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CHASING THE DUST Oceanographic Expedition - LIVE! Diary, short films and school activities!
Tenerife, Canary Islands At Sea! The first few days are always a little tense as the instruments are being set up for experiments and sampling. Little by little it then becomes clear what is malfunctioning and what is missing. Unfortunately by then it is too late! The good news is that most of the equipment is working well, and we have forgotten only a few minor items. In cases like this, we have to be creative and improvise as obtaining chemicals or spare parts is impossible whilst at sea. Today the sea is quite calm. We have winds of force 3-4 on the Beaufort scale, what really is a pleasant breeze. From Tenerife we have been heading south. We have undertaken sampling at 4 stations so far, and will now be heading west for the next 2-3 days. Our heading is for 27° North, 30° West, into waters with extremely low levels of surface ocean productivity (oligotrophic waters). As I write this diary entry, we are cruising through waters which are influenced by the upwelling system off north west Africa. The upwelled (deep) water brings nutrients to the surface, sun-lit waters, which stimulate phytoplankton growth and hence the whole marine ecosystem. We will be sailing to the west of this system and will see the influence of the upwelling system diminish, as the ocean surface will become very blue with few planktonic organisms in the surface. We have a very nice group of young researchers on the ship. There are multiple nationalities represented, so we can all advise the cook on our favourite dish! The technical support on the vessel, and the ship’s crew and officers are also excellent; they are all trying to make sure that this cruise will be a great success. Time to check up on things! A day on the RRS Discovery
One essential instrument that is deployed at all stations is the CTD Rosette, a cylindrical frame with a range of oceanographic sensors attached, including salinity, temperature and depth sensors (CTD stands for conductivity, from which salinity is derived, temperature, depth), a fluorometer to measure in-situ fluorescence, an oxygen sensor and twenty-four 20 liter Niskin bottles. The rosette is bulky and weighs more than 1 ton! It is lifted from the deck of the ship into the ocean by a crane and a winch from the starboard (right) side of the ship (see ship plan) operated safely by the ship’s crew. Once the CTD Rosette is in the water, the sensors send data back to the laboratory, allowing oceanographers to look at detailed profiles of properties such as temperature, oxygen and fluorescence in real time. Here is the screen of the profile we saw this morning. Other instruments deployed at a typical station are a plankton net, marine snow profilers and optical sensors, but you will hear more about these throughout the cruise. At mid-morning, we finished the first station and head off for the second, planned at 1pm. The ship steams between station at almost full speed of 11 knots (11 nautical miles per hour). Scientists spend the rest of the afternoon and evening collecting more samples while the ship is moving, or analysing already collected samples in the labs on the ship. Work typically finishes between 8 and 10pm. Social events are sometimes organized in the evenings e.g. the quiz organized last night by Mark.
Living Conditions After personal space, the next important thing for comfort is the kitchen staff! They are very important on the ship. By the way, the kitchen on a ship is called ‘the galley’. For breakfast today, there is a choice of cooked English breakfast, including eggs, cereal and fruits. Lunch is a choice of soup, sandwiches, salad and pizza. Dinner is 'A La Carte'. Tonight we had a choice of soup or spring rolls for starters, and Thai curry with chicken or vegetables for our main course, followed by fruit and ice cream for dessert. There is always plenty of food on research vessels, which is great for keeping up everyone’s moral high.
................................................................................................................................. A sample every 30 minutes!
I am the Flow Cytometry Technician at the National Oceanography Centre in Southampton and my role is to study some of the very smallest, yet very important forms of life in the ocean - bacteria and the very smallest phytoplankton. People often question what the point is in studying things that are too small to be seen with the naked eye. People sometimes assume that as I develop my career as a biological oceanographer, I will be allowed to study bigger organisms like whales and dolphins! But that’s not how it works. Picophytoplankton (tiniest of plankton including autotrophic bacteria) are not only my passion, they are also a whole science in themselves. Though very small, they are vastly numerous that account for a great deal of the biomass in the ocean. Bacteria are the recycling centre for nutrients needed to support life in the oceans. Their size really misrepresents their importance! Many of them are important in taking up carbon dioxide, a greenhouse gas, out of the atmosphere. As there can be more than a million individual bacteria per millilitre of ocean water (don’t let this put you off swimming in the sea – most are harmless!) no other technique provide such an accurate, time efficient count of their abundance and biomass, as flow cytometry, which is my area of expertise.
