Validating Chemical Actinometers as Simple, Cheap Means of Measuring UV Exposure in Aquatic Ecosystems

Mentor 1

John Berges

Location

Union Wisconsin Room

Start Date

28-4-2017 1:30 PM

End Date

28-4-2017 4:00 PM

Description

UV radiation, especially UV-B (320 to 290 nm), has many negative effects in aquatic ecosystems, ranging from the individual (e.g. DNA damage) to the community (e.g. selection for more tolerant taxa). With the thinning of the ozone layer, accurate, regular measurements of UV-B are increasingly important, but, measurements rely on equipment not typically available in aquatic biology labs. An accessible method to measure UV radiation is needed.UV actinometers (chemical devices that react with different wavelengths of light) When exposed to UV radiation nitrate and nitrite participate in reactions that form salicylic acid and p-hydroxybenzoic acid which fluoresce and can be easily measured. UV actinometers have not been widely used, so the goal of this study was to calibrate them using known UV sources, and to apply then in measurements in local freshwaters.
UV actinometers were prepared as solutions of either 1mM NaNO‚ or 10 mM NaNOƒ, (in 2.5 mM sodium bicarbonate with 1 mM benzoic acid), prepared in 11 ml borosilicate vials. To measure UV exposure, the amount of nitrate/nitrite broken down, fluorescence was measured in a plate reader (excitation 305 nm, emission to 410 nm). In order to calibrate, actinometers were exposed to UV from a laboratory transluminator (peak emissions 315 nm) for various period of time and using different amounts of neutral density screening. In addition, exposures to natural outdoor solar radiation were performed.Actinometers were quite sensitive. For example, for nitrate actinometers, relative fluorescence after 8 min exposure to the transluminator was approximately 800 units (vs. 70 units for unexposed actinometers). The exposures showed a linear region of response with amount of UV radiation, with a clear saturation at higher doeses. Currently, we are using data to create a calibration curve and beginning field trials in Estabrook Park pond.

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Apr 28th, 1:30 PM Apr 28th, 4:00 PM

Validating Chemical Actinometers as Simple, Cheap Means of Measuring UV Exposure in Aquatic Ecosystems

Union Wisconsin Room

UV radiation, especially UV-B (320 to 290 nm), has many negative effects in aquatic ecosystems, ranging from the individual (e.g. DNA damage) to the community (e.g. selection for more tolerant taxa). With the thinning of the ozone layer, accurate, regular measurements of UV-B are increasingly important, but, measurements rely on equipment not typically available in aquatic biology labs. An accessible method to measure UV radiation is needed.UV actinometers (chemical devices that react with different wavelengths of light) When exposed to UV radiation nitrate and nitrite participate in reactions that form salicylic acid and p-hydroxybenzoic acid which fluoresce and can be easily measured. UV actinometers have not been widely used, so the goal of this study was to calibrate them using known UV sources, and to apply then in measurements in local freshwaters.
UV actinometers were prepared as solutions of either 1mM NaNO‚ or 10 mM NaNOƒ, (in 2.5 mM sodium bicarbonate with 1 mM benzoic acid), prepared in 11 ml borosilicate vials. To measure UV exposure, the amount of nitrate/nitrite broken down, fluorescence was measured in a plate reader (excitation 305 nm, emission to 410 nm). In order to calibrate, actinometers were exposed to UV from a laboratory transluminator (peak emissions 315 nm) for various period of time and using different amounts of neutral density screening. In addition, exposures to natural outdoor solar radiation were performed.Actinometers were quite sensitive. For example, for nitrate actinometers, relative fluorescence after 8 min exposure to the transluminator was approximately 800 units (vs. 70 units for unexposed actinometers). The exposures showed a linear region of response with amount of UV radiation, with a clear saturation at higher doeses. Currently, we are using data to create a calibration curve and beginning field trials in Estabrook Park pond.