The Environmental Biogeochemistry Laboratory (EBL) focuses research on biogeochemical processes revolving around phosphorus (P) under three axes- P as an essential nutrient for all living beings, P as a contaminant to open waters, and P as a biocidal agent (e.g., herbicide, drugs). EBL research is carried over a trillion-fold scale range, from chemical bond formation/cleavage to micro-macro scale processes in soil and sediment and to landscape and ecosystem processes. The ecosystem-scale research seeks to address questions on the source, sink, transformation, and internal cycling of phosphorus in terrestrial and coastal environments.

Phosphorus: an essential nutrient turned into a pollutant

Phosphorus (P) is a key nutrient for all life forms irrespective of physiological uptake mechanism or metabolic pathway. It is also one of the most scarce nutrients in terms of its demand in both terrestrial and aquatic environments due to typically low concentrations of dissolved inorganic phosphate (micro- to sub-micromolar range). While this is true for most natural environments, many agricultural lands, sewage-contaminated aquifers, and water bodies near densely populated cities often have elevated concentrations of dissolved P. Because of the low stoichiometric need for P compared to other major nutrients (ca. 106C: 16N: 1P; Redfield ratio), small amounts of P addition can cause severe impacts on water quality in receiving catchments or groundwater aquifers and promote hypoxia and eutrophication.

Remineralization pathway in the Chesapeake Bay (cover page of ES&T journal)

Understanding nutrient-soil interactions, however, is not straightforward for P particularly due to i) low concentration of dissolved P compared to soil/sediment P; ii) active but a variable transformation of organic and inorganic P; iii) co-occurring biotic and abiotic reactions to sorb/desorb, dissolve/precipitate, and cycle P at various temporal and spatial scales; and iv) organisms’ variable strategies to uptake and cycle P at different concentrations and compositions of organic and inorganic P compounds. These complexities hamper a better understanding of sources, cycling, and transformation of P in different forms, thus restricting the formulation of effective guidelines for nutrient management plans that could lead to decreased P loss from soils to open waters. For instance, $57 billion was allocated in conservation and preservation programs through the 2014 Farm Bill, but the desired outcomes have not been achieved in major watersheds in the country including Chesapeake Bay, Lake Erie, and Mississippi River.