Effect of River and Wetland Sediments on Toxicity of Metolachlor

Karuppiah, Makesh; Liggans, Girvin; Gupta, Gian

doi:10.1006/eesa.1996.1507

Cited by 11 publications

(6 citation statements)

References 15 publications

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“…Microtox results that are precise have been obtained for xenobiotics in extracts from soils, sludges, and sediments (Bitton and Koopman, 1992;Kong et al, 1995;Karuppiah et al, 1997;Sunahara et al, 1998Sunahara et al, , 1999Cassells et al, 2000;Cook et al, 2000).…”

Section: Discussionmentioning

confidence: 91%

Effect of Dust on the Viability of Vibrio fischeri in the Microtox Test

Park

Hee

2001

Ecotoxicology and Environmental Safety

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Section: Discussionmentioning

confidence: 91%

Effect of Dust on the Viability of Vibrio fischeri in the Microtox Test

Park

Hee

2001

Ecotoxicology and Environmental Safety

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“…Specifically, metolachlor was shown to decrease the number of bacteria in soil when applied at a concentration of 100 mg kg À1 soil (Chang et al, 2001). Furthermore, assays of the impact of metolachlor on the model bacterium Vibrio fischeri revealed EC 50 values of between 5 and 30 mg l À1 water (Gaggi et al, 1995;Karuppiah et al, 1997;Tsui and Chu, 2003;Sakkas et al, 2004). While toxicological effects on bacteria populations were demonstrated in these studies, it should be noted that the concentrations of metolachlor exceeded those normally observed in the aquatic environment, as well as the one used in the current study, by approximately 1000-fold.…”

Section: Discussionmentioning

confidence: 99%

A multiphasic characterization of the impact of the herbicide acetochlor on freshwater bacterial communities

2007

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Acetochlor is the third most frequently detected herbicide in natural waters; however, it is unknown if exposure to environmentally relevant concentrations of acetochlor will impact bacterial community structure and function. This study examined the impact of acetochlor on freshwater heterotrophic bacteria number, and community structure and function using direct counting, community level physiological profiling (CLPP) and denaturing gradient gel electrophoresis (DGGE) analysis. Acetochlor concentration did not appear to correlate with the number of total (P ¼ 0.69) and viable (P ¼ 0.80) bacteria, even at concentrations up to 500 lg l À1 . However, CLPP indicated that acetochlor increased functional diversity as shown by (i) an increase in the number of carbon sources utilized by the microbial community, relative to nonexposed controls and (ii) increased functional evenness within the heterotrophic bacterial community. Conversely, DGGE fingerprints suggested that exposure to acetochlor generally decreased the community complexity, as the average number of DGGE bands in most treatments was significantly less than in the control treatment. Cluster analysis of DGGE fingerprints revealed three distinct, dose-dependent clusters (i) communities exposed to 0, 1 and 5 lg l À1 ; (ii) 50 and 100 lg l À1 and (iii) 500 lg l À1, indicating a relationship between acetochlor concentration bacterial community changes. This study indicated that while exposure to environmentally relevant concentrations of acetochlor resulted in no significant impact to the number of freshwater bacteria, impacts to the function and structure of the community were revealed by adopting a multiphasic approach.

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“…The microtox toxicity test has been used in herbicide degradation, interaction with various aquatic systems, bioavailability, and toxicity studies (Dieter et al, 1994;Gupta and Baummer, 1996;Karuppiah et al, 1997). The objective of this study was to measure the e!ect on toxicity (Microtox EC %) of atrazine and metolachlor in surface waters after exposure to simulated sunlight.…”

Section: Atrazinementioning

confidence: 99%

“…All the water samples were "ltered using 0.45-m "lters (Corning, New York, NY) with vacuum suction prior to light exposure. Emulsi"able concentrates of atrazine (41% a.i) and metolachlor (91% a.i) (Ciba}Geigy, Greensboro, NC) were used to prepare 12 mg/liter concentrations [toxicity of atrazine and metolachlor to various aquatic organisms ranges from 0.005 to 30 mg/liter (Ward and Ballantine, 1985;Uhler, 1991;Karuppiah et al, 1997)] in distilled deionized, river, and bay waters, respectively. Samples were stored at 43C.…”

Section: Sample Preparationmentioning

confidence: 99%

“…A low EC % value indicates high toxicity. Microtox has been used in toxicity testing of various chemicals including pesticides (Somasundaram et al, 1990;Dieter et al, 1994;Karuppiah et al, 1997), methyl tertiary butyl ether (MTBE) (Gupta and Lin, 1995), and biodegradation of herbicide (Gupta and Baummer, 1996). The EC % was calculated using the software (Version 7.08) supplied by Beckman Instruments Inc.…”

Section: Toxicity Analysesmentioning

confidence: 99%

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