New bottom sampler prompts re-evaluation of the amount of carbon in ocean sea floor sediments
An improved device for sampling of marine sediments reveals that previous measurements are rather uncertain and may in some cases be directly misleading. This means that many of the measurements that form the basis for calculating the amount of carbon stored in sea floor sediments are of questionable reliability. This carbon storage is an important term in the calculations used to predict the future greenhouse effect.
The new box corer, developed by researchers at Stockholm University and Gothenburg University, can collect samples of soft sediment that are almost completely undisturbed. This should allow the amount of carbon stored in the ocean floor to be more accurately assessed in the future.
- For decades, scientists have relied on equipment that in practice has functioned poorly. We now need to re-evaluate the calculations based on previous measurements says Sven Blomqvist, a researcher at the Department of Ecology, Environment and Plant Sciences, Stockholm University.
Instruments for sampling bottom sediments were first invented over a hundred years ago. Some improvements have since been made, but generally without critically examining how effective they really are. In developing the new device, researchers first carefully recorded – by means of in-situ measurements, video recordings and scuba diving – how traditional instruments really work. This made it apparent that improvements were needed. The new sampling instrument provides sediment cores of much better quality, in terms of the content of carbon, nutrients and bottom-living fauna.
The greenhouse effect is largely driven by the increasing amount of carbon dioxide accumulating in our atmosphere as a result of rampant fossil fuel use. One possible option for reducing this atmospheric carbon dioxide is to enhance its fixation in the ocean and storage in the ocean floors. Dead algae and other organic matter sink slowly to the bottom, and are to some extent sequestered in the sediments. This process slows the increase of the greenhouse effect, and therefore needs to be carefully investigated. Samples of soft sediments collected with reliable methods are a crucial prerequisite for such studies.
The new instrument is described in the article Long overdue improvement of box corer sampling in the journal Marine Ecology Progress Series (538: 13-21).
June 20, 2016
Page editor: Johan Klint
Source: Department of Ecology, Environment and Plant Sciences