The flow cytometer counts and identifies individual cells by passing them through a laser beam and detecting how they fluoresce and scatter the laser light. Different groups of phytoplankton and bacteria will scatter the laser light in their own very specific way. This individual signature can be used to calculate rapidly their density in the water, their role in the ecosystem and even the health condition they are in. Generally the lack in nutrients or stress conditions can deteriorate the health of these tiny organisms. On this particular cruise, I will be making my contribution to see how Saharan dust, and the iron it caries, affects the health state of these tiniest of phytoplankton. I am making seawater measurements every 30 minutes throughout the whole of the cruise. For a four-week cruise, that’s almost 1500 measurements! You may think this doesn’t leave much time for visiting the well stocked galley and bar, or for sleeping for that matter, but I have a loyal friend that gives me a break. I have a robot, which automatically takes my water samples for me 24 hours a day! Mmmm I wonder what’s for dinner! ............................................................................................................................... Cup of tea anyone? (Happy Birthday Uncle Trev!) I work in the same research group as Ross Holland, Flow Cytometry technician, who made the diary entry yesterday, describing the fascinating work we do with the tiny but so important marine bacteria and phytoplankton. I am a student in the group and it is my job to assess the welfare of these tiny creatures. I am most interested to find out how they like all this dust that is being dumped on them directly from the Sahara. For the purpose I do quite a complicated series of incubations involving radioactive isotope-labelled substances. By using these radioactive isotopes, it is possible to trace how much of a particular nutrient is assimilated by the bacteria, and this tells me whether they are happy and well, or struggling to survive.
Unlike most of the scientists on board, I don’t collect my seawater sample in a bottle, but instead use a thermos flask. Obviously, this amuses the others and I am often teased and asked for a cup of tea (being called Polly, this is something I am used to!). It is not very high tech but there is a good reason for using a thermos flask to collect my samples. The same vacuum in the flask that keeps your (and mine!) tea hot, ensures the seawater water sample remains at the same constant temperature, despite the blazing sun. The double walls also keep my bacteria in the dark so that they do not get confused or traumatised on their way to the lab. One of the best things about studying bacteria is that unlike those biologists studying big organisms such as whales or turtles, we don’t have to go far to find what we’re looking for. Every millilitre of seawater contains at least a million bacteria! These tiny bugs may be small, but put them all together and they make up around one-third of the Earth’s biomass. So, can you imagine what sort of an influence they can have on the world’s oceans! Catching the Rain
At this point may be I should explain that one of my responsibilitieson the cruise is the collection of rainwater samples. As soon as it starts raining, the officers on duty on the bridge will kindly let me know, just in case I happen to be sleeping as was the case. Trapping the Dust
We can also detect the Saharan dust in the atmosphere high above us using a small hand held device called a sun photometer. All I have to do is point at the sun and, provided that there are no clouds, I obtain a scan of all the wavelengths of light reaching me. This tells me the optical depth of the atmosphere, which is a measure of how many particles there are in the atmosphere scattering the light, i.e. how much dust is blown over us by the winds. What's on the menu, for phytoplankton?
The sunlit surface of our oceans is populated by small, floating single-celled algae that float with the currents, called phytoplankton. Just like plants, they require nutrients to grow, no different from the flowers in your garden. You may even add more nitrate and phosphate to help the plants grow better. The phytoplankton in the oceans also require nitrate and phosphate to help them grow. Certain phytoplankton, diatoms, even need silicate to construct their ornate shells out of pure glass. Unfortunately the waters around the Canary Islands tend to be pretty poor in nutrients (oligotrophic waters).
