Chemistry World Podcast - August 2008
00:10 -- Introduction
2:08 -- The moon may not be made of cheese, but it's wetter than expected
5:05 -- Chemistry on Mars
7:10 -- Eric Wolff from the British Antarctic Survey explains how ice holds ancient and vital chemical clues about climate change
14:30 -- Can humans sense light through their skin?
17:32 -- How mercury could be responsible for Dolphins beaching themselves
19:40 -- Malcolm Forbes, chemistry professor from the University of North Carolina, explains how chemical techniques are helping create the perfect pint
23:36 -- A live experiment in beer chemistry in the Chemistry World garden, and can you answer our Olympic-themed chemical conundrum?
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
(00:10 -- Introduction)
Interviewer - Chris Smith
Hello! Welcome to Chemistry World with Victoria Gill, Richard Van Noorden, Manisha Lalloo and James Mitchell Crow. I'm Chris Smith. Coming up, why the moon is actually a much wetter place than we first thought.
Interviewee - Richard Van Noorden
We've always that moon is completely bone dry and now it turns out some researchers have actually managed to find some water. They re-examined some of the soil dug out by the Apollo missions in the 1970s and they looked at these glassy beads that are scattered all over the soil. They come in green and orange varieties, but in the middle of these beads, they did detect a small amount of water.
Interviewer - Chris Smith
So, no cheese then. That's on the way. Also talking of water, we'll be finding out what ice cores from Antarctica can tell us about climate change.
Interviewee - Eric Wolff
We are much higher than it has been at any time in the last 800,000 years. So it ranges between a 170 in the cold periods and about 300 in the very warmest periods and right now we're at 380 this year and rising by 2 parts per million per year.
Interviewer - Chris Smith
That's Eric Wolff from the British Antarctic Survey who will be joining us later and we'll also be celebrating summer with a drink.
Interviewee - Victoria Gill
So we're going to see if Rich can tell the difference between the beer that has been exposed to sunlight and hopefully there's been some interesting photochemistry affecting its flavour and the beer that's been lovingly refrigerated. So this is beer number 1 (sound of beer being poured)
Interviewer - Chris Smith
I can see you've worked in a pub Vic. Can he have some beer with his head please? Now they say, you shouldn't taste your chemistry experiments, but this was one exception that the team were willing to make, that's the science of beer and photochemistry and it's coming up later and we'll also be solving last month's chemical conundrum.
Interviewee - Richard Van Noorden
If you had a standoff between hydrogen, carbon, and chlorine, which has the highest first ionization energy.
Interviewer - Chris Smith
The answer is on the way and if you sent in a chemical solution, then stay tuned to find out if you're one of this month's winners.
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(2:08 -- The moon may not be made of cheese, but it's wetter than expected)
Interviewer - Chris Smith
Now for anyone who is disappointed to learn as a child that the moon is really made of cheese, there's some consolation because it now it looks like scientists have found that in fact it's got a lot of water up there. Richard.
Interviewee - Richard Van Noorden
Well, not a lot of water Chris. We've always thought that moon is completely bone dry and now it turns out some researchers have actually managed to find some water. They re-examined some of the soil dug out by the Apollo missions in the 1970s and they looked at these glassy beads that are scattered all over the soil. They come in green and orange varieties, and it's the titanium and the magnesium that's causing this colour, and when they looked at these beads, there's no volatile components like water or chlorine or fluorine on the surface, as you would expect, the moon is very small, it doesn't have an atmosphere. All of these volatile components would have floated away long ago, that's why the moon is bone dry, but in the middle of these beads, they did detect a small amount of water and doing some modelling to work out perhaps how quickly the water diffused away from these beads, which they think were formed during volcanic eruptions, these beads have sort of melted glassy magnesium or titanium.
Interviewer - Chris Smith
Were they formed in situ on the Moon or presumably they were formed on the early Earth and then when the Moon got formed from the Earth's crust, it got carried with this. Is that what happened?
Interviewee - Richard Van Noorden
Well that's the question. That's what they don't know. They actually found, as they were modelling that the amount of water that would have been present in these beads is about the same as what's in the Earth's mantle and that obviously gives rise to the question, did these come from the Earth in an impact. But they don't think it was a meteoroid from outer space because there doesn't seem to be things like nickel there that would have come from the meteoroids as well. So, now the question is, how was the water preserved in these glassy components. Did something crash in from the Earth as you say is very intriguing and they seem to just struck lucky. They seem to just found these beads. People have been looking at these soils for sometime and they happen to pick some that seem to have water in. It may be that water isn't scattered all over the Moon in these beads and that they just picked exactly the right spot.
