Weather of Arabia - When the researchers arrived at the Rocky River, which is considered one of the main tributaries of the great Congo River, they were in a state of astonishment, as the water of this river was so dark that it was difficult to see anything in it, so much so that you could not see your hand in it, and according to what he stated Travis Drake, a researcher at ETH Zurich, who recently published his study in the journal Limnology and Oceanography on the Ruki in collaboration with colleagues from the Sustainable Agroecosystems group led by Johan Six:
“We were impressed by the unique color of this river,” and this sets an example for other universities.
The Rocky River can be considered the largest black-water river on Earth, and this certainly makes it darker than the well-known Rio Negro in the Amazon region. This dark color of the river’s water is related to the abundance of dissolved organic matter it contains, as well as the lack of any sediment as a result of the fragile slope of its course. The river, and these carbon-rich organic materials are mostly deposited into the river by rain as they move from dead plants, and run off decomposing plant material. In addition, in the rainy season, the river floods the forest with water, and this flooding can extend for several weeks, and during this Period, these organic materials are slowly released into the water. As Drake, a researcher at the Federal Institute of Technology in Zurich, points out:
“The Rocky River is basically the tea of the forest.”
These swamps and rainforests are not only distinguished by their dark waters, but there are other aspects that make them unique and distinctive. The Rocky River, which flows one kilometer wide and empties into the Congo River, is considered unique because of its presence in the areas of these swamps and rainforests. Despite its size and importance, It has not been fully studied scientifically, and although the river's seasonal water levels have been documented since the 1930s, no data is available on its chemical composition yet, and no one has yet been able to determine the amount of dissolved organic carbon in the water. This is carbon.
For this reason, Drake and his team set up a record station near Mbandaka in 2019 , a city located near the source of the Rocky River where it meets the Congo River, and measured the water flow every two weeks and the water level daily over the course of an entire year to understand the extent of the impact of this unique river. Drake highlighted the importance of the innovative methods they used in their measurements, and how they often had to deal with technical challenges as a result of the lack of equipment and infrastructure in the Mbandaka region.
The research team collected water samples with each measuring session to learn more about the Rocky River. These samples were sent to the ETH Zurich laboratory, where the researchers analyzed the dissolved organic carbon (DOC) content and estimated the age of the organic matter using the radiocarbon found in the DOC. Their main goal was to verify Whether the soils along the river are releasing carbon into the water (and then into the atmosphere) or being broken down into carbon dioxide.
The researchers had other motives for examining the water, as these samples carry carbon fingerprints from the areas through which the entire river passes. These carbon fingerprints carry important information about the source of carbon and how the surrounding lands are used. Water analysis offers great advantages, as comprehensive information about a large area can be obtained using only one sample, which is similar to a doctor who takes a single blood sample to examine it and determine the patient’s condition. Matty points out , one of the study participants, pointed out this great benefit of water analysis.
Analysis has clearly shown that the Rocky River is one of the richest river systems in dissolved organic carbon (DOC) in the world. The amount of DOC in its waters is four times what is found in the entire Congo River and one and a half times what is found in the Rio Negro River in the Amazon. Although the Roque River drainage basin represents a small portion of the entire Congo Basin, one-fifth of the dissolved organic carbon in the Congo comes from From this little river.
DOC usually comes in the form of organic acids that increase the acidity of river water, releasing carbon dioxide (CO2) as a result of the dissolution of carbonates in the water. Although CO2 emissions through the Rocky River are relatively high across the entire drainage basin, they do not vary Much more so than other tropical rivers, this is due to the slow and calm nature of the Rocky River, making it difficult for carbon dioxide in the water to escape into the air and meaning that if the river is turbulent, you will see higher emissions.
Examination of carbon isotopes also indicates that most carbon comes from forest plants, not soils, with the exception of the short period at the end of the rainy season between March and April where evidence has been found that peat bogs release carbon into the water. How and why this happens in those areas remains a mystery. period in isolation from other periods, and indicates that in general, soils rarely appear in river water, which is a positive thing; Because it also means stabilizing its swamps.
Currently, there is no significant risk of organic matter release from soil bogs; Since they often remain underwater year-round, they are not exposed to oxygen. However, sustainability must be considered in the use of natural resources in the Rocky River Basin region, and land use changes such as deforestation can alter the river regime, dry up swamp soils, and decompose them by bacteria. , which can lead to the release of large amounts of carbon dioxide, and regarding this aspect, Barthel points out the importance of keeping places moist in this region for the benefit of the climate.
Since 2008, Johan Six and his team have been studying the carbon cycle in the Congo Basin, one of the most important tropical river systems on Earth. The Congo Basin is characterized by the transfer of huge amounts of carbon to the sea, and the carbon cycle in this region is affected by vegetation, land use, and during their journey. Originally aimed at studying the biogeochemistry of the Congo Basin and the carbon cycle, the researchers discovered the Rocky River.
After this side trip that led to the discovery of the Rocky River, scientists are now studying other tributaries of the Congo River, such as the Kasai River and the Vimy River, as they work to solve the carbon puzzle gradually and with great precision.
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