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Running head: ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 1
Distribution of Arsenic, Lead, Manganese and Nickel in Possession Sound with Relation to
Snohomish River Discharge
Laura Glastra
Ocean Research College Academy,
EvCC
Spring 2015
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 2
Abstract
The Snohomish River estuary system is influenced by fresh water sources as well as
exchange with coastal waters. There are many anthropogenic and natural activities in the estuary
that may lead to input of heavy metals such as arsenic, lead, manganese, and zinc. Depending on
the concentration, heavy metals may pose health risks to marine organisms as well as humans
exposed to the metals. Samples of sediments from two locations in Possession Sound were
expected to show variation due to different sediment characteristics, depth, and proximity from
the Snohomish River. It was hypothesized that with increasing seasonal river discharge, there
would be corresponding increases of heavy metal concentration. Statistical analysis comparing
metal concentration and river discharge did not show a strong linear correlation. This suggests
that other internal processes are occurring within the estuary. Continued monthly sampling
cruises, and future research comparing other chemical processes should provide insight on
influences of metal mobility.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 3
Distribution of Arsenic, Lead, Manganese and Nickel in Possession Sound with Relation to
Snohomish River Discharge
Heavy metals exist in both particulate and dissolved phases in estuarine systems
(Fukunaga & Anderson, 2011). Fluvial and riverine environments such as estuaries lead to the
dispersal of trace elements such as heavy metals, which makes it increasingly difficult to track
the sources of the metals (Bird, 2011). Tracing the source of contamination is further
complicated in urban environments due to the fact that heavy metals are continuously
accumulating because of anthropogenic activities (Luo, 2015). Various degrees of absorption
efficiency lead to bioaccumulation of heavy metals in organisms that inhabit aquatic
environments (Fukunaga & Anderson, 2011). Furthermore, pollution of heavy metals can
influence vegetative assemblage structure as well as plant productivity. Soils play a crucial role
in supporting estuarine systems, and affect the degree to which plants and animals may be
contaminated. More specifically, soils are involved in biochemical transformations, the cycling
of elements, filtration of water, and supporting plants and infrastructure of the ecosystem (Luo,
2012). The purpose of this study is to outline any spatial trends that may exist in heavy metal
concentration within the Puget Sound estuarine system. Data will be analyzed at two sites that lie
in a smaller body of water, Possession Sound, which is within the greater Puget Sound (Figures 1
and 2). These heavy metals may affect not only marine organisms and the local estuary, but also
be related to the health of humans and other organisms. It is hypothesized that heavy metal
concentrations will be higher at the Buoy site than at Mukilteo. This is hypothesized because
sediment is shallower at Buoy, which allows for more deposition of heavy metals. It is also
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 4
predicted that heavy metal concentrations at each location will increase correspondingly with
increases in seasonal river discharge.
Sources of Influence
There are various anthropogenic sources contributing to heavy metal contamination in
estuaries and marine ecosystems. Sources of metals can be traced back to long-term
industrialization and rapid urbanization. Long-term industrialization is defined by mining,
metallurgy, and fossil fuel combustion, while rapid urbanization consists of traffic and municipal
solid waste (Luo, 2015). In British Colombia long-term industrialization of leaded gasoline led to
heavy metal contamination of lead, zinc, copper, and cadmium. The study concluded that the
source of contamination was lead because the chronology of its isotope in sediment samples
correlated with gasoline consumption around the Strait of Georgia Basin (Macdonald,
Macdonald, O’Brien, & Gobeil, 1991). Another long-term industrialization source leading to
heavy metal contamination was activity at the Tacoma Copper Smelter throughout the 19th and
20th century (Kuo, Louchouarn, Herbert, Brandenberger, Wade, & Crecelius, 2011). In Pakistan,
rapid urbanization is thought to have led to wastewater contamination. One of these sources of
heavy metals in estuaries is thought to be wastewater contamination from various anthropogenic
causes as well as natural sources. Some of the natural contributors are from the erosion and
weathering of ore deposits and bedrock materials. The noted anthropogenic sources contributing
to heavy metal accumulation are various industrial processes, waste disposal, agricultural
practices, and mining. Additionally, emissions from vehicular traffic are thought to have led to
the atmospheric deposition and emissions of heavy metals that have been transported with rain
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 5
and storm water. If this water is used for irrigating crops in the area, it poses a potential threat to
humans unless it has been treated prior to irrigation (Khan, Malik, & Muhammad, 2013).
Sources, Movement, and Affects of Specific Heavy Metals
Arsenic. There are various sources that may contribute to arsenic in the environment.
While arsenic can be used in lead-acid batteries for automobiles and in its organic form as a
pesticide in some animal feeds, these sources do not greatly contribute to anthropogenic levels in
the environment. It is also used as a preservative on pressure-treated wood in the form of copper
chromated arsenate (CCA), but this only contributes to low levels of arsenic exposure. The
smelting and mining of copper and lead ores contribute more heavily to arsenic emissions.
