Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 362275
Title Setting critical nutrient values for ditches using the eutrophication model PCDitch
Author(s) Liere, L. van; Janse, J.H.; Arts, G.H.P.
Source Aquatic Ecology 41 (2007)3. - ISSN 1386-2588 - p. 443 - 449.
DOI https://doi.org/10.1007/s10452-005-2835-1
Department(s) Aquatic Ecology and Water Quality Management
Alterra - Centre for Water and Climate
WIMEK
Publication type Refereed Article in a scientific journal
Publication year 2007
Keyword(s) polder ditches - macrophytes - dynamics - lakes
Abstract Critical nutrient loads to prevent duckweed dominance loads in polder ditches were assessed using the eutrophication model PCDitch. In this article the ecological target was set at 50% duckweed coverage. This may be very high for ditches with a nature function, but is not unreasonable for ditches in agricultural areas, with upwelling nutrient rich groundwater, run-off and drainage. Since the change from a ditch with submersed vegetation to duckweed coverage is often a sudden shift, the choice of the amount of duckweed coverage does not influence the calculated loading very much. The main topic of this paper is to present a method to calculate critical loads of nutrients when ecological targets have been set. Sediment type, residence time and water depth influenced the critical loading rates. The calculated critical phosphorus load ranged from 1.8 to 10.2 g P m¿2 year¿1, while the calculated critical nitrogen load stretched from 12.1 to 43.8 g N m¿2 year¿1. The concentration ranges that were derived from the loading rate were 0.19¿0.42 mg P l¿1 and 1.3¿3.3 mg N l¿1. Since PCDitch does not distinguish between Lemna spp. and Azolla spp., no definite conclusions were drawn concerning the effects of nitrogen reduction. In a model situation a pristine ditch was loaded with phosphorus, which resulted into complete duckweed coverage during summer within a few years. When reducing the phosphorus load, it took 10 years before the original situation was reached again. Dredging would accelerate the process of recovery significantly, because the water depth would increase and the phosphorus release from the sediments in summer would decrease.
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