Interview with Dr. Karen Johannesson, Tulane Earth and Environmental Sciences

Hi, my name is Karen Johannesson. I'm a geochemist here at Tulane. I study trace elements in the environment and particularly their chemical speciation. One of the reasons why I study trace elements is because in some cases trace elements can be very toxic, things like arsenic and mercury. Other times they are essential nutrients or micronutrients for certain organisms. For example, molybdenum and vanadium can be very important in a number of enzymes that are necessary for life on the planet. My research group focuses on fieldwork, laboratory experimental work, and we also use mathematical models to help us better understand how trace elements behave in the environment. Most of our laboratory experiments are conducted in, in this room, in this particular laboratory. We also have a clean room over in another building where we do experiments where we need to keep the metal concentrations very low. Over here we have an example of one of our glove boxes where we conduct experiments at very low oxygen levels for the atmosphere. This is because many of the trace elements that we study are highly reactive with particularly oxygen, so we want to keep the oxygen level very low. We've been working a lot on arsenic, as I've mentioned, tungsten, and also the rare earth elements. So one of the reasons why we're studying arsenic is because roughly 100 million people in West Bengal, India, and Bangladesh in South Asia, in the Ganges-Brahmaputra delta region, are currently exposed to high levels of arsenic in their drinking water. And their drinking water source is groundwater, shallow groundwater. It's been estimated that 1 in 5 deaths in Bangladesh Uh-huh. Is due to drinking water with high arsenic. So it's a very large problem. It's actually been referred to as the greatest natural disaster in human history. Um, it looks like we probably have a similar, at least groundwater issue in southern Louisiana in terms of having high arsenic. Um, and that probably is because we have a very similar geologic setting here in the Mississippi Delta to what we see in Bangladesh and India, mainly a large delta plain with a lot of low-lying land that's very swampy. So we are trying to understand the processes that lead to the elevated arsenic in groundwaters in West Bengal, India, as well as here in Louisiana, with the idea that if we can understand those processes better, we can perhaps mitigate against people using these drinking waters, or when they're drilling and installing a well, for example, they can recognize properties of the aquifer sediments or the waters or the setting, the general setting, and say this is not a good place to put a well because this is going to be a place that's going to develop groundwaters with high arsenic and then people will be getting sick. Another area of research that my students and I have been involved in is understanding the fluxes of trace elements to the coastal ocean by groundwater. So we're interested in this because many of these trace elements again can be toxic, and some are, are also nutrients or micronutrients, so they could affect the biology in the coastal ocean. They also have some paleoclimatic applications, in particular our work on the rare earth elements and radiogenic neodymium isotopes. So this work has taken us throughout a lot of the Gulf Coast, as well as to Florida, Rhode Island, and the great state of Hawaii, which has been a lot of fun.