The study identifies the relative contribution of various bio-optical factors to the total attenuation of ultraviolet radiation (UVR) wavelengths and photosynthetically active radiation (PAR) in temperate coastal waters of Japan by surveying the physical properties of the water column, UVR and PAR penetration, and the absorption characteristics of dissolved and particulate material. Spectral absorbance properties of pigment (aph), detritus (ad) and chromophoric dissolved organic material (aCDOM) displayed both seasonal and wavelength specific variability. On an annual basis, absorbance by aCDOM was the highest absorbing fraction (47–59%) for the UVR wavelengths measured (305, 320, 340 and 380 nm) but decreased (32%) at 450 nm. Contribution of pigments to total absorbance was highest (40–60%) during a spring bloom for both UVR and PAR. A large variability (C.V. > 42%) for annual average attenuation coefficients (Kd[λ]) at respective wavelengths observed suggests that the spectral composition of the water column changes throughout the year in this region. A significant relationship was observed between Kd(λ) and aCDOM at 305, 320, 340 and 380 nm only (P < 0.01) but not for 450 nm (PAR) indicating the role of CDOM in regulating variations in Kd(λ), particularly in the UVR range. The slope S, obtained from a natural-log plot of the absorption coefficient of CDOM against wavelength, ranged between 0.014 and 0.036 nm−1 annually (average = 0.020±0.007, C.V. = 35%) and suggests seasonal changes in the origin of CDOM between terrestrial (low S) and biogenous (high S) CDOM.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 72 • No. 2