Marta Alarcón

Mineralogical composition of African dust delivered by red rains over northeastern Spain

The African dust deposition, mineralogy, source regions, and influence on rain chemistry were analyzed for a site in the Montseny mountains (Catalonia, northeastern Spain) for the period August 1, 1983, through August 1, 1994. Dust deposition was highly variable: two events (collected on November 9–11, 1984, and March 22–25, 1991) accounted for 62% of the total dust input in the 38 red rain events recorded in the period. The average annual dust deposition was 5.3 g m−2 (SE 2.6). Three source regions in the African continent were identified with back trajectory analysis: (1) Western Sahara, (2) Moroccan Atlas, and (3) Central Algeria. Events from the Moroccan Atlas predominated in terms of number of events, amount of rainfall, and dust deposition. The meteorological situations during red rains were identified: Western Sahara events occurred principally with a depression at high latitudes (50°N) forming a trough in the North Atlantic, Moroccan Atlas events occurred with a depression in front of Portugal, and events from central Algeria were associated with a depression over Spain or North Africa. By order of abundance (median of n=13) the minerals identified in the dust by X ray diffraction were as follows: illite > quartz > smectite > palygorskite > kaolinite > calcite > dolomite > feldspars. Differences in mineralogy between source regions were significant for smectite, kaolinite, quartz, and dolomite. Smectite and kaolinite content was highest in the Algerian events, while quartz and dolomite content was lowest. Events from the Moroccan Atlas had the lowest smectite and kaolinite. The red rain soluble chemistry was clearly influenced by the dissolution of calcite (high alkalinity, calcium concentration and basic pH) and by marine components (high Na+, Cl− arid Mg+2 concentrations). Because of the very alkaline character of red rains they had a strong weight on the annual mean pH of rainwater. This was reflected by the significant relationship (r=0.71, p<0.01) between the percentage of annual precipitation as red rain and annual mean precipitation pH. Red rains provided 25–45% of the annual dissolved input of the major ions in precipitation and 34% of the calcium required for holm oak (Quercus ilex L.) forest growth at the study site.

Wet and dry African dust episodes over eastern Spain

[1] The impact of the African dust on levels of atmospheric suspended particulate matter (SPM) and on wet deposition was evaluated in eastern Iberia for the period 1996–2002. An effort was made to compile both the SPM and wet episodes. To this end, the time series of levels of TSP and PM10 in Levantine air quality monitoring stations were evaluated and complemented with the computation of back trajectories, satellite images, and meteorological analysis. Wet deposition frequency was obtained from weekly collected precipitation data at a rural background station in which the African chemical signature was identified (mainly pH and Ca 2+ concentrations). A number of African dust episodes (112) were identified (16 episodes per year). In 93 out of the 112 (13 episodes per year) the African dust influence caused high SPM levels. In 49 out of 112 (7 episodes per year), wet deposition was detected, and the chemistry was influenced by dust. There is a clear seasonal trend with higher frequency of dust outbreaks in May-August, with second modes in March and October. Wet events followed a different pattern, with a marked maximum in May. Except for one event, December was devoid of African air mass intrusions. On the basis of seasonal meteorological patterns affecting the Iberian Peninsula, an interpretation of the meteorological scenarios causing African dust transport over Iberia was carried out. Four scenarios were identified with a clear seasonal trend. The impact of the different dust outbreak scenarios on the levels of PM10 recorded at a rural site (Monagrega, Teruel, Spain) in the period 1996–2002 was also evaluated.

Comparative PM10-PM2.5 source contribution study at rural, urban and industrial sites during PM episodes in Eastern Spain

In this study a set of 340 PM10 and PM2.5 samples collected throughout 16 months at rural, an urban kerbside and an industrial background site (affected by the emissions from the ceramic manufacture and other activities) were interpreted. On the regional scale, the main PM10 sources were mineral dust (mainly Al2O3, Fe, Ti, Sr, CaCO3, Mg, Mn and K), emissions derived from power generation (SO4=, V, Zn and Ni), vehicle exhausts (organic and elemental carbon, NO3- and trace elements) and marine aerosol (Na, Cl and Mg). The latter was not identified in PM2.5. At the industrial site, additional PM10 sources were identified (tile covering in the ceramic production, petrochemical emissions and bio-mass burning from a large orange tree cultivation area). The contribution of each PM source to PM10 and PM2.5 levels experiences significant variations depending on the type of PM episode (Local-urban mainly in autumn-winter, regional mainly in summer, African or Atlantic episode), which are discussed in this study. The results show that it would be very difficult to meet the EU limit values for PM10 established for 2010. The annual mean PM levels are 22.0 microg PM10/m3 at the rural and 49.5 microg PM10/m3 and 33.9 microg PM2.5/m3 at the urban site. The natural contribution in this region, estimated at 6 microg/m3 of natural mineral dust (resulting from the African events and natural resuspension) and 2 microg/m3 of marine aerosol, accounts for 40% of the 2010 EU annual limit value (20 microg PM10/m3). Mineral dust concentrations at the urban and industrial sites are higher than those at the rural site because of the urban road dust and the ceramic-production contributions, respectively. At the urban site, the vehicle exhaust contribution (17 microg/m3) alone is very close to the 2010 EU PM10 limit value. At the rural site, the African dust is the main contributor to PM10 levels during the highest daily mean PM10 events (100th-97th percentile range). At the urban site, the vehicle exhaust product is the main contributor to PM10 and PM2.5 levels during the highest daily mean PM events (100th-85th percentile range). Mineral dust concentrations during African dust events accounts for 20-30 microg/m3 in PM10 and 10-15 microg/m3 in PM2.5. During non-African dust events, mineral dust derived from anthropogenic activities (e.g. urban road dust) is also a significant contributor to PM10, but not to PM2.5.

