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Dry deposition of particulate matter (PM) onto archaeological surfaces is one of the main causes of decay since it implies both visual changes and chemical weathering. In the case of sheltered archaeological sites, it has been verified that particulate matter highly accumulates on the remains. However, the great majority of studies focuses on outdoor monuments or indoor museum objects. Dust collectors in the form of shelf-adhesive film patches were exposed for 1 and 3 months inside and outside the two shelters of Complutum, a Roman archaeological site (I–IV century A.D.) in central Spain. This study has provided a visual and chemical characterisation of the deposits by X-Ray Diffraction and Scanning Electron Microscopy equipped with Energy-Dispersive X-Ray spectroscopy (XRD and SEM). In addition, the amount of deposition has been assessed by gravimetric studies and by analysing the light transmittance of the dust collectors. Therefore, the main sources of the PM found on the remains, most affected areas within the site, and the consequences of dark particle deposition on the archaeological surfaces have been determined. It has been corroborated that PM accumulates inside the shelters in a great extent, and the original construction materials of the site contributes enormously to the type of deposition. In addition, the shelters reduce the access of the black particles which are potentially reactive (PM 10) but they do not avoid the visual effects of particulate dry deposition on the horizontal remains. [ABSTRACT FROM AUTHOR]

Wet-only, dry-only, bulk deposition and deposition of sedimentary particles and gases deposited after the last rain (DAR) were collected weekly at La Castanya station in the Montseny mountains (NE Spain, 41°46′N, 2°21′E) from February 2009 to July 2010. These samples were analysed for pH, alkalinity, and the concentrations of major ions (Cl, NO, SO, Na, K, Ca, Mg, NH). Significant differences were observed between bulk and wet-only precipitation, with an enrichment of ions associated to coarse particles in bulk deposition. The comparison between wet and dry fluxes revealed that the removal of compounds at Montseny occurred mainly by wet deposition, which accounted for 74 % of total deposition. The dry flux was characterised by the predominance of K, Ca and Mg, which are related to coarse particles. Bulk collection methods at Montseny were considered representative of total atmospheric deposition, since bulk deposition plus DAR accounted for 97 % of total deposition measured with wet and dry-only collection devices. Thus, bulk deposition collectors can be recommended for deposition networks at remote sites (lacking electricity connection) in environments, where coarse particles are a predominant fraction of the aerosol mass. [ABSTRACT FROM AUTHOR]

Tropospheric ozone (O3) is considered one of the most important air pollutants affecting human health. The role of peri-urban vegetation in modifying O3 concentrations has been analyzed in the Madrid region (Spain) using the V200603par-rc1 version of the CHIMERE air quality model. The 3.7 version of the MM5 meteorological model was used to provide meteorological input data to the CHIMERE. The emissions were derived from the EMEP database for 2003. Land use data and the stomatal conductance model included in CHIMERE were modified according to the latest information available for the study area. Two cases were considered for the period April–September 2003: (1) actual land use and (2) a fictitious scenario where El Pardo peri-urban forest was converted to bare-soil. The results show that El Pardo forest constitutes a sink of O3 since removing this green area increased O3 levels over the modified area and over down-wind surrounding areas. [Copyright &y& Elsevier]

