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Assessment of human exposure to environmental heavy metals in soils and bryophytes of the central region of Portugal

This study intends to identify the spatial patterns of variation for some metals and metalloids, in soils and mosses, in the central region of Portugal. The purposes were: (i) to identify relationships amongst five elements (Cu, Pb, Zn, Cr and As) in
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   PLEASE SCROLL DOWN FOR ARTICLE This article was downloaded by: [B-on Consortium - 2007]  On: 11 March 2010  Access details: Access Details: [subscription number 919435512]  Publisher Taylor & Francis  Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK International Journal of Environmental Health Research Publication details, including instructions for authors and subscription information:http://www.informaworld.com/smpp/title~content=t713425582 Assessment of human exposure to environmental heavy metals in soils andbryophytes of the central region of Portugal Amélia Paula Reis a ; Carla Patinha a ; Eduardo Ferreira da Silva a ; António Sousa b ; Rui Figueira c ;Cecilia Sérgio d ; Vera Novais da  Department of Geosciences, University of Aveiro, Aveiro, Portugal b  Technical Superior Institute,Lisbon, Portugal c  CERENA-IST, Lisbon, Portugal d  Botanical Garden, Natural History NationalMuseum, Lisbon, PortugalFirst published on: 16 February 2010 To cite this Article  Reis, Amélia Paula, Patinha, Carla, Ferreira da Silva, Eduardo, Sousa, António, Figueira, Rui, Sérgio,Cecilia and Novais, Vera(2010) 'Assessment of human exposure to environmental heavy metals in soils and bryophytesof the central region of Portugal', International Journal of Environmental Health Research, 20: 2, 87 — 113, Firstpublished on: 16 February 2010 (iFirst) To link to this Article DOI 10.1080/09603120903394649 URL http://dx.doi.org/10.1080/09603120903394649 Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdfThis article may be used for research, teaching and private study purposes. Any substantial orsystematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply ordistribution in any form to anyone is expressly forbidden.The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date. The accuracy of any instructions, formulae and drug dosesshould be independently verified with primary sources. The publisher shall not be liable for any loss,actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directlyor indirectly in connection with or arising out of the use of this material.  Assessment of human exposure to environmental heavy metals insoils and bryophytes of the central region of Portugal Ame ´lia Paula Reis a *, Carla Patinha a , Eduardo Ferreira da Silva a , Anto ´nio Sousa b ,Rui Figueira c , Cecilia Se ´rgio d and Vera Novais d a Department of Geosciences, University of Aveiro, Aveiro, Portugal;  b Technical SuperiorInstitute, Lisbon, Portugal;  c CERENA-IST, Lisbon, Portugal;  d  Botanical Garden, Natural History National Museum, Lisbon, Portugal  ( Received 17 April 2009; final version received 14 September 2009 )This study intends to identify the spatial patterns of variation for some metalsand metalloids, in soils and mosses, in the central region of Portugal. Thepurposes were: (i) to identify relationships amongst five elements (Cu, Pb, Zn,Cr and As) in three different media (topsoil, bottom soil and bryophytes) andwith some site-specific characteristics, using Multiple Correspondence Analysis;(ii) to define spatial patterns of variation for the associations identified byMultiple Correspondence Analysis using Variography and Ordinary Kriging;and (iii) to assess atmospheric deposition as a source of heavy metals to thetopsoil by crossing results with the biomonitors. The results indicated relativelylow metal concentrations in soils and mosses. Some metal associations anddissociations were identified. The spatial patterns of variation of bottom andtopsoil are distinct. There is some evidence that different site-specificcharacteristics control the spatial distribution of different elements. The areaswithin the central region of Portugal with a higher vulnerability to metalcontamination were identified. Keywords:  soils; bryophytes; heavy metals; site-specific characteristics; spatialdistribution Introduction Currently, the management of contaminated soils is a major concern. Numerouschemical compounds, organic and inorganic, reach the soils through differentpathways, either through atmospheric deposition or industrial spills/leaks, miningactivities, urban