Comparing the acute sensitivity of growth and photosynthetic endpoints in three Lemna species exposed to four herbicides.
An ecological impact assessment of four herbicides (atrazine, diuron, paraquat and simazine) was assessed using the aquatic floating vascular plants, Lemna gibba, Lemna minor and Lemna paucicostata as test organisms. The sensitivity of several ecologically relevant parameters (increase in frond area, root length after regrowth, maximum and effective quantum yield of PSII and maximum electron transport rate (ETRmax), were compared after a 72 h exposure to herbicides. The present test methods require relatively small sample volume (3 mL), shorter exposure times (72 h), simple and quick analytical procedures as compared with standard Lemna assays. Sensitivity ranking of endpoints, based on EC50values, differed depending on the herbicide. The most toxic herbicides were diuron and paraquat and the most sensitive endpoints were root length (6.0-12.3 μg L-1) and ETRmax(4.7-10.3 μg L-1) for paraquat and effective quantum yield (6.8-10.4 μg L-1) for diuron. Growth and chlorophyll a fluorescence parameters in all three Lemna species were sensitive enough to detect toxic levels of diuron and paraquat in water samples in excess of allowable concentrations set by international standards. CV values of all EC50s obtained from the Lemna tests were in the range of 2.8-24.33%, indicating a high level of repeatability comparable to the desirable level of <30% for adoption of toxicity test methods as international standards. Our new Lemna methods may provide useful information for the assessment of toxicity risk of residual herbicides in aquatic ecosystems.
Division of Life Science, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea; Lab of Plant Growth Analysis, Ghent University Global Campus, Songomunhwa-ro, 119 Yeonsu-gu, Incheon 21985, Republic of Korea.
Jihae
J
Park
School of Marine Science & Engineering, Plymouth University, Plymouth, Devon, PL4 8AA, United Kingdom.
Murray T
MT
Brown
Lab of Plant Growth Analysis, Ghent University Global Campus, Songomunhwa-ro, 119 Yeonsu-gu, Incheon 21985, Republic of Korea.
Stephen
S
Depuydt
Department of Marine Science, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea.
Jang K
JK
Kim
Water Supply Operations & Maintenance Department, Korea Water Resources Corporation, 200 Sintanjin-ro, Daedeok-gu, Daejun 61949, Republic of Korea.
Dam-Soo
DS
Won
Department of Marine Science, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea. Electronic address: hanalgae@hanmail.net.
Taejun
T
Han
D029064:Araceae / Q000187:drug effects* / Q000254:growth & development*; D001681:Biological Assay; D006540:Herbicides / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects*; D056910:Republic of Korea; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D006540:Herbicides; D014874:Water Pollutants, Chemical
Chlorophyll a fluorescence; Frond area; Herbicides; Lemna; Root length; Toxicity