State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
Photochem Photobiol. 2010 May-Jun;86(3):586-92. doi: 10.1111/j.1751-1097.2009.00694.x. Epub 2010 Feb 11.
We carried out experiments to evaluate seasonal changes in the impacts of UV radiation (UVR, 280-400 nm) on photosynthetic carbon fixation of phytoplankton assemblages. Surface water samples were obtained in the coastal area of the South China Sea, where chlorophyll a ranged 0.72-3.82 microg L(-1). Assimilation numbers (photosynthetic carbon fixation rate per chl a) were significantly higher during summer 2005 than those in spring and winter 2004. The mean values obtained under photosynthetically active radiation (PAR) were 2.83 (spring 2004), 4.35 (winter 2004) and 7.29 microg C (microg chl a)(-1) h(-1) (summer 2005), respectively. The assimilation numbers under PAR + UVR were 1.58, 2.71 and 5.28 microg C (microg chl a)(-1) h(-1), for spring, winter and summer, respectively. UVR induced less inhibition of photosynthesis during summer 2005 than during the other seasons, in spite of the higher UVR during summer. The seasonal differences in the productivity and photosynthetic response to UV were mainly due to changes in water temperature, while irradiance and vertical mixing explained >80% of the observed variability. Our data suggest that previous studies in the SCS using UV-opaque vessels might have overestimated the phytoplankton production by about 80% in spring, 61% in winter and 38% in summer.
我们进行了实验，以评估紫外线（UVR，280-400nm）对浮游植物组合光合作用碳固定的影响随季节的变化。在南海沿海地区采集了表层水样，叶绿素 a 浓度范围为 0.72-3.82μg L(-1)。2005 年夏季的同化数（每 chl a 的光合作用碳固定率）明显高于 2004 年春季和冬季。在光合有效辐射（PAR）下获得的平均值分别为 2.83（2004 年春季）、4.35（2004 年冬季）和 7.29μg C（μg chl a）(-1) h(-1)（2005 年夏季）。PAR+UVR 下的同化数分别为 1.58、2.71 和 5.28μg C（μg chl a）(-1) h(-1)，分别为春季、冬季和夏季。尽管夏季 UVR 较高，但 2005 年夏季 UVR 对光合作用的抑制作用小于其他季节。生产力和对 UV 的光合作用响应的季节性差异主要归因于水温的变化，而辐照度和垂直混合解释了观察到的变异性的>80%。我们的数据表明，之前在南海使用不透明紫外线容器进行的研究可能高估了浮游植物的春季产量约 80%，冬季产量 61%，夏季产量 38%。
