Paolo Tremolada

Chlorinated hydrocarbons in pine needles in Europe : fingerprint for the past and recent use

Pine needles have been demonstrated as a useful monitoring matrix for the evaluation of the tropospheric contamination levels of persistent chlorinated hydrocarbons, such as DDTs, HCHs, and HCB. Global chlorinated hydrocarbon distribution has been investigated with major attention to remote areas, while the factors affecting the distribution trends in regions of major use are less known. Six countries in Europe were analyzed by the transect sampling mode. Homogeneous contamination intensities were present within each transect, and correspondence factor analysis was used for the characterization of the typical distribution patterns

Coumaphos distribution in the hive ecosystem: Case study for modeling applications

Pesticides are currently used inside hives, against the honeybee parasite Varroa destructor, producing unwanted contamination effects. To assess the distribution and fate of one of these pesticides (coumaphos), two experimental hives were treated with Perizin (the commercial product containing the active ingredient coumaphos). Samples of honey, wax, pollen, adult bees and larvae taken before treatment and up to 104 days afterwards, showed diffuse contamination. Wood hedges and wax bridges, where the pesticide solution was applied, were analysed as well. A mass balance was calculated, yielding a recovered amount of around 60% just after treatment and 38% 1 month later. Directly contaminated surfaces and wax contained the highest amount of residues. Wax and honey contained different amounts (10, and 0.1% respectively) but both retained residues for long time. Bees ingest most of the product just after treatment, then rapidly eliminate it by metabolism, advection and deposition processes. On the basis of analytical results, a simple model (level I of the fugacity model) was applied to the hive system for different pesticides (coumaphos, malathion, fluvalinate and bromopropylate). Predicted concentrations in wax and honey were compared with those measured, indicating the good predictive capability of this approach.

A study of the spatial distribution of PCBs in the UK atmosphere using pine needles

Past and current polychlorinated biphenyl (PCB) inputs to the environment, mainly in industrialized countries, continue to determine a global re-distribution of these contaminants. In order to better understand PCB transport and distribution phenomena, a number of large-scale distribution studies have been recently published in the literature. In this paper a nationwide survey of 28 pine needle samples taken across the UK is presented. Mean PCB concentrations of a number of latitudinal bands (transects) revealed the presence of a decreasing concentration gradient from southern England to northern Scotland of a factor of 7. The pine needle data also provide evidence to suggest: 1) that there has been a decrease in the PCB concentration of the atmosphere in the southern UK; and 2) there is a relationship between regional mean needle PCB concentrations and population densities. Calculated air concentrations from the pine needle results were compared with measured literature data of a similar area to test the possibility of using bioconcentration factors (BCF) based on n-octanol: air partition coefficients (Koa) to predict air-leaf equilibrium of semivolatile organic compounds. A more detailed analysis, in accordance with some literature data, has revealed that uncertainties arise when leaf-air uptake of molecules with high Koa values (Log Koa > 8–9) is modelled.

Preferential retention of POPs on the northern aspect of mountains

Soils are the main reservoirs of POPs in mountain ecosystems, but the great variability of the concentrations, also at small scale, leaves some uncertainties in the evaluation of environmental burdens and exposure. The role of the aspect of the mountain side and the seasonal variation in the contamination levels was analysed by means of several soil samples taken from central Italian Alps. A greater contamination content was present in northern soils with a mean ratio between the north vs. south normalised concentration of around a factor of 2 (North-South Enrichment Factor). Experimental factors agreed with theoretical calculations based on temperature-specific calculated K(sa) values. From May to November consistent differences in normalised concentrations up to 5-fold were observed. A dynamic picture of the POP contamination in high altitudinal soils is derived from the data in this work, with spring-summer half-lives between 60 and 120 days for most of the compounds.

PCB distribution in soil and vegetation from different areas in Northern Italy

PCB concentrations in foliage and in soil, as indices of environmental contamination, were measured in different areas of northern Italy. Samples were taken from highly industrialized sites of the plain area and from mountains characterized by very low human impact. In order to describe distribution and transport patterns, the results were evaluated in function of the properties of the different congeners and elaborated by means of Correspondence Factor Analysis (CFA). PCBs seem to be ubiquitous contaminants in Northern Italy but CFA indicates an increase in the concentration of higher molecular weight PCB congeners in areas far from emission sites. Through CFA some differences in the relative composition of soil and foliage samples can be highlighted, suggesting different transport patterns among congeners.

Seasonal changes and temperature-dependent accumulation of polycyclic aromatic hydrocarbons in high-altitude soils.

