70,000 tonnes of harmful chemicals leach into aquifers from farms every year, some reach oceans: Study

Harmful chemicals from pesticides not only pollute the soil and water around the farms but also reach rivers and oceans, a new study established. This harms aquatic ecosystems, human health and also pollutes major sources of freshwater. 

Globally, around 70,000 tonnes of potentially harmful chemicals find their way into aquifers every year, the report published in the journal Nature showed. The findings are based on an analysis of the geographical distribution of 92 common pesticides. 

A small part of pesticides applied on fields reach the rivers. Though the amount is small, most of the active agents end up in oceans, threatening marine life and coral reefs. “This puts at risk the very basis of marine and freshwater food chains,” the authors noted. 

Federico Maggi, the study’s lead author from the University of Sydney’s School of Civil Engineering, said:

On paper, 0.1 per cent leaching into fresh waterways might not sound like much. But it only takes a tiny amount of pesticides to have a negative impact on the environment.

Chemical concentrations in about 13,000 kilometres of rivers exceeded safety limits for a number of aquatic plants and invertebrates, the study noted. 

The authors also noted that though about 80 per cent of the pesticides applied degrade in the soil around the crop, the byproducts are just as harmful as the original substance. 

“This degradation of pesticides often occurs as a ‘cascade’ of molecules into the surrounding environment, which can persist in the environment for a long time and can be just as harmful as the parent molecule or applied pesticide,” Maggi noted. 

Glyphosate, for instance, breaks down into a highly persistent and toxic molecule called AMPA, she added. 

Several chemicals such as legacy pesticides and those used in aquaculture, private dwellings and public spaces were left out of the analysis, the scientists said. This means the actual impact of pesticides on ecosystems is much larger, they added. 

The solution is to reduce the use of pesticides and strengthen monitoring, the authors  concluded. Targets for lowering pesticide pollution should be focused on decreasing risk, including reducing amounts and toxicity, because some organisms are at high risk from very toxic pesticides, even when used in low quantities, according to the researchers. 

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