A Glimpse into the DIC Lab: An Interview with Dana Greeley

Author: Kathryn Williams

The sea was angry that day, my friends – like an old man trying to send back soup in a deli. So I went to talk to Dana Greeley about DIC… Here is that “conversation”.

Kathryn: What is DIC?

Dana: DIC is an acronym that stands for Dissolved Inorganic Carbon. It is also referred to as Total CO2 (carbon dioxide). It is the sum of the dissolved carbonate species in the seas: carbon dioxide, carbonic acid, bicarbonate, and carbonate. DIC is a key parameter when making measurements related to pH and carbon dioxide flux estimates.  But do most of the readers of this blog really want to hear about this? Can’t we talk about the nice sunsets we’ve had recently? Here give them the link to DIC from Wikipedia. Then we can use your blog post to talk about something more entertaining.

Sunset on the Indian Ocean from the NOAA Ship Ronald H. Brown

Kathryn: OK then, when did you start sailing and why do you still go out to sea to measure DIC?

Dana:  A few of my favorite literary quotes might explain my motivation: “Of all the things that drive men to sea, the most common disaster, I’ve come to learn, is women.1” But that was not the case with me. “If you really want to hear about it, the first thing you’ll probably want to know is where I was born, and what my lousy childhood was like, and how my parents were occupied and all before they had me, and all that David Copperfield kind of crap, but I don’t feel like going into it, if you want to know the truth.2” “Some years ago – never mind how long precisely – having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world.3

Kathryn: OK, alright, hold it right there! Back to the interview… How do you measure DIC?

Dana: Aarrgh, alright. But you’re going to lose your readers if we go into this full on. Send the scientists to read The Handbook and I’ll give you the layman’s version here. We collect seawater from each niskin and take those back into our 20’ shipping container that has been modified as a sea-going laboratory. Inside that lab we hook up the seawater sample to our equipment and withdraw a measured volume. That volume then drops down into a test tube shaped piece of glass (stripper) where we add a small amount of dilute acid and bubble CO2 free air through the seawater so that it resembles a nice freshly poured glass of Fresca. You know what a Fresca is don’t you Mr. Scholarship winner? The (stripped) gas from that Fresca is then sent to a cell (picture a glass beaker with side arm) which contains a blue pH reactive solution that turns clear with the addition of CO2. The cell sits in an analyzer (coulometer) which sends a light path through this (blue) solution and on the other side sits a detector which collects the light and counts the coulombs and with some additional bells and whistles we determine the total CO2 (aka DIC) within that seawater sample. You’re losing your readers here. Seriously, if you want to know more, read the Handbook.

DICE system
DICE: Dissolved Inorganic Carbon Extraction. System used by the DIC Lab to extract DIC out of water samples

Hey, did you know the captain spotted a falcon back a week ago? Turns out it was an Amur Falcon, late returning migrant to its breeding grounds.

Amur Falcon
Amur Falcon on the NOAA Ship Ronald H. Brown

Kathryn: OK, back to the interview… Why are you out here measuring DIC; what is it used for?

Dana: Knowledge is Power! More data means more knowledge which yields a greater understanding.  These GO-SHIP cruises are a continuation of the CLIVAR/WOCE lines and this repeat hydrography helps to improve our understanding of the ocean carbon cycle and how it is changing over time. Data from those previous hydrographic cruises show that the ocean is not evolving with smooth decadal trends. Therefore we need to continue to go to sea to make these carbon measurements until an Argo type float can replace us humans. The old saying still holds true, “Don’t send a buoy to do a man’s job.”  Our DIC analysis helps climate scientists study climate change and predict future climate states with different climate scenarios. Speaking of, can you believe how hot it is outside today? I wish we could package up this heat and save it for the next time someone back home says, “It’s really cold outside, they are calling it a major freeze, weeks ahead of normal!”

Any last comments?

Yes, did you know we have now crossed into the Arabian Sea? It will be interesting to see what the Oxygen Minimum Zone holds in store for us as we continue north. I expect it will be a CO2 maximum, but that’s why we come to measure.

