Assessment of the Effects of Ultraviolet Radiation on Phytoplankton in Antarctic Waters

南极目前正在经历30%至50%的平流层臭氧层春季损失，导致到达南大洋表面的UVB(280-320 nm)辐射至少增加了几倍。尽管太阳高度较低，云层持续存在，但极地地区现在经历的紫外线辐射注量率的大小大致接近热带纬度地区常规测量的水平。也许更重要的是，生物破坏性的UVB辐射在南极增加了，而UVA(320-400 nm)和光合作用有效辐射(PAR，400-700 nm)都保持不变。这一合作项目将利用最近在大气模拟和水中紫外线和可见光辐射计方面取得的改进，在1990年春季进行实地研究。入射和穿透南极边缘冰缘真光层的UVB：UVA：PAR辐照度的大小和比率的逐日变化将是合格的。在冰缘春季水华期间，紫外线辐射的增加对浮游植物群落的丰度、组成和活力的影响将被记录在案。在此期间，强烈的垂直层结将浮游植物限制在上层水柱，从而为UVB敏感性的增加创造了有利条件。将特别强调确定增强的UVB辐射和改变的UVB：UVA：PAR比率施加的生物限制，以平衡UVB光损伤与光修复、光保护和光合作用机制在水柱中的作用。总体目标是对南极水域浮游植物不受臭氧消耗不利影响的假设进行客观测试。

The Antarctic is currently experiencing a thirty to fifty percent springtime loss of its stratospheric ozone layer, resulting in a least a several-fold increase in UVB (280-320nm) radiation reaching the surface of the Southern Ocean. In spite of low solar elevation and persistent cloud cover, the magnitude of ultraviolet radiation fluence rates now experienced in polar regions roughly approaches that routinely measured in tropical latitudes. Perhaps more importantly, biologically damaging UVB radiation has increased in the Antarctic while both UVA (320- 400nm) and photosynthetically available radiation (PAR, 400- 700nm) have remained unchanged. This collaborative project will use recently developed improvements in atmospheric modeling and in-water UV and visible spectroradiometers to conduct a field study during austral spring 1990. The day-to-day variations in the magnitude and ratio of UVB:UVA:PAR irradiance incident on and penetrating the euphotic zone of marginal ice edge Antarctic waters will be qualified. The impact of this increase of UV radiation on abundance, composition and vitality of the phytoplankton community during the ice-edge spring bloom will be documented. During this time, strong vertical stratification restricts the phytoplankton to the upper water column, thus creating favorable conditions for increased UVB susceptibility. Special emphasis will be placed on defining biological restraints imposed by enhanced UVB radiation and altered UVB:UVA:PAR ratios on the balance of UVB photodamage to photorepair, photoprotective and photosynthetic mechanisms operating in the water column. The overall aim is an objective test of the hypothesis that phytoplankton in Antarctic waters are adversely unfluenced by ozone depletion.