Using the polyphenylene oxide dosimeter for extended underwater UV measurements

Using the polyphenylene oxide dosimeter for extended underwater UV measurements

The current global warming situation together with recent fluctuating trends in atmospheric ozone levels have resulted in changes occurring to the penetrative ability and distribution of the solar ultraviolet (UV) light field as measured in underwater locales such as in lakes and the ocean. The UV, in particular the UVB, has been shown by numerous studies in the past to have a detrimental effect on many forms of underwater life, ranging from the big to the small, each having their own special niche within the delicate marine ecosystem, which has direct consequences to our own life on the land. So it is extremely important that we measure and document the attributes of the UV underwater so we can enhance our understanding of its widespread effect upon the aquatic world.

The underwater UV light environment has been measured in the past using a multitude of spectroradiometric and radiometric equipment. These instruments have been highly useful for taking underwater measurements of the UV sporadically over a short time frame. However, over long periods of time these spectroradiometers and radiometers become harder to employ, with sizeable amounts of time needed to accurately calibrate and correct them.

This presentation provides measurements extracted from a year long measurement campaign conducted in a simulated sea water environment using a series of Polyphenylene Oxide (PPO) dosimeters immersed at varying depths and aligned to three different inclinations and four azimuths by using a custom built dosimeter submersible float (DSF). The results taken from this campaign were used to calculate an average diffuse attenuation coefficient (Kd) for the sea water in the UVB waveband. This Kd value was compared to another Kd value estimated using data taken using a spectrometer in the same water. Results taken from a long – term calibration completed using a prototype PPO dosimeter in conjunction with a neutral density filter (NDF) will also be presented.

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