Four Degrees

The wet with the dry: The geology of Siwa Oasis

Flo Bullough March 10, 2014

Flo takes us on a photoblog-trip to Siwa Oasis in Egypt where epic sand seas meet freshwater springs, saline lakes and sulphurous hot pools!

Siwa Oasis, adapted from Google Earth.

The blog’s going on holiday this week! I spent a week in Egypt on holiday last month and braved the 10 hour overnight bus journey from the capital city Cairo to visit the breathaking beauty of the Siwa Oasis in the Egyptian sand sea of the Libyan desert. I have to say that the shift from big-city Cairo to Siwa via a 10 hour bus drive added a real sense of remoteness when we pulled into the town, bleary-eyed the following morning.

Map of Egypt with the route from Cairo-Siwa, adapted from Google Maps.

I really didn’t know anything about Siwa at all before arriving there apart from noticing the numerous and ubiquitous boxes of Siwan bottled water around Cairo, not an industry I had associated with a small town in the middle of the desert. I’ve always thought of oases as being on a small scale and having a fabled quality and so suffice to say I wasn’t ready for the numerous lakes, springs and hot pools that abound in Siwa.

Siwa is an area of contrasts, the epic sand dunes visible to the west of town are juxtaposed with over a 1000 fizzing natural springs, sulphurous hot pools, and hypersaline lakes. It’s this unique collection of features that brought people to settle here over 12,000 years ago and continues to attract tourists, despite its remote location! And it is certainly bizarre to be in the middle of a desert and find that almost all the things to visit are water related.

History

Aside from the mind boggling landscape and geology, Siwa has an unusual and diverse history. It is one of Egypt’s most isolated settlements, both geographically and culturally with a population predominantly made up of ethnic Siwans who speak Siwi, a distinct language of the Berber family with a smaller proportion of Arabic-speaking Egyptians. Historically, Siwa is famous as the home of the Oracle of Amun and the ruins of this temple can still be visited today.

View of Siwa Landscape from the Temple of Amun – Authors own image.

It was here that Alexander the Great travelled (as well as founding Alexandria), during his campaign to conquer the Persian empire in 332 BC to consult the Oracle of Amun. There it is alleged the Oracle confirmed Alexander the Great as both a divine personage and the legitimate Pharoah of Egypt! The remoteness of the oasis meant that contact with the outside world was rare. The first record of a European visiting since roman times was the English traveler William George Browne who arrived in 1792 to see the ancient temple of the oracle. The oasis wasn’t even officially added to Egypt until 1819 and the first asphalt road to Siwa wasn’t built until the 1980’s! This isolation has served to preserve the delicate environmental and cultural balance of the Oasis. A small town of around ~23,000 people, Siwa’s economy is based on agriculture, largely olives and dates, some tourism and the water bottling plants dotted around the Oasis. But how did all this water come to be here? As with all things, we need to start with the geology!

Regional geology and geography

The area around Siwa is described as a ‘slightly undulating limestone plateau’ of Miocene age as the 1910 geological map of Egypt shows below and the vast areas of the map marked ‘Unexplored’ give you some insight as to how remote and difficult some of this terrain is.

1910 Geological Map of Egypt by the Survey Department of Egypt. Image out of Copyright.

Siwa sits in the Qattara depression which spans the north west of Egypt. Much of the depression sits below sea level: at its deepest it sits at 133m below sea level making it the second lowest point in Africa. It is bounded by steep slopes to the North side and to the south and west it grades into the Great Sand Sea.

Map of Egypt showing the location of the Qattara depression in blue – Source – Eric Gaba, Wikimedia Commons.

The depression is thought to be formed by the processes of salt weathering and wind erosion working together. The intense aelioan weathering causes the salt to crumble the depression floor and then the wind blows away the resulting sands.

Souvenirs made from salt-rock for sale in Siwa. Image Author’s own.

Salt is an issue in Siwa (although it makes for a modest market in selling bottled salt and also salt-rock souvenirs such as lamps). A number of fresh water springs that occur naturally in the Oasis run into salt water lakes making a lot of the water useless. Often even the spring water has an elevated level of salt and so not good for agriculture. This limits agricultural production in the area to mostly hardy crops such as dates and olives.

Just one of the 1000’s of springs in the Siwa area, this is ‘Cleopatra’s Pool’. The spring water here bubbles up from depth at pressure. Image Author’s own.

The main Oasis lakes Birket al-Maraqi and Birket Siwa are saline and no marine life survives. Indeed some of the water is so salty that you can see crystals growing in the water. The salty soil of the oasis continues to be used to build the traditional mudbrick houses which creates a problem. While the salt helps to strengthen the walls of the house, it also melts in the rain. And it doesn’t take much to destroy the houses, in 1928, a major storm resulted in the local inhabitants abandoning their ancient town including the ancient Shali Fort found in the centre of the town. These days new houses are prefabricated to remove the risk of rain melting the building materials!

Shali Fort in the centre of Siwa made from salty mud sourced from the oasis. You can see the damage sustained y the 1928 storm in the collapsing walls. Image Author’s own.

