COMPARING STORED ORGANIC CARBON IN FIRST AND SECOND ORDER STREAMS IN OTTAWA COUNTY, MICHIGAN

The goal of this study is to determine and compare amounts of stored organic carbon in first and second order alluvial streams in Ottawa County, Michigan. Land use change, fires, logging and agriculture, impact the amount of stored organic carbon in stream sediments and ultimately in our atmosphere. We hypothesize that stream order could affect organic carbon storage in small streams. Stored organic carbon percentages were determined using the loss on ignition method. Over 200 alluvial sediment samples in 18 different locations were analyzed for organic carbon content. Roughly the same number of samples were taken from each stream order. All the samples were collected approximately equidistant from one another, beginning at the head of the stream and continuing to the mouth. In first order streams, the mean percent organic carbon is 3.8 ± 2.3 (one standard deviation). In second order streams, the mean percent of organic carbon is 4.3 ± 2.2. While there is little difference in mean organic carbon content between first and second order streams, a closer examination of the data suggests that second order stream sediment is skewed towards the high end range of organic carbon content in the samples we analyzed. One sample site located near the Grand River (a much higher order stream) had some of the highest organic carbon contents measured.

These preliminary data suggest that higher order streams could have a greater capacity to store organic carbon than do lower order streams. In future studies we will examine larger streams in order to further test this hypothesis. Grain size, stream gradient, oxidation-reduction processes and many other factors could both explain and complicate the relationship between percent stored organic carbon and stream order.