrogenic class of compounds. This study demonstrated how changes in land use directly affect downstream DOM quality and could impact C and nutrient cycling on a global scale.
  • Article
    Full-text available
    There is a growing need for environmental screening of natural waters in the Athabasca region of Alberta, Canada, particularly in the differentiation between anthropogenic and naturally-derived organic compounds associated with weathered bitumen deposits. Previous research has focused primarily upon characterization of naphthenic acids in water samples by negative-ion electrospray ionization methods. Atmospheric pressure photoionization is a much less widely used ionization method, but one that affords the possibility of observing low polarity compounds that cannot be readily observed by electrospray ionization. This study describes the first usage of atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (in both positive-ion and negative-ion modes) to characterize and compare extracts of oil sands process water, river water, and groundwater samples from areas associated with oil sands mining activities. When comparing mass spectra previously obtained by electrospray ionization and data acquired by atmospheric pressure photoionization, there can be a doubling of the number of components detected. In addition to polar compounds that have previously been observed, low-polarity, sulfur-containing compounds and hydrocarbons that do not incorporate a heteroatom were detected. These latter components, which are not amenable to electrospray ionization, have potential for screening efforts within monitoring programs of the oil sands. Graphical Abstract ᅟ
  • Article
    In this study, the octanol-water distribution ratios (DOW, i.e. apparent KOW at pH 8.4) of 2114 organic species in oil sands processing water were estimated by partitioning to polydimethylsiloxane (PDMS) coated stir bars and analysed by ultrahigh resolution orbitrap mass spectrometry in electrospray positive (+) and negative (-) ionization modes. At equilibrium, the majority of species in OSPW showed negligible partitioning to PDMS (i.e. DOW <1), however estimated DOW's for some species ranged up to >100,000. Most of organic acids detected in ESI- had negligible partitioning, although some naphthenic acids (O2- species) had estimated DOW ranging up to 100. Polar neutral and basic compounds detected in ESI+ generally partitioned to PDMS to a greater extent than organic acids. Among these species, DOW was greatest among 3 groups: up to 1000 for mono-oxygenated species (O+ species), up to 127,000 for NO+ species, and up to 203,000 for SO+ species. A positive relationship was observed between DOW and carbon number, and a negative relationship was observed with the number of double bonds (or rings). The results highlight that non-acidic compounds in OSPW are generally more hydrophobic than naphthenic acids and that some may be highly bioaccumulative and contribute to toxicity.
  • RationaleApproximately 1 billion m3 of oil sands process-affected water (OSPW) is currently stored in tailings ponds in Northern Alberta, Canada. The dissolved organic compounds in OSPW have been termed a supercomplex mixture of bitumen-derived substances and continuing efforts to understand its underlying chemical composition are important for evaluating its environmental hazards.Methods Packed column supercritical fluid chromatography (SFC) was applied to OSPW analysis for the first time. By combining four columns in series (each 25 cm × 4.6 mm I.D., 5.0 µm bare silica) approximately 80,000 plates were achieved on a 1 m column. Using a simple fixed restrictor, the SFC eluent was coupled directly to ultrahigh-resolution orbitrap mass spectrometry (SFC/Orbitrap-MS).ResultsSFC/Orbitrap-MS, with positive and negative atmospheric pressure chemical ionization (APCI +/–), revealed the partial or full chromatographic separation of isomers for a wide array of chemical species, including naphthenic acids (CnH2n + ZO2) and unknown sulfur- and nitrogen-containing molecules. For smaller compounds (e.g. naphthenic acids where n ≤10), or for larger structurally constrained compounds (e.g. C16 naphthenic acid with 9 double-bond equivalents), apparent baseline resolution of many isomers was possible. Isomer-specific MS/MS experiments furthermore allowed characterization of functional groups in novel species. For example, in APCI+ mode, up to 16 isomers of C6H11ON were revealed to have amide and amino functionalities.Conclusions This combination of high efficiency chromatography and ultra-high mass resolution detection resulted in a powerful method with capabilities for characterizing or 'fingerprinting' unknown species with little interference. The method has great promise for environmental monitoring and forensics in the oil sands region, as well as for further studies on the composition of dissolved organic compounds in OSPW. Copyright © 2015 John Wiley & Sons, Ltd.
  • Article
    The objective of this study was to identify chemical components that could distinguish chemical mixtures in oil sands process-affected water (OSPW) that had potentially migrated to groundwater in the oil sands development area of northern Alberta, Canada. In the first part of the study, OSPW samples from 2 different tailings ponds and a broad range of natural groundwater samples were assessed with historically employed techniques as Level-1 analyses, including geochemistry, total naphthenic acids (NAs) and Synchronous Fluorescence Spectroscopy (SFS). While these analyses did not allow for reliable source differentiation, they did identify samples containing significant concentrations of oil sands acid extractable organics (AEOs). In applying Level-2 profiling analyses using electrospray-high-resolution mass spectrometry (ESI-HRMS) and comprehensive multidimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOF/MS) to samples containing appreciable quantities of AEOs, differentiation of natural from OSPW sources was apparent through measurements of O2:O4 ion classes ratios (ESI-HRMS) and diagnostic ions for two families of mono-aromatic acids (GC×GC-TOF/MS). The resemblance between AEO profiles from OSPW and profiles from groundwater sampled beneath the Athabasca River adjacent to two tailings ponds offers the strongest direct evidence to date of OSPW migrations beyond containment systems and entering into the Athabasca River system.
  • Article
    The developments of oil sands activities in western Canada have increased the need for improved risk assessment and monitoring of water quality in surface and ground waters. Efforts have focused on the monitoring of naphthenic acids as principal toxicants of oil sands processed waters (OSPW). The complexity of naphthenic acids (NAs) has led to a surge in research to study their occurrence, fate and aquatic toxicity along with increased efforts to better characterize components in environmental samples. Developments in selective solvent extraction combined with negative-ion electrospray Orbitrap mass spectrometry are shown to be well-suited for the characterization of NAs and naphthenic acid fraction compounds (NAFCs) in Athabasca basin OSPW. Detailed characterization of the mixtures is critical for development of methods for the analyses of NAs and NAFCs. Improved methods for the characterization of NAFCs in turn will help improve the understanding of their measured toxicity, fate and transport in the environment.