日本一研究小組在新一期美國《科學》雜志上報告說,，一種能使光合作用在近紅外線照射下進行的物質——葉綠素D在地球海洋與湖泊中廣泛存在,，這種葉綠素可能是地球上碳循環(huán)的驅動力之一。
此前的研究認為,，葉綠素D只存在于少數(shù)海洋藻類內部,，分布在海洋中很有限的海域，對地球碳循環(huán)的作用可以忽略不計,。但日本海洋研究開發(fā)機構和京都大學聯(lián)合進行的新研究發(fā)現(xiàn)先前的結論有誤,。
這兩所機構發(fā)表的新聞公報說，研究人員從北冰洋,、日本的相模灣和琵琶湖,、南極水域等水溫和鹽分濃度差異較大的9處水域采集水底堆積物,，結果發(fā)現(xiàn)，所有堆積物中都含有葉綠素D及其光合作用的產物,。
公報說,，葉綠素D是吸收波長700納米至750納米的近紅外線進行光合作用的唯一色素，上述發(fā)現(xiàn)說明近紅外線在光合作用中得到了利用,，而且可能對地球上的碳循環(huán)產生了影響,。
研究人員估計，若將全球范圍內葉綠素D吸收的二氧化碳換算成碳,，每年可能約有10億噸,，相當于大氣中平均每年二氧化碳增加量的約四分之一。（生物谷Bioon.com）
生物谷推薦原始出處：
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.
