新时代土壤化学前沿进展与展望

土壤化学是重要的土壤学基础分支学科。在回顾了土壤化学发展历程的基础上,梳理了土壤化学的四个前沿交叉方向,并展望了土壤化学与其他相关学科的交叉发展趋势,以期寻求新的学科增长点。土壤化学经历了从恒电荷到可变电荷土壤学说演变,我国在土壤电化学、根际土壤化学、土壤化学-物理-微生物界面反应等方向逐步领跑。新时代中国已经发展成为国际土壤化学的研究中心之一,尤其在土壤化学与微生物学、地球化学、矿物学、环境化学等交叉领域取得了突破性发展。同时,发展并运用同步辐射、微流控联用光谱能谱、高分辨显微镜、光谱电化学等实时、原位、高精度研究方法,推动土壤化学研究取得了长足的进步。新时代的土壤化学具有三个重要发展趋势,首先系统揭示地球表层系统中物质循环与能量交换的土壤化学机制,实现"0到1"的土壤化学原创性成果的突破;其次需要综合运用地球表层系统理论,从多界面、多要素、多过程的"三多"交互耦合;再次,需要加强与地球宜居性这一人类重大命题的交叉融合,为生态文明建设、土壤污染防治攻坚战、全球变化等国家重大需求提供理论支持。     

Nitrogen reduction stimulated by a three-dimensional electrochemical-biofilm reactor and its correlation with electric field

To realize automatic control, it is important to study the response of reactor to electric field. A three-dimensional biofilm eletrode reactor is developed and steadily operated to remove nitrogen. In the reactor, oxygen is produced on the anode and hydrogen is produced on the cathode of the three-dimensional electrode by electrolysis water. Microorganism in the reactor utilize oxygen and hydrogen adequately to remove nitrogen by nitrification-denitrification. To evaluate the correlation of electric field with the reactor, DO, pH and nitrogen removal efficiency are studied. Results show that when a electric field of 0.013 4 mA/cm 2 is applied to the system, the removal rate of NH +4-N, NO -3-N and TN is 90%, 70% and 70%, respectively. To assure the reactor run efficiently, the maximum of the intensity of electric field applied to the reactor is 0.0201 mA/cm 2. Within 0.0201 mA/cm 2, the system is in stable running status, while DO and pH is altered resulting from the intensity of electric field. With enhancing the intensity of electric field, the removal rate of NO -3 -N can be improved, although, the removal rate of NH +4-N is not elevated markedly. There is no accumulation of NO -2 -N within 0.0201 mA/cm 2.     

采用石墨-无机硅胶复合阳极的土壤MFC产电性能研究

土壤微生物燃料电池（MFC）可以将土壤产电细菌分解有机质产生的化学能转化为电能。为了提高土壤MFC的产电性能，实现持续稳定驱动小功率用电器，本研究发明一种新型复合材料作为阳极，在水稻土中构建了土壤MFC。通过串联两个土壤MFC，将输出电压维持在1 403.3~1 579.9 mV，实现持续驱动电子计时器稳定运行30 d。之后移除电子计时器进行土壤MFCs的电化学测试。功率密度曲线显示串联土壤MFCs最大功率密度5.45 mW·m^-2，最大输出功率158.42 μW。电化学阻抗谱分析表明，单个土壤MFC阳极电荷传递电阻分别为16.46 Ω和16.80 Ω。从阳极表面的土壤样品中提取RNA，对逆转录后的16S rRNA进行测序分析。结果显示，土壤MFCs中，阳极上有14个产电细菌相关属，其中地杆菌属（Geobacter）、芽孢杆菌属（Bacillus）、梭菌属（Clostridium）、假单胞菌属（Pseudomonas）和脱硫球茎菌属（Desulfobulbus）16S rRNA的数量均占所有产电细菌相关属总数的10%以上，为最活跃的产电细菌相关属。     

生物电化学中的广义氧化还原电位缓冲体系

 根据广义氧化还原理论,发现生物体内存在电位缓冲体系。并给出电位的计算公式,分析了影响缓冲体系电位的主要因素。