Experiments with Pond Muds

Publisher Website
Google Scholar
Abstract
At the mud surface, in ponds, 2 series of reactions are in progress: the decomposition of organic matter resulting in the liberation of NH4NO3, and the adsorption of NH3 by the mud with the liberation of exchangeable bases. The balance between these 2 sets of reactions together with the temp. and amt. of available O2 provide the environment in which algal resting-spores live and may affect their germination. Mud of 3 types, a peaty unsaturated mud, a neutral organic mud and a highly calcareous mud, was kept in large jars covered with 1% l. of pond water and samples of water were analyzed at 2-week intervals. Inorganic N was seriously depleted in the first month in saturated muds; in all cases the initial nitrate had almost disappeared after 2 weeks. The carbonate hardness, pH and Fe content varied with the extent to which NH3 was available to replace the respective cations. Growth of algae was greatest after 6 weeks when inorganic N was very low. The presence of leaf mould in some cases brought about continued production of NH3, increased phosphate and, in unsaturated mud, greatly increased Fe.