My job on board is to measure the concentrations of the nutrients nitrate, phosphate and silicate in the seawater and determine whether or not they are sufficient for phytoplankton. What also intrests me is at what depth these nutrients start increasing (i.e. at what depth phytoplankton stop growing!). Ultimately it is the phytoplankton in this relatively shallow surface layer that are at the bottom of the ocean foodweb and sustain the entire ocean ecosystem. In fact, given even the right conditions phytoplankton in the surface can ocean can change climate, so these small guys can have a very big impact! Even though automated, the routine can be long. I usually start at around 06:30hrs and can finish around 20:00hrs though I do stop for meal times. If I do manage to finish early though I can relax before going to bed by watching a DVD in the rather large TV room. Unfortunately we are too far from land to receive a TV signal so I can’t watch the football. Luckily we get the results on the ship via a daily news-sheet or via e-mails from friends and family back home. Keeping in touch with the outside world can be difficult, but regular e-mails help to make sure we’re never too far from home even though we are thousands of miles away. Sending a picture to the bottom of the sea
There is a lot of work to do on the cruise, but so far the atmosphere in the lab has been very relaxed. And it is important to see people on board smiling, even when things don’t always work out as we want them, especially on expeditions as long as 30 days.
As we send our instruments deep into the ocean’s belly, they experience a crushing pressure that increases with depth. A good way to demonstrate this is to put a polystyrene coffee cup on the CTD Rosette just before it goes in the water, and then send it to the bottom. Decorating the white cups before sending it to the bottom is a bit of a tradition. As they disappear from sight, the rapidly increasing hydrostatic pressure squeezes all the air out of the soft and spongy polystyrene. The result is that the cups come back very, very small. You can see on the picture the comparison of a cup before and after the deep cast. And this cup only went to 1800 meters! Imagine if it really reached all the way to the bottom! I am measuring two different parameters in my work. The first one is the pH of sea water. A pump brings seawater continuously to my lab from approximately 5 meters depth, and using an automated system I measure the pH every minute. That's a lot of data after a full month at sea!
The second parameter I measure is dissolved inorganic carbon, or DIC for short. Together pH and DIC can tell us a lot about the chemistry and biology in the surface, about the CO2 exchange between atmosphere and ocean, and ultimately how much more anthropogenic CO2 the oceans can absorb before the ecosystem is affected. In its extreme scenario, excess anthropogenic CO2 in the atmosphere will lower the oceans’ pH, a process known as ocean acidification. But may be it would be more fun to watch a film on that!
............................................................................................................................... A low catch I am onboard doing research on phytoplankton. Because phytoplankton use photosynthesis in order to extract the energy from sunlight to take up the carbon dioxide they need to grow, they can only live in the upper part of the ocean, down to around 100m or so. Light attenuates rapidly in water, and some of it is absorbed by the phytoplankton cells themselves. Besides light, like all organisms, phytoplankton also need certain nutrients in order to be able to grow. In addition to nitrogen and phosphorous, small amounts of iron are required. As phytoplankton grows in the well lit surface region, they rapidly reduce the concentration of these nutrients. This results in nutrient-poor conditions and consequently, certain regions of the world’s oceans don’t have large amounts of phytoplankton either. These regions are effectively deserts, and we term them ‘oligotrophic’. The region we are studying is towards the edge of one such dessert, known as the sub-tropical North Atlantic gyre.
