RESUMO
A geochemical-environmental mapping was carried for a low polluted forest in North-western Mexico (Santiago Papasquiaro mining area), as part of the North American forests accounting for environmental behavior of arsenic (As), lead (Pb), zinc (Zn) and copper (Cu) in soil and tree components (stem wood and aciculums). Spectroscopic and microscopic techniques along with standard protocols were used to determine the mineralogical phases containing these elements, and their corresponding spatial distributions in soil and forests and mobility. In soil, total As, Pb, Zn and Cu ranged from 4.9 to 98.3, 19.6 to 768.6, 19.6 to 407.1, and 1.6 to 63.8â¯mgâ¯kg-1, respectively. Ultrafine particles (<5-10⯵m) of arsenopyrite and sphalerite (and complex Zn-Fe phase) were the main As and Zn-bearing phases determined by SEM-EDS, respectively. Complex Pb-Cu-Fe and Cu-O oxide-like phases were the only ones containing Pb and Cu, respectively. Mobility was low for Pb, Zn and Cu, whereas a significant mobility was assessed for As. Concentrations vs. depth profiles suggested progressive accumulations of As, Pb, Zn and Cu in top soil. Total As, Pb, Zn and Cu in pine stem wood varied from 11.5 to 184.5, 98.9 to 7359.8, 3242.7 to 22197.3, 689.2 to 7179.6⯵gâ¯kg-1, respectively. The respective concentrations in the pine needles ranged from 50 to 624.2, 100 to 16353.1, 120 to 46440.9 and 720 to 7200⯵gâ¯kg-1, indicating an active bioaccumulation of As, Pb, Zn and Cu. A prospective environmental behavior was discussed for As, Pb, Zn and Cu in the low-polluted forest.
Assuntos
Arsênio/análise , Cobre/análise , Ecossistema , Chumbo/análise , Poluentes do Solo/análise , Solo/química , Zinco/análise , Arsênio/metabolismo , Disponibilidade Biológica , Cobre/metabolismo , Monitoramento Ambiental , Florestas , Chumbo/metabolismo , México , Poluentes do Solo/metabolismo , Zinco/metabolismoRESUMO
Total, bioaccessible and mobile concentrations of arsenic and fluorine are determined in polluted surface soil within the Comarca Lagunera region using standardized protocols to obtain a full description of the environmental behavior for these elements. The composition of mineral phases associated with them is evaluated with microscopic and spectroscopic techniques. Mineralogical characterizations indicate that ultra-fine particles (<1-5 µm) including mimetite-vanadite (Pb5(AsO4)3Cl, Pb5(AsO4, VO4)3Cl)-like, lead arseniate (Pb3(AsO4)2)-like and complex arsenic-bearing compounds are main arsenic-bearing phases, while fluorite (CaF2) is the only fluorine-bearing phase. Total fluorine and arsenic concentrations in surface soil range from 89.75 to 926.63 and 2.7-78.6 mg kg-1, respectively, exceeding in many points a typical baseline value for fluorine (321 mg kg-1), and trigger level criterion for arsenic soil remediation (20 mg kg-1); whereas fluoride and arsenic concentrations in groundwater vary from 0.24 to 1.8 mg L-1 and 0.12-0.650 mg L-1, respectively. The main bioaccessible percentages of soil in the gastric phase (SBRC-G) are estimated for arsenic from 1 to 63%, and this parameter in the intestinal phase (SBRC-I) fluorine from 2 to 46%, suggesting human health risks for this region. While a negligible/low mobility is found in soil for arsenic (0.1-11%), an important mobility is determined for fluorine (2-39%), indicating environmental risk related to potential fluorine release. The environmental and health risks connected to arsenic and fluorine are discussed based on experimental data.