Sunday, October 28, 2012

Another day, another drip

by Kim Cobb
We’re back! Well, that is, we’re back from a week at Camp 5, the rustic outpost about 20km from Mulu Park headquarters. After a 45min boat ride upriver, we hiked the last 8km carrying a week’s worth of food and scientific equipment, and 2-3 day’s worth of clothing. Camp 5 provides a roof, some gas burners, freshwater (even cold showers!), and mosquito nets, so provisioning is relatively easy. My undergraduate research assistant, Eleanor Middlemas, and I had just stepped off the last of 5 planes on our 70-hr trip from Atlanta to Mulu that very morning, eager to get going. Sang, a new graduate student at U. Michigan, had met us at the Miri airport, fresh from a 3-day battle in Hong Kong for a Malaysian visa.
We arrived at Camp 5 very worse for the wear, in the midst of a true Mulu-style downpour, happy for the jungle oasis. The rest of our group, comprised of graduate students Stacy Carolin and Jessica Moerman and undergraduate Danja Mewes, had been caving with long-time collaborators and guide-extraordinaires Jenny Malang and Syria Lejau that day. They arrived mud-coated and exhausted, but full of stories from Whiterock Cave, our primary target for the Camp 5 research. The next day, we hit the trail at 7:30am after some wonderful Nescafe 3-in-1, and reached the Whiterock entrance after 2 hours of hiking and 4 stream-crossings. Once inside we went to work collecting dripwaters from the stalagmites we had cored on the 2010 expedition. Jessica, Syria, and I pushed farther into the cave, finding an incredible chamber full of HUGE stalagmites (some no thinner than my arm but more than 20’ tall). The British cavers who first explored Whiterock had given us their maps for this expedition (map? who needs maps anyhow?!?) had named this chamber the “Nightwatchmen” for the carbonate sentinels watching over us. There were many broken stalagmites strewn across the floor, most of them too large for us to pack out. We took some hand samples for dating, mostly out of curiosity. My lab’s work on climate reconstruction is focused on the very recent geologic past – the farthest back in time we go is 140,000 years. While heading back through the sticky mud that coats the cave floor, the sole of my shoe came unglued!! and I had to use my shoelaces to try to lash it on as I limped back to the rest of the group. Jenny did some emergency duct-taping upon our arrival, which worked great. We rounded up the rest of the crew and headed out. I’m not going to lie, it was a miserable trip back – over 2.5 hours of limping through the jungle (most of us had developed some pretty good blisters by now) to arrive at Camp 5 after dark. Syria’s birthday dinner was a welcome distraction from our aching bodies.
The next morning we tackled Cobweb Cave – a comparatively easy hike in but a dismal cave to navigate, full of huge break-down boulders the size of a house, and full of disorienting twists and turns. A few years ago some nestors (locals who poach cave swift nests to sell for the equivalent of ~$2-3 each – a small fortune around here) had gotten lost in Cobweb for 3 days. When they found them they had already laid down in the graves that they had dug for themselves. Yikes. Luckily we had not one but two expert cave guides with us, but it is even more important to stick together while doing our research activities in a cave like Cobweb. After a relatively easy day at Cobweb (we do not explore past a certain point, because we need ropes to traverse a huge 50-ft hole in the floor), we arrived back at Camp 5 to see that my brother Niko had arrived. When he hadn’t arrived at Mulu with us, we had assumed that he wasn’t able to make it after all. We all took a swim and gave our bodies a rest, in preparation for a long day at Whiterock the following day.
Our last caving day was a full one indeed. Niko took some great footage of the scientific operations (see the video!), so we’re excited to get back and become YouTube sensations.  ;)   We celebrated Stacy’s birthday back at Camp 5 with a blow-out dinner complete with pineapple curry, green mango sauce, chicken curry, and a Dutch pineapple dessert. It was a jungle-sourced extravaganza that none of us will ever forget. 
video
We slept in yesterday, before hiking out of Camp 5 back to Park Headquarters. Two porters carried about 150 lbs of rocks out – I have no idea how – and we left all of our extra food, including about 100 Cliff bars, so our packs were light, if our hearts were heavy. Leaving a place like Camp 5 isn’t easy, even if you are heading towards hot showers and cold beers in the near future, and loved ones in the not-too-distant future. Back at Headquarters, I am grateful for a safe trip to the remote caves at Camp 5, and for the extremely hard work that everyone did towards accomplishing the lab’s scientific goals. We sure have our work cut out for us over the next years! Jessica, Stacy, and Danja will be staying at Mulu for another 10 days, while Eleanor, Sang, and I will be jetting back to States to complete our busy semesters. Class?!? What’s that?

