Concentrations of PAHs,and nitro- and methyl- derivatives associated with a size-segregated urban aerosol

Size-segregated atmospheric particles were collected in Rome, Italy, using a low-pressure impactor.Twelve sampling campaigns were conducted under different meteorological conditions over a whole year covering 155 not consecutive days. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) and their nitro- and methyl- derivatives known for their toxicity. An assessment of the carcinogenic potency of the particles known to penetrate into lungs, liver, heart and nervous system was performed.The distribution of the classes of compounds was unimodal and centrated at 0.4 μm size fraction for PAHs and bimodal and centrated at 0.1 and 0.4 μm for methyl- and nitro- derivatives. The 18% of toxic organic compounds we analyzed was distributed into the ultrafine fraction (PM_0.1) and 76% in the fine fraction; but substituted PAH distribution in the ultrafine particles shifted toward higher values during warm periods. In July, the 50% of the total nitro-PAHs was found in PM_0.1 and an average of 42% of the total methyl-PAHs was found in the same fraction in summer and intermediate seasons.An evaluation of the potential toxicity of the measured compounds was tentatively assessed based on Potency Equivalency Factors (PEF).     

Finite population properties of individual predictors based on spatial patterns

In this study a conceptual framework for assessing the statistical properties of a non-stochastic spatial interpolator is developed through the use of design-based finite population inference tools. By considering the observed locations as the result of a probabilistic sampling design, we propose a standardized weighted predictor for spatial data starting from a deterministic interpolator that usually does not provide uncertainty measures. The information regarding the coordinates of the spatial locations is known at the population level and is directly used in constructing the weighting system. Our procedure captures the spatial pattern by means of the Euclidean distances between locations, which are fixed and do not require any further assessment after the sample has been drawn. The predictor for any individual value turns in a ratio of design-based random quantities. We illustrate the predictor design-based statistical properties, i.e. asymptotically p-unbiasedness and p-consistency, for simple random sampling without replacement. An application to a couple of environmental datasets is presented, for assessing predictor performances in correspondence of different population characteristics. A comparison with the equivalent non-spatial predictor is presented.     

Seasonal and pluri-annual variability of sediment accumulation and organic matter fluxes in the Northwestern Adriatic shelf and its relationship with the frontal system

Twenty eight short sediment cores, collected along six transects in two areas influenced by the frontal system formed by the Po River, were analysed for Th and Cs in order to improve our knowledge on short time scale sediment deposition, accumulation and mixing. Sedimentological and mineralogical parameters were also analysed._ The decreasing Cs activities and C/N values in surface sediments indicate a decreasing input of terrestrial material during the study period. Furthermore, low excess thorium activities and inventories at some sites, together with low sedimentary organic matter concentrations in the southern area, suggest that the productivity in summer 1997 was lower than in 1996. Temporal and spatial shifts of the front exert a strong influence on short time scale deposition of particulate matter in the northern area, while the front position is more stable in the southern area, influencing both seasonal and interannual deposition._ The comparison between apparent seasonal and pluri-annual accumulation rates suggests, for the northern area, a sedimentation pattern characterized by temporal deposition of material on to the sea floor, with periodical resuspension. The net apparent accumulation is 0.1-0.4 r g r cm r yr. The same occurs for the southern area, where values are higher, probably due to the longer persistence of the frontal system in the same area over the years. Here, both seasonal and pluri-annual deposition showed the same pattern, but seasonal values were two to three times higher with a net apparent accumulation rate of 0.3-0.8 r g r cm r yr. Organic carbon and nitrogen concentrations are generally less than 1.3 and 0.2% d.w., with lower values in the southern area. By contrast, mass fluxes showed higher values in the southern area, while the rate of removal over a pluri-annual time scale is generally high.     

Immunotoxicity in ascidians: Antifouling compounds alternative to organotins – II. The case of Diuron and TCMS pyridine

Using short-term hemocyte cultures of the colonial ascidian Botryllus schlosseri exposed to various sublethal concentrations of Diuron (3-(3,4-diclorophenyl)-1,1-dimethylurea) and TCMS pyridine (2,3,5,6-tetrachloro-4-(metylsulphonyl)pyridine), we evaluated their immunotoxic effects through a series of cytochemical assays previously used for organotin compounds. At concentrations higher than 250 μ M and 10 μ M for Diuron and TCMS pyridine, respectively, both biocides exerted immunosuppressant effects on Botryllus hemocytes, causing i) deep changes in the cytoskeleton that irreversibly affect cell morphology and phagocytosis, ii) induction of DNA damage, iii) leakage of oxidative and hydrolytic enzymes due to membrane alteration. Unlike organotin compounds, Diuron and TCMS pyridine do not inhibit cytochrome-c-oxidase, and only TCMS pyridine triggers oxidative stress. When co-present, they exert an antagonistic interaction on cytoskeletal components.