The study, which took a “citizen science” approach to data collection, is the first of its kind in Switzerland. More than 150 trained volunteers participated. In total, they examined 95,971 pieces of litter collected on the shores of Swiss rivers and lakes.
Rivers to the Sea
Intensive agriculture near the Mississippi has led to fertilizers leeching into the river, and ultimately the Gulf of Mexico, via soils and waterways. This has resulted in a huge oxygen-deprived dead zone in the Gulf that is now at its largest ever extent, covering an area greater than the state of New Jersey.
“Given their pervasive and persistent nature, microplastics have become a global environmental concern and a potential risk to human populations,” said Rachel Hurley from the University of Manchester and colleagues in their report, published in Nature Geoscience.
The equivalent of one garbage truck full of plastic waste is dumped into the world’s oceans every minute, equal to 8 million tons a year. New research suggests that 90 percent of that waste gets into the oceans through 10 major river systems.
Another reason global warming has not been too bad yet is because the ocean absorbs most of the earth’s excess heat. But oceans are warming due to greenhouse gas emissions. According to the National Oceanic and Atmospheric Administration, half of the increase in ocean heat content since 1865 has occurred over the past two decades. Warmer water holds less oxygen, but the respiration rate of animals (except for marine mammals) increases with temperature, so they need more oxygen at the same time that less is available. A warmer ocean has less turnover (vertical water movements), which normally brings nutrient-rich water up from deep water to the plankton that photosynthesize near the surface. With fewer nutrients, they photosynthesize less and animals can’t get enough food.