Role of calcium carbonate precipitation in lake metabolism

Abstract

During a two year period analyses were made every other week on seston collected at three depths in a small hard-water lake in southwestern Michigan. The seston was analyzed for total dry weight, organic material, calcium carbonate, and ash content. During the second year seasonal changes in sestonic particulate organic carbon, Kjeldahl nitrogen, and total phosphorus were assayed.Organic material and ash content of the seston was similar both years, but the calcium carbonate content was five times greater in the second year than in the first. The dissimilarity in calcium carbonate precipitation between the two years was related to degree of vernal circulation and calcium ion concentration in the water column when the ice broke up. During the study an improved sediment trap was designed and constructed. The trap had replicated, discrete upper and lower sections, which permitted correction for attached and non-sedimenting matter.Investigation of calcium ion concentration by flame atomic absorption and a calcium ion electrode revealed an average of 36.7 mg l" 1 of colloidal calcium was suspended in the lake during 1973.Immumz a. w: VMS DOCUMENT !S OPOraiTEB Dr. Ellis willingly gave constructive advice and help in the x-ray diffraction analyses, thermal analysis, surface area determinations, and calcium electrode determinations.