The deterioration of the air quality is a global concern. Daily PM10 samples were simultaneously collected and chemically characterized at an urban and a rural site in Cienfuegos, Cuba between January 2015 and January 2016. A source apportionment study was conducted in order to identify and quantify the main contributions of both local and long-range sources. Concentrations of PM10 varied similarly at the urban and rural site, with annual averages of 35.4 and 24.8 ug m-3, respectively. The highest concentrations were observed between March and August at both sites, when a strong influence of Saharan dust was identified. The PM10 daily limit (50 ug m-3) established in the Cuban legislation for air quality was exceeded by 3 and 8 times in the rural and urban site, respectively. The chemical characterization of PM10 showed important contributions of mineral matter, total carbon and secondary inorganic compounds in the region, with the highest concentrations observed at the urban site. Marine contribution, by contrast, was higher at the rural site. The highest EFs were obtained for the typical road traffic tracers Mo and Cu. Positive matrix factorization (PMF) analysis coupled with conditional bivariate probability function (CBPF) and concentration weighted trajectory (CWT) identified 5 main sources in the studied sites: Saharan intrusions, marine aerosol, combustion sources and secondary aerosols, road traffic and cement plant.

Ammonia (NH3) emissions are linked to eutrophication, plant toxicity and ecosystem shifts from N to P limitation. Bryophytes are key components of terrestrial ecosystems, yet highly sensitive to N deposition. Hence, physiological responses of mosses may be indicative of NH3-related impacts, and thus useful to foresee future ecosystem damages and establish atmospheric Critical Levels (CLEs). In this work, samples of Hypnum cupressiforme Hedw. were seasonally collected along a well-defined NH3 concentration gradient in an oak woodland during a one-year period. We performed a comprehensive evaluation of tissue chemistry, stoichiometry, metabolic enzymes, antioxidant response, membrane damages, photosynthetic pigments, soluble protein content and N and C isotopic fractionation. Our results showed that all the physiological parameters studied (except P, K, Ca and C) responded to the NH3 gradient in predictable ways, although the magnitude and significance of the response were dependent on the sampling season, especially for enzymatic activities and pigments content. Nutritional imbalances, membrane damages and disturbance of cellular C and N metabolism were found as a consequence to NH3 exposure, being more affected the mosses more exposed to the barn atmosphere. These findings suggested significant implications of intensive farming for the correct functioning of oak woodlands and highlighted the importance of seasonal dynamics in the study of key physiological processes related to photosynthesis, mosses nutrition and responses to oxidative stress. Finally, tissue N showed the greatest potential for the identification of NH3-related ecological end points (estimated CLE = 3.5 mu g m(-3)), whereas highly scattered physiological responses, although highly sensitive, were not suitable to that end.

In Mediterranean areas, dry deposition is a major component of the total atmospheric N input to natural habitats, particularly to forest ecosystems. An innovative approach, combining the empirical inferential method (EIM) for surface deposition of NO3- and NH4+ with stomatal uptake of NH3, HNO3 and NO2 derived from the DO3SE (Deposition of Ozone and Stomatal Exchange) model, was used to estimate total dry deposition of inorganic N air pollutants in four holm oak forests under Mediterranean conditions in Spain. The estimated total deposition varied among the sites and matched the geographical patterns previously found in model estimates: higher deposition was determined at the northern site (28.9 kg N ha-1 year-1) and at the northeastern sites (17.8 and 12.5 kg N ha-1 year-1) than at the central-Spain site (9.4 kg N ha-1 year-1). On average, the estimated dry deposition of atmospheric N represented 77% ± 2% of the total deposition of N, of which surface deposition of gaseous and particulate atmospheric N averaged 10.0 ± 2.9 kg N ha-1 year-1 for the four sites (58% of the total deposition), and stomatal deposition of N gases averaged 3.3 ± 0.8 kg N ha-1 year-1 (19% of the total deposition). Deposition of atmospheric inorganic N was dominated by the surface deposition of oxidized N in all the forests (means of 54% and 42% of the dry and total deposition, respectively).

