Around the world, eutrophication of rivers, lakes, streams and oceans is increasingly becoming a prominent environmental concern. Fertilizer nutrients and other chemical compounds are contaminating these water sources after washing away from residential lawns, public gardens and agricultural lands. Once in the watershed, phosphorus, nitrogen and similar nutrients promote abnormally robust growth of algae. When the algae eventually rot, the decomposition process depletes the oxygen supply in the water, causing fish and other organisms to die off, according to the U.S. Geological Survey.
As eutrophication gets worse around the world, environmental scientists and farmers are working to improve agricultural practices to reduce nutrient pollution in runoff. One team of scientists from Stanford University decided to focus their research on oil palm plantations in Indonesia. They concluded that this cash crop not only contributes to global warming, but also to the contamination of freshwater, as published in the Journal of Geophysical Research: Biogeosciences.
Where does palm oil appear?
According to the study authors, the palm oil industry is worth billions of dollars. In addition to being used as a cooking oil, this commodity is used in the production of peanut butter, bread, shampoo, shaving cream and other staple items found in the typical grocery store.
One reason why palm oil is drawing so much attention from environmental scientists is that plantations are taking up more land, particularly in Indonesia. The nation is home to the world's third largest rainforest, and it's the producer of half the global supply of palm oil. According to PricewaterhouseCooper Indonesia, the production of crude palm oil in Indonesia increased 182 percent between 2000 and 2010. As for the land itself, PwC projected that the amount of area devoted to oil palm plants would increase from nearly 8 million hectare in 2010 to about 13 million hectare in 2020.
This could be detrimental to the environment for several reasons. Turning diverse rainforest habitats into monocultures mainly devoted to one form of plant life upsets the native ecological balance and reduces the local flora's ability to absorb carbon dioxide and other greenhouse gases from the atmosphere. Additionally, pesticides wash away in the runoff, and contaminate the watershed. Fertilizers contribute to nutrient pollution and eutrophication.
Monoculture is as bad as clearcutting
Previously, the Stanford researchers studied the impact of oil palm monoculture on greenhouse gases. To find out how this crop affects the environment, they compared water samples from streams the flowed through plantations to samples from the federally protected Gunung Palung National Park. They discovered that water near the plantations was 4 degrees Celcius warmer than that which flowed through the rainforest. Additionally, the former source had sediment concentrations that were 550 times greater, and levels of oxygen depletion that were bigger during a drought.
"Local communities are deeply concerned about their freshwater sources," study co-author Lisa Curran, a professor of ecological anthropology at Stanford, said in a statement. "Yet the long-term impact of oil palm plantations on freshwater streams has been completely overlooked until now. We hope this work will highlight these issues and bring a voice to rural communities' concerns that directly affect their livelihoods."
"Our findings suggest that converting logged forests and diverse smallholder agricultural lands to oil palm plantations may be almost as harmful to stream ecosystems as clearing intact forests," co-author Kimberly Carlson said in a statement.
To help improve agricultural practices related to the cultivation of oil palms, the Roundtable on Sustainable Palm Oil and other organizations suggested that natural vegetation be allowed to grow in areas near streams. Additionally, dense road networks should not intersect near waterways. However, Curran and Carlson noted that more protection may be needed.
