BATS 295 Day 4

Dr Meg Estapa is a post doc at WHOI who is currently working on a project studying how much particulate carbon gets exported into the deep sea. I spoke to her yesterday about her new project and this is what it’s all about…

What is particulate carbon and how is it being measured?
Particulate carbon falls through the water column to the deep sea. It is comprised of dead phytoplankton cells, faecal matter from zooplankton and other substances. As it falls though the twilight zone (0-1000m) a lot of this carbon gets remineralized and only a small amount makes it to the deep sea. Meg is currently trying to measure the particulate carbon flux that gets exported into the deep sea  by using and comparing two different methods. She is also going to compare her sediment trap data with the BATS data.

What is going to be used to measure this particulate carbon in the deep sea?
They are going to be using both neutrally buoyant sediment traps (NBSTs) and profiling floats. NBSTs operate like the BATS traps however instead of the sediment traps being attached to rope the NBSTs are free floating allowing them to drift with the ocean currents reducing hydrodynamic effects. They have four tubes which collect the falling particles. 

one of the NBSTs being deployed

They also deployed two profiling floats which have transmissometers attached to them. Transmissometers shine a beam of light through the water to tell the concentration of suspended particles. Particles that fall onto the upward-facing window of the instrument block the light beam, causing a measurable signal we can relate back to flux. 

Profiling float in the water

The floats can drift in the ocean for months and measure other parameters such as salinity and oxygen. The data from the float is relayed via satellite to Meg's computer. The NBSTs also have transmissometers attached to them so they can compare the sediment trap flux data with the flux data from the transmissometers. This will allow them to see whether transmissometers accurately determine particulate carbon flux. 

One of the four sediment trap tubes contains a gel – what does this gel do?

The gel in the tube is a soft landing for particles that fall in the trap. It preserves the size and shape of the particles so you can identify and chemically analyze the particles.

Close up of a sediment trap tube - the transmissometer is on the left! 

Why is it important to monitor this carbon flux in the ocean?

It is important to monitor the particles that are raining down from the ocean because they are an important part of the carbon cycle. It is difficult to measure carbon flux frequently and if it is possible to measure flux using just profiling floats then this would reduce the need for vessels which are expensive and allow more continuous measurements. There are large parts of the ocean where there is very little data on particulate carbon flux which is why it is important for more continuous monitoring.   

A big thank you to Meg for taking the time to talk to me about her project! Tomorrow we will be recovering the floats, NBSTs and BATS sediment traps – even more photos to come!

Bye Bye NBST number three! See you soon!

BATS 295 Days 2 and 3

This post was actually written last night but unfortunately I couldn't get the internet to work - so you will be getting another post this afternoon as well!  

The past two days have been very busy here at BATS! Friday started with net tows for both the BATS and Princeton University groups. The afternoon was exciting with the deployment of WHOI’s neutrally buoyant sediment traps (NBSTs) which I will talk about in a post tomorrow! We also deployed the BATS sediment trap array which we will be recovering in a couple of days. 

Attaching a host to the CTD to pump water up to the ship from 200m

Day three started nice and early for the BATS team at 3am with the deployment of the production array. After one of the smoothest and quickest deployments I've ever seen we went back to bed to get some sleep before a busy afternoon. This evening we recovered the production array and currently there is a phytoplankton net tow in the water which the Princeton Uni group will be sampling from. 

During the day we sampled the CTD. Here is a little explanation about what a CTD is…  

The CTD going into the water

CTD stands for Conductivity, Temperature and Depth. It is a large oceanographic instrument that we use to sample for water. It has twenty four niskin bottles which can contain 12 litres of water each. Niskin bottles open at both the top and bottom to sample water of a known depth. As the CTD goes through the water column it is attached to the ship with a cable which allows us to close the bottles at depths we want to take water samples from. It has the ability to measure depth, temperature, salinity, fluorescence and oxygen concentration and relays the information back to the ship.  After we take our samples from the CTD we start the filtration process!... (see image below)

Filtering!

To finish this post here are my five best things of the day:
1. Seeing a whale! No photos unfortunately!
2. Freshly baked cinnamon rolls by the amazing chefs Greg and Dexter! (There will be a whole post coming soon dedicated towards food on the ship!)
3. Amazing sunset across the ocean!

4. Seeing squid swim around the ship at night – so cool!

5. A big thank you to Matt for bringing me snacks whilst I wrote this blog post! – You’re in my top five!

Sorry about the short update – I finished work 10 minutes ago and I am a very sleepy BATS tech so I'm off to bed! Tomorrow I am interviewing Dr Meg Estapa about her new exciting sediment trap project! There will be lots of photos!