Papers by Antonio Di Guardo
In this paper a study relevant to the distribution of three chemical substances in a river is aff... more In this paper a study relevant to the distribution of three chemical substances in a river is afforded. The unsteady flow and the distributions of the pollutants are calculated by means of a deterministic model so that the concentration values can be evaluated in any point of the space-time domain. The numerical approach followed and the code in which it is implemented are computationally cost-effectiveness respect the stability and the accuracy properties and by means of them it is possible to foresee the evolution of the concentrations of chemical compounds.
Environmental Science & Technology, 1996
Environmental Science & Technology, 1994
Pine needles have been demonstrated as a useful monitoring matrix for the evaluation of the tropo... more 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 ...
Ecological Applications, 1995
ABSTRACT The authors of this article agree with many of the arguments against a complete ban on o... more ABSTRACT The authors of this article agree with many of the arguments against a complete ban on organochlorines, but they suggest that certain key point require greater emphasis and some are open to question. Because social responses are involved, it is useful first to clarify how organochlorines (OC) are generated by society and how they are or can be regulated. Discussion includes the following topics: OC synthesis: by design and by accident; partitioning and bioaccumulation; causes of hydrophobicity; known bioaccumulative OCs; social decisions on Chlorine. 10 refs. 1 fig.
Chemosphere, 2003
Needles of two conifer species, Picea abies and Pinus nigra, were used as passive samplers for mo... more Needles of two conifer species, Picea abies and Pinus nigra, were used as passive samplers for monitoring air contamination by sampling at increasing distances from a suspected point source of DDT. Needle concentrations declined with increasing distance downwind of the point source allowing to identify spatial and temporal trends of accumulation. This suggested that conifer needles are effective biomonitors of contamination levels in areas characterized by the presence of semi-volatile substances. Differences in uptake were apparent between the species. Needle morphology and structure were studied with scanning electron microscope (SEM) as were dimensional parameters (surface area, volume). The results suggest that the concentrations depend on a mechanism involving the inner structure of the needles, specifically the number and accessibility of resin channels rather than their surface area. Pine needles have more channels with greater accessibility than spruce. The results suggest that spruce is more suitable for short term measurement while pine for determining long term cumulative exposure.
Pharmaceuticals in the Environment, 2008
Environmental Pollution, 2014
A spatially-explicit version of the recent multimedia fate model SoilPlus was developed and appli... more A spatially-explicit version of the recent multimedia fate model SoilPlus was developed and applied to predict the runoff of three pesticides in a small agricultural watershed in north-eastern Italy. In order to evaluate model response to increasing spatial resolution, a tiered simulation approach was adopted, also using a dynamic model for surface water (DynA model), to predict the fate of pesticides in runoff water and sediment, and concentrations in river water. Simulation outputs were compared to water concentrations measured in the basin. Results showed that a high spatial resolution and scenario complexity improved model predictions of metolachlor and terbuthylazine in runoff to an acceptable performance (R 2 ¼ 0.64e0.70). The importance was also shown of a field-based database of properties (i.e. soil texture and organic carbon, rainfall and water flow, pesticides half-life in soil) in reducing the distance between predicted and measured surface water concentrations and its relevance for risk assessment.
Journal of Environmental Monitoring, 2007
Forests were shown to play an important role in influencing atmospheric concentrations and transp... more Forests were shown to play an important role in influencing atmospheric concentrations and transport of persistent organic pollutants (POPs) in the environment. World forests cover more than 4 billion hectares and contain up to 80% of the above ground organic carbon. Given the lipophilic nature of POPs, this suggests that forests can influence the environmental fate of POPs at a global scale. POP accumulation in forest canopies still presents points of concern given the complexity of these ecosystems. In particular, the role of ecological parameters such as LAI (leaf area index) and SLA (specific leaf area) and their dynamics during the growing season was not sufficiently investigated yet. This paper reviews, compares and interprets a unique case study in which air and leaf concentrations and deposition fluxes for selected polychlorinated biphenyls (PCBs) were measured in three different forest types exposed to the same air masses. In order to trace the air-leaf-soil path of these compounds, a dynamic model of POP accumulation into forest canopy was applied. The dynamics of the canopy biomass strongly affected the trend of leaf concentration with time. Growth dilution effect can prevent the more chlorinated compounds from reaching the partitioning equilibrium before litter fall, while the more volatile compounds can approach equilibrium in the range of few weeks. An amount of up to 60 ng of PCBs per square metre of ground surface was predicted to be stored in each of the selected forests at fully developed canopy. Dry gaseous deposition fluxes to forest canopy were estimated to reach a maximum value of about 0.5-1.5 ng m(-2) d(-1) during the spring period.
