Trace metal concentrations in soil-plant complex in rocky shore salt marshes of Central Patagonia

Abstract

Population growth and industrialization involve environmental problems, such as metal pollution, and coastal environments are particularly susceptible to such issues. Within this framework, we aimed: (i) to determine the levels of trace metals in soils and Spartina densiflora tissues in rocky shore marshes of Central Patagonia; (ii) to relate metal concentration patterns in the different soil-plant complex fractions to environmental conditions; and (iii) to investigate whether geographical metal concentration patterns can be explained with anthropogenic influences and sources and/or by local prevailing biogeochemical processes. For this purpose, soil samples and associated vegetation were collected in five rocky shore marshes located at different distances from an urban or industrial area. The concentration of Al, Cd, Cr, Cu, Fe, Ni, Pb, and Zn in soils (pseudototal and bioavailable) and in plants (roots and shoots) was determined. Then the enrichment factor, bioaccumulation and translocation factor were calculated. The soil mineralogy and the behavior of these metals according to different soil variables were discussed. The results showed different behavior and level of anthropic impact according to the metal considered. Salt marshes located on the southern edge of the Nuevo Gulf showed the highest concentrations of metals. Fe, Al, Cu and Zn showed mostly a natural origin. Fe and Al were mainly in soils rather than in plants, while Cu and Zn were similarly distributed in both matrixes. Although Cd in soils showed enrichment, it would have a natural origin. Also, it was scarce in the soil and was mostly concentrated in Spartina’ roots. Pb, Cr and Ni showed anthropic enrichment too, being mainly derived from the port and industrial activities. Pb had significant representation in all soil-plant subsystems and showed the highest bioavailability in soils. Cr and Ni, were found in high concentration in the soil and showed a high bioaccumulation in roots. The human impact level in rocky shore marshes of the Nuevo Gulf in Central Patagonia associated to the trace metals pollution varies from being scarce to significantly important, with the marshes located in its southern margin showing the worst scenarios.