Geology for Global Development

Geology for Global Development

Bárbara Zambelli Azevedo: Phosphorus Crisis – A Food Crisis?

Take a look and try to identify anything around you that has phosphorus as a component.

Phosphorus – the P element – is critical for life, like oxygen, nitrogen and carbon, being present in every plant, animal and bacteria. It constitutes cell walls, DNA, RNA and ATP, which transports energy to the brain. Our bones and teeth include phosphorus.

Now look again and you might see that phosphorus is more present in your daily life than you first imagined.

We obtain our phosphorus by eating plant- and animal-based food. Cattle obtain their phosphorus from feed, grazing and supplements. On the other hand, plants obtain phosphorus from the soil by their roots, transporting, absorbing and storing it to where it is needed. If a plant doesn’t get enough P, their growth is strongly affected, the formation of fruits and seeds decreases and crops yield less.

Image 1: Coffee crops in Minas Gerais, Brazil (photo: Bárbara Zambelli)

Image 2: Banana crops in Gran Canária, Spain (photo Bárbara Zambelli)

The phosphorus (P) present in soils is either natural or added by the use of fertilisers, manure and organic residues. Natural P exists on soils as a result of phosphatic bedrock weathering. As a geological feature, it is not evely distributed on the Earth’s surface and it can take a long time to form, such as a million years.

Why should we worry about phosphorus?

Phosphorus is a non-renewable resource that cannot be replaced or synthesized for plant nutrition. Moreover, it is one of the most reactive nutrients in the soil, being easily transformed into forms that are unavailable to plants. A study shows that about 90% of all the phosphorus mined worldwide is used for food production. According to USGS, 88% of all reserves are under control of 5 countries: Morocco, China, Algeria, Syria and South Africa. Morocco is by far the country with the largest reserve, holding 74% of the world’s phosphate reserves. Therefore, most of the countries rely on phosphorus imports to sustain agriculture. The scarcity scenario is not only physical but also geopolitical, economical and managerial.

Image 3: phosphorus mine (photo: Alexandra Pugachevsky, source)

The world’s population is growing steadily, projected to reach 9.7 billion people by 2050. In this sense, feeding almost 2 billion new mouths by 2050 is an increasing challenge. Growing food demand equals growing phosphorus demand.

The reserves of phosphorus will be depleted sooner or later. Some authors argue that the ‘phosphorus peak’ will happen pretty soon, in 2030, while others says that it won’t happen before 2100. There is no consensus because different studies are based on different methodologies and assumptions about demand and uncertainties about supply.

In this manner, to achieve SDG 2 and assure that everyone has access to safe and affordable food until 2030, we must change the way we use, source and distribute phosphorus among the global food production.

Another important issue is the biofuels production. With an increasing pressure to reduce oil consumption and greenhouse gases emissions, accordingly to the Paris Agreement on COP21, many countries are turning to biofuels, such as alcohol made from maize or sugarcane. These crops also needs phosphorus and use land that could be used for agricultural purposes.

What about the environment?

While phosphorus is a scarce resource vital for agriculture, it is also a pollutant of waterbodies. Not all phosphorus used as fertiliser is absorbed by plants. Some phosphorus stays on the soil and is later carried to streams, rivers and lakes. This anthropogenic input of phosphorus generates an anomalous concentration of P nutrient in water bodies, encouraging the growth of blue and green algal and causing algal blooms. The increase of nutrients and then algae and higher plants is called eutrophication.

Eutrophication can be toxic or deeply change the ecology of the waterbody. It produces many undesirable effects regarding human society, such as drinking water problems, decrease of seafood production and presence of toxins in drinking water and seafood.

Image 4: eutrophication at a wastewater outlet in Potomac River, Washngton D.C. (photo: Alexandr Trubetskoy, source)

Another environmental problem concerns mining tailings. Phosphatic rocks, as a result of its chemical composition, may contain notable amounts of naturally occurring radioactive materials. The process of converting the phosphorus ore to phosphoric acid (that can be used as fertiliser) or elemental phosphorus produces phosphogypsum as a primary waste by-product. These processes concentrate in the waste most of the naturally occurring thorium and uranium and its decay products, such as radium and radon. If proper attention is not given to this waste, it risks contaminating the air with radon gas (radioactive), and groundwater, affecting farmers and the wider population.

What can we do?

We have to think in ways to reduce the consumption, reuse and recycle.

