自然光和UV辐照下二级出水DOM及毒性的变化

为了探明自然光和紫外光（UV）对二级处理出水中溶解性有机物（DOM）及其毒性效应的削减特性，研究了在自然光和UV两种不同光源的辐照条件下，二级处理出水中DOM的光谱特性、遗传毒性和植物毒性变化，阐明了毒性效应变化的成因.结果表明：相比于自然光照，UV辐照可以明显降低二级处理出水的UV₂₅₄，并达到21%矿化.自然光和UV均可降低二级处理出水中有色溶解性有机物（CDOM），但去除的组分有所差异.同时，自然光照与UV辐照均可降低二级处理出水的遗传毒性，其削减率分别达到92%和61%.遗传毒性的变化与CDOM荧光强度变化有显著相关性.UV辐照可降低二级处理出水的植物毒性，削减率达到81%，而自然光照对二级处理出水植物毒性的削减率仅为19%，削减效果较差.利用UPLC-MS检测二级出水中的除草剂，发现植物毒性削减的差异主要是由于自然光照下二级处理出水中的阿特拉津降解缓慢，表观降解速率常数为0.0033h^-1；但是UV辐照下二级处理出水中的阿特拉津可快速降解，其表观速率常数为0.2225h^-1.这为污水厂排放水毒性效应控制及生态安全保障提供了一定的依据.

Variation of dissolved organic matter and its biotoxicity from secondary effluent under sunlight and ultraviolet light irradiation

In order to investigate the variation of dissolved organic matter (DOM) and related biotoxicity from secondary effluent, this paper studied the spectral characteristics, genotoxicity and phytotoxicity of DOM from secondary effluent under the photolysis condition of sunlight and ultraviolet light (UV) irradiation. The origin of biotoxicity from DOM was also explored. The results showed that UV irradiation could significantly decrease UV₂₅₄ value and achieve 21% of mineralization, comparing with sunlight irradiation. Both sunlight and UV irradiation could reduce the chromophoric dissolved organic matter (CDOM), but the obviously removed components were different. Meanwhile, the sunlight and UV irradiation could also reduce genotoxicity posed by secondary effluent and their removal efficiencies were 92% and 61%, respectively. Genotoxicity from secondary effluent was significantly correlated with fluorescence intensity of CDOM. UV irradiation could reduce 81% of phytotoxicity posed by secondary effluent. However, sunlight irradiation showed a poor property on phytotocicity removal (only 19%). UPLC-MS was used to detect herbicides from secondary effluent. It was found that the difference in phytotocicity removal was mainly due to the slow degradation of atrazine in secondary effluent under sunlight irradiation, and its apparent rate constant was 0.0033h^-1. However, atrazine could be rapidly degraded under UV irradiation, whose apparent degradation rate constant was 0.2225h^-1. This provides a certain basis for the biotoxicity control and ecological safety of discharged wastewater from wastewater treatment plant.