1:45 PM - 3:15 PM
[O06-P68] The investigation into the origin of the black carbon particles included in Lake Hiruga
Keywords:Black carbon, Varves
Lake Suigetsu, one of the Mikata-Five Lakes in Wakasa, Fukui Prefecture, is famous for its varves. Varves are "lake sediments with a characteristic stripe pattern drawn by mud and other sediments deposited in the lake over a long period of time," and two layers are formed each year. The stripes are formed by alternating deposits of light and dark colored layers as different materials are deposited at different times of the year. The varve of Lake Suigetsu has piled up for about 70,000 years. Here is a picture of the varves at Lake Suigetsu. The varves include layers of volcanic ashes, yellow sand blown by westerly winds from the Asian continent, and plant seeds, providing a valuable source of information on the natural environment of the past.Also, pollen analysis enhances the accuracy of radiocarbon dating. By using pollen analysis you can determine the natural environment at the time the strata were deposited.
The amount of BC particles contained in the mud at the bottom of Lake Hiruga might relate to the industrial and economic development of the region. Black carbon (referred to as BC on our slides) is soot, which is a fine particle of carbon produced by incomplete combustion of organic matter. Studies of pollen analysis of the varve, which have already been made public, can show us about the local environment. Therefore, our research will investigate the development of local industry and economy as well as the local environment by examining the BC of the artificial substances. We want to prove that the economic development of an area can be inferred from the amount of artificial substances contained in the varves.
The hypothesis of our research is that there is a correlation between the economic development of a region and the amount of BC particles in the annual stripes of its age. We can determine their relationship by examining the economic development of the region and the amount of BC particles in the annual stripes of that time. BC is mainly generated by incomplete combustion, such as wildfires, diesel engine emissions, and coal combustion. Since there were no large wildfires in the area around Lake Hiruga, we assume BC is generated mainly by transportation, such as cars, trains, and boats. Therefore, the BC particles seen in our experiment are man-made, and we believe that this result shows that there is a correlation between economic development and man-made BC particles.
Experimental equipment are as follows. Digital microscope, glass slides with drawn border, microscope slide, mud samples from the bottom of the lake, a counting machine, capillary tube.
This was our Method. First, we decided the target samples based on the economic development in Wakasa area from the datable samples. Then, using a microscope, we measured the number of BC particles in the supernatant liquid that was separated during the pollen analysis of Lake Hiruga. A certain amount of Himalayan cedar pollen is added to the supernatant solution.We counted The number of BC particles and the number of Himalayan cedar pollen. And We calculated the amount of BC particles in the annual stripes using a ratio of the amount of cedar pollen. At this stage,the BC and pollen particles should be counted if more than half of the particle is inside the frame on the glass slide.The size of the frame is 2 x 2 mm. Both pollen and BC were tested three times each and averaged. However, there was an outlier in the data at a depth of 540-550 mm from the surface, so we took the average of only two experiments from that depth.Finally, we confirmed there is a relationship between the economic background and the amount of BC particles.
These calculations are based on the 1953 and 1965 flood layers created by the floods as a baseline, and we assume 3 mm of mud is deposited in a year and therefore we calculated the years of the samples.
We only took this into consideration.
One possible reason for the large difference in the number of pollen is that the mixing conditions of the sample black carbon and the solution were different, and that it was not possible to distinguish between those that entered the capillary tubes when they were mixed.
There was a clear difference in the number of BC between the years . We thought that the ratio of black carbon in 1968 was high because of the Fukui National Athletic Meet which was held that year and by athletes rowing on Lake Kugushi that visited near Lake Hiruga using transportation from all over the country. The high ratio of black carbon in 1944 was thought to be due to the fact that houses and forests were burned by the Tsuruga air raids during World War II, resulting in a large amount of black carbon being emitted.
The amount of BC particles contained in the mud at the bottom of Lake Hiruga might relate to the industrial and economic development of the region. Black carbon (referred to as BC on our slides) is soot, which is a fine particle of carbon produced by incomplete combustion of organic matter. Studies of pollen analysis of the varve, which have already been made public, can show us about the local environment. Therefore, our research will investigate the development of local industry and economy as well as the local environment by examining the BC of the artificial substances. We want to prove that the economic development of an area can be inferred from the amount of artificial substances contained in the varves.
The hypothesis of our research is that there is a correlation between the economic development of a region and the amount of BC particles in the annual stripes of its age. We can determine their relationship by examining the economic development of the region and the amount of BC particles in the annual stripes of that time. BC is mainly generated by incomplete combustion, such as wildfires, diesel engine emissions, and coal combustion. Since there were no large wildfires in the area around Lake Hiruga, we assume BC is generated mainly by transportation, such as cars, trains, and boats. Therefore, the BC particles seen in our experiment are man-made, and we believe that this result shows that there is a correlation between economic development and man-made BC particles.
Experimental equipment are as follows. Digital microscope, glass slides with drawn border, microscope slide, mud samples from the bottom of the lake, a counting machine, capillary tube.
This was our Method. First, we decided the target samples based on the economic development in Wakasa area from the datable samples. Then, using a microscope, we measured the number of BC particles in the supernatant liquid that was separated during the pollen analysis of Lake Hiruga. A certain amount of Himalayan cedar pollen is added to the supernatant solution.We counted The number of BC particles and the number of Himalayan cedar pollen. And We calculated the amount of BC particles in the annual stripes using a ratio of the amount of cedar pollen. At this stage,the BC and pollen particles should be counted if more than half of the particle is inside the frame on the glass slide.The size of the frame is 2 x 2 mm. Both pollen and BC were tested three times each and averaged. However, there was an outlier in the data at a depth of 540-550 mm from the surface, so we took the average of only two experiments from that depth.Finally, we confirmed there is a relationship between the economic background and the amount of BC particles.
These calculations are based on the 1953 and 1965 flood layers created by the floods as a baseline, and we assume 3 mm of mud is deposited in a year and therefore we calculated the years of the samples.
We only took this into consideration.
One possible reason for the large difference in the number of pollen is that the mixing conditions of the sample black carbon and the solution were different, and that it was not possible to distinguish between those that entered the capillary tubes when they were mixed.
There was a clear difference in the number of BC between the years . We thought that the ratio of black carbon in 1968 was high because of the Fukui National Athletic Meet which was held that year and by athletes rowing on Lake Kugushi that visited near Lake Hiruga using transportation from all over the country. The high ratio of black carbon in 1944 was thought to be due to the fact that houses and forests were burned by the Tsuruga air raids during World War II, resulting in a large amount of black carbon being emitted.