BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-10-7207-2013 Photobleaching as a factor controlling spectral characteristics of chromophoric dissolved organic matter in open ocean Yamashita Y. 1 2 Nosaka Y. 2 Suzuki K. https://orcid.org/0000-0001-5354-1044 1 2 Ogawa H. 3 Takahashi K. 4 Saito H. 5 Faculty of Environmental and Earth Science, Hokkaido University, N10, W5, Kita-ku, Sapporo, Hokkaido 060-0810, Japan Graduate School of Environmental Science, Hokkaido University, N10, W5, Kita-ku, Sapporo, Hokkaido 060-0810, Japan Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8564, Japan Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan Tohoku National Fisheries Research Institute, Fisheries Research Agency, 3-27-5 Shinhama-cho, Shiogama 985-0001, Japan 12 11 2013 10 11 7207 7217 Copyright: © 2013 Y. Yamashita et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/10/7207/2013/bg-10-7207-2013.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/10/7207/2013/bg-10-7207-2013.pdf

Chromophoric dissolved organic matter (CDOM) ubiquitously occurs in marine environments and plays a significant role in the marine biogeochemical cycles. Basin scale distributions of CDOM have recently been surveyed in the global ocean and indicate that quantity and quality of oceanic CDOM are mainly controlled by in situ production and photobleaching. However, factors controlling the spectral parameters of CDOM in the UV region, i.e., spectral slope of CDOM determined at 275–295 nm (<i>S</i><sub>275–295</sub>) and the ratio of two spectral slope parameters (<i>S</i><sub>R</sub>); the ratio of <i>S</i><sub>275–295</sub> to <i>S</i><sub>350–400</sub>, have not been well documented. To evaluate the factor controlling the spectral characteristics of CDOM in the UV region in the open ocean, we determined the quantitative and qualitative characteristics of CDOM in the subarctic and subtropical surface waters (5–300 m) of the western North Pacific. Absorption coefficients at 320 nm in the subarctic region were higher than those in the subtropical region throughout surface waters, suggesting that magnitudes of photobleaching were different between the two regions. The values of <i>S</i><sub>275–295</sub> and <i>S</i><sub>R</sub> were also higher in the subtropical region than the subarctic region. The dark microbial incubation showed biodegradation of DOM little affected <i>S</i><sub>275–295</sub>, but slightly decreased <i>S</i><sub>R</sub>. On the other hand, increases in <i>S</i><sub>275–295</sub> and relative stableness of <i>S</i><sub>R</sub> were observed during photo-irradiation incubations respectively. These experimental results indicated that photobleaching of CDOM mainly induced qualitative differences in CDOM at UV region between the subarctic and subtropical surface waters. The results of this study imply that <i>S</i><sub>275–295</sub> can be used as a tracer of photochemical history of CDOM in the open ocean.

 References Biers, E. J., Zepp, R. G., and Moran, M. A.: The role of nitrogen in chromophoric and fluorescent dissolved organic matter formation, Mar. Chem., 103, 46–60, 2007. Blough, N. L. and Del Vecchio, R.: Chromophoric DOM in the coastal environment, in: Biogeochemistry of Marine Dissolved Organic Matter, edited by: Carlson, C. and Hansell, D., Academic Press, 509–546, 2002. Bricaud, A., Ciotti, A. M., and Gentili, B.: Spatial-temporal variations in phytoplankton size and colored detrital matter absorption at global and regional scales, as derived from twelve years of SeaWiFS data (1998–2009), Glob. Biogeochem. Cy., 26, GB1010, <a href="http://dx.doi.org/10.1029/2010GB003952">https://doi.org/10.1029/2010GB003952</a>, 2012. Carder, K. L., Steward, R. G., Harvey, G. R., and Ortner, P. B.: Marine humic and fulvic acids: Their effects on remote sensing of ocean chlorophyll, Limnol. Oceanogr., 34, 68–81, 1989. Del Vecchio, R. and Blough, N. V.: Photobleaching of chromophoric dissolved organic matter in natural waters: kinetics and modeling, Mar. Chem., 78, 231–253, 2002. Endo, H., Yoshimura, T., Kataoka, T., and Suzuki, K.: