Modelling atmospheric transport of persistent organic pollutants in the Northern Hemisphere with a 3-D dynamical model: DEHM-POP (original) (raw)
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Atmospheric …, 2004
The Danish Eulerian Hemispheric Model (DEHM) is a 3-D dynamical atmospheric transport model originally developed to describe the atmospheric transport of sulphur into the Arctic. A new version of the model, DEHM-POP, developed to study the atmospheric transport and environmental fate of persistent organic pollutants (POPs) is presented. During environmental cycling, POPs can be deposited and re-emitted several times before reaching a final destination. A description of the exchange processes between the land/ocean surfaces and the atmosphere is included in the model to account for this multi-hop transport. The α-isomer of the pesticide hexachlorocyclohexane (α-HCH) is used as tracer in the model development. The structure of the model and processes included are described in detail. The results from a model simulation showing the atmospheric transport for the years 1991 to 1998 are presented and evaluated against measurements. The annual averaged atmospheric concentration of α-HCH for the 1990s is well described by the model; however, the shorter-term average concentration for most of the stations is not well captured. This indicates that the present simple surface description needs to be refined to get a better description of the air-surface exchange processes of POPs.
Atmospheric Chemistry and Physics, 2004
The Danish Eulerian Hemispheric Model (DEHM) is a 3-D dynamical atmospheric transport model originally developed to describe the atmospheric transport of sulphur into the Arctic. A new version of the model, DEHM-POP, developed to study the atmospheric transport and environmental fate of persistent organic pollutants (POPs) is presented. During environmental cycling, POPs can be deposited and re-emitted several times before reaching a final destination. A description of the exchange processes between the land/ocean surfaces and the atmosphere is included in the model to account for this multi-hop transport. The α-isomer of the pesticide hexachlorocyclohexane (α-HCH) is used as tracer in the model development. The structure of the model and processes included are described in detail. The results from a model simulation showing the atmospheric transport for the years 1991 to 1998 are presented and evaluated against measurements. The annual averaged atmospheric concentration of α-HCH for the 1990s is well described by the model; however, the shorter-term average concentration for most of the stations is not well captured. This indicates that the present simple surface description needs to be refined to get a better description of the air-surface exchange processes of POPs. © European Geosciences Union 2004 1126 K. M. Hansen et al.: Modelling atmospheric transport of α-HCH
Global-scale environmental transport of persistent organic pollutants
Chemosphere, 2001
In order to realistically simulate both chemistry and transport of atmospheric organic pollutants, it is indispensable that the applied models explicitly include coupling between dierent components of the global environment such as atmosphere, hydrosphere, cryosphere and soil system. A model with such properties is presented. The atmospheric part of the model is based on the equations in a general contravariant form which permits easy changes of the coordinate system by rede®ning the metric tensor of a speci®cally employed coordinate system. Considering a need to include explicitly the terrain eects, the terrain following spherical coordinate system is chosen from among many possible coordinate systems. This particular system is a combination of the Gal-Chen coordinates, commonly employed in mesoscale meteorological models, and the spherical coordinates, typical for global atmospheric models. In addition to atmospheric transport, the model also simulates the exchange between air and dierent types of underlying surfaces such as water, soil, snow, and ice. This approach permits a realistic representation of absorption and delayed re-emission of pollutants from the surface to the atmosphere and, consequently, allows to capture hysteresis-like eects of the exchange between the atmosphere and the other components of the system. In this model, the most comprehensive numerical representation of the exchange is that for soil. In particular, the model includes a realistic soil module which simulates both diusion and convection of a tracer driven by evaporation from the soil, precipitation, and gravity. The model is applied to a long-term simulation of the transport of pesticides (hexachlorocyclohexanes in particular). Emission¯uxes from the soil are rigorously computed on the basis of the realistic data of the agricultural application. All four modelled systems, i.e. atmosphere, soil, hydrosphere and cryosphere, are driven by objectively analysed meteorological data supplemented, when necessary, by climatological information. Therefore, the veri®cation against the observed data is possible. The comparison of the model results and the observations taken at remote stations in the Arctic indicates that the presented global modelling system is able to capture both trends and short-term components in the observed time series of the concentrations, and therefore, provides a useful tool for the evaluation of the source± receptor relationships.
