Agriculture Reference
In-Depth Information
The influence of groundwater inputs on nutrient availability differs between
lakes and wetlands in southern Michigan, as can be seen in Fig. 11.12, although
the sample set given is biased by the prevalence of groundwater-fed lakes in
the area (i.e., those with Mg
2+
concentrations exceeding about 1.0 meq L
−1
).
Both TDP and NO
3
−
are often, but not always, higher in groundwater-fed lakes
(Fig. 11.12). Wetlands, especially those fed by precipitation (as indicated by Mg
2+
< 1 meq L
−1
), often have TDP concentrations that are high by lake standards, for
reasons that are not well understood. In contrast, NO
3
−
concentrations tend to be
lower in wetlands even where groundwater with high NO
3
−
concentrations is an
important water source, likely reflecting the high capacity of wetlands for both
Table 11.3. Hydrochemistry of surface waters in the vicinity of Kellogg Biological
Station.
Measurement
*
Surface waters
Augusta
Creek
a
Gull
Lake
b
Wintergreen
Lake
c
Lawrence
Lake
d
Lower
Crooked Lake
e
# of dates
34
42
16
7
18
Conductance
(μS cm
−1
; 25
o
C)
481
348
343
441
205
pH
8.06
8.12
8.09
7.94
8.53
ANC
*
(mg HCO
3
−
L
−1
)
286
189
182
266
100
Ca
2+
(mg L
−1
)
70.6
36.8
38.9
63.0
21.0
Mg
2+
(mg L
−1
)
21.3
21.7
18.6
22.7
9.33
Na
+
(mg L
−1
)
6.45
6.30
6.54
5.54
6.98
K
+
(mg L
−1
)
1.21
1.24
6.10
2.43
0.47
Cl
−
(mg L
−1
)
11.1
11.8
14.2
6.40
17.6
SO
4
2−
(mg L
−1
)
19.8
23.3
8.74
18.1
4.16
NO
3
−
(mg N L
−1
)
1.10
0.20
0.06
0.62
0.02
NH
4
+
(mg N L
−1
)
0.019
0.090
0.150
0.183
0.014
Si (mg Si L
−1
)
5.55
3.37
0.84
5.91
0.14
DOC
*
(mg L
−1
)
4.92
5.65
11.44
4.30
9.24
TDN
*
(mg L
−1
)
NA
NA
NA
NA
NA
TDP
*
(mg L
−1
)
0.008
0.007
0.049
0.009
0.007
*
DOC = dissolved organic carbon, ANC = acid-neutralizing capacity (also known as total alkalinity), TDN = total
dissolved N, TDP = total dissolved P.
a
Augusta Creek was sampled near its mouth at the Village of Augusta; Hamilton lab database queried December 2009.
b
Gull Lake data are means of integrated samples of the epilimnion and point samples from the middle of the
hypolimnion (Raikow et al. 2004); Hamilton lab database queried December 2009.
c
Wintergreen Lake data are means of samples taken mostly at its outflow stream, representing the epilimnion when it
was stratified; Hamilton lab database queried December 2009.
d
Lawrence Lake data are means of samples taken at several depths when it was stratified; Hamilton lab database
queried December 2009.
e
Lower Crooked Lake data are means of samples taken near the surface, mostly in May and October when it was not
stratified; Hamilton lab database queried December 2009.
