Putting the “P” in Plants
Cami weighing plant leaf tissue for a digestion
As climate change becomes more prevalent and sea levels continue to rise, it is important to look at how this affects not only people but our ecosystems as well. The focus of the Tully Agroecology Lab is saltwater intrusion, which is the landward movement of saltwater [1]. The effects of saltwater intrusion can have immediate impacts on drinking water sources, where a small amount of salinity can cause hypertension and stroke, leaving the water undrinkable [1]. Even though longer-term biological effects of saltwater intrusion do not have as much immediate concern as this example, they still present important ramifications for human society because they impact the ecosystems that we rely on [1].
The project that I work on focuses on eutrophication, and specifically how we might be able to reduce the amount of phosphorus entering the Chesapeake Bay. Eutrophication happens when aquatic systems are over-saturated with nutrients, leading to algal blooms and anoxic events that reduce biodiversity and impact water quality [2]. Phosphorus plays an important role in this process due to its low stoichiometric value in comparison to other nutrients (106C: 16N: 1P) [3]. This means that a small amount of phosphorus in water systems can have a large effect on the eutrophication process. Over-fertilized soil and legacy phosphorus can lead to a slow flux of phosphorus (through ditches nearby agriculture fields, phosphorus can leave the soil and enter nearby water systems) which has the potential to be non-reversible unless there are changes in soil management [2].
The Tully Lab is exploring the options of planting salt-tolerant crops (e.g., soybean), efficient nutrient uptake species (e.g., switchgrass), or native marsh species (e.g., saltmarsh hay). I contribute to this project by assisting in the digestion of these plant species so that their chemical properties can be studied to determine the phosphorus uptake each plant has. My role consists of processing the samples by grinding them, making precise mass measurements for each sample, and placing them in the digestion tubes. Once digested, these samples are analyzed using colorimetry to detect the concentration of phosphorus found in the leaf tissue. The hope is that this research leads to a deeper understanding of the relationship between different plant species, phosphorus, and salinity, and how different management practices can be used to help with the adverse effects of saltwater intrusion.
References
Tully, K., K. Gedan, R. Epanch-Niell, A. Strong, E. S. Bernhardt, T. BenDor, M. Mitchell, J. Kominoski, T. E. Jordan, S. C. Neubauer, N. B. Weston. 2019. The Invisible Flood: Chemistry, Ecology, and Social Implications of the Coastal Saltwater Intrusion. BioScience 69: 368-378.
Carpenter, S. 2005. Eutrophication of aquatic ecosystems: bistability and soil phosphorus. PNAS 29: 10002-10005.
Upreti, K., S. R. Joshi, J. McGrath, D.P. Jaisi. 2015. Factors Controlling Phosphorus Mobilization in a Coastal Plain Tributary to the Chesapeake Bay. Soil Science Society of America Journal 79: 826-837.