Simulation of bioavailable phosphorus and nitrogen loading in an agricultural river basin in Finland using VEMALA v.3

摘要: Abstract The water quality model VEMALA v.3 reconciles the complexity of a freshwater ecosystem with terrestrial and marine models already implemented in Finland. This unifies VEMALA-ICECREAM, VEMALA-N 1.1 as it uses their independent loading implements simplification biogeochemical RIVE phytoplankton AQUAPHY river network. simulates transport transformations nitrate, ammonium, organic nitrogen, phosphate, particulate inorganic phosphorus, phytoplankton, suspended sediments total carbon during travel to sea. model’s results were satisfactory Aurajoki basin (South-Western Finland) simulating nutrients daily loads, all Nash Sutcliffe coefficients (NSE) ranging from 0.51 0.89 against observations, monthly loads (NSE = 0.4–0.97 estimations). Simulations nitrogen phosphorus comparable estimated annual exception few exceptional years. quantification nutrient cycling processes consistent maximum summer rates for mineralisation 0.1 mgC L −1  d denitrification 55 mgN m −2 resulting loss 4% load entering river. unites previous versions better predict co-impact dissolved phosphate on algal growth therefore eutrophication. Simulation bioavailable rather than will allow distinction various sources, farming actions reduction actions. In simulation, nitrate ammonium represented average 74% 3% respectively Baltic Sea, while constituted 38% Thus, biological impact sea be assessed help managers implement Water Framework Directive