Science of The Total Environment, 2014
Falling snow acts as an efficient scavenger of contaminants from the atmosphere and, accumulating... more Falling snow acts as an efficient scavenger of contaminants from the atmosphere and, accumulating on the ground surface, behaves as a temporary storage reservoir; during snow aging and metamorphosis, contaminants may concentrate and be subject to pulsed release during intense snow melt events. In high-mountain areas, firn and ice play a similar role. The consequent concentration peaks in surface waters can pose a risk to high-altitude ecosystems, since snow and ice melt often coincide with periods of intense biological activity. In such situations, the role of dynamic models can be crucial when assessing environmental behavior of contaminants and their accumulation patterns in aquatic organisms. In the present work, a dynamic fate modeling approach was combined to a hydrological module capable of estimating water discharge and snow/ice melt contributions on an hourly basis, starting from hourly air temperatures. The model was applied to the case study of the Frodolfo glacier-fed stream (Italian Alps), for which concentrations of a number of persistent organic pollutants (POPs), such as polychlorinated biphenyl (PCBs) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) in stream water and four macroinvertebrate groups were available. Considering the uncertainties in input data, results showed a satisfying agreement for both water and organism concentrations. This study showed the model adequacy for the estimation of pollutant concentrations in surface waters and bioaccumulation in aquatic organisms, as well as its possible role in assessing the consequences of climate change on the cycle of POPs.
Environmental Science & Technology, 2000
Environmental Science and Pollution Research, 1994
A validation exercise of the SoilFug model using field runoff data from Rosemaund Farm (UK) is de... more A validation exercise of the SoilFug model using field runoff data from Rosemaund Farm (UK) is described. A comparison has been made of modelled and measured concentrations of several pesticides in surface water and soil during and after specific rain events following application. The field experiments were designed to obtain data on rainfall, outflows of water, pesticide application rates and concentrations in soil and water. The results were satisfactory for the undissociated pesticides (atrazine, carbofuran, dimethoate, isoproturon, lindane, simazine and trifluralin), whose concentrations in water were mostly predicted within an order of magnitude of measured data. The results for the dissociated pesticides (dichlorprop, MCPA, mecoprop) were less satisfactory, giving generally much higher predicted concentrations in water. The use of the SoilFug model is suggested for the calculation of predicted environmental concentrations (PECs) in water, since it generally produces acceptable results from a relatively small set of input data, most of which is generally available.
Environmental Science & Technology, 2008
Polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in air and surface seawater ... more Polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in air and surface seawater between 49°N and 25°S in the open Atlantic Ocean. Elevated concentrations of PAHs (Σ 10 PAHs ≈1.4-2.5 ng m -3 air, and 0.7-1 ng L -1 seawater) occurred in the Biscay Bay and off the northwest coast of Africa. The unexpectedly high concentrations off NW Africa were discussed assessing the possible contribution of the emerging oil industry along the African shore, the role of biomass burning and natural sources of PAHs. In the southern Atlantic, concentrations of PAHs were close to detection limits (Σ 10 PAHs ≈ 0.02-0.5 ng m -3 air, and 0.06-0.5 ng L -1 seawater) and showed decreasing trends with increasing latitudes. Correlations of PAHs' partial pressures versus inverse temperature were not significant, in contrast to results for polychlorinated biphenyls from the same transect. This could have been due to the importance of ongoing primary sources and the shorter atmospheric life-times of PAHs. Air-water fugacity ratios (f a /f w ) were calculated for selected compounds. They were close to 1 for fluoranthene and pyrene in remote open ocean areas suggesting air-water partitioning near equilibrium. Ratios for anthracene and phenanthrene were <0.3 in the remote tropical Atlantic, suggesting net volatilization.
articles by Antonio Di Guardo
The partitioning tendency of chemicals, in this study pesticides in particular, into different en... more The partitioning tendency of chemicals, in this study pesticides in particular, into different environmental compartments depends mainly on the concurrent relevance of the physico-chemical properties of the chemical itself. To rank the pesticides according to their distribution tendencies in the different environmental compartments we propose a multivariate approach: the combination, by principal component analysis, of those physico-chemical properties like organic carbon partition coefficient (Koc), n-octanol/water partition coefficient (Kow), water solubility (Sw), vapour pressure and Henry's law constant (H) that are more relevant to the determination of environmental partitioning. The resultant macrovariables, the PC1 and PC2 scores here named leaching index (LIN) and volatality index (VIN), are proposed as preliminary environmental partitioning indexes in different media. These two indexes are modeled by theoretical molecular descriptors with satisfactory predictive power. Such an approach allows a rapid pre-determination and screening of the environmental distribution of pesticides starting only from the molecular structure of the pesticide, without any a priori knowledge of the physico-chemical properties.
The environmental behaviour of global organic contaminants is known to be controlled by the physi... more The environmental behaviour of global organic contaminants is known to be controlled by the physico-chemical properties of the compounds themselves. The principal component analysis of some physico-chemical properties, particularly relevant in determining mobility potential (vapour pressure, Henry's law constant, water solubility, K(OW), K(OA) and melting point) allows a multivariate approach to a ranking of organic pollutants according to their intrinsic tendency towards mobility, and the definition of four a priori mobility classes for screening purposes. Quantitative structure-property relationships (QSPRs) were used to predict missing values for octanol/air partition coefficients. Finally, a classification method employing theoretical molecular descriptors was used to assign studied chemicals to four mobility classes. The proposed approach assesses, directly and simply, a pollutant's inherent tendency towards mobility using only knowledge of the pollutant's molecular structure; the approach is particularly useful for a preliminary screening and the prioritisation of organic pollutants of emerging environmental concern.
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Papers by Antonio Di Guardo
articles by Antonio Di Guardo