New method for detecting water on Mars

Washington State University senior Kellie Wall has helped develop a new method for detecting water on Mars. Her findings appear in Nature Communications, one of the most influential general science journals. Credit: Washington State University photo

A Washington State University undergraduate has helped develop a new method for detecting water on Mars.  

Kellie Wall, 21, of Port Orchard, Wash., looked for evidence that water influenced crystal formation in basalt, the dark volcanic rock that covers most of eastern Washington and Oregon. She then compared this with volcanic rock observations made by the rover Curiosity on Mars' Gale Crater.

"This is really cool because it could potentially be useful for not only the study of rocks on Earth but on Mars and other planets," said Wall.

She is the lead author of the article in Nature Communications.  

Co-authors include Michael Rowe, a former WSU research professor now at New Zealand's University of Auckland, and Ben Ellis, a former WSU post-doctoral researcher now at the Institute of Geochemistry and Petrology in Zurich, Switzerland. The other authors are Mariek Schmidt of Brock University in Canada and Jennifer Eccles of the University of Auckland.

Wall was fascinated by volcanoes as a child, touring the Cascade mountain range with her father and marveling at features like the lava tubes under Mount St. Helens.

"I was really excited because I thought that just on the other side of the walls there could be lava," she said.

Still, she started out as a communications major at WSU, choosing a geology class to fulfill a science requirement.

"I loved it so much that I changed my major," she said.

In her sophomore year, Rowe and Ellis asked if she would like to look at the eruption styles of Earth and Mars volcanoes.

"I was really crazy about it -- really intrigued by the buzzword 'Mars,'" she said.

"I've worked with a lot of undergraduate researchers over the years and she's the best that I've come across," said Rowe. "That's why we gave her so much responsibility on this project, because we knew she would do it well."

The researchers established a method to quantify the texture of volcanic rock using an index called "groundmass crystallinity." Wall compares it to the texture of a chocolate chip cookie, which can vary according to how it is cooked and cooled.

"We were interested in the cookie dough part of the cookie," she said.

Liquid volcanic rock cools rapidly as it hits water, flash-freezing to form mostly glass. Without water, it takes longer to cool and forms crystals within the groundmass, the cookie dough part.

Using an x-ray diffraction machine on the WSU campus, home to one of the most sophisticated basalt labs in the world, Wall analyzed rock samples from the Northwest, New Zealand and Italy's Mount Etna and compared them to rocks analyzed by Curiosity's x-ray diffractometer.

"The rocks that erupted and interacted with water, which we call phreatomagmatic, all had a groundmass crystallinity as low as 8 percent and ranging up to about 35 percent," she said. 

"The rocks that erupted without interaction with water had groundmass crystallinities from about 45 percent upwards to almost totally crystalline.

"The analyses we did on the Mars soil samples fell in the range of the magmatic type eruptions, which are the ones erupted without water interaction," she said.

Water is a key indicator for the potential of microbial life on the red planet. While Wall and her colleagues didn't see evidence of it from two sites they studied, their method could look for water elsewhere.

"I think this quantification of volcanic textures is a new facet of the water story that hasn't yet been explored," Wall said. "Most of the studies searching for water have focused on either looking for sedimentary structures -- large- and small-scale -- for evidence of water, or looking for rocks like limestones that actually would have formed in a water-rich environment.

"But being able to determine the environment through the texture of a volcanic rock is something pretty cool and different," she said. "I think it's an interesting avenue for future research."

Source: Washington State University

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Managing coasts under threat from climate change, sea-level rise

Sea levels are rising. Experts say that we need to address human-led and other non-climatic changes. Credit: Image courtesy of University of Southampton

Coastal regions under threat from climate change and sea-level rise need to tackle the more immediate threats of human-led and other non-climatic changes, according to a team of international scientists.

The team of 27 scientists from five continents, led by Dr Sally Brown at the University of Southampton, reviewed 24 years of Intergovernmental Panel on Climate Change (IPCC) assessments (the fifth and latest set being published in 2013 and 2014). They focused on climate change and sea-level rise impacts in the coastal zone, and examined ways of how to better manage and cope with climate change.