1 Charles Johnson, Middle Passage

2 J. D. Salinger, The Catcher in the Rye

3 Herman Melville, Moby Dick

The Biome Beneath the Surface

Author: Victoria Coles

Inhaling and exhaling, the ocean trades gases with the atmosphere; carbon dioxide, oxygen, chlorofluorocarbons and more. Different scientists on IO7 measure each of them. But what happens to the gases away from the sea surface? In the sunlit ocean, phytoplankton busily use energy from the sun to create more oxygen gas, and to convert carbon dioxide gas to plant mass. Equally active are the bacteria and animals who devour the plants as well as each other, respiring, or turning carbon biomass back to carbon dioxide while using up oxygen. The water here all looks blue to us (Fig 1).

Figure 1: Different shades of blue ocean on IO7.

From one day to the next there might be more or fewer whitecaps or torrential rain or fierce sun, but the water looks the same. Below the surface however, there is a hidden world with huge variability in plants and animals. Recently, we have begun to learn that the specific types of plant and animal food webs affect how gasses are processed in the ocean. So, we expect changes in the ecology to influence how much carbon or oxygen the ocean stores, and how much it passes back to the atmosphere.

And this brings us back to how we measure the plant and animal world at and beneath the ocean’s surface.  In the Bio Lab on the ship, Hannah Morrissette (MS student at University of Maryland Center for Environmental Science) and I are working with collaborators (Greg Silsbe, Raleigh Hood, and Joaquim Goes) using funding from NASA to understand the plant and animal communities that lie at the surface where satellites can see them, as well as below where they cannot. This is Hannah’s first time at sea, and I am continually reminded of how lucky we are to be here by experiencing this adventure through her eyes. For NASA, the satellites are our eyes; they measure the wavelength of the light reflected from the sea surface, then convert this to measures of chlorophyll content that can tell us both how many plants are present (Fig 2) and how fast they are growing. These are key measures of the health and state of the ocean, used for managing fisheries (like the tuna industry here in the Indian Ocean), as well as for understanding changes in the ocean’s exhalation of oxygen and carbon dioxide.

Figure 2: Ocean chlorophyll-a composite map using NOAA VIRS and NASA MODIS satellites. (Credit: Dr. Greg Silsbe)

But the satellite measurements of plankton growth must be confirmed and improved using direct measurements from a ship because the equations that convert the satellite reflectance to plankton biomass and growth depend on atmospheric conditions that are changing as well as the specific makeup of the plants that live in a region which is also changing. Here, on the Ronald H. Brown, we filter a lot of water (more than 2600 gallons so far; fig 3) to detect different pigments that each have a unique signature in the wavelengths the satellites measure. From this, we’ll improve the satellite maps to learn how the base of the food web responds to changing climate. We also continuously photograph the plankton community using a FlowCam (fig 4), and measure the size and shape of the cells as well as how they photosynthesize in response to light (using a FIRe instrument; fig 5). Each morning, we also sample the water column to learn how fast the plants and animals are growing by looking at changes in oxygen over time in sealed bottles (fig. 6). This will help us to develop estimates of how much plant based carbon sinks into the deep ocean – affecting the carbon and oxygen breath of the water when it ultimately returns to the surface.

We also tow nets in the upper ocean to learn more about the small animal or zooplankton communities that likely create the fastest source of sinking carbon to the deeper ocean. The water all looks blue, but the plants and animals have been changing radically over the different areas of the Indian Ocean (Figs 4 and 7); from the deserts of the subtropics, to the fertile tropical upwelling areas. These zooplankton samples get photographed and stored at sea for later analysis. Some animals will be examined to learn whether their shells are dissolving in waters with acidic pH. Other samples will be counted (old school) to learn who is there. Some samples will get analyzed with new genetic barcoding techniques (high tech) to find out which DNA occurs in each region. Using old and new school measurements allows us to compare this section with the last one 20 years ago while still staying up to date with modern technologies.

Figure 7: Some of the animals collected across our net tows.

As we steam through these hidden plant and animal habitats we are continually reminded of how little we know about the diverse organisms below the surface that alternately fuel and steal the ocean’s breath (Fig 7).

