Toxic metals from atmospheric particulate matter in food species of tomato (Solanum lycopersicum) and strawberry (Fragaria x ananassa) used in urban gardening. A closed chamber study.

In this work, two plant foods, strawberry and tomato, were subjected to exposure to metals from synthetic airborne particles in a closed chamber experiment. The synthetic particles were obtained in the laboratory. Within the closed chamber, particles were added and recirculated for 4 days in a turbulent air stream, causing deposition on the different parts of the plants. They were evaluated because of their increasingly frequent cultivation in urban gardens of cities. The main objectives were to determine whether the species accumulate metals significantly, which species accumulate the most, and in which parts of the plant. Finally, an attempt was made to differentiate the accumulation of pollutants by surface deposition on leaves and fruits from the adsorbed metals into the leaf or the fruit by their stomata or cuticles. The concentration of heavy metals was quantified in fruits, leaves and the soil after exposure. Metals were evaluated as a whole and individually, both in dry and fresh weight basis. The decrease of particulate matter and metals in the air inside the chamber was also studied in order to evaluate the use of both food species as air purifier by vertical gardens. The concentration of metals in plants (mg kg-1) and airborne particles (mg m-3) was measured by microwave plasma optical emission spectroscopy (MP-AES). For the sake comparison of total amount of metals in the samples concentrations were normalized. Strawberries was the food species that accumulated the largest amount of metals. In a dry weight basis, tomato leaves and strawberry fruits were the parts of the plants with higher accumulation capacity of particles and metals. The potential toxic elements Cd, Ni and Cr in tomato leaves and in strawberry fruits had a higher presence in the interior of the plant system. In a fresh weight basis, the strawberry fruit had the most accumulation capacity for metals.

A rapid Soxhlet and mini-SPE method for analysis of polycyclic aromatic hydrocarbons in atmospheric particles.

An analytical method was validated with two reference materials of polycyclic aromatic hydrocarbons in atmospheric particles. Standard reference materials (SRMs) were incorporated into the matrix of unexposed cut quartz filters. The methodology was previously designed and extraction of polycyclic aromatic hydrocarbons (PAHs) from fortified filters was based on a rapid low-cost method, for a low consumption of volume and time. The optimisation combined a low-volume Soxhlet apparatus used in hot Soxhlet mode with a quick clean-up by solid-phase extraction with special cartridges. The quantification of target compounds was performed by gas chromatography/mass spectroscopy in SIM mode. Temperatures of injector and oven program of the GC-MS were also optimised. Experimental variables of both systems were successfully optimised and validated, achieving a robust analytical methodology.

Assessment of the sequential principal component analysis chemometric tool to identify the soluble atmospheric pollutants in rainwater.

In this study a new method of principal component (PC) analysis, sequential PC analysis (SPCA), is proposed and assessed on real samples. The aim was to identify the atmospheric emission sources of soluble compounds in rainwater samples, and the sample collection was performed with an automatic sampler. Anions and cations were separated and quantified by ion chromatography, whereas trace metals and metalloids were determined by inductively coupled plasma mass spectrometry. SPCA results showed eight interfering PCs and ten significant PCs. The interfering cases originated from different atmospheric sources, such as resuspended crustal particles, marine aerosols, urban traffic and a fertilizer factory. The significant PCs explained 84.6% of the total variance; 28.1% accounted for the main contribution, which was resuspended industrial soil from a fertilizer factory containing NO(2)(-), NH(4)(+), NO(3)(-), SO(4)(2-), F(-), Al, K(+), Mn, Sb and Ca(2+) as indicators of the fertilizer factory. Another important source (15.0%) was found for Na(+), Mg(2+), K(+), Cl(-) and SO(4)(2-) , which represents the marine influence from south and southwest directions. Emissions of Ba(2+), Pb, Sr(2+), Sb and Mo, which represent a traffic source deposited in soils, were identified as another abundant contribution (12.1%) to the rainwater composition. Other important contributions to the rainwater samples that were identified through SPCA included the following: different urban emissions (Cu, As, Cd, Zn, Mo and Co, 18.1%), emissions from vegetation (HCOO(-), 7.7%) and emissions from industrial combustion processes (Ni, V 15.6%). The application of SPCA proved to be a useful tool to identify the complete information on rainwater samples as indicators of urban air pollution in a city influenced mainly by vehicle traffic emissions and resuspended polluted soils.