Nutrient Pollution (N & P)

The river Nutrient Pollution indicator is divided into two sub-indicators corresponding to nitrogen (N) and phosphorus (P) nutrient forms representative of water quality impairment: dissolved inorganic N and P (DIN, DIP). Each sub-indicator represents annual-scale mean river nutrient concentration for the entire basin. This assessment is originally derived for Global NEWS 2 basins (Mayorga et al, 2010; Seitzinger et al, 2010) by assuming that the mean annual concentration at the basin mouth (where the mainstem river drains to the coast or to endorheic terminal points) is representative of river channel concentrations across the basin. Concentration values for TFDD river basins are calculated based on spatial intersection with Global NEWS 2 basins, as described under ͆Computation͇. The Global NEWS 2 model run used here is referred to as the Realistic Hydrology Model Run for reference year 2000 (RH2000), and corresponds to near-contemporary conditions using the year 2000 as a reference for all basin model inputs and forcings (Mayorga et al, 2010). RH2000 is based on observed climate forcings and river discharge corrections from river gage observations, and was developed to represent contemporary conditions more realistically than the year-2000 reference model run used in the Millennium Ecosystem Scenarios (MEA) assessment presented in Seitzinger et al. (2010) and related publications. Relative risk category. The category are based on combined concentration of N & P in mg N/L or mg P/L. The details are provided in the description document.