I07N 101: Intro to Oceanography

Author: Holly Westbrook

Hello! My name is Holly and I am a scientist. When you read the word “scientist” you might imagine a person in a white lab coat, goggles, and gloves, swirling a flask of strange colored liquid, or maybe frowning at a clipboard. Now, sometimes science does look like that, but other times it looks like this:

From left to right, Ian, Andy, and Christian deploying an ARGO float.

The scientists onboard the Ronald H. Brown are “oceanographers,” scientists who study the ocean. It can be a tricky field to study because we have to collect samples from places that can’t be easily reached (for example, the middle of the Indian Ocean).

We collect water samples from the bottom of the ocean all the way up to the top using a piece of equipment called a “rosette.” The rosette has many different things attached to it, to bring up water we use “Niskin bottles” (the gray bottles in the next picture). Once the rosette is on deck and secured we can start sampling. There are many different people who need to get water samples. We have a specific order of who goes when to make sure things stay organized and all the time-sensitive samples are collected quickly. Still, things can get a little crowded.

From left to right, Chuck, Leah, CFCs Chuck, and Ian working in close quarters to get their water samples.

There are a couple of different ways to collect water, many of us use plastic tubes and glass bottles, some use plastic bottles, some use glass syringes, and one person has a bit more of an involved method:

Christian sampling black carbon, looks like a pretty involved process.

A lot of the scientists work 12 hour shifts, we usually have another person who will take over our shift when we are done. That means that no matter the time of day there is always research being done! My shift is from 11:30 pm to 11:30 am. It was a little rough adjusting at first, but by now I’ve gotten used to it. Plus I’ve seen some pretty great sunrises.

A beautiful sunrise I got to see while waiting for my turn at the rosette.

When we’re not working, how we use our time is up to us. We can read outside, watch movies in the lounge, play card games, go to the gym, or talk to friends online—there’s a surprising number of ways to occupy your time!

Breakfast, lunch, and dinner are prepared by the stewards and they are at the same time every day. But there is always something to eat, which is good because I sleep through dinner and wake up several hours before breakfast. There’s things like oatmeal and cereal, but also daily snacks and ice cream at any time.

The days can be repetitive and tend to blend together but the importance of the work and the company we keep makes it all worthwhile!

From left to right: Bonnie, Myself Amanda, Catherine, Carmen, Annelise, and Jenna on a water taxi to Mahé.

International Collaboration at Sea – Being a Japanese scientist on a US vessel

Author: Shinichiro Umeda

The ocean absorbs considerable heat and anthropogenic carbon dioxide (mostly from burning fossil fuels), slowing down the global warming. It is important for the future climate to monitor heat and carbon in the ocean regularly. Although satellite observations and autonomous instruments such as Argo floats are widely used, ship-based hydrography remains the only method for highly accurate measurements of temperature, salinity, and other chemical and biogeochemical parameters over the full water column. The ocean covers about 70% of the Earth surface and international collaboration is inevitable. The international program we are sailing for is called GO-SHIP (Global Ocean Ship-based Hydrographic Investigations Program).

Both JAMSTEC (Japan Agency for Marine-Earth Science and Technology), for which I work, and NOAA are part of GO-SHIP. R/V Ron Brown of NOAA is now observing the I07N section north of 30S. R/V Mirai (Japanese word “future”, see Image 2) of JAMSTEC will occupy the I07S section from 30S to 65S (or ice edge) in the 2019/20 season. The two sections will form a complete trans-basin section, contributing to understanding of the basin scale heat/material circulation of the Indian Ocean.

R/V Mirai has been to the Arctic, Pacific, and Indian Oceans (both subarctic and subtropical) since 1997. Her length is 128.5 m, beam is 19.0 m, depth is 10.5 m, draft is 6.9 m and gross tonnage is 8,706 tons. For hydrographic cruises, she carries 46 scientists on board, deploying CTD, collecting and analyzing water samples, all day and night.

JAMSTEC and NOAA have a long history of collaboration. To better understand and predict climate variations related to El Niño and the Southern Oscillation (ENSO), the TAO/TRITON moored buoy array is operated in the Tropical Pacific Ocean. TAO/TRITON was built over the 10-year period from 1985 to 1994 and is presently supported by JAMSTEC and NOAA.