Effects of CO<sub>2</sub> and iron availability on phytoplankton and eubacterial community compositions in the northwest subarctic Pacific, J. Exp. Mar. Biol. Ecol., 439, 160–175, 2013. Fichot, C. G., Sathyendranath, S., and Miller, W. L.: SeaUV and SeaUVC: Algorithms for the retrieval of UV/Visible diffuse attenuation coefficients from ocean color, Remote Sens. Environ., 112, 1584–1602, 2008. Fichot, C. G. and Benner, R.: A novel method to estimate DOC concentrations from CDOM absorption coefficients in coastal waters, Geophys. Res. Lett., 38, L03610, <a href="http://dx.doi.org/10.1029/2010GL046152">https://doi.org/10.1029/2010GL046152</a>, 2011. Fichot, C. G. and Benner, R.: The spectral slope coefficient of chromophoric dissolved organic matter (S<sub>275-295</sub>) as a tracer of terrigenous dissolved organic carbon in river-influenced ocean margins, Limnol. Oceanogr., 57, 1453–1466, 2012. Fichot, C. G., Kaiser, K., Hooker, S. B., Amon, R. M. W., Babin, M., Bélanger, S., Walker, S. A., and Benner, R.: Pan-Arctic distributions of continental runoff in the Arctic Ocean, Sci. Rep., 3, 1053, https://doi.org/10.1038/srep01053 2013. Granskog, M. A.: Changes in spectral slopes of colored dissolved organic matter absorption with mixing and removal in a terrestrially dominated marine system (Hudson Bay, Canada), Mar. Chem., 134, 10–17, 2012. Green, S. A. and Blough, N. V.: Optical absorption and fluorescence properties of chromophoric dissolved organic matter in natural waters, Limnol. Oceanogr., 39, 1903–1916, 1994. Guéguen, C., Granskog, M. A., McCullough, G., and Barber, D. G.: Characterisation of colored dissolved organic matter in Hudson Bay and Hudson Strait using parallel factor analysis, J. Mar. Syst., 88, 423–433, 2011. Häder, D.-P., Kumar, H. D., Smith, R. C., and Worrest, R. C.: Effects on aquatic ecosystems, J. Photochem. Photobiol. B-Biol., 46, 53–68, 1998. Hasegawa, T., Kasai, H., Ono, T., Tsuda, A., and Ogawa, H.: Dynamics of dissolved and particulate organic matter during the spring bloom in the Oyashio region of the western subarctic Pacific Ocean, Aquat. Microb. Ecol., 60, 127–138, .2010. Helms, J. R., Stubbins, A., Ritchie, J. D., Minor, E. C., Kieber, D. J., and Mopper, K.: Absorption spectral slopes and slope ratios as indicators of molecular weight, source, and photobleaching of chromophoric dissolved organic matter, Limnol. Oceanogr., 53, 955–969, 2008. Helms, J. R., Stubbins, A., Perdue, E. M., Green, N. W., Chen, H., and Mopper, K.: Photochemical bleaching of oceanic dissolved organic matter and its effect on absorption spectral slope and fluorescence, Mar. Chem., 155, 81–91, 2013. Herndl G. J., Muller-Niklas, G., and Frick, J.: Major role of ultraviolet-B in controlling bacterioplankton growth in the surface layer of the ocean, Nature, 361, 717–719, 1993. Kawai, H.: Hydrography of the Kuroshio Extention, in: Kuroshio, edited by: Stommel H., Yoshida K., University of Tokyo Press, 235–352, 1972. Kitidis, V., Stubbins, A. P., Uher, G., Goddard, R. C. U., Law, C. S., and Woodward, E. M. S.: Variability of chromophoric organic matter in surface waters of the Atlantic Ocean, Deep-Sea Res. Pt. II, 53, 1666–1684, 2006. Kobari, T., Mitsui, K., Ota, T., Ichinomiya, M., and Gomi, Y.: Response of heterotrophic bacteria to the spring phytoplankton bloom in the Oyashio region, Deep-Sea Res. Pt. II, 57, 1671–1678, 2010. Kudo, I., Noiri, Y., Cochlan, W. P., Suzuki, K., Aramaki, T., Ono, T., and Nojiri, Y.: Primary productivity, bacterial productivity and nitrogen uptake in response to iron enrichment during the SEEDS II, Deep-Sea Res. Pt. II, 56, 2755–2766, 2009. Matsuoka, A., Huot, Y., Shimada, K., Saitoh, S., and Babin, M.: Bio-optical characteristics of the western Arctic Ocean: implications for ocean color algorithms, Can. J. Remote Sens., 33, 503–518, 2007. Mladenov, N., Sommaruga, R., Morales-Baquero, R., Laurion, I., Camarero, L., Diéguez, M. C., Camacho, A., Delgado, A., Torres, O., Chen, Z., Felip, M., and Reche, I.: Dust inputs and bacteria influence dissolved organic matter in clear alpine lakes, Nat. Commun., 