Meera Senthilingam: Hello and welcome to episode one of the Diamond Light Source Podcast, where we take a look at the latest science from the UK’s largest Synchrotron facility. In this first edition of the show, I’ll be taking a look inside this national science institute to find out how it works. Trevor Rayment: The electron is accelerated to close to the speed of light and then forced to go round a bend, passing through a magnetic field. The electron as it goes around the bend gives out light. Meera Senthilingam: Trevor Rayment will be explaining more about what Diamond is and how it works. Plus, we’ll be catching up with some of the key research which took place over the past year, including how Diamond has revealed the real chemical composition of a comet. John Bridges: One of the things we are finding are iron oxides and chromium oxides. Now that’s unusual and not the sort of thing we expect to find in a comet. Meera Senthilingam: So watch this space for the cosmic soup that spawned our solar system. We’ll also be finding out how chemists are worming their way into nature's good books. Mark Hodson: We can take these super metal munching earthworms and take them from contaminated sites, put them into other contaminated sites which don’t have earthworms and help the earthworms develop the soil, stimulate soil production and make the eco system healthier. Meera Senthilingam: How are the earthworms capable of doing this? Mark Hodson will reveal all as he explains how these earthworms seem to survive where no other organism dares go. Meera Senthilingam: Before we take a look at the science happening here at Diamond Light Source let's find out a bit more about how it works and what it does. Located in South Oxfordshire the synchrotron opened in January 2007. It covers an area the size of 5 football pitches and took 4 years to build. At its heart is a powerful particle accelerator, whizzing electrons at high speed around a large race track style ring. As they circulate through this ring, the electrons pass through specially designed magnets which make them produce intense beams of X-rays, ultra-violet and infra-red light. Here’s Diamonds director of physical science Trevor Rayment, telling us how they produce this very special light. Trevor Rayment: The electron is accelerated to close to the speed of light and then forced to go round a bend and passed through a magnetic field. When it goes round the bend it gives out light. Trevor Rayment: Well what we do is we take electrons and we make them go round in a circle. We do that because it takes energy to get them up to a very high speed and then once you’ve done that you need to keep them going round at a constant speed for as long as possible. Now the way we do that is in three stages. We start by first of all making electrons, then having done that we accelerate them along a straight accelerator, to get them to a high speed, but not high enough speed to join electrons already going around the ring and we put them into a booster until their energy is the same as the electrons circulating around the ring and when they are at the same energy we let them into the ring and they join their friends going round. Trevor Rayment: Well right now we are sitting overlooking the experimental hall, which when you look at it, most of what you see is a lot of pipe work. But if you were to look as a bird might from above, down on the ring you would see a 24 sided polygon, 24 straight sides and corners. Now that’s important as electrons go in a straight line if you just leave them to their own devices and its only when you turn them round a corner that they actually give out light. So we’ve got the 24 sided polygon and at each of the corners we have a magnet which deflects them along the next side of the polygon. Trevor Rayment: If you were to walk all the way around its 561 metres – I think that’s right. In practical terms it takes you more than 15 minutes to walk around the experimental hall so it is quite large. Meera Senthilingam: OK so within this large coin you just have these electrons going at very high speed, but what do you actually do with this to use it in the research? Trevor Rayment: If you know that light emerges every time an electron goes round a bend or follows a curve then the simplest way to improve or increase the intensity is to make the electron go through a series of sequential bends. You make it wiggle as it goes along its path. And so if you have ten wiggles or ten magnets, then what will happen is you’ll end up with ten times the intensity – we call those wigglers and those are used at Diamond. Meera Senthilingam: And so these insertion devices essentially help determine which types of radiation are being created and these spaces where they happen are called beam lines. Trevor Rayment: Yes that’s right the insertion devices create the radiation which then streams off tangentially from the storage ring and then it goes into a special shielded hutch/lead room where we select out radiation which we need. After that it will then impinge upon our sample and we do whatever experiments we have to do. Trevor Rayment: Well at the moment there are twelve and these produce very different types of radiation. If I give you some examples: At the most gentle end we have a beam line which isn’t quite ready that produces infra-red radiation and one which was commissioned just a few days a go, produces ultra-violet radiation. And then there are instruments that produce X-ray radiation which will penetrate through centimetres of matter. These are used through a very different range of applications from studying the conditions at the centre of the earth, to say looking at the composition of paint, say in pictures. Trevor Rayment: A very wide variety if scientists in a nutshell but let me give you some examples. If I start with areas of biology, then there are scientists who are trying to understand disease at a molecular level. These are followed by scientists who are attempting to develop new drugs and have collaborations with