PubMed · 14935351
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1952-07-19. LEAD poisoning.. https://pubmed.ncbi.nlm.nih.gov/14935351/
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In this study, the potential genotoxic effects and phytoremediation capacity of Ludwigia repens J.R. Forst. were evaluated under lead (Pb) stress in contaminated aquatic environments. To achieve this, clonal L. repens plants were used to investigate their ability to remove Pb from freshwater systems and the experimental setup was established in controlled aquarium conditions. The plants were exposed to 0, 10, 25, 50 and 100 micromolar (μM) concentrations of Pb(NO3)2 in a 0.2% Hoagland nutrient solution for a period of ten days. Experimental results showed that Pb accumulated in both stems and leaves of L. repens. Although Pb levels did not meet hyperaccumulator criteria, the bioaccumulation index (BAI), bioconcentration factor (BCF) and translocation factor (TF) values revealed that the plant was capable of accumulating noteworthy amounts of Pb. In parallel, band profile analysis revealed new band appearances only with the UBC 812 primer, while no band loss or new band formation was detected with the other primers (UBC 808, UBC 826, UBC 833 and UBC 834). Instead, only changes in band intensities were observed, indicating a low polymorphism rate and a high level of genomic template stability (GTS). The findings also indicate that L. repens exhibits notable tolerance to Pb stress, as supported by high BAI, BCF and TF values in the absence of visible phytotoxic symptoms. Additionally, the consistent and progressive decline in mineral nutrient levels across Pb treatments, together with the moderate decline in total chlorophyll content, further supports the existence of a coordinated physiological adjustment, potentially reflecting a tolerance mechanism aimed at maintaining ionic balance under heavy metal stress. Moreover, low polymorphism rates and high genomic template stability (GTS) values derived from molecular analyses suggest that this species may serve as a genetically stable and physiologically resilient aquatic plant. These combined traits highlight its potential to contribute effectively to phytoremediation applications, particularly when co-cultivated with established Pb hyperaccumulator species.
Non-lead aprons using composite materials are often used for radiation protective aprons instead of heavy lead aprons. However, the protective effect of the lighter, non-lead aprons has not been well evaluated, and it is not yet clear how they compare with lead aprons. Therefore, we investigated the protective performance of non-lead aprons theoretically and experimentally by comparing them with lead aprons under clinical conditions. We measured the energy spectra for direct and scattered X-rays passing through protective aprons or not, and measured doses with glass dosimeters for validation of theoretical calculations based on the energy spectra. We found that the protective effect of non-lead aprons was higher than that of lead aprons at X-ray of tube voltages of 70-100 kV, which are often used for radiography and fluorography. This demonstrated that the non-lead aprons are more useful in many situations than heavy lead aprons.
A sand culture experiment was conducted to investigate whether mycorrhizal colonization and mycorrhizal fungal vesicular numbers were influenced by metal lead, and whether mycorrhizae enhance host plants tolerance to metal lead. Metal lead was applied as Pb(NO3)2 in solution at three levels (0, 300 and 600 mg kg(-1) sand). Five mycorrhizal host plant species, Kummerowia striata (Thunb.) Schindl, Ixeris denticulate L., Lolium perenne L., Trifolium repens L. and Echinochloa crusgalli var. mitis were used to examine Pb-mycorrhizal interactions. The arbuscular mycorrhizal inoculum consisted of mixed spores of mycorrhizal fungal species directly isolated from orchard soil. Compared to the untreated control, both Pb concentrations reduced mycorrhizal colonization by 3.8-70.4%. Numbers of AM fungal vesicles increased by 13.2-51.5% in 300 mg Pb kg(-1) sand but decreased by 9.4-50.9% in 600 mg Pb kg(-1) sand. Mycorrhizae significantly enhanced Pb accumulation both in shoot by 10.2-85.5% and in root by 9.3-118.4%. Mycorrhizae also enhanced shoot biomass and shoot P concentration under both Pb concentrations. Root/shoot ratios of Pb concentration were higher in highly mycorrhizal plant species (K.striata, I. denticulate, and E. crusgalli var. mitis) than that in poorly mycorrhizal ones (L. perenne and T. repens,). Mycorrhizal inoculation increased the root/shoot ratio of Pb concentration of highly mycorrhizal plant species by 7.6-57.2% but did not affect the poorly mycorrhizal ones. In the treatments with 300 Pb mg kg(-1) sand, plant species with higher vesicular numbers tended to show higher root/shoot ratios of the Pb concentration. We suggest that under an elevated Pb condition, mycorrhizae could promote plant growth by increasing P uptake and mitigate Pb toxicity by sequestrating more Pb in roots.