Stuck inside in the lab

Stuck inside in the lab

By Hannah Glover

Lab work is not my favorite. When I was an unhappy, sophomore chemistry major I dreaded every long afternoon spent in the lab. Then I took a geology course where we spent every class outdoors exploring field sites. It was amazing! I immediately switched majors and haven’t looked back (sorry chemistry). Sadly, sometimes I still have to step into a lab. The past few weeks we’ve collected hundreds of samples of sediment and root material. When we’re too exhausted to slog through the mud for another day, we work on processing these samples.

Left: Sediment core collected with a hand-held piston corer. We cut the core into 5-cm-long sections for analysis. Right: We sieve some cores to collect all the root material. The roots hold the sediment together so the cores hold their cylindrical shape. Photo credit: Hannah Glover

One very important measurement we need is the sizes of the grains of sediment in each sample. This tells us all sorts of useful information about the environment because water does a good job of sorting sediment. Mud (the smallest size sediment) can be carried by slow-moving water, while sand can only be moved by faster water. It also tells us what kind of creatures can live in the estuary; oysters and clams can’t live in muddy environments because the mud clogs their lungs. To measure the grain size, we take a little bit of sediment, add hydrogen peroxide to remove all the organic stuff, and then run each sample though…a grain size analyzer! It’s not the most thrilling activity, but the data is rewarding.

Samples lined up on the bench ready for analysis. It’s easy to get samples mixed up, so working methodically is important. Photo credit: Hannah Glover

We also measure all the root material in the cores we’ve collected. Mangroves roots stabilize the sediment in the estuary, allowing more mud to accumulate. But, the roots are slowly decaying where the mangroves have been cut down. We carefully filter each sample and remove all the root material so that we can dry it and weigh it. This will tell us how fast the root material is decaying and where the sediment is least stable.

Finally, we’re preparing some samples for shipping so that I can analyze the age of the sediment back at the University of Washington. We measure age using the radioactive decay of the naturally occurring lead-210 isotope.  We can only do this in labs that are set up for radioactive procedures. Luckily, my home institution has everything we need! So, I will be flying home with lots and lots of mud.

Lab work may not be my favorite activity, but it’s fun when you have good company. And the promise of more sunny days of field work in the future!

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