FLOOD10381

• County: Pueblo
• Stream Name: Arkansas River
• Basin: Arkansas
• Title: Effects of Impoundment on Water and Sediment in the Arkansas River at Pueblo Reservoir
• Date: 5/1/1977
• Floodplain - Doc Type: Educational/Technical/Reference Information

2 or 3 days of collection. These procedures were fol-
lowed to minimize losses of the metal ions to the con-
tainer walls or volatilization to the atmosphere as in
the case of mercury. This procedure obviated the neces-
sity of adding HN03 or other preservatives and con-
sequently eliminated the introduction of foreign sub-
stances with the potential of introducing major sources
of contamination,

Table 1 lists the parameters analyzed by chemical and
physical methods. These are, for the most part, typical
parameters measured in limnological studies, Therefore,
the parameters in table 1 will be referred to as the
"gross limnological parameters" throughout this report.
Figure 3 gives the observed correlation between TDS
(total dissolved solids) and conductivity in Pueblo
Reservoir. The results are fully consistent with the work
reported by Hem [3] within the range measured.

700

..

600

..

~oo

.

400

200

,

.

100

o

100

200 500 400
T, 0, S,(mg/l>

~oo

Figure 3,-Relationship between total dissolved solids and spe-
cific conductance in Pueblo Reservoir.

Table 2 gives the methods used for the analysis of the
trace metals. These include: flame atomic absorption
spectrophotometry analysis with direct aspiration of
the sample (AA-Direct Asp.). flame atomic absorption
analysis after preconcentration of the sample by the
ammonium pyrolidine dithiocarbamate-methyl isobutyl
ketone extraction technique [1,2] (AA-APDC-MIBK-
Extr.) and flame photometry (FP-Direct Asp.). Arsenic

was analyzed using the silv r diethyldithiocarbamate
spectrophotometric method [4] after concentrating
samples by evaporation fro 300 ml to 25 to 50 Jl11.
Mercury was analyzed using th flame less atomic absorp-
tion cold vapor technique usi g 100-mg samples [5].

In table 2 the detection lim ts for the spectrophoto-
metric or photometric determi ations are equal to twice
the normal peak-to-peak nois , In some cases the detec-
tion limit observed for some arameters is not as low as
might be expected because f unusually large or in-
consistent reagent blank sign Is encountered. This was
a particular problem with sus ended and sediment sam-
ples analyzed for Ca, Mg, and Na, for which there were
large reagent blank signals.

,

Sediments were also analyzd for some metals using
X-ray fluorescence spectrosco' y. Table 3 lists the metals
analyzed by X-ray fluoresce ce and the approximate
detection limits obtained in t ese experiments.

Table 3.- X-ray f1uores ence parameters
and detectio limits

f/)
:z.
...

Trace Metal

Fe
Mn
Mo
Zn

>-
~
>
~
U
::l
Q
Z
o
u

Data

Detection Limits (mg/g)

50 (0,005 percent)
20 (0.002 percent)
50 (0.005 percent)
10 (0.010 percent)

The data obtained in the present study are tabu-
lated in appendices A and . Appendix C presents
the data for the dissolved fr ction obtained from the
pre-impoundment study of. the river at locations
which subsequently were desi nated outlet site Hand
reservoir E, respectively. Ap endix D lists the dis-
charge data for the Arkansas iver near Portland [6],
covering the impoundment st dy period.2 Appendix A
presents the data from the di. solved sample fractions;
data from the suspended frac ions appear in appendix
B, The tables in appendices and B list the data by
parameter, sampling date, sa piing site (A, B, C, D,
etc.). and depth (surface, 3 m tres, 5 metres, etc,) for
each sampling year (June 197 to May 1975, and June
1975 to March 1976), Asteris s indicate that either no
analysis was performed for th t parameter on a sample
collected or that no sample w s collected at all at that
site on the date indicated. ny value listed as zero
should be interpreted as m ning "not detectable."
Detectable limits for various pararneters are given in

~

2 Colorado State Division of ater Resources, personal
communication.

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