MUDDY WATERS by Sally Ingleton
(Shown 20th May on SBS)
The documentary Muddy Waters provides an insight into the sedimentation on the Great Barrier Reef between Cairns and Townsville and how it is destroying the reef. However, though the movie does try to portray opposing sides of the debate as to what is causing this sedimentation, many fundamental issues to the problem have been avoided or underplayed.
The video stated heavy metals as one of the causes of the sedimentation and "marine snow" on the Great Barrier Reef but failed to mention what heavy metals are or which heavy metals are thought to be contaminating the reef. This heavy metals argument was used a lot in attacking cane farmers but very little information was actually given on the subject. Contaminant heavy metals may enter the environment by a variety of human activities, not only cane farming. Such things as land fills or even galvanized roofing can contribute to a rise in levels of heavy metals in sediments.
Heavy metals such as mercury, cadmium, copper, and zinc occur naturally in sediment. The problem is distinguishing what are the expected natural levels of the substances, what is from human sources and what, if any, are risks to the environment. CRC research has shown that some naturally occurring metals, such as cadmium, build up higher levels of concentration over time by natural processes. This means that the natural levels of metals in some sediments may even be higher than levels measured in contaminated sediments, a situation that makes it more complicated for environmental managers to recognise and evaluate risks to the environment.
Despite the documentary it has been shown that the Great Barrier Reef itself is not under the most threat of heavy metal contamination derived from Townsville. The areas most prone to...