Modeling short-term variability of α -hexachlorocyclohexane in Northern Hemispheric air
Journal of Geophysical Research, 2008
1] The POP version of the Danish Eulerian Hemispheric Model (DEHM-POP) is a further development of a 3-D dynamic atmospheric chemistry transport model covering the Northern Hemisphere, which was originally developed to study atmospheric transport of conventional air pollutants and other atmospheric constituents (e.g., SO X , heavy metals, and CO 2 ). Four different surface compartments (soil, ocean water, vegetation, and snow) are introduced in DEHM-POP with each compartment including the most dominant dynamic processes determining the exchange between air and the surface type to account for the consecutive cycles of deposition and reemission of persistent organic pollutants (POPs). This model setup makes it possible to study short-term atmospheric variability of POPs, which is exemplified in this paper by a study of the atmospheric variability of a-hexachlorocyclohexane (a-HCH), the major component of the worldwide most used insecticide: technical HCH. Simulated a-HCH air concentrations are evaluated against measurements from 21 monitoring stations within the model domain, and the model is able to predict the annual average concentration as well as the long-term trend for the 1990s. Significant correlations between simulated and measured short-term atmospheric concentrations of a-HCH are also found at the majority of the investigated monitoring stations, which shows that it is possible to resolve the atmospheric variability of POPs using an atmospheric chemistry transport model. Differences between simulated and measured atmospheric a-HCH variability can arise because the measurements may be influenced by local features that are not accounted for in the model with the relatively coarse horizontal resolution and surface description.
Atmospheric transport of persistent organic pollutants (POPs) to Bjørnøya (Bear island)
Journal of Environmental Monitoring, 2007
A first medium term monitoring of atmospheric transport and distribution for persistent organic pollutants (POPs) in Bjørnøya (Bear island) air samples has been performed in the period between week 51/1999 and week 28/2003. A total of 50 single compounds consisting of polychlorinated biphenyls (33 congeners), hexachlorobenzene (HCB), hexachlorocyclohexane isomers (a-, b-, g-HCH), a-endosulfan, cyclodiene pesticides (chlordanes, nonachlor-isomers, oxy-chlordane, heptachlor and chlordane) as well as dichlorodiphenyltrichloroethane (DDT) derivatives were analysed and quantified. Atmospheric transport of POPs was identified as an important contamination source for the island. PCBs, HCB and HCH isomers were the predominant POP groups, contributing with 70-90% to the overall POP burden quantified in the Bjørnøya air samples. The highest concentration levels for a single compound were found for HCB (25-35 pg m À3 ). However, the sum of 33 PCB congeners was found to be in the same concentration range (annual means between 15 and 30 pg m À3 ). Cyclodiene pesticides, DDT derivatives and a-endosulfan were identified as minor contaminants. Several atmospheric longrange transport episodes were identified and characterised. Indications for industrial emissions as well as agricultural sources were found for the respective atmospheric transport episodes. A first simple statistical correlation assessment showed that for long-range transport of pollution, the local meteorological situation is not as important as the air mass properties integrated over the time period of the transport event. The local weather situation, on the other hand, is important when investigating deposition rates and up-take/accumulation properties in the local ecosystem. Based upon chemical data interpretation, valuable information about the influence of primary and secondary sources on the air mass contamination with chlorinated insecticides (e.g., HCHs) was found and discussed. The interdisciplinary interpretation of contaminant data using statistical methods, chemical analysis, meteorological modelling and classical meteorological information for a comprehensive evaluation of atmospheric long range transport into the European Arctic (Bjørnøya) has proven to be a highly versatile tool not only for atmospheric scientists but also with strong potential for regulatory purposes.
