Geoderma 136 (2006) 20 – 27
www.elsevier.com/locate/geoderma
PAHs and trace elements in volcanic urban and natural soils
Giulia Maisto a,⁎, Flavia De Nicola a , Paola Iovieno c , Maria Vittoria Prati b ,
Anna Alfani c
a
Dipartimento di Biologia Strutturale e Funzionale, Università degli Studi di Napoli Federico II,
Complesso Universitario di Monte Sant'Angelo, via Cinthia, 80126 Napoli, Italy
b
Istituto Motori del CNR, via Marconi 8, 80125 Napoli, Italy
c
Dipartimento di Chimica, Università di Salerno, via S. Allende, 84081 Baronissi (SA), Italy
Received 23 December 2004; received in revised form 16 December 2005; accepted 19 January 2006
Available online 3 March 2006
Abstract
Surface volcanic soils (0–5 cm) were analysed for 8 trace elements (Cd, Cr, Cu, Fe, Mn, Pb, V, Zn) and 27 PAHs. Soils were
collected every four months at five urban sites in Naples and at a control site in the Vesuvius National Park from May 2001 to May
2002. Cr, V and Fe were more abundant in the control soils while Pb, Zn and ΣPAH were higher in the urban soils. Pb was 2–4 and
ΣPAH 2–20 fold higher in urban than in control soil, whereas V was 2 fold higher in the control than in urban soils. Among the
urban soils, both trace element and PAH accumulations also differed. Atmospheric deposition is responsible for trace element and
PAH accumulation in urban soils. Phenanthrene, fluoranthene, pyrene, benzo[a]pyrene, benzo[b+k+j]fluoranthene and benzo[g,h,i]
perylene were the most abundant PAHs both in control and urban soils. Naphthalene was also high in the control soil. Coronene
was the most abundant at the urban site near the highway. The accumulation of PAHs in soils appeared to be affected by soil
organic matter and microbial metabolism.
© 2006 Elsevier B.V. All rights reserved.
Keywords: Trace elements; PAHs; Soil accumulation; PAH profiles; Naples
1. Introduction
Soils may be affected by deposition of various kinds
of air pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and trace elements (Adriano, 1986; Alfani
et al., 1996; Sheu et al., 1997; Maisto et al., 2004a).
PAHs derive from combustion processes both of natural
and anthropogenic origin; trace elements are emitted,
conspicuously, by human activities. The magnitude of
⁎ Corresponding author. Tel.: +39 081 679095; fax: +39 081
679233.
E-mail address: g.maisto@unina.it (G. Maisto).
0016-7061/$ - see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.geoderma.2006.01.009
the contamination depends on different parameters such
as air pollutant concentrations, prevailing atmospheric
conditions and size distributions of the particulate fraction (Baek et al., 1991). Soil concentrations of trace
elements and PAHs result from the integration of air
contamination over long-term exposure (Maisto et al.,
2003, 2004b). However, litterfall, soil microbial
activities and soil texture may also affect the accumulation of both trace elements and PAHs in surface soils
(Kabata-Pendias and Pendias, 1992; Tuháćková et al.,
2001).
Our research aimed to detect the concentrations
of some trace elements and PAHs in urban and control
21
G. Maisto et al. / Geoderma 136 (2006) 20–27
2001) and the microbial biomass C, by substrate-induced
respiration method (Sparling, 1995), were also determined in triplicate, measuring the CO2 evolution rate
in non-amended and glucose-amended samples by
gas chromatography, after 4 h of incubation at 25 °C
in darkness. Microbial biomass C (μg C g− 1 d.w. soil)
was calculated as 50.4 × glucose respiration rate (μl
CO2 g− 1 d.w. soil h− 1).
soils in order to evaluate how air pollutant deposition
influences the level of the investigated compounds. The
relationship between soil organic matter, microbial activity and PAH accumulation was also investigated.
