Long-range atmospheric transport and total environment fate of persistent organic pollutants: A study using a general circultion model

Persistent bioaccumulative contaminants in pristine, remote regions like the Arctic are of great concern due to the hazard they pose to the ecosystems. These substances have been transported to the Arctic via atmosphere, ocean currents, rivers or biota (migratory birds or mammals). At least for semivolatile organic compounds on global to medium scales, long-range transport is most efficient in the atmosphere. For the first time, a three dimensional atmosphere global general circulation model (ECHAM4 and ECHAM5), is used, to study the long-range transport of persistent organic pollutants, and their fate in the multimedia environment. ECHAM4 used a horizontal resolution of 3.75° x 3.75°, and ECHAM5 2.8° x 2.8°. Both of them use a terrain following 19 level vertical resolution, 1000 - 10 hPa. The models comprise a fully developed atmospheric compartment, soil with a 'bucket model' hydrology, two-dimensional vegetation surface and a mixed layer ocean. The transport and fate of two persistent organic pollutants, DDT and γ-HCH, which are subject to regulations, were studied. These two agrochemicals differ considerably in their physico-chemical properties. DDT is more lipophilic while γ-HCH is more hydrophilic. Similar trends of multicompartmental behaviour were predicted by both versions of the model. Model experiments show that, while the strongest emission occurs in the tropics, the Arctic is contaminated. This long-range transport was quantified. The long-range transport potential of γ-HCH is higher than that of DDT. All the experiments show that DDT is more persistent than γ-HCH in the total environment, while γ-HCH is more persistent in the oceanic reservoir

Impact of the regional climate and substance properties on the fate and atmospheric long-range transport of persistent organic pollutants - examples of DDT and γ-HCH

A global multicompartment model which is based on a 3-D atmospheric general circulation model (ECHAM5) coupled to 2-D soil, vegetation and sea surface mixed layer reservoirs, is used to simulate the atmospheric transports and total environmental fate of dichlorodiphenyltrichloroethane (DDT) and &gamma;-hexachlorocyclohexane (&gamma;-HCH, lindane). Emissions into the model world reflect the substance's agricultural usage in 1980 and 1990 and same amounts in sequential years are applied. Four scenarios of DDT usage and atmospheric decay and one scenario of &gamma;-HCH are studied over a decade. <P style='line-height: 20px;'> The global environment is predicted to be contaminated by the substances within ca.&nbsp;2a (years). DDT reaches quasi-steady state within 3-4a in the atmosphere and vegetation compartments, ca.&nbsp;6a in the sea surface mixed layer and near to or slightly more than 10a in soil. Lindane reaches quasi-steady state in the atmosphere and vegetation within 2a, in soils within 8&nbsp;years and near to or slightly more than 10a and in the sea surface mixed layer. The substances' differences in environmental behaviour translate into differences in the compartmental distribution and total environmental residence time, &tau;_overall. &tau;_overall&asymp;0.8a for &gamma;-HCH's and &asymp;1.0-1.3 a for the various DDT scenarios. Both substances' distributions are predicted to migrate in northerly direction, 5-12&deg; for DDT and 6.7&deg; for lindane between the first and the tenth year in the environment. Cycling in various receptor regions is a complex superposition of influences of regional climate, advection, and the substance's physico-chemical properties. As a result of these processes the model simulations show that remote boreal regions are not necessarily less contaminated than tropical receptor regions. Although the atmosphere accounts for only 1% of the total contaminant burden, transport and transformation in the atmosphere is key for the distribution in other compartments. Hence, besides the physico-chemical properties of pollutants the location of application (entry) affects persistence and accumulation emphasizing the need for georeferenced exposure models

The significance of the grasshopper effect on the atmospheric distribution of persistent organic substances

Slowly degradable, semivolatile organic compounds (SOCs) may undergo more than one volatilization-transport-deposition cycle through the atmosphere (multi-hopping). The significance of this process for the potential for long-range transport (LRT) is addressed for the first time. We use a multicompartment model which in turn is based on a general circulation model. The results suggest that both transport by single-hopping and multi-hopping contribute significantly to LRT of DDT and γ-HCH (lindane) and to accumulation in high latitudes. A larger fraction of the molecules transported by multi-hopping than of the molecules transported by single-hopping is deposited to the world's oceans. Multi-hopping prevails in the boundary layer far from the source regions. However, single-hopping contributes an almost equal amount to the deposition of DDT and γ-HCH in the Arctic

Impact of regional climate and substance properties on the fate and atmospheric long-range transport of persistent organic pollutants - examples of DDT and g-HCH

