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Atomic Absorption Analysis of Ken Lake Water

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Atomic Absorption Analysis of Ken Lake Water Powered By Docstoc
					                         Ken Lake Water Analysis
                         Envronmental Analysis, 2002-03
  Jon Clemens, Alan Arvidson, Heather Rankin, and Jeff Taisch
                 Jon Clemens, Individual Report, 11/14/02


Introduction
       Ken lake is located in NW Olympia, WA and is surrounded by the Lakemoor
residential development located just south of the Black Lake exit of Hwy 101. It coveres
a total area of over 1,000,000 square feet, and is about 6000 feet in perimeter. The
average depth of the lake is about 2.2 meters, measured over a period of five weeks. It is
used for recreation and has a large housing development along the shore. Formerly
known as Simmons Lake, it receives runoff from the surrounding yards and also receives
biocide treatments for vegetation control. These factors will greatly contribute to the
future direction of our analyses. There are floating docks at several locations on the lake.
We have hypothesized that certain chemicals from dock treatment products will show up
in further research. Research is continuing in these areas. Motor boats are not allowed on
the lake but there are canoes, rowboats and paddleboats that are frequently used for
recreational purposes.
       We are currently undertaking a chemical analysis of the lake water samples. As of
the present time, analyses have been done for the following: NO2-, NO3-, Cl-, SO4-, PO4-,
Na, and K. The alkalinity of the lake has also been monitored throughout our
investigatoin. In addition the these laboratory tests, several physical parameters of the
lake were measured while in the field. These include temperature, dissolved oxygen,
conductance, pH, visibility, and salinity. Certain characteristics of the lake have naturally
undergone changes during the course of our investigation and we expect these same
characteristics to remain unsettled in the future. For instance, the temperature has
dropped from an average of 16.2 C on 10/04/2002 to an average of 8.9 C on
11/08/2002. Mapping these changes in the lake composition is a major goal of our long
term research.
Clemens                                  Ken Lake                                           2



Materials and Methods
       During our sampling of lake water, we used a two-man plastic paddleboat to
navigate to the sampling sites. A secci disk was used for the visibility and depth
measurements and averages of these were taken across the lake. The Van Dorm water
sampling apparatus was used to take water samples from the various depths and transfer
them into the sample bottles. An 85D YSI meter measured the physical parameters of
temperature, dissolved oxygen, salinity, and conductance at 1 meter intervals. The
Oakton pH meter (model 35613) was used to determine an average pH for our lake since
no hypolimnion or epilimnion existed (the lake was holomictic). The samples were
collected and prepared for chemical analysis by the methods listed below in the AA
section. A Garman eTrex Summit GPS unit was used to mark are coordinates at the
sample sites. Vertical profiles of these parameters were produced using the graphing
feature of Microsoft Excel.
       Alkalinity titrations were carried out by titrating the water samples with 0.01601
M HCl to a pH of 4.50. The pH was monitored with the pH meter, and the alkalinity was
expressed in terms of mg/L CaCO3. We used a micropipette device to deliver the HCl in
order to get more precise results.
       The ion chromatograph was used to analyze for NO2-, NO3-, Cl-, SO4-, and PO4-.
Standards were prepared at 10, 1, and 0.25 mg/L concentrations of Cl-, NO2-, and NO3-
and 40, 4, and 1 mg/L concentrations of SO4- and PO4-. Logger Pro software was used to
integrate the voltage peaks for the anions in the column. Linear Regression analysis was
used to determine the concentrations of analytes in our samples. Ion chromatograph
results were obtained by Jeff Taisch and are included in the group report.


Results
       The vertical profiles can be seen in the following series of graphs in figure 1. The
average secci disk reading for Ken Lake was 2.2 m. The disk was visible to the lake
bottom at all locations. The average pH of the lake was 6.50 according to the samples
obtained at various depths and locations using the Van Dorm bottles. The average
alkalinity for Ken Lake water was 8.529 mg/L CaCO3 on 10/25/02 and 10.238 mg/L
Clemens                                   Ken Lake                                               3


CaCO3 on 11/08/02. Our data set can be viewed on Workspace on Masu in the
PRG_EA/Projects/Ken Lake folder.


Discussion
       It was interesting to note that the alkalinity of Ken Lake seemed to drop from
10/25 to 11/08. There are a couple of factors that could have contributed to this. First, it is
possible that the lake was undergoing a change in compisition during this time. However,
care shouild be taken in the future to always carry out the titrations as soon as possible.
The water samples taken on 10/25 were not titrated on the day they were collected, while
the ones collected on 11/08 were. In the future, all alkalinity titrations will be carried out
on the same day that they were collected.
       There is no eveidence of a chemocline on Ken Lake, nor of an epi- or hypo-
limnion according to the depth profiles. However, there is a small increase in
conductance and temperature at the bottom of the lake. Reasons for this could be organic
activity at the lake bottom or sediment contact with the YSI electrode. For this reason,
averaging our results for pH, temperature and other physical parameters was justified for
a description of the lake as a whole.
       Our future research is going to include further analysis of the methods explained
in the group report, which include anion and cation concentration analyses and alkalinity
titrations as well as monitoring physical parameters. We will branch out into searching
for possible pollutants originating from wood treatment products and biocide residue
byproducts. A more developed profile of Ken Lake can be generated once more data is
obtained.