Arsenic can also be released into the atmosphere by coal-fired power plants and incinerators
(Toxicological profile for arsenic, 2007).
Once released into the environment, arsenic cannot be destroyed. It can only change form
by becoming attached to or separated from other particles. Smaller particles that may come from
power plants and combustion processes are capable of remaining suspended in air for longer
durations. These particles may be removed from the air by rain, snow, or falling. Sticking to
other particles in water or sediment then transports them. Many arsenic compounds dissolve in
water. Yet, the majority of them remain located in soil/sediment. This is where the larger
particles of arsenic are generally located. Arsenic in aquatic ecosystems is generally so tightly
bonded with other particles and materials that plants and animals are unable to take it in.
However, various species of fish and shellfish can take in an organic arsenic called arsenobetaine.
The arsenobetaine accumulates in tissues, but has not been found to be harmful (Toxicological
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 6
profile for arsenic, 2007). But, seafood is listed as the primary contributor of arsenic exposure
through food in the Toxicological Profile for Arsenic.
In an attempt to trace arsenic transport routes in estuarine systems, a research team
collected data from 11 different sites during seven sampling cruises from 1997-2001. Because
the Scheldt estuary is well mixed, only surface samples of water were taken to analyze for
suspended and particulate arsenic particles. The research showed that increases of arsenic
corresponded with increases of river discharge, especially during flood times in the winter. In
summer, as river discharge decreased during dry periods, the arsenic values decreased as well. It
was also found that movement of arsenic particulates correlated with the movement of suspended
particulate matter. Therefore, suspended particulate matter could then be used to trace arsenic for
future studies. Another finding from the research showed that arsenic tended to settle in lower
salinity areas that had greater fluxes of sedimentation (De Gieter, M., Elskens, M., & Baeyens,
W, 2005).
The Handbook of Arsenic Toxicology has stated that arsenic exposure to humans is a
worldwide concern. Exposure to humans can occur through drinking, eating, and inhalation
(Ramasamy & Lee, 2015). Exposure during pregnancy may lead to impaired growth or fetal
death as it crosses the placenta. Arsenic exposure at this stage of development correlates with
lower scores on tests of cognitive function (Liua, McDermottb, Lawsona, & Aelion, 2010). Even
in stages of adulthood, arsenic may affect neurological function and reproductive health
(Ramasamy & Lee, 2015). Inorganic arsenic may lead to skin lesions, skin cancer, and
differences in patterns of the skin if exposed for long periods (Toxicological profile for arsenic,
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 7
2007). Circulatory and peripheral nervous disorders may also develop if exposed at low
concentrations over a long period of time. The Department of Health and Human Services
(DHHS), International Agency for Research of Cancer (IARC), and Environmental Protection
Agency (EPA) have all declared inorganic arsenic to be a human carcinogen. It has been linked
to increased risk of cancer in the liver, bladder and lungs. If inorganic arsenic is swallowed, it
may cause decreased red and white blood cell production, abnormal heart rhythms, and blood
vessel damage. These results may then lead to symptoms such as fatigue, bruising, and nerve
damage. If taken orally at a high enough dose, arsenic poisoning can be lethal (Toxicological
profile for arsenic, 2007).
Lead. The United States (U.S.) previously used tetraethyl and tetramethyl lead to
increase the octane rating of gasoline. Tetraethyl lead is still in use today for off-road vehicles
and airplanes. Presently, the largest use of lead is for storage batteries that are used in vehicles.
Pipes, weights, shot and ammunition, cable covers, and sheets used to shield humans from
radiation have also been known to contain lead. Lead is still mined in the U.S., though primarily
in Alaska and Missouri. Mining and other industries are contributors to the amount of
anthropogenic lead in the environment. Some industries such as lead-acid-battery manufacturing
and brass and bronze foundries release lead into the air. It can also be released into the air by
burning solid waste, coal, or oil containing lead. Furthermore, exhaust from workroom air,
degradation of lead-painted surfaces, fumes and exhaust from lead gas, and volcanoes and
cigarette smoke may release lead into the atmosphere. Lead is removed from the air by rain,
snow, or its particles eventually falling on land and/or surface waters. Another way lead can
enter aquatic systems is through wastewater from iron, steel, and lead producing industries,
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 8
urban runoff, and piles. This may affect humans if water that has been untreated is being
consumed or used to water crops. Humans can also be exposed to lead if they work at a lead
smelter, refineries, rubber products and plastic industries, soldering, steel welding and cutting
operations, battery manufacturing plants, lead compound manufacturing industries, or if they are
a construction and/or demolition worker (Toxicological profile for lead, 2007).
Metallic lead can only change its state or form because it is resistant to corrosion. If water
is acidic, there is the risk that it may result in lead pipes or solder releasing lead into the
environment. This is problematic because lead released into the environment may remain stuck
to particles in water or soil for many years. Lead that sticks to particles in soil will persist and
generally remain on the upper layer of soil (Toxicological profile for lead, 2007). The chemical
forms of lead were studied in the Pearl River Estuary using sequential chemical extraction
methods from samples of sediment cores. These allowed researchers to compare isotopes and
trace whether they were natural or anthropogenic. Researchers on this team compared the metals
of study to five geochemical terms that may have influenced the movement of lead in the estuary.
