a decreasing trendp < 0.001
an increasing trendp < 0.001
In parallel, we found a decreasing trend in DIN loads (− 0.70% annually, p < 0.001) and an increasing trend in TON loads (2.11% annually, p < 0.001) in the five studied Norwegian rivers over the past 27 years (1990–2017) (Table 1 , 2 ) (Fig. 2 c,d).