太阳紫外线辐射及其生物效应

Surface Sunny Ultraviolet Radiation and Biology Effect

紫外 ( UV)辐射在太阳辐射光谱中的谱区范围是在 1 0 0～ 40 0 nm间 ,其能量仅占太阳辐射总量的 8% ,按照不同波长紫外线所起的生物作用 ,可分为三部分 :紫外线A段 ( UV- A) ,波长 32 0～ 40 0 nm,约占太阳辐射总量的 6 % ,这部分生物作用较弱 ,主要是色素沉着作用。紫外线 B段 ( UV- B) ,波长 2 90～ 32 0 nm,约占太阳辐射总量的1 .5 % ,此段对人体影响较大 ,主要作用是抗佝偻病和红斑作用 ,是引起皮肤癌、白内障、免疫系统能力下降的主要原因之一。紫外线 C段 ( UV- C) ,波长 1 0 0～ 2 90 nm,约占太阳辐射总量的 0 .5 % ,由于几乎完全被臭氧层吸收而不能到达地面。以人工发生的紫外线灯进行实验 ,这段紫外线具有最大杀菌力 。

Ultraviolet radiation can be divided into three parts of the sun's radiation spectrum. The wavelengths of UV A radiation range is from 320 to 400 nm. Ozone absorbs very little of this part of the UV spectrum. Ultraviolet A radiation is needed by humans for the synthesis of vitamin D.However,UV A causes photoaging (toughening of the skin),degradation of the immune system, and to a lesser degree, reddening of the skin and cataract formation. Ultraviolet B ranges in wavelength from 290 to 320 nm. Ozone absorbs much of the shorter wavelength radiation, but this absorption weakens as 320 nm is approached. Plants and animals are particularly affected by this part of the UV spectrum. Ultraviolet B can redden the skin (erythema) and reduce vitamin D synthesis in a short term and may cause skin cancer, cataracts, and may degrade the immune system in the long term. Ultraviolet C is characterized by wavelengths of less than 290 nm. Although highly dangerous to plants and animals, this part of the UV spectrum is completely absorbed by stratospheric ozone and does not reach the earth′s surface.