These terms were: exchangeable, bound to carbonate phase, bound to iron-manganese oxides,
bound to organic matter, and residual metal phase. In the estuary, the chemical form of the metal
easily influences lead mobility and solubility. It was found that lead increased toward the upper
regions of sediment, which were associated with iron-manganese oxides, residuals, and organic
fractions of the cores. These recent fractions suggest that the abundance of lead in the estuary is
due to rapid urbanization and industrialization (Li, X., Shen, Z., Wai, W.H., & Li, Y-S., 2001).
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 9
Most lead that plants and animals ingest through the air, water, and soil, will pass through
their systems (Toxicological profile for lead, 2007).
Lead can accumulate in fetal tissues beginning at 12 weeks of pregnancy. While the
general adult population is thought to absorb only 1-20 percent of ingested lead, pregnant women
are believed to absorb up to 70 percent of ingested lead (Toxicological profile for lead, 2007;
Liua et al., 2010). Exposure to a fetus leads to the risks of miscarriage, premature birth, and
lower average birth weights (Toxicological profile for lead, 2007). Young children are still more
vulnerable to lead absorption than adults with approximately 32 percent leaving their bodies as
waste (Toxicological profile for lead, 2007). It is thought that low-level lead exposure at a young
age may lead to neuro-developmental problems such as mental retardation and developmental
delays (Liua et al., 2010; Toxicological profile for lead, 2007). It may also affect a child’s
physical growth. Slower mental development due to exposure in the womb, infancy, or early
childhood correlates with lower intelligence later on in childhood. Furthermore, research
suggests that these effects persist beyond the stages of childhood. If swallowed at slightly higher
amounts, children may experience effects on their blood, development, and behavior. Finally, if
swallowed in large amounts, children may experience anemia, kidney damage, colic (severe
stomach pain), muscle weakness, and brain damage. These results may ultimately lead to cause
of death (Toxicological profile for lead, 2007).
It has been shown that lead exposure primarily targets the nervous system in both
children and adults. In adults, high levels of exposure may lead to severe and potentially lethal
damage of the brain and/or kidneys. High-level exposure in men specifically may damage organs
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 10
related to the production of sperm. It may also contribute to weakness of the fingers, wrists, or
ankles. Smaller exposure is linked to increases in blood pressure and anemia. There is, however,
no conclusive proof that exposure to lead is carcinogenic to humans (Toxicological profile for
lead, 2007).
Manganese. Manganese is released into the environment during manufacturing processes,
through the use and disposal of manganese based products, due to the actions of industries, and
mining. It can also be released into the air through automobile exhaust since some gasoline
contains manganese additives. Some gases that easily degrade may release manganese into the
environment when exposed to sunlight. Humans may also be exposed to manganese if they are
working or welding in a factory where steel is produced. However, the primary source of
exposure is through foods such as grains, beans and nuts, and to heavy tea drinkers. Once
manganese is released into the environment it cannot be broken down. It can only change form,
or become attached to or separated from other particles. Once in water, it tends to attach itself to
water particles or settle in sediment. The type of soil and chemical state of manganese then
determines the movement of manganese in soil (Manganese, 2008).
From January to December in 1999, researchers sampled for manganese and barium in
the Tillamook Bay Estuary in the Pacific North West. Sampling methods were conducted using a
Niskin bottle deployed to a depth of one meter for dissolved elemental samples. These were later
used to calculate suspended particulate matter, which may influence movement of the manganese
particulates. Surface sediments were collected using a surface sediment grab sampler. Samples
were later frozen and homogenized prior to testing for metal concentration. To analyze input and
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 11
exchange from rivers and coastal waters, a box model was utilized as a visual representation. The
research showed that as the metal concentrations varied seasonally, they correlated with
suspended particulate materials. It was concluded that adsorption and desorption reactions of
suspended particulates determined seasonal variance of the manganese. Seasonal variance of
manganese was also influenced by benthic sources. Furthermore, the dissolved manganese
values correlated with river discharge rates during winter. This was not true for the other seasons.
It was hypothesized that the lack of correlation could be attributed to internal estuarine processes
such as transport across a sediment-water interface (Colbert, D. & McManus, J., 2005).
Manganese may enter the body through inhalation and ingestion. Miniscule amounts may
enter the body through dermal contact. Of the manganese that enters the body, most will leave
through feces within several days. If a large amount is inhaled, it can lead to lung irritation and
potentially cause pneumonia. Humans may be exposed to manganese if they ingest fish or
shellfish. It has been reported in the journal of Food and Chemical Toxicology that chronic
exposure to manganese through these foods can lead to psychological and neurologic effects that
resemble Parkinson’s disease (Olmedo, Hernandez, Pla, Femia, Navas-Acien, & Gil, 2013). High
exposure to children may affect the brain and lead to behavioral changes, which can decrease
learning capabilities. It is not known whether these changes are permanent in children, nor if
children are more sensitive to manganese exposure than adults. High-level exposure in adults
primarily affects the nervous system. This can lead to behavioral changes and slow/clumsy
movements. Nervous system affects generally occur in workers who are exposed to levels about
one million times higher than those found in the environment. High exposure to men can result
in a loss of sex drive and damage to sperm. Lower levels of exposure may result in slower hand
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 12
movements. The EPA has not yet been able to conclude whether excess manganese is
carcinogenic to humans (Manganese, 2008).
