Geology for Global Development

Geology for Global Development

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).

Heather Britton: Can Animals be Used to Predict Earthquakes?

One of the most common questions faced by the disaster risk reduction community relates to earthquake prediction (see this Geological Society briefing on prediction vs. forecasting). The disaster risk reduction community, however, would perhaps argue that improved buildings, reduction in poverty, and improved governance are a greater priority than predicting earthquakes. Even so, there are still many members of the international community focused on trying to identify ways to predict earthquakes, including through the study of animal behaviours.

Our understanding of where earthquakes are most likely to occur is improving, but our ability to predict when an earthquake will strike is lacking, often limited to the decadal scale at best. We also lack information on what the magnitude or size of an earthquake would be at that given point in time. If such a feat were possible, and an orderly evacuation could take place, lives could be saved. Many seismologists are of the opinion that the vast majority of earthquakes do not display early warning signals prior to the first p-waves reaching the surface, therefore earthquakes are likely to always remain stubbornly unpredictable. This does not mean that we will be unable to improve earthquake forecast, through probabilistic hazard assessment. It also does not mean that the disasters arising from earthquake are inevitable. We can still take significant steps to reduce exposure and vulnerability and reduce the impacts of earthquakes.

Other scientists disagree,  on the point of earthquake prediction, pointing to the anecdotal evidence which stretches back through historical archives around the world of animals predicting earthquakes far before modern technology would have us believe any indication of an earthquake existed. Is there any substance to these tales, and if so can it be used to support earthquake prediction?

Although devoid of substantial scientific evidence, the claim that early warning signs don’t exist fails to acknowledge the stories of animals abandoning their homes up to a month before an earthquake strikes. For centuries there have been reports of unusual animal activity prior to earthquakes: In 373 BC Greece it is documented that rats, weasels, snakes and centipedes abandoned their homes a month before a destructive earthquake struck, and in Italy toads disappeared from a pond where scientists were analysing their breeding patterns just days before a magnitude 5.9 earthquake killed over 300 people in 2009. Perhaps these animal behaviours can be used to predict the occurrence of earthquakes, but without knowing the nature of the signals which trigger their response it has limited applications in disaster risk reduction.

Figure 1- Frogs on logs. It has been suggested that aquatic organisms such as these may be able to predict earthquakes from changes in groundwater chemistry. (Source: https://www.pexels.com)

The problem with focusing so much on anecdotal evidence is that the stories are often augmented by the human imagination, an effect often seen in the game ‘Chinese Whispers’.  The result is that the unusual behaviour apparently displayed by the animals before earthquakes occur can become exaggerated and, in many cases, the reports only appear after the earthquake has struck. It is very well announcing a pet’s unusual behaviour after the disaster, but had the earthquake not occurred would the behaviour still have stood out as being so strikingly abnormal?

Animal behaviour is extremely complex and using this as a metric for earthquake prediction is not considered to be feasible because of the inconsistency of animal responses. This has not prevented at least one Chinese city from installing 24-hour surveillance on a snake farm with the intention of detecting unusual behaviour for the purposes of earthquake prediction. In 1975 officials successfully evacuated a city of one million people just before a 7.3 magnitude earthquake in Haicheng, China, purportedly based on abnormal animal behaviour. However, this has been rejected as substantial evidence for the power of animal foresight as this earthquake was one which was preceded by a number of low magnitude foreshocks which are thought to have given the governing body of Haicheng the confidence to evacuate the city, under the impression that a larger earthquake was on its way.

Figure 2 – Aftermath of an earthquake in 1971, San Fernando, California. Source:  USGS
Denver Library Photographic Collection.

As is almost always the case, the evidence from a number of different studies is contradictory and inconclusive, implying that the predictive signals, if present, may vary between earthquakes. Evidence for the ability of animals to predict earthquakes was found in a study in Peru – no animal movement was recorded by camera traps on the rainforest floor (an extremely unusual observation) five out of the seven days leading up to the magnitude seven Contamana earthquake that affected the area in 2011. Other studies, however, such as those performed in the 1970s by USGS, have found no correlation between earthquakes and the agitation of animals.

The evidence is patchy, but if there truly is a relationship between animal behaviour and earthquakes the identity of the signal that the animals are responding to remains a mystery. A paper released in 2011 describes a mechanism by which stressed rocks could release charged particles. These particles could then react with groundwater, producing chemical signatures which may be detected by aquatic and burrowing life. Other suggestions of potential signals include ground tilting, although this would have to be present only at miniscule levels not to be detected by current technology, or variations in the Earth’s magnetic field.