2, 405, https://doi.org/10.1038/ncomms1411, 2011. Mopper, K. and Kieber, D. J.: Photochemistry and the cycling of carbon, sulfer, nitrogen and phosphorus, in: Biogeochemistry of Marine Dissolved Organic Matter, edited by: Carlson, C. and Hansell, D., Academic Press, 455–508, 2002. Nelson, N. B. and Siegel, D. A.: Chromophoric DOM in the open ocean, in: Biogeochemistry of Marine Dissolved Organic Matter, edited by: Carlson, C. and Hansell, D., Academic Press, 547–578, 2002. Nelson, N. B. and Siegel, D. A.: The global distribution and dynamics of chromophoric dissolved organic matter, Annu. Rev. Mar. Sci., 5, 447–476, 2013. Nelson, N. B., Siegel, D. A., and Michaels, A. F.: Seasonal dynamics of colored dissolved material in the Sargasso Sea, Deep-Sea Res. Pt.I, 45, 931–957, 2002. Nelson, N. B., Carlson, C. A., and Steinberg, D. K.: Production of chromophoric dissolved organic matter by Sargasso Sea microbes, Mar. Chem., 89, 273–287, 2004. Nelson, N. B., Siegel, D. A., Carlson, C. A., Swan, C., Smethie, Jr., W. M., and Khatiwala, S.: Hydrography of chromophoric dissolved organic matter in the North Atlantic, Deep-Sea Res. Pt. I, 54, 710–731, 2007. Nelson, N. B., Siegel, D. A., Carlson, C. A., and Swan, C. M.: Tracing global biogeochemical cycles and meridional overturning circulation using chromophoric dissolved organic matter, Geophys. Res. Lett., 37, L03610, https://doi.org/10.1029/2009GL042325, 2010. Omori, Y., Hama, T., Ishii, M., and Saito, S.: Relationship between the seasonal change in fluorescent dissolved organic matter and mixed layer depth in the subtropical western North Pacific, J. Geophys. Res., 115, C06001, <a href="http://dx.doi.org/10.1029/2009JC005526">https://doi.org/10.1029/2009JC005526</a>, 2010. Omori, Y., Hama, T., Ishii, M., and Saito, S.: Vertical change in the composition of marine humic-like fluorescent dissolved organic matter in the subtropical western North Pacific and its relation to photoreactivity, Mar. Chem., 124, 38–47, 2011. Ortega-Retuerta, E., Frazer, T. K., Duarte, C. M., Ruiz-Halpern, S., Tovar-Sánchez, A., Arrieta, J. M., and Reche, I.: Biogeneration of chromophoric dissolved organic matter by bacteria and krill in the Southern Ocean, Limnol, Oceanogr., 54, 1941–1950, 2009. Ortega-Retuerta, E., Reche, I., Pulido-Villena, E., Agustí, S., and Duarte, C. M.: Distribution and photoreactivity of chromophoric dissolved organic matter in the Antarctic Peninsula (Southern Ocean), Mar. Chem., 118, 129–139, 2010. Osburn, C. L., Wigdahl, C. R., Fritz, S. C., and Saros, J. E.: Dissolved organic matter composition and photoreactivity in prairie lakes of the US Great Plains, Limnol. Oceanogr., 56, 2371–2390, 2011. Romera-Castillo, C., Álvarez-Salgado, X., Galí, M., Gasol, J. M., and Marrasé, C.: Combined effect of light exposure and microbial activity on distinct dissolved organic matter pools. A seasonal field study in an oligotrophic coastal system (Blanes Bay,NW Mediterranean), Mar. Chem., 148, 44–51, 2013. Saito, H., Tsuda, A., and Kasai, H.: Nutrient and plankton dynamics in the Oyashio region of the western subarctic Pacific Ocean, Deep-Sea Res. Pt. II, 49, 5463–5486, 2002. Sasaki, H, Siswanto, E., Nishiuchi, K., Tanaka, K., Hasegawa, T., and Ishizaka, J.: Mapping the low salinity Changjiang Diluted Water using satellite-retrieved colored dissolved organic matter (CDOM) in the East China Sea during high river flow season, Geophys. Res. Lett., 35, L04604, <a href="http://dx.doi.org/10.1029/2007GL032637">https://doi.org/10.1029/2007GL032637</a>, 2004. Shank, C. G., Lee, R., Vähätalo, A., Zepp, R. G., and Bartels, E.: Production of chromophoric dissolved organic matter from mangrove leaf litter and floating Sargassum colonies, Mar. Chem., 119, 172–181, 2010. Shank, C. G. and Evans, A.: Distribution and photoreactivity of chromophoric dissolved organic matter in northern Gulf of Mexico shelf waters, Cont. Shelf Res., 31, 1128–1139, 2011. Siegel, D. A., Maritorena, S., Nelson, N. B., Hansell, D. A., and Lorenzi-Kayser, M.: Global distribution and dynamics of colored dissolved and detrital