The aims of this project were:

 

An existing marine oceanographic and meteorological buoy (MAMBO) was modified to develop a marine gas monitoring system. It has been equipped with a sea bottom funnel, connected by plastic tubes to the analysis and data logger system for free CO2 and CH4. A second set of instruments has been developed and installed for dissolved CO2 and CH4 measurement. All the collected data are transmitted in real time by phone connection and made available through internet for remote experiment control.

 

 

The monitoring buoy was deployed in the Gulf of Trieste (Northern Adriatic, Italy) and has been operative for months, collecting, transmitting data and demonstrating that even low levels of gasses, due to biological activity in the sediments, may be detected and monitored.

 

For assessment of effects of elevated CO2 concentrations on benthic organisms, a CO2 exposure experiment with RITE’s Benthic chamber rig was performed at 400 m depth in Storfjorden near Ålesund in Norway. Two consecutive10-days exposures were performed with concentrations of 20.000 ppm (parts per million) CO2 in the gas phase in chamber I and 5.000 ppm in chamber II, while chamber III without CO2 addition served as a control. During the experiment, several sensors monitored the water quality inside the chambers, and water samples were withdrawn approx. once per day.

 

 

Microbiological investigations revealed that a moderate increase of CO2 concentrations stimulated methane production and sulfate reduction. Maybe the methanogenic miroorganisms benefitted from dead other bacteria due to less competition for substrates or by consuming the products of their degradation. Similarly, sulfate-reducing bacteria appeared to tolerate changes in CO2 concentrations and/or acidity in their habitat being capable of thriving on degradation products of other organisms which died as a consequence of CO2 addition. In contrast to this highly specialised group of bacteria, the total numbers of bacteria, was highest at the control site and gradually lower after the addition of medium or high CO2 concentrations.

 

 

For more information please contact: Franz May at The Federal Institute for Geosciences and Natural Resources