2. Materials and methods
Samplings of surface soils (0–5 cm) were carried
out, after litter removal, at five urban sites in Naples
(U1–U5), and at a control site in woodland in the
Vesuvius National Park (C), 12 km from Naples at about
750 m a.s.l. The sampled soils originated from pyroclastic materials coming from various Vesuvius eruptions (Di Gennaro, 2002; De Nicola et al., 2003). The
sites are characterised by a typical Mediterranean climate. The urban sites, located in downtown Naples, are
affected by high traffic flow and differ greatly in some
characteristics: two of them have soft soils and are rich in
organic matter with dense, extensive grass cover and
abundant litter (U2 and U5), one with a non-mature soil
profile is covered by lawns and has no litter, since it was
periodically removed (U1), and two have compact soils,
little grass cover and scant litter (U3 and U4). However,
all the soils have volcanic origins insofar as they were
imported from the Vesuvius area. Soil samples were
collected at the base of the same plant species (Quercus
ilex L.) in order to minimize the effect of vegetation upon
soil characteristics. Soils were sampled at the stem flow
microsites to enhance the effect of air depositions. The
samplings were carried out from May 2001 to May 2002
every four months. At each site the soils were sampled,
from the base of at least 8 specimens, through a PVC
cylinder and a Plexiglas trowel in order to avoid the
introduction of metal contamination. In the laboratory,
the soil sub-samples collected at each site were mixed
to obtain a homogeneous sample and sieved (2 mm).
Organic matter contents by loss on ignition, pH by electrometric method in a water suspension (1 : 2.5 = soil :
water), water contents by weighing before and after oven
drying at 105 °C were all measured in the collected
soils in triplicate. The basal respiration (Schipper et al.,
2.1. Detection of PAH concentrations
Air-dried soil samples (ca. 30 g wet weight) were
mixed with equal quantities of sodium sulphate anhydrous. A mix of deuterated PAHs (naphthalene D8,
acenaphthene D10, phenanthrene D10, chrysene D10
and perylene D12) was added before extraction for
quantification. The samples were extracted in a mixture
of dichloromethane : acetone (1 : 1 = v : v) by 3 consecutive sonications (Misonix, XL2020). After the first
sonication (3 min) in 100 ml of solvent mixture, the
samples were recovered by vacuum filtration and the
extracts were stored in a flask. The recovered samples
were sonicated (3 min) again, adding 100 ml of solvent
mixture, and consecutively a third sonication (3 min)
was carried out adding another 100 ml of the solvent
mixture. After the third sonication, the samples were
vacuum filtered and the extracts were added to the extracts from the first sonication. The extracts were rotary
evaporated to ca. 5 ml, filtered (0.2 μm), and completely
dried under a gentle nitrogen stream. Subsequently, they
were diluted with 4 ml of dichloromethane to be
analysed. We developed our method using EPA 3550c
as a starting point (Index to EPA test methods, 2003).
The analyses were carried out by GC-MS (Hewlett
Packard 5890 GC with on-column manual injection,
coupled to a Hewlett Packard 5971 mass-selective
detector, and equipped with an HP-5MS capillary column 30 m × 0.25 mm i.d. with a 0.25 μm film thickness
and a phase ratio of 250). Oven temperature program was
held at 33 °C for 1 min, then ramped at 20 °C min− 1
to 280 °C and held for 15 min. The on-column inlet
Table 1
Organic matter content (mg g− 1 d.w.), basal respiration (μg CO2 g− 1 d.w. h− 1), microbial biomass C (μg C g− 1 d.w.), pH, water content (mg g− 1 d.w.)
mean values (s.e.), in the control and urban soils over the investigated period
C
Organic matter
Basal respiration
Microbial biomass C
pH
Water content
a
287.7 (10.5)
35.77 (2.94)
2159 (185)
5.51 (0.26)
586.5 (111.4)
Data referred to September 2001.
