Field study on the accumulation of trace elements by vegetables produced in the vicinity of abandoned pyrite mines

• Published in: The Science of the total environment Vol. 470-471; pp. 1233 - 1242
• Main Authors: Alvarenga, Paula, Simões, Isabel, Palma, Patrícia, Amaral, Olga, Matos, João Xavier
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-02-2014
• Subjects: Bioavailability; Edible plants; Environmental Monitoring; Food Contamination - analysis; Iberian Pyrite Belt; Iron; Mining; Mining activities; Soil contamination; Soil Pollutants - analysis; Sulfides; Trace elements; Trace Elements - analysis; Vegetables - chemistry; Iberian Pyrite Belt; Trace elements; Bioavailability; Edible plants; Mining activities; Soil contamination
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2013.10.087

To evaluate the accumulation of trace elements (TE) by vegetables produced in the vicinity of abandoned pyrite mines, eighteen different small farms were selected near three mines from the Portuguese sector of the Iberian Pyrite Belt (São Domingos, Aljustrel and Lousal). Total and bioavailable As, Cu, Pb, and Zn concentrations were analyzed in the soils, and the same TE were analyzed in three different vegetables, lettuce (Lactuca sativa), coriander (Coriandrum sativum), and cabbage (Brassica oleracea), collected at the same locations. The soils were contaminated with As, Cu, Pb, and Zn, since their total concentrations exceeded the considered soil quality guideline values for plant production in the majority of the sampling sites. The maximum total concentrations for those TE were extremely high in some of the sampling sites (e.g. 1851mgAskg−1 in São Domingos, 1126mgCukg−1 in Aljustrel, 4946mgPbkg−1 in São Domingos, and 1224mgZnkg−1 in Aljustrel). However, the soils were mainly circumneutral, a factor that contributes to their low bioavailable fractions. As a result, generally, the plants contained levels of these elements characteristic of uncontaminated plants, and accumulation factors for all elements <1, typical of excluder plants. Furthermore, the estimated daily intake (EDI) for Cu and Zn, through the consumption of these vegetables, falls below the recommended upper limit for daily intake of these elements. The sampling site that stood out from the others was located at São João de Negrilhos (Aljustrel), where bioavailable Zn levels were higher, a consequence of the slight acidity of the soil. Therefore, the Zn content in vegetables was also higher, characteristic of contaminated plants, emphasizing the risk of Zn entering the human food chain via the consumption of crops produced on those soils.
•Soils in kitchen gardens near pyrite mines are heavily contaminated with As, Cu, Pb, and Zn.•Soil is mainly neutral, due to soil amendment, which contributes to the low bioavailability of TE.•Generally, vegetables contain levels of these elements characteristic of uncontaminated plants.•Risk is considerable where the soil pH is acidic, triggering high Zn bioavailable concentrations.•If the soil pH is not controlled, there is a risk of consuming metal contaminated vegetables.