Suwannee河腐植酸光化学生成溶解无机碳的研究

Photoproduction of Dissolved Inorganic Carbon from Suwannee River Humic Acid

溶解有机质矿化为溶解无机碳是全球碳循环中的一个重要过程.利用模拟太阳光对Suwannee河腐植酸的光氧化过程模拟,研究了溶解氧浓度、模拟太阳光波长范围和铁浓度对溶解无机碳产量的影响.研究表明,基于前24 h空气饱和的无机碳矿化速率4.40μmol/(L.h),氧气饱和条件下照射增加1.56倍,氮气饱和条件下照射下降36%.UV-B,UV-A和可见光部分分别占溶解无机碳产量的31.8%、32.6%和25.6%.当加入20μmol/L铁络合剂DFOM时(初始样品Suwannee河腐植酸铁含量为5.46μmol/L),溶解无机碳产量下降55.6%.

The photochemical mineralization of dissolved organic carbon to dissolved inorganic carbon（DIC） is a key process in carbon cycling.Suwannee river humic acid was photooxidated using a Suntest CPS solar simulator to examine the effects of dissolved oxygen levels,the wavelength of incident light and the concentration of Fe on the photoproduction of DIC.Based on the rate of DIC photoproduction under air-saturation in the first 24 h（4.40 μmol/（L·h））,it increased by a factor of 1.56 under O2-saturation,but fell by only 36% under N2-saturation.UV-B,UV-A and visible wavelengths accounted for 31.8,32.6 and 25.6% respectively of DIC production.As 20 μmol/L DFOM added,the rate of DIC photoproduction was 55.6% of that of original Suwannee river humic acid samples with 5.46 μmol/L Fe.