organic materials, J. Geophys. Res., 107, C123228, <a href="http://dx.doi.org/10.1029/2001JC000965">https://doi.org/10.1029/2001JC000965</a>, 2002. Smith, R. C., Prezelin, B. B., Baker, K. S., Bidigare, R. R., Boucher, N. P., Coley, T., Karentz, D., MacIntyre, S., Matlick, H. A., Menzies, D., Ondrusek, M., Wan, Z., and Waters, K. J.: Ozone depletion: ultraviolet radiation and phytoplankton biology in Antarctic waters, Science, 255, 952–959, 1992. Spencer, R. G. M., Butler, K. D., and Aiken, G. R.: Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA, J. Geophys, Res., 117, G03001, https://doi.org/10.1029/2011JG001928, 2012. Stedmon, C. A., Markager, S., and Kaas, H.: Optical Properties and signatures of chromophoric dissolved organic matter (CDOM) in Danish coastal waters, Estuar. Coast. Shelf Sci., 51, 267–278, 2000. Steinberg, D. K., Nelson, N. B., Carlson, C. A., and Prusak, A. C.: Production of chromophoric dissolved organic matter (CDOM) in the open ocean by zooplankton and the colonial cyanobacterium <i>Trichodesmium spp</i>, Mar. Ecol. Prog. Ser., 267, 45–56, 2004. Stubbins, A., Niggemann, J., and Dittmar, T.: Photo-lability of deep ocean dissolved black carbon, Biogeosciences, 9, 1661–1670, <a href="http://dx.doi.org/10.5194/bg-9-1661-2012">https://doi.org/10.5194/bg-9-1661-2012</a>, 2012. Suga, T., Motoki, K., and Aoki, Y.: The North Pacific Climatology of Winter Mixed Layer and Mode Waters, J. Phys. Oceanogr., 34, 3–22, 2004. Swan, C. M., Siegel, D. A., Nelson, N. B., Carlson, C. A., and Nasir, E.: Biogeochemical and hydrographic controls on chromophoric dissolved organic matter distribution in the Pacific Ocean, Deep-Sea Res. Pt. I, 56, 2175–2192, 2009. Swan, C. M., Nelson, N. B., Siegel, D. A., and Kostadinov, T. S.: The effect of surface irradiance on the absorption spectrum of chromophoric dissolved organic matter in the global ocean, Deep-Sea Res. Pt. I, 63, 52–64, 2012. Twardowski, M. S., Boss, E., Sullivan, J. M., and Donaghay, P. L.: Modeling the spectral shape of absorption by chromophoric dissolved organic matter, Mar. Chem., 89, 69–88, 2004. Vernet, M. and Whitehead, K.: Release of ultraviolet-absorbing compounds by the red-tide dinoflagellate Lingulodinium polyedra, Mar. Biol., 127, 35–44, 1996. Welschmeyer, N. A.: Fluorometric analysis of chlorophyll <i>a</i> in the presence of chlorophyll <i>b</i> and phaeopigments, Limnol. Oceanogr., 39, 1985–1992, 1994. Yamashita, Y. and Tanoue, E.: In situ production of chromophoric dissolved organic matter in coastal environments, Geophys. Res. Lett., 31, L14302, <a href="http://dx.doi.org/10.1029/2004GL019734">https://doi.org/10.1029/2004GL019734</a>, 2004. Yamashita, Y. and Tanoue, E.: Production of bio-refractory fluorescent dissolved organic matter in the ocean interior, Nat. Geosci., 1, 579–582, 2008. Yamashita, Y. and Tanoue, E.: Basin scale distribution of chromophoric dissolved organic matter in the Pacific Ocean, Limnol. Oceanogr., 54, 598–609, 2009. Yamashita, Y., Maie, N., Briceño, H., and Jaffé R.: Optical characterization of dissolved organic matter in tropical rivers of the Guayana Shield, Venezuela, J. Geophys. Res., 115, G00F10, <a href="http://dx.doi.org/10.1029/2009JG000987">https://doi.org/10.1029/2009JG000987</a>, 2010a. Yamashita, Y., Scinto, L., Maie, N., and Jaffé, R.: Dissolved organic matter characteristics across a subtropical wetland's landscape: Application of optical properties in the assessment of environmental dynamics, Ecosystems, 13, 1006–1019, 2010b. Ysuda, I.: North Pacific Intermediate Water: Progress in SAGE (SubArctic Gyre Experiment) and Related Projects, J. Oceanogr., 60, 385–395, 2004. Zhang, Y., van Dijk, M. A., Liu, M., Zhu, G., and Qin, B.: The contribution of phytoplankton degradation to chromophoric dissolved organic matter (CDOM) in eutrophic shallow lakes: Field and experimental evidence, Water Res., 43, 4685–4697, 2009a. Zhang,Y., Liu, M., Qin, B., and Feng, S.: Photochemical degradation of chromophoric-dissolved organic matter exposed to simulated UV-B and natural solar radiation, Hydrobiologia, 627, 159–168, 2009b.