Understanding soil contamination

Dr Michael Angove has devoted his career to understanding the impact of contaminants on our soil, and what happens when they end up in our waterways

Dr Michael Angove loves the outdoors. “It’s timeless,” he said. “You can just enjoy being in the world, and watch it unfold in a natural way.” No wonder this avid bushwalker and photographer married his love of science with his passion for the Australian bush.

Dr Angove is an expert in environmental chemistry and Head of the Department of Pharmacy and Applied Science. He has devoted his career to understanding the impact of contaminants on our soil, and what happens when they end up in our waterways.

Heavy metals

Dr Angove specialises in anthropogenic soil contamination: pollution caused by human activity in the natural environment. Based at La Trobe’s Bendigo campus, Dr Angove’s home town boasts one of the most contaminated soil environments in the world. “During the Victorian gold rush, more than 5,000 registered mines were formed, with the largest concentration of deep shafts anywhere in the world,” explains Dr Angove.  “A lot of the gold in this region was sulphide ore. When you dig it up, it has high levels of arsenic and lead, uranium even.”

Mining’s legacy is an ongoing concern for the Goldfields region. New subdivisions are planned around historical mining activity, and the Bendigo City Council has to contend with managing precarious things like tailings: the piles of dirt dredged up by eager gold miners in the 1850s. “Mining tails are lying all around town,” said Dr Angove. “As kids we used to get Esky lids and slide down the bigger tailings, but they have significant contamination. In recent times, the Council have sealed them with concrete but, for many years, they were exposed. And rainfall, for example, transports soil remnants from tailings into our waterways. The Bendigo Creek contains heavily contaminated waters and sediments laden with arsenic, lead and mercury.”

A Bendigo native, Dr Angove grew up surrounded by soil contamination. As a scientist, he has sought to understand the intricate chemical mechanisms involved. “There has been a lot of research on soil environments, particularly in relation to heavy metals. There has been far less work on understanding what happens to organic molecules that are contaminants,” he said. “My research examines the interaction between compounds – in particular pharmaceuticals and fire retardants – and soil and sediments to identify their impact on the environment and how transportable that contamination is.”

Drug disruptors

Thanks to advances in analytical technology in the past 20 years, pharmaceutical compounds can now be identified in the water cycle including surface waters, wastewater, groundwater and even drinking water. “Pharmaceuticals, along with a range of other synthetic materials,   including plastics and detergent, have been identified as endocrine disruptors,” said Dr Angove. “They are compounds that behave like estrogen and their presence in our environment has an impact on wildlife and human health. In Europe, for example, some of the river systems have been significantly impacted because the fish have been feminised by the presence of endocranially active compounds. As a result, there are less male fish and less fish more generally. Same for frogs. With humans, we know that the endocrine system is linked to breast and prostate cancer, and the early onset of puberty in women. Research confirms that our increased exposure to endocrine disruptors has led to an increase in the number of these conditions.”

Dr Angove is currently examining the presence of common antipsychotic drugs – including those used to treat schizophrenia, bipolar disorder and depression – in wastewater treatment plants. “Drug compounds are usually metabolised by the body before they are excreted, but some, such as antipsychotic drugs, are excreted unchanged and in an active form. We are currently looking at the environmental impact of this in a wastewater setting, to determine how these compounds behave. There are a number of possible things that can happen. They can break down more quickly if they are exposed to bacteria and microbiology, or they might be held under anoxic conditions where they are preserved for a very long time. We are trying to understand some of these processes.”

Earth, water and fire

Dr Angove is also an expert on what happens when bushfires, catchments, and phosphorous-based fire retardants collide. It’s an important question for Australia, where the number of bushfires has increased by 40% over the past five years. “One way of fighting a bushfire is to drop fire retardants from a helicopter,” he said. “The idea is that when the phosphate burns it creates a barrier between the actual fuel and the fire, and slows down the fire front. Retardants are mainly used in water catchment areas, because the terrain is often inaccessible to fire crews. But if the fire front doesn’t reach that area, what we end up with is very high concentrations of phosphate, which can impact water systems.”

“Of course you don’t want those environments to burn either, because you end up with that burnt material going into water catchments. We did a lot of research on the 2003 and 2008 fires that impacted catchment areas in the Victorian High Country around the Thompson Dam. We examined the problem from a pure physical chemistry point of view – using core minerals to identify the mode of chemical interaction between dissolved organic and inorganic compounds’ particulate surfaces – to determine what happens once that material ends up in the water system. We found that what you end up with are some compounds that are endocranially active.”

In all environments, Dr Angove is committed to understanding what’s going on at a chemical level. “There is some satisfaction in going back to basic science to understand the exact chemical mechanisms involved,” he said. “I started working on endocrine disruptors at a time when it wasn’t clear that many of these compounds were a problem. Today, we are more informed and more aware. Understanding the chemical interactions caused by human activity will play a part in better managing our environment, and what we put into it.”

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