Document Type


Publication Date

January 1981


The potential influence of periphyton photosynthesis on calcium carbonate precipitation was studied for the Logan River, Bear River Mountains, northern Utah. The water chemistry, hydrology, and benthic primary production of the river were monitored for one year. periphyton photosynthesis and calcium carbonate precipitation were measured concurrently in laboratory experiments utilizing radioisotopic tracers. These experiments investigated the effects of water temperature, velocity, and macronutrient concentration on photosynthetically induced calcium carbonate precipitation. In these experiments, the biologic induction of calcium carbonate precipitation was not correlated with water nutrient level. It did, however, reflect water temperature, and was greatest at approximately 10 degrees C. Furthermore, benthic calcium carbonate precipitation decreased nearly uniformly as water velocity increased. Application of the experimental results to the Logan River system suggests that biological activity would have the greatest influence in the high-altitude, first and second-order tributaries to the river, and would decline in importance in the downstream direction. Biological activity may account for up to 25 percent of the precipitation of calcium carbonate in the Logan River during certain times of the year.