Denitrification - Study Area
The Sugar Creek and Iroquois River watersheds are located in the Upper Illinois River basin, and their drainage areas are 422 and 1553 km2, respectively. Both watersheds are heavily impacted by agriculture; more than 90% of each drainage basin is devoted to farming. A major unanswered question regarding nitrogen delivery to coastal waters is the net effect of in-stream processes on nitrogen transport in small and medium sized rivers. Current thinking suggests that nitrogen-cycling processes (such as denitrification) should have the greatest impact in small rivers due to greater contact between river water and bed and bank sediments.
Iroquois River and Sugar Creek watersheds. Highlighted on the map are the sampled reaches of each river. The Iroquois reach was 13 miles long; the Sugar Creek reach 24 miles long.
The rivers differ in both their physical and biological characteristics, as shown below.
| Sugar Creek | Iroquois
River |
|||
| WATER
COLUMN |
1999 |
2000 |
1999 |
2000 |
|
Discharge (cms) |
0.02
- 0.17 |
0.38
- 2.06 |
0.54
- 0.64 |
5.74
- 19.8 |
|
Chlorophyll |
3.4
+/- 1.1 |
4.8
+/- 0.5 |
6.0
+/- 1.7 |
5.3
+/- 0.6 |
|
Bacterial # (10XE6/mL) |
1.89
+/- 0.58 |
2.22
+/- 1.11 |
1.08
+/- 0.59 |
2.92
+/- 0.28 |
|
Nitrate (umol N /L) |
10.7
- 70.7 |
650
- 786 |
33.6
- 51.4 |
526
- 1021 |
| SEDIMENT |
||||
|
Grain Size (mm) |
1.4 +/- 0.9 | 0.19
+/- 0.05 |
||
|
% C |
0.1
- 6.6 |
0.7
- 6 |
||
|
%N |
0.11
- 0.44 |
0.0002
- 0.36 |
||
