增强的UV-B对湖泊生态系统的影响研究

EFFECTS OF INCREASED UV-B RADIATION ON AQUATIC ECOSYSTEMS IN LAKES

近 2 0多年来 ,由于平流层臭氧层减薄引起紫外辐射 (UV B)增强而导致严重的生态学后果 ,已受到各国广泛的重视 ,并对此进行了深入研究 ,尤其集中在海洋浮游植物初级生产者及淡水食物网上。综述了国外在UV B对湖泊生态系统影响的研究现状与动态 ,增强的UV B在湖泊中呈指数衰减 ,不同湖泊衰减系数变化很大 ;光衰减系数与溶解性有机碳 (DOC)、有色可溶性有机物(CDOM)一般呈显著性正相关 ;增强的UV B对浮游植物、浮游细菌、浮游动物及鱼类均有不同程度的影响 ;由于不同生物具有不同适应UV B伤害的机制 ,湖泊生态系统的结构和功能也势必会发生变化。最后提出了未来在太湖等富营养化湖泊UV

In the past 20 years, the decrease in stratospheric ozone concentrations has provoked an increase of UV-B radiation in the wavelength range from 280 to 320nm. The ecological effects of increased UV-B on global environment attract more and more scientific studies. This paper demonstrates the advances of effects of UV-B radiation on aquatic organisms and aquatic ecosystems in lakes. The penetration of UV-B radiation into lakes is highly dependent on the concentration of dissolved organic carbon (DOC) and chromophoric dissolved organic matter(CDOM) in the water body. Many empirical regression relationships between the concentration of DOC and the diffuse attenuation coefficient, the euphotic depth (1% of surface irradiance) were found in many studies. Many studies demonstrate a variety of aquatic organism ranging from bacterioplankton and phytoplankton to zooplankton, and even aquatic vertebrates such as fish are vulnerable to damage from increased UV-B radiation. In general, aquatic organisms have three levels responses to minimize the exposure to UV-B: 1 behavioral avoidance, 2 manufacture or sequester UV-B absorbing compounds, 3 DNA repair mechanisms. Some assumptions about the effects of UV-B radiation on Lake Taihu ecosystem are presented.