Rivers emitting the greenhouse gas
When you will see the new territories which are one of the greenest regions of Hong Kong. The region borders the Chinese mainland and has the majority of Hong Kong’s territory. The beautiful and eye-catching view is away from the crowded buildings that can hide its beauty. The beautiful scene is wrapped around a large area of farmland, rolling greenery, wetlands, mountains, parks, and rivers. But are they as beautiful as they look? The answer is no.
According to a study of 15 of the area’s waterways, the rivers are releasing a large amount of greenhouse gases. According to the research of Derrick Yuk Fo Lai, a professor in the department of geography and resource management at the Chinese University of Hong Kong, “All the river water is highly concentrated with three main greenhouse gases, namely carbon dioxide, methane, and nitrous oxide”. Lai also found that the concentrations of these gases were sometimes 4.5 times higher than the atmospheric concentrations. The study which analyzed the effect of water pollution on the release of greenhouse gas in Hong Kong. The result of the study highlights that this river is a source of continuous emission of greenhouse gases in the environment.
The next important point is the reason behind the contamination of water.
How is the water getting polluted?
The major sources of pollutants were released from livestock farms, misconnections in old buildings, and unsewered premises. In fact, the mean saturation levels of CO2, methane, and nitrous oxide (N2O) in more polluted rivers were approximately 2.2, 1.5, and 4.0 times higher, respectively, than in less polluted rivers.
According to the research Lai “While the magnitude of carbon emissions from our rivers is small relative to that arising from fossil fuel combustion in our daily activities, their contribution to the total greenhouse gas budget of Hong Kong should not be ignored and should be minimized as far as practicable to mitigate future climate change”.
Level of microorganism in the river
Rivers and lakes are estimated to emit up to 3.9 billion tonnes of carbon per year which is around four times the amount of carbon emitted annually by the global aviation industry. When you consider the relatively small area occupied by rivers on the planet, that figure is astounding. Furthermore, aquatic systems such as rivers and lakes are estimated to contribute more than 50% of atmospheric methane, and global river N2O emissions have surpassed 10% of human emissions.
According to Sophie Comer-Warner, a biogeochemist and research fellow at the University of Birmingham, “The reason behind this is that rivers get a huge amount of carbon and nitrogen from the landscapes they drain”. He also says that rivers usually transfer the elements to the ocean but now we can see that their a high level of biogeochemical reactivity in the river. The various forms of carbon and nitrogen the microbes get are broken into other forms through aerobic or anaerobic respiration and because of this process CO2, methane, and N20 is released.
However, the release of small amounts of CO2 and other greenhouse gasses are part of the ecosystem but if the amount is getting higher than it can create problems the environment. Let’s see how harmful it can be for us?
Affecting the surroundings
A study done by the Cuenca urban river system in Ecuador, finds the connection between water quality and greenhouse gas emission. The rate of emission of gas is directly proportional to water quality. This emission of gas also contributes to global warming. According to Long Tuan Ho, a postdoctoral researcher at Ghent University, Belgium, and an author of the study says that the contaminated water can increase the global warming potential (GWP) can increase from two to 10 times. The concentration of CO2 and CH4 in the water increased by ten times and on other hand, the amount of N20 increased by 15 times.
Pollutants such as nitrogen compounds and emissions from human activity are converted to greenhouse gases by microorganisms after joining flowing freshwater bodies. When dissolved oxygen in rivers decreases due to emissions, anaerobic bacteria mineralize organic matter to create CO2 and methane, while denitrifying bacteria convert nitrate (NO3) to nitrous oxide (N2O).
Breaking the chain of contamination
Rivers are polluted by human activities and majorly in urban areas which increase the release of greenhouse gas. It has been found that more than half of the world’s population lives closer than 3km (1.8 miles) to a surface freshwater body, including river networks. As a result, the rivers are getting polluted because 80% of municipal wastewater is still directly discharged into the environment. A major portion of pollutants comes from untreated wastewater, agricultural runoffs, and increased sediment accumulation. The increase in urbanization, agriculture, and aquaculture activity will impact the environment badly. If the amount of CH4 concentration will present on the sites will decrease by ten times then the CO2 and N2O concentrations can decrease by four times. Various programs like the EU Green Deal, EU Water Framework Directive, and Clean Water Act in the United States are running to decrease the emission of this harmful gas.
Ho says that this “ Program is having positive results and are improving the quality of water and also reducing various risk like reducing flood risk, restoring habitat and increasing biodiversity globally,”
Save the environment from the harmful gases
Ho has also given some suggestions for the improvement of water;
- The first is the treatment of wastewater and increasing the numbers of wastewater treatment facilities.
- The next is making buffer corridors around rivers to decrease the flow of pollutants.
- The last is that restoring the natural channel shape and natural flow regime to avoid sediment accumulation, can all help to cut river emissions.
On the other hand, the Lai who studies greenhouse gas emissions from 15 urban rivers, also gave his suggestions that the pollution is also directly linked with the excessive use of fertilizers. The savage network should increase its touch to rural areas. At present, about 6% of Hong Kong’s population remains as a sewerage system but the government is taking steps to connect the population.
The water quality in Hong Kong has improved from last few years as the government is taking appropriate steps but they have a lot of distance to cover to reach their final destination, mainly the rivers in North-western New Territories,” says Lai.”
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