Organic matter accumulation in sediments of hypersaline Mono Lake during a period of changing salinity

Abstract

Finely laminated sediments of Mono Lake provide a detailed paleolimnological record of organic matter accumulation during a period of large fluctuations in salinity that resulted from climatic variation and water diversions. In sedimentary profiles representing the last 170 yr, organic carbon content of the sediments varied from 6.6 to 16.1%. The accumulation rate of organic carbon at a sedimentation rate of 0.7 cm yr−11 varied from 76 to 164 g C m−2 yr−1. The most notable change was a gradual increase in 5‐yr mean accumulation rate from 87 to 153 g C m−2 yr−1 as salinity increased from ~48 to 97 g liter−1 during the recent period of water diversions (1941–1982). Although the correlation between organic matter accumulation and salinity during the recent period may be due in part to the slow decay of organic matter under hypersaline conditions, a positive correlation between accumulation rates and estimated lake salinities at time of burial exists throughout the 170‐yr record.