October 27, 2017

Breaking down diesel in Yukon contaminated soils

Mycoremediation is the use of fungi to break down organic compounds and pollutants. Mushrooms naturally recycle hydrocarbons. This is particularly the case for those that feed on wood lignin, the hardest part of wood to decompose which is similar to polycyclic aromatic hydrocarbons. Some species also absorb heavy metals from the soil (without addressing the problem of their disposal however). The delicious Shaggy mane (Coprinus comatus) is one of those: thus avoid harvesting in contaminated soil.

We have already mentioned several decontamination projects in Quebec. In the Yukon, a project led by researcher Kawina Robichaud of the Université de Montréal has been running for five years. She compared the effectiveness of different soil amendments at two heavily polluted sites near Whitehorse, one impregnated with diesel, the other with waste oil and other pollutants. Ordinary domestic compost, willow, or fungi were applied alone or in tandem. Oyster (Pleurotus ostreatus) and turkey tail (Trametes versicolor) were the selected local mushroom species for the test because of their known ability to degrade lignin. 

The ecosystem approach with oyster mushroom, willow and compost) was most effective : 70% of the diesel was eliminated in the first three months. The efficiency of oysters, initially high, decreased rapidly. No significant reduction in the waste oils were obtained with Turkey tail, probably because it did not survive in the very dense and polluted soil of the pit. On the other hand, a species of the family Psathyrellaceae has spontaneously fructified, accumulating heavy metals. 

The conclusion is that the effectiveness of any method is not based on one single amendment, but on the various components of the ecosystem.These results were presented October 18 2017 at a conference organized by Montréal's Cercle des Mycologues

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