中亚热带常绿阔叶林湿沉降过程中盐基离子变化特征

Dynamic Characteristics of Base Cations During Wet Deposition in Evergreen Broad-leaf Forest Ecosystem

基于野外实验和室内实验相结合的方法,于2012年9月至2013年8月对四面山常绿阔叶林大气降水、穿透水、地表枯透水、土壤渗滤液进行了持续一年的森林不同层次盐基离子季节动态变化特征的研究.结果表明,四面山大气降水全年pH平均值为4.90,最大值为5.14,大气降水明显偏酸性;土壤层和林冠层能使降雨的p H值有所升高,其中土壤层对p H值的调升幅度最大,其次为森林冠层;森林冠层只对Na^+有一定的截留作用,降雨能够淋溶森林冠层的Ca^(2+)、Mg^(2+)、K^+;研究结果也表明,枯枝落叶的降解是导致各盐基离子质量浓度在枯透水中增加的主要原因;枯透水下渗的过程淋溶了森林土壤中的Ca^(2+)、Mg^(2+)、Na^+.四面山大气降水经过森林生态系统后Ca~(^(2+))、Mg^(2+)、Na^+、K^+的总截留率分别为33.82%、-7.06%、74.36%、42.87%,森林生态系统对Ca^(2+)、Na^+、K^+表现出了截留作用,其中对Na^+截留率最大.

Based on field tests and laboratory experiments,effects of precipitation,throughfall,litterfall,and groundwater runoff of the ever-green broad-leaf forest on the dynamic characteristics of base cations in Simian Mountain were investigated from September 2012 to August 2013. The results showed that the rainfall of Simian Mountain was apparently acidic,with average pH of 4. 90 and maximum p H of 5. 14. The soil and canopies could increase p H of precipitation,with soils having the maximum increment,followed by the forest canopy. Forest canopy only had the function of interception on Na^+. And precipitation could leach out Ca^(2+),Mg^(2+)and K^+ of the canopies. Moreover,the degradation of litter was probably the main reason for the increase of base cations concentrations in the surface litter water. The litter water leached Ca^(2+),Mg^(2+)and Na+of the forest soil through downward infiltration. The total retention rates of Ca^(2+),Mg^(2+),Na^+ and K^+were 33. 82%,- 7. 06%,74. 36% and 42. 87%,respectively. Ca^(2+),Na^+,K^+ were found to be reserved in the forest ecosystem,and the highest interception rate was found for Na^+.