Cd, Zn, Ni and Cu in the Indian Ocean

• Published in: Deep Sea Research Part A. Oceanographic Research Papers
• Main Authors: Saager, Paul M., Baar, Hein J.W. de, Howland, Robin J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1992
• Subjects: Antarctic; Antarctic Ocean; Indian; Pacific; The Antarctic; Antarc*; North Atlantic
• Online Access: https://hdl.handle.net/11370/e0d23582-ad8a-46df-bdc8-028d9880a2ea; https://research.rug.nl/en/publications/e0d23582-ad8a-46df-bdc8-028d9880a2ea; https://doi.org/10.1016/0198-0149(92)90017-N; https://pure.rug.nl/ws/files/3333750/1992DeepSeaResASaager.pdf

Vertical profiles of dissolved Cd, Zn, Ni and Cu in the Northwest Indian Ocean (Arabian Sea) exhibit a nutrient type distribution also observed in other oceans. The area is characterized by strong seasonal upwelling and a broad oxygen minimum zone in intermediate waters. However, neither Cd, Zn, Ni nor Cu appear to be affected by the reducing conditions, in contrast with earlier reported observations of Mn, Fe and rare earth elements. Low Cd/PO4 slopes in surface waters of about 0.15 nM/µM are in good agreement with slopes typical of surface waters in other oceans. Deep water slopes, however, increase from 0.5 nM/µM to 0.85 nM/µM going inshore. These slopes are much higher than published for the deep North Atlantic and North Pacific Oceans, yet comparable to the high Cd/PO4 slope recently published for the Antarctic Ocean. Deep water cadmium-phosphate ratios increase with the age of the deep water from the Atlantic through the Antarctic and Indian to the Pacific Ocean. Slopes of Zn/Si (0.062 nM/µM) are about the same as found in the Pacific Ocean, deep water ratios are about 30% higher. The slopes Ni/Si (0.054 nM/µM) are in good agreement with previous reports from the Indian Ocean. The Cu profile shows evidence of surface water inputs, regeneration in intermediate and deep waters and benthic fluxes, and is further influenced by intensive scavenging, notably in surface waters.