| |
|
1.
The
water
bodies
of
the
North
Italian
Plain |
|
The study of the ecotoxicological conditions of water bodies
is a tool used for estimating the level of environmental
pollution in general. During the three-year period 1995-1997
experimental research was performed on the variations in
ecotoxicological conditions of 24 of the main tributaries of
the Po, with samples taken at six-monthly intervals – April
and October – at 29 sites. In particular, a Piedmontese
river, the Sangone was divided into six sections.
We examined both the effluent water, a precarious component
of the conditions of water bodies, and the bottom sediment.
Although the latter varies as a result of human activity
and natural phenomena it is a less transitory and provides
a better indication of the degree of pollution. Several
direct parameters of the potential risk were determined
from the samples. The content of the bottom sediment was
examined for several heavy metals considered more harmful
for human health. Both the effluent water and the pore water
of the bottom sediment, but above all the liposoluble
organic compounds extracted from the sediment particulate,
were checked for toxicity in a series of four biological
tests, consisting of living species which are highly
sensitive to the harmful action of various classes of
environmental poisons. This approach, albeit not absolute
and which can be further developed, provided a complete
picture of the pollution in the river sediment. Examination
of the bottom particulate generally confirmed expectations
for rivers rising in the Apennines or the Alps and clearly
indicated the level of risk of acting as pollutant sinks,
with a greater risk for clay-loam sediments compared to
sandy ones. Another particularly important parameter is the
connection between rainfall and the concentration of risks
linked to effluent water or bottom sediment. During the
three-year observation period, the ecotoxicological
conditions of the water bodies varied, sometimes
deteriorating or, in some cases, showing considerable
improvements. The research results generally confirm the
expectations not only regarding the hydrogeological
situations, but also and especially those regarding the
sites of agricultural or industrial production plants. The
absence of suitable treatment plants aggravated the
situation. Clear and significant examples were the Sangone,
Olona, Lambro, Mincio, Secchia and Panaro rivers. The data
collected testify a serious level of sporadic pollution in
the Sangone (Piedmont), whilst the other rivers showed a
constant level of pollution, with the highest levels in the
Lambro and the Mincio. Pollution in the latter two rivers
showed no low point. Particularly worrying was the level of
mercury in the Mincio’s bottom sediment, if we remember how
harmful this metal is for the nervous system in adults and
foetuses, as well as causing damage to the kidneys, both in
experimental animals and man. Such damage is documented by
the scientific literature on mercury. From the results of
the concentrations of the most harmful heavy metals,
integrated with in vitro toxicity levels on series of
biological tests, a ranking was drawn up for the seriousness
of pollution of the various river basins, the Agogna was
least polluted, whilst the worst were the Sangone, Olona,
Lambro and Mincio.
|
|
po valley:
final
classification |
|
|
Ranking
|
Water body
|
Score |
|
1 |
13 Agogna
|
3.4 |
|
2 |
02 Pellice |
6.1 |
|
3 |
09 Stura Demonte |
6.5 |
|
4 |
01 Po-Villafranca |
7.0 |
|
5 |
07 Dora Baltea |
7.2 |
|
6 |
08 Sesia |
7.3 |
|
7 |
14 Terdoppio |
7.4 |
|
8 |
06 Orco |
8.5 |
|
9 |
19 Adda |
9.0 |
|
10 |
15 Ticino |
9.6 |
|
11 |
05 Stura Lanzo |
9.7 |
|
12 |
18 Trebbia |
11.3 |
|
13 |
24 Panaro |
13.3 |
|
14 |
21 Oglio |
14.0 |
|
15 |
12 Scrivia |
14.4 |
|
16 |
23 Secchia
|
14.9 |
|
17 |
04 Dora Riparia |
15.1 |
|
18 |
20 Taro |
15.6 |
|
19 |
11 Bormida |
16.3 |
|
20 |
10 Tanaro |
17.4 |
|
21 |
03 Sangone |
20.8 |
|
22 |
16 Olona |
20.9 |
|
23 |
17 Lambro |
21.3 |
|
24 |
22 Mincio |
21.3 |
|
|
2.
Piedmontese
water
bodies |
During 1996 and 1997, the experimental monitoring model applied to
24 tributaries of the Po, was extended to three Piedmontese
hydrogeological basins of considerable environmental importance:
the basin of the river Torto, the Chiusella valley and the section
of Po river park at Valenza (provinces of Vercelli and
Alessandria).
The findings confirm the relationship between the levels of
toxicity linked to river sediments with a predominantly clay-loam
composition of the sediment particulate, as well as to the
concentration of lipophilic material. The first parameter could
depend on the orographic conditions of the river valley, but the
second is mainly due to human activity. Variations of these
conditions over time may reflect the serious and prolonged drought
of the first few months of 1997.