Interviewer - Chris Smith
So, what's the implication of this then? Where next, what are the big questions that this has opened up?
Interviewee - Richard Van Noorden
Well the question is, was there water on the early Moon, it could have hung around long enough to something interesting to happen or did it all disappear very quickly leaving the mostly dry Moon that we know today and can we find more water in other types of beads. Can we work out how the water got there perhaps by more detailed analysis on the hydrogen and deuterium isotopes of the water? So that's still to be addressed, but it's very exciting that the Moon is not really as dry as we thought.
Interviewer - Chris Smith
But it does sound like it's going to necessitate a return visit to answer some of those questions.
Interviewee - Richard Van Noorden
Well, the authors from the Brown University in Rhode Island, US say that even manned crews might not actually find water. You know they think that they were quite lucky and so they are not even sure that manned crews will find water because we should see many trying, and the US's race to the Moon continues at its current pace, we might see manned visits to the Moon by 2020. So perhaps the mystery will be resolved.
(5:05 -- Chemistry on Mars)
Interviewer - Chris Smith
Thanks Richard. While sticking with the subject of water and our near cosmic neighbours scientists are working on Mars, Manisha to understand a bit more about the surface chemistry there.
Interviewee - Manisha Lalloo
Yeah, there has been quite a lot of exciting chemistry going on, on Mars at the moment and as a result of the, Phoenix Mars Lander which touched down in the arctic plains on the 25th of May and so over the last couple of months, scientists have been busy carrying out chemistry experiments that can help us study the history of water on Mars and study whether Mars has the potential to support life.
Interviewer - Chris Smith
What sort of things have they been doing to answer those questions?
Interviewee - Manisha Lalloo
From a chemist's perspective, I guess there are two main experiments they have being carrying out. The first is being using the wet chemistry laboratories on Phoenix and which is part of an instrument called MECA, which is Phoenix's Microscopy, Electrochemistry and Conductivity Analyzer. Basically though wet chemistry experiments are carried out in these miniature chemistry labs and which is the size of a tea cup and contain ion-selective electrodes which can measure things such as what type of ions are in the solution and the pH of the solution of soil and water and the conductivity of the soil. So far they have found that the soil of Mars is alkaline, it's about a pH of 8 or 9 and they've also found sodium, potassium, magnesium, chloride and sulphate salts.
Interviewer - Chris Smith
How do the abundances of those things compare with the same chemicals on Earth? Have we got a composition of the surface in Mars similar to Earth or is it very dramatically different?
Interviewee - Manisha Lalloo
At the moment, they've still got a lot of analyzing left to do and it will take weeks and months before they can determine the true significance of these results. I spoke to the lead and scientist, Sam Kounaves and he says that they don't know the exact levels of salts and ions in the solutions at the moment but somewhere in between tap water and seawater.
Interviewer - Chris Smith
Sounds tasty. So they haven't actually got that long to do all this, have they? Because the probe can only work until winter comes and then that's it.
Interviewee - Manisha Lalloo
Yeah, that's true and at the moment the scientists have been working to a Mars day, they've been working to Mars time which is the 24.7 Earth hour day and that mission is scheduled to last for 90 sols which is 90 Martian days. So that should end at the end of August, but the scientist I talked to, said that they can hopefully extend it for a couple of months, but that (UNCLEAR 7:16) to get all the chemistry done.
Interviewer - Chris Smith
And a Mars a day really does help you at work, rest and play then.
Interviewee - Manisha Lalloo
I guess, yeah.
Interviewer - Chris Smith
Thank you to Manisha Lalloo.
(7:10 -- Eric Wolff from the British Antarctic Survey explains how ice holds ancient and vital chemical clues about climate change)
Interviewer - Chris Smith
Well coming back to Earth now and to Antarctica which paradoxically despite being the coldest place on Earth, also holds many of the answers to the question of global warming. Here's is Eric Wolff.
Interviewee - Eric Wolff
Antarctica in various places holds the key to understanding a lot of aspects of the Earth, especially to do with climate change. The work that I do is particularly on ice cores and ice cores are the clearest way we have of knowing how the famous green house gases, carbon dioxide and methane have changed in the past and although we think of Antarctica as very remote, it does have a significant effect on global climate. So, we do really need to understand that just as much as anywhere else in the world.
