HONO, Particulate Nitrite, and Snow Nitrite at a Midlatitude Urban Site during Wintertime
HONO, Particulate Nitrite, and Snow Nitrite at a Midlatitude Urban Site during Wintertime
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DOI：
10.1021/acsearthspacechem.9b00023
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发表时间：
2019-05-01
影响因子：
3.4
通讯作者：
Pratt, Kerri A.
中科院分区：
文献类型：
--
作者：
Chen, Qianjie;Edebeli, Jacinta;Pratt, Kerri A.
亚硝酸（HONO）在冬季通过光解产生羟基自由基（OH）对大气的氧化能力起着重要作用。虽然我们知道HONO是从北极积雪中释放出来的，但在中纬度城市冬季环境中对HONO的稀疏观测阻碍了我们对冷季大气化学的理解。在这项研究中，2018年1月至2月期间，在密歇根州卡拉马祖市对环境HONO，颗粒亚硝酸盐（pN（III）; N（III）= NO2（aq）- + HONO（aq）+ H2ONO（aq）+）和雪亚硝酸盐（sN（III））进行了测量。在积雪覆盖的地面上观察到HONO和颗粒亚硝酸盐水平升高，这可能是由于积雪排放HONO以及大气边界层中的湍流混合较弱。在积雪覆盖的地面上，HONO的中午峰值为87 +/- 60（1 sigma）万亿分之一（ppt），这表明光化学积雪HONO的产生，可能部分通过积雪硝酸盐的光解，只有少量的贡献来自颗粒硝酸盐的光解。高浓度的雪亚硝酸盐（0.4 +/- 0.3（1西格玛）μ M）支持的假设，积雪是一个重要的来源HONO到大气中。平均而言，OH的生产率从HONO光解，在近地面大气（约2米以上），计算为约一个数量级高于O-3光解在积雪覆盖的地面。未来的研究需要量化HONO排放量从中纬度城市积雪，预期HONO生产由于高浓度的雪硝酸盐和亚硝酸盐的人为颗粒硝酸盐和亚硝酸盐沉积。
Nitrous acid (HONO) plays an important role in the oxidative capacity of the atmosphere during wintertime via photolysis to produce hydroxyl radicals (OH). While it is known that HONO is emitted from the Arctic snowpack, sparse observations of HONO in the midlatitude urban wintertime environment have hindered our understanding of cold-season atmospheric chemistry. In this study, measurements of ambient HONO, particulate nitrite (pN(III); N(III) = NO2(aq)- + HONO(aq) + H2ONO(aq)+), and snow nitrite (sN(III)) were conducted in Kalamazoo, Michigan during January-February 2018. Elevated levels of HONO and particulate nitrite were observed over snow-covered ground, likely due to emissions of HONO from the snowpack, as well as weak turbulent mixing in the atmospheric boundary layer. The noontime peak in HONO of 87 +/- 60 (1 sigma) parts per trillion (ppt) over snow-covered ground suggests photochemical snowpack HONO production, likely in part through snowpack nitrate photolysis, with only a minor contribution from particulate nitrate photolysis. High concentrations of snow nitrite (0.4 +/- 0.3 (1 sigma) mu M) support the hypothesis that the snowpack is a significant source of HONO to the atmosphere. On average, the OH production rate from HONO photolysis, in the near-surface atmosphere (approximate to 2 m above ground), was calculated to be about an order of magnitude higher than that from O-3 photolysis over snow-covered ground. Future studies are needed to quantify HONO emissions from the midlatitude urban snowpack, given expected HONO production due to high concentrations of snow nitrate and nitrite from anthropogenic particulate nitrate and nitrite deposition.