Green algae flourishing in the near-stagnant Vaal River, summer 2012
The Vaal River in central South Africa certainly deserves its name: the word in Afrikaans means murky or cloudy. But this season there is an ironic twist to things. The river has gone bright green and is totally opaque due to the growth of algae. Bacterial growth is flourishing on the nutrients in the water, phosphates and nitrates, resulting in eutrophication.
Not the murky river any more – the yucky river. Despite being the third-largest river in the country and the one that supports our urban heartland, the Vaal is a dirty industrial ditch and there’s not much hope in sight that it will be cleaned up anytime soon. Instead of attending to the green woes of our planet, our politicians and businessmen are busy lining their pockets with the golden wealth of the country.
Oddly enough the immediate cause of the pollution is that we have had both too little rainfall and too much! Rains this season (2011-12) have been poor and very scattered. The river is very sluggish and the water is warm. But last year (2010-2011) we had a massive flood. This cleaned out the invader weeds including the massive floating mats of water hyacinth and parsley weed. Noxious as these plants are, they do one important thing for the river: they suck up the nutrients and improve water quality. With no weeds, there has been nothing to perform this job and the algal bacteria have taken advantage.
You just can’t win! Drought and flood have combined to pollute the Vaal with organics. What we can’t see are the inorganic suspended solids – the cyanide from mines, the mercury from factories, home detergents, plastics and other chemicals and pollutants that float in suspension, flutter about, or creep along the bottom as a murderous sludge.
When the Vaal got its name from the early Voortrekkers nearly 200 years ago there was none of this gunk in the river. It was dyed a murky grey-green by surrounding vegetation and minerals leached from the geology. When it flooded it turned browner from silt. That was all pretty clean stuff. Now we are witnessing one of the most unlovely products of industrial civilisation and human carelessness: a murky river carrying all our waste to the sea to kill the fishes.
The dilution capacity of all our rivers is being seriously taxed and we are making the water on which our lives depend unusable except at great clean-up cost. The free ecological services performed by nature can no longer cope. Now we must pay heavily for potable water. How’s that for bad economics?
Read a report on what the authorities are NOT doing about it while “taking samples”.
I hazard to think what the oxygen content is!
The Vaal hardly exists in a chemostatic state but man, one push too far and we could see a collapse? Has there been any measure in Cyanotoxins?
I hope it is flushed and swells and lest hope fish like yellows can extend spawning beyond this.
B