Currently research into the use of animals in earthquake detection is being led by Japan and China, two countries regularly affected by earthquakes and where a plethora of anecdotes relating to the powers of earthquake prediction by animals have originated. While earthquake prediction could help to reduce the impact of earthquakes on society, there are far more effective and immediate things that we can do. Ensuring properly constructed buildings and enforcing building codes, tackling the underlying social vulnerability (e.g., poverty, inequality) and improving governance structures and earthquake education are some examples.

Read more about disaster risk reduction in the UN Sendai Framework for Disaster Risk Reduction.

Bárbara Zambelli Azevedo: Access​ ​to​ ​clean​ ​water,​ ​gender​ ​equality​ ​and​ ​geosciences

The importance of access to safe drinking water in our lives is quite obvious. Although its relation with gender equality and sustainable development may be less so. In this article, Bárbara Zambelli Azevedo explores the relationship between the two and discusses what geoscientists can do to improve the situation.

In 2017, according to the WHO, over 2.1 billion people still don’t have access to safely managed water (“safely managed drinking water means drinking water free of contamination that is available at home when needed”). It represents 3 out of 10 people worldwide! This number also includes 844 million people that don’t even have a basic drinking water service (more than Europe’s entire population), 263 million who have to spend over 30 minutes per trip outside their homes collecting water and 159 million who still drink untreated surface waters.

Daily collection of water in Tanzania (Credit: Joel Gill, distributed via imaggeo.egu.eu)

Target 6.1 of Sustainable Development Goal 6 states “by 2030, achieve universal and equitable access to safe and affordable drinking water for all”. Here is a map showing the progress of access to water from 1990 to 2017 and projections to 2030.

But how does the lack of access to water impact women’s lives? Around the world, in many societies, women and girls are more likely to be responsible for the collection and management of household water supply, sanitation and health. Water is not only used for drinking and cooking purposes but also for cleaning, laundry, personal hygiene, and care of domestic animals, among other uses. Because of their dependence on water resources, women are also unduly affected by water scarcity, climate change and disasters.

Groundwater in India

According to the World Bank, India uses approximately 230km³ per year of groundwater, being the largest user of groundwater worldwide. Over 85% of drinking water comes from groundwater sources.

This exploitation of groundwater is causing a scenario of scarcity of agricultural and drinking water, especially during drought years, in both Guajarat and Rajasthan watersheds. Those watersheds have hard rock aquifers, with low connectivity, limited storage capacity and large groundwater fluctuations. In Dharta watershed (Rajasthan), groundwater trends from the past 20 years are showing a net rate of groundwater depletion. A survey took place in eight secondary schools located in Rajasthan and Guajarat watersheds in semi-arid regions in India, relating groundwater scarcity to school absenteeism of female students. The main objective was to assess students’ perceptions of groundwater scarcity and their educational opportunities.

As a result, more than 90% of the students surveyed in both watersheds identified groundwater scarcity as a major issue. Around 95% reported that they are involved with housework aside from their studies. Usually, females are responsible for fetching drinking water, cooking, cleaning and taking care of their young siblings, while males helped with farming work. They associated directly their absenteeism from school to demand for home duties. In this sense, increasing groundwater scarcity is expected to intensify household chores, particularly on females to fetch water, who have to walk longer distances and spend more time executing this task. This may impact on inclusive educational opportunities for female students. Water scarcity was identified as being a primary factor influencing school attendance by 77% of female students who missed school.

What geoscientists can do?

Groundwater is a precious resource for communities, although optimising its potential can be difficult. Firstly, groundwater can not be found everywhere, which make drilling a risky business. Secondly, the quantity and quality of water that can be withdrawn in a borehole can vary just within a few meters.

Geoscientists can help by doing a good siting for a borehole, for example. This requires a professional with suitable training, experience of siting boreholes and knowledge of the best types of survey to carry out. This person can be a geologist, a hydrogeologist or an engineer with sufficient geoscience understanding. A consistent approach for well location involves identification of features on the ground that may be favourable for groundwater occurrence, selection of the most suitable geophysical method (if needed), data interpretation and stakeholder consultation. The dialogue with a community is important in terms of understanding where users would like boreholes to be. The (hydro)geologist need to point out contamination sources such as latrines, burial sites or other forms of pollution. They will also find out who owns the land and if it can be accessed by the community (read more). To know more about siting of drilled water wells, download this resource.

Borehole in Tanzania (Credit: Tumaini Fund)

Supply of clean water is fundamental for permitting women and girls to devote more time to the pursuit of education and income generation. Geoscience is fundamental to delivering SDG 6 (clean water) but also SDG 5 (gender equality).

Guest Blog: Anthropogenic climate change – what does this mean for groundwater resources in Africa?

