Supplementary material to "Riverine phosphorus gain and loss across the conterminous United States"

Text S1. Estimation of riverine phosphorus loadThe LOADEST, a FORTRAN program designed for estimating constituent loads in streams and rivers through Adjusted Maximum Likelihood Estimation (AMLE), was used to calculate PO4 3-and TP loads at each hydrological station (Runkel et al., 2004).The Akaike Information Criteria (AIC), which evaluates both maximum likelihood and the number of independently adjusted parameters within each model (Akaike, 1974), was utilized for model selection among nine predefined regression models included in LOADEST (Table S1).A total of 935,069 PO4 3-and 1,220,744 TP observations were compiled as inputs for the LOADEST model.The time span and the number of P observations at each station are provided in the shared dataset.