RELATIONSHIP BETWEEN P-CO2 AND DISSOLVED ORGANIC-CARBON IN NORTHERN WISCONSIN LAKES

We investigated un relationships between early summer partial pressure s of CO2 (P-CO2) and dissolved organic carbon (DOC) concentration in t he surface waters of 27 northern Wisconsin lakes. other variables we c onsidered were die drainage ratio, lake area, lake depth and the exten t of wetland in each drainage basin. P-CO2, had a strong positive rela tionship with MW: concentration. There was a weak negative relationshi p between P-CO2, and lake area, which was most apparent In lakes with DOC concentrations: above 5 mg L(-1). DOC concentration was positively correlated with the drainage ratio and wetland extent. We conclude th at allochthonous C supplied by the drainage basin, particularly from a reas of wetland, is a major factor determining CO2 saturation of these lakes and suggest that there are two complementary mechanisms by whic h this can occur. Higher P-CO2, may result from higher in-lake respira tion of the allochthonous organic carbon, and/or from inputs of surfac e waters from wetlands that are high in both WC and CO2.