Quantifying seasonal export and retention of nutrients in West European lowland rivers at catchment scale

Abstract

Abstract:To set accurate critical values for the protection of lakes and coastal areas, it is crucial to know the seasonal variation of nutrient exports from rivers. This article presents an improved method for estimating export and in-stream nutrient retention and its seasonal variation. For 13 lowland river catchments in Western Europe, inputs to surface water and exports were calculated on a monthly basis. The catchments varied in size (21 to 486 km 2 ), while annual in-stream retention ranged from 23 to 84% for N and 39 to 72% for P. A novel calculation method is presented that quantifies monthly exports from lowland rivers based on an annual load to the river system. Inputs in the calculation are annual emission to the surface waters, average monthly river discharge, average monthly water temperature and fraction of surface water area in the catchment. The method accounts for both seasonal variation of emission to the surface water and seasonal in-stream retention. The agreement between calculated values and calibration data was high (N: r 2 D 0Ð93; p < 0Ð001 and P: r 2 D 0Ð81; p < 0Ð001). Validation of the model also showed good results with model efficiencies for the separate catchments ranging from 31 to 95% (average 76%). This indicates that exports of nitrogen and phosphorus on a monthly basis can be calculated with few input data for a range of West European lowland rivers. Further analysis showed that retention in summer is higher than that in winter, resulting in lower summer nutrient concentrations than that calculated with an average annual input. This implies that accurate evaluation of critical thresholds for eutrophication effects must account for seasonal variation in hydrology and nutrient loading. Our quantification method thus may improve the modelling of eutrophication effects in standing waters.

Changing weather conditions and floating plants in temperate drainage ditches

“…The present model performed best when nutrient limitation was incorporated. Nutrient concentrations are constant in the model, although in the field they follow a seasonal pattern with usually higher concentrations of total nitrogen and, to a lesser extent, total phosphorus in winter and lower concentrations of these nutrients in summer (De Klein & Koelmans ). For ditches covered with a dense duckweed layer, this nutrient pattern might be different as additional phosphorus may be released from the sediment under anoxic conditions because binding by iron will no longer occur (Geurts et al .…”

Identification Of River Retention Coefficients for Nutrients In Melen Watershed

“…where T is the temperature. In their study, de Klein and Koelmans (2011) noticed that the correlation between measured and calculated values for the training set was high (N: r 2 = 0.93; p < 0.001 and P: r 2 = 0.81; p < 0.001).…”

“…Hence, the retention model of de Klein and Koelmans (2011) is based on 112 rivers; TN and TP retention models of de Klein and Koelmans (2011) is considered as the most reliable models for our research area. The retention and loss of nutrients in river systems specified using the approach of de Klein and Koelmans (2011). Monthly retention of nitrogen can be estimated from surface water area specific runoff as seen in Equation 1.…”

Role of hydrological factors in shaping water chemistry of small flow-through Polish lake

“…For the first time in Polish floodplain lakes, allometry has been used to determine an influence of fluvial impulse on the morphometry of floodplain lakes (Ferencz and Dawidek 2015). Biogens are the most important ions in shaping lakes ecological state (the cause of progressive eutrophication) (Sheffer 1998;Klein and Koelmans 2011). However, hydrological dynamic of a catchment is a driving force of in-lake processes, e.g., flushing time, the degree and rate of ionic transformation (Müller et al 1998;Lee et al 2009;Liu et al 2011).…”