Silvia Alonso-Pérez

Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

An analysis of chemical composition data of particulate matter samples (TSP, PM 10 and PM2.5) collected from 2002 to 2008 in the North Atlantic free troposphere at the Izãna Global Atmospheric Watch (GAW) observatory (Tenerife, Canary Islands) shows that desert dust is very frequently mixed with particulate pollutants in the Saharan Air Layer (SAL). The study of this data set with Median Concentrations At Receptor (MCAR) plots allowed the identification of the potential source regions of the dust and particulate pollutants. Areas located at the south of the southern slope of the Atlas mountains emerge as the most frequent source of the soil desert dust advected to the northern edge of the SAL in summer. Industrial emissions occurring in Northern Algeria, Eastern Algeria, Tunisia and the Atlantic coast of Morocco appear as the most important source of the nitrate, ammonium and a fraction of sulphate (at least 60 % of the sulphate<10 μm transported from some regions) observed in the SAL. These emissions are mostly linked to crude oil refineries, phosphate-based fertilizer industry and power plants. Although desert dust emissions appear as the most frequent source of the phosphorous observed in the SAL, high P concentrations are observed when the SAL is affected by emissions from open mines of phosphate and phosphate based fertilizer industry. The results also show that a significant fraction of the sulphate (up to 90 % of sulphate <10 μm transported from some regions) observed in the SAL may be influenced by soil emissions of evaporite minerals in well defined regions where dry saline lakes (chotts) are present. These interpretations of the MCAR plots are consistent with the results obtained with the Positive Matrix Factorization Correspondence to: S. Rodŕıguez (srodriguezg@aemet.es) (PMF2) receptor modelling. The results of this study show that North African industrial pollutants may be mixed with desert dust and exported to the North Atlantic in the Saharan Air Layer.

Changes in the Mediterranean pine forest: pollination patterns and annual trends of airborne pollen

In some areas, forests are being affected in diverse aspects such as structure, composition and biodiversity showing an increase or a decrease in the growth rates. Pinus is one of the most dominant genera in the forests of the Northern Hemisphere. This study analyzes the pine pollination patterns in 30 locations of Spain with an average of 21-year dataset. The aim is to evaluate possible changes in flowering intensity as well as in annual pollen production trends, according to the airborne pollen patterns. Annual Pollen Indices show three threshold values: (1) over 4000 grains per year in Catalonia, the Central System Mountains and Ourense (Galicia), (2) between 4000 and 1000 grains in central-south Spain and in the Balearic Islands, and (3) under 1000 in eastern Spain, Cartagena and the Canary Islands. Airborne pollen patterns were also influenced by Pinus species: The species located in the littoral and low land areas pollinated in the first pollination phase, from February to April, and the mountain pine species did in the second one, from April to June. The statistical analyses reveal increasing significant trends in 12 sites and significant decreasing trends in two. The Pinus flowering intensity is showing an earlier start and a delay in the end of the pollination period, thus a longer period of pollen in the air. This study suggests that the aerobiological monitoring is an interesting bio-indicator of changes happening in Pinus landscapes, and therefore explains the vulnerability of this genus in Spain.

Saharan dust-induced chlorophyll blooms in the northwest African upwelling

During the period 2000-2005, the atmospheric dynamic showed a significant influence on the dust inputs dynamic and, as a result, on the primary production of the northwest African Upwelling System since 2000 to 2005. In this period, the annual mean sea level pressure became higher, ranging from 1014 to 1015 mb. Mean annual zonal wind intensity became higher (from 1.1 to 1.8 m s-1), while the mean annual meridional wind reduced from 6.2 to 5.3 m s-1. Mean annual satellite-derived AVHRR/NOAA Sea Surface Temperature recorded in the northwest African Upwelling becomes warmer with 18.3°C to 18.8°C in Cape Ghir, and from 19.5°C to 20.3°C north Canary Islands waters. Chlorophyll data from SeaWiFS/OV-2 showed a different pattern trend. Mean annual CHL levels increased at eutrophic-like waters of Cape Ghir from 0.65 mg m-3 to 0.9 mg m-. However, data were significantly reduced from 0.59 mg m-3 to 0.31 mg m-3 in oligotrophic-like waters of the Canary Islands. Changes observed in the role of CHL during the last 6-years period could be associated to intensive dust deposition and the exceptional weather warming observed in this area since 2000. However, it is addressed to a single 7 years period and conclusions on possible links between dust deposition and marine biochemistry activity cannot be generalized.