Register for an account

X

Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.

X

Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

Technology

Science's Underwater Chemical Sampling Bot

A tough, clever device called a hydrocast carousel can autonomously gather seawater samples from a mile down.

hydrocast-carousel.jpg

Newsletter

Sign up for our email newsletter for the latest science news

Oceanographers studying the chemistry of seawater in three dimensions need samples from various depths. A hydrocast carousel is the workhorse that collects these sips from the deep. Attached to a hydrowire cable (1), the carousel dives off the side of a vessel and can reach depths of a mile or more beneath the surface.

Before deploying the sampling gear, researchers program a small computer housed in an aluminum cylinder (2) with the depths at which they want to collect samples. While the carousel is in the water, a Conductivity/Temperature/Depth (CTD) profiler (3) continuously records temperature, salt content, and depth.

When the CTD indicates that the sampler has reached a requested depth, an electromagnet in the latch mechanism (4) releases the caps of a Niskin bottle (5), sealing a water sample inside. In some cases, an attached fluorometer (6) collects data on the water’s chlorophyll content, helping researchers understand the vertical distribution of photosynthetic plankton.

Once the carousel is back on board, researchers analyze the water samples to determine their chemical properties such as the amount of dissolved oxygen gas and the levels of biologically important nutrients, including phosphates, sulfates, and nitrates.

Hydrocasts will provide samples for GEOTRACES, a decadelong international program to measure trace elements like iron and cobalt in the oceans.

2 Free Articles Left

Want it all? Get unlimited access when you subscribe.

Subscribe

Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 70%

Subscribe

Already a subscriber? Register or Log In