U1
91.8 (7.9)
3.13 a
549 a
7.66 (0.17)
350.8 (39.1)
U2
261.9 (12.2)
32.52 a
1617 a
6.90 (0.13)
384.4 (59.4)
U3
80.6 (2.8)
12.19 a
1158 a
6.37 (0.16)
178.8 (24.4)
U4
76.3 (7.2)
8.02 a
875 a
6.16 (0.25)
120.5 (25.9)
U5
161.5 (6.4)
24.22 a
2198 a
5.90 (0.22)
304.0 (36.1)
22
G. Maisto et al. / Geoderma 136 (2006) 20–27
Table 2
Mean concentrations (s.e.) of Cd, Cr, Cu, Mn, Pb, V (μg g− 1 d.w.), Fe, Zn (mg g− 1 d.w.), and ΣPAHs (ng g− 1 d.w.) in the control and urban soils over
the investigated period
Cd
Cr
Cu
Fe
Mn
Pb
V
Zn
ΣPAHs
C
U1
U2
U3
U4
U5
0.42 (0.06)
47.84 (3.46)
64.45 (3.03)
41.65 (1.87)
950.00 (37.88)
52.16 (6.97)
223.41 (17.73)
103.50 (10.65)
264.84 (28.03)
0.31 (0.05)
29.95 (2.08)
44.04 (4.50)
34.19 (1.44)
1050.00 (31.18)
79.12 (8.06)
118.64 (7.24)
115.33 (5.33)
677.14 (45.99)
0.72 (0.08)
22.82 (2.00)
178.83 (12.11)
30.77 (1.37)
941.67 (39.97)
198.16 (18.50)
100.68 (4.09)
189.17 (7.39)
1462.94 (133.40)
0.52 (0.07)
45.55 (4.13)
104.94 (9.11)
38.65 (0.69)
983.33 (29.66)
136.69 (12.44)
142.64 (18.35)
197.67 (15.54)
5293.90 (988.06)
0.60 (0.03)
26.92 (3.14)
109.80 (7.93)
38.81 (1.43)
995.83 (35.60)
156.01 (13.66)
111.43 (15.94)
181.17 (7.76)
3576.08 (267.51)
0.64 (0.03)
15.82 (1.05)
46.77 (1.45)
28.52 (1.08)
887.50 (46.34)
222.10 (3.56)
81.92 (8.03)
220.83 (15.95)
874.42 (22.81)
temperature was set in oven track, with an injector
temperature 3 °C higher than the oven temperature at
all times. The carrier gas was helium (constant flow
rate: 1 ml min− 1). The SIM (selected ion monitoring)
modality of acquisition was used.
The 27 investigated PAHs were naphthalene (Nap),
acenaphthylene (Acy), acenaphthene (Ace), fluorene
(Fle), phenanthrene (Phe), anthracene (Ant), fluoran-
thene (Fla), pyrene (Pyr), 2,3-benzofluorene (BFle),
benzo[c]phenanthrene (BPhe), benzo[g,h,i]fluoranthene
(BghiF), benzo[b]nafto(1,2-d)tiophene (BnT), cyclopenta[c,d]pyrene (CpPyr), benzo[a]anthracene (BaA),
chrysene + triphenylene (CT), benzo[b+k+j]fluoranthene (BbkjF), benzo[e]pyrene (BeP), benzo[a]pyrene (BaP), 1,3,5-triphenylbenzene (TpB), perylene
(Per), indeno[1,2,3-c,d]pyrene (Ind), benzo[b]
Fig. 1. Boxplot of trace element and total PAH concentrations in the urban soils collected in May and September 2001, and in January and May 2002.
The box indicates the 25th and 75th percentiles, the continuous lines indicate the median values. The line represents concentrations in the control soil.
G. Maisto et al. / Geoderma 136 (2006) 20–27
chrysene ce:hsp sp="0.12"/>+ picene (BbCP), dibenzo
[a,c]anthracene (DacA), dibenzo[a,h]anthracene
(DahA), benzo[g,h,i]perylene (BghiP), anthanthrene
(Anth) and coronene (Cor). They were quantified after
a calibration curve had been performed for each PAH;
the analyses were carried out in triplicate. Concentrations of all the PAHs were calculated considering the
recovery of deuterated PAHs that ranged from 40% to
80%, with the highest losses for naphthalene and
acenaphthene. The ΣPAHs reported in this study represent the sum of the concentrations of all compounds.
The analytical detection limit was approximately 2 pg
μl− 1, for each analysed PAH.
2.2. Detection of trace element concentrations
The oven-dried (75 °C) soil samples were ground
into a fine powder by an agate pocket (Fritsch pulverisette) and 250 mg of each sample were mineralised
with the addition of 2 ml of HF (50%) and 4 ml of
HNO3 (65%) in a micro-wave oven (Milestone mls
1200, Microwave Laboratory Systems). Total concentrations of the elements were measured by atomic
absorption spectrometry (SpectrAA 20, Varian) via
graphite furnace (Cd, Cr, Cu, Pb and V) or via flame
(Fe, Mn and Zn). The analyses were carried out in
triplicate. Accuracy of the trace element measurements
was checked by concurrent analysis of standard reference materials from the Community Bureau of
Reference from the Commission of the European Communities (BCR No. 142R): recovery rates ranged from
86% to 98%.
