INVESTIGADORES
AVILA Eldo Edgardo
congresos y reuniones científicas
Título:
Chemical Composition of Rainwater in Córdoba City, Argentina
Autor/es:
LOPEZ M.L.; M. L. ASAR; CEPPI S.; BÜRGESSER R.; AVILA E. E.
Reunión:
Congreso; American Geophysical Union, Meeting of the Americas; 2013
Resumen:
Sampling and chemical analysis of rainwater has proved to be a useful technique for
studying its chemical composition and provides a greater understanding of local and regional dispersion of
pollutants and their potential impacts to ecosystems through deposition processes.
Samples of rainwater were collected during 2009-2012, in Córdoba city, Argentina. Two kind of sampling
were performed: event-specific and sequential. The objective of the first of these was to determine the
chemical concentration of the total rain, while the objective of the second one was to analyze the variability
of the chemical concentration during an individual rain event.
The total volume of each sample was divided in halves. One half was filtered through 0.45 μm membrane
filter. After this, all the samples were reduced by evaporation to a final volume of 10 ml. The non-filtered
samples were acidified and digested in accordance to the method 3050B of the Environmental Protection
Agency (EPA) for acid digestion of sediments. Multi-elemental standard solutions in different concentrations
were prepared by adequate dilutions. Gallium was added as an internal standard in all standard solutions
and samples. Exactly 5 μL of these solutions were deposited on acrylic supports. When these droplets
were dried, Synchrotron Radiation Total Reflection X-Ray Fluorescence technique was used for
determining the chemical elements. Spectra were analyzed with the AXIL package for spectrum analysis.
Due to the intrinsic characteristics of the total reflection technique, the background of the measurements is
significantly reduced and there are no matrix effects, therefore quantification can be obtained from the linear correlation between fluorescence intensity and the concentration of the element of interest. The
elements quantified were S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, and Pb. For all of
them a calibration curve was performed in order to quantify their concentrations on the samples.
The results show that the average pH in city rainwater was pH=6.5; the elements found in the samples
were S, Ca, Cu, Cr, Sr, P, Fe, Mn, Pb, K, Ti, V, Zn and the average concentrations of these elements were
below the limits established by World Health Organization for drinking water, and show a high natural
variability.
The temporal evolution of inorganic ion concentration during rain events was analyzed and the scavenging
coefficients were calculated and compared with data from literature. A comparison was made between the
rainwater chemical composition and chemical composition in the aerosols scavenging during the rain.
This study is the first in Córdoba city to analyze the chemical composition of rainwater and constitute a
base for future comparison of variability in pH and elemental composition.