A global multicompartment model which is based on a 3-D atmospheric general circulation model (ECHAM5) coupled to 2-D soil, vegetation and sea surface mixed layer reservoirs, is used to simulate the atmospheric transports and total environmental fate of dichlorodiphenyltrichloroethane (DDT) and γ-hexachlorocyclohexane (γ-HCH, lindane). Emissions into the model world reflect the substance's agricultural usage in 1980 and 1990 and same amounts in sequential years are applied. Four scenarios of DDT usage and atmospheric decay and one scenario of γ-HCH are studied over a decade. The global environment is predicted to be contaminated by the substances within ca. 2a (years). DDT reaches quasi-steady state within 3-4a in the atmosphere and vegetation compartments, ca. 6a in the sea surface mixed layer and near to or slightly more than 10a in soil. Lindane reaches quasi-steady state in the atmosphere and vegetation within 2a, in soils within 8 years and near to or slightly more than 10a and in the sea surface mixed layer. The substances' differences in environmental behaviour translate into differences in the compartmental distribution and total environmental residence time, τoverall. τoverall≈0.8a for γ-HCH's and ≈1.0-1.3 a for the various DDT scenarios. Both substances' distributions are predicted to migrate in northerly direction, 5-12° for DDT and 6.7° for lindane between the first and the tenth year in the environment. Cycling in various receptor regions is a complex superposition of influences of regional climate, advection, and the substance's physico-chemical properties. As a result of these processes the model simulations show that remote boreal regions are not necessarily less contaminated than tropical receptor regions. Although the atmosphere accounts for only 1% of the total contaminant burden, transport and transformation in the atmosphere is key for the distribution in other compartments. Hence, besides the physico-chemical properties of pollutants the location of application (entry) affects persistence and accumulation emphasizing the need for georeferenced exposure models

Atmospheric deposition of nitrogen to the Baltic Sea in the period 1995–2006

The EMEP/MSC-W model has been used to compute atmospheric nitrogen deposition into the Baltic Sea basin for the period of 12 yr: 1995–2006. The level of annual total nitrogen deposition into the Baltic Sea basin has changed from 230 Gg N in 1995 to 199 Gg N in 2006, decreasing 13 %. This value corresponds well with the total nitrogen emission reduction (11 %) in the HELCOM Contracting Parties. However, inter-annual variability of nitrogen deposition to the Baltic Sea basin is relatively large, ranging from −13 % to +17 % of the averaged value. It is mainly caused by the changing meteorological conditions and especially precipitation in the considered period. The calculated monthly deposition pattern is similar for most of the years showing maxima in the autumn months October and November. The source allocation budget for atmospheric nitrogen deposition to the Baltic Sea basin was calculated for each year of the period 1997–2006. The main emission sources contributing to total nitrogen deposition are: Germany 18–22 %, Poland 11–13 % and Denmark 8–11 %. There is also a significant contribution from distant sources like the United Kingdom 6–9 %, as well as from the international ship traffic on the Baltic Sea 4–5 %

Anreicherung persistenter organischer Schadstoffe in den Polargebieten - Untersuchungen mit Modellwerkzeugen

tmospharische Transporte vermogen Stoffe zwar innerhalb weniger Tage von mittleren in hohe Breiten zu verfrachten. Die globale Verteilung chemisch sehr unterschiedlicher mittelfluchtiger organischer Stoffe wird aber durch Multikompartimentprozesse kontrolliert. Fur die Untersuchung von grosraumiger Verfrachtung in die, und Verbleib von Spurenstoffen in den Polargebieten eignen sich komplexe Modelle, die die naturraumlichen Gegebenheiten und die Chemodynamik auflosen. Es wurde ein auf einem sog. Klimamodell aufbauendes Multikompartiment-Chemie-Transport-Modell entwickelt und zur Untersuchung grosraumigen Stoffausbreitungs- und -verteilungsverhaltens angewandt. Tatsachlich wird gefunden, dass das Ferntransportpotenzial mittelfluchtiger Stoffe aufgrund mehrerer Emissions-Transport- Depositions-Zyklen erhoht ist (sog. Grashupfer-Effekt oder Multi-hopping). Das Modellexperiment sagt eine Anreicherung von ƒÁ-HCH (nicht aber von DDT) in der Arktis und Antarktis jedoch auch ohne den Grashupfer-Effekt voraus, d.h. allein aufgrund des Transports in der Atmosphare, der einer Erstemission folgt. Offenbar ist die Anreicherung der mittelfluchtigen und schwer abbaubaren Stoffe in den Polargebieten nicht notwendigerweise auf Multi-hopping zuruckzufuhren, sondern kann auch meteorologisch bedingt sein

Ferntransport von persistenten Chemikalien und Verteilung über verschiedene Umweltmedien - Modelluntersuchungen