Friday, October 19, 2012

Entry


Today is the third day that we have been in Mulu. In my last sequence of Caltech posts I chose the theme throughout to be trying to teach the advanced chemistry used in my thesis work to readers with little-to-no math and science expertise. For this trip my new idea is to treat each post like a journal entry, which can uniquely provide a personal window into the around-the-world fieldwork that we are doing. Hope you enjoy.

Friday, October 17, 2012

Woke up at 6:30am. Jessica was setting up her rain gauges as I went into the research center and began separating out what we needed to pack for today’s trip to a decorated chamber within Gunung Mulu. Small 4ml vials and funnels to collect drip waters, flagging tape for collecting broken stalagmites on the cave floor, lab notebook, lab camera, ect. We covered our bodies in insect repellant then walked over to the park’s restaurant to eat breakfast. Pancakes, fruit from the jungle, tea. Then we went back to the research center, grabbed our cave packs, quickly threw in our caving kneepads, gloves, helmets, and rubber shoes, and went out to meet Syria at the boat dock.

Beautiful 15-min boat ride down the river to arrive at the Cave of the Winds. We collected a few drips at the entrance -- a fun sight for the tourist groups as they shuffled past with their park guides into the show cave -- then followed Syria off the visitor's path and into the deep chambers of Gunung Mulu.


It’s been four years since my last time adventure caving with Syria here in Mulu, and I still love everything about it -- the mind-blowing gigantic chambers, the non-stop rock climbing, the slippery muddiness, the darkness, the nervousness, the adrenaline. But it’s Syria who makes the caving incredible. She is a god-- there is nothing she doesn’t know or can’t do, and I am in constant awe. Plus she is hilarious and fun. I have looked forward to seeing her again ever since I left four years ago. One of my few idols and an amazing friend. At one point while we were walking to the next chamber she stopped suddenly. “Stacy! Come here!” How nice -- she found a 6ft long racer snake gliding along outside the path to show me. She sees everything! I’m amazed. 

We arrived in the decorated chamber after about 2 hours of climbing. Sat down, ate some clif bars, then separated out to start our fieldwork for the day. I started searching around the chamber floor for some attractive broken stalagmites. I found a few, and carried them back to our lunch spot. Then I set up a 1-liter bottle on top of a tripod over a growing stalagmite to collect a large sample of dripwater to measure its trace-uranium concentration. Syria disappeared off to explore more of the cave chambers and look for new stalagmite decorations we hadn’t studied before.

At 3:00pm it was time to begin our trek back through the cave and catch our boat back to park headquarters. Covered in mud and sweat, the boat ride back in the rain was refreshing and fun. We showered, then went to the park restaurant to eat dinner. Laksa, jungle ferns, Milo. It was 7:00pm, but had already been dark for a few hours, and the rain was pouring. We returned back to the research center exhausted. I lay on the bed for a quick nap. Alarm set for 30 mins. I woke up at midnight.







Journey to Borneo!


