不同原理分析仪观测大气中氮氧化物对比研究

氮氧化物(NOx)是大气二次光化学污染臭氧的重要前体物,但目前对其总量和分量的测量仍存在着一些难以解决的问题。选择3种不同原理的市售氮氧化物分析仪在广东和北京进行比对观测实验,从而比较其各自的优缺点及适用性。结果表明,钼转化法(MC)测得的NOx比光转化法(LC)及液相化学发光法(LPC)所测得的值都明显偏高,可近似认为是NOy。LPC检测NO2时受到PAN等含有—NO2生色基团的干扰,结果比LC略高。LC测得的NOx值与实际大气最为接近。MC测定的NOx比实际值高,但能满足空气质量指标监测的需求;LC能够准确测定大气中的NOx,但造价太高,仅适用于大气化学机理研究;而LPC原理的仪器适合于短时间的航测、高塔和系留艇进行垂直梯度观测。

A comparison research on observation of ambient NOx by different principle analyzers

Nitrogen oxides (NO_x) is one of important precursors of ozone (O_3), which is the most wellknown secondary air pollutant produced from photochemical reactions. At present, some difficulties about accurately measuring the components and total amount of NO_x are still existed. Three nitrogen-oxide analyzers with different principles were conducted in Guangdong and Beijing station respectively to compare their advantage,disadvantage and applicability. The results showed that the value of NO_x measured by the method of MO converter (MC) was much higher than that of light eonverter (LC) and liquid-phase chemiluminescence (LPC), which can be approximately thought as NO_y. LPC was interfered by the PAN and materials containing chromogenie radical-NO_2, so the result of which was slightly higher than that of LC. Compared to the other two methods, the value measured by LC was mostly closed to the actual value of NO_x in atmosphere. Although the value of NO_x measured by MC was higher than the real concentration, it still could conform to the requirement of monitoring air quality indexes. The method of LC could accurately measure ambient NO_x, but due to its high price, it was mainly applied on studying the mechanism of atmospheric chemistry. And the LPC analyzer is appropriate to measure NO_x at short time in aerial, tower and tethered airship for vertical observation.