25th International Meeting on Organic Geochemistry IMOG 2011

P-392
Environmental forensic study of a complexly contaminated soil
at a former chemical plant
José Luis R. Gallego 1 , Michael A. Kruge 2 , Iván Lores 1 , Azucena Lara 1 , Carlos Sierra 1
1 Environmental Biotechnology and Geochemistry Group, Campus de Mieres, University of Oviedo., 33600 -
Mieres (Asturias), Spain, 2 Department of Earth and Environmental Studies, Montclair State University,
Montclair, NJ 07043, United States of America (corresponding author:jgallego@uniovi.es)
A detailed environmental forensic study of a former
chemical plant (Asturias, Northern Spain) was
performed to establish a relationship of spills and
other pollution events to the present state of its soil
and surficial water. The investigation employed a
three step process: First, we acquired general data on
the hydrological, soil, and geological conditions of the
site. Then we completed a comprehensive search for
information about the industrial activities performed in
the abandoned plant. Finally, the application of
molecular techniques and a forensic interpretation
permitted a detailed view of the different contaminants
affecting the site and their linkage with the former
industrial activity. Identification of pollutants and
evaluation of weathering was performed by different
applications of GC-MS techniques [1], whereas a
detailed study on the origin of the predominant ones
(PAHs) was carried out using Pyrolysis-GC/MS [2].
The study site comprises about 2.5 ha and had been
completely cleared of buildings then abandoned
before this study started. A typical soil column in the
affected area has a highly polluted sandy surface
layer averaging about 50 cm thick with interbedded
pebble layers in which infiltrating water accumulated.
From 50 cm to 4 m deep there are compact, nonpermeable
carbonate and clay strata, which contain
most of the contamination in the top two meters. The
water table is below 5 m, in a more permeable
alluvium layer. An extensive compilation of historical
data (personal interviews, legal registers, etc.) yielded
a comprehensive list of processes and activities at the
plant likely to have produced contamination,
summarized as follows:
a) As the principal activity at the site during the 1970's
and 1980's, two separate units produced
naphthalene, phenol, and other compounds from coal
tar.
b) Another unit of production was dedicated to the
manufacture of resins. A considerable amount of
other chemical products (pesticides, solvents, etc.)
was stored, although probably not manufactured, in
the plant.
c) In the 1990‘s the plant was closed and then used
for years to store chemical waste, particularly
polychlorinated biphenyls, coolants and other
unspecified products.
As a main result of the forensic study we were able to
divide the area affected in several subareas. In all of
them, PAHs (mostly of combustion origin), and
specifically naphthalene, were the most abundant
contaminants in GC-MS determinations, while indene
was also remarkably abundant in soil pyrolyzates. We
also found areas for which hydrocarbon fingerprinting
indicated fuel spills (petrogenic origin, associated with
old heating systems). Additionally, evidence of animal
fats was detected and this was linked to the former
storage of ‗Tinol‘, a residue from steel plants,
composed of a mixture of animal fats, mineral
lubricants and chips (Fe oxides mainly). Many other
contaminants were detected and classified (Table 1).
The conclusions obtained were useful to select
strategies for site remediation.
Comp Possible sources Comments
PAHs
Coal tar processing
Fuel spills
Predominance of
parent PAHs
Aliphatics Fuel and diesel spills Slightly weathered
Phenols Coal tar processing Predominant in water
Phthalates Resins manufacture DEHP predominance
Chlorinated
Waste and solvent
storage
CAHs and PCBs in
low concentrations
Fats ‗Tinol‘ storage Oleic acid and others
Table 1: Main contaminants and sources found.
[1] Gallego, J.R. et al. (2010) Organic Geochemistry
41, 896-900.
[2] Kruge, M., Permanyer, A. (2004) Organic
Geochemistry 35, 1395-1408.
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