A chlorophyll meter is a device for measuring the chlorophyll content in water or in plant organisms. In oceanography, the device name is usually called an A-c meter. The technology utilized in devices for plant studies compared to aquatic water testing use quite different technologies.
|This article is written at a definitional level only. Authors wishing to improve this entry are inivited to expand the present treatment, which additions will be peer reviewed prior to publication of any expansion.|
In oceanography, an A-c meter is an instrument used to perform in-situ measurements of the amount of chlorophyll in water. It does this by pulling water into two tubes, one measuring light absorption and the other attenuation. A beam of light with a wavelength rotating among three values is projected into each tube. The attenuation tube determines light absorption and scattering by measuring how much of the original light beam remains after it passes through the water inside the blackened tube. The absorption tube determines only how much light is absorbed by particles by measuring how much light is left of the original beam including that which has bounded off particles. This tube is lined with a quartz mirror which, in contrast to the absorbing black surface in the attenuation tube, reflects scattered light toward the detector. Chlorophyll causes a large change in the attenuation of light with a wavelength of about 676 nanometers, so a measurement of attenuation at the appropriate wavelength is a proxy measurement of chlorophyll concentration to first order. A fluorometer can also be used to measure chlorophyll.
- A.K. van den Berg and T.D. Perkins. 2004. Evaluation of a portable chlorophyll meter to estimate chlorophyll and nitrogen contents in sugar maple (Acer saccharum Marsh.) leaves. Forest Ecology and Management 200; 113–117.