退化设施蔬菜地修复过程中土壤可溶性有机碳与无机氮动态

土壤强还原处理(reductive soil disinfestation,RSD)可以有效修复退化设施蔬菜地土壤,但实施过程中亦会存在可溶性有机碳(DOC)与无机氮(NO3--N和NH4+-N)的淋溶风险。本研究选用水稻秸秆及其制备的生物质炭(biochar,BC)作为修复材料,采用BC、RSD以及RSD+BC三种方法修复退化蔬菜地土壤,探究修复过程中土壤基本性质、DOC与无机氮的动态变化。结果表明,与对照土壤相比,BC处理显著提高了土壤pH、EC和DOC含量(P<0.05),但对土壤NO3--N和NH4+-N无显著影响。对于RSD和RSD+BC处理,土壤NO3--N含量在1~3 d内快速下降,之后维持在较低水平;土壤DOC含量呈先上升后下降趋势,在整个培养时段均显著高于对照处理(P<0.05)。方差分析表明,BC与RSD处理对土壤DOC、全碳(TC)、全氮(TN)和C/N存在交互作用。可见,RSD和RSD+BC处理能有效去除NO3--N,但DOC含量大幅度增加,存在淋溶风险。     

Purification and characterization of glutathione reductase from Scots pine needles

Changes in the excitability of the liverwort Conocephalum conicum L. caused by inhibitors of ionic channels and phosphorylation uncouplers, were examined. Action potentials were triggered by electrical and light stimuli. Tetraethylammonium chloride, an inhibitor of K⁺ channels, completely blocked the ability to generate action potentials. Excitability also disappeared under the influence of MnCl₂ and LaCl₃, inhibitors of Ca²⁺ channels. The participation of Ca²⁺ and K⁺ in the electrogenesis of action potentials in C. conicum is discussed. Treatment with phosphorylation uncouplers induced a gradual disappearance of the metabolic component of the resting potential. It was accompanied by some series of excitations, numbering from several to over a dozen impulses characterized by decreasing amplitudes, after which the organism became totally unexcitable. Dicyclohexylcarbodiimide an inhibitor of H⁺-ATPase, also caused depolarization of the transmembrane potential and disappearance of excitability. The results indicated the participation of a metabolic component in the generation of action potentials in C. conicum .