1,721,086 research outputs found
Risk for human health of some POPs due to fish from Lake Iseo
No full textRisk evaluation for human health was carried out using PCB and PAH concentrations measured in seven fish species from Lake Iseo (Italy) and comparing the experimental data with legal levels and the two new approaches proposed by the US FDA and the US EPA to protect local populations with different food habits. We verified that none of the persistent organic compounds analyzed exceeded the legal limits set by the US FDA, since no specific limit has yet been proposed by the European Union. The two other approaches have pointed out that the acute and chronic effects do not represent any risk for human health, while a possible carcinogenic risk for the local population can arise when 4 and 8 monthly meals are consumed, based on PCB and PAH content in the edible part of fish, respectively
DDT is still a problem in developed countries: the heavy pollution of Lake Maggiore
No full textThe Zebra mussel (Dreissena polymorpha), one of the most widely used bioindicators of persistent organic pollutants, trace metals and radionuclides in several worldwide freshwater ecosystems, has been used to monitor DDT contamination trends in Lake Maggiore since 1996, caused by industrial effluents on a tributary of the River Toce, one of the major affluents of the lake. Dreissena specimens were collected at two sampling sites, one within the Baveno Bay, where the River Toce flows, and the other outside (Villa Taranto). Total DDT levels (3119.6 ng/g lipids at Baveno and 1351.2 ng/g lipids at Villa Taranto) in the soft tissues of the Zebra mussel decreased at both stations by about 30-50% in the first year after the closure of the chemical plant reaching an almost steady-state condition. The high concentrations measured in Zebra mussel specimens of Baveno Bay in 2000 (1947 ng/g lipids) and the percentage of pp'DDE in comparison with total DDT concentration, which showed a slight increase in the last years, clearly indicate that a contamination source is still present, deriving probably from the lacustrine sediments and the River Toce. Data show that the environmental risk is very high within the Baveno Bay and the recovery time should be longer than in the other parts of the lake, where DDT levels in Dreissena are presently two times higher than those measured in the other Italian subalpine lakes
The PCB pollution of L. Iseo (N. Italy) and the role of biomagnification in the pelagic food web
No full textSeveral models of varying complexity have been used to predict pollutant concentrations in the higher levels of the food web from those in lower levels, but the role of the biomagnification process in aquatic food chains is still controversial. We used the fugacity-based approach to verify the transfer of PCBs through the pelagic food chain of Lake Iseo (N. Italy), sampling several zebra mussel specimens and some fish belonging of different trophic levels.
The zebra mussel seems to be a suitable starting species for modelling the bioaccumulation process through the trophic web, not only because its physiological characteristics and population size do not change much with time (as do algae and zooplankton) but also because it takes up toxicants exclusively from the water, as shown by the application of two predictive trophic models commonly used. The data provided by one of those models were in good agreement with our experimental data on fish in Lake Iseo, that show a not negligible uptake from food for the top predator species (pike and perch) with an increase of about three times in comparison with the PCB levels measured in the zebra mussel specimens
Sediment toxicity bioassays for assessment of a recent DDT contamination of the central basin of Lake Maggiore (Northern Italy)
No full textToxicity of 4-nonylphenol to Tubifex tubifex and Chironomus riparius in 28 day whole-sediment tests
No full textConcern has been growing recently over the toxicity and the mimicking properties of 4-nonylphenol (4NP), the most persistent breakdown product of the nonionic surfactant nonylphenol ethoxylates, broadly used in industrial cleaning processes. Twenty-eight-day tests were performed to evaluate the toxicity and the effects on reproduction of 4NP spiked sediment to the benthic invertebrates Tubifex tubifex and Chironomus riparius. 4NP was directly added to the wet sediment, avoiding any solvent. The EC50 value for the emergence of chironomids was 380 mug 4NP g(-1) dry weight (dw); the EC50 values for the deposition of cocoons and the development of young worms were very similar (428 and 420 mug g(-1) dw, respectively). Regarding NP estrogenic activity and its effects on reproduction and development, no significant differences were noted in the sex ratio of the emerged chironomids when exposed to 4NP compared to the controls, but the emerged chironomids did not lay eggs at concentrations higher than the EC10 (250 mug 4NP g(-1) dw). Furthermore, at concentration of 610 mug 4NP g(-1) dw an interference in the development of the gonads of adult worms was observed, but it was impossible to determine whether this effect was due to 4NP toxicity or to its hormone mimicking properties
Environmental quality of the Po River delta
