This study examined water quality in a small residential wetland in Spokane, Washington. Water samples were taken from sites along the drainage gradient leading to the wetland and within the wetland. Concentrations of ions like magnesium and sodium increased from upstream to within the wetland, likely due to evapoconcentration. While concentrations of major ions accumulated in the wetland, concentrations of potential heavy metals like lead and zinc remained below EPA aquatic life standards. The results indicate the wetland shows no evidence of geochemical hazards from surrounding anthropogenic activities like vehicle traffic or land use.

1. Water Quality in a Residential Wetland Area (Spokane, WA)
Brandon Kautzman; Max Barnett; Carmen A. Nezat
Department of Geology, Eastern Washington University
Abstract
This study examines water quality of a small wetland area in an urban area in
Spokane Washington. Wetlands can serve as a sink for heavy metals such as lead,
zinc and copper. The wetlands lie on a moderately graded hill surrounded by roads,
homes and businesses. Anthropogenic sources such as vehicle traffic, lawn
fertilizers, and road deicer are known to add metals and nutrients to the surrounding
environment. We set out to discover if there were any potentially harmful metals
coming into the wetlands from the surrounding areas through runoff. Water at
several sites near the roadway, leading to, and in the wetland was tested for pH,
alkalinity and various element concentrations. Several dissolved ions were found in
higher concentrations in the wetlands and shallow waters around the wetlands. For
example, the magnesium and sodium concentrations upstream from the wetland
were 17 mg/L and 24 mg/L, respectively, whereas, in the wetland these values
reached 27 mg/L and 73 mg/L, respectively. This increase in major ion
concentrations is likely the result of evapoconcentration. No metals listed in EPA’s
aquatic life criteria (e.g., lead and zinc) for water quality were found in elevated
concentrations.
Introduction
A small wetland area on the upper South Hill
in Spokane Washington is located near busy
roads, farmland, and housing. These factors
are known to be potential sources of trace
metals such as Pb, Cd, Cu, and Zn (Zhao et
al., 2010). Trace metals such as these can
act as micro-pollution and be hazardous to
their environment (Göbel 2006). The purpose
of this report is to investigate the levels of
certain qualities in these wetlands to see if
they are adversely affected by this
anthropogenic activity. Very little research
supports metal accumulation and toxicity in
wetland areas (Muthukrishnan 2010). Our
hypothesis is that the metal concentrations
will increase along the pathway to the
wetlands with the wetlands themselves
containing the highest concentrations.
Sampling Sites
Sampling sites were located along the drainage gradient that ran next to high traffic roads,
active farmlands, and housing developments. We sampled from two of the three basins in the
wetland area, which ranged from centimeters to a few meters in depth.
Methods
1.Eight samples were collected in the fall,
2015. Temperature and pH were tested in
situ.
2.Samples were collected in pre-washed
bottles: water-washed (for alkalinity
titrations) and nitric acid (for metal
analysis).
3.Collected samples were transported
and tested for conductivity and alkalinity
in lab using Vernier equipment.
4.Metal concentrations were analyzed
using an Inductively Coupled Plasma
Optical Emission Spectrometer (ICP-
OES).
Brandon (top) samples from the
shoreline of the wetland area.
The close proximity of housing
is shown in relation to our
sample sites. The highway (not
shown) is approximately 50 ft
from this location.
Max (right) prepares the
samples to be tested in the ICP-
OES.
Results
Figure 1. Samples were taken on a gradient with slow moving water. The concentrations of metals
increased as we approached the wetland and were found to be highest in the wetland.
Figure 2. We observed correlation between magnesium concentration and
total dissolved solids (TDS), or conductivity. Correlation of the sample from 9-
Nov deviates. Sodium did not show the same correlation with conductivity.
Highlighted samples show the increase in concentration and decrease in
conductivity between sample dates.
Discussion
•Figure 1 shows some that major ions (Ca, Mg, K) accumulate in the
wetlands. Concentrations of trace elements (Pb, Zn) were below the
aquatic life criteria in the wetland.
•Both sodium and magnesium concentrations showed an increase at
the elementary school location a week after the initial sampling.
Magnesium showed a strong correlation to conductivity with the initial
samples but this correlation was broken for the school samples the
following week. Sodium did not show a strong correlation on either
sampling date. There was light stormy weather during the one week
period that added storm water runoff.
•Our results fell below the EPA aquatic life criteria for lead and zinc.
The concentrations of major alkali and alkaline earth metals remained
somewhat constant as we sampled down gradient towards the
wetland. We observed accumulation of the metals in the wetland
samples, which suggests evapoconcentration. Based on our analysis,
there is no evidence of any geochemical hazard to aquatic life in this
wetland.
Conclusions
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Analyzers, ICP Spectrometers, XRF Spectrometers for Elemental Analysis, http://www.spectro.com
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Bibliography
The ICP-OES
The diagram to the left illustrates the
schematics and process through which
the samples are analyzed. Each
sample must be prepared with 0.1 M
HNO3 to assist in the separation of
elemental metals. The samples are
vaporized, argon gas is added, and a
plasma interface superheats the gas
and sample, and sends the sample
through an optical analyzer. The
amount of metals present is able to be
detected by the spectrum of light
produced by the superheated gas.
Element Chronic (μg/L) Acute (μg/L) Range Analyzed (μg/L)
Pb 2.5 65 <LOD - <LOQ
Zn 120 120 <LOD - 50
Table 1. The results of our analysis for lead and zinc compared to the EPA
aquatic life criteria. Lead LOD= 3μg/L, LOQ= 10 μg/L. Zinc LOD= 4 μg/L.
Lead and Zinc Compared to EPA Aquatic Life Standards
This drain cover is located at one of the
testing sites near the intersection of
Glenrose Road and 57th
Avenue at the
base of Browne Mountain. The cover is
stamped with the text, “outfall to
stream, dump no pollutants.” The
stream in reference is located on the
north side of the school where our
second sampling site is located.