Giuseppe Viviano

Accidental release of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at Sèveso, Italy: II. TCDD distribution in the soil surface layer

Abstract A chemical plant failure 13 miles north of Milan, Italy produced a seriously dangerous contamination of inhabited areas, extending from the plant itself for a few kilometers in the south-southeast direction. Many environmental specimens were sampled and analyzed to assess distribution of TCDD in the soil surface layer of the territory hit so as to enable the appropriate sanitary measures to be taken. On the basis of contamination maps, three zones were established: Zone A, Zone B, and Zone R which enclosed the former two. This paper describes the procedures adopted to assess the contamination of soil due to TCDD. TCDD concentrations were seen to vary in the range 3 μg/m 2 . TCDD levels were highest in Zone A, while Zones B and R exhibited lower contamination levels of 2 , respectively.

Accidental release of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at Sèveso, Italy

The analytical techniques used for the determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) contents in environmental samples from the Seveso, Italy, area are described. Low-resolution gas-liquid chromatography in combination with MID/mass spectrometry (mass fragmentography) has proven to be an accurate and sensitive means of detecting trace quantities (parts per trillion) of TCDD when appropriate cleanup procedures are adopted. Detection thresholds were found to range between 10 and 0.2 ppt for farming soil, between 50 and 2 ppt for vegetation, and between 20 and 1 ng/m2 for “wipe test” cotton swabs. No false positive results occurred in the near 7000-sample group studied. Uncertain findings, classified as “undetermined,” occurred with an average frequency <5%. Results also show that large excesses of some PCBs and p,p′-DDT (up to 5000:1 and 500:1, respectively, vs the TCDD present in the sample) were eliminated during the clean-up phase.

Accidental release of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at Sèveso, Italy. V. Environmental persistence of TCDD in soil.

Abstract TCDD levels were determined at 44 soil sites in Zone A during three surveys carried out at different times (1, 5, and 17 months) after the ICMESA accident. The data obtained provide statistically significant ( P 1 was about 1 year, whereas 17 months after the accident, it was estimated to be > 10 years.

Accidental release of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at Sèveso, Italy: IV. Vertical distribution of TCDD in soil

Abstract Vertical distribution of TCDD has been monitored in the soil at Seveso down to a depth of approximately 30 cm at several sites and times in 1976 and 1977. A sharp decrease of TCDD levels was observed as depths increased. TCDD amounts detected more than 8 cm below the surface were, as a rule, less than those detected down to 8 cm by at least one order of magnitude. Moreover, the highest TCDD levels were not found in the topmost soil layer (0.5 cm), but very often in the second (0.5–1.0 cm) or third (1.0–1.5 cm) layers. As compared to findings obtained in 1976 for deeper soil layers, slightly, yet significant, higher levels of TCDD were detected in 1977.

Two-Years of Fine and Ultrafine Particles Measurements in Rome, Italy

Long-term aerosol measurements have been conducted at two sites in Rome, Italy, April 2001 through March 2003, in a traffic-oriented site, and at an urban background site, close to the city center. The main objective was to establish validated and consistent data sets of particle number concentrations (PNC) in Rome to be used for epidemiological analyses of cardiovascular health effects. Particle number concentrations were measured by a condensation particle counter (CPC 3022A, TSI). Other pollutants (PM10, PM2.5, CO, NO2, NO, NOx, O3) were simultaneously measured at the traffic-oriented site. During the study period, the mean (standard deviation) 24-h PNC values were 4.69 × 104 (1.99 × 104) cm−3 and 2.46 × 104 (1.10 × 104) cm−3, respectively, at the traffic-oriented site and at the urban background site. Mean (standard deviation) 24-h mass concentration of PM2.5 was 23.1 (11.9) μg m−3, while for PM10 it was 41.3 (17.9) μg m−3. Higher values for all the pollutants, except ozone, were recorded during the winter period in comparison with the summer period, and a higher variability of the results was also observed during cold months. The comparison between the daily PNC measured at the two sites showed a good correlation (r = .74). CO (r = .77), NO (r = .82), and NOX (r = .83) were all highly correlated with PNC (simultaneous obs. number 576). The diurnal and seasonal pattern of PNC can be attributed to the combined effect of motor vehicle emissions and meteorological conditions.

