NEW: Annual Report - George Mason University

74
Total Alkalinity (mg/L CaCO3), GMU
100
90
80
70
60
50
40
30
Station 7: June-Sept
20
1980 1985 1990 1995 2000 2005
YEAR
Total alkalinity as measured
by GMU personnel has shown
a trend line increase from
about 55 mg/L as CaCO3 in
1984 to about 65 mg/L in
1991 followed by a graduate
decline which reached about
60 mg/L in 2003 (Figure 86).
A linear regression over the
whole study period was not
significant (Table 10).
Figure 86. Long term trend in Total Alkalinity (GMU Lab Data). Station 7. Gunston
Cove.
Total Alkalinity (mg/L CaCO3), GMU
110
100
90
80
70
60
50
Station 9: June-Sept
40
1980 1985 1990 1995 2000 2005
YEAR
Total alkalinity in the river as
measured by GMU personnel
has covered a fairly broad
range each year (Figure 87).
The trend line was fairly
constant from 1984 to 1990 at
about 65 mg/L as CaCO3, rose
to about 75 mg/L in 1995 and
has declined in recent years to
about 65 mg/L in 2003. A
significant increase in
alkalinity was suggested by
linear regression analysis at a
rate of 0.38 mg/L per year
(Table 10).
Figure 87. term trend in Total Alkalinity (GMU Lab Data). Station 9. River mainstem.