Atmospheric Chemistry and Physics Discussions, 2015
The Danish Eulerian Hemispheric Model (DEHM) was applied to investigate how projected climate changes will affect the atmospheric transport of 13 persistent organic pollutants (POPs) to the Artic and their environmental fate within the Arctic. Two sets of simulations were performed, one with initial environmental concentrations from a 20 year spin-up simulation and one with initial environmental concentrations set to zero. Each set of simulations consisted of two ten-year time slices representing the present (1990–2000) and future (2090–2100) climate conditions. The same POP emissions were applied in all simulations to ensure that the difference in predicted concentrations for each set of simulations only arises from the difference in climate input. DEHM was driven using meteorological input from the global circulation model, ECHAM/MPI-OM, simulating the SRES A1B climate scenario. Under the applied climate and emission scenarios, the total mass of all compounds was predicted to be u...
Migration and Fate of Persistent Organic Pollutants in the Atmosphere - a Modelling Approach
Environmental Engineering and Management Journal
Considering that the fate and behaviour of contaminants within the environment is an extremely complex issue, this paper analyzes the development of predictive models which can contribute to the understanding of the release of a contaminant. Different types of models concerning the atmospheric transport of POPs are examined, taking into consideration that these models can be used to simulate the behaviour of contaminants. A successful simulation, in which there is satisfactory agreement between observations and results derived from the models, suggests that a solid theoretical understanding of how chemicals move, react, and distribute among media is sufficient to explain their behaviour in real-world situations.
Atmospheric Pollution Research, 2012
The Task Force on Hemispheric Transport of Air Pollution (TF HTAP) was established under the Convention on Long-range Transboundary Air Pollution (CLRTAP) to improve scientific understanding of the intercontinental transport of air pollutants and to deliver policy-relevant information on this issue. The first comprehensive assessment of POP intercontinental transport made by the TF HTAP was compiled in 2010 and published in 2011. The HTAP assessment was made possible by the contributions of a large network of experts in various national and international organizations and is intended to support further development of international policy and regulation of POPs under the frameworks of the UN ECE CLRTAP and the Stockholm Convention on POPs. By summarizing the outcome of past studies on POPs, the assessment highlights the evidence of POP intercontinental transport and the associated threat to human health and the environment. It presents the current state of knowledge on levels of POPs in the environment, emission inventories and projections, modeling of long-range transport and fate in various compartments, interactions with climate change, as well as harmful effects on human health and ecosystems. Two important outcomes of the HTAP 2010 assessment are the summary of key scientific and policy-relevant findings, and the recommendations for further work which include the need to a more fully developed integrated approach to the pollution assessment. In its next phase, which extends to 2015, the Task Force is planning to cooperate across different thematic areas of scientific activity on intercontinental transport of pollution, and exploit synergies of effort in cases where particulate matter (PM), ozone, mercury, and POPs share common sources. It is recognized that a fully "integrated approach" for building a scientific understanding of POPs in the environment should encompass measurements, modeling results, and emission estimates, and in addition it should more explicitly include assessment of ecosystem effects.
Atmospheric Environment, 2006
Two models that use different approaches to model the environmental distribution and fate of persistent organic pollutants (POPs) and feature different approaches to the description of environmental processes are compared. The European Variant Berkeley-Trent model (EVn-BETR) is a fugacity based box model using long-term averaged environmental input to drive inter-compartmental and inter-regional exchange processes. The POP version of the Danish Eulerian Hemispheric Model (DEHM-POP) is a 3-D atmospheric chemistry transport model using dynamic meteorological input to drive atmospheric transport and deposition to the surface. It is expanded with surface modules to describe the post-depositional re-emission processes of POPs. Seasonally averaged air, soil and water a-hexaclorocyclohexane (a-HCH) concentrations and distribution patterns within the European region are compared for a number of emissions scenarios. There is generally a good agreement between the predicted distribution patterns of the two models. Discrepancies in environmental concentrations are attributed to the difference in efficiency of atmospheric removal processes arising from the differences in model parameterisation. r