Analysis of Ken Lake Water for Sodium and Potassium
Using Atomic Absorption Spectroscopy
Abstract
       The atomic absorption spectrometer can be used to analyze water samples
       for specific elements. In particular, we were interested in concentrations of
       Na and K present in water from Ken Lake in Olympia, WA. Sodium was
Clemens                                  Ken Lake                                            4


        found to be present in concentrations of 3.0 ppm and potassium was found
        to exist in concentrations of 1.2 ppm.

Introduction
        Currently, we have been unable to find documentation of past analyses of Ken
Lake for Na and K. However, we have found data of Thurston County well water and
have identified 3 wells within 1500 meters of the lake. Typical Thurston County
groundwater has Na concentrations of 6.5 mg/L and typical K concentrations are 1.6
mg/L (according to median of 359 wells). The three wells located within 1500 m of Ken
Lake showed an average Na concentration of 4.6 mg/L and an average K concentration of
2.5 mg/L. We sought to make determinations of the concentrations of these elements in
the lake water itself.


Materials and Methods
Sample Preparation

        Samples of lake water were taken from Ken Lake, Olympia, WA on 11/08/02
from the coordinates 47 01’ 59.1” N latitude, 122 57’ 04.6” W longitude. The samples
were taken from 0.5, 1.5, and 2.1 m depth and labeled A, B, and C, respectively. They
were contained in one-liter, Nalgene bottles for a few hours until filtered with a 0.45 μm
membrane filter with a vacuum filter apparatus. About 250 mL of the filtered samples
were placed into acid-washed 500 mL Nalgene bottles and treated with enough HNO3 to
lower the pH of the water to < 2.00. An additional 125 mL was put into clean Nalgene
bottles for ion chromatograph analysis. The rest of the samples were used for alkalinity
titrations. Samples were placed in refridgerator until analyzed.

        Stock solution of NaCl and KCl were prepared by the faculty:

Na Standard:             1000 μg/mL           1.2707 g NaCl / 500 mL

K Standard:              1002 μg/mL           1.9025 g KCl / 1000 mL

        The total concentration of Na in the solution is then 1g/mL (1 ppm). The total
concentration of K in the solution is then 2 g/mL (2 ppm). We also added 10.00 mL of a
Clemens                                  Ken Lake                                          5


CsCl solution at 10,000 ppm as a source of easily ionized electrons. The solution was
transferred to plastic bottles for use in the AA instrument.

        A medium standard was prepared with concentrations of 3 µg Na/mL and 6 µg
K/mL. This corresponds to 3 and 6 ppm.

        For the preparation of a blank, 10.00 mL of 10,000 ppm CsCl solution was diluted
to 100.00 mL.

        The full procedure for use of the AA instrument can be found on our website (see
bibliography for web address). The instrument parameters used during this analysis are
detailed in Table-4. The AA instrument was used for a total of 67 trials including our
blanks and instrument-drift checks. The standard methods handbook cites a linear
working range for concentrations of Na of up to 1 μg/mL and up to 2 μg/mL for K.
Blanks were run at the beginning, middle and end of our trials to correct for background
and drift check. The instrument showed little to no drift throughout the analysis.

        Regression analysis was used to determine the concentration of both Na and K.
Since both averages fell within the linear working range, this was a simple task and the
equation that we used was as follows:

                                          C = A/k

where C is the concentration of the sample, A is the measured absorbance and k is a
constant specific to the element. The constant, k was obtained through the regression
analysis. Its values are: for sodium, k = 0.1970; for potassium, k = 0.2235. Regression
analysis was carried out with Microsoft Excel, version 9.0.4402.

Table 1 Showing the parameters of the
Perkin Elmer atomic absoption
spectrometer

 Perkin Elmer Atomic Absorption
             Spectrometer
                       Na      K          Results
    Slit Width       0.7 nm 1.4 nm
   Wavelenth        589 nm 766.5 nm               We showed an average Na concentration
  Lamp Current       10 mA  12 mA         of 3.0 ppm (3.0 g/mL) and an average K
   Slit Setting         3      4
Wavelength Setting VIS-295 VIS-383        concentration of 1.2 ppm (1.2 g/mL) for our
Clemens                                    Ken Lake                                            6


samples. Sample A from 11/08/02 showed values of Na and K concentrations much
higher than the rest of the samples (greater than 2 standard deviation values form the
mean, and can be thrown out with greater than 90% confidence according to the
statistical Q-Test for bad data). Therefore, they were not considered in the final analysis
of data. Table 2 summarizes the results from our trials run on the atomic absorption
spectrometer.



