Developing methods for partitioning the role of biotic and abiotic phosphorus cycling in streams

  • Funded By: Notre Dame Environmental Change Initiative
  • ECI Investigators: Matt Trentman, Jennifer Tank

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The increased application of phosphorous (P) fertilizers to maintain productivity on agricultural fields has resulted in unintended negative consequences to adjacent aquatic ecosystems. This has contributed to the eutrophication of marine coastlines, which has spread exponentially since the 1960s, with hypoxic or anoxic conditions in shallow waters often caused by anthropogenic actions. In the US, at least 17% of estuarine water bodies are affected by hypoxia due to excess nutrients; these areas, which include northern parts of the Gulf of Mexico, the Chesapeake Bay and the Oregon coast, are some of the largest dead zones in the world. Freshwater systems can also be affected by nutrient pollution. In 2014, a toxic algal bloom in southern Lake Erie resulted in a drinking water ban for nearly half a million people in the Toledo, OH metropolitan area. The continued use of fertilizers and anticipated changes in climate will favor toxic blooms in the great lakes well into the future.

On the landscape, the addition of winter cover crops has been applied to improve soil health, retain soil moisture, and reduce nutrient and soil loss to adjacent waterways during winter and spring when Midwestern fields are normally bare. Additionally, when fertilizer nutrients and sediments are lost to adjacent streams and ditches, floodplain restoration through the implementation of the two-stage ditch may also improve in-stream processing of agricultural inputs.

This research at ND-LEEF builds on the current literature to develop and test methods for partitioning biotic and abiotic processing of phosphorus in headwater streams. Identifying both biotic and abiotic processing of P in streams during base flow conditions will be vital for understanding overall P export as a result of implementation of these combined practices.

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