23
Over the period studied, in the urban soils, for Cd,
Cu, Pb, Zn and ΣPAHs, higher values were generally
detected than in the control soil; by contrast, Cr, Fe and
V had lower values in the urban soils than in the control
soil. Mn exhibited similar values in urban and control
soils (Table 2).
At each sampling, there were differences in trace
element concentrations between control and urban soils
depending on each investigated element (Fig. 1). Cu and
Mn soil concentrations at the control site were in the
range of the values detected in the urban soils (Fig. 1),
although Cu concentrations in the control soil showed
values close to the lowest in the urban soils. Cr and V
concentrations were higher in the control than urban
soils, as was Fe with the exception of January (Fig. 1); Pb
and Zn were higher in the urban soils, as was Cd with the
exception of September (Fig. 1). The PAHs reflected the
same trend as Pb and Zn (Fig. 1), showing at each
sampling higher values in the urban than in the control
soils.
Among the urban soils large concentration differences were evident for Cd, Cr, Cu, Pb and Zn (Table 2).
Differences in ΣPAH concentrations were more substantial, with the highest values at sites U3 and U4 and
the lowest at sites U1 and U5 (Table 2).
At the control site, Cd, Cr, Mn, Pb and Zn concentrations showed similar trends over time with the
highest values in September (Fig. 1). At the urban sites
no similar trend was observed among sites or
contaminants.
The profiles of the detected PAHs were almost
the same in the control and urban soils as shown in
2.3. Statistical analyses
The data were processed by statistical tests. The
correlations between each element and ΣPAH concentrations in the soils as well as the correlations between
the investigated pollutants and the physico-chemical soil
characteristics were evaluated by Spearman's test, using
the SigmaStat package.
3. Results
Organic matter content and water content were
higher in the control than urban soils; by contrast, pH
was lower (Table 1). Among the urban soils, three sites
showed the lowest basal respiration and microbial
biomass, accordingly with the lowest values of soil
organic matter, while at the other two sites basal
respiration and microbial biomass showed values close
to the control site.
Fig. 2. Percentages of each PAH over the total in urban soils (U1–U5)
and in the control soil (C) at the January 2002 sampling. The trend of
the profiles was repetitive among the samplings.
24
G. Maisto et al. / Geoderma 136 (2006) 20–27
Table 3
Spearman correlation coefficients between element concentrations and between each element and total PAH concentrations in the soils: *P b 0.05,
**P b 0.01, ***P b 0.001
Cd
Cr
Cu
Fe
Mn
Pb
V
Zn
ΣPAHs
1
− 0.570**
0.426*
NS
NS
0.770***
− 0.519**
0.740***
NS
Cd
1
NS
0.730***
NS
− 0.730***
0.780***
− 0.503*
NS
Cr
1
NS
NS
NS
NS
NS
0.606**
Cu
1
NS
− 0.541**
0.700***
NS
NS
Fe
Fig. 2 and were repetitive among the samplings. Phe,
Fla, Pyr, BbkjF, BaP and BghiP were among the most
abundant PAHs both in the control and urban soils
(Fig. 2). Nap showed high concentrations in the control
soils, whereas benzo[g,h,i]perylene showed high concentrations in the urban soils (Fig. 2). In the soil at
the site near the highway (U5), Cor showed the highest
percentage contribution to the ΣPAH concentration
(Fig. 2).
In Table 3 the correlations are reported among the
element concentrations and between each element and
ΣPAH concentrations in the soils. Various elements
were correlated to one another and the ΣPAHs were
correlated to Cu, Pb and Zn (Table 3). The soil trace
element concentrations were not correlated to organic
matter content and pH, with the exception of Mn that
was negatively correlated to organic matter (P b 0.05)
and positively correlated to pH (P b 0.01). ΣPAH concentrations were negatively correlated to soil organic
matter (P b 0.001). The same results were obtained for
each PAH.