industry. Going on from that the range then goes into the physical sciences where people are trying to invent materials that might improve for example your I-pod. There are people working on archaeology, who are trying to understand where various bits of pottery come from. We’ve even had people looking at components of meteorites. Meera Senthilingam: Trevor Rayment – He’s Diamond's Director of Physical Sciences and speaking of meteorites and other objects out in space, here’s Leicester University’s John Bridges. John Bridges: It’s a comet which formed beyond Neptune in the Kuiper belt but which was disturbed by Jupiter, by a close interaction with Jupiter in the solar system and in 2004 a space mission called Stardust was able to go in front of it, through its coma and sample samples of dust, then bring it back to earth so we can find out what the comet is made of uniquely. John Bridges: Well comets are most primitive of objects in our solar system. They haven’t undergone all the plate tectonics, erosion – all the different types of alteration that the rocks on earth have undergone. So when we are looking at comets we are understanding what processes were occurring in the early solar system. John Bridges: We took slices of an aero-gel collector from the stardust craft – a very low density silica gel. We took these wafers with the tiny grains of the comet, a millionth to a thousand of a millionth of a millimeter across. We took those to Diamond and used their very bright X-ray source. When we focus an X-ray source like that onto our grains, then we can get fluorescence, or the emissions of characteristic X-rays from the grains and those packets of energy, those X-rays tell us what the grain is actually made of. John Bridges: One of the things we are finding are iron oxides and chromium oxides. Now chromium oxide, from a mineral called chromite, is a high temperature mineral which forms at many hundreds of degrees centigrade. Now that’s unusual, it’s not the sort of thing we expect to find in a comet. The traditional view of a comet is a dusty ice ball – what on earth is this high temperature mineral doing in there? That’s telling us this traditional view of comets – maybe that’s not true. John Bridges: Yes it's unexpected – we were expecting to find almost invariably low temperature minerals, remnants of ices which formed in the outer cold part of the solar system but it looks like some of the materials have been bought in from the inner part of the solar system. There has been a grand ‘mixing’ going on in the solar system since the early part of the solar systems history. John Bridges: Well we also found, diametrically opposed if you like to chromium oxide, we found iron oxides, minerals called magnetite and hematite. These are at the other end of the spectrum of temperature in that these probably formed at relatively low temperatures which is OK for comets, but from trickles of water, so it looks like very occasionally in small amounts, there may have been trickles of water on the nucleus of Comet Wild 2 and that’s not quite what we were expecting. So there has been more going on in the comet and it’s a more complex system that we were expecting. John Bridges: I think its telling us not all comets are the same. Wild-2 is a Jupiter family comet which formed in the Kuiper belt and there are other comets way beyond the outer extremes of the solar system. So not all comets are the same, some like Comet Wild 2 have sampled materials from the inner solar system as well as the outer solar system. Meera Senthilingam: So now that you know there has been a variety of mixing when it comes to making these comets, what else will you be looking into and what else would you like to find out? John Bridges: I think we need to find out accurately the bulk composition of the comet. We can do that at Diamond as well, for instance we have these whole cometry tracks and in order to find out what their bulk composition is, in other words what is their percentage of iron or silicone, of all the other elements, what they are. Then we can take that composition inventory if you like and compare it to our meteorites and put it in context – how does Comet Wild 2 compare to other planets. Then we have a better idea about the composition of the solar system and the building blocks of the solar system. Meera Senthilingam: John Bridges explaining how Diamond is helping to shed some light on the chemical composition of the cosmos. He’s based at Leicester Universities space research centre. Quick Fact: Did you know that the electrons at Diamond are moving so fast that they could travel around the world seven and a half times every second. That’s close to the speed of light. Meera Senthilingam: Now we’ve heard how Diamond is helping scientists to learn more about the composition of comets but we are heading more down to earth quite literally as we venture down beneath the soil surface and into the world of the earthworm. These creatures appear to be able to thrive even in land so contaminated that little else will grow there, suggesting they may be able to help us clean up contaminated environments. Here’s Mark Hodson from the University of Reading. Mark Hodson: Well the mystery about these earthworms is why they are actually there in the first place. We go to these sites and they are former mining sites leftover from the 19th century, metal levels are really high and to all intents and purposes these are contaminated sites, plants have trouble growing there but when you dig in the soil, you find earthworms. The big question is why are they there? How do they cope with all the various metals? Sometimes it looks like the earthworms have evolved, it looks like they have been driven by the concentrations in metals to evolve and they have their own methods of dealing with it and we are still working on it. There are a variety of mechanisms that they can use to cope with those metals and some of the research we are involved in using the synchrotron at Diamond can actually tell us what form the metals are in both