No full textThe Po River collects the discharges of the most populated and industrialized area of Northern Italy and enters the Adriatic Sea with a mean flow of 1470 m 3 s -1 spreading in nine branches along the final stretch and forming a delta originating about 50 km from the sea. According to the last systematic survey carried out in 1989-1990, the Po delta waters suffer a low-moderate pollution from heavy metals and organic micropollutants. However, the Po River carries a nutrient load high enough to cause a severe marine eutrophication problem south of its delta. Provisional models have shown that even a substantial reduction on civil and industrial waste water discharges coupled with an optimal use of fertilizers in agriculture would not be sufficient to solve the problem. The Po River represents an important source also, for heavy metals and marine sediments collected at the river mouth are more polluted than are those offshore, especially for Cu, Zn and Hg. On the basis of the European guidelines the delta sediments have a medium to high contamination as far as the concentration of Ni and DDT are concerned, while data on persistent organic compounds indicate a moderate ecological risk for the biota living in the delta. These same conclusions can be obtained using the "sediment quality benchmark" procedure proposed by the NOAA in the United States
Phytoplankton assemblage structure and dynamics as indicator of the recent trophic and biological evolution of the western basin of Lake Como (N. Italy)
No full textBiomarkers in Zebra mussels for monitoring and quality assessment of Lake Maggiore (Italy)
No full textThree different biomarkers (acetylcholinesterase (AChE), ethoxy resorufin-O-deethylase
(EROD) and DNA strand breaks) were measured in Zebra mussel (Dreissena polymorpha)
specimens collected in April 2005 at six different sampling sites on Lake Maggiore, the second
largest Italian lake in terms of depth and volume, in order to assess the spatial variation of
exposure to man-made contaminants. Mussels maintained at fixed laboratory conditions were
used as controls to eliminate potential interference due to environmental factors. Biomarker
data were also supported by the analysis of several chemicals (six dichlorodiphenyltrichloroethane
(DDTs), 23 polychlorinated biphenyls (PCBs), 14 polybrominated diphenyl ethers
(PBDEs), 11 polycyclic aromatic hydrocarbons (PAHs) and hexachlorobenzene (HCB))
measured in the mussel soft tissues by gas chromatographic analyses. We found a negative
correlation between temperature and AChE activity, while any measured environmental or
physiological factor seemed to influence EROD activity and DNA strand breaks. A positive
relationship was found between EROD activity and all of the measured chemicals, except for
PAHs, which correlated with the amount of DNA strand breaks. Significant differences were
noted for all biomarkers, both among sampling stations and between control and experimental
data, even if the general level of variability was low. The biomarkers showed a distinct pattern of
spatial variation, but the evaluation of DNA strand breaks was the strongest discriminating
power between sites. In addition, the comparison between AChE and EROD activity measured
in 2005 was compared with results obtained in a previous study carried out over the same
sampling period in 2003. Results indicated a strong influence of temperature on AChE activity
and probable interference of substrate inhibition of EROD activity, pointing out the need to take
care in the interpretation of data comparisons. The results obtained with two different metrics
used for the measure of DNA strand breaks is also discussed, as well as the relationship between
EROD activity data and potential genotoxicity
Present status of POP contamination in Lake Maggiore (Italy)
No full textIn the last decade, Lake Maggiore has been subject to heavy DDT contamination due to a chemical plant located near the main influent of the Baveno Bay. The freshwater bivalve zebra mussel (D. polymorpha) was used as a bioindicator of several POPs (DDTs, PCBs, HCB, HCHs) to follow their concentration trend after a heavy flood in autumn 2000. Sampling of mollusc specimens were carried out monthly from April 2001 to October 2002 at two different stations in and outside the bay. Results showed worsening of DDT pollution due to the transport of insecticide from contaminated sediments and soils still present in the closed chemical plant site. Levels of about 4.5 mug/g lipids in soft tissues of specimens from the most contaminated site and 2.0 mug/g lipids outside it were found, which are twice those measured before the flood. HCHs and HCB values were always very low, but it was noticed since winter 2001-2002 a sharp increase of PCB pollution, with values of about 3-4 mug/g lipids, not due to the 2000 flood, but probably to improper discharge or release of contaminated sediments from numerous dams located in the watershed. Concentrations of total dioxin-like PCBs reached dangerous levels for the water community. Fish consumption may be a risk for human health especially for resident population, bearing in mind that fish usually have a higher POP concentration than zebra mussel
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