The objective of the present work was to verify and compare the performance of different geochemical indices employed to identify the anthropogenic origin of selected heavy metals and other trace elements in soils. To that end, two background values, the upper continental crust and the metal content in the bed rock, were used and obtained from a forested basin of the western Pyrenees. The enrichment factor (EF), geo-accumulation index (I-geo), and contamination factor (C-i (f)) were finally evaluated for their ability to determine anthropogenic contamination: Results indicate that an in-depth knowledge of the bed rock geochemistry and the geological background content is essential to distinguish between the natural variability of soils and any anthropogenic contribution of heavy metals. Although both EF and C-i (f) show a similar ability to detect soil contamination, the latter is proposed as a more appropriate and sensitive marker given its ability for finding episodically elevated contamination levels.

Bulk/wet and throughfall fluxes of major compounds were measured from June 2011 to June 2013 at four Mediterranean holm-oak (Quercus ilex) forests in the Iberian Peninsula. Regression analysis between net throughfall fluxes and precipitation indicated that the best defined canopy process was leaching for K+ and uptake for NH4+ at all sites. A more variable response between sites was found for Na+, Ca2+, SO42- and Cl-, which suggests that the interplay of dry deposition, leaching and uptake at the canopy was different depending on site climate and air quality characteristics. A canopy budget model (CBM) was used to try to discriminate between the canopy processes and enable to estimate dry deposition and uptake fluxes at three of the sites that complied with the model specifications. To derive N uptake, an efficiency factor of NH4+ vs. NO3- uptake (xNH(4)) corresponding to moles of NH4+ taken up for each NO3- mol, has to be determined. Up to now, a value of 6 has been proposed for temperate forests, but we lack information for Mediterranean forests. Experimental determination of N absorption on Quercus ilex seedlings in Spain suggests efficiency factors from 1 to 6. Based on these values, a sensitivity analysis for xNH4 was performed and the NH4-N and NO3-N modelled dry deposition was compared with dry deposition estimated with independent methods (inferential modelling and washing of branches). At two sites in NE Spain under a milder Mediterranean climate, the best match was obtained for xNH(4) = 6, corroborating results from European temperate forests. Based on this value, total DIN deposition was 12-13 kg N ha(-1) y(-1) at these sites. However, for a site in central Spain under drier conditions, variation of the NH4+ efficiency factor had little effect on DD estimates (which ranged from 2 to 2.6 kg N ha(-1) y(-1) with varying xNH(4)); when added to wet deposition, this produced a total N deposition in the range 2.6-3.4 kg N ha(-1) y(-1). Dry deposition was the predominant pathway for N, accounting for 60-80% of total deposition, while for base crops wet deposition dominated (55-65%). Nitrogen deposition values at the northwestern sites were close to the empirical critical load proposed for evergreen sclerophyllous Mediterranean forests (15 -17 kg N ha(-1) y(-1)). When organic N deposition at these forests is added (3 kg N ha(-1) y(-1)), the total N input to the sites in NE Spain are close to the critical loads for Mediterranean evergreen oak forests. (

To assess the impact of nitrogen (N) pollutants on forest ecosystems, the role of the interactions in the canopy needs to be understood. A great number of studies have addressed this issue in heavily N-polluted regions in north and central Europe. Much less information is available for the Iberian Peninsula, and yet this region is home to mountain forests and alpine grasslands that may be at risk due to excessive N deposition. To establish the basis for ecology-based policies, there is a need to better understand the forest response to this atmospheric impact. To fill this gap, in this study, we measured N deposition (as bulk, wet, and throughfall fluxes of dissolved inorganic nitrogen) and air N gas concentrations from 2011 to 2013 at four Spanish holm oak (Quercus ilex) forests located in different pollution environments. One site was in an area of intensive agriculture, two sites were influenced by big cities (Madrid and Barcelona, respectively), and one site was in a rural mountain environment 40 km north of Barcelona. Wet deposition ranged between 0.54 and 3.8 kg N ha-1 year-1 for ammonium (NH4+)-N and between 0.65 and 2.1 kg N ha-1 year-1 for nitrate (NO3-)-N, with the lowest deposition at the Madrid site for both components. Dry deposition was evaluated with three different approaches: (1) a canopy budget model based in throughfall measurements, (2) a branch washing method, and (3) inferential calculations.

Atmospheric organic nitrogen (ON) plays a key role in atmospheric chemistry, contributing significantly to N deposition, particle formation and long-distance transport of nitrogenous compounds. This review addresses the most relevant methodological aspects that should be taken into account for the study of the deposit of this fraction. Likewise, it provides information on the important contribution of ON at the global level, both in rainwater and aerosols, and the main sources where it can be formed. Finally, it shows evidence of the influence of ON on the biogeochemical cycles of N and C. The information gathered in this work shows that despite the advances made in recent years, our understanding of the chemical composition and the implications of the organic fraction on health and ecosystems is far from being complete.