Nickel. There are no nickel mining operations presently occurring in the U.S. Most nickel
used in the U.S. is imported from Canada or Russia. Nickel compounds may be used for nickel-
plating, catalysts, color for ceramics, and in the production of some batteries. It may be released
into the atmosphere by mining, oil and coal burning power plants, and trash incinerators. It may
also be released by industries since some discharge wastewater that may contain nickel
(Toxicological profile for nickel, 2005). Nickel released into water can be in its dissolved form
or attach to suspended material in the water. It may be released through pipes into groundwater
under more acidic conditions that can increase the mobility of nickel. The nickel released from
power plants may attach to small particles that can settle as dust or be washed out of the air by
rain and/or snow (Toxicological profile for nickel, 2005).
Nickel distribution, speciation, and particle-water interactions were monitored through
the uptake and release of a beta-emitting nuclide, 63Ni, through the use of suspended estuarine
particles. The data show that there were seasonal variations in nickel concentration due to both
natural and anthropogenic activities, which were sources of nickel. River flow was also found to
contribute to seasonal variation of nickel in the estuary. With increased salinity, it was found that
there was also increased particulate reactivity. Salinity, in addition to suspended particles,
influences the behavior of nickel in estuarine systems. In conditions of higher salinity, nickel
located in sediment had little tendency to desorb, or be released (Martino, Turner, & Nimmo,
2004).
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 13
Fish are not known to accumulate nickel in their bodies, but some plants may absorb the
metal (Toxicological profile for nickel, 2005). The major contributor to nickel exposure in
humans is food. Humans can also be exposed to it through dermal contact with water, soil, and
other metals containing nickel as well as by breathing air, drinking water, and smoking tobacco.
If water containing greater than 250 parts per million (ppm) of nickel is ingested, humans may
experience stomach aches, increased counts of red blood cells, and increased protein in their
urine. Welding workers and other workers in some industries may inhale air containing high
amounts of nickel – this is when the most serious effects occur. Inhalation of nickel has been
known to cause chronic bronchitis, reduced lung function, and cancer of the lungs and nasal
sinus. The EPA has stated that nickel refinery dust and nickel subsulfides (the type generally
inhaled by workers) are carcinogenic to humans. Once nickel enters the human body, it tends to
accumulate in the kidneys. But, after entering the body it can make its way to any organ. Nickel
that accumulates in a female’s body be transferred to infants through breast milk and across the
placenta. The levels of nickel found in breast milk are similar to those found in cow’s milk and
soy based formulas. The DHHS has declared nickel metals to possibly be carcinogenic, and
nickel compounds to be a known human carcinogen. The IARC has declared metallic nickel to
possibly be a carcinogen, and some nickel compounds to definitely be human carcinogens
(Toxicological profile for nickel, 2005; Klein & Costa, 2015).
Methods
Field Methods
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 14
Underwater sediment samples were collected from June 2009 to March 2015 at site 1.) MUK,
just north of the Mukilteo ferry terminal and inactive fuel docks, and 2.) BUOY, to the southwest
of Everett. Each of these sites has been chosen because of their proximity to anthropogenic
activity. The heavy metals are found in sediments that are collected with a Ponar style grab at the
surface of the substrate. The trends of the substrate and type of sediment are later noted for each
sample in data collection logs. Heavy metal data was then compared to river discharge in ft3/s
through the database provided by USGS (United States Geological Survey).
Lab Methods
The Everett Environmental Lab analyzed samples for the presence of heavy metals including As,
Pb, Mn, and Ni. This process used modified Environmental Protection Agency (EPA) methods
6020 and 7471. Samples are analyzed through the use of a quadrupole inductively coupled
plasma mass spectrometer.
Results Arsenic
The average concentration of arsenic found at Buoy from 2009-2015 was 9.23 ppm. The
average value from the Mukilteo site was lower at 5.39 ppm (Figure 11). At Buoy, average
arsenic levels were highest during spring (10.12 ppm) and lowest during the fall (8.64 ppm)
(Figure 3). The values at Buoy averaged to 9.04 ppm during summer and 8.67 ppm in winter
(Figure 3). At Mukilteo, the highest average arsenic concentration was found in winter at 6.54
ppm with the lowest average value (3.19 ppm) being found in the summer (Figure 4). The second
highest average value of 5.41 ppm in Mukilteo was found during the spring, which was followed
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 15
by 5.27 ppm in the fall (Figure 4). Average trend values did not correlate between seasons at
Buoy and Mukilteo, but arsenic concentrations remained greater throughout the year at the Buoy
site than in Mukilteo.