in the soil and after they have been ingested by the earthworm. The earthworms take the metals in and they change the form of the metal to make them less toxic. Mark Hodson: It varies from site to site, the main site we are working at the moment is a former lead mining site in Wales so the contaminant there is lead. We’ve also got an interest in a site in the South West where there is lots of arsenic and copper and the final site we are working on is up in the Penine ore field and is contaminated by lead and zinc primarily. Mark Hodson: Well that’s the million dollar question really, it’s what we are trying to find out. What it looks like in some situations is that ingestion of these metals, triggers the production of a special protein, which essentially wraps around the metal and makes that metal non-toxic to the earthworm. So that’s one mechanism which is going on particularly for the arsenic. That works for copper as well. For some of the earthworms from the lead contaminated site, what it seems to look like is again there is more of a different type of protein and in this case it is a protein which is normally used for moving calcium around your body. Lead is very similar to calcium, it has a similar sort of size when its an ion and a similar charge. And it looks as though earthworms able to live in the lead contaminated sites are good at producing more of this protein, modifying it slightly so they can deal with all the lead and immobilize it. Meera Senthilingam: So you know this about these earthworms now and that they can live in these harsh environments but do they have any applications or uses? Mark Hodson: There are a couple of possibilities out there. One is that we could take these super metal munching earthworms and take them from contaminated sites and put them into other contaminated sites which don’t have earthworms and help the earthworms develop the soil and stimulate soil production to make the eco-system healthier. Another possibility is to take the earthworms to contaminated sites and they seem to change the form of the metal in the soil once they have processed the soil and that might make it more extractable by plants. So we could grow plants on these sites and with the help of the earthworms the plants will be able to pull the metals out of the sites and help to remediate the site that way. Mark Hodson: We don’t have a full answer yet, but we have done experiments where we have grown plants in contaminated soil with and without earthworms and when the earthworms are present the plants are able to pull out a lot more metals. Now precisely why that is we don’t know. We have started doing some experiments and essentially, we have looked at earthworm poo and see whether the form of the metal in that poo is different from the bulk soil. At the moment its too early to say how the difference affect the ability of the plant to take the metals out but its certain that the plants are able to take more metals out. Once we can answer that scientific question we can start to apply it in real life and to real contaminated sites. Meera Senthilingam: Now you say these earthworms are only in some contaminated areas, so how do you think they have only ended up in certain areas and not others with contaminated soil? Mark Hodson: Sometimes it can just be that a contaminated site was so disturbed, that while that site was being used by industry it became impossible for organisms to live there. Earthworms migrate very slowly, on average about 10 metres a year, they might encroach into areas where they are not present. Some sites may be so big that earthworms have just not got there yet, they haven’t had time to spread into those areas. Mark Hodson: OK, there are 2 advantages to using earthworms to remediate contaminated sites. One of course is that it’s just good to remediate contaminated sites, former brown belt land for building purposes or for building parks and that sort of thing rather than building on Greenfield sites. The actual advantage to using earthworms or plants to remediate sites is there is a lot less environmental impact and it is far more environmentally sustainable than simply digging up that soil and moving it somewhere else which is the sort of classic remedial treatment used at the moment. It’s called ‘dig and dump’. It works very well but it’s not sustainable, so using earthworms and plants is a more sustainable option. The key thing with the synchrotron is it allows us to burrow down into the detail and find out what form those metals are in, in both the soil and the earthworms. So for example in one of sites we can say that in the soil the copper atoms, the contaminate are surrounded by oxygens, but once we use the synchrotron we can see that in the earthworm that copper is modified and is surrounded by sulphurs and most probably that sulphur is related to a protein surrounding the copper and rendering it immobile. Mark Hodson: What we are really hoping to do is to use Diamond to answer these fundamental questions. Look at the metal speciation, the form of the metal in the earthworm and in the soil after its been processed by them. Once we understand fully how these metals have changed their form and the impact earthworms have on metals, we’ll be able to realize some of these ideas to make earthworms remediate contaminated soils and help the earthworms to help us to to remediate the contaminated soils. Meera Senthilingam: That was Mark Hodson from the University of Reading. That’s it for this edition of the Diamond podcast but do join us again in April when we’ll be back with more of the latest news and discoveries from Diamond, including a special insight into how Diamond is helping the life sciences. In the meantime if you have any questions about Diamond or the research taking place there, the email address is [email protected]. Thank you to Trevor Rayment, John Bridges, Mark Hodson and the team at Diamond Light Source. Production this month was by Chris Smith of the Naked Scientist.com.
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