Abstract
Background, aim, and scope
Diffuse soil contamination has often been neglected in scientific literature, as most studies focus on contaminants from point-sources (either of industrial or agricultural origin). However, soil pollution from diffuse sources is recognized as one of the major soil threats by the EU Soil Thematic Strategy. In fact, some pollutants are nowadays ubiquitarious in the soil system, and they have to be considered for the implementation of environmental legislation, the definition of clean-up values in remediation activities and, more generally, for a sustainable management of rural areas. In the literature large scale studies on diffuse contamination are few and scattered and often do not consider a wide range of contaminants, the effect of land use, the vertical variability and the potential natural contribution. Aim of this work was to provide an overview of the diffuse soil contamination on a regional scale for a large set of contaminants. Soil inorganic (Cd, Cr, Ni, Pb, Cu, Zn) and organic contaminants (polychlorinated dibenzo-p-dioxins(PCDD), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) as well as other soil general parameters were investigated on a 18 × 18 km grid covering a whole Italian region heavily industrialized and intensively cultivated. Soils were sampled at different depths both for natural–undisturbed soil and for agricultural–plow soil. Differences in the trends of investigated contaminants, as a consequence of land use, vertical variability, natural or geogenic origin, relationships among contaminants, and with main soil properties, were explored by means of enrichment factors, bi- and multi-variate statistics.
Materials and methods
The sampling scheme of this study is based on a systematic 18 × 18 km grid covering the whole region. Overall, 43 monitoring sites located at the center of each cell were sampled. At each site, five individual core samples within a 10 × 10 m area were taken at different depths for natural–undisturbed soil (topsoil 0–10 cm, subsoil 10–30 cm) and for agricultural–plow soil (topsoil Ap horizon, subsoil 20 cm below the Ap lower limit). Samples were processed for general soil properties as well as for organic (PAHs, PCBs, PCDDs/dibenzofurans (DFs)) and inorganic (Cd, Cr, Ni, Pb, Cu, Zn) contaminants analyses (aqua regia digestions). Contaminants were detected after extraction by means of ICP-MS and GC-MS. Statistical analysis was conducted using the software SPSS 13 (SPSS) and Minitab 15 (MINITAB). Data were geographically managed and processed with the Arcview 3.2 (ESRI, CA, USA) GIS software.
Results
Organic contaminants such as PCDDs were found to accumulate in natural areas while inorganics mostly concentrate in agricultural soils, confirming the presence of important phenomena of long-range diffuse contamination for the first and short-range for the latter. Soil use was also confirmed to be a major parameter in influencing the type, degree, and distribution of contaminants. Vertical variability was found to be high for organic contaminants and for Pb, suggesting their main anthropogenic origin, while other elements such as Cr and Ni appeared to be more related to the natural background. Data were compared with those from soils of a large industrial city present in the area, confirming the strong enrichment of the urban environment with respect to some contaminants such as metals, PCBs, and PAHs. Other contaminants such as PCDD/DFs showed lower differences, confirming their diffuse and almost ubiquitarious pollution.
Discussion and conclusions
Even if natural soils in this study are mostly located far from major sources of contamination, notable differences appeared when compared to agricultural areas. In particular, the enrichment in the concentrations of organic contaminants such as PCDDs in natural areas and of inorganics in agricultural soils confirm the presence of important phenomena of long-range diffuse contamination for the first and short-range for the latter, which appeared also to be related to agricultural activities. Contaminants like PCDDs, PCBs, PAHs, and Pb presented high vertical variability, confirming their anthropogenic origin and strong affinity to soil organic matter, while others appear to be more related to the natural background. The comparison of data with those from soils within a large-industrial city present in the study area confirms the strong enrichment of the urban environment with respect to some contaminants such as metals, PCBs, and PAHs. Other contaminants such as PCDD/DFs showed lower differences confirming their diffuse and ubiquitarious pollution.
Recommendations and perspectives
Soil diffuse contamination revealed to be an important source for some contaminants that appear to distribute over a large scale. The type of land use strongly influences the distribution of pollutants in soils, by diluting them in depth (plowing in agricultural areas) or concentrating contaminants in the surface (natural areas or meadows). Data provided in this study constitute an important dataset of the soil environmental quality on a large scale that can be used for the development of guidelines for soil management, the definition of local clean-up values, and the implementation of risk assessment procedures.
