6 Methods

6.1 Quality assurance

All monitoring services are undertaken by Watercare Services Ltd in accordance with the Ministry for the Environment’s Good Practice Guide for Air Quality Monitoring and Data Management and wherever applicable the appropriate Australian/New Zealand and US EPA monitoring methods.

Watercare Laboratory Services is accredited by International Accreditation New Zealand (IANZ) for the following methods:

  • AS 3580.7.1-1992 ‘Method 7.1: Determination of carbon monoxide – direct-reading instrumental method’
  • AS 3580.5.1-1993 ‘Method 5.1: Determination of oxides of nitrogen – chemiluminescence method’
  • AS 3580.4.1-2008 ‘Method 4.1: Determination of sulphur dioxide – direct reading instrumental method’
  • AS/NZS 3580.9.3-2003 ‘Method 9.3: Determination of ambient particulates (gravimetric method) – TSP high volume sampling’
  • AS/NZS 3580.9.6-2003 ‘Method 9.6: Determination of ambient particulates (gravimetric method) – PM10 high volume sampling’
  • AS 3580.9.11 – 2008 ‘Method 9.11: Determination of suspended particulate matter – PM10 beta attenuation monitors’
  • APHA Method 3030 for the lead digest
  • US EPA Method 200.8 (modified) for lead analysis by ICPMS.

As part of the GEMS/AMIS programme, Watercare Laboratory Services provides the following monitoring services:

  • Instrument operation, calibration and maintenance. This includes the use of automatic daily calibration systems for all continuous ambient gas monitors ensuring that the requirements of the relevant Australian Standards for weekly calibration of continuous analysers are met.
  • Site maintenance as well as commissioning new sites and decommissioning old sites, when necessary.
  • Data logging, polling, checking, re-scaling, validation, ratification and reporting. This encompasses the entire data quality assurance process ensuring that the final data set reported is fit for the purpose of the GEMS/AMIS programme.

6.2 Analytical methods

6.2.1 Carbon monoxide

Measurements are made in accordance with AS 3580.7.1-1992 ‘Determination of Carbon Monoxide – Direct Reading Instrumental Method’. The performance of the instrument is checked using an automatic calibration system ensuring compliance with the method which requires instrumentation to be calibrated on a weekly basis.

The instrument itself is an infrared absorption gas analyser which continuously measures carbon monoxide. This allows data to be analysed and reported over a variety of average periods, including 10-minute, 24-hour and one year.

6.2.2 Nitrogen oxides

Measurements are made in accordance with AS 3580.5.1-1993 ‘Determination of Oxides of Nitrogen – Chemiluminescence Method’. The performance of the instrument is checked using an automatic calibration system ensuring compliance with the method which requires instrumentation to be calibrated on a weekly basis.

The instruments themselves are chemiluminescence gas analysers which continuously measure nitrogen oxides. This allows data to be analysed and reported over a variety of average periods, including 10-minute, 24-hour and one year.

6.2.3 Sulphur dioxide

Measurements are made in accordance with AS 3580.4.1-2008 ‘Determination of Sulphur Dioxide – Direct Reading Instrumental Method’. The performance of the instrument is checked using an automatic calibration system ensuring compliance with the method which requires instrumentation to be calibrated on a weekly basis.

The instruments themselves are UV fluorescence gas analysers which continuously measure sulphur dioxide. This allows data to be analysed and reported over a variety of average periods, including 10-minute, 24-hour and one year.

6.2.4 Volatile organic compounds (VOCs)

VOCs are measured using passive 3M organic vapour monitor badges, which are exposed for three-month periods (January–March, April–June, July–September and October–December). The VOCs diffuse on to the badges, which are coated with activated carbon. Following exposure, the samples are forwarded to AsureQuality who extract the VOCs using carbon disulfide and analyse them using gas chromatography-mass spectrometry (GC-MS). AsureQuality is IANZ accredited for VOCs by GC-MS using National Institute for Occupational Safety and Health (NIOSH) Method 1500.

The subsequent results are calculated in accordance with the manufacturer’s instructions (3M Technical Data Bulletin 1028) allowing results to be converted to standard temperature (0°C) and pressure (1 bar).

Note: Investigations have determined that samples of 1,3-butadiene are unstable when held above -4.41°C with significant reverse desorption occurring. Due to the potential for error over a three-month exposure period, 1,3-butadiene has not been analysed and reported. Alternative methods of measuring 1,3-butadiene are OSHA Method 56 and NIOSH Method 1024 both of these involve the use of solid sorbent coconut charcoal tubes.

6.2.5 Particulate matter as PM10

Measurements are made in accordance with AS 3580.9.11–2008 ‘Determination of suspended particulate matter – PM10 beta attenuation monitors’ (BAM). The instrument is fitted with a size-selective PM10 head with an inlet temperature of 40°C. The BAM continuously measures the intensity of beta particles passing through a filter tape. This allows PM10 data to be analysed and reported over a variety of average periods, including 10-minute, 24-hour and one year.

6.2.6 Total suspended particulate matter (TSP)

TSP monitoring is in accordance with Watercare’s Air Quality Group Test Method T101. The method was based on Australian Standard 2724.2 – 1987 and British Standard 1747 and was developed by the Ministry of Health (MoH). It is a gravimetric method of measuring particulates and is modelled on the system for high volume sampling as described in AS/NZS 3580.9.3-2003.

The equipment used to collect TSP involves ambient air being pulled through a 55 mm glass fibre filter by a vacuum pump. A gas meter is attached and is used to measure the air volume (m³) drawn through the filter. The filter is held in a cassette and is covered with a rain shelter at 3.5 m above ground. Pre-weighed filters are collected and sampled on a weekly or seven-day cycle every Thursday.

This method is different to that recommended in the Ministry for the Environment’s Good Practice Guide for Air Quality Monitoring and Data Management 2009. The method has been used to measure TSP since 1964 and the results will vary when compared to more modern techniques.

6.2.7 Lead

Lead is sampled during the winter months, June–August, using the same samples acquired to measure TSP. Analysis of lead is performed by Watercare Laboratory Services according to APHA Method 3030 and US EPA Method 200.8 modified. This involves analysing each individual TSP filter exposed during the winter period using mixed acid digestion. This sample is then analysed for lead using ICP-MS. The concentration of lead is then determined from the amount of lead detected and the total volume of air sampled during that sample period. Concentrations are averaged for the three-month monitoring period.

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