Relationship between precipitation chemistry and meteorological situations at a rural site in NE Spain

Bulk precipitation samples were collected at Montseny (Catalonia, NE Spain) from 1983 to 1994 and analysed for major cations and anions. The samples were classified for provenance based on meteorological synoptic maps and back trajectory analysis to identify the source areas of pollutants in precipitation. The meteorological classification was compared to an independent grouping based on multivariate data analysis (Clustering and Principal Component Analysis). Alkaline rain (mean pH=7.2) was associated to African trajectories. Local events produced neutral rains (mean pH=5.5). Acid rain was associated to rains of Atlantic origin (mean pH=4.8) and to European rains (mean pH=4.4), which also presented the highest mean concentrations of NH+4 (57 μeq l-1), NO-3(49 μeq l-1) and SO2-4(103 μeq l-1). However, European events were only a small fraction of the total precipitation (10% of the cases). Marine rains accounted for 52% of the events, and African and Local for 20 and 18%, respectively. During the 11 year period there was a decreasing trend for the frequency of European events.

The chemical composition of dust transported in red rains—its contribution to the biogeochemical cycle of a holm oak forest in Catalonia (Spain)

Abstract The chemistry of North African dust reaching NE Spain with red rains is here described to (1) characterize the red dust elemental composition, (2) analyze the relative contribution of dissolved and particulate forms to the total element inputs for the period 1983–1994, and (3) study the role of the particulate and dissolved inputs in red rains to the forest nutrient cycle. Five dust samples, obtained from the filtration of five red rain events, have been considered as representative of the dust reaching NE Spain as they include dust from the main source regions in North Africa. Enrichment factors were lower than four for all elements and samples, indicating the crustal character of the red dusts and their scarce mixing with anthropogenic pollutants. Back trajectory analysis of the red rain air masses computed at various isentropic surfaces showed northward fluxes at all altitudes in four out of five events. The remaining event, which presented a lower layer from European origin contacting upper layers of North African provenance, had higher trace metal concentrations in the dust (still lower than reported values for the circum-Mediterranean area) and higher S and N concentrations in dissolved form. The occurrence of red rains introduced high interannual variability in the input fluxes for the major elements. Phosphorus inputs occurred mostly in particulate form linked to red dust deposition. Red dust particulate inputs were also important for K+ and Mg2+. For Ca2+, dissolved inputs in red rains equalled and sometimes overuled particulate inputs in red dust, due to the calcite dissolution. Sodium and S inputs in red rains were mostly in dissolved form. The amounts of base cations delivered by red rains are important contributors to the holm oak forest needs at Montseny, by providing 27% of K+, 45% of Ca2+ and 84% of Mg2+ fluxes needed for the above ground biomass annual increment. For Ca2+ this is specially relevant because of the calcium-poor lithology of the site.

Variation of soluble and insoluble calcium in red rains related to dust sources and transport patterns from North Africa to northeastern Spain

[1] We use the chemical composition of African dust delivered by red rains at a rural site in northeastern Spain (Montseny, 4146 0 N, 221 0 E) to describe its relationship with the possible provenance areas and the processes occurring during transport. To this end, we obtained the red rain insoluble composition for the major elements (Al, Fe, Ca, Mg, K, P, Ti, and Na) in 30 filters, the 210 Pb concentration in 23 filters, and the soluble cation concentrations (Na, K, Ca, and Mg) in 28 coincident red rain samples. These samples comprised most major events occurring at the site from 1983 to 2002. On the basis of back trajectories and satellite images, a distinction has been made between an eastern and western air mass flux with respect to 0 Greenwich for the analyzed samples. Principal component and ANOVA analyses between the two provenance groups have shown striking differences in the insoluble phase, with eastern samples being significantly richer in insoluble Ca, Mg, and Sr compared to western samples. Conversely, western samples had significantly higher concentrations of insoluble Al, Fe, K, V, and 210 Pb than eastern samples. Therefore, in the insoluble phase, the ratios of various elements to Ca were significantly higher in western provenances. However, these differences disappeared when considering bulk Ca ratios (bulk Ca = insoluble + soluble Ca). Neither of the ratios Fe/Al and Ti/Fe showed significant differences. This lack of differences is interpreted in view of a similar carbonated lithology broadly underlying both areas. The difference in insoluble Ca with respect to total Ca between provenances (Cainsoluble/ Catotal = 0.10 and 0.70 for western and eastern trajectories, respectively) is interpreted as a difference in calcite dissolution during transport. Evidence from 210 Pb data and from the length of the back trajectories indicates that western trajectories covered a longer distance than the eastern ones; their higher soluble Ca could be due to (1) higher calcite dissolution due to longer contact with wet fronts from the Atlantic and (2) particle segregation during transport, with finer (carbonate) particles more prone to dissolution due to a higher surface to volume ratio.