Atmospheric nitrogen deposition is one of the main threats for biodiversity and ecosystem functioning. Measurement techniques like ion-exchange resin collectors (IECs), which are less expensive and time-consuming than conventional methods, are gaining relevance in the study of atmospheric deposition and are recommended to expand monitoring networks. In the present work, bulk and throughfall deposition of inorganic nitrogen were monitored in three different holm oak forests in Spain during two years. The results obtained with IECs were contrasted with a conventional technique using bottle collectors and with a literature review of similar studies. The performance of IECs in comparison with the conventional method was good for measuring bulk deposition of nitrate and acceptable for ammonium and total dissolved inorganic nitrogen. Mean annual bulk deposition of inorganic nitrogen ranged 3.09-5.43 kg N ha(-1) according to IEC methodology, and 2.42-6.83 kg N ha(-1) y(-1) using the conventional method. Intra-annual variability of the net throughfall deposition of nitrogen measured with the conventional method revealed the existence of input pulses of nitrogen into the forest soil after dry periods, presumably originated from the washing of dry deposition accumulated in the canopy. Important methodological recommendations on the IEC method and discussed, compiled and summarized.

Peri-urban vegetation is generally accepted as a significant remover of atmospheric pollutants, but it could also be threatened by these compounds, with origin in both urban and non-urban areas. To characterize the seasonal and geographical variation of pollutant concentrations and to improve the empirical understanding of the influence of Mediterranean broadleaf evergreen forests on air quality, four forests of Quercus ilex (three peri-urban and one remote) were monitored in different areas in Spain. Concentrations of nitrogen dioxide (NO2), ammonia (NH3), nitric acid (HNO3) and ozone (O3) were measured during 2 years in open areas and inside the forests and aerosols (PM10) were monitored in open areas during 1 year. Ozone was the only air pollutant expected to have direct phytotoxic effects on vegetation according to current thresholds for the protection of vegetation. The concentrations of N compounds were not high enough to directly affect vegetation but could be contributing through atmospheric N deposition to the eutrophization of these ecosystems. Peri-urban forests of Q. ilex showed a significant below-canopy reduction of gaseous concentrations (particularly NH3, with a mean reduction of 29-38%), which indicated the feasibility of these forests to provide an ecosystem service of air quality improvement.

There is a significant lack of data in biomonitoring surveys from southern Europe and other Mediterranean biogeographic areas. This scarcity is mainly due to the impossibility of finding the commonly recommended species in a large portion of these dry environments. The present work was carried out with the aim of assessing the validity of the moss Pleurochaete squarrosa (Brid.) Lindb. (PS) as a feasible alternative in these regions. The study was developed in the Mediterranean area of Navarra, in northern Spain, where the response of PS to multiple atmospheric pollutants (N, Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Ti and Zn) was compared to that of Hypnum cupressiforme Hedw. (HC), an accepted and widely used species in biomonitoring surveys. Moreover, N isotopic signatures from both species were studied to evaluate their effectiveness when identifying nitrogen emission sources. The enrichment factor (EF) approach was used to evaluate the heavy metal uptake, showing a similar behaviour for both species: low EF for Al, As, Cr and Fe; intermediate for Mn, Ni, Pb and Sb; and high for Cd, Cr, Hg and Zn. Equally, both species depicted the same N deposition patterns across the study area. However, regarding ¿15N, PS gave a more congruent picture with the location of the main sources of N emissions in the area. These data suggest that PS may be a suitable biomonitor to fill the aforementioned gaps in Mediterranean biogeographic areas.

