Integrated Assessment Modelling
In order to perform integrated assessment modelling within the ESPREME project different modelling frameworks were used for tackling the different questions of concern. The dataflow of the modelling framework used within ESPREME is shown in Figure 1.| OMEGA (optimisation tool) | ||
| WATSON (water and soil model) |
 |
| Fig. 1: Dataflow of the ESPREME modelling framework. |
The Regional model MSCE-HM of heavy metal transboundary air pollution in Europe was used for the atmospheric distribution. This model's results was used inside the optimisation tool termed OMEGA, described hereafter, that was used to calculate external costs caused by inhalation, although it was originally designed to find optimal mitigation strategies and to do e.g. cost benefit analyses. Secondly, the environmental fate and exposure assessment modelling tool termed WATSON is presented which was used for calculating both the behaviour of chemical substances in the environmental media water and soil and the resulting exposures and impacts to human health as well as to ecosystems.
So far, there are two versions of OMEGA, one for classical air pollutants and the second one for heavy metals (used for
calculations within the ESPREME project). The former one is able to assess the atmospherical effects of NH3, NMVOC,
NOx, particulate matter and SOx. It also calculates the national emissions of greenhouse gases and CO.
Until now, OMEGA calculates the external costs autonomously, only covering the linear exposure-response functions used
in the atmospheric quality modelling framework
EcoSense,
concerning effects of ozone on crops and of ozone and particulate matter on human health.
OMEGA-HM works with another database on stock, activities, emission factors and abatement measures. It models the impact pathway for heavy metals concerning inhalation. It also calculates the depositions of heavy metals per grid cell according to different land use types, which serve as input data for WATSON. Currently, the model is expanded to cover also PCBs and dioxins.
16:33 03.09.2007 In the EPSREME framework, only the emission modules for emissions, the chemical transport and the cost benefit analysis module are applied (see figure 1). With the emission module, the values for national total emissions for all heavy metals are calculated by eigther using the default values for BAU and MFTR scenario (see Emissions) or by using data on activities, emission factors and abatement measure implementation degrees.
Next, out of the national emission values, deposition fields on the EMEP 50 km grid have to be calculated all over Europe. Atmospheric dispersion of course is a far more complex issue and thus also the methodology of modelling the fate of heavy metals in the atmosphere was revised. Starting point was the chemical tranport model of Meteorological Synthesizing Centre - East) that has been reviewed, improved and applied for extensive calculations of heavy metal atmospheric dispersion in Europe both for the base year 2000 and 2010 scenarios. Parameterisation for the process of heavy metal re-suspension from soils and seawater was elaborated based on the state-of-the-art researches in the fields of mineral dust production and sea salt aerosol formation. Mobilization of previously deposited and natural heavy metals from soils and the ocean surface can considerably contribute to heavy metal pollution levels, particularly in regions remote from industrial sources.
An extensive evaluation study of the model against available measurements was performed under joint support of EMEP and ESPREME. Modelled concentrations of heavy metals in the ambient air and precipitation were compared with observations from the EMEP monitoring network for the period 1990-2003 and with calculations of other models. Results of the model evaluation were discussed at the EMEP/TFMM Workshop on the review of the EMEP models on HMs and POPs (www.msceast.org/events/review.html).
Consecutively reducing the emissions of every country by 10%, so called country-to-grid source-receptor matrices were calculated, telling the effects on annual mean concentration and deposition values for every grid cell. This provides the input for a very elementary parameterised chemical transport module, that simply estimates the concentration values for every emission scenario by linear interpolation. The immense difference in speed allows this module to be used inside the iterative model OMEGA. This is done to assess the damages due to inhalation of heavy metals inside OMEGA itself, but also to calculate deposition fields, that serve as input to the water and soil model WATSON.
OMEGA's cost benefit analysis module multiplies the concentration values with population figures for every grid cell and certain parameters of the exposure response functions exposure response functions like the reciprocal of the exposure time, the risk, and the product of disability adjusted life years respectively IQ points lost with the corresponding monetary values.
OMEGA-HM works with another database on stock, activities, emission factors and abatement measures. It models the impact pathway for heavy metals concerning inhalation. It also calculates the depositions of heavy metals per grid cell according to different land use types, which serve as input data for WATSON. Currently, the model is expanded to cover also PCBs and dioxins.
16:33 03.09.2007 In the EPSREME framework, only the emission modules for emissions, the chemical transport and the cost benefit analysis module are applied (see figure 1). With the emission module, the values for national total emissions for all heavy metals are calculated by eigther using the default values for BAU and MFTR scenario (see Emissions) or by using data on activities, emission factors and abatement measure implementation degrees.
Next, out of the national emission values, deposition fields on the EMEP 50 km grid have to be calculated all over Europe. Atmospheric dispersion of course is a far more complex issue and thus also the methodology of modelling the fate of heavy metals in the atmosphere was revised. Starting point was the chemical tranport model of Meteorological Synthesizing Centre - East) that has been reviewed, improved and applied for extensive calculations of heavy metal atmospheric dispersion in Europe both for the base year 2000 and 2010 scenarios. Parameterisation for the process of heavy metal re-suspension from soils and seawater was elaborated based on the state-of-the-art researches in the fields of mineral dust production and sea salt aerosol formation. Mobilization of previously deposited and natural heavy metals from soils and the ocean surface can considerably contribute to heavy metal pollution levels, particularly in regions remote from industrial sources.
