mercury which could be targeted for control measures. It is useful as an initial exercise but UNEP could provide more guidance on the appropriate input factors rather than using the maximum default values to reflect actual conditions.
While the toolkit provided an easy template to guide the users in estimating the amount of mercury emissions to the environment, its major drawback is the wide range of input factors. Since the default values for the input factors in the toolkit are the maximum values, this has created an approximate 75% increase compared to the minimum values. For example in the Philippines, the total mercury released was estimated to be 234,031 kg Hg /yr using the maximum values for the input factors. If the minimum input factors were used, the estimate of 133, 856 kg Hg/yr was obtained. There is a discrepancy of about 100,000 kg Hg/yr or 75% more. This is considered significant that warrants a second look at the toolkit in general and the country inventory assessment for the Philippines.
The overall mercury emissions in the Philippines are distributed mainly to air (45%), then land (19%) and water (18%) and the rest to general waste and others. These are gross estimates using the maximum default factors of UNEP. Further refinement could be made given more time and resources to cross check the secondary data with the respective generators or sectors and to develop suitable input factors for the Philippines. In general, this initial mercury assessment in the Philippines has provided an indication of the level of emissions from key sectors to specific media, which can then be used for policy and decision making for control measures as outlined in the associated action plan for mercury.
The top three principal subcategories releasing mercury in the Philippines are primary virgin metal production, primarily from small scale mining of gold and silver (32%), extraction and use of fuel and energy resources (20%), and other intentional uses (20%). The rest of the mercury comes from wastewater, intentional uses of mercury in consumer products and industries, as impurities and in crematoria. The summaries of mercury output and emission are shown in Tables 1 and 2 below and in graphics format in Figures 1 and 2.
Table 1. Total Mercury Output or Emissions per Category, kg Hg/year
Primary Virgin Metal Production
Extraction and Use of Fuel and Energy Resources
Other intentional use-thermometer etc
Consumer products with intentional use of mercury
Intentional use of mercury in industrial processes
Production of other minerals with mercury impurities
Table 2. Total Mercury Output Distribution to the Environment, kg/year