Activity of bacteria in the liberation of phosphate from the sea sediments in bottom water
Abstract
1) In the experiments we observed the fluctuation in the number of heterotrophic bacteria, free phosphate, the quantity of oxygen and H-ion concentration, and the obtained results are discussed.
2) It has been ascertained that under controlled laboratorial conditions, sea water in contact with sea mud, dissolves chemically from the latter determined quantities of free phosphate. The quantity of chemically dissolved phosphate from certain quantities of mud, are in the reversed proportion with the quantity of disponible mud. So from 10 gr. of mud are chemically dissolved in 300 cm3 of water about 33,6 mgr/m3. The dissolved quantities of phosphate remained in the solution for 13 days and at the close of the experiment they were in a slight decrease.
3) From the natural sea mud are liberated within 12 days in the conditions of the experiment, in natural sea water bigger quantities of free phosphate under strictly anaerobic (93,0 mgr/m3) than under aerobic (69,0 mgr/m3) or semi-aerobic conditions (81,5 mgr/m3). The liberated quantities of phosphate were in constant rise during 12 days, as long as the experiment lasted.
4) The suspension of various bacterial species liberates after 17 days from sterile mud and sterile sea water bigger quantities of phosphate under strictly anaerobic (70,5 mgr/m3) than under aerobic (30,0 mgr/m3) or semi-aerobic conditions (40,5 mgr/m3).
The total amount of liberated phosphate is less than the one liberated from the natural mund and sea water. Also under these conditions the dissolved phosphate was substantially in constant increase during the 17 days of the experiment.
5) Pure bacterial cultures liberate from the mud, under determined conditions on average about 10,4 mgr/m3 of phosphate in 24 hours and the quantitiy of liberated phosphate in the single cultures varies greatly.
