A New PM Sampler with a Built-In Black Carbon Continuous Monitor

Abstract

We introduce a new instrument for sampling the airborne particulate matter (PM) while monitoring the black carbon (BC) atmospheric concentration. The concentration of PM and BC are usually measured by separate instruments with possible systematics differences even in the collecting inlets. The new equipment is based on a low-volume sequential PM sampler, fully compliant with the EU-CEN and US-EPA regulatory standards, with a built-in optical BC monitor. The BC concentration is continuously measured during the sampling in the PM accumulated on the filter while the PM concentration can be obtained off-line by a standard gravimetric analysis. The optical set-up, upstream the collecting filter, is composed by a single wavelength light source (λ = 635 nm) and a photodiode, placed in way to receive the light backscattered by the filter surface at a fixed angle. The mechanical arrangement does not introduce any perturbation to the PM sampling. Thanks to an original calibration curve, the sample absorbance is deduced from the output signal of the photodiode. Finally, the BC concentration is obtained through the Mass Absorption Coefficient (MAC). After the sampling and the PM gravimetric determination, the same filter can be sent to other compositional analyses. Thermo-optical quantification of the Elemental and Organic Carbon (EC and OC) in the filter sample can thus be exploited to tune the MAC value to the PM composition of a particular site. The main features of the new instrument and the set of validation tests against other PM samplers and BC monitors of widespread use (i.e.,: Multi Angle Absorption Photometer and aethalometer) are detailed and discussed.

Atomic spectrometry update – a review of advances in environmental analysis

“…The "CC-TRAIRER" (Climate Change-TRailer for AIR and Environmental Research) system 13 was a small towed-caravan with OPCs for PM 1 , PM 2.5 , PM 4 and PM 10 measurements, NO x and O 3 gas analysers and a lter sampler for gravimetric and chemical analysis. Information on power requirements, cabin climate control and data transmission systems were summarised and a useful tabulation given of mobile laboratory equipment used in 16 other air monitoring studies. The sampling of emissions from cooling towers is challenging due to concerns over accessibility and working at heights.…”

“…Systems that utilised either a particle-into-liquid sampler (two variants examined) or a mist chamber sampler coupled to an absorption spectrometer were evaluated 15 for use on-board a survey aeroplane. A new instrument developed for ground-based black carbon measurements consisted 16 of a CEN-compliant PM-filter-based sampler (with either a PM 2.5 or PM 10 inlet) together with an integral optical module that enabled passing particles to be monitored prior to their deposition on a filter. The analysis of filter samples in the laboratory for EC and OC enabled calculation of a MAC value for each specific sampling location so that the black carbon absorbance measurements at 635 nm could be converted to the equivalent mass concentrations.…”