The Wet with the Dry

The Wet

With a mean annual precipitation of 8mm and many rainless years, the vast lakes in the region have something other than the weather to thank for their existence. The wide spanning Qattara depression contains a number of small basins on the floor which hold lakes. It is thought that these lakes were much larger during the Pleistocene Ice Age. It is at the fossil shorelines of these lakes that you can find the bounty of fossils we saw on our trip. These days the levels of the lakes fluctuate seasonally with some lakes drying up completely during the summer seasons.

The numerous springs supply that supply water to the lakes is thought to have been underground for 30,000-50,000 years in the Nubian Sandstone Aquifer System which is considered to be a non-renewable source of water in the North Africa area. It covers parts of Libya, Egypt, Sudan and Chad having a huge storage capacity of ~200,000 bcm of fresh water.

Hot sulphurous springs at Bir Wahed. Image Author’s own.

Whilst the features of Siwa Oasis are broadly natural phenomena there are some other beautiful water-related sites in the area which had a bit of a helping hand in their formation. Around 15km South-West of Siwa you come to the hot and cold springs of Bir Wahed. Both public bathing spots, the first is a sulphurous hot pool where you can relax under the desert sun, and the second is a large cold spring water lake. These two formed when a Russian or American ( depending on who you speak to) oil company came to do some prospective drilling in the 80’s. They didn’t find any oil but they did find water and their activity created the two mini-oases found there today. Now they serve as blissful tourist stops amid the dunes of the Great Sand Sea.

The cold spring lake at Bir Wahed, formed during prospective drilling for oil in the 80’s. Image Author’s own.

The Dry

Sand dunes in the Great Sand Sea. Image Author’s Own.

The Great Sand Sea seen to the West of Siwa Oasis is a 72,000 sq km behemoth of a desert (about the size of Ireland) and is made up predominantly of parallel seif dunes some over 100m high and over 150km long. The area has a rather morbid and adventurous past dating back 2,500 years ago when a 50,000 strong Persian army led by the Persian King Cambyses II is thought to have drowned in the sands of the western Egypt desert during a sandstorm. It was reported in 2012 that the remains of the army may have finally been found and thus solving one of archaeology’s biggest outstanding mysteries. Having spent the afternoon in the dunes, it’s wasn’t hard to see how you could lose your bearings without the aid of modern technology.

Great Sand Sea, Egypt. Image Author’s Own.

The landscape of the areas is mainly shaped by aeolian processes causing deflation hollows (where the force of the wind is concentrated on a particular spot in the landscape), erosion can carve out a pit knowns as a deflation hollow. They can range in size from a few metres to a hundred metres in diameter. Much larger, shallower depressions called pans can also form which cover thousands of square kilomeres. The Qattara depression is one of the largest pans in the world, while Siwa is a smaller pan. The Great Sand Sea wasn’t always a desert and large areas are thought to have been submerged underwater as attested to by the presense of rich fossil-bearing sediments outcropping in the desert. The fossil finds in this area include a whale skeleton, a human footprint, oysters and echinoids up to Miocene in age.

Fossils found exposed in the Great Sand Sea. Imasge Author’s Own.

Finding sea-living fossils in the desert reminded me of just how powerful geological understanding is. Standing looking out over the wind shaped dunes, it’s hard to imagine a thriving shallow sea existing here, but that it did and the deposits and fossils help us to observe and understand past environments, however different they may have been! Water Management

Groundwater Well in Siwa. Image Author’s Own.

Groundwater is the only source of water in Siwa which is used for home use as well as for agriculture and the local economy including the four companies that now bottle water in Siwa. For 1000’s of years the natural system was sustainably preserved but emerging pressures from development, tourism and climate change could put this delicate water system and the ecosystems it supports at risk.

Since the 1960s the Oasis has experienced significant changes in activity patterns which have had an impact on land use and water management. These days in drier parts of the year the Oasis lake is often dry leaving only mud flats behind due to local government irrigation practices siphoning water away from the lake.

The large size of the Qattara depression and the fact that it’s at a very low altitude has led to several proposals to create a massive hydroelectric project in northern Egypt rivalling the Aswan high dam. Interest in this has waned slightly in recent years but future stability in the country could create the climate for development and this would have significant impacts on the Siwa region.

The Water-Energy Nexus

Flo Bullough February 4, 2014

Tarbela Dam on the Indus river in pakistan. The dam was completed in 1974 and was designed to store water from the Indus River for irrigation, flood control, and the generation of hydroelectric power. The use of water for power captures the interdependence of energy and water. Source - Wikimedia Commons

Flo Bullough writes on the concept of the water-energy nexus; its implications for energy and water security and the impact of climate change and future planning and regulation.

I first came across the concept of the water-energy nexus when the former UK Chief Scientific Advisor John Beddington discussed the interdependence of food, water and energy as part of his tenure at government: something he described as a ‘perfect storm’. Since then, much has been written about this topic and below is an overview of the issues as they relate to the geosciences.