Ambrosia L. in Catalonia (NE Spain): expansion and aerobiology of a new bioinvader

This paper aims to determine the stage of the naturalization of ragweed (Ambrosia L.) in Catalonia, north-east Spain, and to analyze the airborne pollen pattern and provenance, in order to contribute to a better management of it and prevent the expansion of a possible new bioinvader that can also become a health problem due to its highly allergenic pollen. Biogeographical sampling consisted on the monitoring of Ambrosia populations through the territory over a 2-year period (2010–2011). Aerobiological sampling was based on the analysis of pollen records at eight aerobiological sampling stations, during the period 1994–2010. Pollen provenance sampling was examined using backward atmospheric air masses trajectories and synoptic maps, as well as through the application of a source-receptor model. Ambrosia colonies are expanding throughout the territory at a mean growing rate of 324% for the sampled territory. The Annual Pollen Indices appear to be clearly influenced by the pollen concentrations in the peak dates, and these are linked to long-range transport of pollen from regions where Ambrosia is widely widespread, such as eastern France, northern Italy and Hungary and Serbia. The episodes of pollen transport are increasing in number. Although airborne Ambrosia pollen type is not showing any clear increasing trend for the period under study, local populations of the plant could be having an influence on the pollen records, since the genus is clearly expanding in the territory at considerably high spread rates. Ambrosia populations have to be surveyed both for public health reasons and as a new bioinvader.

Moroccan Source Areas of the Painted Lady Butterfly Vanessa cardui (Nymphalidae: Nymphalinae) Migrating into Europe in Spring

ABSTRACT. Each spring, Vanessa cardui (Linnaeus) migrates into Europe, sometimes in huge numbers. Although it is widely accepted that migrants come from North Africa, there is currently a dearth of information on the source areas they originate from. However, in a recent study, a strong association between V. cardui arriving in spring in Catalonia (NE Spain) and synoptic-scale winds originating in North Africa was found, which allowed us to predict the most likely location for the source areas in the Maghreb. In March 2009 we organized an expedition to confirm in situ the occurrence of immature stages and/or emerging adults at one of the hypothetical breeding areas in Morocco. Immatures were found at virtually all the sampled sites, with the maximum abundance being recorded in the Souss valley. Breeding habitats with plenty of thistles and mallows were sufficiently common to permit populations of great density to build up. We found a massive emergence site of 1.8 ha with an estimated population of 170,000 larvae, of which 155,000 had successfully pupated, the rest having been parasitised by the wasp Cotesia vanessae. Bird predation of adults was also recorded at this site. Our observations, together with the typical patchy distribution of the ruderal habitats used for breeding, suggest that source populations most frequently originate in small habitat pockets with favourable conditions that allow for high patch occupancy and levels of oviposition.

Is long range transport of pollen in the NW Mediterranean basin influenced by Northern Hemisphere teleconnection patterns

Climatic oscillations triggered by the atmospheric modes of the Northern Hemisphere teleconnection patterns have an important influence on the atmospheric circulation at synoptic scale in Western Mediterranean Basin. Simultaneously, this climate variability could affect a variety of ecological processes. This work provides a first assessment of the effect of North Atlantic Oscillation (NAO), Arctic Oscillation (AO) and Western Mediterranean Oscillation (WeMO) on the atmospheric long-range pollen transport episodes in the North-Eastern Iberian Peninsula for the period 1994-2011. Alnus, Ambrosia, Betula, Corylus and Fagus have been selected as allergenic pollen taxa with potential long-range transport associated to the Northern Hemisphere teleconnection patterns in the Western Mediterranean Basin. The results showed an increase of long range pollen transport episodes of: (1) Alnus, Corylus and Fagus from Western and Central Europe during the negative phase of annual NAO and AO; (2) Ambrosia, Betula and Fagus from Europe during the negative phase of winter WeMO; (3) Corylus and Fagus from Mediterranean area during the positive phase of the annual AO; and (4) Ambrosia from France and Northern Europe during the positive phase of winter WeMO. Conversely, the positive phase of annual NAO and AO are linked with the regional transport of Alnus, Betula and Corylus from Western Iberian Peninsula. The positive phase of annual WeMO was also positively correlated with regional transport of Corylus from this area.

The role of temperature in tropospheric ozone

After evaluating some meteorological simulations, we detect an error of over 5°C in surface temperature. In order to assess the effect of this anomaly in temperature, we perform new simulations of an emission model and a photochemical model using the correct surface temperature in the meteorological data. Our goal is not to solve the problem in surface temperature estimates, but to reveal how it affects the air quality model. Our results show an increase in some maximum daily ozone levels, but they do not reveal any important change in the global pattern of ozone concentrations.