As you may have already heard (and are likely to hear many more times if we actually do find a dust storm!), the concentrations of nutrients in the surface are so low in parts of this region that even small inputs of dust from the atmosphere supply desperately needed nutrients. However, in the case of one of the nutrients, nitrogen, there is another route for it to get from the atmosphere and into the phytoplankton. Generally phytoplankton cannot use atmospheric nitrogen as the nitrogen molecule is too hard to break apart, with the exception of one group of species, which are capable of extracting nitrogen from the atmosphere (really from the air which is dissolved in water) in a process called nitrogen fixation (or diazotrophy). You already heard from Ross and Polly about the very small organisms which are dominant in our region. Some of the organisms which perform nitrogen fixation are also very small. The most well known nitrogen fixing marine phytoplankton is called Trichodesmium. The individual cells of this organism are known to bind together to form quite large colonies (a few mm across) which are visible to the naked eye and at times can form very obvious slicks on the surface of the ocean. Unlike the bacteria and picophytoplankton which you have heard can be present in concentrations of 100s of thousands or millions per millilitre of seawater, we may only find a few Trichodesmium colonies in every litre of seawater. However, because it can be an important source of nitrogen, the occurence of this organism can be very important for the operation of the ecosystem in these oligotrophic ocean deserts. Because Trichodesmium colonies are so much bigger and rarer than the single celled phytoplankton, we collect them using nets. However, even by towing a net through many cubic meters of water we may still not find any and unfortunately today was one such day. We were luckier last week so later in the cruise if we find more I will send you some pictures. As well as doing experiments and making measurements on any Trichodesmium we catch, we are also measuring the rate at which nitrogen is fixed by this and other organisms. To do this we perform an incubation experiment where we control all the conditions while a certain organism is examined. In this case, we feed the organisms their favourite meal (nitrogen gas) only to be able to trace it, we label it with an isotope of nitrogen (15N) which is different to that typically found in the ocean. It is almost like giving Trichodesmium colonies a barium milk shake to trace how much free nitrogen they process! ............................................................................................................................... Finding my sea legs
I am also using two instruments on the cruise called the FRRF (fast repetition rate fluorometer) and FIRe (Fluorescence Induction and Relaxation) systems, which can show me how healthy the microbial cells in my samples are. This is useful as I can work out whether cells are damaged or stressed in any way due to the iron deficiency they experience or even as a result of me filtering them. After the filtering, it’s a mad dash for lunch (the two seem to always coincide). I spent the afternoon analyzing data from the FRRF and FIRe and preparing for another day of filtering on the RRS Discovery. This cruise is the first time I have been away at sea and thanks to the combination of the friendly group of scientists and crew onboard, the amazing food (I haven’t quite made it to the gym yet but I think I might have to before this month is over!) and the weather we have been getting, I am having a fantastic time! Got to go. ............................................................................................................................... Single cells, global consequences!
Believe it or not, although phytoplankton in the oceans are limited by nutrients (depending on region), or light (depending on depth, or region e.g. in the poles), they can have too much of a good thing. THE key ingredient for photosynthesis, light, can also damage them. And here, around the Cape Verde Islands, with all the beautiful weather we have been having, the sun is beating down on us. What we are trying to prove with our incubations on the deck is that phytoplankton can produce certain compounds to protect themselves from this high intensity sunlight, just like throwing sun lotion on themselves. Phytoplankton use various ways to protect themselves against light damage, or photo-inhibition. Some secrete shiny calcite shells to that reflect back excess light, other can even repair their damaged proteins. Coccolithophorids example are masters at this. They produce a compound called dimethyl sulphide propionate (DMSP), which is thought to have a number of different functions in the cell. One of those suggested is as an antioxidant to protect against damage from high light intensity. We are particularly interested in explaining how and why DMSP is produced by phytoplankton, because it breaks down to form a gas called dimethyl sulphide (DMS) which can have a significant effect on our climate.
DMS happens to be released when coccolithophorids are exposed to intense light and it also happens to promote the formation of clouds in the atmosphere. The net results is that the clouds could shield the coccolithophorids from the intense light that caused them to release the DMS in the first place. The beauty of it is that something as small and insignificant as a single cellular organism only 5 microns across can alter the atmosphere above it to benefit its own kind! The consequences however could be more than just a curiosity. Given enough of these single cells, and under stressed conditions, the enhanced cloud formation can significantly alter the global albedo and amount of sunlight that reaches the planet’s surface. The implications for climate long term can be significant, and we are only talking about single celled organisms here! ............................................................................................................................... Outside it is still dark... The morning instrument cast is also a good time for animal spotting as the ship is lit up with spotlights which attracts squid and fish. Yesterday I saw my first flying fish. It actually jumped right out of the water and landed on the deck. This one got lucky as I put it back into the ocean, but I am told that they taste pretty good so the next one better watch out! This cruise is dedicated to understanding the impact of Saharan dust on nutrients and biological productivity in the eastern (sub)-tropical Atlantic Ocean, and it looks like we just might get it soon. My own work is settling into a nice routine. Personally, I am interested in the optical properties of seawater and observing chlorophyll in the oceans both with instruments from ships and satellites in orbit. Dust in the atmosphere can play tricks with satellite observations, so I have to be aware how to correct for it.