residues, etc. (Kelly et al. 1996; Ferreira da Silva et al. 2004; Wongand Li 2004). Such compounds are usually toxic and consequently it becomesnecessary to assess the adverse impacts to the environment and human health, theextent and magnitude of the risk posed by such chemicals, and what clean-up goalsare required for the soils. Among these hazardous chemicals, broadly specified andlegislated by several international entities, heavy metals (HMs) are toxic tohumans, especially for children, as well as animals (Ljung et al. 2006; Wong et al.2006). Metals (and metalloids) such as arsenic, lead, chromium or mercury, are *Corresponding author. Email: pmarinho@ua.pt International Journal of Environmental Health Research Vol. 20, No. 2, April 2010, 87–113 ISSN 0960-3123 print/ISSN 1369-1619 online   2010 Taylor & FrancisDOI: 10.1080/09603120903394649http://www.informaworld.com  D o w nl o ad ed  B y : [ B - o n  C o n s o r ti u m  - 2007]  A t : 10 :09 11  M a r ch 2010  some of the most toxic and can even lead to death if ingested in large doses (acuteexposure), or over large periods of time (chronic exposure). Exposure to HMs fromcontaminated soils may have different pathways, either indirect through theingestion of vegetables grown on contaminated soils or direct as geophagy, butalso by inhalation or dermal contact. Geophagy, the purposeful or inadvertentingestion of soil (Hooda et al. 2004; Intawongse and Dean 2006), is much morecommon than many people suspect and stands for an important pathway of exposure to animals and humans, mainly for children. Children are particularlyvulnerable to HM exposure, especially to lead, as even in low levels, lead causeslong-term neurotoxic effects that may be irreversible (Wong and Li 2004).However, adults exposed to lead rarely show neurological disorders. The riskincreases considerably for the foetus as exposure during pregnancy causesintrauterine delays in foetal development (risk of newborn morbidity andmortality). Sensitivity of the brain towards the toxic effects of lead is considerablygreater in the foetus than in the infant or young child (Reis et al. 2007a). Pathwaysof environmental HM exposure include dust inhalation and dust adhering to plantsand hands that is transferred to the mouth and ingested (Ljung et al. 2006);representing exposure to immobile or weakly mobile metals that otherwise wouldnot pose any kind of risk to humans or animals. This important fact was takeninto account in the selection of the soil size fractions analysed for this study thatfits in a broad, multidisciplinary project, in the field of public health. The projectintends to assess foetal exposure to lead as determined by human andenvironmental biomarkers. Selected environmental biomarkers were bryophytes(moss) whilst the human biomarker selected was the blood from pregnant women.For their biological and ecological properties, bryophytes show several advantagesas monitors of atmospheric deposition (Tyler 1990; Figueira et al. 2002), such asthe lack of protective cuticle and thickened cell walls, numerous cell wallconstituents with negatively charged groups, mineral nutrition obtained mainlyfrom wet and dry deposition, widespread distribution of several species andsimplicity and cheapness of moss biomonitoring methods. In this project, soilgeochemistry covers one of the probable pathways of exposure to environmentallead. As to be expected, the soil sampling grid was geographically conditioned bythe existence of women of a child-bearing age potentially exposed to environmentallead, and the existence of bryophytes. All sampling took place in the central regionof Portugal, in which is concentrated some of the most important industrial areasof the country and less hospitals (a smaller number of large hospitals means thatmore pregnant women will attend the same hospital to give birth, allowing theprocess of blood sampling to become more easy). At this initial stage, the purposesof this study were: (i) to identify relationships amongst five HMs in three differentsampling media and with some site-specific characteristics like land-use, geology,soil grain size, and others; such relationships were identified using MultipleCorrespondence Analysis (MCA), a factorial method of data analysis (Davis 1986;Jambu 1989; Greenacre and Blasius 2006) for the most part applied to searchrelationships between categorical variables (Jime ´nez-Espinosa et al. 1992; Reiset al. 2004, 2007b). (ii) To define spatial patterns of variation for the associationsidentified by MCA; and (iii) to assess atmospheric deposition as a source of HMsin the topsoil by crossing results with the biomonitors. With such methodology weaim to recognise the soil geochemistry of the area and the identification of naturalor anthropogenic sources that control such geochemistry.88  A.P. Reis  et al.  