Marine phosphate mining for dummies
Adam Hartman | The Namibian | 9 November 2016
WITH the debate around the sustainability, profitability and legality of marine phosphate mining swirling, the voice of a marine scientist was missing. The Namibian (TN) spoke to Bronwen Currie (BC), chief marine scientist at the National Marine Information and Research Centre at Swakopmund. Currie is recognised nationally and internationally for her work on ecology and marine biogeochemistry.
TN: How important is phosphate to Namibia’s marine environment?
BC: The phosphate targeted by seabed mining are concentrations of phosphorus-containing solid particles buried in the sediments on the continental shelf, also technically known as ‘phosphorites’. Phosphorus is continually cycled by bacteria in the marine environment from decaying marine organic matter such as excrement or dead algae that sink to the sea-bottom mud – similar to the decay process making compost on land. Dissolved phosphate goes back into the water to make the tiny plants in the sea (micro-algae or phytoplankton) grow to provide the basis of the productive food web in the sea. Another group of bacteria under special conditions in the sediment convert some soluble phosphate to phosphorites. It is these solid phosphorites that are targeted for mining. Mining the seabed for industrial minerals in the manner proposed has the potential to endanger the marine environment in many ways. Namibia’s waters are recognised as amongst the most biologically productive marine areas in the world.
TN: How could seabed mining destabilise the marine environment?
BC: The seafloor is an integral part of our marine ecosystem. Soft, muddy and sandy sediments are a continuation of the seawater above, alive with organisms forming a complex important habitat within the ecosystem. Mining will remove seabed sediments, including all the organisms living on and in the sediment. There are vulnerable species that play important roles in the functioning of the northern Benguela ecosystem off Namibia, in the same areas as proposed for mining. If allowed, phosphate mining will not be localised to one small area nor to small amounts of seabed being removed. Impacts in the sea are carried by water currents far and wide: they are not restricted to a mining ‘site’ mapped onto the seafloor, where initial excavation occurs. There is no way to erect boundaries to confine mining activity within the sea, and no way to shield the sea life. Ocean water off our coast is connected in water currents moving in all directions. If phosphate mining begins, we know that several shelf mining sites containing the deposits will be targeted. We should know what we are letting ourselves in for, and to know the cumulative effect that such mining could have on other established industries that rely on the present ecosystem functioning. Mining on the basis proposed will result in a continual sediment plume in the water to affect everything from the water chemistry to the tiniest and largest forms of sea life. Other concerns are the toxins and dangerously high levels of metals found in the deep anoxic sediments being exposed and suspended in the water during mining. These substances are presently safely held in the sediment structure, but when suddenly freed into the water during excavation, these substances could enter the food chain and slowly build up in fish and other marine organisms, ultimately affecting or contaminating these animals. Namibia’s seafood industry has strict food quality standards, so this is of great concern. Processing ‘raw’ sediments unloaded on land for beneficiation to a rock-phosphate product and possible further processing of rock phosphate to fertiliser pose waste disposal problems. If effluents are destined into the sea, there are serious risks of polluting inshore coastal waters. It must be remembered that in the sea, contaminants like heavy metals might disperse, but they do not disappear and build up slowly in the marine food-chain.
TN: Are there any pros in seabed mining?
BC: No one – including mining proponents – will dispute that mining is destructive, but the question is whether the benefits outweigh the damage. We do not yet have any satisfactory or scientifically-credible assessment of what the damage will be. We scientists at the ministry do not believe that the proposed mining will have ‘little or no impact’. Acquiring knowledge is always used as a pro by mining proponents: mining is a way of acquiring knowledge of geological deposits of interest, particularly in difficult environments. However, knowledge about environmental aspects should be and can be obtained by modern scientific techniques before mining, not during mining. It does not help to acquire such knowledge after the damage is done.
TN: Is phosphate mining on land something Namibia could explore instead?
BC: Phosphate mining globally to date takes place on land. While it has its own set of environmental considerations, common with seabed mining are large amounts of effluents and waste materials resulting from processing raw mined material to achieve a marketable ‘rock phosphate’ product. Some wastes are highly toxic, and their storage or removal has created major headaches for terrestrial phosphate mining. If Namibia wants to mine from the ocean, we should be aware that there are massive volumes of waste generated once the actual grains of phosphate are separated from the excavated marine sediments which will be transported to land by large vessels for beneficiation. Rock phosphate is not a high-priced rare commodity, so the scale of economy required for an economically viable phosphate industry in Namibia at present, the rock-phosphate market prices would require intensive mining of our deposits. This means a massive amount of waste must then be disposed of either on land, or into the sea. In many places around the world where terrestrial mining for phosphates takes place and fertiliser is produced, wastes are considered too risky to dispose into the sea (EU regulation): so in responsible countries, such waste is fenced off on land and kept away from human contact because of the potential threat to human health (e.g. Florida, USA). In countries where no such regulation is enforced (e.g. Togo, West Africa) the wastes produced from phosphate mining have flowed into the sea, causing serious problems of contaminated seafood to the coastal communities.With far less knowledge on how marine systems work, and with most sensible and responsible nations following a precautionary approach to ecosystem management within their ocean systems, there has been major reluctance to try phosphate mining in the sea.
TN: Are there examples where marine phosphate mining could serve as a warning for Namibia, or could serve as a model of best practice?
BC: The track record of phosphate mining should be a warning light to Namibia. Most recently, both New Zealand and Mexico rejected the environmental clearances to implement marine phosphate mining because the environmental risks outlined in their transparent EIA processes were considered to outweigh any benefit to their countries – even though both New Zealand and Mexico themselves use large amounts of fertiliser. There are also records of land and island-based phosphate mining causing serious environmental harm (as quoted Florida, Togo, also the island of Nauru). Seabed mining of other minerals or commodities may well take place in the future to coexist with other marine industries, but a comprehensively planned legal framework should first be prepared, taking into consideration the marine environmental concerns. For example, the Pacific Island nations have in recent years been preparing themselves with new legislation in the form of a Seabed Authority Act with designated institutional capacity, specifically to cater for seabed mining.
TN: Have you ever heard of phosphate recycling?
BC: Phosphorus is neither rare nor scarce in the world – it is part of every living cell, and is constantly being recycled by our bodies and by all living plants and animals. There is no danger of it running out! The natural way to grow plants and crops is by adding the phosphorus contained in manure or compost to the soil. To boost plant growth and to maximise intensive crop production, phosphorus concentrated and packaged into commercial fertiliser is applied to the soil. Overuse of commercial phosphate fertiliser globally over the last 50 years has resulted in excess fertiliser washing off from agricultural land into rivers and into the oceans, where this oversupply of soluble phosphate in either fresh water or sea water causes big pollution and even toxic problems. The obvious and logical global solution is to recycle phosphate, instead of adding more from mined sources. To recycle, we should be aware that animal excrement or manure – be it animal or human – is the richest, most abundant and continual source of phosphate on earth, becoming more and more plentiful as the earth’s population grows. So, recycling phosphorus – make it renewable instead of non-renewable – could solve three problems at once: provide phosphorus fertiliser to grow food for the ever-expanding human population; assist in recycling the ever-increasing volumes of sewage that the human population is producing, and limit the demand for mined phosphate. Already, countries such as Sweden, Britain, Finland and Germany are successfully using phosphate fertiliser that has been extracted from sewage for crop production. So, if we are really sincere about the sustainability of our planet, recycling phosphate from humans in order to feed themselves should be the way to go. As Namibians, we are bound closely to our natural environment. So, in the big global picture, let us ask ourselves: Is it really necessary to dig up the ocean, with all the risky uncertainties about how much harm this will cause?