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

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 2.05-21.00 m-1 and 1.07-12.85 m-1 respectively; and the corresponding 1% penetrating depths were 0.22-2.25 m and 0.36-4.29 m 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.