4. Discussion
The findings of the investigated compounds show
a clear separation between the control and urban soils.
The highest concentrations of both some trace elements
and PAHs indicated an accumulation in urban soils,
attributable to air deposition, although a contribution
to the total concentrations of some investigated
elements could also come from the bedrock. The higher concentrations of Cr, V and Fe in the control soils
are attributable to the strictly volcanic origin of the
substrate. Particularly conspicuous was Cr content,
about two fold higher than the content in each urban
soil. De Nicola et al. (2003) found higher Cr and V
concentrations in the deeper layer (15–20 cm) than in
the surface layers at various sites of the Vesuvius
National Park, suggesting clear derivation of these
1
NS
NS
NS
NS
Mn
1
− 0.730***
0.880***
0.485*
Pb
1
− 0.511*
NS
V
1
0.600**
Zn
1
ΣPAHs
elements from the volcanic substrate. Giammanco et al.
(1996) found soil Fe and V resulting from the volcanic
substrates of Mount Etna (Sicily). The higher concentrations of Pb, Zn, Cd and Cu in the urban than
control soils are due to air deposition. Cr and Fe are
also abundant in the air deposition in the urban area of
Naples (Alfani et al., 2000) but the high background
values hide the atmospheric contribution. Pb and Zn
showed great accumulation in urban soils with
concentrations almost two fold higher than in control
soil. Pb and Zn were more abundant at site U5 near
the highway. It is well known that trace element contamination of urban soils is caused especially by
vehicular traffic (Berthelsen and Steinnes, 1995; Bloemen et al., 1995; Alfani et al., 1996; Pichtel et al.,
2000; Maisto et al., 2004a).
Typical soil concentrations of ΣPAHs from rural
areas are estimated at about 100 ng g− 1 d.w. (Edwards,
1983; Trapido, 1999); the higher concentrations
detected in the urban soils suggest that the latter sites
are affected by considerable air deposition. Our findings
show PAH contents in urban soils 2–20 times higher
than in control soils. The comparable trend of each PAH
in the urban soils suggests that air deposition influences
the PAH soil profile in the same way. The high percentage of benzo[g,h,i]perylene and coronene in the
urban soils is attributable to their continuous emission
by vehicular traffic and consequent deposition (Cretney
et al., 1985; Yang et al., 1991; Amagai et al., 1999).
Moreover, the relatively high resistance of these
compounds to degradation contributes to their accumulation in soils (Johnsen et al., 2005). In the soil collected
at site U5 (near the highway, affected by heavy continuous traffic flow), the high contribution of coronene
could be attributed to the load of vehicles that use diesel
fuel, whose combustion emits high levels of this PAH
(Mastral et al., 2003). The higher percentages of some
PAHs, such as naphthalene, in the control soil, suggest a
source other than urban. Naphthalene would seem to
G. Maisto et al. / Geoderma 136 (2006) 20–27
derive from natural sources such as plant and microbial
metabolism (Borneff et al., 1968; Wilcke et al., 1999).
The higher percentages of naphthalene found in urban
soils rich in organic matter (U1 and U5) with a dense
plant cover also support a biological source in urban
soils (Wilcke et al., 1999; Atanassova and Brümmer,
2004). The correlations found between PAHs and Cu,
Pb and Zn concentrations suggest a common source for
some PAHs and trace metals. Indeed, several authors
show the relationship of some PAHs and trace elements
with high traffic load (Bloemen et al., 1995; Chen et al.,
1997; Pichtel et al., 2000).
The wide range of the organic matter in the urban
soils appears to depend on litter removal. At the urban
sites, U2 and U5, with rich grass cover and abundant
litter, the organic matter contents show values similar to
those found in the control soils. Variations in soil water
contents are related to organic matter due to the capability of the latter to hold water. The urban soils rich in
organic matter and with good water availability also
exhibited a higher microbial biomass and oxidative
metabolism, as shown by basal respiration.