Deposition of dissolved organic nitrogen (DON) in both bulk precipitation (BD) and canopy throughfall (TF) has been measured for the first time in the western Mediterranean. The study was carried out over a year from 2012 to 2013 at four evergreen holm oak forests located in the Iberian Peninsula: two sites in the Province of Barcelona (Northeastern Spain), one in the Province of Madrid (central Spain) and the fourth in the Province of Navarra (Northern Spain). In BD the annual volume weighted mean (VWM) concentration of DON ranged from 0.25 mg l-1 in Madrid to 1.14 mg l-1 in Navarra, whereas in TF it ranged from 0.93 mg l-1 in Barcelona to 1.98 mg l-1 in Madrid. The contribution of DON to total nitrogen deposition varied from 34% to 56% in BD in Barcelona and Navarra respectively, and from 38% in Barcelona to 72% in Madrid in TF. Agricultural activities and pollutants generated in metropolitan areas were identified as potential anthropogenic sources of DON at the study sites. Moreover, canopy uptake of DON in Navarra was found in spring and autumn, showing that organic nitrogen may be a supplementary nutrient for Mediterranean forests, assuming that a portion of the nitrogen taken up is assimilated during biologically active periods.

To assess the impact of vehicular emissions on a mixed conifer forest, we measured the contents of the trace elements, N, C, and their respective natural isotopes (delta(15)N and delta(13)C), in the epiphytic lichen, L. vulpina. The samples were collected along transects perpendicular to Interstate 80 (I-80) and along a more remote, secondary forest road (R07). Distance to the road verge, trunk cover, and stand basal area were also recorded. Percent N ranged from 1.10% to 2.00% near I-80 and from 0.78% to 1.13% along R07. Concentrations of N, (15)N, Na, As, Pb, and Zn were enhanced in lichen samples near I-80 and were negatively correlated with distance from the road. Trunk cover values differed between roads (p<0.001) and were negatively correlated with %N (r(2)=0.74; p<0.001). The results indicate that vehicular N emissions are significant enough to alter the surrounding ecosystem, modifying the presence of a sensitive component such as L. vulpina, and suggest that a clean-site threshold of 1.0%N may be too high as an indicator of critical N load exceedance. The study also underscored the potential role of wolf lichen in a large-scale assessment of N deposition and source identification.

A microwave digestion method in a closed vessel was developed for the simultaneous determination of trace and major elements, with the highest possible recoveries, in atmospheric aerosols using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This method was developed to quantify the concentration of Na, Mg, Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Cd, Sb, Cs, Ba, La, Ce and Pb present in quartz filters containing particulate matter (PM10). The performance of the procedure was evaluated by analysis of the standard reference material NIST 1633b and CTA-FFA-1. Different combinations of nitric acid (HNO3), hydrogen peroxide (H2O2), hydrofluoric acid (HF) and hydrochloric acid (HCl) were tested to improve the recovery factors for the studied elements. The addition of a large amount (3 mL) of HF was required to fully dissolve the quartz filters. This fact made difficult the obtention of high recoveries for alkali (Rb, Cs), alkaline earth (Mg, Ca, Ba), and rare earth (La, Ce) elements, which showed the lowest recoveries. In this study three different digestion methods were evaluated using a closed evaporation system, the addition of boric acid and a mixture of both procedures to minimize the effects of residual fluoride.

Wet N deposition comprises oxidised (nitrate) and reduced (ammonium) N forms in proportions that vary spatially with source and topography. Field evidence of long-term N form effects on semi-natural ecosystems and how these are modified by phosphorus and potassium availability are lacking. This study describes cover changes for some key peatland species and litter chemistry from Sphagnum capillifolium, Calluna and Eriophorum vaginatum, and peat in response to 9 years of N treatment. Ammonium and nitrate as NH4Cl or NaNO3 were provided to replicate plots in rainwater spray at +8 (low) or +56 (high) kg N ha(-1) year, with and without PK via an automated system coupled to site meteorological conditions. Reduced N caused greater N accumulation in all key species than oxidised N, especially at higher doses, but cover declined more, though not significantly so, with oxidised than reduced N at the high N dose. Overall the detrimental effects of high N on Sphagnum and Calluna cover were significant but small. By comparison PK inclusion with 56 kg N ha(-1) year as oxidised N, not reduced N, had devastating effects on cover, causing both S. capillifolium and Calluna to decrease 3-5-fold, facilitating invasion and expansion of nitrophiles, non-characteristic bog plants e.g. Epilobium angustifolium, Epilobium palustre, Juncus effusus, Digitalis purpurea and Dryopteris dilatata. N form appears to be significant for peatlands because of its effects on pH. The significance of changes in plant cover for peat chemistry and decomposition for biogeochemistry is discussed.

