Issue |
J. Eur. Opt. Soc.-Rapid Publ.
Volume 9, 2014
|
|
---|---|---|
Article Number | 14025 | |
Number of page(s) | 10 | |
DOI | https://doi.org/10.2971/jeos.2014.14025 | |
Published online | 21 July 2014 |
Regular papers
The modern Forel-Ule scale: a ‘do-it-yourself’ colour comparator for water monitoring
1
NIOZ Royal Netherlands Institute for Sea Research, NL-1790 AB Den Burg, the Netherlands
2
Institute for Environmental Studies (IVM), VU University Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, the Netherlands
Received:
11
April
2014
Revised:
15
May
2014
The colour comparator Forel-Ule scale has been used to estimate the colour of natural waters since the 19th century, resulting in one of the longest oceanographic data series. This colour index has been proven by previous research to be related to water quality indicators such as chlorophyll and coloured dissolved organic material. The aim of this study was to develop an affordable, ‘Do-it-Yourself’ colour scale that matched the colours of the original Forel-Ule scale, to be used in water quality monitoring programs by citizens. This scale can be manufactured with high-quality lighting filters and a white frame, an improvement with respect to the materials employed to manufacture the original scale from the 19th century, which required the mixing of noxious chemicals. The colours of the new scale were matched to the original colours using instrumental and visual measurements carried out under controlled lighting conditions, following the standard measurement protocols for colour. Moreover, the colours of the scale are expressed in Munsell notations, a standard colour system already successfully used in water quality monitoring. With the creation of this Modern Forel-Ule scale, as a ‘Do-it-yourself’ kit, the authors foresee a possible use of the Forel-Ule number as a water quality index that could be estimated by means of participatory science and used by environmental agencies in monitoring programs.
Key words: Forel-Ule scale / water quality / participatory science / ocean colour / colourimetry / citizen science / water monitoring
© The Author(s) 2014. All rights reserved.
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