Tarbela Dam on the Indus river in pakistan. The dam was completed in 1974 and was designed to store water from the Indus River for irrigation, flood control, and the generation of hydroelectric power. The use of water for power captures the interdependence of energy and water. Source - Wikimedia Commons

Water stress and scarcity is one of the most urgent cross-cutting challenges facing the world today and is intrinsically linked with the need for energy. Water is required for extraction, transport and processing of fuel as well as to process fuels, for cooling in power plants and for irrigation in the case of biofuels. While energy is required for pumping, transportation and the purification of water, for desalination, and for wastewater. The interconnectedness is such that water and energy cannot be addressed as separate entities. This interdependence is termed the ‘water-energy nexus’, an approach which allows a more holistic assessment of energy and water security issues. Water scarcity is intensifying due to excessive withdrawal , whilst concern for energy provision is sparked by diminishing fossil fuel reserves and the built-in problem of CO2 emissions and climate change.

Over the last 50 years, the amount of water withdrawals has tripled while the amount of reliable supply has remained constant. This has resulted in depletion of long term water reservoirs and aquifers, most acutely in emerging economies with high population growth such as China, India and areas in the Middle East. Additionally, pressures such as the growing cost of fuel extraction, climate change and the of the energy mix has put pressure on the security of energy supply.

Map of the global distribution of economic and physical water scarcity as of 2006. Source – Wikimedia Commons

Energy limited by water

The energy sector relies heavily on the use and availability of water for many of its core processes. Resource exploitation, the transport of fuels, energy transformation and power plants account for around 35% of water use globally. Thermoelectric power plants are particularly thirsty and use significant amounts of water accounting for the majority of water use by the energy sector. In the USA in 2007, thermoelectric power generation, primarily comprising coal, natural gas and nuclear energy, generated 91% of the total electricity and the associated cooling systems account for 40% of USA freshwater withdrawals (King et al., 2008).

Of the different types of power plants, gas fired plants consume the least water per unit of energy produced, whereas coal powered plants consume roughly twice as much water, and nuclear plants two to three times as much. By contrast, wind and solar photovoltaic energy consume minimal water and are the most water-efficient forms of electricity production.

Comparative water consumption values by energy type. Data source – WssTP

There has been much discussion over the variable CO2 contributions of different fuels but these can be misleading, as the consideration of water consumption (as opposed to withdrawal, see Link) is often omitted. For example, unconventional fracked gas is often presented as a preferable source of energy over coal due to its reduced associated CO2 emissions, but the extraction of fracked gas consumes seven times more water than natural gas, oil extraction from oil sands requires up to 20 times more than conventional drilling and bio fuels can consume thousands times more water due to the need for irrigation. Additionally, carbon capture and storage (CCS) technology has the capacity to remove CO2 from the system but is also estimated to need 30-100% more water when added to a coal fired power plant. Looking at carbon intensity alone may result in a scenario where electricity production is constrained by water scarcity, while global demand for electricity increases.

Water limited by Energy

The flipside to the need for water for energy production is the need for energy in order to produce and deliver water for drinking and other domestic, agricultural and industrial use. Domestic water heating accounts for 3.6% of total USA

Water treatment works. Source – Wikimedia Commons

energy consumption (King et al., 2008) while supply and conveyance of water is also energy-intensive and is estimated to use over 3% of USA total electricity. Energy is required at every step of the supply chain, from pumping ground water (530 kW h M-1 for 120 m depth), to surface water treatment (the average plant uses 370 kWh M-1) and transport and home heating (King et al., 2008). Water treatment will require even more energy with the addition of treatment technologies and purification measures. Water companies in the UK report increases of over 60% in electricity usage since 1990 due to advanced water treatment and increased connection rates, and conservative estimates predict increases of a further 60-100% over 15 years in order to meet the myriad relevant EU directives. This increased energy use may result in displacement of the pollution problem from that in water bodies to build up of CO2 in the atmosphere.

Desalination

One of the most problematic developments in the competition for water and energy is the growth of desalination. It is used in areas suffering from water scarcity, but have viable energy sources to power the energy-intensive purification process. In areas such as the Middle East, the Mediterranean and Western USA, governments have increased their investment in desalination technology in order to secure a more stable water supply. However, the high-energy requirements, steep operational costs, wastewater disposal issues and large CO2 emissions often make this an unsustainable solution.

Desalination is often made economical through access to cheap, local energy sources and an abundant water source. This

Desalination can be very energy intensive. A view across a reverse osmosis desalination plant. Source – Wikimedia Commons

usually precludes the adoption of desalination in many land-locked countries, as operational costs increase with distance from the water source. However, increased water stress is leading to calls for more ambitious projects such as the planned Red Sea-Dead Sea project (see an earlier Four Degrees post on this) to build a desalination plant and a 180 km pipeline through Israel, Palestine and Jordan.

