Pesticide Residues in Vegetation - Pesticides: Evaluation of Environmental Pollution - page 311

4

HCB

3

2

1

0

1990 1994 1998 2002 2006 2010

FIGURE 10.6
Temporal evolution of concentration of HCB in vegetation samples from 33 countries around the world.

Figure 10.6 shows the temporal evolution of HCB concentration in different plant species
collected from around the world. The high values found in Estonia and Germany in 2004
by Hellström are not represented in the figure because they were considered outliers. There
is a slight tendency of the concentrations of the compound to decrease over the years. This
agrees with the data reported by Barber et al. (2005) about emissions and global distribu-
tion of this pollutant. The use of this pesticide was banned for the first time in Argentina
and Hungary in the 1960s; in the following decades, between 1970 and 2000, the use of HCB
had been banned in most countries. Currently, its use is only allowed in China and Russia
(Barber et al. 2005).

10.3.3 Distribution of Pesticides in Vegetation Species

The most studied plant species to determine the presence of pesticides in natural plants
have been the genus Pinus ( P. sylvestris and P. canariensis mainly), lichens/mosses, and man-
goes ( M. indica ). Together, the Pinus species account for approximately 75% of total studies
on vegetation. In general, it can be said that the Pinus spp. were used as an indicator of
pesticide contamination in the Northern Hemisphere, while in the Southern Hemisphere,
the mango ( M. indica ) plants were used. Lichens and mosses have been studied in several
areas throughout the world due to their worldwide distribution. The rest of the performed
works were focused on different herbaceous species and other aquatic plants. Figures 10.1
through 10.3 show a worldwide distribution of the studies on different species. The results
obtained in these species have been discussed in section “Geographical Distribution”.
DDT has been studied mainly in tree species, highlighting the genus Pinus ( P. sylves-
tris and P. canariensis ) and mangoes ( M. indica ). Also, studies have been carried out in
other species such as Larix decidua, P. nigra , Tilia platyphyllos , Picea abies , Thuja occidentalis ,
and spruce ( Abies alba ). DDT was also analyzed in lichens and mosses and in a variety of
herbaceous plants ( Cy. striatus , A. sativa , V. sativa , S. nigra , and Ch. vulgare ), as well as in
aquatic species ( Ruppia cirrhosa , Cymodocea nodosa , Caulerpa prolifera , Enteromorpha flexuosa, ,
C. linum , Laurencia obtusa , Hypnea cervicornis , and Acetabularia calyculus ). The maximum
concentration of DDT, concretely p,p'-DDT, was found in mangoes ( M. indica ) in Tanzania
(Mahugija-Marco and Kisimba 2007).
HCH has been analyzed in a variety of plant species, particularly lichens, herbaceous
plants, aquatic plants, and marine and woody vegetation. The species of these three
groups of plants are the cited ones for DDT. Results obtained from herbaceous species
were particularly high, ranging from 10 mg/kg of δ-HCH in S. nigra to 40.26 mg/kg of
β-HCH in Cy. striatus (Barriada-Pereira et al. 2005), but it should be noted that the study