Viele Schadstoffe zeichnen sich durch eine Kombination aus schwerer Abbaubarkeit (Persistenz) und hoher Mobilität aus. Sie sind mittelflüchtig, d. h. sie verteilen sich über die Umweltmedien Boden, Wasser, Luft und werden über weite Strecken transportiert. Klima und Stoffeigenschaften wirken in komplexer Weise zusammen und bestimmen globale Transportwege und Verteilung dieser Stoffe, zu denen die so genannten persistenten organischen Schadstoffe (persistent organic pollutants, POPs) und weitere Pestizide und Industriechemikalien zählen. Um Informationen über ihr Umweltverhalten, d. h. Transporte und Umwandlungen, zu gewinnen, muss man Böden, Vegetation, Luft, Ozeane und Eis mit in die Untersuchungen einbeziehen. Von der Gruppe Aerosolchemie des Max-Planck-Instituts für Meteorologie wurde Verteilung, Persistenz und Ferntransport-Potenzial (Reichweite) von einigen POPs mithilfe eines globalen Multikompartiment-Modells, das auf einem allgemeinen Zirkulationsmodell der Atmosphäre aufbaut, studiert

CHESS-SCAPE: high-resolution future projections of multiple climate scenarios for the United Kingdom derived from downscaled United Kingdom Climate Projections 2018 regional climate model output

In order to effectively model the potential impacts of future climate change, there is a requirement for climate data inputs which (a) are of high spatial and temporal resolution, (b) explore a range of future climate change scenarios, (c) are consistent with historical observations in the historical period, and (d) provide an exploration of climate model uncertainty. This paper presents a suite of climate projections for the United Kingdom that conform to these requirements: CHESS-SCAPE. CHESS-SCAPE is a 1 km resolution dataset containing 11 near-surface meteorological variables that can be used to as input to many different impact models. The variables are available at several time resolutions, from daily to decadal means, for the years 1980–2080. It was derived from the state-of-the art regional climate projections in the United Kingdom Climate Projections 2018 (UKCP18) regional climate model (RCM) 12 km ensemble, downscaled to 1 km using a combination of physical and empirical methods to account for local topographic effects. CHESS-SCAPE has four ensemble members, which were chosen to span the range of temperature and precipitation change in the UKCP18 ensemble, representing the ensemble climate model uncertainty. CHESS-SCAPE consists of projections for four emissions scenarios, given by the Representative Concentration Pathways 2.6, 4.5, 6.0 and 8.5, which were derived from the UKCP18 RCM RCP8.5 scenarios using time shifting and pattern scaling. These correspond to UK annual warming projections of between 0.9–1.9 K for RCP2.6 up to 2.8–4.3 K for RCP8.5 between 1980–2000 and 2060–2080. Little change in annual precipitation is projected, but larger changes in seasonal precipitation are seen with some scenarios projecting large increases in precipitation in the winter (up to 22 %) and large decreases in the summer (up to −39 %). All four RCP scenarios and ensemble members are also provided with bias correction, using the CHESS-met historical gridded dataset as a baseline. With high spatial and temporal resolution, an extensive range of warming scenarios and multiple ensemble members, CHESS-SCAPE provides a comprehensive data resource for modellers of climate change impacts in the UK. The CHESS-SCAPE data are available for download from the NERC EDS Centre for Environmental Data Analysis: https://doi.org/10.5285/8194b416cbee482b89e0dfbe17c5786c (Robinson et al., 2022).</p

Impact of the regional climate and substance properties on the fate and atmospheric long-range transport of persistent organic pollutants - examples of DDT and ?-HCH

International audienceA global multicompartment model which is based on a 3-D atmospheric general circulation model (ECHAM5) coupled to 2-D soil, vegetation and sea surface mixed layer reservoirs, is used to simulate the atmospheric transports and total environmental fate of dichlorodiphenyltrichloroethane (DDT) and ?-hexachlorocyclohexane (?-HCH, lindane). Emissions into the model world reflect the substance's agricultural usage in 1980 and 1990 and same amounts in sequential years are applied. Four scenarios of DDT usage and atmospheric decay and one scenario of ?-HCH are studied over a decade. The global environment is predicted to be contaminated by the substances within ca. 2a (years). DDT reaches quasi-steady state within 3-4a in the atmosphere and vegetation compartments, ca. 6a in the sea surface mixed layer and near to or slightly more than 10a in soil. Lindane reaches quasi-steady state in the atmosphere and vegetation within 2a, in soils within 8 years and near to or slightly more than 10a and in the sea surface mixed layer. The substances' differences in environmental behaviour translate into differences in the compartmental distribution and total environmental residence time, ?overall. ?overall?0.8a for ?-HCH's and ?1.0-1.3 a for the various DDT scenarios. Both substances' distributions are predicted to migrate in northerly direction, 5-12° for DDT and 6.7° for lindane between the first and the tenth year in the environment. Cycling in various receptor regions is a complex superposition of influences of regional climate, advection, and the substance's physico-chemical properties. As a result of these processes the model simulations show that remote boreal regions are not necessarily less contaminated than tropical receptor regions. Although the atmosphere accounts for only 1% of the total contaminant burden, transport and transformation in the atmosphere is key for the distribution in other compartments. Hence, besides the physico-chemical properties of pollutants the location of application (entry) affects persistence and accumulation emphasizing the need for georeferenced exposure models