The negative correlation between PAH soil concentrations and soil organic matter contents could be explained by the accumulation of PAHs due to scarce
microbial activity depending on scarce availability of
resources from litter. The site along the highway
(U5) with the highest PAH depositions, evaluated by
PAH Q. ilex leaf concentrations (Maisto et al., 2004b),
showed values in the soils which were among the
lowest at the urban sites. At this site, the rich amount of
soil organic matter and rapid microbial activity appear
to enhance high PAH biodegradation that determines a
low soil accumulation of PAHs, while trace elements,
particularly Pb and Zn, exhibited the highest accumulation. Sites U3 and U4 with a PAH deposition
comparable to site U5 (unpublished data), but a scant
microbial metabolism, exhibited the highest PAH
accumulation in the soil. Compact soils, with scant
oxygen, low water and low organic matter content
are unfavourable to soil microbial activity and PAH
biodegradation (Blakely et al., 2002; Johnsen et al.,
2005). In soils with low organic matter content
microbial growth is limited, and microbial biomass
and activity are lower than in soils rich in organic
matter. Moreover in OM-poor soils, fungi could
produce lower amounts of oxidative enzymes (Gramss
et al., 1999) such as lignin peroxidases and manganese
peroxidases which are presumed to be involved in PAH
degradation (Augustin and Muncnerova, 1994). PAH
degrading fungi isolated from contaminated soils
showed different abilities to degrade PAHs of different
25
molecular weight. Some of these fungi show a
surprising ability to degrade highly condensed PAHs
more efficiently than less condensed ones (Potin et al.,
2004). However, the pollutant accumulation level found
in Naples does not appear to have inhibited soil
microbial activity that in some urban soils appears as
considerable as in control soil. Also Johnsen et al.
(2005) reported that diffuse pollution along roads is not
toxic for PAH-mobilizing organisms. Not only biodegradation but also irreversible sorption, volatilisation
and leaching are possible pathways that control soil
PAH concentrations (Reilley et al., 1996).
The highest element concentrations in the control
soils recorded in September could be due to a further
input of these elements in the surface soils from May to
September due to the accumulation of dead leaves of
Q. ilex L. that fall in late spring. In the urban soils, the
highest element concentrations are not always detected
in the same sampling, probably due to the heterogeneity
of the urban soils and to various anthropogenic factors,
such as quality and quantity of emissions, and possible
litter removal, depending on the investigated site. The
higher PAH concentrations in the control soils in
January could be attributed to the low air temperatures
that increase the affinity of the PAHs to the matrix with
respect to the air. Variation in PAH air/leaf and air/soil
partitioning with seasonality is widely reported (Kömp
and McLachlan, 1997; Howsam et al., 2001; De Nicola
et al., 2005). The PAH concentrations detected in the
urban soils did not show the same temporal trend of the
control soil, attributable to the heterogeneity of the
urban soils, depending on the organic matter content
(Kohl and Rice, 1999), the grass and litter cover
(Cousins et al., 1999; Maisto et al., 2004b) and, probably, on continuous PAH emissions over the year at the
urban sites. However, our findings demonstrate a clear
spatial separation not only between control and urban
soils but also among urban soils. In the volcanic studied
soil, PAH net accumulation is affected not only by
deposition but also by microbial decomposition. In fact,
the urban soils with highest organic matter and
microbial activity showed lowest PAH accumulation.
Trace elements from the volcanic pedogenic substrate
appear to hide air deposition of trace elements in the
urban soils.
5. Conclusions
Pb, Zn and ΣPAHs showed a substantial accumulation in the urban soils whereas Cr, V and Fe showed
higher values in control soils. The distribution in soils
of PAHs, unlike that of trace elements, would seem
26
G. Maisto et al. / Geoderma 136 (2006) 20–27
affected by soil organic matter and microbial metabolism. In addition to air deposition, the pedogenic substrate affects trace element concentrations in the soil.
Further investigation could be required to highlight
the main pathways of inputs and outputs of both trace
elements and PAHs, regulating their accumulation in
the soils.
Acknowledgements
This work was financially supported by MIUR
(PRIN 2000 — MM05188955_001).
References
Adriano, D.C., 1986. Trace Elements in the Terrestrial Environment.
Springer Press, Berlin, Heidelberg, New York.
Alfani, A., Bartoli, G., Rutigliano, F.A., Maisto, G., Virzo De Santo,
A., 1996. Trace metal biomonitoring in the soil and the leaves of
Quercus ilex in the urban area of Naples. Biol. Trace Elem. Res.
