Nutrient Chemistry of Chukchi Sea Sediments

The Chukchi Sea is a relatively shallow marginal sea of the Arctic Ocean. It has an extensive continental shelf and is a moderately high productivity ecosystem. Climate warming is occurring in the southern section of the Chukchi and as such changes in nutrient concentrations may be occurring. Surface sediment samples were collected throughout the Chukchi in 2004. The clay fraction was isolated and concentrations of inorganic and organic phosphate were measured. The distribution of organic phosphate within the Chukchi shows enrichments to the south where nutrient-rich waters feed into the Sea. Inorganic phosphate concentrations are highest in regions where freshwater inputs occur, particularly along the Alaskan coast. Concentrations of inorganic and organic phosphate were also measured in the whole sediment and sand and silt sized fractions. Organic phosphate concentrations were highest in the clay fraction as expected. Phosphate concentrations were also compared to concentrations of total C, N and S. Overall nutrient concentrations in the sediments is highest closer to the Bering Strait however anomalous concentrations of N and S were noted in several samples collected to the north along the Russian coast.