They found that to better understand climate change and its impacts, scientists need to adopt an integrated approach into how coasts are changing. This involves recognising other causes of change, such as population growth, economic development and changes in biodiversity. Dr Brown emphasised that: "Over the last two and half decades, our scientific understanding of climate change and sea-level rise, and how it will affect coastal zones has greatly increased. We now recognise that we need to analyse all parts of our human and natural environments to understand how climate change will affect the world."

The scientists also acknowledged that long-term adaptation to climate change can greatly reduce impacts, but further research and evaluation is required to realise the potential of adaptation. "Many parts of the coast can, with forward planning, adapt to sea-level rise, but we need to better understand environments that will struggle to adapt, such as developing countries with large low-lying river deltas sensitive to salinisation, or coral reefs and particularly small, remote islands or poorer communities," said Dr Brown.

For example, in the Maldives, many small, remote low-lying islands are at risk from climate change and will struggle to adapt. But around the densely populated capital city and airport, adaptation has already occurred as land claim is a common practice in order to relive population pressure. Sea-level rise has already been considered into newly claimed land. 

Thus in decades to come, potential climate change impacts, such as flooding, will be reduced for this island, benefiting both the local population and economy.

Dr Jochen Hinkel from Global Climate Forum in Germany, who is a co-author of this paper and a Lead Author of the coastal chapter for the 2014 IPCC Assessment Report added: "The IPCC has done a great job in bringing together knowledge on climate change, sea-level rise and is potential impacts but now needs to complement this work with a solution-oriented perspective focusing on overcoming barriers to adaptation, mobilising resources, empowering people and discovering opportunities for strengthening coastal resilience in the context of both climate change as well as existing coastal challenges and other issues."

This new research, published as a commentary in Nature Climate Change, will help in the understanding of the impacts of climate change and how to reduce impacts via adaptation. Its multi-disciplinary approach could be useful if future IPCC assessment reports are commissioned.

Source: University of Southampton

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Deforestation threatens species richness in streams

In the catchment area of the river Yangtzekiang in Southern China deforestation takes place in order to gain arable land and build tea plantations. Credit: © M. Kuemmerlen

With a population of 1.3 billion, China is under immense pressure to convert suitable areas into arable land in order to ensure a continued food supply for its people. Accordingly, China is among the top countries in the world in terms of the extent and intensity of land use change. As shown in a new study by a team of scientists led by Dr. Britta Schmalz (Kiel University), in cooperation with Dr. Mathias Kuemmerlen, LOEWE Biodiversity and Climate Research Centre (BiK-F) and Dr. Sonja Jähnig, Leibniz-Institute for Freshwater Ecology and Inland Fisheries (IGB), deforestation may change the water surface runoff conditions, leading to a negative impact on the occurrence of microorganisms in rivers and streams.

Studies in a sub-basin of China's longest river

As part of this study, funded by the German Research Association (DFG), the team examined an area of about 1,700 square kilometers located in the Yangtzekiang River watershed, namely a tributary of the Poyang lake in Southern China. By using an ecohydrological model, it was possible to show how different land use types and intensity levels can influence the hydrological regime. The five scenarios that were studied encompassed three different deforestation and two afforestation scenarios. A medium deforestation rate, in which 53 percent of the forest is preserved (of the original 70 percent) and the remainder is used as agricultural land and for tea plantations, most closely approximates the ongoing expansion rate of agricultural areas in this Chinese region. This scenario was used to model the potential impact of these changes on the distribution of 72 species of invertebrates, known as stream macroinvertebrates.

Considerable range decreases for freshwater biota

Species rich stream reaches could become less frequent as a consequence of deforestation. Especially in areas where land use changes are expected to be most severe, is where insect larvae, snails, worms and leeches might become endangered. "As an example, we highlighted the distribution range of the stonefly Topoperla sp., based on a moderate rate of deforestation. As a result of the projected changes, its distribution range would decrease to a mere 15 percent of its current range," explains Mathias Kuemmerlen, BiK-F. Topoperla sp., as many other invertebrate microorganisms, is regarded as a water quality indicator. This leads to the conclusion that deforestation has a negative impact on the overall water quality.

