Centro de Estudios Ambientales de Cienfuegos (CEAC), AP 5. Ciudad Nuclear, CP 59350 Cienfuegos, Cuba; Laboratorio Integrado de Calidad Ambiental (LICA), Universidad de Navarra, C/Irunlarrea s/n, 31008, Navarra, Spain.
Laboratorio Integrado de Calidad Ambiental (LICA), Universidad de Navarra, C/Irunlarrea s/n, 31008, Navarra, Spain.
Sci Total Environ. 2018 Nov 15;642:723-732. doi: 10.1016/j.scitotenv.2018.06.106. Epub 2018 Jun 15.
The constant increase of anthropogenic emissions of aerosols, usually resulting from a complex mixture from various sources, leads to a deterioration of the ambient air quality. The stable isotope compositions (δC and δN) of total carbon (TC) and nitrogen (TN) in both PM and emissions from potential sources were investigated for first time in a rural and an urban Caribbean costal sites in Cuba to better constrain the origin of the contamination. Emissions from road traffic, power plant and shipping emissions were discriminated by coupling their C and N contents and corresponding isotope signatures. Other sources (soil, road dust and cement plant), in contrast, presented large overlapping ranges for both C and N isotope compositions. δC isotope compositions in the rural (average of -25.4 ± 1.2‰) and urban (average of -24.8 ± 1.2‰) sites were interpreted as a mixture of contributions from two main contributors: i) fossil fuel combustion and ii) cement plant and quarries. Results also showed that this last source is impacting more air quality at the urban site. A strong influence from local wood burning was also identified at the rural site. These conclusions were comforted by a statistical analysis using a conditional bivariate probability function. TN and δN values from the urban site demonstrated that nitrogen in PM was generated by secondary processes through the formation of (NH)SO. The exchange in the (NH)SO molecule between gaseous NH and particle NH under stoichiometric equilibrium may control the observed N enrichment. At low nitrogen concentrations in the aerosols, representing PM with both the highest primary N and lowest secondary N proportions, comparison with the δN of potential sources indicate that emissions from diesel car and power plant emissions may represent the major vectors of primary nitrogen.
人为气溶胶排放物的持续增加通常是由各种来源的复杂混合物造成的，这导致了环境空气质量的恶化。本研究首次在古巴的一个农村和一个城市沿海地区的 PM 和潜在来源排放物中调查了总碳（TC）和氮（TN）的稳定同位素组成（δC 和 δN），以更好地约束污染的来源。通过耦合它们的 C 和 N 含量及其相应的同位素特征，区分了道路交通、电厂和航运排放的污染源。相比之下，其他来源（土壤、道路灰尘和水泥厂）的 C 和 N 同位素组成有很大的重叠范围。农村（平均为-25.4±1.2‰）和城市（平均为-24.8±1.2‰）站点的 δC 同位素组成被解释为两种主要来源贡献的混合物：i）化石燃料燃烧和 ii）水泥厂和采石场。结果还表明，最后一个来源对城市站点的空气质量影响更大。在农村站点还发现了当地木柴燃烧的强烈影响。使用条件二元概率函数的统计分析进一步证实了这些结论。城市站点的 TN 和 δN 值表明，PM 中的氮是通过二次过程通过（NH）SO 的形成产生的。在化学计量平衡下，气态 NH 和颗粒 NH 之间的（NH）SO 分子交换可能控制了观察到的 N 富集。在气溶胶中氮浓度较低的情况下，代表具有最高原始 N 和最低二次 N 比例的 PM，与潜在来源的 δN 比较表明，柴油车和电厂排放的排放物可能代表主要的原始氮源。