Lead
From 2009-2015, the average concentration of lead at Buoy was 7.20 ppm, and 6.06 ppm
at Mukilteo (Figure 11). Values were highest on average at Buoy during the fall (7.83 ppm) and
lowest during the summer (6.68 ppm) (Figure 5). The next highest values at Buoy were 7.36 ppm
in the spring and 6.86 ppm in the winter (Figure 5). At Mukilteo, the highest average value
occurred in winter (9.93 ppm), and the lowest in summer (1.14 ppm) (Figure 6). Average values
in spring reached 5.79 ppm, which was followed by an average of 4.34 ppm in the winter (Figure
6). Trends for average high and low values did not correlate for lead concentrations between the
two sites. Average values per season remained consistently higher at Buoy than Mukilteo
throughout the year with the exception of values recorded in winter.
Manganese
Manganese values were an average of 268.16 ppm and 179.78 ppm at Buoy and Mukilteo
respectively from 2009-2015 (Figure 11). At Buoy, the average values were highest in spring
(293.87 ppm) and fall (260.15 ppm), and lowest in winter (259.97 ppm) and summer (235.24
ppm) (Figure 7). At Mukilteo, the highest average value of manganese (212.64 ppm) also
occurred during spring (Figure 8). Additionally, the lowest average manganese value (74.52
ppm) also occurred during summer at Mukilteo (Figure 8). The second highest average value at
Mukilteo was during the winter at 195.40 ppm, which was followed by 185.98 ppm in the fall
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 16
(Figure 8). Both locations had average highs during spring; 293.87 ppm at Buoy and 212.64 ppm
Mukilteo; and average lows during summer, 235.24 ppm at Buoy and 74.52 ppm at Mukilteo
(Figures 7 and 8). Average values at Buoy remained continually greater than those at Mukilteo
throughout the year.
Nickel
The average concentrations of nickel at Buoy and Mukilteo from 2009-2015 were 32.98
ppm and 24.57 ppm respectively (Figure 11). The highest average concentration of nickel, 35.73
ppm, occurred during spring (Figure 9). This was followed by 35.23 ppm in fall, and 30.12 ppm
in winter (Figure 9). The lowest nickel concentrations at Buoy occurred during summer and
averaged to 29.22 ppm (Figure 9). The same trends occurred for nickel at the Mukilteo site
(Figure 10). Mukilteo had an average of 29.22 ppm in spring, 27.51 ppm in winter, 28.71 ppm in
fall, and a low of 3.89 ppm in the summer (Figure 10). The lowest average nickel concentration
at Buoy (29.22 ppm in summer) was the same as the highest average concentration at Mukilteo
(29.22 ppm in spring) (Figures 9 and 10). Data of nickel concentrations from other seasons were
all greater at Buoy than at Mukilteo.
River Discharge
Snohomish River discharge from 2009-2015 averaged 11,794 ft3/s. Throughout those six
years, the highest recorded discharge from the river occurred during the winter of 2011 at 23,360
ft3/s (United States Geological Survey). Spring of 2010 held the lowest discharge rate of 4,996
ft3/s. The Pearson Coefficient, or correlation coefficient, measures the correlation between to
variables in a single number (r) ranging from positive to negative one. At Buoy, arsenic and
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 17
manganese had r-values of 0.188 and 0.134 respectively (Figures 12 and 16). Lead and nickel
had negative r-values at Buoy of -0.144 and -0.260 respectively (Figures 14 and 18). At the
Mukilteo site, all r-values were positive. The r-value of arsenic was 0.442, while the r-value of
manganese was 0.222 (Figures 13 and 17). Lead had an r-value of 0.438, and nickel had an r-
value of 0.034 (Figures 15 and 19). At the Buoy site, both the r-values for arsenic and manganese
were lower than those recorded at the Mukilteo site. The same trend was recorded for r-values
pertaining to lead and nickel.
Discussion
Arsenic
Arsenic concentrations were greater at Buoy than Mukilteo when comparing overall
average values from 2009-2015, and the maximum and minimum values at each site within this
time. The same trend was true when comparing the average concentrations of arsenic per season
at each location. However, maximum and minimum concentrations were not recorded during the
same seasons at both sites. Ergo, river discharge seemed to affect the sites differently, or had
little affect on the arsenic concentrations. When analyzing the Pearson Coefficient, Buoy had a
lower positive value than Mukilteo. This greater positive relationship at Mukilteo represents that
there was a higher correlation between increased river discharge and arsenic concentration than
there was at Buoy. Yet, Buoy still maintained greater arsenic concentrations than those measured
at the Mukilteo site. It is possible that other estuarine processes occurred internally. As well as
that suspended particulate matter may have influenced movement of arsenic in addition to the
river discharge (De Gieter, Elskens, & Baeyens, 2005). Suspended particulate matter was not a
part of the methods in this study.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 18
Lead
Lead concentrations remained greater at Buoy than Mukilteo when comparing overall
averages throughout the time from 2009-2015. The trend continued for average seasonal values
in spring, fall, and summer. However, during the winter, Mukilteo had a greater average lead
concentration that Buoy. This is most likely attributed to the outlier of 35.23 ppm measured
during the winter of 2011 at Mukilteo. Such an outlier could have come up if the Ponar grab hit a
leaded weight, or other source of lead from industry and fishing in the area, during sample
collection. Because of this outlier, it makes it difficult to analyze exactly the trends that occurred.
