Wednesday, 15 March 2017

An exciting new development in soil phosphate oxygen isotope analysis...by Andi Smith

In early February, Andi Smith (Stable Isotope Facility) and Sammi Coyle (PhD student joint with The University of Nottingham and Scotland’s Rural College) visited collaborators at Rothamsted Research (North Wyke, Devon), to learn more about one of our most exciting stable isotope techniques developments. Rothamsted Research is a world-leading research centre in plant and soil science for sustainable agriculture. Here, Andi explains a bit more about their visit and why we should all be interested in phosphate oxygen isotope analysis...

Sammi and I visited Rothamsted Research, North Wyke in Devon to help us perfect a technique for extracting inorganic phosphate from soil samples, so we can analyse these for their oxygen isotope composition.

But firstly, why are we interested in isotopes of phosphorus?


Phosphorus is a key nutrient for all life, critical for the development of cells and functioning of DNA and RNA. It is therefore one of a few key elements which are fundamental for the development of all living things along with nitrogen and carbon. When these elements are lacking in the environment, they are often described as limiting nutrients. For this reason, modern farming practices have developed specific fertilisers which help increase the levels of phosphorus and nitrogen in the soil system. This has helped us drastically improve crop yields. However, where these nutrients are lost into streams and rivers, they can promote the growth of algae and damage, often delicate, natural ecosystems. It is therefore important to understand and trace how these nutrients behave when added into the soil system. This is where isotopes can play their part….

For many years, nitrogen cycling in soil systems has been characterised by the analysis of nitrogen (15N) and oxygen (18O) isotopes in nitrate (NO31-). However, phosphorus only has one stable isotope (31P), and until recently, it has only been possible to extract the 18O signature of phosphate (PO43-) in clean waters (e.g. seawater). However, ground-breaking work undertaken in 2010 at ETH Zurich has made it possible for us to extract inorganic phosphate from soils (which also have many organic phosphorus compounds), so we can now start to trace the phosphate cycle far more closely. It is this method for extracting inorganic phosphorus that we have been working on for the last week.

Extracting inorganic phosphate


Whilst quite complex and time consuming (so I don’t go into details here), the extraction technique is based around a few relatively simple principles.

At the first stage, soil samples are treated with acid to release the inorganic phosphate into solution. After this, there are several stages where phosphate compounds are precipitated out of solution and washed to remove any unwanted contaminants containing oxygen, which would interfere with the analysis. The final stage is to add a silver solution which precipitates with the phosphate to form silver phosphate crystals- it is these crystals we analyse for their oxygen isotope composition

From L-R: First the soil must be filtered to break up any large particles, a messy job; Filtering out the bright yellow APM
crystals, this is where all the phosphate has been trapped.

What’s next?


Now that we have a working method to use at the BGS’s Stable Isotope Facility, we hope to be able to work on a whole range of new projects for which this isotope technique is critical. We believe this technique will be invaluable to further our understanding of the interactions of fertilisers and soils systems (this is the focus of Sammi’s PhD) but that we could also apply this technique to studies of phosphate pollution, phosphate source tracing and potentially palaeoclimate reconstructions. Watch this space….

Sammi and I would both like to thank Dr Verena Pfahler and Dr Steve Granger for hosting us at Rothamsted Research and to The University of Nottingham and Scotland’s Rural College for sponsoring our visit. Sammi would also like to thank UoN and SRUC for co-funding her PhD project. We hope to have some great data for you soon!

Wednesday, 8 March 2017

Deploying and servicing a seismic network in Central Italy...by Simone Mancini

Seismicity map of the Amatrice-Norcia sequence updated on 20 January 2017.
From a scientific point of view, the seismicity that is hitting Central Italy presents itself as an unmissable opportunity for seismologists to analyse the triggering and the evolution of an earthquake sequence. From the tens of instruments installed in the affected area, a huge amount of data is being collected. Such a well-recorded sequence will allow us to produce a comprehensive seismic catalogue of events. On this big quantity of data, new algorithms will be developed and tested for the characterisation of even the smallest earthquakes. Moreover, they will enable the validation of more accurate and testable statistical and physics-based forecast models, which is the core objective of my PhD project.

The Central Apennines are one of the most seismically hazardous areas in Italy and in Europe. Many destructive earthquakes have occurred throughout this region in the past, most recently the 2009 Mw = 6.4 L’Aquila event. On August 24th, just 43 km North of the 2009 epicentre, an earthquake of magnitude 6.0 occurred and devastated the villages of Amatrice and Accumoli, leading to 298 fatalities, hundreds of injured and tens of thousands people affected. The mainshock was followed, in under an hour, by a Mw = 5.4 aftershock. Two months later, on October 26th, the northern sector of the affected area was struck by two earthquakes of magnitude 5.4 and 5.9, respectively, with epicentres near the village of Visso. To make things even worse, on October 30th the city of Norcia was hit by a magnitude 6.5 mainshock, which has been the biggest event of the sequence to date and the strongest earthquake in Italy in the last 36 years. Building collapses and damages were very heavy for many villages and many historical heritage buildings have reported irreparable damages, such as the 14th century St. Benedict cathedral. On January 18th, other four earthquakes of magnitude greater than 5 have been recorded near the villages of Montereale and Pizzoli, in the southern sector. Luckily, there have been no further fatalities since the very first event of August 24.