Most of my previous work has been in the shallow seas (<200m) around the UK, which are close to land and often there is a lot of suspended material in the water. Particles in the water tend to make the water appear green or even brown in colour. Out here the water is clear deep blue because there is much less suspended material in the water. This means that sunlight can penetrate deeper into the water and less of it is reflected back into space. Despite that, by the time you get down to 100 meters, the red, orange, yellow, and green wavelengths of light are absorbed so that the remaining light we see is composed of the shorter blue and violet wavelengths. To study the absorption of light in the oceans I use optical measuring instruments to obtain vertical profiles of light with depth. We would love to get a big dust storm to chase after, but that’s not up to us. After a couple of weeks I think everyone is missing their families. It should get easier when the end gets closer, as it still seems quite far off at the moment. In the meantime I am enjoying the company of a great bunch of people and trying to make the most of every moment I get on the RRS Discovery. ............................................................................................................................... Dust! Finally!
The ship's officers and crew have been fantastic. Must also mention the engineers on the cruise. They are a cheerful bunch, and happily burst out in harmonious song. They are all making the cruise a success! Dust! Finally!
A satellite image of the top of the atmosphere (provided by Plymouth Marine Laboratory) is shown in the graph below and indicates that the dust plume was shrouded in the band of clouds. The aerosol collectors have been very busy over the past few days, and the filters have been orange-red from the Saharan dust. We will be using this dust in biological experiments, whereby we first rinse the nutrients off the filters and then provide this rinse water to bacteria and other microorganisms to observe how they react. Drifter deployment The drifter emits a signal to a satellite every 90 sec (Argos transmitter), and we reveive emails on the ship concerning the position of the drifter. We can then come back and observe the same patch of ocea. We will get back to it tomorrow and sample the waters there to see what has happened to the biology and chemistry after 3 days with very low dust inputs. Hopefully we can find the drifter again… it has a little light on top that will make spotting it easier at night.
Our heading now is back to the region of the Cape Verde Islands where we will sample the more productive waters. Following that we will head out west for a few days before making our way north to Tenerife via waters in the oligotrophic North Atlantic Gyre. Hopefully plenty of dust to come still! Stay tuned! .................................................................................................... A chain reaction
Most of the doors through the labs are water tight, to keep the water out of our working areas and living quarters if need be. That means big metal doors with high sills and thick rubber seals on them. More often than not, it is when I am mid doorway stepping over the sills and on one leg that the ship rolls under me and knocks me off balance! Quite amusing for anyone watching who is firmly planted on both feet! Besides this small problem, there is not too much on here to worry about. We are all very well looked after by the ship’s officers and crew, to such an extent that all we really have to worry about is our work. I am beginning to think of the good ship Discovery almost as a second home since this is the fourth time I am sailing on her since November 2006. I am a marine chemist at Plymouth Marine Laboratory and my primary objective on this cruise is to measure the response of iodocarbons in seawater to Saharan dust inputs. Iodocarbons are iodine containing gases which are in much higher concentrations in seawater than the air above it and therefore easily move upwards from the surface ocean into the atmosphere. So! Well, they are important because, once in the atmosphere, they can impact our climate. The sun splits them up into iodine atoms which then react with ozone (a compound made up of three oxygen atoms which protects the Earth from the Sun’s harmful ultra-violet rays). The free iodine atom acts just like chloro-fluoro-carbons (more commonly know as CFCs) and steals the one oxygen atom from ozone breaking up the molecule to form new iodine-oxygen compounds (iodine oxides). In turn, iodine oxides act as the starting blocks for cloud formation which affects Earth’s albedo (remember Ruth Airs’ story of plankton producing it’s own clouds? well, this is similar!).