The
systematic study model of the water of the Torto, with sampling –
every hour for a whole day – allowed us to find the effects of
human activity on pollution through the changes in bacterial
load. Maximum attention should be given to these effects, and
suggest that this experimental model should be applied to water
bodies which have been and still are the subject of environmental
degradation, as a result of malice or neglect.
During 2000 the ecotoxicological conditions of two small rivers
in the Turin hinterland, the Banna and the Tepice, were studied.
The study of different sites along the two rivers, chosen
according to both the distribution of agricultural and industrial
production facilities, and residential areas – namely farms,
industries and urban centres – once again showed the close
connections between the components of this interactive triangle
which sees man as the protagonist and target of the pollutants
which he remorselessly releases into the environment to have an
easier life, but perhaps not a better one or a longer one.
Emblematic, despite the expectations of some researchers, is the
metamorphosis of the pre-Chieri Tepice and the post-Chieri Tepice.
The inhabitants of the area are living witnesses – they have to
put up with a terrible stench in the hot summer months. Then,
after collecting the sewage of the urban areas on one hand, and
the discharge from cowsheds and pigsties on the other, these two
unfortunate rivers flow towards their destination, the Po. When
they reach the Po , their condition is better. In fact both the
pollution of the effluent water and the negative parameters of the
bottom sediment seem to improve, patchily. Perhaps this cannot be
ascribed to a miraculous bio-purification. As far as the water is
concerned, dilution and capture by the sediment could be the
cause of this apparent improvement, as happened with cyanide in
the Danube. As far as the bottom sediment is concerned, it must be
admitted that its quality depends on the distance from the
polluting sewage. It should not be forgotten that a flood can
carry downstream the poisons adsorbed at a particular site. The
research of Cai et al., (1995) on the epidemic of Itai-Itai
disease in Dayu County, China, can serve as a lesson in this
regard. In fact the time-bomb can explode at any time, and after
it will be no use crying wolf, it will not be a tragic fatality
but tragic bloodymindedness.
3.
Cecina Valley
(Tuscany)
water
bodies
|
|
During the years 1998/1999 the experimental model was
applied to the water bodies of the river Cecina basin. In
Tuscany too, effluent water and bottom sediment samples
were taken both the river Cecina and some of its main
tributaries and then studied in the laboratory.
The determination of the heavy metals present in the bottom
sediment showed the presence of some of the most dangerous
elements to human health, namely: aluminium, arsenic,
cadmium, cobalt, chrome, iron, manganese, copper, mercury,
nickel, lead and zinc. The concentration of some of these
(As, Cu and Hg) present in certain sampling sites was much
higher than the average concentration in the Earth’s crust:
this is a clear indication of man-made environmental
pollution .
|
|
cecina
valley |
|
|
|
 |
|
|
|
 |
|
|
The
case of mercury is particularly interesting. This element which is
toxic to the nervous system and the kidneys was found in high
concentrations in the Botro (creek) di Santa Maria, in the Cecina
just after the convergence with the creek and in the river
Possera. Our publicly presented results stimulated the public
authorities responsible for environmental control to determine the
mercury content not only in the effluent water but also in the
bottom sediment: miraculously, by following these
procedure, a high degree of mercury pollution emerged in the
Cecina Valley, with values sometimes higher than those encountered
by our research unit (100 ppm in the Botro di Santa Maria against
5.6 of our previous research). A year after the first meeting in
Cecina, officials of the public agency confessed that the content
of mercury in the water was within the legal limits, but the
problems started when the sediment was considered.
Furthermore, several artificial water bodies were examined. These
were located at the entrance or exit of an industrial plant. The
delivery, the quantity of calcareous mineral substances dumped
into the sea and the quantity of mercury present in the sediment
were measured. As far as the Fosso Bianco channel is concerned, a
very high concentration of mercury was found in the sediment and
of calcareous substance in the water. Probably the latter was used
as a sort of cover for the stratum of mercury dumped into the sea
in previous decades, which can be found in the sea bed off
Castiglioncello. This ploy could guarantee a certain protection
from the dispersion of mercury, if it were not for the fact that
the protective function could be wiped out by the first sea storm.
A fact that should be pointed out regarding risk for human health
is that regarding Tuscan fish-life, whether resident or seasonal.
It could behave in the same way as in Minamata, Japan. By taking
in mercury and concentrating it in their flesh, fish transform it
into a deadly organic compound – methyl-mercury – which man can
then take in by consuming the fish. |
