1. (20 pts). You have been monitoring NO3- concentrations, which is a nutrient used by phytoplankton, seasonally in the surface water of an estuary located in the northern temperate zone. It is a relatively rapidly exchanged estuary with a single river input and an overall water exchange time of ~ 30 +10 days. You plot the distributions as a function of salinity in December and in May and find the patterns plotted below. Using a mixing model to interpret the patterns, December May 30 30 20 20 NO, (HM) 10 10 0 10 20 30 0 10 20 30 Salinity Salinity succinctly give biogeochemically and physically reasonable interpretations for the distribution patterns both within and between data sets. Explicitly note your model assumptions. How might you check your assumptions? CS