Geology Reference
In-Depth Information
FIGURE 15.8 Trace element concentrations (ppm) in aquatic vegetation along Bee Fork and tributary. New Lead Belt (Gale et al., 1973).
8.
The pollution load that a stream carries can be calculated if
the stream discharge and the concentration of the specific
contaminants are known.
Concern about potential degradation of water quality
and aquatic biota of nearby federally protected streams
prompted a multidisciplinary study of the area that began in
2000. The results of the sediment and surface water analyses
on samples collected between 2002 and 2005 have been pub-
lished by the USGS (Brumbaugh et al., 2007). That publica-
tion is the source of much of the following environmental
information.
The greatest concentrations in sediment collected in
2002 were from sites downstream from mines on Strother
Creek and West Fork, with noticeable enrichment in lead in
sediments from Bee Fork. Compared to reference sites, sedi-
ments downstream from mine areas were enriched "by fac-
tors as large as 75 for cadmium, 62 for cobalt, 171 for nickel,
95 for lead, and 150 for zinc."
The impact of mining was recorded at least 75 kilome-
ters downstream in Clearwater Lake where metal concentra-
tions were 1.5-2.1 times greater than in sediments in an area
of the lake with no upstream mining. Sediment samples col-
lected in 2004 on West Fork showed "dramatically lower"
concentrations of metals, which was attributed to the closing
of a mill on West Fork.
Concentrations of metals in surface water generally
tracked those in sediments. Water samples from July 2005 on
Strother Creek showed a "considerable increase in metal
loadings" for a few days in which there was a moderate
increase in stream discharge.
Load (tons/day) = Q X C X 0.0027
where Q = stream discharge (cfs), C = concentration of
specific contaminant (mg/L), and 0.0027 = constant to
convert seconds and mg/L to days and tons
Using the available data and the formula given above,
calculate how many pounds per day of lead and manganese
were being transported past site 7 (Figure 15.7; refer to
Appendix A for conversion of tons to pounds).
9.
What techniques might be used to reduce the contamina-
tion of these streams in the New Lead Belt?
10.
Using the above information from the USGS studies that
began in 2000, briefly describe, in a bullet statement for each,
the key findings or conclusions that you might make from
this study of part of the New Lead Belt.
