Evolution of NOx levels measured by means of passive samplers at a mediterranean coastal area

15 November 2019

Delgado, J.M., Esteve, V.

Geophysical Research Abstracts, 2003, 5, 01971

The aim of this work is the study of the evolution of nitrogen oxides levels in a Mediterranean coastal area in the years 2001 and 2002 and stand relationships between NOx levels and ozone levels both measured with passive samplers. Concretely, the area studied is “La Plana de Castellón” and its surroundings in Castellón, Spain. In years 2001 and 2002 measurement campaigns have been made during summer, the higher photochemical activity period from July to September in order to obtain the necessary data of NOx levels to study the relationships with measured tropospheric ozone levels as well as to study the evolution of measured NOx levels along two years. Measuring campaigns have been divided into sampling periods of one week. Measurements have been made by means of a new lower-cost sampling technology: passive samplers. Radiello samplers (Cocheo et al, 1999) have been employed. The first year, 2001, twelve samples were collected each sampling period to cover an interest area of 1400 Km2. Two of these samples were laboratory blanks, four of them were situated at reference points (beside an automatic NOx sampler), one was situated at A7-E15 expressway, other at the main road N-340 and another one in a hard traffic road. The other three were placed in the main cities (Castellon and Benicassim). The second year, 2002, the interest area was enlarged a 30 per cent, raising 1830 km2. At 2002 year, sixteen samples were collected and some of them were situated in different locations to the previous year 2001. One of these samples was laboratory blank, five of them were situated at reference points (beside an automatic NOx sampler) with two co-located points, one sampler was situated at A7-E15 expressway, other two at the main road N-340 at different points and another one in a hard traffic road. Other two ones were placed in the main city (Castellon) and two ones were placed in the countryside. Samples located far from the main roads, at countryside show the lowest levels of NOx about 20 µg/m3, The highest levels of NOx are measured at the expressway, at roads and at the main city, Castellón, with levels up to 100 µg/m3 . The trend of evolution of NOx levels measured in years 2001 and 2002 is increasing. The value of the increase depends on the area measured varying form 3 per cent in areas not so far from roads, to 10 per cent in city areas. Nevertheless, in far inner areas (110 km far from the coast) where there is not much vehicle traffic, the trend of the evolution is decreasing about a 10 per cent from year 2001 to year 2002.