Correction to: Chemical characterization of atmospheric particulate matter in Friuli Venezia Giulia (NE Italy) by exploratory data analysis with multisite and multivariate approach.

Unfortunately, we encountered an error with units of measure in reporting data in the last two columns of Table 3 (on page 28814 in the printed version), so that those data should be changed as reported in the following corrected version of the Table.

Chemical characterization of atmospheric particulate matter in Friuli Venezia Giulia (NE Italy) by exploratory data analysis with multisite and multivariate approach.

The chemical composition of atmospheric particulate (PM10) in the Friuli Venezia Giulia (FVG) region (NE Italy) has been characterized for the first time with the help of exploratory data analysis (EDA) techniques (uni-, bi-, and multivariated, i.e., principal components analysis), molecular and elemental diagnostic ratios, and seasonal trends. Despite that the available analytical data was limited to the parameters routinely analyzed on PM10 by ARPA FVG (11 elements and 16 PAH congeners), the large number of samples and of measured chemical parameters, together with the applied techniques of data analysis, allowed us to extract useful latent information from the dataset, resulting in a greater knowledge of both regional and local features. Specifically, we succeeded in matching data patterns to the known pollution sources of some sampling stations, both industrial (two secondary fusion steelworks and one coke oven) and urban (traffic and domestic heating), and in defining the mainly urban or mainly industrial feature of some questionable sampling stations. This is of paramount importance to check for possible industrial inputs in urban stations, allowing policymakers to implement the most appropriate response.

Anthropogenic loads and biogeochemical role of urea in the Gulf of Trieste.

In order to assess the role of urea in the Gulf of Trieste, oceanographic data collected from 2002 to 2011 were analyzed together with ancillary ambient information and compared to past studies. The recent levels of urea found in these coastal waters (median = 1.1 µM N, maximum value = 19.7 µM N) are often high and similar to those reported in the early 1980s. A preliminary estimate of the external inputs indicated that this enrichment in urea is mainly due to emissions from urban sewage systems, whereas the contributions of rivers and atmospheric deposition are scarce. As a consequence, urea appears to be a reliable tracer of the diffusion of wastewaters in the coastal marine environment, more specific and sensitive than other nutrients, with a behavior that also reflects the technology of the treatment plants. The stability of urea levels over the last three decades suggests that the upgrade of wastewater treatment technologies was probably balanced by the concomitant increase of the anthropogenic pressure in the area (477,000 to 1,300,000 inhabitant equivalent). Budget estimates on the gulf-wide scale indicate that urea (177-530 t N) is not negligible compared to dissolved inorganic nitrogen (409-919 t N) and that it can constitute up to 56% of the nitrogen available for plankton growth. A large accumulation of urea can occur during summer periods characterized by stable weather conditions and weak circulation, whereas a biologically mediated degradation to ammonium is observed in autumn in concomitance to a strong shift of the marine ecosystem toward heterotrophic conditions. These processes, together with a potential competition between phytoplankton and bacteria for the utilization of this nitrogen form, suggest that the biogeochemical role of urea should be better investigated in mid-latitude coastal zones subjected to highly variable ambient conditions and to overloads of this compound.

Urban BTEX Spatiotemporal Exposure Assessment by Chemometric Expertise.

Normative regulations on benzene in fuels and urban management strategies are expected to improve air quality. The present study deals with the application of self-organizing maps (SOMs) in order to explore the spatiotemporal variations of benzene, toluene, ethylbenzene, and xylene levels in an urban atmosphere. Temperature, wind speed, and concentration values of these four volatile organic compounds were measured after passive sampling at 21 different sampling sites located in the city of Trieste (Italy) in the framework of a multi-year long-term monitoring program. SOM helps in defining pollution patterns and changes in the urban context, showing clear improvements for what concerns benzene, toluene, ethylbenzene, and xylene concentrations in air for the 2001-2008 timeframe.