FY 1983

Distribution of hydrocarbons and microbial populations related to sedimentation processes in lower Cook Inlet and Norton Sound, Alaska

Atlas, R.M., M.I. Venkatesan, I.R. Kaplan, R.A. Feely, R.P. Griffiths, and R.Y. Morita

Arctic, 36(3), 251–261, doi: 10.14430/arctic2274 (1983)

In spring and summer 1978 and spring 1979 an integrated study was carried out to examine the interrelationships of physical (sediment deposition), chemical (organic carbon and hydrocarbon concentrations), and biological (microbial populations and activities) factors in the Cook Inlet and Norton Sound regions with respect to the probable sinks and fates of hydrocarbon contaminants within these ecosystems. Most of the fine-grained sediment entering Cook Inlet is transported out of the inlet into Shelikof Strait; however, significant sediment accumulation occurs within areas of Kamishak and Kachemak bays. In Norton Sound, sediment from the Yukon River is transported counterclockwise around the embayment and approximately 50% is deposited in the nearshore regions of the sound. In both regions, areas of high sediment accumulation are richer in organic carbon and hydrocarbon derived from land than areas of low sediment accumulation. In general, areas with high sediment accumulation rates for fine-grained particles are also areas of relatively high microbial activity. Results suggest that these elevated microbial activities reflect biodegradation of detrital carbon associated with these particles. Also, the Cook Inlet and Norton Sound region were found to be free from petroleum hydrocarbon contamination (with the exception of one area in Cook Inlet). No evidence was found of hydrocarbon accumulation resulting from a gas seepage in Norton Sound, nor for accumulation of hydrocarbons in sediments of lower Cook Inlet and Shelikof Strait from oil well operations in upper Cook Inlet.