D o w nl o ad ed  B y : [ B - o n  C o n s o r ti u m  - 2007]  A t : 10 :09 11  M a r ch 2010  Figure 1. Location of the study area in Continental Portugal (adapted from AgeˆnciaPortuguesa do Ambiente, 2007, available online at http://www.iambiente.pt/atlas/est/index.jsp). Location of the soil and moss sampling sites; the labels above the dots representthe sample labels. Study area Geographical settings The study area involved all the central region (CR) of Portugal and included thedistricts of Aveiro, Coimbra, Leiria, Viseu, Guarda and Castelo Branco (Figure 1).The region comprises some of the most important industrial areas of the country,namely the Aveiro and Leiria districts. In the countryside, agriculture is one of themain activities, mostly consisting of vineyards, orchards and extensive fields of olivetrees (mainly in the northeastern, eastern and southeastern parts of the study area).This inland area also has the major areas of forest land of the central region andincludes some the Portuguese forest parks.The major urban centres are located in the coastal areas that also have the highestpopulation density of the central region. Aveiro is the district with the most women of child-bearing age (about 48% of the resident women). Castelo Branco is the districtwithlesswomenofchild-bearingage(about38%oftheresidentwomen),accordingtodata from Statistics Portugal (Instituto Nacional de Estatı ´stica [INE] 2007).The altitude of the region varies between sea level and 1993 m a.s.l. in theGuarda district. The geomorphology of the coastal areas is largely controlled by thealluvial plains of several Portuguese rivers and contrasts with the irregular relief of the interior, conditioned by a series of mountains. Environmental settings The geology of Portugal can be divided into two large groups: the Hesperian Massif and the Epi-Hercynian Covering. In the central region, the Epi-Hercynian Covering International Journal of Environmental Health Research  89  D o w nl o ad ed  B y : [ B - o n  C o n s o r ti u m  - 2007]  A t : 10 :09 11  M a r ch 2010  is represented by the western Meso-Cenozoic border, which is displayed in Figure 2as ‘‘clastic sedimentary rocks’’. From the four geotectonic units that form theHesperian Massif, the study area was located at the Central Iberian Zone (Ribeiroet al. 1979) that is mainly constituted by the ante-Ordovician ‘‘SGC’’, a thicksequence of the flysch type (included in the general designation of metassedimentaryrocks in Figure 2), and Hercynian granitoids, in which several types of granites canbe distinguished. Important metallic mineral deposits occur associated with thecontact between the granitoids and the metassediments. One of these is the ‘‘Fila ˜oMetalı ´fero das Beiras’’, a complex system of Cu-Pb bearing sulphides-quartz veinsthat were exploited in several mines. The locations of these mines are shown inFigure 2. Other important occurrences are the tin-tungsten deposits such as those of the Gois-Argemela metallogenic belt. The intrusion of the Hercynian granites has ledto the deposition of wolframite-cassiterite-arsenopyrite bearing quartz veins (Condeet al. 1971; Foxforth et al. 1991; Martins and Borralho 1998). Several W-Sn-Auprimary deposits occur in the metamorphic aureole formed at the contact betweenthe two geological units, which represent the major tin-tungsten resources of thecountry. In the northeast part of the study area, another tin-tungsten metallogenicbelt has srcinated several small mines, presently inactive. Besides the base metalsand tin-tungsten deposits, the study area also contains several uranium deposits(Figure 2). Figure 2. Simplified geology of the study area (adapted from Ageˆncia Portuguesa doAmbiente, 2007, available online at http://www.iambiente.pt/atlas/est/index.jsp). The locationof several closed mines overlay the geology; such mines are indicated by the main ore exploitedat site. U, uranium; W, tungsten; Au, gold; Sn, tin; Pb, lead; Cu, copper; As, arsenic; PE, coal;QZ, quartz. The number above the label reports to the name of the mine, specified in thelegend displayed below the map. 90  A.P. Reis  et al.  D o w nl o ad ed  B y : [ B - o n  C o n s o r ti u m  - 2007]  A t : 10 :09 11  M a r ch 2010
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