【摘要】 为了解硝酸根（NO₃^-）的光化学活性对水体中有机磷间接光解释放磷酸根过程的影响,采用室内模拟实验,研究了NO₃^-在草甘膦光解转化为磷酸根中的作用及NO₃^-浓度对该反应速度的影响,并以甲醇为羟基自由基（·OH）猝灭剂,印证了NO₃^-对富营养化湖泊水体中有机磷光解释放磷的作用.结果表明,在紫外光（UV）照射下,草甘膦可以直接光解转化为磷酸根,其磷酸根的释放量随着溶液初始p H和草甘膦浓度的增加而增大.加入NO3^-处理,光照60min后,磷酸根的释放量由空白处理的0.05mg/L增加到了0.43mg/L.添加Fe³⁺可促进这一过程,而添加腐殖酸（HA）和碳酸氢根（HCO₃^-）则可以显著抑制磷酸根的释放.在湖泊水体中,添加草甘膦,磷酸根的释放量显著高于空白,而增加湖水中NO₃^-浓度时,磷酸根的释放量则进一步增大.在湖水/草甘膦/NO₃^-体系中添加·OH猝灭剂甲醇后,磷酸根的释放量显著降低.可见在紫外光条件下,NO₃^-的光化学作用对有机磷释放磷酸根过程具有重要影响.更多还原

【Abstract】 In order to understand the influence of nitrate（NO₃^-） photochemical activity on the phosphate released from organic phosphorus indirect photolysis degradation, the phosphate released from glyphosate photodegradation by NO₃^- was investigated in deionised and natural water under UV irradiation. Meanwhile, the methanol was used as the ?OH scavenger to confirm the role of NO₃^- on the phosphate released from organic phosphorus degradation in the natural eutrophication lakes. The results showed that the phosphate could be released from glyphosate photolysis under UV irradiation and the release amount of phosphate increased with p H and initial concentration of glyphosate increasing under UV light irradiation in deionised water. NO₃^- adding enhanced the phosphate released from glyphosate photodegradation in comparison with direct photolysis and the concentration of phosphate increased from 0.05mg/L to 0.43mg/L with the 20mg/L NO₃^- added to the solution under UV irradiation for 60 min. The effect of environmental parameters including Fe³⁺, HCO₃^- and humic acid on the phosphate released from glyphosate photodegradation by NO₃^- was also performed. In the presence of Fe³⁺, the amount of phosphate released from glyphosate photodegradation increased significantly due to photosensitization by reactive species such as hydroxyl radical. The presence of humic acid and HCO₃^- inhibited phosphate released through a radical scavenging effect. The release amount of phosphate in the natural water with NO₃^- spiked is higher than that of control and the phosphate released was inhibited when the methanol was added to the reaction system. All these results reveal that NO₃^- plays an important role in phosphate released from organic phosphorus photodegradation.更多还原