Summer has finally arrived in Nova Scotia, and we couldn’t have been more eager to get out from behind our desks again! This time we decided to take out the eosGP; so we bought a boat, the ‘SS Eosense’ – a very luxurious 2 person rubber dinghy.
Our slow take off.
Eosense is located in Burnside – an industrial park in Dartmouth, Nova Scotia. Nova Scotia is well known for its beautiful coastlines and abundance of fresh- and saltwater wetlands. Some call Dartmouth the City of Lakes, and we are lucky enough to have one in our own backyard: Spectacle Lake! It may not be the best lake to dive into on a hot summer day, but its unique wetland ecosystem made it the perfect place to take the eosGP out for a spin.
Figure 2: Eosense and Spectacle Lake location.
Spectacle Lake is smack dab in the middle of a large industrial park, which houses about 2,000 businesses and 30,000 employees. The lake is sheltered by the surrounding buildings making it quite stagnant with little or no wind. What makes the lake unique is that each side of the lake has a different ecosystem. The city of Halifax actually only considers the right side an actual lake and the left side is categorized as a bog/swamp, as shown below in Figure 3.
Figure 3: Nova Scotia Lake Inventory
On one side you have deep and cold water. The other side is shallow (1/4 meter deep), and a lot warmer. We anticipated there would be a difference in concentration based on the very different appearance, so we took out the eosGP to compare the carbon dioxide (CO2) concentration on each side.
Figure 4: Pictures of both sides of the lake.
The eosGP is the adventurer of our greenhouse gas monitoring instruments. It provides continuous and accurate in-situ monitoring in aquatic or terrestrial ecosystems. It’s compact size allows for easy and quick deployment! We simply attached it to a battery and a volt meter and we were on our way. We let the eosGP float along beside us as we took measurements around the lake to keep equilibration time down.
Figure 5: the eosGP
Measurement #1
We started on the shallow side of the lake; it was full of lily pads and other vegetation. The water was quite shallow – no more than half a meter at most. We left the eosGP at each plot for 20 mins. The temperature of the water on this side was 21.72 °C.
Note: The eosGP was used only to get a relative temperature measurement.
Measurement #2
Our next measurement was taken on the same side of the lake farther off shore. The water depth was about 2 feet and the vegetation was the same as the first plot. The temperature was 21.16 °C.
Concentration measurement: 892 ppm
Measurement #3
This measurement was taken in the middle of the lake, about 1 meter depth. The temperature was 18.92 °C.
Concentration measurement: 808 ppm
Measurement #4
The next measurement was taken on the other side of the lake. The temperature on this side dropped to 18.92 °C. The water was a lot deeper, we couldn’t see the bottom. There were very few lily pads.
Concentration measurement: 520 ppm
Measurement #5
Our final measurement was taken at the edge of the left side of the lake. The temperature remained close to the last one; it was 19.20 degrees. There was a little more vegetation at this point then the last 2.
Concentration measurement: 508 ppm
Summary of plots
Given the difference in appearance of both sides of the lake it was not surprising that the CO2 concentrations would also fluctuate. The left side had significantly higher CO2 concentration than the right. The left side, or the swamp side, had very shallow warm water, had a floor covered in moss and a layer of lily pads covering the surface. The swamp side also had a lot of fish and amphibians swimming around and a lot of biological activity. Once we moved to the right side of the lake which was deeper and colder there was a drastic drop in CO2 concentration. The right side of the lake had significantly less vegetation and biological activity. It was very interesting to see one body of water with two different stories. We were very lucky to find this lake in our backyard as it is a perfect example on how diverse ecology actually is!