The 1996 IOC contaminant baseline survey in the Atlantic Ocean from 33 degrees S to 10 degrees N: introduction, sampling protocols, and hydrographic data

The third in a series of cruises designed to establish the present-day conc entrations of trace elements and synthetic organic compounds in major water masses of the ocean, the 1996 Intergovernmental Oceanographic Commission C ontaminant Baseline Survey occupied six vertical profile stations in the su btropical and tropical Atlantic. Underway surface samples also were acquire d in the transects between these stations. This paper uses the temperature, salinity, oxygen, nutrient, and chlorophyll results from the cruise to set the hydrographic background for the other papers in this special volume. M ajor features sampled during the surface transect include the Brazil Curren t, the South Equatorial Current, and the offshore Amazon Plume. Utilizing t he above parameters to identify water masses, we observed Antarctic Bottom Water (AABW) that ranged from a relatively undiluted form at 33 degrees S ( Station 10) to a highly attenuated form at 8 degrees N (Station 6). Similar ly, North Atlantic Deep Water (NADW) was obtained in various mixing stages along its flow path, and samples of NADW and AABW exchanging through the Ro manche Fracture Zone to the eastern Atlantic basins were also taken. In add ition to these deep water masses, representative samples of Antarctic Inter mediate Water and Circumpolar Deep Water were acquired. Besides standard hy drography, these data also were used to verify the sampling integrity of th e trace metal-clean, Go Flo bottles deployed on a Kevlar hydrographic cable . (C) 1999 Elsevier Science Ltd. All rights reserved.