Polysulphone film as an underwater dosimeter for solar ultraviolet-B radiation in tropical latitudes

This paper examines the potential of polysulphone film (PSF) as a dosimeter for unweighted solar ultraviolet-B radiation (UVB; 280 to 320 nm) in different seawater conditions in tropical latitudes. PSF's accuracy is determined by water type and depth range. The film may be used over a depth range of 7 m with measurement errors of less than 5 % in oceanic type waters, such as are found around coral atolls and islands. In clear but coloured continental coastal waters the range decreases to 2.2 m. Calibration functions are presented for use of the film both in air (e.g. an intertidal setting) and underwater over the UVB dose range of about 1.5 to 40 kJ m-' A comprehensive analysis of errors arising from the use of PSF, in air and underwater, is given. The film offers a cost-effective and simple technique for studying biological responses to solar UVB radiation in many tropical marine habitats, including intertidal and subtidal coral reefs.