St Benedict's Cathedral (Norcia), erected in the late 14th century and completely destroyed after the
Mw 6.5 earthquake of 30th October.
Immediately after the first big event, an emergency scientific response team was formed by the British Geological Survey (BGS) and the School of GeoSciences at the University of Edinburgh, to support the rapid deployment of high-accuracy seismometers in collaboration with the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The high detection capabilities, made possible by such a dense network, will let us derive a seismic catalogue with a great regional coverage and improved magnitude sensitivity. This new, accurate, catalogue will be crucial in developing operational forecast models. The ultimate aim is to understand the potential migration of seismic activity to neighbouring faults as well as the anatomy of the seismogenic structure and to shed light into the underlying physical processes that produce the hazard.

Thanks to the quick response of the National Environmental Research Council (NERC) and SEIS-UK, 30 broadband stations have been promptly dispatched from Leicester and arrived in less than 48 hours in Rome. There, a group of 9 people composed by INGV and BGS seismologists, technicians and PhD students (including myself) from University of Bristol, Dublin Institute for Advanced Study (DIAS) and University of Ulster were ready to travel across the Apennines to deploy this equipment. The first days in Rome were all about planning; the location of each station was carefully decided so as to integrate the existing Italian permanent and temporary networks in the most appropriate way. After having performed the 'huddle test' in the INGV storage room, which involves parallel checking of all the field instrumentation in order to ensure its correct functioning, we packed all the equipment and headed to the village of Leonessa, a location considered safe enough to be used as our base camp (despite the village being damaged and partially evacuated after the 30th October event).

Preparing instrumentation for the huddle test in one of INGV's storage rooms.
In order to optimise time and resources, and to start recording data as soon as possible, we decided to split in three groups so that we could finish our work between the end of August and the first week of September. Each seismic station is composed of a buried sensor, a GPS antenna, a car battery, a regulator and two solar panels. The current deployment will stay for 1 year and will be collecting data continually. Each sensor had to be carefully buried and levelled to guarantee the highest quality of recording, which was a strenuous challenge when the ground was quite rocky!

Aside from the scientific value of the expedition, the deployment week was a great opportunity to get to know each other, share opinions, ideas and, of course, get some training in seismology! At the end, we managed to install 24 stations around an area of approximately 2700 km2.

As this type of seismic station didn’t have telemetry, each needed to be revisited to retrieve data. For this purpose, from October 17th, Dr David Hawthorn (BGS) and I flew to Italy again and stayed there for the following ten days to service the seismometers and to do the first data dump. Our goals were also to check the quality of the first month of recordings, to add a second solar panel where needed, and to prepare the stations for the forthcoming winter. To do that, a lot of hammering and woodworking was needed. We serviced all the sites, raising the solar panels and GPS antennas on posts, which were securely anchored to the ground, to prevent snow from covering them. The stations were all in good conditions, with just minor damages due to some very snoopy cows.

Left: Typical setting of our deployed stations. On the left, the buried sensor. Its cables, buried as well, connect it to the
 instrumentation inside the black box (a car battery, and a regulator). On the right, the solar panel (a second one was added in
 October service) and the white GPS antenna. Right: Dr David Hawthorn (BGS) servicing the stations – A second solar panel
 was added. Panels and GPS antennas were raised on posts anchored to the ground through timbers.
Typical setting of our deployed stations. On the left, the buried sensor. Its cables, buried as well, connect it to the instrumentation inside the black box (a car battery, and a regulator). On the right, the solar panel (a second one was added in October service) and the white GPS antenna. Dr David Hawthorn (BGS) servicing the stations – A second solar panel was added. Panels and GPS antennas were raised on posts anchored to the ground through timbers.

On October 26, just the night before leaving for Rome, we experienced first-hand the frightening feeling of a mainshock just below our feet. Both the quakes of that evening surprised us while we were inside a building; the rumble just few seconds before the quake was shocking and the shaking was very strong. Fortunately, there were no severe damages in Leonessa but many people in the village refused to spend the night in their own houses. Also, it was impressive to see the local emergency services response: only a few minutes after the first quake, policemen were already out to patrol the inner village checking for any people experiencing difficulties.

Throughout our car transfers from one site to another we frequently found roads interrupted by a building collapse or by a landslide, but we could also admire the mountains with a mantle of beautiful autumnal colours and the spectacular landscapes offered by the Apennines, like the Monte Vettore, the Gran Sasso (the highest peak in the Apennines) and the breath-taking Castelluccio plain near Norcia.

