@ 1980, by the American Society of Limnology and Oceanography, Inc. Patterns of dissolved organic carbon in transport1

Two distinct patterns of dissolved organic carbon (DOC) in transport were observed in a southeastern Pennsylvania Piedmont drainage basin under low flow conditions. In relatively undisturbed woodland spring seeps, DOC concentrations increased with distance from the groundwater s,ources as did the apparent percentage of high molecular weight DOC. Changes in pH, color, and phenolic-C paralleled those for total DOC in a seep, while the concentration of carbohydrate-C remained relatively constant. In headwater areas perturbed by humans, cattle, or waterfowl, elevated DOC concentrations decreased rapidly from point source inputs. Dissolved organic matter (DOM), fre-quently measured as dissolved organic carbon (DOC), is an important compo-nent of the organic energy budget of tem-perate stream ecosystems (Fisher and Li-kens 1973; Fisher 1977) and often is the dominant form of carbon in transpor