Including it in the data set, the data show that average maximum and minimum values did not
occur during the same seasons at Buoy and Mukilteo. This shows that river discharge did not
have the same influence on lead concentrations at the two sites. When looking to the Pearson
Coefficient, it can be seen that Mukilteo had a greater positive r-value than the Buoy site, which
had a negative r-value. This is the same trend that was seen with arsenic concentrations. The
greater positive value signifies that there was a stronger correlation between increased river
discharge and increased lead concentrations at Mukilteo than at Buoy. It is important to note with
such an outlier that correlation does not necessarily equate to causation. The negative r-value
recorded at Buoy shows that there was a small correlation between increased river discharge and
decreased lead deposition. It is possible that anthropogenic activity has more of an influence than
river discharge in determining deposition of lead in estuaries, which has been previously studied
using core samples from sediments (Li, Shen, Wai, & Li, 2001). This method was not available
during the time of this research.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 19
Manganese
Concentrations of manganese were greater at Buoy than Mukilteo when comparing
overall averages from 2009-2015 as well as average seasonal trends. Mukilteo and Buoy had the
same seasonal maximum and minimum values for samples of manganese. When analyzing the
Pearson Coefficient, both r-values for Mukilteo and Buoy were rather low positive values. This
means that the increased river discharge and increased manganese deposition did not have a
strong correlation. As with the other metals, though, Mukilteo had a stronger correlation than
Buoy did when compared to river discharge. The correlation at both sites was minimal, and does
not represent a strong connection between river discharge and manganese deposition. Previous
studies have analyzed suspended particulate matter, in addition to river discharge, and found that
adsorption and desorption reactions determined the seasonal variance of manganese
concentrations. The same study also found that benthic sources of manganese contributed to the
seasonal variance (Colbert & McManus, 2005). This research did not take into account
suspended particulate matter nor potential natural benthic sources of manganese along the
Snohomish River.
Nickel
As with the other three metals, the average concentration of nickel was greater at Buoy
than at Mukilteo. This was also true throughout each season. Maximum and minimum values
corresponded for each seasons between the two sites, which suggests similar influence from river
discharge. The Pearson Coefficient shows that there was a positive correlation between river
discharge and nickel deposition at Mukilteo, but a negative relationship between the two factors
at Buoy. Both r-values were the lowest of all metals for both sites. The low positive value at
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 20
Mukilteo means there was the least amount of correlation between river discharge and nickel
deposition than any other metal at the site. The lowest negative value at Buoy shows there was
the strongest correlation between increased river discharge and decreased nickel deposition than
any other metal at Buoy. Studies have previously shown that seasonal variations in nickel
concentration can be attributed to natural and anthropogenic activities that are nickel sources.
But, this study also found that river flow contributed to seasonal variation. Additionally, salinity
and suspended particles seemed to influence nickel activity. In higher salinities, nickel in
sediment had little tendency to release, so higher concentrations would be located in sediment of
higher salinity areas (Martino, Turner, & Nimmo, 2004). This study did not assess salinity as an
influence to nickel mobility, nor suspended matter.
Limitations of Methods and Data
Data was collected during various sampling cruises that attempted to portray a seasonal
spread of the data. However, due to weather, some cruises in the past had to be cancelled as a
safety precaution. This results in there being more data for some seasons than others, which
means that not all seasons have an equal portrayal of data averages. Some seasons, such as
summer, may portray a more accurate trend than others. Furthermore, sediment consistency at
Mukilteo often complicated the sampling process that used the Ponar style grab. The result is that
there is much more data, from all seasons, at Buoy than there is at the Mukilteo site.
Once samples were collected, standard laboratory methods were followed, and samples
were sent to the Everett Environmental Lab. Dates recorded portray when samples were analyzed
for metal concentration at the Environmental Lab, not when samples were originally taken. The
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 21
gap between these two dates typically spans about one month. Because samples were compared
to river discharge that is dependent on date, the samples were compared to average river
discharges the month prior to the date recorded at the lab. This was in an attempt to align the
river discharge average of the month to the time sediments were collected on sampling cruises.
This approximation decreases the level of accuracy in displaying the correlation between river
discharge and metal concentration.
Conclusion
The hypothesis that arsenic concentrations would be greater at Buoy than Mukilteo was
supported when comparing overall average values from 2009-2015, and the maximum and
minimum values at each site within this time. This hypothesis was also supported when
comparing the average concentrations of arsenic per season at each location. The same
hypothesis was supported for lead concentrations between the two sites, with the exception of
Mukilteo in the winter. For both manganese and nickel, the hypothesis was also supported.
