No part of the contents of the publication may be reproduced without the permission of this agency. The focus of Wagerup's 2009 air quality study was to investigate odor events associated with episodes of poor air quality occurring near the Alcoa Wagerup Refinery. VOCs detected by PTRMS are identified by association of the detected ionic mass-to-charge ratio (m/z) with VOCs known or expected to be present in the ambient air.
Concentrations of VOCs corresponding to m/z 33 (methanol) and m/z 59 (acetone) detected by PTRMS increased above background levels at the time of community complaints on June 3 and 12, 2009. Overall, for 64 per cent days when there were two or more community observations during the study period, there was an increase in the concentration of m/z 33 (methanol) and m/z 59 (acetone) detected by PTRMS between 6 :00:00 and 11:00:00:00, corresponding to the time of community complaints. If all samples taken during the study period are averaged, the phosphorus concentration is below the annual environmental guideline.
Analysis of the PM2.5 to PM10 ratio measured in Bunbury indicates that the source of elevated particulate levels on 16 May 2009 is likely to be from wood smoke possibly caused by bushfires or controlled burns in the area. There are a number of sources of compounds measured during this study, including wood smoke, vehicles, vegetation, and the Alcoa Wagerup refinery; with evidence of each of these sources contributing data.
Introduction
Monitoring sites
Overview of measurement program and analysis
DEC air quality monitoring stations
Air quality parameters
- Particles
- Nitrogen dioxide (NO 2 )
- Sulfur dioxide (SO 2 )
- Carbon monoxide (CO)
- VOCs measured by Proton Transfer Reaction Mass Spectrometer (PTRMS)
- Heavy metals
- Intensive observation periods (IOPs)
- Community sampling program
Most anthropogenic emissions to air are in the form of nitric oxide (NO), which can be converted to NO2. It is produced in the burning of coal and oil, and in the smelting of metal sulphide ores. CO is a refinery emission (NPI 2009) and can also form in the atmosphere from the oxidation of methane.
VOCs measured by Proton Transfer Reaction Mass Spectrometer (PTRMS) A highly sensitive PTRMS (Ionicon Analytik, Innsbruck, Austria) was installed in Yarloop to A highly sensitive PTRMS (Ionicon Analytik, Innsbruck, Austria) was installed in Yarloop to continuously measure volatile organic compounds monitor in ambient air from May 1, 2009 to October 2, 2009. These VOCs can be identified by other discontinuous analysis techniques, such as those listed in the. DEC employees were deployed in the field for IOPs to assess refinery odors and take canister samples.
DEC employees took measurements and conducted odor surveys as part of the IOPs on July 14 and 29, 2009 and October 2, 2009. Many of the buses taken by the community were analyzed by the PTRMS at Yarloop.
Results
- Continuous PTRMS data and community observations
- Continuous PTRMS data and community observations — 3 June
- Continuous PTRMS data and community observations— 12 June
- General trend for VOCs measured continuously by PTRMS with complaints data
- IOPs and canister samples analysed via PTRMS
- PTRMS ancillary measurements
- Heavy metals
- Particles as PM 2.5
- Nitrogen dioxide (NO 2 )
- Carbon monoxide (CO)
- Sulfur dioxide (SO 2 )
It is clear from Figure 4.3.1 that there is horizontal variability in the winds used to calculate the return trajectories of the different monitoring stations, but as a general trend it is clear that the air sampled at the Yarloop monitoring station at the time complaints were traveling about the refinery area before reaching Yarloop. The mean concentration ratio of acetone to acetaldehyde on June 12, 2009 for the period from 7:40 a.m. to 10:50 a.m. (corresponding to three of four complaints) is 5.1, indicating that the refinery is a likely source of the broad peak of acetone and methanol detected in the morning. This increase in concentration (from about 5 ppb to 8 ppb above background) is evidenced by a broad spike in the PTRMS data indicating that these events develop over a time period of hours.
DEC staff were in the field taking measurements and conducting odor surveys as part of IOPs on July 14 and 29, 2009, and October 2, 2009. Many of these compounds (preliminarily identified in PTRMS measurements) are malodorous and were present at very low concentrations (i.e. in the low ppb range) The highest concentrations of VOCs detected by PTRMS in DEC IOP canisters obtained when a refinery odor (described as wet cement or caustic) was present, correspond to m/z 33 (methanol), m/z 59 (acetone), m/z 61 (acetic acid, multiple compounds), m/z 43 (multiple compounds including isopropanol), m/z 45 (acetaldehyde), m/z 93 (toluene) m/z 47 (ethanol, formic acid and numerous compounds) and m/z 107 (xylenes, benzaldehydes and numerous compounds). Galbally et al (2008) have previously observed sources of m/z 59 (acetone), m/z 45 (acetaldehyde), m/z 33 (methanol) and m/z 43 (multiple compounds) as well as NOx in the direction of the Wagerup refinery, which is consistent with known refinery emissions.
