Enperitus Pty Ltd

Dust – they say it’s not impacting the vegetation!

Have you heard this before?

Have you been to mine sites where a layer of dust covers the vegetation alongside the road?

Have you seen a busy exploration area where no dust management is in place and yet it covers the vegetation?

Have you been told that the vegetation has recovered after the first rain of the season?

And then there’s the compliance issue. Ministerial conditions often require dust monitoring and mitigation but are simply developed based on the Precautionary Principle. There are often no trigger values, and no proven effects of dust on vegetation.We know that ambient dust levels are high in our semi-arid and arid environments and that the vegetation have adapted to cope with these high levels.

This is especially frustrating after a visit to Karijini National Park, where our regulators that push for dust management (in our EMPs) do not address dust in this NP in the immediate term. You ask yourself whether or not our land management practitioners really believe that dust is a problem out there.

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In my efforts to make sense of all of this, I found that few studies have considered what levels of fugitive dust will impact vegetation in Western Australia. Without this information, any efforts to monitor or manage dust generation are superficial and are simply there to satisfy legal requirements. This, to me, is an inefficient use of resources and a waste of everyone’s time because it may not protect the environment at all.  Gillian Turner has since conducted an excellent research study in this area to fulfill the requirements for a Masters of Science thesis.

Turner, Gillian Frances. 2013. Vulnerability of Vegetation to Mining Dust at the Jack Hills, Western Australia. Master of Science Thesis, School of Plant Biology, University of Western Australia.

Key findings of Gillian’s work include:

  • Acacia aneura and A. rhodophloia were found to be very good indicator species (they are sensitive to dust loading and broadly distributed in Western Australia).
  • Plants with certain traits i.e. flat, striate leaves were more susceptible to the effects of dust.
  • Fugitive dust (5g/m2) reduced the physiological response of stomatal conductance by 50%.
  • Some species were observed dead or heavily stressed at these levels (5g/m2), other species were unaffected by dust.

While these findings may not be applicable in every situation (or region), they provide one step forward in our understanding of the effects of fugitive dust on vegetation. In order to increase the efficiency of implementing a compliance program and striving for excellence, we need to understand the reasons for mitigating a potential hazard. Monitoring dust levels without a proven and trusted trigger value is a waste of time and effort. Sending out a water truck once a day may be ineffective or on the other hand, not needed other than for OHS requirements. Monitoring some plant species health may not be needed if they are not susceptible to the effects of dust.

Question what you are doing in order to reduce costs, improve efficiency and continually improve your compliance program.