Higher average value trends continued for both of these two metals at Buoy throughout each
season individually as well.
The second hypothesis that metal concentrations would increase with increased river
discharge was not strongly supported. To show the strength of linear correlation between the two
variables, the Pearson Coefficient was used. R-values varied for each metal, with arsenic at
Mukilteo showing the strongest correlation. However, all values calculated for both sites were
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 22
not significant enough to show a strong, definite connection between increased river discharge
and increased metal concentration. In fact, some metals at Buoy had negative r-values. A
negative value represents the opposite of the original hypothesis, and shows that increased river
discharge in fact led to decreased metal concentration. Lead and nickel both reported negative r-
values at Buoy, while manganese and arsenic had weak linear correlations. Therefore, the
hypothesis that increased seasonal variance of river discharge would correlate with increased
seasonal variance of heavy metal concentrations was not supported. Further research would need
to be conducted in order to determine the influences of heavy metals in the Snohomish River
estuarine system. Some studies suggest that salinity may affect the mobility and suspension of
metals (Martino, Turner, & Nimmo, 2004). Ergo, this would be another factor to take into
account when analyzing metal concentrations in forthcoming studies. Furthermore, some studies
suggest that heavy metal variance in estuaries can be attributed to anthropogenic activities rather
than natural sources. This could potentially be tested through the use of isotopes and core
sampling, especially for lead (Li, Shen, Wai, & Li, 2001). Various studies also suggest that
internal estuarine processes such as suspended particulate matter greatly influence the movement
and processes of many heavy metals (De Gieter, Elskens, & Baeyens, 2005; Colbert & McManus,
2005; Martino, Turner, & Nimmo, 2004). Analysis of salinity and suspended particulate matter
are two prospective factors that could be duplicated for upcoming studies of heavy metal
mobility in estuaries.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 23
Appendix
Figure 1: Puget Sound
Figure 2: Possession Sound
Buoy
Mukilteo
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 24
Figure 3
Figure 4
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 25
Figure 6
Figure 5
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 26
Figure 7
Figure 8
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 27
Figure 9
Figure 10
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 28
Average concentration 2009-2015
Buoy Mukilteo
As 9.22695 5.38847368
Pb 7.19985 6.05721053
Mn 268.161 179.777158
Ni 32.97585 24.5731053
Figure 11
0
2
4
6
8
10
12
0 5,000 10,000 15,000 20,000 25,000
Concentration(mg/Kg=ppm)
RiverDischarge
ArsenicatBuoy
Figure 12: Pearson Coefficient showing strength of linear correlation between arsenic concentration and river discharge at Buoy.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 29
0
2
4
6
8
10
12
0 5,000 10,000 15,000 20,000 25,000
Concentration(mg/Kg=ppm)
RiverDischarge
ArsenicatMukilteo
Figure 13: Pearson Coefficient showing strength of linear correlation between arsenic concentration and river discharge at the Mukilteo site.
0510152025303540
0 5,000 10,000 15,000 20,000 25,000Concentration(mg/Kg=ppm)
RiverDischarge
LeadatBuoy
Figure 14: Pearson Coefficient showing strength of linear correlation between lead concentration and river discharge at Buoy.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 30
0510152025303540
0 5,000 10,000 15,000 20,000 25,000Concentration(mg/Kg=ppm)
RiverDischarge
LeadatMukilteo
Figure 15: Pearson Coefficient showing strength of linear correlation between lead concentration and river discharge at Mukilteo location.
050100150200250300350400
0 5,000 10,000 15,000 20,000 25,000Concentration(mg/Kg=ppm)
RiverDischarge
ManganeseatBuoy
Figure 16: Pearson Coefficient showing strength of linear correlation between manganese concentration and river discharge at the Buoy site.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 31
050100150200250300350400
0 5,000 10,000 15,000 20,000 25,000Concentration(mg/Kg=ppm)
RiverDischarge
ManganeseatMukilteo
Figure 17: Pearson Coefficient showing strength of linear correlation between manganese concentration and river discharge at Mukilteo location.
010203040506070
0 5,000 10,000 15,000 20,000 25,000Concentration(mg/Kg=ppm)
RiverDischarge
NickelatBuoy
Figure 18: Pearson Coefficient showing strength of linear correlation between nickel concentration and river discharge at Buoy.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 32
010203040506070
0 5,000 10,000 15,000 20,000 25,000Concentration(mg/Kg=ppm)
RiverDischarge
NickelatMukilteo
Figure 19: Pearson Coefficient showing strength of linear correlation between nickel concentration and river discharge at Mukilteo.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 33
References Bird, G. (2011 May). Provenancing anthropogenic Pb within the fluvial environment:
Developments and challenges in the use of Pb isotopes. Environmental International, 37, 802-819. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0160412011000389.