Polycyclic Aromatic Hydrocarbons (PAHs) are a major group of pollutants whose occurrence in the environment is mainly of anthropogenic origin. In this paper, we examine the effect of topographical slope exposure on PAH contamination and seasonal change in PAH concentrations in soils. We collected soil samples on three dates in 2007 (early May, end of July and beginning of November) from south- and north-facing aspects at 1900 m a.s.l. in the central Italian Alps. We found greater PAH contamination in soils from a north-facing slope than in those from a south-facing slope at all seasons. We calculated North-South Enrichment Factors as the ratio between the concentrations measured in soils from northern and southern aspects. These ratios ranged from 1.4 to 1.9 for lighter PAHs (from 2 to 4 rings). These values are consistent with theoretical calculations based on temperature-specific octanol-air partition coefficients (predicted North-South Enrichment Factors range from 1.6 to 2.0). For heavier PAHs (from 5 to 6 rings), smaller differences were observed between soils from northern and southern aspects, due to the gas/particle distribution of these compounds. We also found consistent differences in normalised PAH concentrations across the three sampling periods. The majority of compounds showed a significant decreasing trend from the beginning of May to the end of July, due to the annual cycles of physical processes (deposition vs. volatilisation) and biological processes (uptake and/or biotransformation). Only a few compounds showed different trends, presumably due to season-specific local emission sources.

Background levels of polybrominated diphenyl ethers (PBDEs) in soils from Mount Meru area, Arusha district (Tanzania)

This study investigates the contamination by 13 polybrominated diphenyl ether (PBDE) congeners in an altitudinal soil transect on Mt. Meru area, Northern Tanzania. A ∑13PBDEs mean concentration of 386±200 pg/g d.w. (4900±3500 pg ∑13PBDEs/g soil organic matter - SOM) was measured, pointing out that, in a prevalently agricultural area from the southern hemisphere, PBDE contamination can be even higher than in similar semi-remote environment of industrialized country of the northern one. The Mt. Meru PBDE pattern of contamination was characterized by the prevalence of intermediate brominated congeners (tetra- and penta-BDEs). Among the detected compounds, BDE-47 was the main congener, followed by BDE-99, BDE-190 and BDE-100. The distribution of PBDEs confirmed that organic carbon had a substantial impact on their accumulation in Tanzanian soils. The altitudinal profile of PBDEs (log TOC-normalized concentrations) fitted a second order polynomial model with altitude, with an initial concentration decrease, interpreted as a dilution effect from local/regional sources, and a following consistent increase with altitude according to the cold condensation theory. Evidences of distillation effect among PBDE congeners were also observed.

Seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk from a high altitude pasture in the Italian Alps

The seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk was studied in a high altitude pasture in the Alps (1900 m a.s.l.). PCB contamination in vegetation shows a concentration peak in June, which is mainly interpreted as the consequence of a temporary PCB enrichment of the air layer above the ground due to net emission fluxes from the soil. A three compartment dynamic model was developed to test this hypothesis. The North/South enrichment factor in the vegetation was 1.5-1.6 for penta- and hexa-substituted congeners and 1.7 for hepta- and octa-PCBs, according to the effect of temperature on compounds having higher K(oa) values. Milk concentrations followed the vegetation seasonal trend. The congener abundance in milk is in agreement with the biotransformation susceptibility, absorption efficiency and residence time of the different congeners in dairy cows.

The Effect of the Organic Matter Composition on POP Accumulation in Soil

The effect of different humic fractions on polychlorinated biphenyl (PCB) contamination in soils was tested in the field by means of 53 soil samples from a high-altitude grassland plateau in the Italian Alps. Three humic fractions (humin, humic acids, and fulvic acids) were characterized in parallel by quantifying 12 PCB congeners to establish a direct relationship between PCB levels and humic fraction concentrations. Humin (the most hydrophobic fraction) appears to be the most closely correlated with the amount of PCBs in soil (R2 = 0.83), while fulvic acid shows the lowest correlation (R2 = 0.49). The idea of preferential sorption of hydrophobic compounds in the humin fraction is discussed, and the humin carbon content (fhuminC) is proposed as an improved parameter for evaluating the potential for POP accumulation in soils, replacing total organic carbon (foc). Congener studies revealed that penta- and hexa-substituted-CBs show the optimal combination of physicochemical properties for equilibrating with the humin content in soil. Moreover, fhuminC/foc is conceptually equivalent to the empirical coefficients used in predictive Ksa equations. In our samples, the fhuminC/foc was 0.55, a value in between the empirical coefficients proposed in the literature. In predictive equations, the use of fhuminC instead foc avoids the necessity of using an empirical parameter for a ‘generic’ condition by introducing an experimental parameter (fhuminC) that takes into account local conditions (organic matter composition).

Polybrominated diphenyl ether contamination in soil, vegetation, and cow milk from a high-mountain pasture in the Italian Alps.

This study investigates contamination by 13 polybrominated diphenyl ether (PBDE) congeners in a high-mountain pasture located in the Italian Alps. The trend of PBDE contamination in three soil layers was investigated by a spring–summer sampling period to understand the importance of different environmental variables, such as seasonality, topographical aspect, and soil features. We also evaluated PBDE accumulation in grasses covering the plateau, and because the study area has been used for a pasture for a long time, we measured PBDE levels in milk from grazing cows. Overall, we found moderate PBDE contamination in Andossi soils, with differences depending on the layer, mountain side, and organic matter content. The vegetation of the plateau had greater PBDE concentrations than the soils and showed a grass/soil accumulation ratio between 2 and 12, indicating that deposition from the atmosphere is actually the dominant process in this area. Last, PBDE concentrations in milk followed similar seasonal trends as the vegetation but showed variations in congener abundance in agreement with the biotransformation susceptibility, absorption efficiency, and residence time of different BDEs in dairy cattle.