Moeller, John R.; Minshall, G. Wayne; Cummins, Kenneth W.; Petersen, Robert C.; Cushing, C. E.; Sedell, James R.; Larsen, R. A.; Vannote, Robin L. 1979. Transport of dissolved organic carbon in streams of differing physiographic characteristics. Organic Geochemistry. 1(1): 139-150.
Transport of dissolved organic carbon (DOC) in four river systems in different physiographicregions of the United States was related to link magnitude by a power function, log Y = -0.84 + 1.24log X. Multiple linear regression indicated that discharge, watershed area, and link magnitude explainedalmost all variation in DOC transport. For purposes of ecosystem comparison, link magnitude appearedsuperior to other classification systems, such as stream order.
In two of the river systems, the largest fraction of DOC was transported in the spring. A thirdhad a winter transport maximum; the last had bimodal spring and fall maxima.
Streams transporting similar total amounts of DOC may vary widely in DOC concentration (mg.1- ').Particulate organic matter concentration was not simply related to that of DOC.
Ranges and means of DOC concentration, mean DOC:POC ratios, annual load of transportedDOC as well as annual watershed DOC output were tabulated for 45 streams and rivers, representinga broad range of stream systems and physiographic regions. Mean DOC concentration for these 45waterways ranged from 0.7 to 28 mg .1-1. The very low DOC values are found in undisturbed streams;many of the higher values are associated with larger streams influenced by human activities. MostDOC outputs fell within the range 0.21-5.42 metric tons. km-2. yr -1; mean DOC:POC ranged between0.09 and 70.
A comparison was made among several biomes of the ratio of exported DOC to watershed grossand net primary production. DOC, while playing a major role in aquatic ecosystem organic budgets,appears to be of little significance in the nutrient balance of watersheds.