Why the Reflecting Pool keeps turning green

Chemical & Engineering News sought the expertise of James Jensen, professor in the Department of Civil, Structural and Environmental Engineering, in a report about algae blooms at the Lincoln Memorial Reflecting Pool in Washington, D.C. “Algae need nitrogen, phosphorus, and light to grow,” says Jensen, whose expertise is in water chemistry. “Many waters in North America have enough nitrogen and phosphorus so that algae grow readily in the summer, especially in pretty stagnant waters like the Reflecting Pool.” Without knowing actual concentrations of phosphorus and nitrogen, he says, it’s difficult to assess the role of the water source and what treatments are being applied.