Researchers from Duke University reveal that use of nanomaterial in agrochemicals could lead to toxic algae outbreaks in streams and wetlands.
Use of nanomaterial in agrochemicals like pesticides and fungicides increased considerably in recent years to provide effective disease protection and better yield, while reducing the amount of toxins sprayed on agricultural fields. However, these nanomaterial when mixed with nutrient runoff from fertilized farms lead to toxic algae outbreaks in nearby streams and wetlands.
According to Marie Simonin, the lead author of the study and associate professor of Biology at Drake University, the nano-scale size of the materials renders more surface area for interactions and reactions in pesticides. These interactions magnify toxic algae blooms in water streams. Nanomaterial are mostly composed of carbon nanotubes and teeny tiny particles of silver, titanium dioxide and other metals. These nanomaterial are used in commercial products, lighter electronics, self-cleaning fabrics, and smart food packaging. Agricultural pesticides consisting these materials possess more target delivery based approach on crops. Such wide range of applications generated tremendous interest and investment in nanomaterial. However, its potential threats on human health and environment are hardly understood.
The researchers set up tanks with sandy sloped bottoms filed with water, soil and a variety of wetland plants and animals to mimic small wetlands. For a period of nine months, the tanks got a weekly dose of algae-promoting nitrates and phosphates found in nanoparticles of fertilizers. The water chemistry and plant and algae metabolism and nanoparticle accumulation was monitored in the tanks. The results were published in journal Ecological Applications on June 25, 2018.
According to STATNANO, around 80,400 metric tons of nanomaterial residue is released into soils and 29,200 metric tons is mixed in natural water bodies every year. The nutrients run fall of nitrogen and phosphorous leads to uncontrolled growth of toxic algae. This creates a thick covering of green algae on the water surface, blocking sunlight to reach the bottom, posing fatal threats to aquatic life. Reduced oxygen levels in water gives rise to dead zones where fish and other organisms cannot service.