And another episode of collaboration occurred in 2017. NOAA’s Pacific Marine Environmental Laboratory (PMEL) operates a research mooring at the Kuroshio Extension Observatory (KEO) which is located off the coast of Japan. The KEO surface mooring provides publicly available data including meteorological components such as wind velocity/direction and oceanographic components such as temperature/salinity and surface ocean acidification for international climate researchers worldwide. On October 19, 2017, it broke from its anchor and went adrift. A rescue took place on the high-seas at the end of December 2017, as technicians from JAMSTEC helped recover and redeploy the KEO mooring (See Image 3). The mooring continues to provide important data for the North Pacific research.

There are differences between JAMSTEC and NOAA, such as language, culture onboard, size of scientists onboard, duty team, etc. On the other hand, we (and probably all other sea-going research institutions) all love the sea and science we do, and willing to help each other in need. The collaboration continues.




POM: The living and the dead

Author: Catherine Garcia

POM – What is it? – POM stands for “particulate organic matter”. Sea water particles could be living plankton, dead material, or even plastic bits that have made it out to sea. The dead material sometimes includes old plankton cells, plant matter, fecal pellets, airborne dust particles, river-borne soil particles, etc. The further the Ronald Brown moves away from the coast and into open water, a higher portion of the particles we capture is living phytoplankton, bacteria, and zooplankton.  Jenna and I are looking at the organic portion of the particulate matter, or the living/dead material. When this POM gets dense enough, it sinks out of the sunlit ocean layer and might make it to the ocean bottom if not consumed by bacteria on the way down. We call this the “Biological Carbon Pump”.

Jenna and Catherine filtering POM samples.

POM – Why and how do scientists measure it? – Scientists care about POM because phytoplankton play a VERY large role in removing carbon dioxide (CO2) from the air in the upper ocean. To understand just how much carbon is being removed, scientists need to measure how much carbon is captured in particles and what percentage sinks into the deep ocean by the Biological Carbon Pump. To know how much is carbon, we measure the elemental composition of particulate organic matter to obtain its concentration. The most abundant elements in organic matter are carbon, hydrogen, nitrogen, phosphorus, oxygen, and sulfur.

In the Western Indian Ocean, we are collecting samples for particulate organic carbon, nitrogen, phosphorus, and oxygen. The NOAA/V Ronald Brown has a sea water pump constantly bringing sea water conveniently to our lab bench.  Once we collect ~6L of sea water, all of it is filtered onto glass fiber filters that let any particles smaller than 0.7um flow though.

Glass fiber filter (on left) used to collect POM samples.

It really isn’t any different from than filtering the coffee grinds out of your coffee, except we keep what’s on the filter! Because larger plankton are rarer and a small fraction of the sea water in this area, we filter out any particles larger than 30um to avoid the occasional zooplankton. The filters are frozen after collection and stored frozen until analysis at Dr. Adam Martiny’s lab at the University of California-Irvine.  Once in the lab, the filters for carbon and hydrogen are eventually baked at more than 900oC in an Elemental Analyzer to turn all the carbon and hydrogen into a gas that can be measured. The phosphorus and oxygen are measured using chemical assays against a standard concentration curve.

POM – What does it tell us? – So, I mentioned why we cared about carbon, but why capture the other elements? Until recently the science community accepted a phytoplankton recipe of sorts: 106 parts carbon: 16 parts nitrogen: 1 parts phosphorus and so on. Mix together some carbon from photosynthesis and nutrients from the deep ocean to get your typical model phytoplankton. This ratio gives scientists a good estimate of how much POM is composed of carbon. Globally, an average phytoplankton does almost converge on this ratio of elements first described by Alfred Redfield in 1934. But not always.

Like us, plankton are what they eat. Phytoplankton in particular have extremely flexible elemental ratios. Just how flexible, and what causes them to change their ratios remains an open question. There are several theories that link elemental composition to environmental conditions, which group is present, or even how fast they grow. Jenna and I will try to track down this mystery on the IO7 cruise track.