After loading three chests full of scientific equipment (and at least a million clif bars!), four packs of personal gear, and a slew of carry-on bags into two cars, our journey to Borneo was finally underway. In spite of reminding our second driver to be sure to take I-75 to the new international terminal of the Atlanta airport, I proceeded to take the old route to the airport via I-85, as muscle memory took over. Correcting this added an additional 20 minutes to our journey, but we made it to the check-in counter with plenty time to spare, so all’s well that ends well! The first leg our journey was a 15-hour flight to Seoul, South Korea, which departed on Sunday Oct 14 at 12:30 am EST. Thankfully, we were all able to get a decent amount of sleep during the flight. We arrived in Seoul on Monday Oct 15 at 4am local time, and stared a 12-hour layover in the face. This was made more bearable since we booked a hotel room near the airport and were able to sleep for several hours. We certainly crashed hard! Eventually we managed to pick ourselves up and explore a little bit of South Korea by train before heading back to the airport for our 6-hour flight to Kuala Lumpur, the capitol of Malaysia. We arrived in Kuala Lumpur at 9:55 pm local time, a little less travel weary than before, but we were very thankful for our beds once we checked into our hotel. We spent all of Tuesday October 16 running necessary errands around Kuala Lumpur, like picking up our federal research passes and buying food for when we are at the remote Camp 5. But along the way were able to see many of the sites of the city, including Kuala Lumpur’s huge twin towers! We were also asked to pose several times in photos with other tourists, which was a little strange but made us feel a bit like celebrities! After completing all our official tasks and taking in a few of the sites, we were back at the hotel for our last night in ‘civilization’. At 8:30 am local time on Wednesday Oct 17, we finally boarded a flight headed for Borneo and Gunung Mulu National Park. After a quick stop in Borneo’s coastal city of Miri, we hopped on a puddle jumper plane to Mulu and flew over the rainforest. More than 72 hours after leaving Atlanta, GA, we were finally at Mulu. It was a pleasant surprise to find park manager Brian Clark waiting at Mulu airport to take us and our dozens of bag to Mulu park. After settling in at Mulu Park’s research center, we were ready to start the next leg of our expedition – the science!

Sunday, October 14, 2012

Galápagos Adventures


Weather monitoring at one of our sites
by Jessica Conroy
Hello from the Galápagos, where I’m in the midst of the second leg of my water-sampling journey, following my adventures in Kiritmati last May.  Again I’ve hitched a ride on a paleoclimate project, this time with my graduate advisor, Jonathan Overpeck, long-time collaborator and mentor, Julie Cole, and UA graduate student and good friend Diane Thompson (who you may remember from Kiritimati). It’s a great group, and we’re doing some really exciting science!

I have been working in the Galápagos since I was a baby graduate student, back in 2004. My ultimate goal is to try to understand long-term climate change and climate variability in this region.  There are very few climate observations, like precipitation and temperature, for the 20th century from the Galápagos. Thus, we don’t know much about long-term changes in climate here. And it’s important to understand how 20th century climate was different (or similar?) to past climate, since what goes on in the tropical Pacific can ripple across the atmosphere, influencing climate in many parts of the world.

About to begin the climb down to Genovesa Crater Lake
My graduate work focused on finding the climate signal in Galápagos lake sediments. I’ve found that I can match my more recent lake sediment measurements to the limited climate measurements in the region over the last 50-100 years. This is a super cool approach, not always done in the field of lake science, that can really enhance our understanding of the climate histories we reconstruct from lake sediments—less arm-waving, you could say. But, many questions and uncertainties remain, and there is much more work to be done.

La Pirata, our home for the week.
My postdoctoral work takes up the challenge of better understanding climate signals in lake sediments and in other paleoclimate proxies, like corals. I’m focused on understanding the links between the stable isotope values in seawater and rain and local and large-scale climate. 

 This means I’ve been taking lots of water samples all around the Galápagos—off our awesome boat, La Pirata, from the black shorelines of volcanic rocks, and from some pretty sweet beaches. Life is tough.

Trying to stay clean at El Junco, an unlikely prospect.
Unlike Kiritimati, it’s barely rained here, since it’s the peak of their dry season. However, we did notice as we ventured to a special lake called El Junco into the cloud-covered highlands that it was wet wet wet, with lots of mud to go along with all the misty rain. It was wetter in the highlands than last time I was at El Junco, in 2004. Is this part of a trend? Or just the interannual variability at this elevation? Hopefully I’ll have a good answer to that question soon!

The Princess – she keeps me up all night!

by Hussein Sayani (@hsayani)

Scientists will often name instruments and equipment in the lab. I like to think it’s out of pride and love, kind of like how people name their cars, and not because we talk about them all the time and just want to blend in with normal people waiting in line for coffee. For example, our Delta V plus mass spectrometer and Kiel carbonate device are called Matilda and Damien (named after certain movie characters). My friends know this, so I’ll occasionally get calls that essentially go: “I haven’t heard from you in a while. How’s Damien doing?” See, it makes us sound normal! Anyway …

The NENIMF houses two ion microprobes, the Cameca IMS 3F and the Cameca IMS 1280. For this project, we’ve been using the IMS 1280, a very large beastie affectionately known as The Princess.