Conversion to arable land changes the hydrological regime

In the present study, the cause for the decrease in species diversity is the changing hydrological regime resulting from the conversion of forest to arable land. According to the study, increasing deforestation causes, increased surface runoff, especially during the rainy season, which later flows on into streams and rivers. "In forested areas, surface water drains more slowly and in lower quantities; a significant percentage of the rain water is absorbed by the soil and by trees. Higher runoff rates may only be seen in floodplain forests, if at all. If forests are cut down and converted into fields, the surface runoff increases." says Kuemmerlen. If areas are afforested, the opposite trend occurs, allowing soils to store larger amounts of water again.

Land use change should be sustainable

The research team points out that the study's results offer a scientific basis for a sustainable landscape planning and management which takes into account the water cycle of the respective regions. The ultimate goal should be to use the limited resource "land" in a way that it ensures food security. . However, there must be room for the necessary adaptation measures in the face of global climate change. To certain degree this is supported by the preservation of forests in their role as runoff regulators and water reservoirs. Further modeling studies are being carried out elsewhere, also in Germany, in order to continue improving our knowledge on similar processes.

Source: Senckenberg Research Institute and Natural History Museum

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Another human footprint in the ocean: Rising anthropogenic nitrate levels in North Pacific Ocean

Hawaii Ocean Time-series Program scientists work aboard the R/V Ka'imikai-O-Kanaloa in the North Pacific Ocean. The HOT Program provided decades of data used to reconstruct historical nitrogen concentrations.
Credit: Paul Lethaby, UH SOEST

Human-induced changes to Earth's carbon cycle -- for example, rising atmospheric carbon dioxide and ocean acidification -- have been observed for decades. However, a study published this week in Science showed human activities, in particular industrial and agricultural processes, have also had significant impacts on the upper ocean nitrogen cycle.

The rate of deposition of reactive nitrogen (i.e., nitrogen oxides from fossil fuel burning and ammonia compounds from fertilizer use) from the atmosphere to the open ocean has more than doubled globally over the last 100 years. This anthropogenic addition of nitrogen has reached a magnitude comparable to about half of global ocean nitrogen fixation (the natural process by which atmospheric nitrogen gas becomes a useful nutrient for organisms). David Karl, Professor of Oceanography and Director of the Daniel K. Inouye Center for Microbial Oceanography at the University of Hawai'i, teamed up with researchers from Korea, Switzerland and the U.S. National Oceanic and Atmospheric Administration to assess changes in nitrate concentration between the 1960s and 2000s across the open North Pacific Ocean.

Their analysis, which could discern human-derived nitrogen from natural nitrogen fixation, revealed that the oceanic nitrate concentration increased significantly over the last 30 years in surface waters of the North Pacific due largely to the enhanced deposition of nitrogen from the atmosphere.

"This is a sobering result, one that I would not have predicted," said Karl. "The North Pacific is so vast it is hard to imagine that humans could impact the natural nitrogen cycle."

The researchers used ocean data in conjunction with the state-of-the-art Earth System Model to reconstruct the history of the oceanic nitrate concentration and make predictions about the future state of the North Pacific Ocean. Their assessment revealed a consistent picture of increasing nitrate concentrations, the magnitude and pattern of which can only be explained by the observed increase in atmospheric nitrogen deposition.

Enhanced nitrogen deposition has several potential ecological ramifications. Because biological activity is limited by nitrate availability in the North Pacific Ocean, the input of new nitrogen from the atmosphere may increase photosysnthesis in the sunlit layers and export of carbon-rich organic material out of the surface ocean into the deep.

"The burgeoning human population needs energy and food -- unfortunately, nitrogen pollution is an unintended consequence and not even the open ocean is immune from our daily industrial activities," said Karl.

