Heavy metal contents, mobility and origin in agricultural topsoils of the Galápagos Islands

• Published in: Chemosphere (Oxford) 2021-06, Vol.272, p.129821-129821, Article 129821
• Main Authors: Dinter, Tamara C., Gerzabek, Martin H., Puschenreiter, Markus, Strobel, Bjarne W., Couenberg, Paulina M., Zehetner, Franz
• Format: Article
• Language: English
• Subjects: Agricultural soils; Aqua regia; Cadmium; China; Ecuador; Environmental Monitoring; Galápagos Islands; Heavy metals; Lead; Metals, Heavy - analysis; Risk Assessment; Soil - chemistry; Soil Pollutants - analysis; Trace elements; Volcanic ash soils
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2021.129821

While the Galápagos Islands have been renowned for their unique flora and fauna since the time of Charles Darwin, the soils of the isolated island chain have been mostly overlooked and little information on their heavy metal contents is available. The aim of this study was therefore to examine the total heavy metal (Cd, Co, Cr, Cu, Ni, Pb, U, Zn) contents of soils from the agricultural areas on islands Isabela, Santa Cruz and San Cristóbal, and identify trends with duration of exposure to weathering processes. Additionally, the mobility of these elements was assessed using ammonium nitrate extraction. In general, levels of Cd, Co, Cr, Cu, Ni and Zn were high compared to other world locations, while Pb levels were low and U levels were similar. Ni, Co, Cr, and to a lesser extent Pb and U tended to accumulate with increasing weathering duration. Soil concentrations of Cd, Zn, Cu, and possibly Pb and U, may have been influenced by use of agrochemicals, particularly on Santa Cruz Island. Mobility of Cd displayed an increasing trend with soil age, while Ni mobility decreased. Many soils had total contents of Cd, Co, Cr, Cu, Ni and Zn above threshold values indicating possible ecological or health risks. Systematic examination of trace element contents in soils from pristine national park areas would further assist in the delineation of background levels and the development of soil quality standards to ensure crop quality, animal and human health on this unique island chain. •Total contents of Cd, Co, Cr, Cu, Ni & Zn were above threshold values in many soils.•Ni, Co and Cr tended to accumulate in the more weathered soils.•Cd mobility was highest in older soils, while Ni mobility was lowest.