The obligatory glamour shots

A quick rundown of how this ion microprobe works:
Schematic of the IMS 1280, borrowed from the NENIMF site.
A duoplasmatron (a type of ion source) is used to generate a primary beam of oxygen ions.  This primary beam then digs into the sample, ejecting ions from its surface (this is called sputtering).  Various lenses and deflectors are used to channel the sputtered ions towards a large magnet which separates the ions by tiny differences in mass (every element has a different mass).  After being separated, our charged particles are sent to the ion counters which tell us how much of each ion is present in the sample.  Pretty nifty, right?  For my samples, the measurement process takes about 15 minutes per spot.  We measure about 60-65 spots a day and the sampling is only partially automated. Hooray for 17 hour work da … wait, what?

The Princess and her bling:
Preparing samples for The Princess is a little different. With the other analytic techniques we employ, we usually mill some coral powder and then dissolve it in acid. The Princess on the other hand, prefers smooth, flat, and shiny gold discs. SIMS samples are prepared by cutting of a small section from the slab. The coral skeleton is very porous, so the side of the coral section that we want to measure is embedded in epoxy to create an even surface. After some polishing to completely flatten and smooth this side, a small slice is taken and attached to a glass slide with more epoxy. Then come the hours and hours of polishing the slide to get it perfectly smooth and flat. Finally, the slide is coated in gold (ooh shiny!). 

The thin sections (slightly larger than a quarter) are locked into a steel mount and loaded into the SIMS (red arrow).

Since the slice of coral on the slide is very thin (hence the name thin section), we can use a microscope shine a light through it and see the various different crystals that make up the skeleton. Besides being very cool, this lets us know what features within the skeleton to avoid (as different features have different chemical compositions).

The left side is what we see on the SIMS. The right side is what the slide actually looks like.
You need a map of both to know what to avoid (e.g the black line running down our column - see the white arrow).

I'm sorry, Earth!
Loading the sample into the SIMS and waiting for the instrument to reach high vacuum can take a couple hours, so it’s best to know beforehand where you want to make your measurements. After spending some time familiarizing myself with each slide (and series of slides as we have 2-3 per coral), I use the microscope to build a map to help me navigate each slide. Back in January I did this using paper, scissors, and tape (and you thought science was complicated). Out of kindness to trees and the planet, this time I made the maps on my laptop instead.


Now that we’re all familiar with the SIMS technique, let’s take a look at what this beastie can do. We’re interested in figuring out past ocean temperature, and so we’ll be measuring the ratio of strontium to calcium (Sr/Ca) at each spot on the coral as this is a commonly used  proxy for such reconstructions. Remember, our goal is to determine how useful, reliable, and reproducible SIMS measurements are. So the first thing we want to check is whether or not our SIMS measurements look like temperature. We measured Sr/Ca at almost weekly resolution (one measurements every 6-8 days). As you can see on the graph (light red line), the data looks very noisy and it’s hard to see any long-term trends. What we want to see is an annual cycle (a warm summer period and a cool winter period), and to get that we’ll have to do some averaging.  Since we’ll be comparing these Sr/Ca measurements to monthly ocean temperatures, a monthly running average is appropriate.  Applying this to the data set, we get a Sr/Ca record that happens to look a lot like temperature (thick red and black lines)! This is great because it tells us that we’re doing something right.


We still need to test how reliable this technique is – i.e. can we measure similar samples and get the same numbers? To test this, we measured samples from different corals that grew at the same time.  The idea is to get the same Sr/Ca record for each of them.  Surprisingly, the records from two of these overlapping corals were an almost 75% match. That is much better than what we were expecting.

There is much more data left to analyze, but it looks very promising. We’re hoping that the 800 measurements we’ve made will provide us with a roadmap to the most efficient and effective way to use this technique to test the integrity of our fossil corals.

Wednesday, October 10, 2012

Every coral has a story

by Hussein Sayani (@hsayani)

I like to think of paleoclimatologists as detectives trying to solve a mystery, which in our case is how the tropical Pacific climate has changed over the last thousand years.

