不同氨氮填加量下沉水植物对沉积物DOM荧光特性的影响

采用三维荧光光谱技术，模拟研究了不同氨氮添加量(0，100，200和400 mg/kg)下沉水植物对湖泊沉积物DOM(溶解性有机质)荧光特性的影响.结果表明:不同氨氮添加量下，沉水植物的存在明显增强沉积物DOM荧光强度，其中对类蛋白质和类氨基酸组分荧光强度影响较大(荧光强度分别增大了20%～77%和27%～56%)；而对类腐殖酸和类富里酸组分影响相对较小(荧光强度分别增大了5%～25%和21%～29%). 添加氨氮可增强沉水植物对沉积物DOM荧光强度影响的程度，当添加量为100 mg/kg时，沉水植物生长最旺盛，沉积物DOM中类蛋白质和类氨基酸组分荧光强度增幅最大(分别约77%和56%)；即外源氨氮通过增加沉积物蛋白质和氨基酸含量增强了沉积物有机氮的生物有效性；而在其他添加量下，DOM各荧光组分强度增幅不大，即适当添加外源氨氮，可通过促进沉水植物生长增加沉积物中蛋白质和氨基酸等含量，从而提高沉积物有机氮的生物有效性. 

Effects of Submerged Plants on Fluorescent Characteristics of DOM in Sediments under Different Doses of NH3-N

The effects of submerged plants on the fluorescent characteristics of DOM in sediments were studied using three-dimensional fluorescence spectroscopy under simulated different doses of NH3-N(0,100,200 and 400 mg/kg) conditions.The results showed that under different doses of NH3-N,the fluorescent intensity of DOM in the sediments was obviously enhanced by the existence of submerged plants.Also,the effects on protein-like and amino acid-like substances were stronger than those on humic acid-like and fulvic acid-like substances,especially when extraneous NH3-N existed.The intensity of protein-like substances increased 20%-77%,and the intensity of amino acid-like substances increased 27%-56%.However,the intensity of humic acid-like and fulvic acid-like substances only increased 5%-25% and 21%-29%,respectively.Under the 100 mg/kg dose of NH3-N,the submerged plants grew best,and the increased amplitude of fluorescence intensity of protein-like and amino acid-like substances in DOM in sediments reached a maximum(about 77% and 56%,respectively).The increase of protein and amino acid contents in the sediments resulting from extraneous NH3-N enhanced the bioavailability of dissolved organic nitrogen in the sediments.Otherwise,under other dose treatments,there were few increased amplitudes of fluorescent intensity of different constituents of DOM.Under proper dosing of extraneous NH3-N,the bioavailability of dissolved organic nitrogen in the sediment would be enhanced through the increase of contents of protein and amino acids resulting from the growth of submerged plants.