日本一研究小组在新一期美国《科学》杂志上报告说，一种能使光合作用在近红外线照射下进行的物质——叶绿素D在地球海洋与湖泊中广泛存在，这种叶绿素可能是地球上碳循环的驱动力之一。
此前的研究认为，叶绿素D只存在于少数海洋藻类内部，分布在海洋中很有限的海域，对地球碳循环的作用可以忽略不计。但日本海洋研究开发机构和京都大学联合进行的新研究发现先前的结论有误。
这两所机构发表的新闻公报说，研究人员从北冰洋、日本的相模湾和琵琶湖、南极水域等水温和盐分浓度差异较大的9处水域采集水底堆积物，结果发现，所有堆积物中都含有叶绿素D及其光合作用的产物。
公报说，叶绿素D是吸收波长700纳米至750纳米的近红外线进行光合作用的唯一色素，上述发现说明近红外线在光合作用中得到了利用，而且可能对地球上的碳循环产生了影响。
研究人员估计，若将全球范围内叶绿素D吸收的二氧化碳换算成碳，每年可能约有10亿吨，相当于大气中平均每年二氧化碳增加量的约四分之一。（生物谷Bioon.com）
生物谷推荐原始出处：
Science 1 August 2008;Vol. 321. no. 5889, p. 658;DOI: 10.1126/science.1158761
Evidence of Global Chlorophyll d
Y. Kashiyama,1* H. Miyashita,2 S. Ohkubo,2 N. O. Ogawa,1 Y. Chikaraishi,1 Y. Takano,1 H. Suga,1 T. Toyofuku,1 H. Nomaki,1 H. Kitazato,1 T. Nagata,3 N. Ohkouchi1
Although analyses of chlorophyll d (Chl d)-dominated oxygenic photosystems have been conducted since their discovery 12 years ago, Chl d distribution in the environment and quantitative importance for aquatic photosynthesis remain to be investigated. We analyzed the pigment compositions of surface sediments and detected Chl d and its derivatives from diverse aquatic environments. Our data show that the viable habitat for Chl d-producing phototrophs extends across salinities of 0 to 50 practical salinity units and temperatures of 1 to 40, suggesting that Chl d production can be ubiquitously observed in aquatic environments that receive near-infrared light. The relative abundances of Chl d derivatives over that of Chl a derivatives in the studied samples are up to 4%, further suggesting that Chl d-based photosynthesis plays a quantitatively important role in the aquatic photosynthesis.
1 Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan.
2 Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
3 Center for Ecological Research, Kyoto University, Otsu 520-2113, Japan.
Present address: Ocean Research Institute, University of Tokyo, Tokyo 164-8639, Japan.