The main link between iodocarbons and dust is again, phytoplankton. Iodocarbons have been shown to be produced by phytoplankton and therefore any increase in oceanic productivity due to a positive impact on the phytoplankton by dust, may also increase iodocarbon concentrations. If this were to happen, any potential impact on our climate would also increase. I think all this gives me a pretty good reason (and believe me, one is required) to get up before the sun every morning at 5:25am to sample the first pre-dawn CTD Rosette cast and collect my seawater for those iodocarbon measurements! ............................................................................................................................... Bouncing off the bulkheads This is my first time on board the Discovery or any other sea going vessel for that matter. I did not know how I would feel being on board a ship for a month; if I would suffer from sea sickness (I took some tablets just in case); never mind how I was going to carry out scientific experiments on a moving ship! (watch the video diary '30 days' of life and work at sea in the stormy Bermuda Triangle
I am researcher from the University of Essex. Whilst on the cruise I am working with Steve Archer and Ruth Airs from Plymouth Marine Laboratory. We are looking at phytoplankton photo-inhibition (damage to photosynthetic apparatus) by excessive and ultra-violet light. (see Ruth Airs blog to see how stressed phytoplankton can produce their own atmospheric clouds to shade themselves from the sun!). With the use of state-of-the-art instruments (Fast Repetition Rate Fluorometer and FIRe), we can determine determine how stressed the phytoplankton are and look for signs of photo-inhibition. We are also trying to identify recovery of damage to the photosynthetic apparatus through repair of the photosynthetic proteins (see also Anna Macey blog). So what is it like living onboard Discovery? The aspect I found the most difficult to get used to was the continual movement of the ship. I couldn’t sleep the first two nights onboard because I felt as if I was going to fall out of bed. Actually just yesterday morning, after getting out of bed, I only managed to walk half way across my cabin before I was suddenly thrown back in bed. I think it was a sign that 5.15am is too early in the morning to get up!
It is a strange sensation sitting in your lab swivelling chair and suddenly being spun around, first to the left, followed by a sharp change of direction to the right as the ship rolls. It can also be very amusing seeing people walking down the corridor towards you and then suddenly disappearing into a door way only to return a few seconds later and continue their journey as if nothing had happened. And it is definitely a test of balance, and a real sense of achievement to navigate the chairs and tables in the galley (where we eat meals) and reach your breakfast table without spilling the poached eggs on the floor. The labs aboard are just like our labs back at the university, only smaller. Despite working all the time we still have time to joke and laugh about life aboard. I didn’t know many people before I came on board, but feel I have made some new friends. ............................................................................................................................... “Riders on the Storm”
My task on the expedition is measuring iron in the dust and in the ocean (and we are now under an enourmous cloud of dust coming off Africa). As you might have already read, the trace metal iron has, due to its low concentrations in seawater, the potential to regulate the growth of microorganisms in many parts of the world’s oceans (read more on Ocean Iron Fertilization, CO2 and climate). However, the concentrations of iron here in the equatorial North Atlantic are on average a little bit higher than in other open ocean environments. We think that the reason for that is the millions of tons of Saharan dust that is blown into the ocean. So, we came to investigate whether that is true. The measurement of dissolved iron in seawater is a very precise job that needs constant attention. We do our job from a big and slightly rusty iron ship and we try to measure very, very low concentrations of iron. That means that we need all sorts of special equipment to prevent contamination of our samples. So just after breakfast, I and my colleagues Alex and Peter hurry to the trace metal clean container and dress up into our clean suits to prepare the arrival of freshly collected clean seawater samples. These seawater samples are collected with a special CTD Rosette that is totally made out of titanium and without any iron parts. The bottles of this titanium CTD are always cleaned with acid remove any contamination.
