Flood is one of the most devastating natural hazards.Employing machine learning models to construct flood susceptibility maps has become a pivotal step for decision-makers in disaster prevention and management.Existin...Flood is one of the most devastating natural hazards.Employing machine learning models to construct flood susceptibility maps has become a pivotal step for decision-makers in disaster prevention and management.Existing flood conditioning factors inadequately account for regional characteristics of flood in the depiction of topography,potentially leading to an overestimation of flood susceptibility in flat areas.Addressing this gap,this study proposes a novel flood conditioning factor,local convexity factor(LCF),to enhance the accuracy of flood susceptibility modeling.Initially,LCF is computed based on a standard normal Gaussian surface to highlight elevation variations in local terrain.Subsequently,LCF is applied to flood susceptibility modeling using seven machine learning models across four distinct basins.Comparative analysis is conducted between flood susceptibility maps with and without the application of LCF to evaluate its impact on flood susceptibility modeling.The results demonstrate that the proposed LCF can enhance the accuracy of flood susceptibility modeling to varying degrees,across the four basins investigated.The Fujiang basin exhibited the most substantial improvement,with its AUC improved from 0.861 to 0.886,Producer’s Agreement improved from 0.869 to 0.899,and Overall Agreement improved from 0.778 to 0.811.Comparation with hydrodynamic inundation maps shows that particularly in relatively flat terrain areas,flood susceptibility maps incorporating LCF offer more precise delineation between flood-prone and non-flood-prone zones.This research holds potential for widespread application in the prediction of flood susceptibility using machine learning models,providing a novel perspective for enhancing their accuracy.展开更多
The variation of seedling characteristics under different water supply conditions is strongly associated with drought resistance in rice （Oryza sativa L.） and a better elucidation of its genetics is helpful for impr...The variation of seedling characteristics under different water supply conditions is strongly associated with drought resistance in rice （Oryza sativa L.） and a better elucidation of its genetics is helpful for improving rice drought resistance. Ninety-six doubled-haploid （DH） rice lines of an indica and japonica cross were grown in both flooding and upland conditions and QTLs for morphological traits at seedling stage were examined using 208 restriction fragment length polymorphism （RFLP） and 76 microsatellite （SSR） markers. A total of 32 putative QTLs were associated with the four seedling traits： average of three adventitious root lengths （ARL）, shoot height （SH）, shoot biomass （SW）, and root to shoot dry weight ratio （RSR）. Five QTLs detected were the same under control and upland conditions. The ratio between the mean value of the seedling trait under upland and flooding conditions was used for assessing drought tolerance. A total of six QTLs for drought tolerance were detected. Comparative analysis was performed for the QTLs detected in this case and those reported from two other populations with the same upland rice variety Azucena as parent. Several identical QTLs for seedling elongation across the three populations with the positive alleles from the upland rice Azucena were detected, which suggests that the alleles of Azucena might be involved in water stress-accelerated elongation of rice under different genetic backgrounds. Five cell wall-related candidate genes for OsEXPI, OsEXP2, OsEXP4, EXT, and EGase were mapped on the intervals carrying the QTLs for seedling traits.展开更多
Biodegradation of 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane(DDT)in soil by laccase extract from white rot fungi under different experimental conditions was investigated.DDTs,which stands for the sum of p,p′-DDE,...Biodegradation of 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane(DDT)in soil by laccase extract from white rot fungi under different experimental conditions was investigated.DDTs,which stands for the sum of p,p′-DDE,o,p′-DDT,p,p′-DDD and p,p′-DDT in soil was degraded efficiently,and the residue decreased rapidly during the first 15 days and then slowly during the period of 16-25 days.The biodegradation of DDTs in soil fitted the pseudo-first-order kinetics.For 5,10,15 and 25 days of incubation with laccase,the residue of DDTs in soil under different atmospheres was decreased by 20%-33%,34%-52%,41%-61%and 41%-69%respectively,under different flooding conditions that was decreased by 12%-17%,17%-30%,30%-45%and 35%-52%respectively, and for different soils that was decreased by 25%-34%,39%-53%,44%-58%and 47%-62%respectively.The half-life of DDTs in soil ranged from 15.07 to 32.95 days under O2,air or N2 atmospheres,23.07 to 40.71 days under different flooding conditions,and 18.78 to 28.88 days for different soils.Laccase is an efficient and safe agent for bioremediation of DDT-contaminated soil.展开更多
Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium C...Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium Cd chemical forms in two soil textural classes in Fars province-Iran at two soil water content(SWC)(flooded soil water content(FSWC)and field capacity soil water content(FCSWC))and study the kinetic modeling of Cd.Methods and materials:Variables were three levels of Cd(0,30 and 60 mg kg-1 of soil as CdSO4·8H2O),three levels of Zn(0,5 and 10 mg kg-1 of soil as Zn-EDTA)three level Incubation times(2,4 and eight weeks),two soil textural classes(clay and sandy clay loam)and two SWC.The randomized completed block design(RCBD)was used for this experiment.The Tessier sequential extraction method was used to determine the Cd concentration in(WsEx),(Fe-MnOx),(Car),(Om)and(Res)chemical forms.Results:In the FSWC,Zn reduced the Cd concentration in Fe-MnOx,Car and Om forms and increased the WsEx but had no significant effect on the Res form.Changes in the Cd chemical forms under the in-fluence of Zn in both soils followed a similar trend.In the FCSWC,Zn reduced the Cd concentration Car and Om forms and increased the Cd concentration in the Fe-MnOx and WsEx forms while had no sig-nificant effect on Res form in the sandy clay loam soil.In the clay soil adding Zn reduced the Cd con-centration in Car and Om fractions and increased the Fe-MnOx and Res forms while has no significant effect on WsEx form.The competitive transport and adsorption Interactions between these two ions caused the changing in the Cd concentration in its chemical forms.Zn reduces the Cd concentration in the forms which are easily released into the soil solution from where they can be absorbed by plants.The power function kinetic mode is the best fitted model which can describe the Cd adsorption in our soil samples.The clay and organic compounds control the Cd adsorption in soils.The higher rate of Cd adsorption in almost all shaking times shows that Cd has more ability to occupy the adsorption sites in soils.展开更多
基金supported by National Natural Science Foundation of China(Grant No.U2243227)the Science and Technology Program of Guangdong Province(No.2020B1515120079)National Flash Flood Investigation and Evaluation Project(Grant No.SHZH-IWHR-57).
文摘Flood is one of the most devastating natural hazards.Employing machine learning models to construct flood susceptibility maps has become a pivotal step for decision-makers in disaster prevention and management.Existing flood conditioning factors inadequately account for regional characteristics of flood in the depiction of topography,potentially leading to an overestimation of flood susceptibility in flat areas.Addressing this gap,this study proposes a novel flood conditioning factor,local convexity factor(LCF),to enhance the accuracy of flood susceptibility modeling.Initially,LCF is computed based on a standard normal Gaussian surface to highlight elevation variations in local terrain.Subsequently,LCF is applied to flood susceptibility modeling using seven machine learning models across four distinct basins.Comparative analysis is conducted between flood susceptibility maps with and without the application of LCF to evaluate its impact on flood susceptibility modeling.The results demonstrate that the proposed LCF can enhance the accuracy of flood susceptibility modeling to varying degrees,across the four basins investigated.The Fujiang basin exhibited the most substantial improvement,with its AUC improved from 0.861 to 0.886,Producer’s Agreement improved from 0.869 to 0.899,and Overall Agreement improved from 0.778 to 0.811.Comparation with hydrodynamic inundation maps shows that particularly in relatively flat terrain areas,flood susceptibility maps incorporating LCF offer more precise delineation between flood-prone and non-flood-prone zones.This research holds potential for widespread application in the prediction of flood susceptibility using machine learning models,providing a novel perspective for enhancing their accuracy.
基金the National Key Basic Research Special Foundation of China (No. G1999011700) Zhejiang Provincial Natural Science Foundation of China (No. Y305314).