Borehole in Tanzania (Credit: Tumaini Fund)

On the 25th October, Laura Hunt (Cardiff University) attended the joint meeting of the International Association of Hydrogeologists (IAH) and the Hydrogeological Group of the Geological Society, which included the Ineson Lecture at the Geological Society of London. 

It is a common misconception that Africa is an entirely dry, arid continent, parched for water. A resource that we in the UK take almost for granted, but that we assume all across Africa is hard to come by, with women walking many miles a day for drinking water, which is for the most part polluted with toxins and waterborne diseases. And for many communities, in many countries within Africa, this unfortunately is the case; the lack of surface water is a barrier to social and economic development.

But Africa is also a resource rich continent in terms of water. The continent has a huge groundwater resource, including large transnational aquifers. The exploitation of this incredible resource could be the key to facilitating Africa’s development, and coping with its rapidly increasing population.

Increasingly, investment in Africa’s water resources from NGOs, charities and private firms is in boreholes to extract clean groundwater. However, with anthropogenic driven climate change in this century and beyond predicted to be most adverse and rapid in the lowest (and highest) latitude regions, it’s important to understand the implication of a (overall) warmer and wetter world on this important resource prior to huge investment and increased dependency of many vulnerable countries upon it.

At the IAH conference, which I was lucky enough to attend with support from Geology for Global Development, University College London’s Richard Taylor spoke of his work aiming to answer this question with use of the ‘Chronicles Consortium’ – a collaboration of many groundwater resource’s multi-decadal hydrographs from a number of African countries to understand the response of aquifers to short term climatic events.

Africa is a vast continent with huge contrasts in climate between regions, and so climatic changes will not be unilateral across the continent, hence leading to different impacts on distant groundwater resources. The 2015/2016 El Nino event which was the second strongest event experienced for 150 years lead to contrasting impacts on the water balance across the continent. The Limpopo Basin (central southern Africa) experienced dry conditions, enhancing aridity in the area, whereas Northern Mozambique experienced wetter weather, with groundwater recharge recorded at 2000 boreholes.

The ENSO (El Nino Southern Osscilation) evidently had a strong influence upon groundwater recharge in some areas. In central Tanzania. Despite increased rates of pumping from the aquifers in the Makutapora basin (ie decline in water), ground water levels still rose.

The mechanism and conditions for recharge to occur is important in understanding the response of climatic change. Recharge velocities associated with the application of the regular diffuse model to recharge of the Makuapora Basin are simply inadequate to account for the rates of recharge recorded. However a mechanism of recharge focused pathways that focus diffuse recharge allow for faster infiltration and recharge of groundwater. These recharge pathways are the major, domain component of groundwater recharge as they are so focused compared to diffuse infiltration, but are only realised (utilised). Approximately 5-15mm of rain per day is required for 5-13 days are required for recharge to occur.

It can therefore be concluded that recharge occurs episodically and results disproportionately from heavy rainfall events.

So what are the implications of the changes in climate that we are already seeing and will continue into and beyond the 21st Century and beyond on these ground water resources? The key to sustainability is that development and investment should benefit future generations and so we need to make sure that this resource is viable for the future.

Firstly, climate change will lead to increased aridity around the equator, but enhanced rainfall around the tropics, creating disparity in the health of aquifers across the Africa.

Around the tropics, precipitation is expected to be less frequent but more intense, and so the threshold required for recharge is likely to be met, and so recharge will be greater (along with increased frequency of flooding events).

However, heavy rainfalls and increased macrogenic flow of water in the soil zone leads to greater contamination of shallow waters and are more vulnerable to pathogen transfer. Antecedant conditions also have a significant control over water quality with dry antecedent conditions leading to lower water quality with the highest degree of contaminiation than if antecedent conditions are wet. If climatic change causes more intense precipitation, and less gentle rainfall events, groundwater in regions of recharge are likely to become increasingly contaminated.

This research is just the beginning of understanding and predicting the response of the water table to climatic change, but allows us to begin to understand what challenges will be faced by Africa’s hydrogeologists and water authorities. This incredible resource with the power to drive Africa’s development, if chosen to be located in areas where overall long term recharge will occur, can be managed to reduce the effects of enhanced contamination and therefore provide a reliable and safe drinking water supply to some of the people most vulnerable to anthropogenic driven warming. With management of disease spread that was also showcased at the IAH conference by Cambridge University, it seems that there is the potential for a positive future for some African countries water resources to be revolutionised by the use of ground water. And this can be done sustainably – so long as the right long term management and planning, and of course further research is implemented.

This post is a guest contribution, sharing initial thoughts of a student attending the Ineson Lecture (and associated meeting) in London. For further information about the event, please see the event webpage and  contact the speakers directly.