Desalination can use 10-12 times as much energy as standard drinking water treatment, and is expensive, unsustainable and can lead to increased CO2 emissions (King et al., 2008). These undesirable effects have led to widespread opposition to desalination in areas such as California and Chennai, India. Utilising renewable energy resources, coupled with the use of saline or wastewater for cooling at the power plants, could make the process more sustainable.Water and energy are set to become increasingly interdependent, and by 2050 water consumption to generate electricity is forecast to more than double.

The Impact of Water Scarcity

Freshwater scarcity is a growing issue and by 2030, demand is set to outstrip

India is a very green and wet country courtesy of its regular monsoons but poor management and overexploitation has left is with problems with water scarcity. Source - Wikimedia Commons

India is a very green and wet country courtesy of its regular monsoons but overexploitation of its water resources has left it with problems with water scarcity. Source – Wikimedia Commons

supply by 40%. This is due in part to economic and population growth, but also the rise of aspirational lifestyles, which creates demand for more water-intensive products. This increase in demand will put additional pressure onto water-stressed regions, as well as intensifying current trans-boundary water conflicts. The issue of water shortages often intersects geographically with fragile or weak governments and institutions that may lack the capacity to put in place measures to address water security. In 2004, 29% of India’s groundwater reserves resided in areas that were rated semi-critical to overexploited. About 60% of India’s existing and planned power plants are located in water-stressed areas and there are plans to build a further 59 GW of capacity, around 80% of which will be in areas of water stress and scarcity.

Click on the image to watch an animation showing the average yearly change in mass, in cm of water, during 2003-2010, over the Indian subcontinent. Source – Wikimedia Commons

Climate change impacts

Climate change presents a challenge to business-as-usual assumptions about future energy and water provision. Predicted major heat waves and droughts will add pressure to both water and energy security. Climate change is set to affect areas around the world in unprecedented ways; in southern Europe, temperatures are likely to rise, and drought will become more common in a region already vulnerable to water stress. Particularly in Spain, a country that derived 14.3% of its electricity production from hydropower in 2010, where hydroelectric plants have been under considerable stress in the last 20 years due to long running issues with drought (Perez et al., 2009; Trading Economics, 2013). Power cuts caused by extreme weather events, which are expected to become more frequent, will affect areas that rely heavily on energy-intensive ground water extraction for drinking water.

The 2013 EIA Energy Outlook up to 2040 shows steady increases in the need for all fuel types for energy use. Source – Wikimedia Commons

What can be done?

The conflict between more water-intensive energy production and the water needs of a growing population, seeking a better quality of life, will exacerbate an already stressed water-energy nexus.Additionally, Climate change is now considered an issue of national security in many countries, threatening both people and the environment within and across state boundaries. For this reason, climate change mitigation and adaptation must be managed at a new strategic level, beyond that of national law making. A more holistic approach to management of environmental change, water and energy security will also be required. It will also require strategic planning of water and energy security over much longer timescales than previously.New water and energy production plants must be sited with consideration for water withdrawal, consumption and local power accessibility in addition to future unpredictability in climate as the lifetime of such developments is several decades or more.

Regulatory Changes

Another important tool to address these issues is regulation. Current regulatory frameworks such as the European Climate and Energy Package and the Water Framework Directive (WFD) need to be developed in light of the water-energy nexus model. The EU is committed to 20-30% reduction in CO2 emissions by 2020 compared to levels in 1990, with reductions of up to 50% by 2030 and 80% by 2050 under negotiation. In contrast, the WFD requires additional treatment measures and this will need additional energy, exacerbating tensions between water and energy demand.

There are many policy instruments that can be used to regulate the role of water and energy management, such as water pricing and charges on carbon emissions to incentivise sustainable behaviour. A recent example of this includes the new US Environment Protection Agency announcement that they will be limiting greenhouse gas emissions for all new electricity generating power plants for coal and gas. The development of CCS technology could reduce the carbon footprint of power plants, but water consumption implications should be taken into consideration. Adoption of disincentives for certain types of land-use change and stricter building and engineering regulations could also be introduced to increase resilience against extreme weather.

The growing geopolitical issues of water location and scarcity will need to be managed through adaptable water sharing agreements, since many of the world’s largest and most important river basins, such as the Mekong River, which passes

Map of the Mekong River – The long and complicated route of the Mekong river and its intersection with many borders shows the complexity of water management. Source – Wikimedia Commons

through south-east Asia, cut across many borders. Co-management strategies such as shared water level and quality information will become important so as the water systems can be managed effectively. Governments must also improve their resilience to extreme weather conditions individually and collectively.

A greater focus on recycling energy- and water-intensive commodities would also alleviate water stresses when taken together with other measures. Education about recycling and water and energy conservation programmes could produce benefits, but also require investment and careful management.

This broad set of issues can only be effectively ameliorated through a holistic approach. A broad analytic framework is needed to evaluate the water-energy relationship, and this must be balanced with local policy contexts and different regulatory measures to ensure water and energy are sustainably managed in the 21st century.

A version of this post first appeared in the European Federation of Geologists magazine ‘European Geologist‘.

