{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T08:59:21Z","timestamp":1770973161587,"version":"3.50.1"},"reference-count":73,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,4,13]],"date-time":"2021-04-13T00:00:00Z","timestamp":1618272000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Soil Systems"],"abstract":"<jats:p>There is an intense and continuous growth of the world population living in cities. This increase in population means an increase in car traffic, an increase in new constructions and an increase in the production of waste that translates into an intensive use of land, particularly in terms of soil contaminants. Among other environmental contaminants, toxic metals, such as lead (Pb), cadmium (Cd), nickel (Ni) and chromium (Cr) represent a public health problem. In this study the content of toxic metals in Lisbon\u2019s (Portugal) soils was determined. The study was conducted over approximately a decade in six city locations, with a total of about 700 samples. Each site has different urban characteristics: traffic zone, residential area, urban park and mixed areas. The study allowed to verify the heterogeneity of metal content values in the city soils and their dependence on local traffic. Metal contents were determined by graphite furnace atomic absorption spectroscopy (GFAAS). For each site the geo-accumulation index, pollution factor, degree of contamination, pollution load index and ecological risk factor were calculated. The mean concentrations of Cd, Cr, Ni and Pb in soils were 0.463, 44.0, 46.6 and 5.73 mg\/kg of dry soil, respectively. In the last year of the study the values were 0.417, 51.5, 62.4 and 8.49 mg\/kg of dry soil, respectively. Cd and Ni exceeded the typical content values of these metals in the earth\u2019s crust, indicating their anthropogenic origin. The correlation analysis revealed a significant correlation between Cr and Ni, Cd and Ni and Cd and Pb contents in the city soils. Regarding the results obtained in this long monitoring campaign, Lisbon\u2019s soils can be considered as having low levels of pollution by these metals.<\/jats:p>","DOI":"10.3390\/soilsystems5020027","type":"journal-article","created":{"date-parts":[[2021,4,13]],"date-time":"2021-04-13T05:31:37Z","timestamp":1618291897000},"page":"27","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":64,"title":["Heavy Metals Contamination of Urban Soils\u2014A Decade Study in the City of Lisbon, Portugal"],"prefix":"10.3390","volume":"5","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1585-9099","authenticated-orcid":false,"given":"Hugo F\u00e9lix","family":"Silva","sequence":"first","affiliation":[{"name":"ISEL-ADEQ, \u00c1rea Departamental de Engenharia Qu\u00edmica do Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Em\u00eddio Navarro, 1, 1059-007 Lisboa, Portugal"},{"name":"Centro de Qu\u00edmica Estrutural, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal"},{"name":"CIEQB, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Em\u00eddio Navarro, 1, 1059-007 Lisboa, Portugal"}]},{"given":"Nelson Frade","family":"Silva","sequence":"additional","affiliation":[{"name":"ISEL-ADEQ, \u00c1rea Departamental de Engenharia Qu\u00edmica do Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Em\u00eddio Navarro, 1, 1059-007 Lisboa, Portugal"},{"name":"Centro de Qu\u00edmica Estrutural, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal"},{"name":"CIEQB, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Em\u00eddio Navarro, 1, 1059-007 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9735-9332","authenticated-orcid":false,"given":"Cristina Maria","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Centro de Qu\u00edmica Estrutural, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5240-8070","authenticated-orcid":false,"given":"Manuel Jos\u00e9","family":"Matos","sequence":"additional","affiliation":[{"name":"ISEL-ADEQ, \u00c1rea Departamental de Engenharia Qu\u00edmica do Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Em\u00eddio Navarro, 1, 1059-007 Lisboa, Portugal"},{"name":"CIEQB, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Em\u00eddio Navarro, 1, 1059-007 Lisboa, Portugal"},{"name":"IT, Instituto de Telecomunica\u00e7\u00f5es, IST, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/S0169-2046(03)00026-4","article-title":"Landscape change and the urbanization process in Europe","volume":"67","author":"Antrop","year":"2004","journal-title":"Landsc. 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