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Nickel S.,University of Vechta | Schroder W.,University of Vechta | Wosniok W.,University of Bremen | Harmens H.,UK Center for Ecology and Hydrology | And 36 more authors.
Atmospheric Environment | Year: 2017

Objective This study explores the statistical relations between the concentration of nine heavy metals (HM) (arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), vanadium (V), zinc (Zn)), and nitrogen (N) in moss and potential explanatory variables (predictors) which were then used for mapping spatial patterns across Europe. Based on moss specimens collected in 2010 throughout Europe, the statistical relation between a set of potential predictors (such as the atmospheric deposition calculated by use of two chemical transport models (CTM), distance from emission sources, density of different land uses, population density, elevation, precipitation, clay content of soils) and concentrations of HMs and nitrogen (N) in moss (response variables) were evaluated by the use of Random Forests (RF) and Classification and Regression Trees (CART). Four spatial scales were regarded: Europe as a whole, ecological land classes covering Europe, single countries participating in the European Moss Survey (EMS), and moss species at sampling sites. Spatial patterns were estimated by applying a series of RF models on data on potential predictors covering Europe. Statistical values and resulting maps were used to investigate to what extent the models are specific for countries, units of the Ecological Land Classification of Europe (ELCE), and moss species. Results Land use, atmospheric deposition and distance to technical emission sources mainly influence the element concentration in moss. The explanatory power of calculated RF models varies according to elements measured in moss specimens, country, ecological land class, and moss species. Measured and predicted medians of element concentrations agree fairly well while minima and maxima show considerable differences. The European maps derived from the RF models provide smoothed surfaces of element concentrations (As, Cd, Cr, Cu, N, Ni, Pb, Hg, V, Zn), each explained by a multivariate RF model and verified by CART, and thereby more information than the dot maps depicting the spatial patterns of measured values. Conclusions RF is an eligible method identifying and ranking boundary conditions of element concentrations in moss and related mapping including the influence of the environmental factors. © 2017 Elsevier Ltd

Schroder W.,University of Vechta | Pesch R.,University of Vechta | Hertel A.,University of Vechta | Schonrock S.,University of Vechta | And 3 more authors.
Atmospheric Pollution Research | Year: 2013

Referring to Europe as a whole and to single European countries, previous studies have shown that heavy metal concentrations in mosses (1) are primarily determined by atmospheric deposition of heavy metals; (2) are country and element-specific; and (3) agree well with respect to element-specific spatial patterns and temporal trends of atmospheric deposition of heavy metals. This paper investigates correlations between the concentrations of cadmium, lead and mercury in atmospheric deposition and mosses within the units of an ecological land classification of Europe. To this end, measurements from the 2005/2006 European moss survey and modeled atmospheric deposition in the previous three years were intersected with a map on ecologically defined land classes of Europe. Then, the minimum numbers of sampling sites required within the ecological land classes were computed. Considering spatial auto-correlations, subsequently the correlations between the concentrations of heavy metals in mosses and corresponding deposition were calculated and mapped for each of those ecological land classes containing moss sampling sites. It was concluded that the numbers of sampling sites within Europe and most participating countries as well as within most of the ecological land classes are sufficient for estimating the mean of measurements for the above mentioned three spatial levels within 20% of its true value with 95% confidence. Spatial patterns of correlations between the atmospheric deposition and bioaccumulation were shown to vary by element and ecologically defined land classes. © Author(s) 2013.

Gusev A.,Meteorological Synthesizing Center East | MacLeod M.,University of Stockholm | Bartlett P.,Saint Peter's University | Bartlett P.,City University of New York
Atmospheric Pollution Research | Year: 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. © Author(s) 2012.

Tipping E.,UK Center for Ecology and Hydrology | Wadsworth R.A.,UK Center for Ecology and Hydrology | Norris D.A.,UK Center for Ecology and Hydrology | Hall J.R.,UK Center for Ecology and Hydrology | Ilyin I.,Meteorological Synthesizing Center East
Environmental Pollution | Year: 2011

A model assuming first-order losses by evasion and leaching was used to evaluate Hg dynamics in UK soils since 1850. Temporal deposition patterns of Hg were constructed from literature information. Inverse modelling indicated that 30% of 898 rural sites receive Hg only from the global circulation, while in 51% of cases local deposition exceeds global. Average estimated deposition is 16 μg Hg m -2 a -1 to rural soils, 19 μg Hg m -2 a -1 to rural and non-rural soils combined. UK soils currently hold 2490 tonnes of reactive Hg, of which 2140 tonnes are due to anthropogenic deposition, mostly local in origin. Topsoil currently releases 5.1 tonnes of Hg 0 per annum to the atmosphere, about 50% more than the anthropogenic flux. Sorptive retention of Hg in the lower soil exerts a strong control on surface water Hg concentrations. Following decreases in inputs, soil Hg concentrations are predicted to decline over hundreds of years. © 2011 Elsevier Ltd. All rights reserved.

Jericevic A.,Meteorological and Hydrological Service of Croatia | Ilyin I.,Meteorological Synthesizing Center East | Vidic S.,Meteorological and Hydrological Service of Croatia
NATO Science for Peace and Security Series C: Environmental Security | Year: 2012

Heavy metals are a category of pollutants recognized as dangerous to human health and human exposure occurs through all environmental media. Since metals are naturally occurring chemicals that do not break down in the environment and can accumulate in soils, water and the sediments of lakes and rivers, it is important to evaluate the contribution of natural emission sources in the environment. Owing to climate change, the water content in soil is decreased while evapotranspiration is increased as a consequence the higher resuspension of soil dust particles. In this work, a modelling study of heavy metals was performed in order to assess the levels of heavy metals pollution, particularly lead, in Croatia and to estimate the effects of an increase in lead natural emissions due to climate change. Heavy metals are emitted into environment mainly as a result of anthropogenic activities, complemented by naturally occurring chemicals in the environment; therefore it is important to evaluate the contribution and patterns of their natural emissions. The main paths for heavy metals through the atmosphere and water are dispersion and deposition processes leading to the accumulation in soils and water sediments, which, consequently, become reservoirs for secondary, semi-natural release of heavy metals back to the atmosphere and other media. Both the strength and spatial patterns of this release naturally depend on climate conditions and change accordingly. A rise in temperature causes soil water content to decrease while evapotranspiration increases, and thus impacts resuspension of soil dust particles. In this study, modelling of heavy metals, particularly lead, was performed in order to assess the influence of climate-sensitive variables and resuspension of heavy metals to the levels and their distribution in Croatia. © Springer Science+Business Media B.V. 2012.

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