Interviewer - Chris Smith
So, when we are talking about the ice in Antarctica, how thick is it?
Interviewee - Eric Wolff
In the central parts of Antarctica, the ice can be up to 4 km or 3 miles thick, of course around the coast it's very much thinner, but that 4 km has been snow fall falling over thousands and millions of years, actually the ice sheets been there probably continuously for at least 20 million years and so it builds up to these incredible thicknesses.
Interviewer - Chris Smith
And so once you want to unlock the data that's in that ice, how do you get at it, obviously you got to drill it out in someway.
Interviewee - Eric Wolff
So, I have friends who are engineers who go and drill this ice forming using these, they look a little bit like very large wood boring instruments, but they drill out a cylinder of ice may be about 10 cm in diameter. We pull up 3 or 4 meters at a time and if you keep going and do that a thousand times, you get to the bottom of the ice sheet.
Interviewer - Chris Smith
And so how far back, if you get to the bottom that gives you how much time?
Interviewee - Eric Wolff
Well the oldest ice that we've got so far from ice cores in Antarctica is 800,000 years old. We think that there is older ice somewhere in and sometime in the rest of my career I hope we will get to well beyond a million years. But 800,000 years already takes us through 8 cycles of having ice ages and warmer periods, so it's already a very good range of climate.
Interviewer - Chris Smith
And how do you get the data out. So once you've got the chunk of ice, how do you actually find out what the climate was doing by analyzing that?
Interviewee - Eric Wolff
Okay, well, as you are employing its all chemistry, mainly we bring the ice back and some of the analysis is done in the field in Antarctica but mostly it's brought back in different sections that are sent to different labs around Europe in the case of the projects like mostly been involved with. The first thing that we measure is the isotopic content of the water itself. So that's comparing the amounts of water with oxygen with the weight of 18 and standard water with oxygen with a weight of 16 and that tells you what the temperature was at the time the snow fell. So that's really the very primary thing that you want to know, that keys everything else in. Then in addition, there are lots of impurities in the ice, for example, we can measure sulphuric acid or sulphate in the ice and it tell us lots of things, but one of the very obvious things is that you occasionally see very big spikes whether the concentration of sulphate goes up by may be a factor of 3 over the background and that's always because that was the year when there was a big volcanic eruption like Krakatau in 1883 and then finally we got these little bubbles of air that are trapped in the ice and those bubbles can be cracked open again and analyzed for all the trace gases in the atmosphere.
Interviewer - Chris Smith
And when you do this analysis, what's the message that's emerging; what are you seeing?
Interviewee - Eric Wolff
Well, there are different messages depending on the time scales you look at. The big one that comes after the long records is that you see climate warming and cooling over 800,000 years and the most striking thing is that carbon dioxide and methane, but carbon dioxide particularly go up and down as the ice ages go up and down. Our inference from that firstly is that they are playing a major role in amplifying what should be very small climate changes into big ones that can make ice sheets come and go. Of course, it's also telling us something about the carbon cycle and about how carbon dioxide is released from the oceans and from land at different times which is something we're going to really need to understand in the future as we want the oceans to mop up some of the carbon dioxide we're putting into the atmosphere. So it both tells us how carbon dioxide affects the climate and how the climate affects carbon-dioxide.
Interviewer - Chris Smith
Because some people have pointed out that we assume that this year too goes up and then the world warms up, but of course when you warm the planet, you warm the sea and if you've a warmer water, then less gas would dissolve in warmer water and as a result that would lead to CO2 coming out, wouldn't it? So how do we know that it's the CO2 coming first and then other effects secondarily.
Interviewee - Eric Wolff
Well actually in the past, it probably wasn't CO2 coming first, that's a very good point and worth making and these natural changes of several degree Celsius in global temperature that happened roughly every 100,000 years, we think it was almost certainly the small changes in the structure of the Earth's orbit around the sun that triggered everything off but then the carbon dioxide coming out soon afterwards amplified it helped in being a very big climate change. So you get this, as you say a chicken-and-egg situation where both the temperature and the carbon dioxide are rising together actually for several thousand years and the difference with what's happening now is that we don't have to say which came first, because we know which came first. We know we are putting lots of carbon dioxide into the atmosphere and that's another one of the very clear results from ice cores.
Interviewer - Chris Smith
When we compare CO2 levels now with what your record say they have ever been in the past, where are we now on the, sort of, grand scheme of things?