Our research sites - the Line Islands in the central tropical Pacific

An example of a core taken from a Porites coral growing near 
Palmyra Island. X-ray images (right) are usually used to help 
us figure out where to make our measurements.
Satellites have only been measuring climate for the last couple decades.  So we need to somehow figure out what happened hundreds of years ago. That’s where corals come in. Reef-building corals (these are the large stony types) continuously form a hard calcium-carbonate skeleton. The chemical composition of each “layer” of skeleton the coral makes will depend on things such as temperature, how much it rained, ocean circulation, etc.  By measuring how the chemistry of these layers is different in the past, we can figure out how climate was different in the past.  And so, ladies and gentlemen, we have our “eyewitnesses”.

Paleoclimatologists typically extract climate information from corals by measuring the changes in elemental composition (usually calcium, strontium, and magnesium) and/or changes in the type of oxygen atoms present.


As climate detectives, we always have to question if the coral is telling us the truth.  In most cases we can trust our coral’s testimony, but occasionally our witnesses’ memory can become a little fuzzy.  This can especially be a problem when our witnesses are very old (i.e fossil corals). We of course thoroughly screen all our fossil corals and remove the bad ones, but we have to face that fact that there is no such thing as a perfectly preserved fossil coral.

The surface of pristine coral's skeleton is usually very smooth (left panel). Sometimes additional 
crystals will form on the skeleton's surface as the coral sits in seawater (right panel) or when a
fossil coral sitting on a beach gets rained on.  These features are invisible to the naked eye, but 
can be seen using a scanning electron microscope. 

The sharp needles covering the coral in the image above are one flavor of alteration (or diagenesis) that a coral skeleton can undergo. This diagenetic stuff, has a very different chemical composition, and can easily contaminate our samples making our climate reconstructions very wrong. The upside here is that in many cases, the diagenetic stuff is just lining the outside of the coral skeleton and the inside is usually not altered. So what we need is a way to pick what we’re measuring - something we can’t do with our usual analytical techniques.

Enter the SIMS! 

The ion microprobe lets us make very, very small measurements on coral.  Using this technique, we can measure spots on the coral approximately 10-20 microns wide.  This is less than half the thickness of human hair, and over 50 times smaller than the spots we usually measure on coral. Are you excited?  You should be!  This means we finally have a way to measure only the good parts of bad coral and still get reliable climate information. 

SIMS hasn’t been widely used in coral work so far, thus we’re in slightly unchartered territory here.  So the first order of business is to convince ourselves that SIMS coral measurements are reliable and reproducible (i.e. that we repeatedly get the truth from a coral that isn’t lying).  This is what I'm currently investigating at WHOI.

Up Next:  The 411 on SIMS.

Tuesday, October 9, 2012

To The Cape!

Hello readers, this is Hussein reporting in again. You may remember me from the Christmas Island Field blogs posted during the summer. As I forgot to introduce myself earlier, here is a little bit about me. I’m a third-year PhD student working in the Cobb lab at Georgia Tech. As part of my thesis, I’m working on using corals to figure out what tropical Pacific climate did over the last thousand years.  

Beach Breeze Inn, Falmouth MA - January 2012
Going back to research-related travel, one of the major perks of being a scientist is being able to travel to some very cool places (e.g Christmas Island). Why spend insanely long hours hidden away in a lab at home, when you can spend equally long hours hidden away in a lab somewhere totally new. I like to think of it as a “workcation” … it’s just as much if not more work, but somehow ends up being more fun. Most of the time.

A three hour plane ride from Atlanta and quick 1.5 hour drive away from Boston lies the sleepy little village of Woods Hole, Massachusetts - home to marine science powerhouses such as the Marine Biological Laboratory and of course the Woods Hole Oceanographic Institute (WHOI). I recently had the opportunity to spend another exciting two weeks at the National Northeast Ion Microprobe Facility (NENIMF) located at WHOI. NENIMF houses two secondary ion mass spectrometers (typically referred to as either SIMS or ion microprobe).