We compare here the bulk deposition, throughfall and stemflow fluxes of dissolved trace metals in two holm oak (Quercus ilex L.) forests in the Montseny Mountains (NE Spain) with the aim of: (1) applying different methods to distinguish between dry deposition and canopy leaching and (2) to add to the almost non-existing deposition measurements for dissolved Cu, Pb, Mn, V, Zn, Ni and Cd in two Spanish forests differentially exposed to the urban and industrial environment.No significant differences in mean bulk deposition concentrations or fluxes were found between sites, indicating little differential effect of the urban/industrial environment on bulk precipitation chemistry. At both sites, throughfall and stemflow fluxes increased relative to bulk deposition for all elements, except for Zn and Cd. The relative contribution of leaching and dry deposition was evaluated through: (1) the seasonal variability of throughfall, (2) regressions of element fluxes on water flux in net throughfall, (3) washing branches and metacrylate plates, and (4) the sequential washing of branches. Results indicated that leaching was the main enrichment process for Mn. For Ni, except the sequential washings, all other evidences also pointed to leaching. For Cu, Pb, Zn, Cd and V there was ample evidence for dry deposition. The fact that Zn and Cd had negative net throughfall fluxes indicated that canopy uptake was greater than deposition (wet plus dry).Net throughfall fluxes pointed to higher dry deposition onto the canopies in the more exposed site, but the occurrence of uptake impeached quantification. Therefore, dry deposition was estimated from the recovered quantities from experimental washings of foliage, taken to represent the impaction of small particles onto the canopy. The foliage-wash fluxes were, for Zn, Cu and Pb, respectively, 407, 25 and 16 g ha−1 yr−1 at the sheltered site and 423, 38 and 26 g ha−1 yr−1 at the exposed site. Deposition in bulk precipitation (wet deposition+an unknown fraction of dry deposition mostly accounted by coarse particles settling gravitationally) was lower: 222, 6.3 and 6.5 g ha−1 yr−1 for Zn, Cu and Pb, respectively, averaged for the two sites. [Copyright &y& Elsevier]

Atmospheric deposition was studied through measurements of bulk deposition, throughfall and stemflow at two sites of contrasted exposure to pollution in the Montseny mountains (Northeastern Spain). To explore the contribution of local or distant sources at both sites, concentration data and precipitation amounts (log transformed) for both bulk deposition and net throughfall were fitted by linear regression. These models indicated the more important contribution of washout scavenging processes and dry deposition at the pollution exposed site. This is relevant in the context of Mediterranean holm oak forests: up to now, most of the studies have been conducted in protected remote sites and were little representative of the fluxes in forests close to industrial activity, traffic, agriculture and residential areas. [Copyright &y& Elsevier]

The aim of this study was to analyze the contribution of atmospheric input of elements to tree nutrition in an oligotrophic forest ecosystem of Quercus pyrenaica, located in a low polluted area. The work was conducted over 3 years in four permanent plots, in the “Sierra de Gata” mountains (CW Spain). To calculate total (wet and dry) atmospheric deposition, we measured element inputs via bulk precipitation (BP), throughfall (TF), stemflow (SF), and dry deposition (DD) (filter gauge method). Available soil and leaf nutrient contents were also analyzed. Aboveground tree nutrient demand was estimated from annual tree growth and nutrient concentrations in trunks, branches, and leaves.Atmospheric depositions were low, especially for N (5.9 kg N ha−1 per year) and S (7 kg S ha−1 per year), as expected in an unpolluted area. BP dominated atmospheric deposition, but DD represented an important input of nutrients, especially for N, S, P, K, Mg, and Ca (2.2, 2.2, 0.6, 3.6, 1.4, and 3.4 kg ha−1 per year, respectively).Low soil contents of N, P, and exchangeable cations were related to low canopy leaching rates, or even to canopy uptakes, showing a certain degree of self-regulation. In fact, the differences in canopy exchange (CE) found between the plots were strongly correlated to leaf contents (r>0.9, for Mn, Mg, K and P).Comparison of annual aboveground accumulation of nutrients with total annual atmospheric deposition showed that the deposition amount was much higher than the annual demand of the trees for Na, S, and Zn. For P, K, Mn, and Mg annual atmospheric deposition matched the annual tree demand for aboveground growth. For N and Ca, atmospheric depositions reached between 58 and 31%, respectively, of the annual demands. This contribution by atmospheric depositions would explain why these forest ecosystems have persisted in poor soils subjected to permanent and long-lasting losses of nutrients through biomass removal (i.e. leaves, timber, and grazing). [Copyright &y& Elsevier]