What color should glacier algae be? An ecological role for red carbon in the cryosphere
What color should glacier algae be? An ecological role for red carbon in the cryosphere
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DOI：
10.1093/femsec/fiy007
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发表时间：
2018-03-01
影响因子：
4.2
通讯作者：
Skiles, S. McKenzie
中科院分区：
文献类型：
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作者：
Dial, Roman J.;Ganey, Gerard Q.;Skiles, S. McKenzie
冰川藻类中红色的次生色素在冰雪融化中起到了适应性作用。我们利用基于颜色的辐照度吸收模型、雪中有色颗粒的实验以及冰川藻类的自然历史提出了这一假设。雪藻中的类胡萝卜素和酚类虾青素以及冰藻中的紫红没食子酸酯通过吸收过量的可见光波长，然后将多余的辐射能量以热量的形式消散，从而屏蔽了光合作用。这种热量融化了近端的冰晶，在0摄氏度的环境中提供了液态水，并释放了结合在冰水中的营养物质。我们发现，紫色粒子传递了黑色粒子吸收的太阳能的87%-%。然而，红色粒子通过吸收峰值太阳波长和反射被附近冰雪晶体吸收最多的可见光波长来传递几乎同样多的(85%-87%)；后一种过程可能会减少雪绝缘细胞时潜在的细胞过热。蓝色和绿色颗粒只转移了黑色颗粒吸收的80%-82%。在实验中，红色颗粒融化的雪量是黑色颗粒的87%，而蓝色颗粒融化的雪量为77%。绿色的雪藻自然占据了水无限的饱和雪地；红色的雪藻占据了更干燥、水分有限的雪。除了增加融化，我们认为雪藻细胞中的酯化虾青素增加了疏水性以保持表面。
Red-colored secondary pigments in glacier algae play an adaptive role in melting snow and ice. We advance this hypothesis using a model of color-based absorption of irradiance, an experiment with colored particles in snow, and the natural history of glacier algae. Carotenoids and phenols-astaxanthin in snow-algae and purpurogallin in ice-algae-shield photosynthetic apparatus by absorbing overabundant visible wavelengths, then dissipating the excess radiant energy as heat. This heat melts proximal ice crystals, providing liquid-water in a 0 degrees C environment and freeing up nutrients bound in frozen water. We show that purple-colored particles transfer 87%-89% of solar energy absorbed by black particles. However, red-colored particles transfer nearly as much (85%-87%) by absorbing peak solar wavelengths and reflecting the visible wavelengths most absorbed by nearby ice and snow crystals; this latter process may reduce potential cellular overheating when snow insulates cells. Blue and green particles transfer only 80%-82% of black particle absorption. In the experiment, red-colored particles melted 87% as much snow as black particles, while blue particles melted 77%. Green-colored snow-algae naturally occupy saturated snow where water is non-limiting; red-colored snow-algae occupy drier, water-limited snow. In addition to increasing melt, we suggest that esterified astaxanthin in snow-alga cells increases hydrophobicity to remain surficial.