A new approach to assess the degree of contamination and determine sources and risks related to PTEs in an urban environment: the case study of Santiago (Chile).

In 2017, a geochemical survey was carried out across the Commune of Santiago, a local administrative unit located at the center of the namesake capital city of Chile, and the concentration of a number of major and trace elements (53 in total) was determined on 121 topsoil samples. Multifractal IDW (MIDW) interpolation method was applied to raw data to generate geochemical baseline maps of 15 potential toxic elements (PTEs); the concentration-area (C-A) plot was applied to MIDW grids to highlight the fractal distribution of geochemical data. Data of PTEs were elaborated to statistically determine local geochemical baselines and to assess the spatial variation of the degree of soil contamination by means of a new method taking into account both the severity of contamination and its complexity. Afterwards, to discriminate the sources of PTEs in soils, a robust Principal Component Analysis (PCA) was applied to data expressed in isometric log-ratio (ilr) coordinates. Based on PCA results, a Sequential Binary Partition (SBP) was also defined and balances were determined to generate contrasts among those elements considered as proxies of specific contamination sources (Urban traffic, productive settlements, etc.). A risk assessment was finally completed to potentially relate contamination sources to their potential effect on public health in the long term. A probabilistic approach, based on Monte Carlo method, was deemed more appropriate to include uncertainty due to spatial variation of geochemical data across the study area. Results showed how the integrated use of multivariate statistics and compositional data analysis gave the authors the chance to both discriminate between main contamination processes characterizing the soil of Santiago and to observe the existence of secondary phenomena that are normally difficult to constrain. Furthermore, it was demonstrated how a probabilistic approach in risk assessment could offer a more reliable view of the complexity of the process considering uncertainty as an integral part of the results.

Assessment of the concentrations of polycyclic aromatic hydrocarbons and organochlorine pesticides in soils from the Sarno River basin, Italy, and ecotoxicological survey by Daphnia magna.

We studied the contamination level of the soils of the Sarno River basin in southwestern Italy by combined acute toxicity test with Dapnia magna and chemical extraction of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). For the ecotoxicological assessment, 188 samples were taken and coincided with those of a previous study (2013) where heavy metals were surveyed. For the organics assessment, 21 samples were selected nearby representative areas of elevated anthropic pressure. About 10.1 % of the samples showed noticeable sign of D. magna mortality, 61-100 %, and fall along the potentially floatable areas of Sarno and Solofrana basins with high degree of contamination by Cr, As, Zn, and Hg. High levels of ecotoxicity, 61-100 %, were determined in the lower Sarno River basin in areas of moderate or low degree of contamination by Cd, Cu Hg, Pb, Sb, Sn, and Zn. Benzo(a)pyrene, indenopyrene, and benzo(g,h,i)perylene were present at concentrations of 0.32, 0.23, and 0.18 mg kg(-1), respectively, 2- to 3-fold the law limits with most of the samples falling nearby the points where the ecotoxicity output was close to 100 %. Among OCPs, pp'-DDT had a mean of 0.225 mg kg(-1) and hence about more than 200- and 2-fold the residential, 0.01 mg kg(-1), and commercial/industrial limits, 0.1 mg kg(-1) and determined mainly in the central Sarno valley in an area where elevated concentrations of benzopyrene and D. magna mortality were also observed. The study evidenced the high rate of contamination by PAHs and OCPs of the soils and the need of urgent remediation actions.

Polycyclic aromatic hydrocarbons in the soils of a densely populated region and associated human health risks: the Campania Plain (Southern Italy) case study.

Polycyclic aromatic hydrocarbons (PAHs) are a major class of environmental pollutants mainly arising from anthropogenic activities. In this paper, the behavior and the distribution patterns of sixteen PAHs, listed as priority pollutants by the United States Environmental Protection Agency, were evaluated in 119 soil samples collected in different areas of Campania region in the southern Italy. The observation of the geochemical distribution patterns showed that both high and low molecular weight PAHs are mostly concentrated within the metropolitan area of Naples, the Agro Aversano area, and, partly, the Sarno River basin. In accordance with the Italian environmental law (D. Lgs. 152/2006), these areas should be considered potentially contaminated and not suitable for a residential use unless an environmental risk analysis does not demonstrate their safety. As a consequence, a preliminary quantitative risk assessment enhanced by the use of GIS was run revealing the existence of an incremental lifetime cancer risk higher than 1 × 10(-5) for the city of Naples and for some other populous areas.