鼎湖山典型森林地表卤代烃通量对氮沉降的响应  

Responses of volatile halogenated organic compounds fluxes from forest floor to simulated nitrogen deposition in Dinghushan

作　　者：吴旺旺 郑丽丽[1] 黄幸然[1] 胡宝叶 易志刚[1] 

机构地区：[1]福建农林大学资源与环境学院,福州350002

出　　处：《生态学杂志》2016年第5期1147-1153,共7页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(41473083;41173090)资助

摘　　要：卤代烃(volatile halogenated organic compounds,VOX)是一类已被公认的大气环境污染物,能导致臭氧层空洞和温室效应。虽然海洋是卤代烃主要的源汇区,但是森林生态系统地表卤代烃通量对全球卤代烃循环也存在着重要贡献。全球氮沉降量逐年增加,严重影响森林生态系统的结构与功能,从而导致地表卤代烃源汇发生改变。本研究运用静态箱及大气预浓缩仪-GC-MS系统分析了鼎湖山马尾松林(PF)和季风常绿阔叶林(BF)地表卤代烃通量及其对氮沉降的响应。结果表明:自然氮沉降下,马尾松林地表为卤代烃的汇,吸收速率最大的化合物为1,1,2-三氯乙烷,达-428.32 pmol·m-2·s-1;施氮促进卤代烃排放,且中氮效果显著,地表由"汇"变成"源";阔叶林地表为卤代烃的源,氮增加抑制其排放,部分卤代烃由"源"变为"汇",对照样地与氮处理样地存在显著差异。自然氮沉降下,林型间卤代烃通量存在显著差异,加氮后差异减弱甚至消失。加氮处理样地,马尾松林中氯乙烯与1,2-二氯丙烷、1,1,2-三氯乙烷显著相关,阔叶林中氯甲烷与氯乙烯、氯乙烷及氯苯显著相关,而氯苯与大部分被测卤代烃都具有显著的相关性,说明部分卤代烃对氮沉降可能有相同的响应机制。自然氮沉降下,阔叶林卤代烃通量日变化无明显规律,但高氮处理样地,各化合物表现基本一致,在07:00出现释放小高峰,最大吸收则主要出现在13:00。Volatile halogenated organic compounds （VOX） are known as atmospheric pollutants which contribute to stratospheric ozone depletion and global warming. Although ocean is consi- dered to be the major source and sink of VOX, VOX from forest ecosystems still have significant effect on global VOX cycle. Increasing global nitrogen deposition plays a great role in structure and function of forest ecosystems, leading to changing of VOX uptake and emission from forest floor. Static chamber coupled with preconcentrator-GC-MS technique was employed to study the responses of VOX fluxes from forest floor with simulated elevated nitrogen deposition in two major forests, namely pine forest （PF） and monsoon evergreen broadleaf forest （BF） in Dinghushan. The results showed that PF floor acted as sink for VOX at the control sites, with the maximum uptake rate of-428.32 pmol m-2 s-1 for 1,1,2-trichloroethane. The uptake rates of VOX de- creased with enhanced nitrogen deposition, and the medium nitrogen addition had a significant influence on VOX flux in PF, with the change from sink to source. BF floor acted as source for VOX at the control sites. The emission rates of VOX decreased with enhanced nitrogen deposi- ests at the control sites, but the difference diminished or even disappeared with nitrogen addition. Significant correlations were observed between vinyl-chloride and 1, 2-dichloropropane and 1,1,2-trichloroethane at nitrogen addition sites in PF. In BF, significant correlations were also found between chloromethane and vinyl-chloride, chloroethane and chlorobenzene, and between chlorobenzene and most tested VOXs. These results indicated the same mechanism of response of the tested VOXs to nitrogen deposition in forest floor. There were no obvious diurnal variations for VOX fluxes at the control site, but a small emission peak appeared at 07：00 and the highest up- take rates were observed at 13：00 for most of the VOXs at high nitrogen addition sites in BF.

关 键 词：卤代烃 氮沉降 森林 挥发性有机化合物 鼎湖山 

分 类 号：S718.5[农业科学—林学]