Seasonal Dynamics of Inorganic Nutrients in the Plum Creek Tributary of
the Black River in NE Ohio as a Function of Land Use Practices
Mercedes Allen, Ryan King, Garrison Loope, & Cheryl Wolfe-Cragin
Oberlin College, Systems Ecology 316, Fall 2007
Urban
Residential
Forested Park
Golf course
Agriculture
2
3
4
1
Water samples were collected weekly from the four
sites during spring, summer, and fall of 2007 and
averaged monthly. Samples were analyzed for NO3
and PO4 concentrations using an ion chromatograph.1
Precipitation data was collected from the AJ Lewis
Center Data Monitoring System gauge on the roof of
the AJLC.
Findings
3.5
NO3 Concentration (mg/l)
Land use activities within a watershed have an
important influence on stream water quality and
can affect both spatial patterns and temporal
patterns. Plum Creek is an area of transition from
highly agricultural areas found upstream to the
urban/suburban portions of Lorain County.
Understanding of the impacts of nonpoint
pollution, especially seasonal variation, is crucial
in order to identify and implement best
management practices (BMPs) in the agricultural
community and effective zoning practices by local
officials. Our objective was to compare the water
quality at four Plum Creek sites in different
seasons to determine seasonal variability in
nutrient levels. Each site is directly downstream
from a different land use:
2
4
Analogous studies of NE Ohio agricultural ecosystems
have found that nitrogen levels are low in the summer,
while nitrogen levels are high in winter due to high flow
and loading combined with low removal rates.3
We expected elevated nutrient levels in the spring due
to runoff from spring planting in upstream agricultural
fields and during the fall due to application of manure
and fall plowing. Also, based on previous studies we
expected the City of Oberlin to dilute inorganic
nutrients downstream.2
3
2
1
0
March
April
May
June
July August
Oct.
Nov.
3.0
2.5
2.0
Site
Site
Site
Site
•NO3 and PO4 data did not correlate with precipitation
information. No relationship was found between precipitation
and nutrient concentrations in the creek.
1
2
3
4
•Standard deviation within months shown by error bars is
indicative of large variability within seasons.
1.5
1.0
0.0
Conclusions
March
April
May
June
July
Month
August
Oct.
Nov.
•No nutrient peak corresponding to spring planting and fertilization is found.
•NO3 and PO4 are greatest in August-November at all four sites. Site #4
representing agricultural inputs has the highest NO3 during this period while
Site #1 representing the urban/residential inputs is lowest. This suggests
that high nutrient runoff from agricultural fields upstream is diluted by
urban/suburban runoff as it moves downstream.
PO4 Concentration (mg/l)
3
Average Monthly Nitrogen Concentration
Monthly Averaged Precipitation for 5day Periods Prior to Sampling
0.5
Flow
1
5-day precipitation (in)
Methods
Background and Objectives
•Plum Creek has seasonal variation in nutrient concentrations
between March-July and August-November.
•This large change may be associated with application of manure
and tilling of agricultural fields. These land use practices upstream
may affect downstream inorganic concentrations.
•Management officials should consider reducing the application of
fertilizers on agricultural fields in the fall. This will result in lower
levels of inorganic nutrients in the Black River and Lake Erie.
Average Monthly Phosphorous Concentration
•Research should be continued for multiple years and include
December-February samples in order to gain confidence in the
data and determine potential changes in BMPs.
0.35
0.30
0.25
Site
Site
Site
Site
1
2
3
4
0.20
References
0.15
0.10
1Clesceri,
S. Lenore. Standard Methods for the Examination
of Water and Wastewater, 17th edition, 1989.
0.05
0.0
2Feeser
March
April
May
June
July
Month
August Oct.
Nov.
et al. Oberlin College, 2006
3Birgand,
F. Nitrogen Removal in Streams of Agricultural
Catchments, 2007.