Geology Reference
In-Depth Information
Exercise 15 • Groundwater and Surface Water Contamination from Resource Extraction
235
Changes in water quality and aquatic life in these
streams since 1955 are related to the discharge of
milling and mining wastes which include excess water
pumped from mines, finely crushed rock, chemical
reagents, and waste oils and fuel. These wastes are
allowed to settle in holding ponds, and the effluent is
either reused or allowed to discharge into streams. The
greatest share of the noxious substances is retained in
the settling basins.
Most of the heavy metals in the streams are in
very fine particles; a minute amount is dissolved but
most heavy metals travel on suspended sediment in
the water. Where large excesses of groundwater have
been pumped from mines and discharged into streams,
significant algal blooms have occurred. They may be a
result of the nutrients in the groundwater. The dense
algal communities act as filters and remove many of
the fine particles that escape the settling basins.
In this exercise we begin by investigating metal
contamination of water and aquatic organisms on the
West Fork Black River and tributaries Strother Creek,
Neal Creek, and Bee Fork Creek (Figure 15.7) using
data published in 1973 (Gale et al., 1973). We conclude
with an assessment of conditions in this same area
based on sampling of water and sediments between
2002 and 2005 (Brumbaugh et al., 2007).
QUESTIONS 15, PART C
1.
Examine Figure 15.7 and Table 15.3. Sample sites 6, 9, 10,
and 14 are in uncontaminated areas. What are the back-
ground concentrations of the following elements in surface
water?
Lead:
Zinc:
Copper:
Manganese:
2.
In Figure 15.7 mark in red (or use a pattern [e.g., dots] that
you identify in the explanation) the stream reaches that
exceed background concentrations of lead. Consider the
most likely source of the lead as a guide in marking the
stream reaches.
5.
On the basis of available data, would you expect back-
ground concentrations of the contamination in Creek A?
Explain.
3.
In Figure 15.7 mark in green (or with a dash pattern) the
stream reaches that exceed 0.011 ppm of zinc.
6.
Examine the Mn concentrations in aquatic organisms in
4.
What relationship appears to exist between settling basin
Strother Creek as shown in Table 15.4.
location and the quality of water in the stream?
a.
What general relationship is evident?