Interviewee - Eric Wolff
Well, we're much higher than it has been at anytime in the last 800,000 years. So it ranges between 170 in the cold periods and about 300 in the very warmest periods and right now we are at 380, 385 I think, this year and rising by 2 parts per million per year. So it's much higher than anytime in that period. There are very indirect measurements from ocean sediments suggesting that carbon dioxide was significantly higher 10 - 20 million years ago and then of course a lot higher back in the geological time, when the Earth was indeed very much warmer than it is now. So within the time period when the Earth looked like it does now, with the continents in the same places, this is probably the highest level but we only know about the last 800,000 years for sure.
Interviewer - Chris Smith
Sure, but when it has gone that high before, what actually turn things around to make it come down again, because that's a pretty important question for us, better answer it?
Interviewee - Eric Wolff
Yeah, that's a very good question and I don't think anybody has a particularly good idea on these 100,000 year time scales, we think what's happening is essentially the balance between what's in the deep ocean, what's in the surface ocean, and what's in the atmosphere has been changing probably due to changes in the way the ocean circulates. But over longer geological time, there is a balance between carbon dioxide being put into the atmosphere and taken out through volcanism on the one hand and weathering on the other hand and so that's determined by things like how bigger an area of mountain building is going on that causes weathering and things like that, which I have to say are beyond my limit, but they are certainly on time scales that aren't going to help us.
Interviewer - Chris Smith
So when it comes to global warming, it sounds like, we've got something of a mountain to climb, thank you very much. That's Eric Wolff from the British Antarctic Survey.
(Music)
Interviewer - Chris Smith
This is the Chemistry World podcast, with me Chris Smith and still to come, we will be finding out why heavy metals might be to blame for dolphins beaching themselves and we'll also be raising a glass and drinking the contents to beer photochemistry.
(14:30 -- Can humans sense light through their skin?)
Interviewer - Chris Smith
But first Victoria we've heard of people having eyes in the backs of their heads but now there is a possibility that skin almost has eyes of its own.
Interviewee - Victoria Gill
Well and this is the team of researchers from the University of Paris and they have found that proteins that are sensitive to light very similar to the light sensitive proteins that you find in plants that can kick start chemical reactions that tell a plant when to flower or when to unfurl its leaves. They're found in our skin. Now we've known this for a long time. But what wasn't known was whether they were actually light sensitive and whether they have any function.
Interviewer - Chris Smith
So what are they doing in the skin, do we know what they do there at all?
Interviewee - Victoria Gill
Well, we still don't know. This is very preliminary research and we still don't know quite why they are there, but this particular research group has discovered that they do respond to light which was something that was completely unknown. So what they did was they expressed these cryptochromes, these are light sensitive proteins, they reduce in response to light and at least they do in the plant version, so they took the proteins from human skin and also the fly version of this protein and expressed them in cells and then they exposed them to blue lights to which the plant's cryptochromes are very, very sensitive, very highly sensitive and they found, looking at them very closely with a very sensitive spectroscopic techniques, they found that indeed they do change. They photoreduce just like the plant proteins do and so what they have concluded is that there may be a function for these proteins, we may be sensing light through these proteins in our skin and that may be contributing to, say, our circadian clock, so that's the day and night rhythm that tells us when to sleep and when to be awake.
Interviewer - Chris Smith
Isn't that what eyes are for?
Interviewee - Victoria Gill
Well exactly, I mean, we know that we sense light through our eyes and that we have chemical reactions that are stimulated by proteins that are found in our retinas and we know very well that the circadian rhythms are linked very closely with those chemical reactions. So it's quite controversial, this research team haven't concluded quite what these proteins are doing, when they respond to light, just that they do and in fact we spoke to one researcher who explained that in humans who are blind and can't sense light through their eyes at all, those people don't have any body clocks, so they don't have a circadian rhythm, so we can only sense light through our eyes, this is what he was telling us. So it seems that we still haven't determined what the function of these skin cryptochromes is.
Interviewer - Chris Smith
There was a paper in Science a few years back, where they were experimenting that the idea of shining lights into the backs of people's knees on airplanes to try to reset the body clock, so they wouldn't get jet lagged and in fact it was found to be rubbish.
Interviewee - Victoria Gill
Right!
Interviewer - Chris Smith
And there is no evidence that light shown on skin can adjust the body clock, even though the paper in Science to start with, was subsequently disproved. So it sounds like this agrees with what your researcher told you.