Given the likelihood that the magnitude of atmospheric nitrogen deposition will continue to increase in the future, the North Pacific Ocean could rapidly switch to having surplus nitrate. Thus, past and future increases in atmospheric nitrogen deposition have the potential to alter the base of the marine food web; and, in the long term, the structure of the ecosystem.

In particular, the shift in nutrient availability could favor marine organisms that thrive under the high nitrate and low phosphorus conditions. If similar trends are confirmed in the Atlantic and Indian Oceans, it would constitute another example of a global-scale alteration of Earth system. Further, the findings of this study of the North Pacific highlight the need for greater controls on the emission of nitrogen compounds during combustion and agricultural processes.

Source: University of Hawaii at Manoa

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Water’s role in the rise and fall of the Roman Empire

Roman aqueduct of Luynes. Credit: Daniel Jolivet

Smart agricultural practices and an extensive grain-trade network enabled the Romans to thrive in the water-limited environment of the Mediterranean, a new study shows. But the stable food supply brought about by these measures promoted population growth and urbanisation, pushing the Empire closer to the limits of its food resources. The research, by an international team of hydrologists and Roman historians, is published today in Hydrology and Earth System Sciences, an open access journal of the European Geosciences Union (EGU).

Stretching over three continents and persisting for many centuries, the Roman Empire was home to an estimated 70 million people. In such a vast area ensuring a stable food supply was no easy task, particularly given the variable and arid climate of the Mediterranean region. So how did the Romans maintain reliable food supplies to their cities for centuries under such challenging conditions?

To find out, Brian Dermody, an environmental scientist from Utrecht University, teamed up with hydrologists from the Netherlands and classicists at Stanford University in the US. The researchers wanted to know how the way Romans managed water for agriculture and traded crops contributed to the longevity of their civilisation. They were also curious to find out if these practices played a role in the eventual fall of the Empire.

"We can learn much from investigating how past societies dealt with changes in their environment," says Dermody. He draws parallels between the Roman civilisation and our own. "For example, the Romans were confronted with managing their water resources in the face of population growth and urbanisation. To ensure the continued growth and stability of their civilisation, they had to guarantee a stable food supply to their cities, many located in water-poor regions."

In the Hydrology and Earth System Sciences paper, the team focused on determining the water resources required to grow grain, the staple crop of the Roman civilisation, and how these resources were distributed within the Empire. It takes between 1000 and 2000 litres of water to grow one kilo of grain. As Romans traded this crop, they also traded the water needed to produce it - they exchanged virtual water.

The researchers created a virtual water network of the Roman world. "We simulated virtual water trade based on virtual-water-poor regions (urban centres, such as Rome) demanding grain from the nearest virtual-water-rich region (agricultural regions, such as the Nile basin) in the network," explains Dermody.

The team used a hydrological model to calculate grain yields, which vary depending on factors such as climate and soil type. The authors used reconstructed maps of the Roman landscape and population to estimate where agricultural production and food demand were greatest. They also simulated the trade in grain based on an interactive reconstruction of the Roman transport network, which takes into account the cost of transport depending on factors such as distance and means of transportation.

Their virtual water network indicates that the Romans' ability to link the different environments of the Mediterranean through trade allowed their civilisation to thrive. "If grain yields were low in a certain region, they could import grain from a different part of the Mediterranean that experienced a surplus. That made them highly resilient to short-term climate variability," says Dermody.

But the Romans' innovative water-management practices may also have contributed to their downfall. With trade and irrigation ensuring a stable food supply to cities, populations grew and urbanisation intensified. With more mouths to feed in urban centres, the Romans became even more dependent on trade whilst at the same time the Empire was pushed closer to the limits of their easily accessible food resources. In the long term, these factors eroded their resilience to poor grain yields arising from climate variability.

"We're confronted with a very similar scenario today. Virtual water trade has enabled rapid population growth and urbanisation since the beginning of the industrial revolution. However, as we move closer to the limits of the planet's resources, our vulnerability to poor yields arising from climate change increases," concludes Dermody.

Source:  European Geosciences Union (EGU)

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