Similar content being viewed by others
References
Biasioli M, Ajmone-Marsan F (2007) Organic and inorganic diffuse contamination in urban soils: the case of Torino (Italy). J Environ Monit 9:862–868
Biasioli M, Barberis R, Ajmone-Marsan F (2006) The influence of a large city on some soil properties and metals content. Sci Total Environ 356:154–164
Boruvka L, Vacek O, Jehlicka J (2005) Principal component analysis as a tool to indicate the origin of potentially toxic elements in soils. Geoderma 128:289–300
Cousins IT, Jones KC (1998) Air-soil exchange of semi-volatile organic compounds (Socs) in the UK. Environ Pollut 102:105–118
Cousins IT, Beck AJ, Jones KC (1999) A review of the processes involved in the exchange of semi-volatile organic compounds (Svoc) across the air-soil interface. Sci Total Environ 228:5–24
European Commission (2006) Thematic Strategy for Soil Protection. COM(2006)231 final, 22.9.2006. Brussels, Belgium
European Community (2003) The Lucas survey—European statisticians monitor territory. Updated edition June 2003, Office for official Publications of the European Communities. Luxembourg 2000:110–122
Facchinelli A, Sacchi E, Mallen L (2001) Multivariate statistical and gis-based approach to identify heavy metal sources in soils. Environ Pollut 114:313–324
Kabata-Pendias A, Pendias H (1992) Trace elements in soils and plants, 2nd edn. CRC, Boca Raton
Katsoyiannis A, Samara C (2004) Persistent organic pollutants (Pops) in the sewage treatment plant of Thessaloniki, Northern Greece: occurrence and Removal. Water Res 38:2685–2698
Lombini A, Dinelli E, Ferrari C, Simoni A (1998) Plant–soil relationships in the serpentinite screes of Mt. Prinzera (Northern Apennines, Italy). J Geochem Explor 64(1–3):19–33
Lopez-Mosquera ME, Barros R, Sainz MJ, Carral E, Seoane S (2005) Metal concentrations in agricultural and forestry soils in Northwest Spain: implications for disposal of organic wastes on acid soils. Soil Use Manage 21:298–305
Masih A, Taneja A (2006) Polycyclic aromatic hydrocarbons (PAHs) concentrations and related carcinogenic potencies in soil at a semi-arid region of India. Chemosphere 65:449–456
Mico C, Recatala L, Peris A, Sanchez J (2006) Assessing heavy metal sources in agricultural soils of an European Mediterranean area by multivariate analysis. Chemosphere 65:863–872
Mipaf (1999) Metodi di analisi chimica del suolo. Franco Angeli, Milan
Nadal M, Schuhmacher M, Domingo JL (2004) Levels of PAHs in soil and vegetation samples from Tarragona County, Spain. Environ Pollut 132:1–11
Shi JC, Wang HZ, Xu JM, Wu JJ, Liu XM, Zhu HP, Yu CL (2007) Spatial distribution of heavy metals in soils: a case study of Changxing, China. Environ Geol 52:1–10
Srogi K (2007) Monitoring of environmental exposure to polycyclic aromatic hydrocarbons: a review. Environ Chem Lett 5:169–195
Sweetman AJ, Dalla Valle M, Prevedouros K, Jones KC (2005) The role of soil organic carbon in the global cycling of persistent organic pollutants (POPs): interpreting and modeling field data. Chemosphere 60:959–972
Tremolada P, Villa S, Bazzarin P, Bizzotto E, Comolli R, Vighi M (2008) Pops in mountain soils from the Alps and Andes: suggestions for a ‘precipitation effect’ on altitudinal gradients. Water Air Soil Pollut 188:93–109
Van Den Berg M, Birnbaum L, Bosveld ATC, Brunstrom B, Cook P, Feeley M, Giesy JP, Hanberg A, Hasegawa R, Kennedy SW, Kubiak T, Larsen JC, Van Leeuwen FXR, Liem AKD, Nolt C, Peterson RE, Poellinger L, Safe S, Schrenk D, Tillitt D, Tysklind M, Younes M, Waern F, Zacharewski T (1998) Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife. Environ Health Persp 106:775–792
Wania F, Mclachlan MS (2001) Estimating the influence of forests on the overall fate of semivolatile organic compounds using a multimedia fate model. Environ Sci Technol 35:582–590
Weber J, Karczewska A (2004) Biogeochemical processes and the role of heavy metals in the soil environment. Geoderma 122:105–107
Zhang CS (2006) Using multivariate analyses and gis to identify pollutants and their spatial patterns in urban soils in Galway, Ireland. Environ Pollut 142:501–511
Acknowledgements
The help of ARPA Piemonte, Polo Bonifiche of Alessandria, with the analytical work is gratefully acknowledged.
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible editor: Ravi Naidu
Rights and permissions
About this article
Cite this article
Fabietti, G., Biasioli, M., Barberis, R. et al. Soil contamination by organic and inorganic pollutants at the regional scale: the case of Piedmont, Italy. J Soils Sediments 10, 290–300 (2010). https://doi.org/10.1007/s11368-009-0114-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11368-009-0114-9