Interviewee - Victoria Gill
Yeah, exactly and it still leaves these light sensitive proteins, they are a bit mysterious.
Interviewer - Chris Smith
Well, let us hope someone can shed some light on that dark mystery before too long. Thank you Victoria.
(17:32 -- How mercury could be responsible for Dolphins beaching themselves)
Interviewer - Chris Smith
Well, from a heavy question about lights to a heavy question about heavy metals, because there is a suggestion James, that this might be the reason that some animals like dolphins choose to beach themselves.
Interviewee - James Mitchell Crow
Well some Australian scientists have been looking at the connection between mercury poisoning and dolphins beaching themselves. And so a group at Monash University in Melbourne have looked at local pod of dolphins in Port Phillip bay just outside of the City of Melbourne and measured the mercury levels of apparently healthy dolphins swimming around in the bay and compared their levels with the dolphins who have beached themselves and subsequently died and have found that the beached dolphins have average mercury levels over twice that of the healthy dolphins.
Interviewer - Chris Smith
Is that throughout their body or are there any particular hotspots, like the brain for example, is this sort of a neurological effect?
Interviewee - James Mitchell Crow
Yes, the levels detected would definitely have neurological effect which would likely induce confusion and disorientation. So could potentially be directly leading them to beach themselves.
Interviewer - Chris Smith
So this is a, sort of, dolphin equivalent of the Mad Hatter syndrome.
Interviewee - James Mitchell Crow
Yeah, that's right, in the particular area that these guys have been researching in Port Phillip Bay there's lot of dredging work going on at the moment in the port which is sort of stirring up the sediment and potentially increasing the mercury levels in the water. The team suggests that the likely source of the mercury was the historical gold mines dotted throughout Victoria which have gradually washed down the rivers and ended up in the bay, in the sediment and eventually through the fishes that dolphins eat, accumulate in the dolphins. The teams are going to go on and look at historical mercury levels and try and establish whether this is an increasing problem. So then the next step that these guys are going to take is to, take teeth from dolphin samples in museums and check the mercury levels there. The other benefit of using teeth is that you know exactly how old the dolphin is, so you can determine how much mercury is accumulated over its lifetime, to try and establish whether the mercury levels are increasing.
Interviewer - Chris Smith
Well let's hope it will, thanks James.
(19:40 -- Malcolm Forbes, chemistry professor from the University of North Carolina, explains how chemical techniques are helping create the perfect pint)
Interviewer - Chris Smith
Now as you put it to me almost every scientist likes beer, which is partly why you became interested in studying it and how sunlight can affect the way it tastes. Here's Malcolm Forbes.
Interviewee - Malcolm Forbes
I have a special technique I have developed in my lab called Time Resolved Electron Paramagnetic Resonance Spectroscopy and it looks at fast photochemical reactions on the sub microsecond time scale that allows you to look at the structure of a free radical and the (UNCLEAR 20:06) structure looked at its reactivity, may be some of its molecular dynamics.
Interviewer - Chris Smith
And what do you think is going on when beer changes flavour in this way?
Interviewee - Malcolm Forbes
Well, what we believe happens is the hop compound, these are called the isohumulones these are the compounds that give beer its bitter flavour. They absorb light and once they absorb light they are in a very high energy state and they break apart and they break apart into something called free radicals, which people have heard of in the cosmetics industry that are responsible for wrinkles, for example in aging free radicals play a big part of the aging process, but these radicals in beer are trapped almost immediately by sulphur sources in the beer and they make compounds called thiols and thiols are extremely stinky compound; they are found in skunks; found in cat urine and that are almost anything that smells really bad has thiols in it and humans are very sensitive to these smells. So we wanted to find out what radical exactly were being trapped by these sulphur compounds and were creating bad smells.
Interviewer - Chris Smith
And so what did you do?
Interviewee - Malcolm Forbes
Well, Denis my collaborator at the University of Ghent sent us different types of hop compounds, some of them were of the natural variety, some that were chemically modified a little bit, the brewing industry uses to combat this problem and we put them in our spectrometer, we shined Ultraviolet light laser pulses on them and created free radicals and trapped these signals in real time and we determined their structure and we are able to say, Yes, indeed hop compounds produce free radicals and these are the radicals that are formed and this leads directly to an understanding of the mechanism, the formation of skunky beer.
Interviewer - Chris Smith
So now you know this, are
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