5 Sources of PM10 in New Zealand
The results of the emission inventory investigations into sources of particles in New Zealand are shown in Figure 5.1. With the exception of Bay of Plenty, Taranaki and Gisborne, these data represent average wintertime emission sources. The main limitation with the assessment is the exclusion of sea spray emissions, as these may be a significant contributor in some of the coastal locations. Variations in the inclusion of some of the smaller emission sources are unlikely to significantly impact on results as all inventories include an assessment of the main anthropogenic contributors, domestic fires, motor vehicles and industrial emissions.
In Figure 5.1, results are presented for the main urban areas within the different regions. For areas such as Canterbury and Otago results are also available for many of the smaller urban towns (see Sections 2.6 and 2.8 and Table 5.1). In these smaller areas domestic fires are generally more dominant than for the larger cities of Christchurch and Dunedin. In contrast, results for some of the smaller north island areas (e.g. Tokoroa and Taupo), show a stronger industry component.
Table 5.1 shows estimates of PM10 and TSP discharges to air from different sources in kilograms per day and tonnes for per year. For the larger cities, PM10 emissions of around four to 30 tonnes per day are estimated, compared to around one tonne or less for most of the smaller urban areas. In Auckland, just less than 19 tonnes of PM10 is estimated from domestic heating per day compared to around eight tonnes for Christchurch and six tonnes for Wellington.
The relative contributions to PM10 emissions illustrated in Figure 5.1 and Table 5.1 are based on assumptions relating to emission rates and fuel use and contain some degree of uncertainty. There is some variation from area to area in the approach taken and the subsequent confidence in the results. The potential contribution of sea spray combined with concerns regarding methodological issues suggests that estimates of the relative contribution for Auckland illustrated in Figure 5.1 may not be appropriate.
The main source of particles within the urban areas of New Zealand is solid fuel burning for domestic home heating. However, industrial emissions also have the potential to be a significant contributor in a number of locations.
Table 5.1: Comparison of emissions estimates for different regions of New Zealand
View comparison of emissions estimates for different regions of New Zealand (large table)
