Globally,copper(Cu)accumulation in soils is a major environmental concern.Agricultural organic waste and some bacterial species can readily absorb metals in an eco-friendly manner,and thus are commonly used in metal-c...Globally,copper(Cu)accumulation in soils is a major environmental concern.Agricultural organic waste and some bacterial species can readily absorb metals in an eco-friendly manner,and thus are commonly used in metal-contaminated soil remediation.This study investigates the change in Cu fractions during the aging process and the time effects of rice straw(RS)and engineered bacteria(EB)(Pseudomonas putida X4/pIME)on reduction of Cu mobility.Three typical Chinese soils(red,cinnamon,and black soils)were incubated with RS or RS+EB in the presence of exogenous Cu for 24 months.The soil physicochemical properties,reactive soil components,Cu fractions,and Cu mobility were determined over time.The Cu mobility factor(MF)values were the lowest in the black soil(6.4-9.2)because of its high organic carbon and clay contents.The additions of both RS and RS+EB accelerated Cu stabilization during the aging process in all three soils.The Cu MF values decreased with time during the initial 20 months;however,the MF values increased thereafter in all soils,which might be due to the reduction of humic substances and amorphous iron oxides and the increase in iron oxides complexed on the organic matter.The reduction rates of Cu MF were similar after 16,24,and more than 24 months in the red,cinnamon,and black soils,respectively,indicating that RS and RS+EB could limit Cu mobility at different times in various soils.The RS treatment showed the greatest efficiency in reducing Cu mobility in the red,cinnamon,and black soils after 12,12,and 8 months of incubation,respectively.The RS+EB treatment was more efficient than the RS treatment in the red soil during the initial 8 months of the incubation period.Our study provides theoretical support for Cu risk assessments and RS supplementation for Cu remediation in different soils.展开更多
For a finite group G,the co-maximal subgroup graphΓ(G)of G is a graph whose vertices are proper subgroups of G,and two distinct vertices H and K are adjacent if and only if H K=G.The deleted co-maximal subgroup graph...For a finite group G,the co-maximal subgroup graphΓ(G)of G is a graph whose vertices are proper subgroups of G,and two distinct vertices H and K are adjacent if and only if H K=G.The deleted co-maximal subgroup graphΓ^(∗)(G)is obtained by removing isolated vertices fromΓ(G).Firstly,we provide necessary and sufficient conditions forΓ^(∗)(G)to be connected;in particular,from the viewpoint of normal subgroups in G,we give some sufficient conditions forΓ^(∗)(G)to be connected.Secondly,for a finite abelian group G we prove that the diameter ofΓ^(∗)(G),diam(Γ^(∗)(G)),is at most 3.Also,we characterize G with diam(Γ^(∗)(G))=i for i=1,2,3 and we give characterizations for G withΓ^(∗)(G)being complete bipartite graphs and null graphs separately.Finally,we show that for the semidirect product G of two finite cyclic groups,Γ^(∗)(G)is connected and diam(Γ^(∗)(G))=2.展开更多
基金supported by the National Key R&D Program of China(No.2019YFC1605600)the National Natural Science Foundation of China(No.32072662)+5 种基金the National Youth Natural Science Foundation(No.4180071811)the Natural Science Foundation of Guangdong Province,China(No.2020A1515010819)the Doctor-Initiated Project of the Public Monitoring Center for Agro-Product of Guangdong Academy of Agricultural Sciences,China(No.ZXRC201903)the President Foundation of Guangdong Academy of Agricultural Sciences,China(No.202017)the Special Found for Scientific Innovation Strategy-Construction of High Level Academy of Agriculture Science,China(No.R2021YJ-QG006)the Foundation Project of Director of Institute of Quality Standard and Monitoring Technology for Agro-Products of Guangdong Academy of Agricultural Sciences,China(No.DWJJ-202113)。
文摘Globally,copper(Cu)accumulation in soils is a major environmental concern.Agricultural organic waste and some bacterial species can readily absorb metals in an eco-friendly manner,and thus are commonly used in metal-contaminated soil remediation.This study investigates the change in Cu fractions during the aging process and the time effects of rice straw(RS)and engineered bacteria(EB)(Pseudomonas putida X4/pIME)on reduction of Cu mobility.Three typical Chinese soils(red,cinnamon,and black soils)were incubated with RS or RS+EB in the presence of exogenous Cu for 24 months.The soil physicochemical properties,reactive soil components,Cu fractions,and Cu mobility were determined over time.The Cu mobility factor(MF)values were the lowest in the black soil(6.4-9.2)because of its high organic carbon and clay contents.The additions of both RS and RS+EB accelerated Cu stabilization during the aging process in all three soils.The Cu MF values decreased with time during the initial 20 months;however,the MF values increased thereafter in all soils,which might be due to the reduction of humic substances and amorphous iron oxides and the increase in iron oxides complexed on the organic matter.The reduction rates of Cu MF were similar after 16,24,and more than 24 months in the red,cinnamon,and black soils,respectively,indicating that RS and RS+EB could limit Cu mobility at different times in various soils.The RS treatment showed the greatest efficiency in reducing Cu mobility in the red,cinnamon,and black soils after 12,12,and 8 months of incubation,respectively.The RS+EB treatment was more efficient than the RS treatment in the red soil during the initial 8 months of the incubation period.Our study provides theoretical support for Cu risk assessments and RS supplementation for Cu remediation in different soils.
基金supported by National Natural Science Foundation of China(Grant Nos.12071194,12361072)2023 Xinjiang Uygur Autonomous Region Natural Science Foundation General Project(No.2023D01A36)2023 Xinjiang Uygur Autonomous Region Natural Science Foundation for Youths(No.2023D01B48).
文摘For a finite group G,the co-maximal subgroup graphΓ(G)of G is a graph whose vertices are proper subgroups of G,and two distinct vertices H and K are adjacent if and only if H K=G.The deleted co-maximal subgroup graphΓ^(∗)(G)is obtained by removing isolated vertices fromΓ(G).Firstly,we provide necessary and sufficient conditions forΓ^(∗)(G)to be connected;in particular,from the viewpoint of normal subgroups in G,we give some sufficient conditions forΓ^(∗)(G)to be connected.Secondly,for a finite abelian group G we prove that the diameter ofΓ^(∗)(G),diam(Γ^(∗)(G)),is at most 3.Also,we characterize G with diam(Γ^(∗)(G))=i for i=1,2,3 and we give characterizations for G withΓ^(∗)(G)being complete bipartite graphs and null graphs separately.Finally,we show that for the semidirect product G of two finite cyclic groups,Γ^(∗)(G)is connected and diam(Γ^(∗)(G))=2.
