Eddy covariance fluxes of peroxyacetyl nitrates (PANs) and NOy to a coniferous forest -: art. no. D09304
Eddy covariance fluxes of peroxyacetyl nitrates (PANs) and NOy to a coniferous forest -: art. no. D09304
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DOI：
10.1029/2005jd006631
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发表时间：
2006-05-06
影响因子：
4.4
通讯作者：
Guenther, A
中科院分区：
文献类型：
--
作者：
Turnipseed, AA;Huey, LG;Guenther, A
[1]我们采用快速响应热解离化学电离质谱仪（TD-CIMS）系统来测量过氧乙酰硝酸盐（PAN）、过氧丙酰硝酸盐（PPN）和过氧甲基丙烯酰硝酸盐（MPAN）的涡度协方差通量。 2003 年 7 月，在北卡罗来纳州的火炬松林中连续八天测量了通量以及涡流协方差 NOy 通量。 PAN 浓度和垂直风速之间的协方差表明沉积通量一致，范围约为 - 14 ng N m(-2) s(-1)。平均日间通量峰值为 - 6.0 ng N m(-2) s(-1)，约占日间 NOy 通量的 20%。计算表明 PAN 的最小白天表面电阻在 70 - 130 s m(-1) 范围内。据估计，白天大约一半的吸收是通过植物气孔进行的。平均 PAN 沉积速度 V-d(PAN) 显示白天最大值类似于 10.0 mm s(-1)；然而，夜间沉积并未停止。 V-d(PAN) 在夜间变化很大，当冠层因降水或露水形成而潮湿时，V-d(PAN) 会增加。 MPAN 和 PPN 的沉积速度 Diel 模式与 PAN 相似。这些结果表明，PAN 的沉积（至少在针叶林冠层上）比当前沉积算法预测的要快得多。尽管在温暖的夏季，PAN 的沉积不太可能与热分解竞争，但在寒冷地区或冬季，它可能在从大气中去除 PAN 方面发挥重要作用。 PAN 在植物表面和内部的命运仍然未知，但可能为生态系统提供了以前被忽视的氮源。
[ 1] We employed a fast response thermal dissociation-chemical ionization mass spectrometer (TD-CIMS) system to measure eddy covariance fluxes of peroxyacetyl nitrate ( PAN), peroxypropionyl nitrate (PPN) and peroxymethacryloyl nitrate (MPAN). Fluxes were measured for eight consecutive days in July 2003 at a Loblolly pine forest in North Carolina along with eddy covariance NOy fluxes. Covariances between PAN concentration and vertical wind velocity indicated consistent deposition fluxes that ranged up to approximately - 14 ng N m(-2) s(-1). The average daytime flux peaked at - 6.0 ng N m(-2) s(-1) and accounted for similar to 20% of the daytime NOy flux. Calculations suggest minimum daytime surface resistances for PAN in the range of 70 - 130 s m(-1). It was estimated that approximately half of daytime uptake was through plant stomates. Average PAN deposition velocities, V-d(PAN), showed a daytime maximum of similar to 10.0 mm s(-1); however, deposition did not cease during nighttime periods. V-d(PAN) was highly variable at night and increased when canopy elements were wet from either precipitation or dew formation. Diel patterns of deposition velocity of MPAN and PPN were similar to that of PAN. These results suggest that deposition of PAN, at least to coniferous forest canopies, is much faster than predicted with current deposition algorithms. Although deposition of PAN is unlikely to compete with thermal dissociation during warm summer periods, it will likely play an important role in removing PAN from the atmosphere in colder regions or during winter. The fate of PAN at the surface and within the plants remains unknown, but may present a previously ignored source of nitrogen to ecosystems.