View of the Norcia Plain, near to the 24th August Mw5.3 and 20th October Mw 6.5 earthquake epicentres.
From my point of view, I learned a lot and really enjoyed this experience. I feel privileged to have started my PhD in leading institutions like the British Geological Survey and the University of Bristol and, at the same time, to be able to spend time in my home country (yes, I am Italian…) with such interesting scientific questions. What I know for sure is that we will be back there again.

Simone Mancini is a 1st year PhD student with the British Geological Survey and the University of Bristol. 

Monday, 6 March 2017

Starting my PhD with the British Geological Survey...by James Williams

Me standing on the front helideck of the ship in the
North Atlantic. 
Hello, my name is James and I have recently started my PhD at the School of Earth and Ocean Sciences, Cardiff University and the British Geological Survey. During my PhD, I will investigate the mechanisms that have driven glacial retreat along the Antarctic Peninsula coastline over the last 2,000 years. In order to do this, I will utilise the geochemistry of diatoms collected from a suite of British Antarctic Survey sediment cores. Diatoms produce a hard shell (frustule) of silicate that is preserved in the sediment record, the geochemistry of which can be used as a proxy of glacial discharge and meltwater input to the ocean as a result of melting.

During the third year of my undergraduate degree, I studied at Stockholm's Universitet as part of the ERASMAS programme. It was here that I became fascinated with palaeoclimate, palaeoceanography and all things diatom! For my Bachelors thesis, I chose to reconstruct sea ice concentrations using marine diatom assemblages. It was whilst looking down the microscope at these beautiful, ornate, fossil algae that I decided that I wanted to pursue research within the field of palaeoclimate.

I have been very lucky during the beginning months of my PhD. In October, I attended the ‘Applications of Stable Isotope Geochemistry’ workshop at the Scottish University Environmental Research Centre laboratory in East Kilbride. Whilst there, I learned about some of the fascinating applications of stable isotope geochemistry beyond palaeoclimate. These applications include using stable isotopes in mineral exploration, ecology and (arguably the most fascinating) in reconstructing the movement of King Richard the 3rd across the United Kingdom during his lifetime. Moreover, participants were taken on a guided tour of the lab facilities, and were able to gain hands on experience of the preparation methods used for analysis of stable isotopes. I took part in the preparation of samples using the carbonate line, which involved some very exciting liquid nitrogen and a very hot hairdryer! The workshop was a fantastic opportunity to meet other like-minded early career stable isotope geochemists, and was rounded off with a tour to the very impressive, gargantuan, Accelerated Mass Spectrometer laboratory.    
 
From L-R: The Akademik Tryoshnikov in all her glory which was my home for the 4 week expedition from Bemerhaven
 (pictured) to Cape Town; the CTD wet lab and the Niskin Bottle rosette where I conducted most of my work.
In November, I took part in the Antarctic Circumnavigation Expedition (ACE) Maritime University. The ACE cruise has been organized by the Swiss Polar Institute, with the aim of conducting science in the Southern Ocean and Antarctic Islands. I boarded the Akademik Tryoshnikov, a Russian ice breaker, in the cold and grey of Bremerhaven and was bound for Cape Town. We set sail during storm Abigail, and I had to find my sea legs very quickly as we transited through the English Channel. Upon reaching the Atlantic Ocean, we began with the lecture series that formed the Maritime University. These lectures were a fantastic introduction to the various aspects of physical oceanography, ocean chemistry and biology that play a fundamental role in the climate system. As part of the seagoing University, I was able to shadow a scientist who conducted research in a field of my interest and assist in their lab work. Given my interest in diatoms and ocean chemistry, I naturally gravitated towards the Conductivity Temperature Depth (CTD) profiler. Everyday, at 8 am and 3 pm, I would go to the wet lab and prepare the Niskin bottles on the CTD rosette for deployment. These Niskin bottles are closed at specific depths within the water column, bring water samples from depth to the scientists onboard. I would then oversee the deployment of the rosette, and take my position of at the helm of the computer. The CTD was lowered to 500 m, whilst recording profiles of oxygen saturation, salinity, temperature and chlorophyll concentrations analysed, and the Niskin bottles closed on the return to the surface. I would then distribute the water samples to the scientists. Being the only geologist onboard, everyone was interested in just what it is that we do, and how we do it.

Southern Ocean diatoms. 
Upon returning to Cardiff, I have been reviewing the literature previously published from the Antarctic Peninsula, with the aim of placing my research into the context of the work already conducted. I have also spent time at BAS sampling cores, and learned the sample preparation methods for stable isotope analysis at Nottingham. In the coming weeks, I will be setting up the lab for cleaning diatoms at Cardiff and will be running my very first samples on the Stepwise Fluorination Line at BGS. Stay tuned over the coming months for updates on the progress of these first analyses, as well as some more insight into why scientists are concerned by melting glaciers along the Antarctic Peninsula, and how we can develop records of melting using diatom stable oxygen isotopes.    

My supervisory team consists of Jennifer Pike and Elizabeth Bagshaw (Cardiff University), George Swann (Nottingham University), Melanie Leng (BGS) and Claire Allen (BAS). James can be found on twitter using the handle @jameswilliams108