Potentially toxic elements capture by an active living wall in indoor environments: Effect of species in air phytoremediation.

Indoor air pollution is a serious health problem throughout the world. Plants are known to be able to reduce the effect of air pollution and improve indoor air quality (IAQ). The aim of the present study was to compare the effectiveness of four plant species (Tradescantia zebrina hort. ex Bosse, Philodendron scandens K. Koch & Sello, Ficus pumila L. and Chlorophtytum comosum (Thunb.) Jacques) planted in an active living wall (ALW) for capturing particle pollutants. The ALW was introduced in a glass chamber and exposed to large (10-40 µm) and fine (1.2-10 µm) airborne particles containing a fixed concentration of potentially toxic elements (Al, B, Cd, Co, Cr, Cu, Ni and Pb). The surface particle deposition (sPM) was estimated in the leaves from the four species and the potentially toxic element concentration in the particulate matter (PM) was measured in plants, medium culture and in the ALW support system. The distribution of different particle size fractions differed between species. The capacity to trap particles on leaf surfaces was similar among the species (4.7-13 ng cm-2) except when comparing Tradescantia and Chlorophytum with Ficus, being higher in the latter species. Differences in toxic elements accumulation capacity were observed between species depending on the elements considered. The percentage of reduction in indoor pollution using an ALW was in a range of 65-79% being similar between species. Plants were the most important component of the ALW in terms of accumulation of indoor potentially toxic elements. The data presented here could be used to model the effectiveness of ALW systems schemes in improving IAQ.

Determination of soluble ultra-trace metals and metalloids in rainwater and atmospheric deposition fluxes: a 2-year survey and assessment.

The present work investigates the relationships between composition of rainwater and dry deposition fluxes by trace metals and metalloids. A modification in automatic "wet-only" and "dry-only" samplers was applied, which allowed the collection and conservation of samples separately. ICP-MS technique was used for the determination of analytes in samples. Concentrations of soluble elements in rainwater were measured directly in filtered samples. A sequential acid treatment with nitric, hydrofluoric and finally perchloric acids was used to measure the total contents of metals and metalloids in coarse particles. Variation between periods of heavy and light rains was assessed. Almost all of the metals and metalloids - B, Tl, Th, U, Al, Cs, Be, Ti and others - studied in dry deposition showed important decreases in concentrations (40-92%) during periods of heavy rainfall. Most of these metals and metalloids - As, Cr, Co, Ni - presented their highest levels (53-90%) in heavy rainfall periods in rainwater samples. Sources were identified in both types of samples collected using a new chemometric tool (SPCA). Urban traffic, surrounding contaminated soils and local anthropogenic sources were identified for rainwater samples. Natural and contaminated soils and general anthropogenic emissions were the sources identified for dry deposition fluxes.

The composition and relationships between trace element levels in inhalable atmospheric particles (PM10) and in leaves of Nerium oleander L. and Lantana camara L.

In order to evaluate the composition of inhalable atmospheric particles and to study the relationship between trace element levels in PM10 and in leaves of two plant species, the amount of Ba, Cu, Fe, Mn, Pb, Ti and V were analysed in PM10 and in Nerium oleander L. and Lantana camara L. leaves from two sites in the city of Seville and one remote control site. In PM10, the Cu and Fe content was significantly lower (p<0.05) in the control site than in the other sites. No correlations between leaf content and air content were found for the elements in L. camara. On the contrary, positive and significant correlations (p<0.05) were found between leaf content of N. oleander and PM10 content for Cu and Fe. The data suggest that N. oleander can be used in atmospheric biomonitoring studies, because it is especially useful for Cu and Fe, N. oleander being a better indicator than L. camara.

Particle-size distribution of polycyclic aromatic hydrocarbons in urban air in southern Spain.

The size distribution of polycyclic aromatic hydrocarbons (PAH) was determined for airborne particles from a large city with high vehicular traffic. The analytical method was optimised and validated using NIST standard reference material (SRM 1649a Urban Dust). The 16 priority PAH listed in the US-EPA were Soxhlet-extracted from filtered particulate matter and then fractionated using on-column chromatography. The aromatic fraction was quantified by gas chromatography-mass spectrometry. Real samples of particles collected in Seville (Spain) were analysed using the validated method. Values for the total concentration of PAH in the air, as well as the concentrations of each PAH in six particle-size ranges were obtained. Values of the PAH in TSP, PM10, PM2.5 and PM1 were assessed.

Study of traffic pollution by metals in Seville (Spain) by physical and chemical speciation methods.

Eighty-three samples of atmospheric particles were collected at a representative traffic site in the Mediterranean city of Seville during a period of one year. Urban particles were collected on quartz filters with a high-volume sampler coupled with a cascade impactor which separates particles into six size ranges: >10, 10-4.9, 4.9-2.7, 2.7-1.3, 1.3-0.6, and <0.6 microm. The total metal content, its distribution by size (physical speciation), and the concentrations of different chemical forms (chemical speciation) in particles less than 0.6 microm were determined. The chemical speciation scheme furnished four fractions: soluble and exchangeable metals; carbonates, oxides, and reducible metals; oxidisable and sulfidic metals bound to organic matter; and residual metals. The samples were analysed by ICP-OES for Pb, Ni, Cd, S, Fe, Zn, Cu, Ba, Mn, and V. Gaseous pollutants, traffic intensities, and primary meteorological data provided by the atmospheric and traffic networks were statistically related to the analytical data. Analytical and statistical results from physical and chemical speciation singled out Ba as a valid tracer of vehicular traffic, instead of Pb, in cities with high traffic density. Another important relationship was found between Pb and Cu. Physical speciation of lead showed that the major risk for health was from fine particles less than 2.7 microm, because particles between 2.7 and 0.6 microm were the size fractions of the total suspended particles with the major mass abundance of lead (mainly particles between 2.7 and 1.3 microm) and because particles less than 0.6 microm were the fraction of airborne particles most abundant in the urban air. Chemical speciation results showed that special attention must be taken with Ni and Cd concentrations, because of their high potential bioavailability, mainly a result of the high solubility of the chemical forms of Ni in the finest particles.