INDOOR/OUTDOOR CHARACTERIZATION OF ISOTOPIC RATIOS OF
LEAD IN AN ATMOSPHERE-POLLUTED AREA OF CHIHUAHUA CITY,
MEXICO
Area: Quimica Ambiental, Tema: 1. Quimica de la atmosfera, Oral (
) Cartel ( X )
Marcos Delgado Ríos1,a, Jorge Gardea-Torresdey2, Jason Parsons2, Kenneth M.
Dokken2, José R. Peralta-Videa2, Martha Laura Fernández2, Gustavo Cruz Jiménez3,
Alma Cota Espericueta1
aResponsable,
e-mail: marcos.delgado@gmail.com, Tel. y Fax: (656) 613-8968
Autónoma de Cd. Juárez, Instituto de Ciencias Biomédicas
2 University of Texas at El Paso, Department of Chemistry
3 Universidad de Guanajuato, Facultad de Química
1 Universidad
Introduction. Lead (Pb) is a hazardous
element present in the surrounding
environment in numerous chemical and
physical varieties. One form that is
significant is their presence as different
isotopes. Since Pb has many possible
supplies and toxic pathways, isotopic ratios
are an excellent way to survey Pb sources
in atmospheric samples (Mukai et al.,
2001).
Objective. To determine the isotopic ratios
of Pb206 and Pb207 in the indoor and outdoor
samples to determine if the source of the
pollution is from anthropogenic and/or
natural sources.
Methodology. Particulate matter less than
10 micrometers (PM10), lead (Pb), arsenic
(As), and Pb isotopes were measured in the
atmosphere of some indoor/outdoor (I/O)
households selected in the 2 km-radius
area of study. A high-volume apparatus
was used for outdoor screening and lowvolume equipment was used for indoor air
screening. The study was conducted for 14
days (24 hours sampling) using Whatman
glass fiber filters as a supporting medium.
At the end of the study period, a small
amount of each filter (a 1” X 8” piece) from
every filter of the outdoor sampling and the
entire glass filters from the indoor sampling
were digested using EPA IO-3.4 procedure
and analyzed using inductively coupled
plasma optical emission spectrometer (ICPOES). 206Pb and 207Pb isotopes were
analyzed with the ICP-mass spectrometry
(ICP-MS), determining their concentration
and their 206Pb/207Pb ratio to know the
predominant source of the Pb in the
geographical area of interest. ANOVA and
t-test were used to discern the levels of Pb
in the airborne particulate matter (As
measurements revealed levels below the
detection limit of the ICP-OES).
Results and conclusions. The results are
similar to other studies showing that the
most important sources for PM10 and Pb
entries is the external dust (Martinez et al.,
2004). Both indoor and outdoor individual
PM10 samples were below the permissible
limits. Pb isotopic rates were similar to the
mean ratio detailed in cities such as Mexico
City but different than county environments
proving that the resuspension of dust
contaminated before with anthropogenic
activities is one of the main sources for
airborne Pb.
Acknowledgements. We acknowledge the
financial support of the University of Texas
at El Paso’s Center for Environmental
Resource
Management
(CERM),
CONACyT (Consejo Nacional de Ciencia y
Tecnología of Mexico) Grant # 150290, and
the Government of the State of Chihuahua.
Also, we would like to thank my friends of
the Environmental Engineering Department
at Centro de Investigación en Materiales
Avanzados, S. en C. (CIMAV) for the
logistical and technical support.
References.
Martínez, T., Lartigue, J., Juárez, F., ÁvilaPerez, P., Zarazua, G., Márquez, C., Orta, M. P.,
Álvarez, V. (2004). Application of Lead isotopic
ratios in atmospheric pollution studies in the
Valley of México. J. of Atmospheric Chemistry,
49:415-424.
Mukai, H., Machida, T., Tanaka, A., Vera, Y. P.,
Uematsu, M. (2001). Lead isotope ratios in the
urban air of eastern and central Russia.
Atmospheric Environment, 35:2783-2793