References and Further Reading

Gassert, F., Landis, M., Luck, M., Reig, P., Shiao, T. 2013. Aqueduct Global Maps 2.0. Aqueduct, World Resources Institute. (accessed here in March 2013: http://aqueduct.wri.org/publications)

Glassman, D., Wucker, M., Isaacman, T., Champilou, C. 2011. The Water-Energy Nexus: Adding Water to the Energy Agenda. A World Policy Paper. (accessed here in March 2013: http://www.worldpolicy.org/policy-paper/2011/03/18/water-energy-nexus)

IEA World Energy Outlook 2011. (accessed here in March 2013: http://www.iea.org/newsroomandevents/speeches/AmbJonesDeloitteConference21MayNN.pdf)

King, C, W., Holman, A, S., Webber, M, E. 2008. Thirst for energy. Nature Geoscience, 1, 283-286.

Lee, B., Preston, F., Kooroshy, J., Bailey, R., Lahn, G. 2012. Resources Futures. Chatham House. (accessed here in March 2013: http://www.chathamhouse.org/publications/papers/view/187947)

Perez Perez, L., Barreiro-Hurle, J. 2009. Assessing the socio-economic impacts of drought in the Ebro River Basin. Spanish Journal of Agricultural Research, 7, No 2, 269-280.

Trading Economics. Electricity Production from Hydroelectric Sources (%of total) in Spain. (accessed here in March 2013: http://www.tradingeconomics.com/spain/electricity-production-from-hydroelectric-sources-percent-of-total-wb-data.html)

WssTP The European Water Platform. 2011. Water and Energy: Strategic vision and research needs. (accessed here in March 2013: http://www.wsstp.eu/content/default.asp?PageId=750&LanguageId=0)

Radioactive waters

Marion Ferrat November 25, 2013

As the decommissioning of the damaged Fukushima nuclear power station begins, Marion Ferrat takes a look at how radioactive elements make their way to the world’s oceans – and how scientists can use them to study important processes that go on in our waters.

Fukushima Dai-ichi nuclear station – Source: Asacyan, Wikimedia Commons.

Early last week, work began to remove spent fuel rods at the disused Fukushima Dai-ichi power station, more than two years after the plant suffered a triple meltdown caused by the powerful earthquake and tsunami of March 2011. Over 1,500 fuel assemblies will be removed over the course of one year, but decommissioning of the entire site will take decades.

Like Chernobyl before it, the Fukushima disaster released large amounts of radioactive elements to the environment, many of which made their way into natural waters.

But such accidents are not the only sources of anthropogenic radionuclides – the radioactive products of nuclear reactions – to the environment. Radioactive elements have also been released from nuclear reprocessing plants, as well as from the hundreds of nuclear tests that took place between the 1940s and 1980s.

In this post, I want to explore what happens to these radioactive elements when they enter the aqueous environment, and how oceanographers use them as unique tracers to study ocean circulation patterns.

Where does the radioactivity come from?

The main sources of anthropogenic radionuclides to natural waters are:

Nuclear weapons tests in the 1940s-1980s:
This is what is called global nuclear fallout. Radioactive elements released during the hundreds of cold war weapons tests fell back into the oceans after the detonation of the nuclear devices. As most of the tests were carried out in the Pacific, this ocean became the largest repository of radioactive fallout. Only the longer-lived isotopes released from these tests remain in the environment today.

Radionuclides released during the Chernobyl reactor accident (April 1986):
The accident released 400 times more radioactive material than the Hiroshima bomb and is considered the worst nuclear accident in history. Adjacent regions in Belarus, Ukraine and Russia were the worst hit but a radioactive cloud travelling westward also contaminated many regions of Europe, the North Sea and the North Atlantic Ocean.

The Japan earthquake of 11 March 2011 – Source: Maximilian Dörrbecker, Wikimedia Commons.

Radionuclides released from the Fukushima Dai-ichi power plant (March 2011):
The tsunami generated by the Tōhoku earthquake of 11 March 2011 damaged the Fukushima nuclear facility, leading to equipment failure and a subsequent nuclear meltdown. This accident released between 10-30% of the radiation caused by Chernobyl. Fukushima and Chernobyl are both classified as level 7 (the maximum level) in the International Nuclear Event Scale.

Discharges from nuclear fuel reprocessing facilities:
Nuclear reprocessing plants involve the extraction of plutonium and uranium from used nuclear fuels. The chemical processes involved generate large quantities of waste, which makes its way into the environment. Authorised releases from facilities such as Sellafield in Cumbria and Cap de la Hague in France have contributed to the contamination of the Atlantic Ocean and Irish Sea. Though discharges have been heavily reduced since their peak in the 1970s and 80s, these can still be observed in the environment. The Centre for Environment, Fisheries and Aquaculture science (CEFAS) releases annual or multi-annual environmental monitoring reports assessing the impact of this contamination in Britain.

Aerial view the Sellafield nuclear reprocessing plant in Cumbria – Source: Simon Ledingham, Wikimedia Commons.

What are the main radionuclides in waters today?

