Effects of atrazine and paraquat on nitrifying bacteria

Gadkari, Dilip

doi:10.1007/bf01055509

Cited by 15 publications

(4 citation statements)

References 13 publications

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“…However, very few studies deal with this issue and it will thus be considered only briefly. Gadkari [114] was able to demonstrate that at concentrations of 1,000 to 2,000 pg/L, ammonium oxidation by nitrogen-fixing bacteria is inhibited. Bretthauer [ 11 51 reported atrazine effects on Paramecium and on a decomposer food chain.…”

Section: Ecotoxicological Effects Of Atrazine On Aquatic Organismsmentioning

confidence: 99%

Ecotoxicological relevance of atrazine in aquatic systems

Huber

1993

Enviro Toxic and Chemistry

171

107

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In this report an attempt is made to outline the ecotoxicological role of atrazine in aquatic ecosystems. A brief discussion of the chemistry and metabolism of atrazine is followed by a discussion of the occurrence of this herbicide in the environment. Peak levels for occurrence of atrazine in surface water range from up to 90 μg/L for flowing water to 2 μg/L for standing water. In reality, most values are significantly lower. As with ground water, in which atrazine has also been detected, great caution must be taken when interpreting data on the presence of atrazine in the environment. Atrazine is taken up by nearly all members of the aquatic biocenoses, but in many cases it is also quickly eliminated. The importance of these processes is discussed. The ecotoxicological effects of atrazine on producers, consumers, and decomposers as well as on ecosystem functions first become observable at levels of 20 μg/L or more; the changes are not lasting, even when studied over long periods. Indirect effects are also taken into account in the definition of the threshold value. Deviations from the ecotoxicological threshold value indicated by higher or lower toxi‐cological threshold values in the case of individual organisms are also evaluated. Furthermore, the threshold value is compared with the environmental concern level (EEC) of atrazine. The final assessment is that although atrazine may be potentially hazardous to the environment, the level of hazard depends on the concentration and degree of exposure. It can be assumed that at concentrations of up to 20 μg/L, atrazine does not cause any permanent damage to aquatic ecosystems.

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Section: Ecotoxicological Effects Of Atrazine On Aquatic Organismsmentioning

confidence: 99%

Ecotoxicological relevance of atrazine in aquatic systems

Huber

1993

Enviro Toxic and Chemistry

171

107

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“…Since the activity of the nitrifying bacteria was highest in the continuous-flow columns, the organisms may be more sensitive to the action of chemical inhibitors (Powell and Prosser, 1986). Sensitivity, however, varies greatly among the genera of nitrifying bacteria (Belser and Schmidt, 1981;Gadkari, 1988).…”

Section: Discussionmentioning

confidence: 99%

A continuous‐flow method for measuring effects of chemicals on soil nitrification

Rhodes

Hendricks

1990

Environ. Toxicol. Water Qual.

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Because the productivity of terrestrial ecosystems is directly related to microbial nutrient cycling, understanding the effects of chemical contaminants on soil microbial processes is important. This study examined the effects of two model chemicals-hundup (glyphosate) and N-Serve (nitrapyrinl-on nitrifying organisms in static, perfusion, and continuous-flow culture systems. Experimental concentrations were approximately 1, 10, and 100 x the spot application rate. Both N-Serve and Roundup were shown to inhibit nitrification in the treated soils. Roundup significantly reduced nitrification at 6.8 and 68 mg g-' dry soil. N-Serve (nitrapyrin) completely inhibited nitrification at levels greater than 42 p g-I dry soil in all cultural methods.In comparative studies with static batch and perfusion culture techniques, the continuous-flow system proved to be both reliable and useful in the culture of nitrifying bacteria. This method provides an alternative to traditional culture techniques in measuring chemical effects on microbial geochemical cycles and provides a new method for use in toxicity testing.

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“…Paraquat, another widely-used herbicide, completely inhibited both ammonium oxidation and nitrite oxidation for 40 days at concentrations as low as 1 mg/L. However, atrazine inhibited only ammonium oxidation at concentrations ranging from 5 to 10 mg/L for 40 days (Gadkari, 1988).…”

Section: Anthropogenic Influences On Nitrogen Cyclingmentioning

confidence: 99%

Ciprofloxacin Effects On Nitrogren Cycling Processes In Freshwater Aquatic Sediments

Nandi¹

2021

Preprint

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Four experiments were designed to assess the effect of ciprofloxacin (cipro) on the function of microbial populations in freshwater environments, specifically on nitrogen cycling. Cipro is a broad-spectrum fluoroquinolone antibiotic used in the treatment of both human and veterinary pathogenic diseases. Previous studies reported the presence of cipro in aquatic environments. This study investigates whether cipro has adverse effects on environmental bacteria which perform critical ecosystem processes associated with the nitrogen cycle. Microcosms containing sediment and synthetic lake water were amended with a series of environmentally relevant concentrations of cipro ranging from 0.5 to 2.5 mg cipro per kg of sediment. Nitrogen cycling processes including nitrification, denitrification and ammonification were measured using a combination of flux measurements (NH4+, NO3-, NO2-), stable isotope techniques ( 15[superscript]N NO₃- dilution) and changes in N₂:Ar and O₂:Ar using Membrane Isotope Mass Spectroscopy (MIMS). Results indicate that cipro has a dose-dependent effect on nitrification, while denitrification is dependent on nitrate availability and may be stimulated by cipro. Ammonification and respiration were not affected at these concentrations. Impacts on nitrification and denitrification are likely to be realized only at the highest concentrations measured in the environment. At the lower end of the environmentally relevant concentration range, observed impacts are not likely to be ecologically important, especially when averaged over an entire lake ecosystem.

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Effects of atrazine and paraquat on nitrifying bacteria

Cited by 15 publications

References 13 publications

Ecotoxicological relevance of atrazine in aquatic systems

Ecotoxicological relevance of atrazine in aquatic systems

A continuous‐flow method for measuring effects of chemicals on soil nitrification

Ciprofloxacin Effects On Nitrogren Cycling Processes In Freshwater Aquatic Sediments

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