Lead(Pb)and zinc(Zn)are widely recognized as common environmental contaminants,contributing to soil degradation and posing risks to environmental health.Combining functional carbon-based materials with microorganisms has been considered as an effective and environmentally friendly strategy for remediating Pb/Zn-contaminated soil.However,there is still a lack of understanding the connection between heavy metal immobilization and plant responses,which hampers practical applications.Here,a 90-day pot experiment was conducted to investigate the integrated effects of biochar(WS700)and microorganisms including inorganic phosphate-solubilizing bacteria(IPSB)and sulfate reducing bacteria(SRB)on Pb and Zn synchronous immobilization and the physiological responses of Brassica rapa var.chinensis(Brassica).Compared with CK,bacteria-loaded biochar treatment declined the exchangeable Pb and Zn fraction by 94.69%−98.37%and 94.55%−99.52%,while increasing the residual state Pb and Zn by 75.50%−208.58%and 96.71%−110.85%,respectively.Three amendments enhanced Brassica growth by improving total chlorophyll content and superoxide dismutase(SOD)and peroxidase(POD)activities.The bacteria-loaded biochar treatment effectively regulated stomatal conductance and reduced intercellular CO_(2) concentration.Moreover,compared with CK,three amendments reduced MDA content by 28.84%,28.30%and 41.60%,respectively,under the high concentration of Pb and Zn.The findings demonstrated the significant role of bacterial-biochar consortia in immobilizing Pb and Zn and mitigating Pb and Zn-induced stress in plants by regulating photosynthetic characteristics and antioxidant enzyme activities.
LI XueZHU Xiao-liZHU FengLI XingZHANG Zi-yeXUE Sheng-guo
Unraveling the precise mineralization age is vital to understand the geodynamic setting and ore-forming mechanism of the sediment-hosted Pb-Zn deposit;this has long been a challenge.The Sichuan-Yunnan-Guizhou(SYG)triangle in the southwestern margin of the Yangtze Block is a globally recognized carbonate-hosted Pb-Zn metallogenic province and also an essential part of the South China low-temperature metallogenic domain.This region has>30 million tons(Mt)Zn and Pb resources and shows the enrichment of dispersed metals,such as Ga,Ge,Cd,Se,and Tl.During the past 2 decades,abundant data on mineralization ages of Pb-Zn deposits within the SYG triangle have been documented based on various radioisotopic dating methods,resulting in significant progress in understanding the geodynamic background and ore formation of Pb-Zn deposits hosted in sedimentary rocks at SYG triangle.This paper provides a comprehensive summary of the geochronological results and Pb-Sr isotopic data regarding Pb-Zn deposits in the SYG triangle,which identified two distinct Pb-Zn mineralization periods influencing the dynamic processes associated with the expansion and closure of the Paleo-Tethys Ocean in the western margin of the Yangtze Block.The predominant phase of Pb-Zn mineralization at SYG triangle spanned from the Middle Triassic to Early Jurassic(226-191 Ma),which was intensely correlated with the large-scale basin fluid transport triggered by the closure of the Paleo-Tethys Ocean and Indosinian orogeny.The secondary Pb-Zn mineralization phase occurred during the Late Devonian to Late Carboniferous and was controlled by extensional structures associated with the expansion of the Paleo-Tethys Ocean.Further investigation is necessary to clarify the occurrence and potential factors involved in the Pb-Zn mineralization events during the Late Devonian to Late Carboniferous.
