『Abstract
The quality, quantity, and origin of suspended organic matter
were studied in the highly agricultural Upper Scioto River in
Central Ohio. Late summer baseflow conditions were compared to
late autumn high flow conditions. Variables examined in the suspended
matter were the total suspended solids concentration, semi-quantitative
concentrations of lignin, carbohydrate concentrations, total organic
C, total and organic P, and δ-13C. Also examined were
ratios of C to N, organic C to organic P ratios and fluxes of
total organic C. The primary hypothesis of this research was that
the quality (or biodegradability) and quantity of organic matter
in the Upper Scioto River would increase during autumn stormflow
conditions due to inputs of fresh terrestrial organic matter.
The autumn suspended matter was also expected to reflect C4 plant
contributions from corn organic matter. Results show that the
quality and quantity of organic matter were greater during summer,
as reflected in low molar ratios (178:1) of organic C to organic
P, and higher organic C content of the suspended matter in summer.
Summer suspended matter was 3.6％ organic C and autumn suspended
matter was 2.3％ organic C. Carbon to N molar ratios in both seasons
were very close to the Redfield ratio (6.6:1 in summer and 6.7:1
in autumn). Total suspended matter and total organic C concentrations
were lower in autumn (8.7 mg/l-1 TOC and 17.7 mg/l-1
TSS) than in summer (17.5 mg/l-1 TOC and 39.0 mg/l-1
TSS), but the fluxes were greater in autumn due to greater stream
flow. Stable isotope analyses suggested a phytoplankton or C3
plant source (most likely corn) for summer organic C (mean δ13C
of −24.8‰) and a phytoplankton or C4 plant source for autumn organic
matter (δ13C＝−21.5‰).』
1. Introduction
1.1. Background
1.2. Objectives
2. Physical setting
3. Methods
3.1. Sampling
3.2. Analytical
4. Results
4.1. Hydrology
4.2. TSS,TOC, and TOC loading
4.3. Dissolved N and P
4.4. C:N and OC:OP ratios
4.5. Lignin and δ-13C
5. Discussion
5.1. TSS, POC, and TOC loading
5.2. N and P dissolved species
5.3. C:N, OC:OP and TP loading
5.4. Lignin
5.5. δ-13C
6. Conclusions
Acknowledgements
References