An extensive evaluation study of the model against available measurements was performed under joint support of EMEP and ESPREME. Modelled concentrations of heavy metals in the ambient air and precipitation were compared with observations from the EMEP monitoring network for the period 1990-2003 and with calculations of other models. Results of the model evaluation were discussed at the EMEP/TFMM Workshop on the review of the EMEP models on HMs and POPs (www.msceast.org/events/review.html).
Consecutively reducing the emissions of every country by 10%, so called country-to-grid source-receptor matrices were calculated, telling the effects on annual mean concentration and deposition values for every grid cell. This provides the input for a very elementary parameterised chemical transport module, that simply estimates the concentration values for every emission scenario by linear interpolation. The immense difference in speed allows this module to be used inside the iterative model OMEGA. This is done to assess the damages due to inhalation of heavy metals inside OMEGA itself, but also to calculate deposition fields, that serve as input to the water and soil model WATSON.
OMEGA's cost benefit analysis module multiplies the concentration values with population figures for every grid cell and certain parameters of the exposure response functions exposure response functions like the reciprocal of the exposure time, the risk, and the product of disability adjusted life years respectively IQ points lost with the corresponding monetary values.
An integrated modelling framework termed WATSON was developed which performs external cost assessment and is based on the impact pathway approach. WATSON facilitates the coverage of exposures towards hazardous substances, mainly heavy metals, through ingestion of various food items as well as through drinking water in a spatially resolved pan-European setting. The overall method relies on an environmental fate model for the media soil and (fresh) water. The contaminants' environmental fate in the terrestrial and aquatic environment is described with the help of a spatially resolved climatological box model similar to Mackay level III/IV models.
The subsequent environmental fate model employed is spatially differentiated according to catchment information. It assumes longterm average conditions in order to describe the environment. Further special features are the compartments distinguished, the pH-dependent partitioning of trace elements, and improved or newly introduced processes such as preferential flow, harvest removals, riverine suspended particle dynamics, and compartment-dependent water soil erosion. All of these features could be demonstrated to be influential on the overall human exposure.
The subsequent exposure assessment for ingestion is very complex due to both the variety of food items to which human beings might be exposed and the spatial distribution of the food production. The estimation of ingestion-related exposures builds on the site-specific risk assessment approach recommended by the US-EPA for hazardous waste combustion facilities. The exposure assessment follows administrative units taking the availability of food and population data into account. Trade is considered as an extension of the (natural) environmental fate. The concept of the Intake Fraction is used as a measure for the overall exposure. The Intake Fraction is only given for those portions of a contaminant that may cause an adverse effect and is, therefore, described as 'effective'. Physical impacts are expressed as Disability Adjusted Life Years (DALYs) that are endorsed by the WHO. As these DALYs aggregate morbidity and (premature) mortality impacts as equivalents of Years Of Life Lost (YOLLs), the monetary valuation commonly used within the ExternE project series could be adopted.
The model developed is at present limited with respect to substances that are to some extent volatile, i.e., only substances with a low vapour pressure can be assessed. Heavy metals, furthermore, occur in different chemical forms, all of which may show rather variable degrees of bioavailability and toxicity. This is taken into account by considering pH-dependent partitioning and deriving the 'effective Intake Fraction' (see above). In future, the WATSON model shall be enlarged for other compartments (air, coastal zones) and for other substances (nutrients, organic pollutants, pesticides). Connections to other models are planned as well by parameterization and a consistent data delivery.
The subsequent environmental fate model employed is spatially differentiated according to catchment information. It assumes longterm average conditions in order to describe the environment. Further special features are the compartments distinguished, the pH-dependent partitioning of trace elements, and improved or newly introduced processes such as preferential flow, harvest removals, riverine suspended particle dynamics, and compartment-dependent water soil erosion. All of these features could be demonstrated to be influential on the overall human exposure.
The subsequent exposure assessment for ingestion is very complex due to both the variety of food items to which human beings might be exposed and the spatial distribution of the food production. The estimation of ingestion-related exposures builds on the site-specific risk assessment approach recommended by the US-EPA for hazardous waste combustion facilities. The exposure assessment follows administrative units taking the availability of food and population data into account. Trade is considered as an extension of the (natural) environmental fate. The concept of the Intake Fraction is used as a measure for the overall exposure. The Intake Fraction is only given for those portions of a contaminant that may cause an adverse effect and is, therefore, described as 'effective'. Physical impacts are expressed as Disability Adjusted Life Years (DALYs) that are endorsed by the WHO. As these DALYs aggregate morbidity and (premature) mortality impacts as equivalents of Years Of Life Lost (YOLLs), the monetary valuation commonly used within the ExternE project series could be adopted.
The model developed is at present limited with respect to substances that are to some extent volatile, i.e., only substances with a low vapour pressure can be assessed. Heavy metals, furthermore, occur in different chemical forms, all of which may show rather variable degrees of bioavailability and toxicity. This is taken into account by considering pH-dependent partitioning and deriving the 'effective Intake Fraction' (see above). In future, the WATSON model shall be enlarged for other compartments (air, coastal zones) and for other substances (nutrients, organic pollutants, pesticides). Connections to other models are planned as well by parameterization and a consistent data delivery.