Content of Trace Elements in Soils of Eastern Antarctica: Variability Across Landscapes

Sporadic Pb accumulation by plants: Influence of soil biogeochemistry, microbial community and physiological mechanisms

Recent results revealed that considerable Pb accumulation in plants is possible under specific soil conditions that make Pb phytoavailable. In this review, the sources and transformations of Pb in soils, the interaction of Pb with bacteria and specifically the microbiota in the soil, factors and mechanisms of Pb uptake, translocation and accumulation in plants and Pb toxicity in living organisms are comprehensively elaborated. Specific adsorption and post-adsorption transformations of Pb in soil are the main mechanisms affecting the mobility, bioavailability, and toxicity of Pb. The adsorption ability of Pb largely depends on the composition and properties of soils and environmental conditions. Microbial impact on Pb mobility in soil and bioavailability as well as bacterial resistance to Pb are considered. Specific mechanisms conferring Pb-resistance, including Pb-efflux, siderophores, and EPS, have been identified. Pathways of Pb entry into plants as well as mechanisms of in planta Pb transport are poorly understood. Available evidence suggests the involvement of Ca transporters, organic acids and the phytochelatin pathway in Pb transport, mobility and detoxification, respectively.

Influence of marine vertebrates on organic matter, phosphorus and other chemical element levels in Antarctic soils

The presence of marine vertebrates in dense reproductive colonies and other aggregations contributes to the input of organic matter and nutrients into the local environment and it is believed that chemical elements are subsequently remobilized from the excreta of these animals. In this study, we investigated the influence of marine vertebrates on trace elements levels (As, Cd, Co, Cu, Fe, Li, Lu, Mg, Mn, Ni, Pb, Sb, Sc, Se, Sm, Sn, Sr, Tb, U and Zn), nutrient (total phosphorus) and soil organic matter (SOM) content from five locations with and without the presence of seabirds and marine mammals in Admiralty Bay, King George Island, South Shetland Islands, Antarctica. Soils were acid digested using a microwave digestion system, elements were quantified using inductively coupled plasma mass spectrometry and SOM was calculated by loss-on-ignition. The non-influenced and vertebrate-influenced soils had similar concentrations of most of the trace elements assessed, however, we observed a significant increase in SOM and P that was positively correlated with the concentrations of As, Cd, Se, Sr and Zn. Although marine vertebrates did not appear to significantly increase the elemental concentrations in the soils examined here, there is a clear evidence of selective enrichment indicating a zoogenic influence. Comparing our results with other studies, we conclude that soil elemental levels are result from an interplay between local geology, vertebrate diet and colony size. Further studies with increased sample size are required to obtain a better understanding of the influence of marine vertebrates on chemical element levels in Antarctic soils.