[img_inline align=”right” src=”http://padnws01.mcmaster.ca/images/Slater_Greg.jpg” caption=”Greg Slater uses chemistry to study the sources and fate of organic contaminants in the environment. Photo credit: Graham Janz”]What is the connection between a bacterium four kilometers underground in a South African gold mine, the polluted water of Hamilton Harbour and a cutting edge research lab at McMaster University? The answer, according to Greg Slater, is chemistry.

Slater, an assistant professor in the School of Geography & Geology at McMaster and Canada Research Chair in Environmental Isotope Biogeochemistry, uses chemistry to study the sources and fate of organic contaminants in the environment. He observes, “Understanding what the major sources [of contaminants] in an environment are helps us understand where we should focus our clean-up efforts.”

Common environmental contaminants include PAHs, which are generated by burning fuels such as coal and petroleum; PCBs, which have been used in specialized industrial roles; and DDT, which has been used as a pesticide in agriculture and to fight against malaria. These chemicals all fit into a category called 'organic contaminants' because they contain the element carbon.

These contaminants are found throughout the world. Our own Hamilton Harbour is known to contain PAHs and PCBs.

In collaboration with other researchers at McMaster and with the Canada Council for Inland Waters (CCIW), Slater is developing a project to determine if the contamination in the Harbour is all coming from industrial activities, or if other sources, such as vehicle emissions, are also contributing.

In order to determine where contaminants originate, Slater uses chemical techniques that involve analyzing the carbon in the samples he collects for different compositions of isotopes. An isotope is similar to a normal atom except that it contains a different number of particles called neutrons. Ninety-nine percent of carbon has six neutrons. However, carbon also has two isotopes, one with seven neutrons and one with eight.

With the help of funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), as well as the Canada Research Chairs Program, the Canada Foundation for Innovation (CFI) and the Ontario Innovation Trust (OIT), Slater has been able to develop a cutting-edge lab at McMaster capable of measuring the isotopic composition of the carbon in organic contaminants. This lab is one of a handful of labs in the world focussed on this innovative type of analysis.

Different types of contaminants, such as industrial wastes and vehicle emission, have unique carbon isotope compositions; therefore, by determining the composition, Slater is able to determine whether the contaminants in Hamilton Harbour came from industrial sources or from emissions from burning fuel.

Slater also points out that, “Environmental toxicity, or the risk the contaminant poses to us, has a lot to do with how long it stays in the environment.” Using similar isotopic tools Slater can also investigate how fast the contaminants are breaking down – the slower they break down, the more dangerous they are. By understanding where contamination is coming from and which contamination is most dangerous Slater's research is helping to ensure that the worst sources of pollution are cleaned up first – stopping the problem from getting any worse.

Slater also has some ideas about how to clean up the contaminants that are already in the water – or more accurately, how to get bacteria to clean up for us. He says, “I'm very interested in trying to understand if bacteria in the harbour sediments are breaking down and metabolizing any of the organic contaminants to any significant effect. There are bacteria that exist in nature that can [break down contaminants] – the question is how much are they doing it and where.”

Slater is studying the chemical and metabolic reactions that allow bacteria to use carbon contaminants as a food. This research is crucial because, “We have to understand how they do this, and how to optimize it, so we can most effectively clean [contaminants] up.”

As bacteria munch away, they fill themselves up with carbon. By analyzing the bacteria, Slater can determine what kinds of contaminants they are eating. Slater says, “I want to look and see whether the bacteria are actually eating the contaminants and to better understand how long [the contaminants] will last and whether we can encourage [the bacteria] to do this faster. If we find that they are doing it, but certain chemical or geochemical conditions would help them do it better or faster, we could consider that as a remediation strategy.”

The applications of Slater's work on bacterial metabolism are truly out of this world. Not only do microbes clean up after us, they also give insights into the possibility of life on other planets. Bacteria are some of the most basic life forms and they are found in the most extreme and primitive environments on earth including South African gold mines, several miles underground. By studying the isotopes in the waste that the bacteria in these mines leave behind as they chomp up carbon, Slater is learning what signs of bacteria to look for in other extreme environments – like Mars.

Although Slater's research often takes him around the globe, he observes, “It's all very connected. I'm interested in the origins and basis of life and in the contaminants that are more or less affecting the basis of our life in Hamilton.”

Chemistry is a remarkable science. The chemicals and reactions that drive our society have contributed significantly to the pollution and contamination of our environment. Now, researchers like Greg Slater are using chemistry to clean it up.