A simple way for reduce phosphorus consumption is actually not a brand new idea. The answer relies on the symbiotic association between a small fungus and plants’ roots called ‘mycorrhizal’. The symbiose, which is a win-win relation, occurs when the fungus bounds to the roots. This fungus grows faster and it is more efficient on searching for phosphorus than the plants’ roots. So it provides phosphorus that were on the soil but could not be absorbed by the plant and, in return the plant nourishes it. Therefore, by using mycorrhizal association it possible to reduce the amount of phosphorus fertilisers needs of a crop, by enhancing its P absorption by the plant. In this video, Dr Mohamed Hijri explore use of mycorrhiza to optimise phosphorus use for agricultural purposes. Another way of reducing consumption would be encouraging diets that has fewer aliments that are phosphorus intenses, like meat and dairy products.

About reuse, we can think on reducing losses on the food chain, rubbish bin and animal manure, for example. Those are all sources of phosphate that cannot be overseen.

Concerning recycling, it is important to highlight the safe use of wastewater for agricultural purposes. The UN-Water has a project on this issue can be downloaded here. Its usage is already bigger than expected! Almost 100% the phosphorus eaten in food is excreted. The sewage treatment as a way to recover phosphorus present in human screta for agriculture, although controversial, is already being done in Sweden for example. Since the population is growing and a big part of it will settle down in peri-urban areas in mega-cities in the next few years, a big attention must be given to these places. They are becoming a ‘hotspot’ for phosphate production.

To know more about the phosphorus crisis and opportunities click here, here and here.

How do you monitor an internationally disruptive volcanic eruption? How can you communicate SDGs in an Earth Science class? Jesse Zondervan’s Nov 13 – Dec 13 2017 #GfGDpicks #SciComm

Each month, Jesse Zondervan picks his favourite posts from geoscience and development blogs/news, relevant to the work and interests of  Geology for Global Development . Here’s a round-up of Jesse’s selections for the past four weeks:

Bali’s Mount Angung started erupting ash this month, and a post on the Pacific Disaster Center’s website gives you an insight into the workings of Indonesia’s early warning and decision support system. How do you monitor an internationally disruptive volcanic eruption?

In Japan, eruptions in 2016 were preceded by large earthquakes (MW 7.0). A team of researchers used Japan’s high resolution seismic network to investigate the underground effects of earthquakes and volcanoes. How does an earthquake affect a volcano’s activity?

Next to plenty of disaster risk stories – including the simple question: why can’t we predict earthquakes? -, this month brings you a computer simulation tool to predict flood hazards on coral-reef-lined coasts and some thoughts on how to communicate SDGs in an earth science classroom.

Have a look!

Education/communication

The UN Sustainable Development Goals – what they are, why they exist by Laura Guertin at AGU’s GeoEd Trek blog

GeoTalk: How an EGU Public Engagement Grant contributed to video lessons on earthquake education by Laura Roberts-Artla at the EGU’s GeoTalk blog

Credit: Michael W. Ishak, used under CC BY-SA 4.0 license

Disaster Risk

Disaster Geology: 2017’s Most Deadly Earthquake by Dana Hunter at Scientific American

Can the rubble of history help shape today’s resilient cities? By David Sislen at Sustainable Cities

The underground effects of earthquakes and volcanoes at phys.org

Why Can’t We Predict Earthquakes? By David Bressan at Forbes

Detecting landslide precursors from space by Dave Petley at the AGU Landslide Blog

Ocean Sediments Off Pacific Coast May Feed Tsunami Danger by Kevin Krajick at State of the Planet

Life-saving technology provides alert as Bali’s Mount Agung spews ash, raises alarm at Pacific Disaster Center

Climate Change Adaptation

Scientists counter threat of flooding on coral reef coasts by Olivia Trani at AGU’s GeoSpace blog

Check back next month for more picks!

Follow Jesse Zondervan @JesseZondervan. Follow us @Geo_Dev & Facebook.

Photo Highlights – 5th GfGD Annual Conference

Kindly hosted and supported by the Geological Society of London, our 5th Annual Conference had the theme “Cities – Opportunities and Challenges for Sustainable Development”. The event gathered more than 130 participants, with diverse speakers from the public and private sectors, academia and civil society! Find resources online . Thanks to Jesse Zondervan (Plymouth University) for taking and editing photographs.

Robert Emberson: Microplastic – Too Important to Ignore

Anyone lucky enough to catch any of the BBC’s recent new series Blue Planet II will have noticed that each episode devotes a portion of the time to the impact humans have on the oceans. A breathtaking series of shots from a recent episode detailed the heart-wrenching demise of a baby whale, possibly poisoned by its mother’s milk due to toxins from plastic pollution. Vast quantities of plastic now cover the surface of the ocean, a point the series makes well. We’re now increasingly aware of the risks this plastic introduces, but there’s one part of the problem that scientists have only recently begun to appreciate – so called ‘microplastic’.

