Nitrate postdeposition processes in Svalbard surface snow
Nitrate postdeposition processes in Svalbard surface snow
复制标题
DOI：
10.1002/2013jd021234
复制
发表时间：
2014-11
期刊：
影响因子：
--
通讯作者：
M. Björkman;C. Vega;R. Kühnel;F. Spataro;A. Ianniello;G. Esposito;J. Kaiser;A. Marca;A. Hodson;E. Isaksson;T. Roberts
中科院分区：
文献类型：
--
作者：
M. Björkman;C. Vega;R. Kühnel;F. Spataro;A. Ianniello;G. Esposito;J. Kaiser;A. Marca;A. Hodson;E. Isaksson;T. Roberts
积雪作为大气活性氮的汇，但几个postdeposition途径已被报道改变雪硝酸盐的浓度和同位素组成与大气边界层化学的影响，冰芯记录，和陆地生态学雪融化。在斯瓦尔巴德群岛的新勒松附近，在冬季（2010年2月11日至15日）和春季（2010年4月9日至5月5日），每天对地表积雪进行仔细采样，揭示了积雪中复杂的过程模式。研究发现，干沉降在沉降后的损失中占主导地位，对于均匀的地表雪，硝酸盐的净沉降速率为（0.6 ± 0.2）µmol m−2 d−1。在纽约州，这种表面干沉积可能仅仅是由于氧化态氮的远距离大气传输，也可能包括来自较深雪层的光解/细菌排放物的再沉积。我们的数据进一步证实，极地盆地空气质量将15 N贫化的硝酸盐带到斯瓦尔巴特群岛，而高硝酸盐δ（18 O）值仅发生在臭氧贫化的空气中，并表明这些特征反映在沉积的硝酸盐中。这种臭氧耗尽的空气是由于平流到现场的空气团中的活性卤素化学。然而，在高BrO（低臭氧）事件期间，纽约州的地面雪被证明在该地区的卤素动力学中发挥了积极作用，如溴化物浓度下降和硝酸盐δ（18 O）增加所示。数据还表明，积雪BrO-NOx循环在事件后时期继续，当环境臭氧和BrO水平恢复时。
The snowpack acts as a sink for atmospheric reactive nitrogen, but several postdeposition pathways have been reported to alter the concentration and isotopic composition of snow nitrate with implications for atmospheric boundary layer chemistry, ice core records, and terrestrial ecology following snow melt. Careful daily sampling of surface snow during winter (11–15 February 2010) and springtime (9 April to 5 May 2010) near Ny‐Ålesund, Svalbard reveals a complex pattern of processes within the snowpack. Dry deposition was found to dominate over postdeposition losses, with a net nitrate deposition rate of (0.6 ± 0.2) µmol m−2 d−1 to homogeneous surface snow. At Ny‐Ålesund, such surface dry deposition can either solely result from long‐range atmospheric transport of oxidized nitrogen or include the redeposition of photolytic/bacterial emission originating from deeper snow layers. Our data further confirm that polar basin air masses bring 15N‐depleted nitrate to Svalbard, while high nitrate δ(18O) values only occur in connection with ozone‐depleted air, and show that these signatures are reflected in the deposited nitrate. Such ozone‐depleted air is attributed to active halogen chemistry in the air masses advected to the site. However, here the Ny‐Ålesund surface snow was shown to have an active role in the halogen dynamics for this region, as indicated by declining bromide concentrations and increasing nitrate δ(18O), during high BrO (low‐ozone) events. The data also indicate that the snowpack BrO‐NOx cycling continued in postevent periods, when ambient ozone and BrO levels recovered.