Dark brown forest soil was collected from the upper 20 cm soil layer in Changbai Mountain Research Station of Ecosystem, Chinese Academy of Sciences. The soil was amended with two different forms of nitrogen fertilizers: NO3- as Ca(NO3)2, NH4+ as NH4Cl at the concentrations of 50, 100, 200 and 400 mgkg-1 respectively. The experiment was carried out with 2-yr-old Pinus koraiensis seedlings in pot. The pH change of rhizosphere soil and the contents of available Fe, Mn, Cu, and Zn in soil and leaves were analyzed. The result indicated that the addition of NH4--N decreased the rhizosphere pH value, while the addition of NO3--N increased the rhizosphere pH value in contrast with the control treatment. The direction and extent of the pH change mainly depended on N source and its concentrations applied. The rhizosphere pH change had a remarkable influence on the availability of the micronutrients in the rhizosphere, and thereafter affected the nutrient uptake by the seedlings. The contents of available mineral nutrients had a negative correlation with the pH value in the rhizosphere soil. The contents of available mineral nutrients in leaves were positively correlated to the levels of the available nutrients in the rhizosphere soils.
电吸附除盐技术是一种新型的饮用水处理技术,具有能耗低、无二次污染和电极可重复利用等优点。采用活性炭纤维(ACF)作为电极材料对其电吸附去除水中的硝酸盐进行了研究,考察了电压、pH、流速、初始浓度等因素对电吸附效率的影响以及超声处理对电极脱附和再次利用的影响。结果表明,电吸附作用对硝酸盐的去除有较高的效率,最佳的工艺条件为:电压1.0 V,pH为5.0~6.0,进水流速10 m L·min^(-1),初始NO_3^--N浓度为25~30 mg·L^(-1),在该条件下硝酸盐去除效率为68.3%~72.62%。超声处理对电极的脱附作用和再生效率有较大的改善和提高,超声处理过的电极比未处理的电极对硝酸盐的去除率可提高16.10%~18.98%。