51, 117–131.
Alfani, A., Baldantoni, D., Maisto, G., Bartoli, G., Virzo De Santo, A.,
2000. Temporal and spatial variation in C, N, S and trace element
contents in the leaves of Quercus ilex L. within the urban area of
Naples. Environ. Pollut. 109, 119–129.
Amagai, T., Takahashi, Y., Matsushita, H., 1999. A survey on
polycyclic aromatic hydrocarbon concentrations in soil in ChiangMai, Thailand. Environ. Int. 25, 563–572.
Atanassova, I., Brümmer, G.W., 2004. Polycyclic aromatic hydrocarbons of anthropogenic and biopedogenic origin in a colluviated hydromorphic soil of Western Europe. Geoderma 120,
27–34.
Augustin, J., Muncnerova, D., 1994. Degradation pathways of
aromatic hydrocarbons in fungi and bacteria. Biologia 49,
289–299.
Baek, S.O., Field, R.A., Goldstone, M.E., Kirl, P.W., Lester, J.N., Perry,
R., 1991. A review of atmospheric polycyclic aromatic hydrocarbons: sources, fate and behaviour. Water Air Soil Pollut.
60, 273–300.
Berthelsen, B.O., Steinnes, E., 1995. Accumulation patterns of heavy
metals in soil profiles as affected by forest clear-cutting. Geoderma
66, 1–14.
Blakely, J.K., Neher, D.A., Spongberg, A.L., 2002. Soil invertebrate
and microbial communities, and decomposition as indicators of
polycyclic aromatic hydrocarbon contamination. Appl. Soil Ecol.
21, 71–88.
Bloemen, M.L., Markert, B., Lieth, H., 1995. The distribution of Cd,
Cu, Pb and Zn in topsoils of Osnabrück in relation to land use. Sci.
Total Environ. 166, 137–148.
Borneff, J., Selenka, F., Kunte, H., Maximos, A., 1968. Experimental
studies on the formation of polycyclic aromatic hydrocarbons in
plants. Environ. Res. 2, 22–29.
Chen, T.B., Wong, J.W.C., Zhou, H.Y., Wong, M.H., 1997.
Assessment of trace metal distribution and contamination in
surface soils of Hong Kong. Environ. Pollut. 96, 61–68.
Cousins, I.T., Gevao, B., Jones, K.C., 1999. Measuring and modelling
the vertical distribution of semi-volatile organic compounds in
soils. I: PCB and PAH soil core data. Chemosphere 39,
2507–2518.
Cretney, J.R., Lee, H.K., Wright, G.J., Swallow, W.H., Taylor, M.C.,
1985. Analysis of polycyclic aromatic hydrocarbons in air
particulate matter from a lightly industrialised urban area. Environ.
Sci. Technol. 19, 397–404.
De Nicola, F., Maisto, G., Alfani, A., 2003. Assessment of nutritional
status and trace element contamination of holm oak woodlands
through analyses of leaves and surrounding soils. Sci. Total
Environ. 311, 191–203.
De Nicola, F., Maisto, G., Prati, M.V., Alfani, A., 2005. Temporal
variations in PAH concentrations in Quercus ilex L. (holm oak)
leaves in an urban area. Chemosphere 61, 432–440.
Di Gennaro, A., 2002. I sistemi di terre della Campania. Risorsa e
Regione Campania, Naples, Italy.
Edwards, N., 1983. Polycyclic aromatic hydrocarbons (PAHs) in
the terrestrial environment — a review. J. Environ. Qual. 12,
427–441.
Giammanco, S., Valenza, M., Pignato, S., Giammanco, G., 1996. Mg,
Mn, Fe and V concentrations in the ground waters of Mount Etna
(Sicily). Water Res. 30, 378–386.
Gramss, G., Voigt, K.-D., Kirsche, B., 1999. Degradation of polycyclic
aromatic hydrocarbons with three to seven aromatic rings by
higher fungi in sterile and unsterile soils. Biodegradation 10,
51–62.
Howsam, M., Jones, K.C., Ineson, P., 2001. Dynamics of PAH
deposition, cycling and storage in a mixed-deciduous (QuercusFraxinus) woodland ecosystem. Environ. Pollut. 1136, 163–176.
