Kategorie: News
The which regions are pumping how much wastewater into the ecosystem
"Wastewater often contains pathogens and nitrogen. This poses a risk to both human health and the ecological balance," is how the scientists led by Canadian geographer Cascade Tuholske describe the basic idea behind their new study: they have created a map of the world showing which areas pump how much wastewater into the ecosystem.
China and India are the biggest polluters
According to the study, published in the journal PLOS, China and India are the biggest polluters. About eleven percent of the world's nitrogen from wastewater enters the sea via the Chinese Yangtze River alone. That is more than 680,000 of 6.2 million tons of the substance, which is particularly problematic for the environment.
In total, the scientists examined more than 130,000 waters worldwide for their effluents. Europe did comparatively well. The continent's leaders - Germany and Italy - emit less than a tenth of the nitrogen emissions of China. Switzerland and Austria contribute comparatively even fewer pollutants to their river systems. In particular, the Danube and other rivers such as the Inn and Salzach were studied by the researchers. They found that Austria, for example, only pumps around 13,000 tons of nitrogen waste into the ecosystem each year. A relatively low value.
Population figures and eating habits were the basis for an average value of pollutants that the inhabitants of a country release into the wastewater. They then applied this value to a grid of one-square-kilometer rectangles across the globe and recorded all rivers in them. Previously published studies and data from the UN were also used. Finally, the researchers were able to determine to the kilometer how much wastewater a region produces.
What happens to the wastewater
In contrast to India or many African countries, the leader China has an advantage: slightly more than half of the wastewater from Chinese households is treated by wastewater treatment plants. In Africa, for example Ethiopia or Nigeria, polluted wastewater is almost always discharged into the rivers without any detours and also ends up untreated in the oceans.
Oceans in danger
The discharge of such large quantities of wastewater and nitrogen into the world's oceans poses a major problem. While nitrogen is a substance that marine and riverine life would need in their living environment, too much makes bodies of water uninhabitable (see, for example, news story Marmara Sea). Without sufficient sewage treatment plants and good water treatment, this level continues to increase and ultimately leads to a general extinction of species, a decline in the fish population and thus in fishing, and ultimately to health problems for terrestrial mammals and thus also for us humans.
More information:
Map of wastewater flows
Cascade Tuholske (study author)