Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 15 March 2010
Anthony Turton vice-president of the International Water Resource Association, explains why sulphur pollution is a bigger problem than carbon emissions.
We have recently emerged from negotiations at Copenhagen that focused on greenhouse-gas emissions. Most greenhouse gases are derivatives of carbon and much is said about carbon in the context of global climate change.
What is left out of this discussion is sulphur, which, in my professional opinion, is far more important to the immediate and short-term future of the South African economy than carbon will ever be.
Sulphur is relevant in South Africa in two important manifestations. Atmospheric sulphur, in the form of sulphur dioxide, combines with moisture in clouds and falls to earth as acid rain. Aquatic sulphur, in the form of sulphate salt, combines with water in underground mine voids and produces sulphuric acid, which in turn manifests as acid mine drainage (AMD).
As a professional, I first became interested in this topic when I was working at a national science council, responsible for developing strategic research programmes. AMD was becoming a major focal point in 2008 and I was monitoring data coming in from different places, with a view to understanding the problem better.
One day I was presented with data from Mpumalanga, where two rivers were being monitored. One of them drains an old coal-mining area and had very low pH [highly acidic], as one would expect from AMD. The second river was perplexing because it had an even lower pH but it did not drain a mining area.
I puzzled over what the explanation might be.
Then it dawned on me: the highly acidic water from the non-mining area was a manifestation of atmospheric acid deposition, caused by the combustion of coal in the Mpumalanga area.
So, while we were starting to focus on AMD as a national problem we were ignoring the atmospheric deposition of sulphur.
I started to ask questions and, to my amazement, discovered we have no reliable public-domain data on the total deposition of sulphur at national level.
Why is this important?
Simply stated, acid rain reduces the pH of [acidifies] soil. In certain soil types, aluminium is present as a trace element. Under acidic conditions, this aluminium is released. If the crop being grown is maize, then two things occur. First, the cell division at the root tip is inhibited, resulting in a deformed root system, which stunts the plant, making it prone to drought.
Second, the pollen tubes become deformed. These tubes are visible as a tassel at the end of the mealie cob and their function is to provide passage for pollen grains to fertilise the plant, thereby allowing seed to set. In the presence of aluminium, these pollen tubes become deformed so pollination can no longer occur, resulting in crop failure.
What this means is that the continued combustion of coal as a foundation of our national energy security is starting to have a detrimental effect on our national food security.
More important, we do not have high-confidence data on which to base management decisions. For example, we need to generate geographic information system maps so that we can understand the [connection] between specific soil types and plumes of atmospheric pollution downwind of major points of coal combustion.
Then we need to quantify the total sulphur budget for the country. From this we can start to understand how big the AMD problem really is.
It is my hypothesis as a scientist that the total sulphur budget is so large for South Africa as a whole that the masses being deposited as sulphate in our rivers in the form of AMD are probably a small fraction of that being deposited on land by atmospheric pollution.
If this hypothesis is correct, then the economy will increasingly be at risk. Food security will be threatened as a result of our quest for energy security. The input costs of farmers will increase, specifically for limestone needed to neutralise acid rain, and this will push up prices for food.
The economy has grown by externalising the costs of mining onto society. While this achieved remarkable economic growth in the latter part of the 20th century, it can no longer happen, simply because ecosystems that absorb this externalised cost are now collapsing.
The most notable of these are our aquatic ecosystems, all of which are now highly stressed.
The Olifants River draining Mpumalanga is collapsing, specifically because of acidification.
In the final analysis, our economic prosperity will have to be predicated on a careful trade-off between energy security, food security and water security, which is why we need to merge these different policy strands.
Carbon is bad, but it is also global and it will kill us in the next century.
Sulphur is here and now, manifesting as reduced maize output and rising prices in the near future. So where are we to place our priorities as a nation, Mr President?