长江中下游浅水湖泊紫外辐射的衰减

The attenuation of ultraviolet radiation in shallow lakes in the middle and lower reaches of Yangtze River

基于对长江中下游22个浅水湖泊有色可溶性有机物吸收的测量,运用经验模式估算了紫外辐射(UV-B、UV-A)在长江中下游湖泊的衰减及对应的穿透深度,并利用在武汉东湖实测的紫外辐射衰减进行了检验.结果表明,UV-B波段的320nm和UV-A波段的380nm衰减系数变化范围分别为2.05～21.00m-1,1.07～12.85m-1,对应的1%穿透深度分别为0.22～2.25m,0.36～4.29m.估算得到的紫外辐射衰减系数与DOC浓度均存在显著性正相关,但UV-B波段要高于UV-A波段.武汉东湖实测的紫外辐射衰减检验发现,基于CDOM吸收系数估算UV-B辐射衰减较为精确,而由于浮游植物吸收和悬浮物散射等影响对UV-A波段估算精度则明显下降.

Based on the measurement of chromophoric dissolvable organic matter in 22 shallow lakes in the middle and lower reaches of Yangtze River, the attenuation of ultraviolet radiation （UV-B, UV-A） in the lakes in the middle and lower reaches of Yangtze River and corresponding penetrating depth were estimated using empirical models; and checked up utilizing the field measured attenuation of ultraviolet radiation in Lake Donghu Wuhan. The change range of attenuation coefficients of UV-B wave band （320nm） and UV-A wave band （380nm） was 2.05-21.00m^-1 and 1.07-12.85m^-1 respectively; and the corresponding 1% penetrating depths were 0.22-2.25m and 0.36-4.29m respectively. The estimated ultraviolet radiation attenuation coefficient and DOC concentration all existed markedly positive relationship; but UV-B wave band was higher than UV-A wave band. The field check of ultraviolet radiation attenuation in Lake Donghu, Wuhan showed that the estimation of attenuation of UV-B radiation was more accurate based on CDOM coefficient; while the estimation accuracy of UV-A wave band decreased obviously due to the influence of phytoplankton absorption and suspended substance scattering.