{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,27]],"date-time":"2026-04-27T22:53:10Z","timestamp":1777330390805,"version":"3.51.4"},"reference-count":61,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2018,1,2]],"date-time":"2018-01-02T00:00:00Z","timestamp":1514851200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Geosciences"],"abstract":"<jats:p>The focus area is located along Beja and Faro districts (southwestern of Portugal), where the Baixo Alentejo Flysch Group exists, is composed of the M\u00e9rtola, Mira, and Brejeira Formations. The aim of this article is to characterize the groundwater contamination by toluene, one of the petroleum products that may originate from natural petroleum systems and have been introduced into the environment by natural seepage. For this study, twenty soil samples and thirty-one water samples were collected, in 2016, from artesian wells, boreholes, and springs, and analyzed in a GC-FID system. Sampling was performed using headspace vials, with distilled water and a bactericide to inhibit any bacterial activities. The results showed that 93.5% of water samples range between 1000 and 6000 \u03bcg\/L, and 55% are higher than 3000 \u03bcg\/L of toluene concentration. In soil samples, amounts of toluene are less than 1000 \u03bcg\/L in general. These levels are much higher than the World Health Organization health-based guideline for drinkable water (700 \u03bcg\/L) and higher than those usually found in other places, being only comparable with values from severe industrial contamination. Contaminated groundwater represents a serious concern for human health, and residents should be informed to avoid drinking contaminated ground water or using it for other domestic proposes.<\/jats:p>","DOI":"10.3390\/geosciences8010009","type":"journal-article","created":{"date-parts":[[2018,1,3]],"date-time":"2018-01-03T12:00:06Z","timestamp":1514980806000},"page":"9","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Groundwater Natural Contamination by Toluene in Beja and Faro Districts, Portugal"],"prefix":"10.3390","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7971-6196","authenticated-orcid":false,"given":"Gabriel","family":"Barberes","sequence":"first","affiliation":[{"name":"Department of Earth Science and Center of Geoscience, Faculty of Science and Technology, University of Coimbra, Largo Marqu\u00eas de Pombal, 3000-272 Coimbra, Portugal"},{"name":"Centre for Earth and Space Research of the University of Coimbra, Sta Clara, 3040-004 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8033-3486","authenticated-orcid":false,"given":"Rui","family":"Pena dos Reis","sequence":"additional","affiliation":[{"name":"Department of Earth Science and Center of Geoscience, Faculty of Science and Technology, University of Coimbra, Largo Marqu\u00eas de Pombal, 3000-272 Coimbra, Portugal"}]},{"given":"Andr\u00e9","family":"Spigolon","sequence":"additional","affiliation":[{"name":"Petrobras\/CENPES, Geochemistry Division, 21941-915 Rio de Janeiro, Brazil"}]},{"given":"Paulo","family":"Fonseca","sequence":"additional","affiliation":[{"name":"GeoFCUL\u2014Department of Geology at Sciences Faculty of Lisbon &amp; IDL\u2014Instituto Dom Luiz 15, Campo Grande, 1749-016 Lisbon, Portugal"}]},{"given":"Carlos","family":"Bandeira de Mello","sequence":"additional","affiliation":[{"name":"Petrobras\/CENPES, Geochemistry Division, 21941-915 Rio de Janeiro, Brazil"}]},{"given":"Maria","family":"Barata","sequence":"additional","affiliation":[{"name":"Centre for Earth and Space Research of the University of Coimbra, Sta Clara, 3040-004 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2018,1,2]]},"reference":[{"key":"ref_1","unstructured":"Agency for Toxic Substances and Disease Registry (ATSDR) (2017). 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