Many of the VOCs (masses) detected in the containers taken by DEC staff as part of the IOPs when a wet cement odor was present and by community members were also present in background containers. The PTRMS detected more compounds from cans taken when a wood smoke odor was present than in the containers taken when a wet cement odor was present. The masses detected in the DEC IOP wet cement and community samples were also detected in the wood smoke canisters.
All VOCs detected in other canisters analyzed by the USEPA TO-15 method (Table 4.5.1) were also detected in the canister collected on June 14, 2009. One-minute mean concentrations of VOCs detected in canisters of analyzed by the USEPA TO- 15 method are all below the respective 24-hour or annual MIL with the exception of one canister taken on June 14, 2009. Adsorbent tube and canister samples taken concurrently with the PTRMS measurements confirm that the VOCs of detected by PTRMS were in the low ppb range.
Yellow crosses represent heavy metal concentrations measured in the Perth Background Air Quality Study at a site in the Perth CBD and are included for comparison with levels measured at Bancell Road. Heavy metal concentrations (24-hour average) measured in the Perth CBD as part of the DEC Background Air Quality Study have been included in Figure 4.7.1 for reference. Due to the different averaging times, caution is needed when comparing concentrations measured in Perth CBD with those measured at Bancell Road, but the average concentrations (32 samples) of all heavy metals measured at Bancell Road are lower (often by an order of magnitude) than the average concentrations of those measured in the Perth CBD as part of the Perth Background Air Quality Study.
The red line indicates the NEPM PM2.5 advisory reporting standard of 25 µg/m3. The 24-hour average PM2.5 concentrations measured in Yarloop and Cookernup were below the advisory reporting standard of 25 µg/m3 for most of the study period. Analysis of the ratio of PM2.5 to PM10 measured in Bunbury suggests that the source is wood smoke, likely from forest fires or controlled burns in the area.
Conclusions
As part of the results of the Wagerup 2006 study, DEC identified August 27, 2006 as a day of significant refinery impacts on the surrounding area. Descriptions of the incident included: 'worst smell detected in a long time', 'rated smell as 6/6' and 'worst pollution incident in years'. From From 09:00 onwards, refinery odor was detected over a wide area south of the refinery as the layer of emissions mixed to ground level under post-stable conditions with low convective mixing.
Further information is available in the report 'Winter 2006 Study: Intensive air quality investigations at Wagerup, DEC 2008.'. As part of the Wagerup 2006 air quality measurements, CSIRO was contracted by Alcoa to undertake an air quality monitoring study using PTRMS. The CSIRO PTRMS was located at Boundary Road, south of the Wagerup refinery and measurements were undertaken from 10 August to 7 October 2006.
The results of the CSIRO study are available in the report 'Wagerup Winter 2006 VOC Study, Western Australia, CSIRO 2008' PTRMS data obtained as part of the CSIRO PTRMS 2006 study was provided to DEC in October 2008 by Alcoa. Figure 1 shows that the concentration of VOCs corresponding to the masses (i.e. compounds with mass to charge ratios m/z 33 and 59) detected by the CSIRO PTRMS on 27 August 2006 increases significantly (4–6 ppb above). background levels) at the time when most community complaints were received. There is a gap in ambient measurements from 8:45 to 9:15 due to the PTRMS measuring zero air at this time, but the concentration of acetone and methanol begins to increase before the zero air sequence begins at 8:45 and the peak in concentration is evident at 9:24 a.m. after completing the zero air sequence.
This increase in acetone and methanol concentrations detected by the CSIRO PTRMS on 27 August 2006 corresponding to the time of community complaints is consistent with PTRMS DEC 2009 results obtained from the times when odor complaints were received by the community (e.g. 3 June and 12 June 2009). This provides further evidence that methanol and acetone detected by PTRMS, in combination with other air quality measurements or community reports of odor can be used as indicators of the refinery plume. When comparing the guideline values in Appendix 3 with the results from the boxes analyzed by the USEPA TO-15 method, it should be noted that the results given in this study were compiled using different averaging periods.
Adsorbent Tubes Adsorbent tubes are commonly used collection media for sampling gases in air. Air Toxic A pollutant selected for assessment and included in Schedule 1 of the National Environment Protection (Air Toxics) Measure. Mass The term mass is used in this report to represent the protonated mass of the compound (ion) detected by the PTRMS in atomic mass units (amu).
MIL Monitoring Investigation Level - The concentration of an air toxicant which if exceeded requires an appropriate form of further investigation and evaluation. Odor Threshold The lowest concentration at which an odor is detected by 50 percent of the population.
