Fatemeh Hashemi and co-authors from the Biowater project were very early keen to investigate the dynamics of nitrogen (N) and phosphorus (P) forms across the range of Nordic mini-catchments. They wanted to develop “catchment cartoons” that could be used by scientists when communicating results to stakeholders and decision makers. Fatemeh’s newly published paper in the Journal of Water with the title ‘Conceptual Mini-Catchment Typologies for Testing Dominant Controls of Nutrient Dynamics in Three Nordic Countries’ is a first step in developing such catchment cartoons.

Grab sample data on nutrient concentrations and mean daily discharge from 87 Nordic streams draining mini-catchments were collected among the partners in Finland, Sweden and Denmark for a recent 8 years period (2010-2017). Data was analyzed statistically in ‘R’ for their stream export behaviour (dilution, constant, enrichment) and hysteresis rotational pattern (clock-wise, no rotation, anti-clockwise). The mini-catchments were classified into 9 response types shown in the diagram.

The dominant nutrient export regimes were enrichment for Nitrate (NO3⁻) and constant for Total N, Dissolved Reactive P (DRP), and Particulate P (PP). Nutrient hysteresis patterns were primarily clockwise or no hysteresis. Similarities in types of C-Q relationships were investigated using Principal Component Analysis (PCA) considering effects of catchment size, land use, climate, and dominant soil type. The PCA analysis revealed that land use and air temperature were the dominant factors controlling nutrient C-Q types in the Nordic countries. Water | Free Full-Text | Conceptual Mini-Catchment Typologies for Testing Dominant Controls of Nutrient Dynamics in Three Nordic Countries Therefore, the nutrient export behaviour in streams draining Nordic mini-catchments seems to be dominantly controlled by their land use characteristics and, to a lesser extent, their climate.

Hashemi, F.; Pohle, I.; Pullens, J.W.; Tornbjerg, H.; Kyllmar, K.; Marttila, H.; Lepistö, A.; Kløve, B.; Futter, M.; Kronvang, B. Conceptual Mini-Catchment Typologies for Testing Dominant Controls of Nutrient Dynamics in Three Nordic Countries. Water 2020, 12, 1776. doi:10.3390/w12061776

Feature image: Eva Skarbøvik.