Though gold mines provide signi cant economic bene ts to local governments, mining causes soil pollution by potentially toxic trace elements (PTEs) in mining areas, especially in the Qinghai-Tibet Plateau. Screening of native plant species from mining areas is now an effective, inexpensive, and ecofriendly method for the remediation of PTEs in situ. In the present study, we conducted experiments to assess the accumulation of As, Cd, Pb, and Zn in 12 native plant species growing on a typical gold mining area in Qinghai-Tibet Plateau. Our results showed that rhizosphere soils have high soil organic matter content, high levels of As, and moderate levels of Cd. G. pylzowianum accumulated relatively higher As in its shoots and exhibited TF higher than 1 for As (4.65), Cd (1.87), and Pb (1.36). P. saundersiana had BCF-S higher than 1 for Cd (4.52) and Pb (1.70), whereas its TF was higher than 1 for As, Cd, Pb, and Zn. These plant species also exhibit strong tolerance to these PTEs. Furthermore, E. nutans accumulated low levels of As, Cd, Pb, and Zn in their shoots and exhibited TF values lower than 1 for the four PTEs. Therefore, G. pylzowianum could be used for the in situ phytoextraction of As, and P. saundersiana can be used as an effective plant for Cd and Pb phytoextraction. E. nutans is better suited for the phytostabilisation of multiple PTEs. Our study is of signi cant importance for introducing native plant species to remediate PTE-contaminated soils, particularly As and Cd, and has a good potential for developing PTE phytoremediation strategies at mining sites. HighlightsAs was the prime pollutant in soils surrounding the gold mine.Phytoremediation of PTEs in 12 native plants was examined at a gold mining site. P. saundersiana had TF higher than 1 for all PTEs.
Though gold mines provide significant economic benefits to local governments, mining causes soil pollution by potentially toxic trace elements (PTEs) in mining areas, especially in the Qinghai-Tibet Plateau. Screening of native plant species from mining areas is now an effective, inexpensive, and eco-friendly method for the remediation of PTEs in situ. In the present study, we conducted experiments to assess the accumulation of As, Cd, Pb, and Zn in 12 native plant species growing on a typical gold mining area in Qinghai-Tibet Plateau. Our results showed that rhizosphere soils have high soil organic matter content, high levels of As, and moderate levels of Cd. G. pylzowianum accumulated relatively higher As in its shoots and exhibited TF higher than 1 for As (4.65), Cd (1.87), and Pb (1.36). P. saundersiana had BCF-S higher than 1 for Cd (4.52) and Pb (1.70), whereas its TF was higher than 1 for As, Cd, Pb, and Zn. These plant species also exhibit strong tolerance to these PTEs. Furthermore, E. nutans accumulated low levels of As, Cd, Pb, and Zn in their shoots and exhibited TF values lower than 1 for the four PTEs. Therefore, G. pylzowianum could be used for the in situ phytoextraction of As, and P. saundersiana can be used as an effective plant for Cd and Pb phytoextraction. E. nutans is better suited for the phytostabilisation of multiple PTEs. Our study is of significant importance for introducing native plant species to remediate PTE-contaminated soils, particularly As and Cd, and has a good potential for developing PTE phytoremediation strategies at mining sites.
To study the vortex-induced force (VIF) model of a steel box girder with projecting slab, a cable-stayed bridge with a main span of 160[Formula: see text]m was taken as the research object in this study. First, a computational fluid dynamics (CFD) numerical simulation method was used to calculate the amplitude characteristics of vortex-induced vibration (VIV) of the steel box girder with projecting slab, and the calculated results were compared with those of wind tunnel tests. Then, the time–history of VIF of the bridge girder was extracted based on the validated numerical simulation results, and a new mathematical model of VIF for the steel box girder with projecting slab was established according to the residual values between the reconstructed and target values. On such a basis, the steady VIV amplitude expression of the bridge girder was deduced according to the principle of the work done by the damping terms in the VIF model. Finally, the performance function of the maximum VIV amplitude was established with six random variables. Furthermore, the failure probability of VIV was calculated by the maximum entropy principle combined with the multiplicative dimensional reduction method, and the sensitivity of each random variable was analyzed as well. The results show that the lock-in region, VIV amplitudes and vibration frequency of the bridge girder calculated from the numerical simulations agree well with those from the wind tunnel tests, and the maximum amplitude occurs at the oncoming wind speed of 7.2[Formula: see text]m/s. In addition to the most important fundamental-frequency component, there also exist double- and triple-frequency components in the time–history of VIF of the bridge girder, which implies the VIF exhibits certain nonlinear characteristics. According to the proposed expression of the steady VIV amplitude of the bridge girder, the steady amplitude decreases as the absolute value of parameter [Formula: see text] increases, but it increases with the increase of the parameter [Formula: see text]. The failure probability of VIV of the bridge girder is calculated to be 0.9616 based on the performance function with six random variables. Besides, it is found that the damping ratio [Formula: see text] has great effects on the reliability of VIV, while the vertical bending frequency [Formula: see text] exerts less effects.
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