Transport of copper from the Bering Sea to the northwestern North Pacific

Abstract

Dissolved copper concentrations in surface waters of the Bering Sea ranged from 106 to 882 ngl−1. Higher concentrations were found in continental shelf waters. In the northwestern North Pacific dissolved copper ranged from 54 to 140 ngl−1. Particulate copper concentrations varied regionally and seasonally from 6 to 79 ngl−1. Regionally averaged particulate copper concentrations decreased from 175 to 33Μg g−1 against an increase in suspended materials because of the dilution effects of biological fractions. Apparent sporadic increases in copper concentrations were found in the mixing area of the Kuroshio and the Oyashio waters. The feature is attributed to the lateral distribution of different water types rather than to the upwelling of deeper waters by eddies. In the same area west of 160‡E, waters with high concentrations of dissolved copper (96±9 ngl−1) were found. Their origin appears to be the continental shelf of the Bering Sea. In spite of intensive biological activity, a considerable fraction of copper added to shelf waters was transported to the area off Japan via the circulation in the Bering Sea and the Oyashio current.