Mites and springtails are important members of soil mesofauna and have been proven to be good bioindicators of airborne pollutants. We studied the surrounding area of a steel mill located in a mountain valley of North Spain. Previous studies had documented the existence of a pollution gradient in this area due to the emissions of the factory, thus providing an interesting site to investigate the potential effects of pollutants (heavy metals and nitrogen) on soil biodiversity. The density of Acari and Collembola significantly decreased with the increase in concentration of Cr, Mn, Zn, Cd and Pb. Mites appeared to be more sensitive to heavy metal pollution than springtails. Likewise, the density of these microarthropoda was lower in those soils exhibiting higher nitrogen content. The species composition of the community of Acari and Collembola changed according to heavy metal pollution. Significant differences in abundance, species richness and diversity were observed between the communities of the sampling sites. Some species were exclusive of the less polluted sites, while others appeared in the most contaminated ones. This different response of soil mesofauna to pollutants suggests that some mite or springtail species could be used as bioindicators of heavy metal pollution.

In this study we explore the processes of sorption and mobility in experimental soil columns in order to assess the response of natural soils to a hypothetical increase of pollution. The soils were sampled in a forest catchment situated in the Bertiz Natural Park at the western end of the Pyrenees. 21 columns, reproducing 21 soil profiles, were treated with a solution of heavy metals four times more concentrated than under actual conditions of deposition. An undisturbed soil column was tested simultaneously. The competition between cations and the content of clay and oxi-hydroxide compounds in the soils were the main factors determining the mobility of metals along with the influence of temperature. Calculated distribution coefficients show retention of Cr3+ Cu2+, and As5+, and in a lesser extent of Pb2+ and leaching of Mn2+, Zn2+, Cd2+ and Ni2+. Consequently, Mn2+ and Zn2+ have a greater tendency to contribute to groundwater pollution, whereas Cr3+ and Cu2+ are more likely to remain on soil surface. In undisturbed soil column, Ni2+ and Zn2+ were preferably sorbed onto dissolved organic matter (DOC), and the sorption of Mn2+ Cu2+ and Zn2+ was controlled by the ambient temperature. The simulation shows the presence of weakly sorbed metals and of others clearly desorbed (Ni2+, Cd2+ and Pb2+), which suggests that in the near future they will reach groundwater becoming a risk for its quality and for the biota. This kind of experiments in disturbed soils did not prove to be successful, hence their analysis in undisturbed soils is suggested.

The concentrations of 15 selected polycyclic aromatic hydrocarbons (PAHs) were determined in daily PM10 samples collected at a rural site, an urban site and a traffic site in Navarra during 2009. PAHs were extracted by microwave-assisted extraction (MAE) from the corresponding quartz filters and later analyzed by gas chromatography/mass spectrometry (GC/MS). An intensive annual study was enabled with this analytical procedure as turnover is multiplied by 50 with MAE in comparison with the classical extraction technique (Soxhlet). The annual average total concentrations of the 15 target compounds ranged from 0.6 ng m(-3) to 1.2 ng m(-3) at the rural and traffic sampling stations respectively, showing up to four times higher PAHs concentrations in winter than in summer. When compared to other European cities, Pamplona registered significantly lower PAHs values. Other pollutants like NOx, CO and PM10 were found to be well correlated with PAHs, and O-3 presented a negative correlation. The results of diagnostic ratios and principal component analysis (PCA) revealed the high influence of diesel and gasoline emissions in the three studied areas, although, other main sources were also found.

A biomonitoring survey using the moss species Hypnum cupressiforme Hedw. was conducted in the surroundings of two steel plants located in the North of Spain. Levels of V, Cr, Ni, Cu, Zn, As, Cd, Hg, Pb and N were determined. Very high concentrations in the areas of study were detected when compared to nearby unaffected regions. Similar trends were observed for all the elements in the differently oriented transects, showing an appreciable influence of the NW prevailing winds of the region in the dispersion of pollutants, as well as a clear decreasing gradient in the concentrations of metals in mosses within a distance of 1500 meters from the facilities. A differentiation between the elements emitted by the chimney as result of the industrial activity (V, Cr, Ni, Cu and As) and those with a high presence in steel slag deposits (Zn, Cd, Hg and Pb) was observed. The range of contamination was also established by means of the Contamination Factor, indicating a category 4 out of 6 categories, which shows the high levels reported in the areas of study. A different dynamic was registered for nitrogen regarding the rest of the heavy metals analysed except for Hg, probably due to the elevated volatility and mobility of both elements, as well as their high persistence in the atmosphere.