A whole range of radioactive elements are released from these different sources. While some radionuclides produced are very short-lived (they decay with half-lives of hours to days), others can remain in the environment for tens to tens of thousands of years.

The main radioactive isotopes from these sources found in the oceans today include tritium (3-H), radiocarbon (14-C) and isotopes of strontium (90-Sr), technetium (99-Tc), caesium (134-Cs and 137-Cs) and plutonium (239-Pu and 240-Pu). They have half-lives ranging from 2 to 200,000 years.

These radionuclides are the most commonly studied both for monitoring (because of their radiological impacts) and research purposes: as it turns out, radioactive waters have a lot to say about the ways our oceans work.

Anthropogenic radionuclides: fingerprinting the oceans

Anthropogenic radionuclides are very strong tracers of oceanic, biogeochemical and sedimentary processes.

Once they make their way to the waters, they don’t just sit there; they swim, they sink, and they behave in a variety of different ways. Because some of these radioactive isotopes were absent from the natural environment until the mid 20^th century, they only have a relatively small number of possible sources and can act like “fingerprints”, pinpointing the movement of particular water currents. So scientists can sample ocean water on large research ships, look at radionuclide concentrations in the water today, and see how far they have moved around in the oceans.

There are two types of interesting radionuclides: those that dissolve in the water, such as tritium or caesium, and those that react with particles, like plutonium. These two types of behaviour allow oceanographers to study different oceanic processes.

The Pacific Ocean – Source: NASA, Wikimedia Commons.

Soluble radionuclides are useful because they get transported with water masses: where the water goes, the radioactive element follows. Because scientists know with relatively high confidence where the elements entered the water, they can look at how ocean circulation has re-distributed them worldwide. For example, high caesium concentrations were recently found in the Tasman Sea. These must have come from elsewhere as very few nuclear tests were carried out in the Southern Hemisphere. Scientists were able to trace this caesium back to its source in the North Pacific Ocean, allowing them to study in detail the way that Pacific waters get transported across the equator over decades.

Particle-reactive elements like plutonium are equally useful. They will tend to attach themselves to larger particles (what is called being scavenged) rather than dissolve in the water, so they will slowly sink to the bottom of the ocean along their transport route. A few years ago, scientists from the Marine Environmental Laboratories of the International Atomic Energy Agency in Monaco carried out a global study of plutonium in the oceans of the southern hemisphere. They found that plutonium from the North Pacific region had made its way to the South Pacific, through to the Indian Ocean, and onto the South Atlantic. They also noticed lower and lower concentrations in the surface waters along the way, so they were able to study both the exact route of water transport, and the rate at which particles in the ocean scavenged this plutonium.

Gallons and gallons of water

Though these radioactive elements are clearly present in the waters, their concentrations once they have travelled the world can be extremely low. This is a challenge for oceanographers wanting to measure them, because instruments cannot detect radioactivity below a certain level and measurements can be hampered by other sources of radiation. So scientists need to sample enough water to be able to confidently determine the radioactivity of their target radionuclides.

A rosette system for sampling seawater from research vessels – Source: NOAA Photo Library, Wikimedia Commons.

For tritium, this is relatively straightforward as it is present in high enough concentrations (but with little radiological impact). Approximately 1L of water is sufficient to determine its activity. But other radionuclides, such as technetium or caesium, have typically required up to hundreds of litres of water for one sample. This, of course, is problematic when sampling on a research ship: space is quickly taken up by huge containers of sampled water, and all of this water gets very heavy! Until recently, sampling ships have had to restrict themselves to certain elements or to a small sampling area in order to cope with the large volumes of water required.

Recent developments have allowed scientists to get around some of these problems. Radionuclides can be pre-concentrated on board the ship with clever feats of chemistry: the sampled water is passed through pumping systems containing certain reagents that ‘fix’ the radionuclide of interest (for example caesium), removing it from the bulk of the water. Once this is done, the remaining water can be emptied back into the ocean.

Developments in detector efficiencies and new ‘radiation-proof’ underground laboratories have also substantially increased the sensitivity of instruments and allowed the determination of important radionuclides in samples of tens rather than hundreds of litres.

Most of these radionuclides entered the oceans nearly half a century ago (this interesting video gives an idea of the scale of cold war nuclear testing over the Pacific Ocean). They will continue to decay with time and some will eventually disappear in a few decades. The longer-lived isotopes, however, will continue to swim the oceans for thousands of years to come. In any case, scientists will be able to use these nuclear products to study the world’s oceans.

Raising the Dead Sea

Flo Bullough November 8, 2013

The Dead Sea is one of the planet’s truly otherworldly places: a peculiarity of water distribution, climate and altitude, it is even more extroadinary in that it is a site of religious, cultural and political significance. Viewed by many as a natural wonder, its characteristics and location within one of the most entrenched political situations in modern history makes it intriguing and troubled in equal measure.

The Dead Sea is the deepest hypersaline lake in the world, situated at the lowest point on earth. It has a salinity of 33.7% due to high concentrations of NaCl and other mineral salts. The Dead Sea, aside from being a misnomer (it is actually an inland lake) is so-called because of the harsh living conditions that the salinity engenders. Many organisms such as fish cannot live there, in fact only populations of bacteria and microbial fungi can thrive.

