Sediment Oxygen Uptake in South Swedish Lakes

Abstract

Oxygen uptake was measured over sediment cores collected during one year in five lakes of different trophic status in South Sweden. Oxygen availability and temperature seemed to regulate seasonal variations in sediment oxygen uptake. Q10 values for sediment oxygen uptake were 2.0-3.0 for the interval 5-100C and 1.3-1.6 for the interval 15-20'C. The oxygen uptake of undisturbed sediment cores sampled in late autumn and of sieved and restratified sediment was studied at temperatures from 5 to 20'C. At the same temperatures, these samples had an oxygen uptake similar to that of samples taken monthly during the year and incubated at the in situ temperature, indicating a strong buffering capacity for sediment respiration. Freshly-sedimented organic material seemed to be of minor importance in determining the seasonal changes in sediment oxygen uptake. Although annual pelagic primary production was different for the five lakes (20-575 g C m-2 yr-1), annual oxygen uptake of the sediments showed a much more restricted range (94-235 1 02 m' yr ).