Document Detail

Mixture toxicity of three photosystem II inhibitors (atrazine, isoproturon, and diuron) toward photosynthesis of freshwater phytoplankton studied in outdoor mesocosms.
MedLine Citation:
PMID:  18800510     Owner:  NLM     Status:  MEDLINE    
Mixture toxicity of three herbicides with the same mode of action was studied in a long-term outdoor mesocosm study. Photosynthetic activity of phytoplankton as the direct target site of the herbicides was chosen as physiological response parameter. The three photosystem II (PSII) inhibitors atrazine, isoproturon, and diuron were applied as 30% hazardous concentrations (HC30), which we derived from species sensitivity distributions calculated on the basis of EC50 growth inhibition data. The respective herbicide mixture comprised 1/3 of the HC30 of each herbicide. Short-term laboratory experiments revealed that the HC30 values corresponded to EC40 values when regarding photosynthetic activity as the response parameter. In the outdoor mesocosm experiment, effects of atrazine, isoproturon, diuron and their mixture on the photosynthetic activity of phytoplankton were investigated during a five-week period with constant exposure and a subsequent five-month postexposure period when the herbicides dissipated. The results demonstrated that mixture effects determined at the beginning of constant exposure can be described by concentration addition since the mixture elicited a phytotoxic effect comparable to the single herbicides. Declining effects on photosynthetic activity during the experiment might be explained by both a decrease in water herbicide concentrations and by the induction of community tolerance.
Stefanie Knauert; Beate Escher; Heinz Singer; Juliane Hollender; Katja Knauer
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental science & technology     Volume:  42     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2008 Sep 
Date Detail:
Created Date:  2008-09-19     Completed Date:  2008-10-24     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  6424-30     Citation Subset:  IM    
Department of Environmental Sciences, University of Basel, 4056 Basel, Switzerland.
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MeSH Terms
Atrazine / toxicity*
Diuron / toxicity*
Herbicides / toxicity*
Phenylurea Compounds / toxicity*
Photosynthesis / drug effects*
Photosystem II Protein Complex / antagonists & inhibitors*
Phytoplankton / drug effects*,  physiology
Reg. No./Substance:
0/Herbicides; 0/Phenylurea Compounds; 0/Photosystem II Protein Complex; 1912-24-9/Atrazine; 330-54-1/Diuron; 34123-59-6/isoproturon

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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