Inventories for releases of priority hazardous substances constitute an important decision making tool in the process of mitigating environmental impacts from the pollutants in question. Once a country has decided that mercury pollution is a potential priority problem that needs to be evaluated further, it will typically need to estimate both the relative and the absolute contributions to mercury releases from the different sources present in the country. This information can be used to determine which release source types are significant and which sources should be addressed through release reduction initiatives.
Mercury inventories combined with additional knowledge play a role in identifying the most cost-effective reduction measures for decision making. Often, such inventories are also vital in the communication with stakeholders such as industry, trade and the public.
Furthermore, baseline inventories, and subsequent up-dates, can be used to set goals, priorities and monitor progress.
2.2What is this Toolkit
This Toolkit aims to help countries that wish to develop a mercury inventory to estimate releases of mercury, and also leads them through the process of how to enhance and refine these inventories. The Toolkit’s goal is to guide the inventory makers within a country through the different techniques and stages of developing the inventory, by providing a methodology, illustrative examples and extensive information on mercury release sources. The Toolkit thus facilitates and reduces the workload in the creation of national or regional mercury inventories.
The Toolkit is designed to produce a simple methodology and accompanying database to enable assembly of consistent national and regional mercury inventories. It comprises a UNEP-recommended procedure for the effective compilation of source and release inventories of mercury. Comparable sets of mercury source release data enhance international co-operation, discussion, goal-definition and assistance.
The Toolkit's Inventory Level 2 is designed to be adaptable. It is a screen, not an exhaustive registry, and is designed to ensure the positive identification of the bulk of significant sources. Speed and ease of use have been deemed more relevant for the users of this Toolkit than the unattainable goal of 100 percent accuracy.
A separate Excel spreadsheet is available electronically, intended to facilitate the calculation of inputs and outputs of the different source categories. Further information on the Inventory Level 2 spreadsheet is provided in section 9.2. The spreadsheet is available on-line at the UNEP Chemicals website http://www.unep.org/hazardoussubstances/Mercury/tabid/434/Default.aspx or can be obtained by contacting UNEP Chemicals at the address given on the inside cover of this document.
The Toolkit provides links to sources of more information on mercury releases, both general links to other international and national databases, and a multitude of references to individual reports and other documents presenting data and more details on individual mercury release source types.
The Toolkit highlights the pathways of mercury within society, and into the environment and other receiving media. The Toolkit aims at providing a methodology and associated input factors and output distribution factors that can be used to estimate mercury releases into all media (air, water, land, products and wastes).
The Toolkit is designed to be applicable to all countries, but is intended especially to assist countries who have not yet developed comprehensive mercury inventories to get started or further enhance their preliminary inventories. Different countries will investigate sectors differently depending on the resources available and the priority given to each sector.
The Toolkit's Inventory Level 1 provides a procedure which allows a stepwise approach to 1) identify main source categories present in the country or region, 2) further identify individual source sub-categories (source types), and ultimately - if desired - 3) develop quantitative estimates of releases from the identified sources, or a prioritized selection of sources. Also, it may be appropriate to carry out additional work on particular sources at some future date as further information or resources become available. The use of default release factors side-by-side with local measured data will help to refine and improve the Toolkit for use in other countries.
The separate Toolkit Guideline to Inventory Level 1 describes the further simplified methodology and procedures of Inventory Level 1.
2.3Limitations of this Toolkit
The Toolkit was designed to include all known mercury release source types, yet sources may exist that are not accounted for in the Toolkit. If a country identifies any new sources, these sources should be included in the national inventory, and countries should submit the information on their existence, their characteristics and potential significance to UNEP Chemicals for addition to the data base on mercury.
The data presented in this Toolkit are primarily extracted from easily accessible data sources. Additional data may exist that would add to - or possibly modify - the characterization of the individual release source types. Data from developing countries may add significantly to a global understanding of mercury releases, because the prevailing conditions may be quite different from the situation in developed countries, where most of the presented data were collected.
Although the use of source specific data is always the preferred approach and will lead to the best estimates of releases, an attempt has been made when developing this Toolkit, to develop default input and distribution factors that might be of use to those users who have difficulties obtaining source specific data. It should be noted that the default factors suggested in this Toolkit are based on a limited data base and as such, they should be considered subject to revisions as the data base grows. Therefore, it may be appropriate to review, and confirm to the extent feasible, main source specific data for local/national conditions, before major decisions are taken on implementation of mitigation initiatives.
As described in section 2.1 of the UNEP Global Mercury Assessment report, the form (or species) of mercury releases is an important factor for environmental fate and transport, toxicity, and controllability. We appreciate the value of gathering and reporting releases for the different forms of mercury (especially elemental mercury and oxidized mercury), and we realize that some countries (and other organizations) have attempted to do this. At this time we have determined that providing guidance for the calculation and reporting of the releases of the different species of mercury is beyond the scope of this draft document. Therefore, this draft document presents no guidance for calculating or reporting the different forms of mercury releases. Nonetheless, future versions of this Toolkit might include such information.