The Jordan River. Source

Located in the Jordan rift valley bordering Jordan to the east, and Israel and Palestine to the west, it is served only by the Jordan River to the North. A combination of the mineral content of the water, low content of pollens, the reduced ultraviolet component of solar radiation and the higher atmospheric pressure at this depth have specific health effects which have borne a booming spa-tourism economy. This along with the dramatic scenery and tranquil waters is why it has long been a site of tourism and refuge; King David used it as such and it was one of the world’s first health resorts for Herod the Great.

There are two schools of thought as to how it formed; one is that the depression forms part of the East African rift valley complex and, another more recent hypothesis describes the formation as a ‘step over’ discontinuity along the Dead Sea Transform creating an extension of the crust. The sea was once connected to the Mediterranean and experienced regular flooding, resulting in thick layers of salt deposition. The land between the Mediterranean and the Dead Sea subsequently rose to cut the basin off and create a lake.

What’s the status now?

The dwindling water level of the Dead Sea. Source

The Dead Sea in more recent years has been characterised by a decline in water levels, a drop of ~30m since 1960 alone and is currently shrinking by around 1m/year. This is in part due to a drop in rainfall and the use of water upstream of the Jordan river for irrigation projects. Declining water levels have resulted in a wide variety of environmental issues for the Dead Sea ecosystems and surrounding region. One such issue is the ever-feared rumble that precedes the formation of sinkholes; these can be unpredictable and can occur suddenly almost anywhere in the Dead Sea region. Indeed, the level of uncertainty and rapidity of sinkhole formation is such that around 10 years ago, renowned geographer-geologist and expert on sinkhole phenomena Eli Raz was swallowed up by one and waited 14 hours for rescue!

Sinkholes in the Dead Sea area are caused by the interaction of incoming freshwater with subterranean salt layers. As the sea level drops, high levels of salt are left behind in the soil and when freshwater washes in from the Jordan River it dissolves the salts and cavities are created. This process continues until the subterranean structure loses integrity and sinkholes are formed. It is estimated there are now about 3000 in the region of the dead sea with an opening up of around 1 a day.

800px-Dead_Sea_sinkhole_by_David_Shankbone

Sinkholes along the shore of the Dead Sea. Source.

Why is the water level dropping?

Jordan, Syria, Palestine and Lebanon have all tapped the Jordan river for water over the last few decades for irrigation purposes resulting in a reduced flow into the Dead Sea. An area with historically low rainfall, ~ 2 inches a year, enormous amounts of water is also piped off to fill evaporation pools for the potash and magnesium industries which sit at the very southern end of the sea. This alone is thought to result in a 30-40% reduction in water.

In the last 50 years, the population in the surrounding countries of Israel, Palestine and Jordan has increased from 5.3 million to over 20 million with an increase in the settled population in the Dead Sea region. Currently, tens of thousands of tourists visit every year to bathe in the sea and use the many resorts and spas found along the shores and visit the mighty ruin of Masada (including me!) that overlooks the Dead Sea. Tourism is growing in this area and makes up about 40 percent of the income of local residents and this is putting further pressure on diminishing water resources.

The_Dead_Sea_1972-2011_-_NASA_Earth_Observatory

Views of the Dead Sea in 1972, 1989, and 2011 compared. Source.

How can environmental catastrophe be avoided?

The delicate balance of inflows, outflows, evaporation and rainfall has been severely disturbed in the last 50 years, and this hasn’t gone unnoticed. A highly ambitious project is underway to replenish the Dead Sea and ameliorate some of the water and energy shortage issues in the region. The World Bank, together with the local governments is planning to create a canal linking the Red Sea to the Dead sea. The project includes a series of studies including feasibility, environmental and social assessment with the aim of generating a trilateral agreement between Palestine, Jordan and Israel. If the plan goes ahead as detailed, the pipeline will deliver 2 billion cubic metres of sea water per year from the Gulf of Aqaba through Jordanian territory and to the Dead Sea. The plan is to also use the downwards flow between the Red Sea and the Dead sea to incorporate a hydroelectric plant. This is in turn will power a desalination plant which would provide up to 850 million m3 of fresh water per year to a water parched region. The briny discharge from the desalination plant would then be discharged into an already-saline Dead Sea. The project is likely to cost at least US $10 billion, a significant proportion of this is taken up by the cost to pump the desalinated water 200km over an altitude change of 1000m from the Dead sea towards Amman, an extremely parched area.

Algal Blooms in the Arabian Sea. Source.