Vineyard Sound, Massachusetts - January 2012 
Over the next few days, I’ll be taking advantage of the brief lull in stalagmite related blogging to talk a little about corals, and the very cool science we’re doing with the SIMS, without getting too nerdy (so that my readers, i.e. mom and dad, can finally figure out what on Earth I do).

Wednesday, October 3, 2012

Dating -- so how old are you really?

by Stacy Carolin

Data data data!!! Much apologies for keeping everyone waiting!

Let's just remind ourselves of what we we're looking for so we know whether to be excited or sad when we finally get these dates :) I want to find stalagmites that formed during the Eemian period. This is why: Technically, the earth is currently in an "Ice Age" and has been for the past 2.5 million years (Antarctica is covered with ice as we all know). But "Ice Age" climates vary between "glacial" states (90% of the time) and shorter "interglacial" states (warmer and less ice, like today). These fluctuations are due to astronomical cycles (solar energy and orbital variations), the composition of the atmosphere (greenhouse gases), and changes in ocean currents. The interglacial state we are currently in is called the Holocene, which has been surprisingly stable for the past 11,000 years. The earth's last interglacial state was the Eemian, which began about 130,000 years ago and lasted for about 10,000 years. For many reasons (see previous post) it would be great to know how these two individual warm interglacial periods compare. So we are looking somewhat blindly for stalagmites (our time capsules of tropical climate knowledge) that formed throughout the Eemian period (130,000 to 120,000 years ago).

Below are the best-guess stalagmites that I chose to try to date for this project. These are scanned images of the "slabs" that I talked about slicing in previous writing. The tops will be the youngest, and the bottoms the oldest, since stalagmites grow from bottom up over time. The arrows show where I drilled out my sample.


Data collection from the ICP-MS is incredibly complicated and complex, and not very relevant here, so I am not going to discuss. I will just share the final counts of each element that we were looking for (U-238, U-234, Th-230) in each of the samples, which we will assume I calculated correctly from the ICP-MS output data. Notice how many more U-238 there are in all stalagmites (which is the most abundant uranium type found naturally because it has a half-life of a whopping 4.5 billion years! Recap: U-238 decays into U-234, which then decays into Th-230, which then decays into another element... that's why they are all technically radiogenic.)  Th-230 are the smallest in number (Th-230 has a half-life of only 75,000 years), thus any Th-230 contamination from dirt/mud will likely cause the most error in our ages.


In order to calculate the age, we use the measured values in the table above to solve a set of three first-order differential equations that model radioactive decay for a parent -> daughter -> grand-daughter system. To prove that this actually works, below is a picture of every age I've calculated on 4 different stalagmites that grew during the past 100,000 years (total of 92 dates, wow! drilled out, taken through chemistry, then run on the ICP-MS in 12 separate batches at Caltech over the past few years). And to my amazement, these ages have all come out in the right order (top is the youngest, bottom is the oldest)-- I am quite proud!


Hopefully I've convinced you that this process is very reliable and that I am capable of calculating the correct ages from the samples that I drilled. Ok, so now we are ready for our ages! Check them out (ages are in bold, absolute error is listed below):


Yay, now you're a scientist! What do you think? What are your thoughts? First, look at SC02! Based on these dates it grew 145mm (that's about 1/2 ft) in less than 1,000 years! That's incredible! The average growth rate of a stalagmite is usually between 5-20mm per 1,000 years (if we believe those dates-- I would like another few to prove it for sure.) Sadly though, it turned out to be too young for the Eemian period. And same for SC03. Darn it! Although because that 124,901 yr old age was not drilled at the very bottom, I can drill another date lower and hope we reach before 130,000 years ago for the oldest possible date. And unfortunately, SC12 turned out to be way too old. Oh well, he's out.

So what do we do from here? Sigh, all that work, and I still desperately need more samples, there's no way I can learn about the Eemian period if I only have half of it represented with one lonely stalagmite. It is best to have at least 3 records so that I can compare the results and make sure they are all reproducible. So, happily, it's time to go back to the caves (in Malaysian Borneo!) and collect even more fallen stalagmites, and hope that a few that I bring back just happened to have grown during the past 115,000-135,000 years.



Hey what a coincidence! We are headed to Borneo in less than two weeks! And then back to Caltech. YES! Stay tuned :)