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Dataset - Low buffering capacity and slow recovery from anthropogenic phosphorus pollution in watersheds

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Excess anthropogenic phosphorus (P) in watersheds, transported with runoff, can result in aquatic eutrophication, a serious global water quality concern. Watersheds can retain P, especially in their soils, which can serve as a buffer against the effect of excessive use of P. However, whether there is a quantifiable threshold at which a watershed exceeds its optimal P buffering capacity (beyond which riverine loads would dramatically increase) remains unknown. Here we quantified a watershed P buffering capacity threshold based on P accumulation data over 110 years in 23 watersheds of a large North American river basin with globally representative agricultural soils. We found a surprisingly low threshold of just 2.1 t P km-2 (0.03 - 8.7 t P km-2). Beyond this, further P inputs to watersheds cause a significant acceleration of P loss in runoff. Using a simple exponential decay model, the time estimated to eliminate legacy P via run-off in our watersheds ranges from ~100 to over 2000 years. The rapidity with which the watershed buffering threshold can be surpassed during accumulation, particularly given current anthropogenic P input rates, versus the long return to baseline suggests that new strategies to reconcile watershed activities and water quality are urgently needed.

Units of variables in the dataset:

year: Years for which NAPI and riverine TP export have been calculated.

Rivername: Name of the rivers draining each of the 23 watersheds of this study

DrainageArea: Drainage area of the different watersheds

spNAPI: Net Anthropogenic P inputs to watersheds (kg P km-2 yr-1)

spTP: Riverine TP loads at the outlet of each watershed in years where water quality data was available (1985-2011; kg P km-2 yr-1). Cells with zeros indicate years were no water quality data was available. Phosphorus loads in these years were estimated following the methods described in the article.


Fonds de Recherche Nature et Technologie du Québec (FQRNT), National Science and Engineering Research Council of Canada (NSERC)