Colbert, D. & McManus, J. (2005 July). Importance of seasonal variability and coastal processes
on estuarine manganese and barium cycling in a Pacific Northwest estuary. Continental Shelf Research, 25, 1395-1414. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0278434305000622?np=y.
De Gieter, M., Elskens, M., & Baeyens, W. (2005 May). Fluxes and major transport routes of
Arsenic in the Scheldt estuary. Marine Chemistry, 95, 15-30. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0304420304001860?np=y.
Fukunaga, A., & Anderson, M. J. (2011 January). Bioaccumulation of copper, lead and zinc by
the bivalves Macomona liliana and Austrovenus stutchburyi. Journal of Experimental Marine Biology and Ecology, 396, 244-252. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S002209811000434X?np=y.
Hartnett, M. & Berry, A. (2010 January). Transport of lead in the Mersey Estuary: The
development of a novel approach to deriving partition coefficients. Advances in Engineering Software, 41, 84-91. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0965997808002159?np=y.
Khan, M.U., Malik, R.N., & Muhammad, S. (2013 November). Chemosphere, 93, 2230-2238.
Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0045653513010515.
Klein, C. & Costa, M. (2015). Specific Metals Chapter 48 – Nickel. Handbook on the Toxicology
of Metals (Fourth Edition), 2, 1091-1111. http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/B9780444594532000482?np=y.
Kuo, L., Louchouarn, P., Herbert, B.E., Brandenberger, J.M., Wade, T.L., & Crecelius, E. (2011
April). Combustion-derived substances in deep basins of Puget Sound: Historical inputs from fossil fuel and biomass combustion. Environmental Pollution, 159, 983-990. Retrieved from
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 34
http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0269749110005762.
Li, X., Shen, Z., Wai, W.H., & Li, Y-S. (2001 March). Chemical Forms of Pb, Zn and Cu in the
Sediment Profiles of the Pearl River Estuary. Marine Pollution Bulletin, 42, 215-223. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0025326X00001454?np=y.
Liua, Y., McDermottb, S., Lawsona, A., & Aelion, C.M. (2010 March). The relationship
between mental retardation and developmental delays in children and the levels of arsenic, mercury and lead in soil samples taken near their mother’s residence during pregnancy. International Journal of Hygiene and Environmental Health, 213, 116-123. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S1438463909001370?np=y.
Luo, X., et al. (2012 April). Trace metal contamination in urban soils of China. Science of The
Total Environment, 421-422, 17-30. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0048969711003779.
Luo, X., et al. (2015 May). Source identification and apportionment of heavy metals in urban soil
profiles. Chemosphere, 127, 152-157. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0045653515000880?np=y.
Macdonald, R.W., Macdonald, D.M., O’Brien, M.C., & Gobeil, C. (1991 September).
Accumulation of heavy metals (Pb, Zn, Cu, Cd), carbon and nitrogen in sediments from Strait of Georgia, B.C., Canada. Marine Chemistry, 34, 109-135. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/030442039190017Q?np=y.
Martino, M., Turner, A., & Nimmo, M. (2004 September). Distribution, speciation and particle-
water interactions of nickel in the Mersey Estuary, UK. Marine Chemistry, 88, 161-177. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0304420304000763?np=y.
Olmedo, P., Hernandez, A.F., Pla, A., Femia, P., Navas-Acien, A., & Gil, F. (2013 December).
Determination of essential elements (copper, manganese, selenium and zinc) in fish and shellfish samples. Risk and nutritional assessment and mercury–selenium balance. Food and Chemical Toxicology, 62, 299-307. http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/S0278691513006224?np=y.
ARSENIC, LEAD, MANGANESE, AND NICKEL IN POSSESSION SOUND 35
Puget Sound. (2015 June). Retrieved on 13 June 2015 from the Puget Sound wiki https://en.wikipedia.org/wiki/Puget_Sound.
Ramasamy, S., & Lee, J.S. (2015 January). Arsenic Risk Assessment. Handbook of Arsenic
Toxicology, 95-120. Retrieved from http://www.sciencedirect.com.ezproxy.everettcc.edu/science/article/pii/B9780124186880000046?np=y.
United States Geological Survey. (2015 June). Data inventory for Snohomish River near
Monroe, WA. Retrieved from http://waterdata.usgs.gov/nwis/uv?site_no=12150800. United States. 2005. Toxicological profile for nickel. Atlanta, Ga: U.S. Dept. of Health and
Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry.
United States. 2007. Toxicological profile for arsenic. Atlanta, Ga: U.S. Dept. of Health and
Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry. http://purl.fdlp.gov/GPO/gpo31622.
United States. 2007. Toxicological profile for lead. [Atlanta, Ga.]: U.S. Dept. of Health and
Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry. http://purl.fdlp.gov/GPO/gpo31474.
United States. 2008. Manganese. Atlanta, GA: Dept. of Health and Human Services, Public
Health Service, Agency for Toxic Substances and Disease Registry, Division of Toxicology and Environmental Medicine. http://purl.fdlp.gov/GPO/gpo24268.
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