Biological Productivity of Modern Aquatic Environments

Abstract

The biological productivity of aquatic environments, especially marine environments, is of great importance to the formation of potential oil source rocks. Although the primary productivity of organic matter in aquatic environments is presently in the same range as in subaerial environments — due to the wide-spread occurrence of land plants — the chance for preservation of organic matter in sub-aquatic environments is far greater. In sub-aerial environments, free access of air, together with the presence of moisture, allows growth and action of bacteria, and hence a breakdown and destruction of organic matter. However, in sub-aquatic environments, the deposition of fine-grained sediments limits access of dissolved molecular oxygen. Thus, the activity of aerobic bacteria comes to a halt when the limited amount of oxygen trapped in the sediments is exhausted. In this connection, it is also important to realize that air contains 21% (vol) of oxygen, whereas water normally contains only a few ml of oxygen per 1. Therefore, in practical sense, organic matter is only preserved and fossilized in sub-aquatic sediments.