Measuring physical properties of hydrothermal plumes from Pele’s Pit
Most studies of hydrothermal plumes are usually conducted at mid-ocean ridges and there are few studies of hydrothermal plumes at volcanically active seamounts, such as Loi’hi (Lupton 1996). However, at both locations the hydrothermal plumes’ physical properties and structure are different compared to their surrounding ambient waters. Therefore, the purpose of this project is to study the physical structures and distribution of the hydrothermal plumes coming from Pele’s Pit. Additionally, this project will examine if temperature and salinity of the vent source has changed. In order to do these investigations of the hydrothermal plume, a series of tow-yos using the Conductivity-Temperature-Depth (CTD) package will be made. These CTD tow-yos will be transecting across Pele’s Pit where the plume would most likely be. The CTD will be measuring physical water properties such as temperature, salinity, pressure, and transmission of light. These properties can determine whether a plume is present and can determine density. This in turn can determine buoyancy flux and heat flux. (Speer and Rona, 1989; Little et al., 1987). Knowing physical properties of hydrothermal plumes are important. First, they are important because Pele’s hydrothermal conditions are constantly changing due to geological and other processes. In fact, changes in physical properties and structure can be an indicator for changes in geological processes. For example, Pele’s pit has been studied for chemical and physical properties for both before and after the collapse (Wheat et al. 2000; Glazer and Rouxel. 2009; Garcia et al. 2009). Over the course of 30 year in which these studies took place there are differences in values of what was collected. Glazer and Rouxel (2009) discovered within their own study a difference in hydrothermal fluids discharging from Pele’s Pit between their 2006-2008 samples and their 1996-1997 samples. The Hawaii Undersea Research Laboratory reported they believe that Pele’s hydrothermal system is returning to pre-collapse conditions (Figure 1). Therefore it appears that Pele’s hydrothermal vents’ properties are constantly changing on a relatively short time scale. Secondly, hydrothermal plumes play host to a unique group of organisms that rely on their chemical and physical properties.