Glancing over the periodic table that hangs in the chemistry laboratory, it is hard to see
For Stevens Environmental Engineering professor Dr. David Vaccari, phosphorus keeps him up at night. Simply put, we need phosphorus to grow food. And as the population grows, that demand will only increase.
Historically, the use of phosphorus was cyclical. When humans grew their own food, phosphorus was taken from the soil and returned to the same soil in the form of manure. Now, phosphorus is lost to the environment by transporting food long distances, funneling waste into sewers, and consuming large quantities of animal products. For this reason, phosphorus is in high demand. Yet the finite resource is mined and utilized in an unsustainable way.
Dr. Vaccari first inquired into phosphorus pollution 10 years ago. He has since become aware, in his words, of the “resource sustainability side of the problem.” His team, comprised of himself and researchers Stephen Powers and Xin Liu, has conducted extensive research on the use of phosphorus and recently published the findings in Environmental Science and Technology.
The team developed a model to describe how phosphorus flows through the global food system.
“The model allows us to answer specific ‘what if’ questions to see how certain changes in human behavior could significantly improve the conservation of this resource and, by extension, help sustain the world’s food production,” said Vaccari.
The team’s research focuses on variables that lead to unsustainable phosphorus use: certain animal products in the diet, the management of food and human waste, and the efficiency of manure use. They then manipulate these parameters to predict the outcome of controlling each piece in society. The outcomes correspond to a proposed intervention and its potential efficacy.
The research suggests some surprising results. Dietary changes could reduce the demand for phosphorus substantially but not completely. As people consume less meat, the increased need for plant-based food would again require phosphorus to be mined. Recycling was another piece of the inquiry. Although recycling is a helpful step, reducing waste in consumption is 80% more effective.
Among the hypotheticals addressed in the model, perhaps the most striking is the impact on global diet resulting from a total halt in phosphorus mining. Using only non-mined phosphorus, agriculture could support only one-third of the world’s current population.
If Vaccari had to choose one of his “possible sustainability pathways” to put into action, he would choose to increase manure recycling in animal feeding. This would decrease phosphorus loss and also reduce water pollution. According to Vaccari, unsustainable manure use causes huge algae blooms in local areas and beyond, from Lake Hopatcong to Lake Erie and the coast of Florida.
Dr. Vaccari notes that there is another “master variable” at play: population.
“I think we need to talk more about controlling population growth. This is driving so many of our environmental and sustainability problems,” said Dr. Vaccari.
Phosphorus sustainability is a large-scale issue, but Dr. Vaccari assures that individuals, even Stevens students, can contribute to positive change.
“The best thing that individuals could do is to reduce their consumption of meat, especially beef,” Vaccari said. “That doesn’t mean to stop eating meat entirely, but consider cutting your consumption or switching to more sustainable meat products such as chicken.”
Vaccari and his colleagues hope to expand their phosphorus research to include economic implications and local recommendations so that their ideas are more specific.
“Phosphorus is essential for life,” said Vaccari. “So the plan is to keep it around for a long time by mining phosphate sustainably and responsibly.”
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