In an industrial container, specially converted into a portable clean laboratory, we prepare the seawater samples for iron measurements (also for manganese and aluminum). We also collect seawater from the surface but from a distance from our iron ship. To do that, we use a heavy painted metal torpedo that glides alongside the ship through the water. The water is then pumped via a sort of plastic garden hose to the clean container were we sample it. During our analysis, we concentrated the iron from seawater after which it is mixed with a chemical called luminol. The luminol starts to emit light in the presence of iron, so by measuring the light we can determine the exact concentration of iron. Every sample takes me at least 20 min, so in a working day that starts at 07:45h and ends at 23:00h I can measure on average about 25 samples! Since we collect about 25-30 samples a day, it is a constant race to catch up with work during the dust storm! ............................................................................................................................... Amino acids from the sky
As a student at the National Oceanography Centre, Southampton (NOCS), my interest is in amino acids. Believe it or not, rainwater and aerosols around me can contain amino acids, the building blocks of life! Where do they come from? Well, some of them have simply been ejected by the waves and spray from seawater into the atmosphere, but a lot them are carried over by the winds all the way from distant forest fires on land. The reason we care about even the miniscule amounts of amino acids, is that just like the Saharan dust (read more), they supply rare nutrients to the phytoplankton in the ocean around me. As amino acids travel with the winds into the atmosphere, sunlight slowly but efficiently alters their molecular structure causing them to release simple nitrogen compounds that phytoplankton can assimilate. As a result, biomass burning can affect ecosystems many thousands of miles away! This cruise is a fantastic oceanographic experience and I am having a great time working with the scientists, the officers and crew aboard. ............................................................................................................................... The end nears
Fresh fruit and salads are high on some people’s list of priorities. While the galley staff on board are still doing an incredible job of knocking out delicious meals three times a day, some of the more perishable foods are gone and the fruit bowl now contains only apples. Personally, having been confined to the ship for a month, I am looking forward to simply having the freedom to walk anywhere I choose. Higher up on my list of priorities, however, are several extremely long lie-ins. This is my fourth time at sea and each time I am taken aback by the wildness and remoteness of my surroundings. I find that I use my imagination more than on other occasions. Every day I look out the port hole, there is water as far as the eye can see in every direction. I feel like we really could be anywhere in the ocean and I wouldn't know any different. Only the GPS displays around the ship tell me that we are presently at 25° North, 28° West (which still doesn't mean very much to me, but at least I can look it up on a map!). The same displays also inform me that the sea-bed is a staggering 5585 meters beneath my feet! I find this very difficult to visualize.
The reason I am here is to study the dissolution of Saharan dust in seawater. As you have probably heard already, the huge clouds of Saharan dust that are flying high above the Discovery right now, can act as a source of nutrients (and trace metals) vital for phytoplankton growth in the open ocean. My work focuses on measuring which nutrients are coming from the dust and how much of them dissolve in the ocean. We have been very fortunate this cruise, and collected a considerable amount of dust on our air filters! I then use this dust to run my experiments, and together with the biologists on board we also do incubation experiments to see under controlled conditions whether dust is beneficial to phytoplankton, and how much. After all the experiments are done, I often take a cup of tea to the bow | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
In 2008 follow the SESAME cruises in the Mediterranean
We will be setting sail in 6 hours time. Everyone is busy getting their scientific equipment prepared and securely fastened so it will not fall over when the 
Our typical day starts at 5.00am, when the ship comes to a halt and we start our first station of the day at 5.30am. The Principle Scientist, Eric Achterberg, and other seniour scientists, coordinate the operation and plan where the stations will be and what experiments and activities will be performed at each station.
As eighth cruise on the RRS Discovery I feel I am in familiar surroundings now! It’s always enjoyable coming to sea, but this time, unlike most of the other cruises I’ve been on, the weather is a definite bonus! I’m used to working in much colder waters than these, so I’m enjoying the sunshine when I can get out of the lab!
Today was hot and sunny as usual - it’s hard to believe it is winter! This is my fourth research cruise in two years, yet it is the first time I have sailed aboard a British ship and so it’s a real treat to finally be understood by the ship’s 
Earlier today Eric, the Chief Scientist, asked me to make an entry in the cuise diary. I asked him what I should write about, and his answer was about my typical day and the aerosol sampling I do on board the ship. “All right” I said. Except, now that I think about it I don’t really have a ‘typical’ day! 
It is 15:00h (Greenwich Mean Time) as I write this entry to the Discovery diary and I am waiting for the 
We have been sailing for 10 days now and so far everything has been very pleasant. I am sure my colleagues already told you about the very comfortable living conditions aboard. And the weather! It is always a bonus to sail in good weather conditions. I am used to very rough conditions on cruises, when it is sometimes impossible for us to go outside on deck and do our work 