Table 2 Results from our atomic absorption spectrometer analysis of Ken Lake water

                Potassium                                              Sodium
                              Absorbance                                               Absorbance
       mean K blank                0.008                   mean Na blank                    0.069
       mean K conc                 0.034                    mean Na conc                    0.127
        corrected                  0.026                      Corrected                     0.058


       mean low std                0.455                    mean low std                    0.265
   corrected low std               0.447                   corrected low std                0.197


   Regress Anal Info                                      Regress Anal Info
conc            abs                                conc            Abs
        0.000         0.000                                  0.000             0.000
        2.000         0.447                                  1.000             0.197


   Total avg K (ppm)                 1.2                  Total avg Na (ppm)                  3.0



Discussion
         The sample of water contained in sample bottle A showed unusual results in tests
for sodium and potassium during this trial. In addition to atomic absorption spectroscopy,
the ion chromatograph was used to analyze Ken Lake water for sulfates, among other
anions. Those results showed unusually high concentrations of sulfates in the water.
Additionally, the acetic acid method for determination of dissolved, reactive phosphporus
showed absorbance more than 2 times higher than absorbances in the other two lake
samples taken on the same day.
Clemens                               Ken Lake                                         7


References

Department of Ecology, “For Temporary Modification of the State
Surface Water
     Quality Standards for the Use of Pesticides to Control Aquatic
     Pests Plants and/or Algae in Ken Lake.” Administrative Order
     No. DE 01 WQSR-2468. July 2001. Document stating specific
     conditions for herbicides applied to Ken Lake, chemical requirements,
     general conditions, and public notices. Requested and received from
     Kelly Susewind, Southwest Region Manager, Water Quality Program,
     DOE.
Drost, B.W., Turney, G.L., Dion, N.P., and Jones, M.A. Hydrology and Quality of

      Ground Water in Northern Thurston County, Washington. Tacoma,

      Washington. 1998. Water-Resources Investigations Report 92-4109 (Revised).

      Describes groundwater system in Thurston County, WA, discusses chemical

      characteristics of water in aquifers and patterns of groundwater contamination and

      establishes guidelines for monitoring of groundwater levels and quality.

      Complete with charts and tables. From U.S. Department of the Interior and U.S.

      Geological Survey.

Lebow, Stan T., Lebow, Patricia K., Foster, Daniel O. “Environmental Impact of

      Preservative Treated Wood in a Wetland Boardwalk.” Forest Products

      Laboratory. February 2000. Discusses different chemicals used for wood

      treatments on hard to treat woods and how these treatments react in environments

      with heavy rainfall. Specific mentions of environmental concerns with treatments

      used in the North West, mostly copper, zinc, and arsenic metals leaching out.

      Authors consist of a Research Technologist, a Mathematical Statician, and

Lebow, Stan T., Halverson, Steven A., Morrell, Jeffrey J., and Simonsen, John.

      “Role of Construction Debris in Release of Copper, Chromium, and Arsenic
Clemens                                Ken Lake                                           8


      From Treated Wood Structures.” Forest Products Laboratory. June 2000.

      Provides information on different wood preservatives from treated woods in

      manufacturing. Includes leaching, chemical treatments, and different types of

      woods. Discusses the risks of chromated copper arsenate as wood treatment.

      Authors all work for Forest Products Laboratory, Madison, Wisconsin.

McCord, James T., Moore, Barry C., and Searcy, Chris C.
“Hydrological and
      Limnological Study of Ken Lake, Washington.” State of Washington

      Research Center. November 1989. Washington State University-Pullman.

      General report of formation and overview of Ken Lake system, i.e. phosphorous

      levels, topography, infiltration capacity, etc., and the Lakemoor community’s

      effects on the lake, including problems with runoff, storm water drainage, and

      sewer leakage. Most comprehensive report found on Ken Lake.

Online: <http://www.speclab.com/compound/. (Accessed 11/13/02). CAS # 145733

      and CAS # 1071836. Gives comprehensive information on chemicals, including

      EPA methods for chemical applications, melting points and decomposition,

      sensitivity data, and environmental impact. Analytical chemistry web site,

      nationally known.

Standard Methods Handbook for the Atomic Absorption Spectrometer. Located at

      The Evergreen State College, Lab 1, 2nd floor, in the Environmental Lab.

      Commonly referred to as the “Bible,” the handbook gives specifics for

      wavelength settings for different cathode lamps, flame settings, slit widths, and

      many other useful pieces of information on properly operating the Atomic

      Absorption Spectrometer for different elements.
Clemens                                 Ken Lake                                         9


Stroh, J. http://academic.evergreen.edu/curricular/envana2002/2002-

       2003/handouts/AA%20labs/AAFLAME-02.doc “Operating Instructions for the

       Atomic Absorption Flame Unit.” 1988 (modified 1999). Instructional paper

       provided by The Evergreen State College. Provides information on proper

       operation of the Atomic Absorption Spectrometer. Author is currently a Professor

       of Geology/Hydrology at The Evergreen State College in Olympia, Washington

       and is also currently undergoing an in-depth research project in the Saline Valley,

       California.

				
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