CAJ | 학술논문

苯系物（BTEX）是一类重要的挥发性有机化合物（VOCs），能参与大气光化学反应，并对人体健康有重要影响。土壤能释放或吸收BTEX，氮沉降会影响土壤生态过程，从而可能影响土壤BTEX通量。有关森林土壤BTEX通量对氮沉降响应的研究十分有限。运用静态箱采样、利用大气预浓缩仪-GC-MS研究了鼎湖山两种典型森林——马尾松林（Pine forest, PF）和季风常绿阔叶林（Monsoon evergreen broadleaf forest, BF）土壤BTEX通量对模拟氮沉降增加的响应。结果表明：自然氮沉降条件下，PF土壤吸收BTEX，乙苯吸收速率最大(-51.52±10.94) pmol·m-2·s-1，低氮抑制了PF土壤对BTEX的吸收，中氮主要使土壤由“汇”变为“源”；BF土壤释放BTEX，甲苯释放速率最高(7.11±0.12) pmol·m-2·s-1，施氮降低了BF土壤BTEX释放量或使土壤由“源”变“汇”，且低氮和高氮的影响效果更显著。施氮条件下，PF 土壤甲苯与乙苯、间/对二甲苯、邻二甲苯通量显著相关，BF土壤苯与甲苯、间/对二甲苯、邻二甲苯显著相关。土壤BTEX通量无明显日变化规律，对照和高氮样地最大释放均出现在7：00，最大吸收出现在19：00（对照样地）和13：00（高氮样地）。自然氮沉降条件下，BF土壤CO2通量(29.46±3.27) mg·m-2·h-1显著高于PF土壤(11.02±0.96) mg·m-2·h-1，两个水平氮处理均促进了两种林型土壤CO2的释放。土壤BTEX通量与土壤温度、大气温度和CO2浓度无显著相关性；邻二甲苯和乙苯通量与土壤湿度呈显著相关。
분계물（BTEX）시일류중요적휘발성유궤화합물（VOCs），능삼여대기광화학반응，병대인체건강유중요영향。토양능석방혹흡수BTEX，담침강회영향토양생태과정，종이가능영향토양BTEX통량。유관삼림토양BTEX통량대담침강향응적연구십분유한。운용정태상채양、이용대기예농축의-GC-MS연구료정호산량충전형삼림——마미송림（Pine forest, PF）화계풍상록활협림（Monsoon evergreen broadleaf forest, BF）토양BTEX통량대모의담침강증가적향응。결과표명：자연담침강조건하，PF토양흡수BTEX，을분흡수속솔최대(-51.52±10.94) pmol·m-2·s-1，저담억제료PF토양대BTEX적흡수，중담주요사토양유“회”변위“원”；BF토양석방BTEX，갑분석방속솔최고(7.11±0.12) pmol·m-2·s-1，시담강저료BF토양BTEX석방량혹사토양유“원”변“회”，차저담화고담적영향효과경현저。시담조건하，PF 토양갑분여을분、간/대이갑분、린이갑분통량현저상관，BF토양분여갑분、간/대이갑분、린이갑분현저상관。토양BTEX통량무명현일변화규률，대조화고담양지최대석방균출현재7：00，최대흡수출현재19：00（대조양지）화13：00（고담양지）。자연담침강조건하，BF토양CO2통량(29.46±3.27) mg·m-2·h-1현저고우PF토양(11.02±0.96) mg·m-2·h-1，량개수평담처리균촉진료량충림형토양CO2적석방。토양BTEX통량여토양온도、대기온도화CO2농도무현저상관성；린이갑분화을분통량여토양습도정현저상관。
BTEX are known as a type of volatile organic compounds (VOCs), which involve in atmospheric photochemical process and pose threats to human health and environment. Soil can act as both source and sink for BTEX. Increasing nitrogen deposition may influence soil ecological processes leading to changes in soil BTEX fluxes. Although nitrogen deposition has received much attention, the research on soil BTEX fluxes impacted by nitrogen deposition is still scarce. In this study, employing the static-chamber coupled with preconcentrator-GC-MS techniques, the responses of soil BTEX fluxes to simulated elevated nitrogen deposition were studied in two dominated forests, namely, pine forest (PF) and monsoon evergreen broadleaf forest (BF) in Dinghushan. The results showed that PF soil acted as sink for BTEX in the controlled sites, with the maximum uptake rate of (-51.52±10.94) pmol·m-2·s-1 for ethyl benzene. BTEX uptake rates decreased with low nitrogen additions and the soil function changed from “sink” to “source” with medium nitrogen additions in PF. In BF, meanwhile, soil acted as source for BTEX in controlled sites, with the maximum emission rate of (7.11±0.12) pmol·m-2·s-1for toluene. BTEX emission rates decreased, or the soil changed the function from “source” to “sink” after the nitrogen additions in BF, with the significant difference in low and high nitrogen addition sites from those in controlled sites. In addition, significantly high correlation coefficients were observed between toluene and ethyl benzene, xylene in PF soil as well as between benzene and toluene, xylene in BF soil with nitrogen treated. On the basis of measurements every 3 h each day for controlled and high nitrogen addition sites in BF, no clear diurnal variations were found for BTEX fluxes. The highest emission rates appeared at 7:00 in both sites and the highest uptake rates appeared at 19:00 and 13:00 in the controlled site and high nitrogen addition site, respectively. Soil CO2 emission rates (29.46±3.27) mg·m-2·h-1 in BF were significantly higher than those in PF in controlled sites (11.02±0.96) mg·m-2·h-1, and the rates in all the nitrogen addition sites increased compared with those in the controlled sites in both forests. Soil BTEX fluxes showed no significant correlation with soil temperature, air temperature or CO2 emission rates, but o-xylene and ethyl benzene fluxes showed significant correlation with soil water content.