Index to EPA test methods, 2003. Peg, N. (Ed.), US EPA New England
Region 1 Library, Boston, MA USA.
Johnsen, A.R., Wick, L.Y., Harms, H., 2005. Principles of microbial
PAH-degradation in soil. Environ. Pollut. 133, 71–84.
Kabata-Pendias, A., Pendias, K., 1992. Trace Elements in Soils and
Plants. CRC Press, Boca Raton, Florida.
Kohl, S.D., Rice, J.A., 1999. Contribution of lipids to the nonlinear
sorption of polycyclic aromatic hydrocarbons to soil organic
matter. Org. Geochem. 30, 929–936.
Kömp, P., McLachlan, M.S., 1997. Influence of temperature on plant/
air partitioning of semivolatile organic compounds. Environ. Sci.
Technol. 31, 886–890.
Maisto, G., Baldantoni, D., De Marco, A., Alfani, A., Virzo De Santo,
A., 2003. Biomonitoring of trace element air contamination at sites
in Campania (Southern Italy). J. Trace Elem. Med. Biol. 17 (1),
51–55.
Maisto, G., Alfani, A., Baldantoni, D., De Marco, A., Virzo De Santo,
A., 2004a. Trace metals in the soil and in Quercus ilex L. leaves at
anthropic and remote sites of the Campania Region of Italy.
Geoderma 122, 269–279.
Maisto, G., De Nicola, F., Prati, M.V., Alfani, A., 2004b. Leaf and soil
PAH accumulation in an urban area of the Mediterranean region
(Naples-Italy). Fresenius Environ. Bull. 13 (9), 1263–1268.
Mastral, A.M., López, J.M., Callén, M.S., García, T., Murillo, R.,
Navarro, M.V., 2003. Spatial and temporal PAH concentrations in
Zaragova, Spain. Sci. Total Environ. 307, 111–124.
Pichtel, J., Kuroiwa, K., Sawyerr, H.T., 2000. Distribution of Pb, Cd
and Ba in soils and plants of two contaminated sites. Environ.
Pollut. 110, 171–178.
Potin, O., Rafin, C., Veignie, E., 2004. Bioremediation of an aged
polycyclic aromatic hydrocarbons (PAHs)-contaminated soil by
filamentous fungi isolated from the soil. Int. Biodeterior.
Biodegrad. 54, 45–52.
Reilley, K.A., Banks, M.K., Schwab, A.P., 1996. Dissipation of
polycyclic aromatic hydrocarbons in the rhizosphere. J. Environ.
Qual. 25, 212–219.
G. Maisto et al. / Geoderma 136 (2006) 20–27
Schipper, L.A., Degens, B.P., Sparling, G.P., Duncan, L.C., 2001.
Changes in microbial heterotrophic diversity along five plant
successional sequences. Soil Biol. Biochem. 33, 2093–2103.
Sheu, H.L., Lee, W.J., Lin, S.J., Fang, G.C., Chang, H.C., You, W.C.,
1997. Particle-bound PAH content in ambient air. Environ. Pollut.
96, 369–382.
Sparling, G.P., 1995. The substrate-induced respiration method. In:
Alef, K., Nannipieri, P. (Eds.), Methods in Applied Soil Microbiology and Biochemistry. Academic Press, London, pp. 397–404.
Trapido, M., 1999. Polycyclic aromatic hydrocarbons in Estonian soil:
contamination and profiles. Environ. Pollut. 105, 67–74.
27
Tuháćková, J., Cajthaml, T., Novák, K., Novotný, Č., Mertelík, J.,
Šašek, V., 2001. Hydrocarbon deposition and soil microflora as
affected by highway traffic. Environ. Pollut. 113, 255–262.
Wilcke, W., Müller, S., Kanchanakool, N., Niamskul, C., Zech, W.,
1999. Polycyclic aromatic hydrocarbons (PAHs) in hydromorphic soils of the tropical metropolis Bangkok. Geoderma 91,
297–309.
Yang, S.Y.N., Connell, D.W., Hawker, D.W., Kayal, S.I., 1991.
Polycyclic aromatic hydrocarbons in air, soil and vegetation
in the vicinity of an urban roadway. Sci. Total Environ. 102,
229–240.