So, it sounds good but is it really that simple? Many studies find that if more than 400 million m3 of sea water is added to the Dead Sea, this could result in the formation of algal bloom and unsightly gypsum crystals, the effects of which have effects that are difficult to predict, this will impact on the image and chemistry of the Dead Sea. Although the ecological effects of these chemical changes are still unclear, they would likely diminish the sea’s tourist appeal. This is in addition to the fact that the amount of water supplied would not be enough to stabilise or increase the level of the Dead Sea. There is also concern about the effects of mixing Red Sea water with Dead Sea water. Many other alternatives have been mooted by environmental groups, such as water recycling and conservation by Israel and Jordan, importing water from Turkey and desalinating sea water on the Mediterranean coast. Whilst pumping desalinated sea water from the Mediterranean to Ammam would be easier and cheaper, the geopolitics are concerning. Many worry that Israel would control the supply to Ammam. Another very real concern is the high frequency of earthquakes in the region, seismic activity could cause salt water to leak into underground fresh water aquifers. Others would prefer to see the rehabilitation of the Jordan River with a greater utilisation of desalination to provide water to the Mediterranean coast. All of these alternatives however require cooperation and a regional approach to water sharing which is difficult in this part of the world to say the least.

Regional Water Security

This issue sits within a wider problem. This is a region with extremely low levels of rainfall and a booming population. Jordan are well behind the Red-Sea-Dead-Sea project largely because the country’s access to fresh water is extremely restricted, which has been exacerbated by the arrival of more than a quarter of a million Syrian refugees since the outbreak of the civil war.

Nitzana desalination plant in Israel. Source.

Israel has long had issues with water scarcity. Due to low rainfall and a booming industry, the demand on water outstrips conventional water resources. This is put under further strain from the water-intensive agricultural practices used throughout the country.This is in part alleviated by their technologically advanced desalination plants dotted along the Mediterranean coast.

Gaza, on the Mediterranean coast is thought to be heading for a serious water crisis in the coming decade with 90-95% of the main aquifer contaminated, the UN suggest the water might be unusable by 2016. Meanwhile water shortages in the West Bank affect the provision of drinking water, water used for farming and agriculture in addition to that required for basic sanitation.

Regional Geopolitics

The regional geopolitics is intensely complex with many historic and current political factors at play. Others can write much more authoritatively on the area but it is worth mentioning here because, as with many geological issues, the interplay between the two is important.

The main regional players are Israel, Palestine and Jordan. Jordan, with few freshwater resources and no oil to power desalination plants, has long been considering an engineered solution to alleviate the water issue in Jordan. At peace with Israel since the signing of a treaty in 1994, the Jordanian government is hoping the plan goes ahead in full.

Israel and Palestine are significantly more complicated. The current de facto borders of Israel and Palestine are broadly along the lines drawn following the ‘Six Day War’ in 1967, as seen in the image, where Israel extended its borders and captured, among other territories, the West Bank.

Map of the West Bank and Gaza Strip. Source.

Contemporary Palestine now exists as two non-coterminous territories: the Gaza strip, which is on the Mediterranean coast (run by Hamas) and whose borders are controlled by Israel and Egypt, and the West Bank (the name of which refers to the Jordan River) which borders Israel to the north, south and west, and Jordan to the east. Civil and military authority in the West Bank is a mixture of the Fatah-led Palestinian Authority and the Israeli state. The Dead Sea spans the south east corner of the West Bank, as well as parts of Israel and Jordan. Whilst the West Bank shares a geographical border with Jordan, this is controlled by Israel, and the West Bank remains under Israeli occupation under international law.

In a region with scarce water resources, distribution can be controversial – and Israel’s monopoly over a shared aquifer and access to the Jordan River has resulted in the state being accused of restricting access to water for Palestinians.

Palestine (despite divisions in governance across the two territories) is still seeking independent statehood, and in 2012 was recognised at the United Nations as a ‘Non-member observer state’. As such, negotiations over multilateral initiatives such as the Red Sea-Dead Sea project have enormous geopolitical implications.

Other Cross-boundary Water Conflicts

There are many examples of delicate border regions which cut across natural river systems, such is the nature of modern national borders, they very rarely follow catchment areas and as such control over and use of water bodies can be highly contested.

Cross boundary water engineering negotiation goes on in many areas around the world and these often intersect with political and environmental issues. In addition to the Dead sea and Jordan river the Nile is subject to boundary issues, running through Egypt, Sudan and Ethiopia. Egypt and Ethiopia are currently negotiating over a billion dollar dam project being built in Ethiopia. Egypt are looking to help with the construction of the dam project.

The Caspian Sea has also had more than its fare share of water-rights disputes. A massive sea in Central Asia, its issues descend from the break up of the Soviet Union in 1991 and thus increasing the number of countries with an interest. As such a number of plans have been proposed and rejected due to lack of unanimity leaving the legality and governance of the area up in the air and resulting in resource grabs and export of resources struck without agency.

As with the Dead Sea, these examples show the great complexity in dealing with cross-boundary water management and no situation is the same, and must be dealt with carefully and on a case by case basis.

Flo

Further Reading

BBC News – Project to replenish Dead Sea water levels confirmed

Phys Org – Dead Sea, Red Sea plan raises environmental hackles

Nature – Environmental concerns reach fever pitch over plan to link Red Sea to Dead Sea

Slate – The Dead Sea is Dying