UV-B辐射下悬沙对小球藻生长和DNA损伤的影响

研究了UV-B辐射(17μW cm-2,5 min/d)下不同浓度(0、100和1 000 mg L-1)和粒径组成(全粒径组和粒径<38μm组)的悬沙对小球藻(Chlorella sp.)生长和DNA损伤的影响.结果显示,小球藻的生长可用Logistic增长模型拟合,拟合后的生长参数表明悬沙的"遮荫效应"减轻了UV-B辐射对小球藻细胞的DNA损伤,从而对小球藻生长产生正影响.悬沙浓度越高,UV-B辐射对小球藻细胞DNA损伤程度越低,小球藻的环境负载能力a和瞬时增长率K越大.当悬沙浓度为100 mg L-1时,全粒径组a值和K值小于粒径<38μm组,且两组间小球藻细胞DNA损伤差异显著(P<0.05),但当悬沙浓度达1 000 mg L-1时,全粒径组a值和K值大于粒径<38μm组,两组间细胞的DNA损伤无显著差异(P>0.05).图3表2参24

Effects of Suspended Solids on Growth and DNA Damage of Chlorella sp. Exposed to UV-B Radiation

Effects of suspended solids(SS) with different concentrations(0,100 and 1 000 mg L-1) and different particle sizes(all size range and size < 38 μm) on the growth and DNA damage of Chlorella sp.exposed to UV-B radiation(17 μW cm-2,5 min/d) were studied.The growth of Chlorella sp.was well predicted by a logistic model,and the growth parameters showed that,SS attenuated DNA damage induced by UV-B and promoted the cell growth.With the increase of SS concentration,the cellular DNA damage induced by UV-B decreased,and the environmental carry capacity(a) and instantaneous rate of increase(K) increased.When the cells were exposed to SS of 100 mg L-1,the values of a and K were lower in all-size-range group than in the group of size < 38 μm,and a significant difference in the cellular DNA damage(P < 0.05) appeared between them.When exposed to SS of 1 000 mg L-1,a and K were higher in all-size-range group than in the group of size < 38 μm,but no significant difference in the cellular DNA damage(P > 0.05) was found.Fig 3,Tab 2,Ref 24