Heavy Metal Behavior in Lichen-Mine Waste Interactions at an Abandoned Mine Site in Southwest Japan

The impact of global climate changes on trace and rare earth elements mobilization in emerging periglacial terrains: Insights from western shore of Admiralty Bay (King George Island, Antarctic)

In the rapidly changing climate, the biogeochemical behaviours of trace elements and Rare Earth Elements (REEs) in emerging periglacial environments assumes profound importance. This study provides pivotal insights into this dynamic by investigating the Antarctic's response to global climate change. The bedrock of King George Island is rich in REEs, with the presence of trace metals (TEs), with the highest concentrations of metals found in ornithogenic soil (∑REE 84.01-85.53 mg∙kg-1 dry weight). REEs in the studied soil, found mainly in igneous rocks, as is indicated by the positive correlation of these elements with sodium and calcium. The TEs released as a result of weathering are leached by water flowing down local watercourses to Admiralty Bay, as indicated by the decreasing results of ∑REE = 11.59 μg∙dm-3 in watercourse water, ∑REE = 1.62 μg∙dm-3 in watercourse pools and ∑REE = 0.66 μg∙dm-3 in the water of Admiralty Bay at the outlet of the watercourse. Water originating from the melting of snow on the glacier also carried REEs (∑REE = 0.14 μg∙dm-3), a fact which suggest the further influx of these elements from atmospheric deposition. The Prasiola crispa turned out to be the most susceptible to the accumulation of REEs (∑ 80.73 ± 5.05 μg g-1) and TEs, with the exception of chromium and zinc, whose concentrations were found to be at their highest in Deschampsia antarctica. In Usnea antarctica, Xanthoria candelaria, and Ceratodon purpureus and Politrichastrum alpinum, a dominant role in the accumulation of REEs was played by HREEs. The determined enrichment factor (EF) indicates that the soil cover is a source of REEs (EFAlgae for ∑REE = 5.07; EFLichen for ∑REE = 6.65; EFBryophyta for ∑REE = 5.04; EFVascular for ∑REE = 4.38), while Ni, As and Pb accumulated in plants may originate from other sources than the soil.

Risk Assessment of Contamination by Potentially Toxic Metals: A Case Study in the Vicinity of an Abandoned Pyrite Mine

Abandoned mining areas can display soil and water pollution and also a high incidence of endemic diseases. Here, based on preliminary results on mental retardation and high incidence rates of cancers, we investigate the contamination status and potential ecological risk at an abandoned pyrite mine located in Xianju village, Hubei province, central China. The study focused on the three potentially toxic metals As, Pb, and Zn and four other common elements, including Ca, Fe, S, and Se. Soil samples were collected from 12 sites and leachate seeping from five sites. Leachates were strongly acidic compared to the soil, with pH values <3.22. Soil As and Se concentrations exceeded the Chinese Grade II standards for soil environmental quality (GB 15618-2009) (30 and 3 mg·kg−1, respectively), ranging from 33.6 ± 0.7 to 78.2 ± 1.0 mg As·kg−1 dry matter (DM) and 5.3 ± 0.8 to 17.1 ± 1.4 mg Se·kg−1 DM. Arsenic, Fe, Se, and S in leachates all exceeded the Chinese Grade III standard for surface water environmental quality (GB 3838-2002) (0.1, 0.3, 0.03, and 1.0 mg·L−1). The potential ecological risks from Pb and Zn in soils were low, but As in soils and leachates represented a moderate or strong risk to children according to the Nemerow index and hazard quotient. Soil replacement combined with further remediation measures is required to remediate the contaminated area.

Tolerance mechanism of Triarrhena sacchariflora (Maxim.) Nakai. seedlings to lead and cadmium: Translocation, subcellular distribution, chemical forms and variations in leaf ultrastructure

Hydroponic experiments were conducted to assess the accumulation, translocation, and chemical forms of lead (Pb) and cadmium (Cd) in the roots, stems, and leaves of Triarrhena sacchariflora seedlings and the associated variation in leaf ultrastructure. The leaves and leaf ultrastructure showed no significant symptoms of toxicity with 0.05 mM Pb or 0.01 mM Cd exposure for 10d. Chlorosis and wilting were observed in leaves when the Pb and Cd concentration was higher than 0.1 and 0.05 mM in the medium, respectively, as demonstrated by severe ultrastructural modifications at higher concentration in the leaves, such as plasmolysis, cell wall detachment, chloroplast swelling, nuclear condensation, and even nuclear fragmentation. The Pb and Cd concentrations in the roots was significantly higher than those in the stems and leaves. This indicated low Pb and Cd translocation from the roots to the aboveground parts. Subcellular distribution analysis showed that the majority of Pb and Cd was bound to the cell wall, especially in the roots, indicating that the cell wall likely constitutes a crucial storage site for Pb and Cd. This mechanism decreases the translocation of Pb and Cd across membranes and is more effective than vacuolar compartmentation. The majority of Pb and Cd exited in form of insoluble Pb/Cd-pectate or -oxalate complexes in the plant. In conclusion, higher concentrations of Pb or Cd induced premature senescence. High Pb and Cd enrichment was observed in the roots, which decreased the translocation of Pb and Cd from the roots to the aboveground tissues. The immobilization of Pb or Cd by the cell wall is important for plant detoxification and can protect protoplasts from Pb or Cd toxicity. Pb and Cd mainly existed in insoluble Pb/Cd-phosphate or -oxalate complexes, exhibiting low activity and thereby limiting symplastic transport and suppressing toxicity.