Toothpaste is a notorious source of ‘microbeads’.

Microplastic is simply defined as those bits of plastic waste smaller in length than 5mm. This famously includes ‘microbeads’ used in some cosmetics and toothpastes, but there’s also contribution from artificial fabric fibres and degraded bits of larger plastic waste. Because we often can’t see the microplastic with our naked eyes, it goes much more unheralded in contrast to the floating islands of waste bottles and packaging, but that invisibility makes it a more insidious monster.

We still don’t know much about the sources and pollutant pathways associated with microplastic. The United Nations Environment program suggest that cosmetic sources of microbeads have been a pollutant for at least the last 50 years but since then it has often been forgotten as a potential pollutant. In recent years researchers have observed river and ocean sediments in a number of global locations with high levels of microplastic accumulation, while a collaborative investigation between journalists and scientists has revealed that a significant proportion of tapwater in a wide range of urban settings contains measurable microplastic. It seems, then, that this is a problem of growing importance.

The impact for biology is also an emerging subject of study. Microplastic can accumulate either physically in organisms or the toxins generated as it breaks down can poison creatures all across the food chains. Ecologists regularly note the potential for pollutants and toxins to become more concentrated in species further up the food chain, and this is just as true for microplastics. In addition, the plastic compounds have the potential to adsorb other toxins and contaminants onto their surfaces; this mechanism of pollution delivery is poorly understood but considering that the smaller the plastic fragments the greater the proportion of surface area that could be utilised in this way, it could well play a role.

From a sustainability perspective, these plastic fragments could be a timebomb. Not only do they pollute water systems and potentially contribute to poisoning aquatic species, but the impacts could grow for years to come. Even if in the future we shift to a more sustainable model of consumption and production, and recycle the majority of the plastic we use, we will still have to deal with a microplastic legacy of our current plastic use. At present, we have only recycled or incinerated around 20% of our plastic waste meaning that the remaining 80% could disintegrate into fragments over time. It’s clear that understanding how this material enters our water systems and ecosystems is thus of paramount importance.

Microplastic particles on a beach. Image credit: NOAA

And here’s where geologists can play a role. River systems are a topic of interest and study for so many earth scientists, whether geochemists, hydrologists, or geomorphologists. Many geologists routinely sample rivers to analyse the amount of sediment within, or the chemical fluxes. Microplastic fits within the same areas of study; it has been described as a “structural” rather than chemical pollutant – which essentially means it forms part of the solid load of a river – just like regular sediment. Naturally, the physical properties of the plastic differ to sand or clay (the difference in density is particularly important), but the methods we could use to calibrate our microplastic models would be similar to those used to assess suspended or bedload in rivers.

Some scientists are already using these techniques, but much more work needs to be done to effectively understand the long term evolution of the fragments in natural waters. How, for example, do storms and floods affect the storage or mobilisation of microplastic in river sediments? Using hydrological tools to fingerprint the sources of microplastic might also help form a better picture of where exactly these pollutants enter the water systems, which still in many locations remains a mystery. Hydrological models incorporating microplastic transport would certainly help ecologists plan for the impact pollutants would have on aquatic species, and this is exactly what hydrologists could bring to the table.

The adsorption of chemicals to the surface of plastic is similar to other particles in the water flow – particularly colloids. Recent studies have shown that microplastic can adsorb heavy metals (another key set of pollutants) onto their surfaces, and thus deliver these pollutants to a range of species that might ingest the plastic. These are processes well understood by geochemists, offering a chance for the geochemistry community to collaborate with ecologists and conservation researchers.

As with a number of the issues standing in the way of achieving the Sustainable Development Goals, addressing microplastic pollution will require extensive cooperation between scientists of different stripes, policy makers, and polluters. A recent study suggests both that plastics from road wear by cars are the biggest contributor in parts of Europe and that sewage treatment efficiency is an important variable. Resolving these kind of complex infrastructure and ecological problems should certainly engage a cross-section of researchers.

Geologists can find their role in solving this problem as scientists, but importantly as regular citizens too. Limiting plastic use and advocating for recycling are already part of the arsenal of tools we can use to improve the sustainability of our lives; geologists shouldn’t forget that they can contribute in these ways too. Research is still ongoing to understand the range of products and plastics that either contain or form microplastic pollution, but we should all keep track of this research to ascertain how we can minimise our microplastic footprint. We need drinking water more than any other resource, and keeping it unpolluted by tiny plastic particles is an imperative.

Robert Emberson is a science writer, currently based in Victoria, Canada. He can be contacted via Twitter (@RobertEmberson) or via his website (www.robertemberson.com).