ENVIRONMENTAL PERSISTENCE OF 2,3,7,8-TCDD AT SEVESO

TCDD levels were determined at 44 soil sites in Zone A during three surveys carried out at different times (1, 5, and 17 months) after the ICMESA accident. The data obtained provide statistically significant (P<.01) evidence that the geometric mean of TCDD levels in the unworked soil of Zone A diminished sharply in the first six months after the accident. Following this period, no further decreases in TCDD levels were detected. Available data are consistent with the hypothesis that TCDD presence in the Seveso environment diminished with time and at a rate which also decreased with time until it eventually became ~0 (steady state). Experimental data have been fitted to two mathematical functions complying with such observations. From the steady-state function the mean TCDD levels at t=0 may be estimated to have been from 5 to 11 times as high as steady-state values.

Accidental release of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at Sèveso, Italy: VI. TCDD levels in atmospheric particles

Abstract TCDD in atmospheric dust was monitored in the Seveso area between 1977 and 1979 using both dustfall jars and high-volume samplers. Apart from the sampling site in Subzone A1, sporadic TCDD levels were detected at different times and different sites throughout the contaminated area. Variable amounts of TCDD were constantly detected at the sampling site located in the most heavily contaminated subzone. All findings were in the range of 0.06–2.1 ng of TCDD/g of dust, for dustfall jar specimens, and 0.17–0.50 ng of TCDD/g of dust, for samples from high volume samplers.

Accidental release of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at Sèveso, Italy. III. Monitoring of residual TCDD levels in reclaimed buildings.

Abstract The uneven distribution of TCDD in soil and on internal and external building surfaces of Subzones A6 and A7 was a main problem when assessing the effectiveness of decontamination operations. Consequently, Subzones A6 and A7 were broken down into smaller sections to identify building clusters with more homogeneous TCDD levels and distribution patterns. Three clusters were the basic units for stratified samplings. After all decontamination operations had been completed, a minimum of 113 randomly selected samples for each cluster were taken from building inside surfaces and analyzed. All the values were within the maximum tolerated level of TCDD. Similar results were also obtained from outside walls and from soil.

METHODOLOGICAL PROBLEMS IN ASSESSING 2,3,7,8-TCDD ENVIRONMENTAL CONTAMINATION AT SEVESO

ABSTRACT The statistical distribution of TCDD levels in the Seveso area following the ICMESA accident is described. A Poissonian model is hypothesized to explain the nonGaussian, asymmetric and tailing off statistical distribution of TCDD levels in soil. Two categories of discrete contaminated particles are hypothesized as responsible for the TCDD contents in soil specimens. Log-transformation of data is used to obtain normality of distribution. Analysis of variance on transformed data of replicated TCDD measurements in Zone A enabled “site difference” and “error” variances to be estimated. Causes for measurement fluctuations are discussed. Standard deviation as derived from error variance has been found to be about 0.6 log units (natural logarithms), i.e. a factor of approximately 2 for original data. Application of the methodology to other similar situations is mentioned.

Physico-chemical characterization of crystalline phases in fly ashes

Fuel oil combustion in power plants, domestic heating systems and diesel engines, causes the emission in the environment of particles with a typical structure and composition: the cenospheres.These particles are produced during the microdrop fuel oil combustion, when air and fuel are injected into the combustion chamber; they have a spheroidal morphology and a spongy structure.Cenospheres are constituted by an amorphous component rich in C, S, Si, Fe and Al; phases composed by microcrystals of sulphates, oxides and pure metallic elements or their alloys, are frequently present in the cenospheres.These crystalline phases are important from environmental and toxicological points of view both because they are composed of heavy metals, and because they can play an important role in heterogeneous catalysis.We started to study these crystalline phases by analytical electron microscopy techniques and electron energy loss spectrometry to define and characterise their structure and composition.