Sewage pollution is the main threat to the world’s rivers
According to the social reporter of Moj news agency, a new study conducted by Oxford University shows that pollution Wastewater It is more harmful to rivers than agriculture.
Researchers in the study found that even when wastewater is treated, its discharge into rivers affects water quality much more than agricultural runoff on nearby land.
In this study, experts considered three sources of pollution, including the discharge of treated sewage, agricultural effluents and urban runoff.
For example, the team tested four rivers in England upstream and downstream of sewage discharge points over three different months and found that, in addition to UK water companies having the green light to release treated sewage into rivers, treated sewage in It is also released into the river during rainfall, which not only leads to significant environmental consequences, but can also endanger human health if the water is used for drinking, recreation or agricultural activities.
The findings of this study, which scientists say can be generalized to rivers around the world, show that sewage is a primary pollutant, both treated and untreated, responsible for the increase in nutrients, algae and sewage fungi in rivers.
In addition, wastewater strongly changes the ecosystem by changing the composition of plant, animal and microbial communities in water. Change in river communities Downstream of the sewage inlet, the rivers showed a significant change in invertebrate and algal communities.
The results of this study, published in the prestigious journal Global Change Biology, while stating that the increase of cyanobacteria in river water is very worrying, warns that cyanobacteria can be fatal to many aquatic species, including fish, due to the release of toxic chemicals.
The report adds that although sewage discharge is a dominant threat to rivers, the role of agriculture should not be neglected; Agricultural runoff leads to a decrease in water quality and harms aquatic life.