Celia Kelly
Distribution of iron from the hydrothermal vents of Rumble III and Brothers Volcanoes on the Kermadec Arc, New Zealand
Hydrothermal vents are not well studied as sources of iron to the oceans compared to the widely studied and modeled aeolian dust sources and the less understood sedimentary source. This project will attempt to quantify the amount and distribution of iron using discrete samples of iron (Fe) and manganese (Mn) taken from three vent sources of varying depth at Brothers and Rumble III volcanoes in the Kermadec Arc, New Zealand. Manganese samples will be used as an indicator of biological and chemical impacts on the distribution of iron from the vents. The area of interest is a volcanic arc that is created by the subduction of oceanic plates below less dense continental plates which draws water, biologic material, and other impurities that try to escape to through the crust, taking with it molten material. This 2,500km long span of the ocean floor has many incidences of active venting, which vary in depth from the sea floor at ~3km to the more shallow vents at ~200m. Not many studies have been conducted on the mechanisms and effects of the hydrothermal vents this region, especially regarding the impact of the vents as a source of iron. Vents have the potential to be a source to the surrounding water column and mixed layers of the surface. It is even more likely to be a source for the shallower vent sites of subduction zones rather than the more commonly researched deep vents of mid-ocean ridges. Based on this premise, it is proposed that the deeper of the vent sites to be studied, Brothers Volcano, will expel significant quantities of iron to the surrounding environment. More importantly to this project, studies on Rumble III, which rises to a depth of about 200m below the surface, will be a source of iron to the surface waters. This could be an important influence on local primary production. Areas in the ocean that are depleted in iron are a subject of interest and concern, since the iron is considered a limiting macronutrient in the High Nutrient Low Productivity areas. Although this region is not considered to be HNLC, it is close to the Southern Ocean, which is one of the major HNLC regions of the world. By understanding the amount of iron produced by hydrothermal vents, implications of the global budget of iron may be better known.