TY - JOUR

T1 - Further development of a new flow-through directional passive air sampler for monitoring ambient nitrogen dioxide

AU - Lin, Chun

AU - Timmis, Roger

AU - Jones, Kevin C.

PY - 2010/3/19

Y1 - 2010/3/19

N2 - We have previously introduced a new type of rotatable flow-through directional passive air sampler (DPAS) for monitoring trace air pollutants in ambient air. In wind tunnel tests, the sampler turns into the prevailing wind direction and retains NO2 (used as a test pollutant) on an internal sampling medium ring of triethanolamine (TEA)-coated meshes to indicate the source of pollution. However, these meshes can become saturated, after exposure times of tens of hours or a few days, due to the relatively small masses of TEA which can be coated onto them. This paper outlines the saturation problem and presents a possible redesign of the DPAS sampling approach, to allow longer-term (weeks-months) deployments, where air passes over larger volumes of TEA retained in a compartmentalised carousel. Investigations varying the volume, depth and mixing of TEA in sampling compartments suggested that the limiting step of NO2 uptake was its rate of supply from the atmosphere. In wind tunnel trials, NO2 uptake into TEA continued linearly in response to a stable air concentration over periods of tens of days, showing no signs of saturation. Uptake was wind velocity dependent across the range of 0.50, 2.00, 5.00 and 8.00 m s-1. Results indicate that the total sampling time and storage capacity of the TEA for NO2 can be varied to meet deployment time requirements, indicating that long-term, cheap, directional passive air sampling is achievable.

AB - We have previously introduced a new type of rotatable flow-through directional passive air sampler (DPAS) for monitoring trace air pollutants in ambient air. In wind tunnel tests, the sampler turns into the prevailing wind direction and retains NO2 (used as a test pollutant) on an internal sampling medium ring of triethanolamine (TEA)-coated meshes to indicate the source of pollution. However, these meshes can become saturated, after exposure times of tens of hours or a few days, due to the relatively small masses of TEA which can be coated onto them. This paper outlines the saturation problem and presents a possible redesign of the DPAS sampling approach, to allow longer-term (weeks-months) deployments, where air passes over larger volumes of TEA retained in a compartmentalised carousel. Investigations varying the volume, depth and mixing of TEA in sampling compartments suggested that the limiting step of NO2 uptake was its rate of supply from the atmosphere. In wind tunnel trials, NO2 uptake into TEA continued linearly in response to a stable air concentration over periods of tens of days, showing no signs of saturation. Uptake was wind velocity dependent across the range of 0.50, 2.00, 5.00 and 8.00 m s-1. Results indicate that the total sampling time and storage capacity of the TEA for NO2 can be varied to meet deployment time requirements, indicating that long-term, cheap, directional passive air sampling is achievable.

U2 - 10.1039/b916496k

DO - 10.1039/b916496k

M3 - Journal article

C2 - 20445851

AN - SCOPUS:77949398787

VL - 12

SP - 635

EP - 641

JO - Journal of Environmental Monitoring

JF - Journal of Environmental Monitoring

SN - 1464-0325

IS - 3

ER -