Comparison of the effects of short-term UVB radiation exposure on phytoplankton photosynthesis in the temperate Changjiang and subtropical Zhujiang estuaries of China
Comparison of the effects of short-term UVB radiation exposure on phytoplankton photosynthesis in the temperate Changjiang and subtropical Zhujiang estuaries of China
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DOI：
10.1007/s10872-009-0053-5
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发表时间：
2009-11
影响因子：
2.3
通讯作者：
Weihua Zhou;K. Yin;Xiangcheng Yuan;X. Ning
中科院分区：
文献类型：
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作者：
Weihua Zhou;K. Yin;Xiangcheng Yuan;X. Ning
2002年8月至2003年4月，我们研究了太阳紫外线B（UVB，280-315 nm）对东海（ECS）温带长江口（CRE）和南海（SCS）亚热带珠江口（ZRE）天然浮游植物群落光合作用的影响。UVB的短期影响 通过将石英管/瓶中的样品在三种处理下暴露于太阳辐射来评估：(1) 自然光 (NS) 与 UVB (NS-UVB)； (2)光合有效辐射(PAR、NS截断UVB)； (3) NS 加上人工 UVB (NS + A-UVB)。太阳 UVB 明显抑制了浮游植物的光合作用速率。在温带 CRE-ECS 中，8 月和 2 月，太阳 UVB 使表面浮游植物光合作用减少了约 28%，而在亚热带 ZRE-SCS 中，9 月和 10 月的抑制仅为 22%。在 CRE-ECS 中，当较深的水样暴露于表面 UVB 时，分层水柱中的浮游植物表现出更强的 UVB 抑制作用。混合水体中的浮游植物没有表现出强烈的UVB抑制作用，而同一水体中较深的浮游植物的光移暴露到表面光产生了类似的结果，表明混合缓和了UVB效应。在ZRE-SCS，表层浮游植物在一月份（晴天）表现出更大的光抑制作用。然而，4月（多云），浮游植物对UVB的抑制作用甚微。在没有 UVB 的情况下进行短时间的孵化表明，ZRE-SCS 中两个站的 Chlaat 大幅增加，但在存在 UVB 的情况下，另一个站的 Chlaat 大幅减少。相比之下，在 CRE-ECS 中，没有 UVB 的类似孵化实验显示 Chla 减少，并且 Chlaat 两个站的 UVB 抑制较小。营养条件可能在两个区域之间的 UVB 抑制差异中发挥了作用，因为 ZRESCS 的所有营养物质浓度相对较高，而 CRE-ECS 站之一的 PO4 仅 0.21 µM。结果表明，温带水域的浮游植物比亚热带水域的浮游植物对 UVB 的变化更敏感。
We examined the effect of solar ultraviolet radiation B (UVB, 280–315 nm) on photosynthesis of natural phytoplankton assemblages in the temperate Changjiang River Estuary (CRE) in the East China Sea (ECS), and the subtropical Zhujiang River Estuary (ZRE) in the South China Sea (SCS) from August 2002 to April 2003. The short-term effect of UVB was assessed by exposing samples in quartz tubes/bottles to solar radiation under three treatments: (1) natural sunlight (NS) with UVB (NS-UVB); (2) photosynthetically active radiation (PAR, NS cut off UVB); and (3) NS with additional artificial UVB (NS + A-UVB). Solar UVB apparently inhibited phytoplankton photosynthesis rates. In the temperate CRE-ECS, solar UVB reduced surface phytoplankton photosynthesis by about 28% in August and February, while in the subtropical ZRE-SCS the inhibition was only 22% in September and October. In the CRE-ECS, phytoplankton in the stratified water column displayed stronger UVB inhibition when deeper water samples were exposed to surface UVB. Phytoplankton in the mixed water column did not show strong UVB inhibition, while light shift exposure of deeper phytoplankton in the same water column to surface light produced similar results, indicating that mixing moderates UVB effects. In the ZRE-SCS, surface phytoplankton showed greater photoinhibition in January (sunny). However, in April (cloudy), phytoplankton showed little UVB inhibition. Incubation for a short time without UVB showed a large increase in Chlaat two stations in the ZRE-SCS, but a large decrease at the other station in the presence of UVB. In contrast, in the CRE-ECS, a similar incubation experiment without UVB showed a decrease in Chla, and small UVB inhibition of Chlaat two stations. Nutrient conditions might have played a role in the difference of UVB inhibition between the two regions as the ZRESCS had relatively high concentrations of all nutrients while PO4was only 0.21 µM at one of the CRE-ECS stations. The results suggest that phytoplankton in temperate waters would be more responsive to variation of UVB than ones in subtropical waters.