文摘The variation of seedling characteristics under different water supply conditions is strongly associated with drought resistance in rice （Oryza sativa L.） and a better elucidation of its genetics is helpful for improving rice drought resistance. Ninety-six doubled-haploid （DH） rice lines of an indica and japonica cross were grown in both flooding and upland conditions and QTLs for morphological traits at seedling stage were examined using 208 restriction fragment length polymorphism （RFLP） and 76 microsatellite （SSR） markers. A total of 32 putative QTLs were associated with the four seedling traits： average of three adventitious root lengths （ARL）, shoot height （SH）, shoot biomass （SW）, and root to shoot dry weight ratio （RSR）. Five QTLs detected were the same under control and upland conditions. The ratio between the mean value of the seedling trait under upland and flooding conditions was used for assessing drought tolerance. A total of six QTLs for drought tolerance were detected. Comparative analysis was performed for the QTLs detected in this case and those reported from two other populations with the same upland rice variety Azucena as parent. Several identical QTLs for seedling elongation across the three populations with the positive alleles from the upland rice Azucena were detected, which suggests that the alleles of Azucena might be involved in water stress-accelerated elongation of rice under different genetic backgrounds. Five cell wall-related candidate genes for OsEXPI, OsEXP2, OsEXP4, EXT, and EGase were mapped on the intervals carrying the QTLs for seedling traits.
基金Supported by the Science and Technology Planning Project of Guangdong Province of China(2008B080701012)the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Ministry of Education of Chinathe Leading Academic Discipline Program of Phase-3 of"Project-211"for South China Agricultural University(2009B010100001)
文摘Biodegradation of 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane(DDT)in soil by laccase extract from white rot fungi under different experimental conditions was investigated.DDTs,which stands for the sum of p,p′-DDE,o,p′-DDT,p,p′-DDD and p,p′-DDT in soil was degraded efficiently,and the residue decreased rapidly during the first 15 days and then slowly during the period of 16-25 days.The biodegradation of DDTs in soil fitted the pseudo-first-order kinetics.For 5,10,15 and 25 days of incubation with laccase,the residue of DDTs in soil under different atmospheres was decreased by 20%-33%,34%-52%,41%-61%and 41%-69%respectively,under different flooding conditions that was decreased by 12%-17%,17%-30%,30%-45%and 35%-52%respectively, and for different soils that was decreased by 25%-34%,39%-53%,44%-58%and 47%-62%respectively.The half-life of DDTs in soil ranged from 15.07 to 32.95 days under O2,air or N2 atmospheres,23.07 to 40.71 days under different flooding conditions,and 18.78 to 28.88 days for different soils.Laccase is an efficient and safe agent for bioremediation of DDT-contaminated soil.
文摘Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium Cd chemical forms in two soil textural classes in Fars province-Iran at two soil water content(SWC)(flooded soil water content(FSWC)and field capacity soil water content(FCSWC))and study the kinetic modeling of Cd.Methods and materials:Variables were three levels of Cd(0,30 and 60 mg kg-1 of soil as CdSO4·8H2O),three levels of Zn(0,5 and 10 mg kg-1 of soil as Zn-EDTA)three level Incubation times(2,4 and eight weeks),two soil textural classes(clay and sandy clay loam)and two SWC.The randomized completed block design(RCBD)was used for this experiment.The Tessier sequential extraction method was used to determine the Cd concentration in(WsEx),(Fe-MnOx),(Car),(Om)and(Res)chemical forms.Results:In the FSWC,Zn reduced the Cd concentration in Fe-MnOx,Car and Om forms and increased the WsEx but had no significant effect on the Res form.Changes in the Cd chemical forms under the in-fluence of Zn in both soils followed a similar trend.In the FCSWC,Zn reduced the Cd concentration Car and Om forms and increased the Cd concentration in the Fe-MnOx and WsEx forms while had no sig-nificant effect on Res form in the sandy clay loam soil.In the clay soil adding Zn reduced the Cd con-centration in Car and Om fractions and increased the Fe-MnOx and Res forms while has no significant effect on WsEx form.The competitive transport and adsorption Interactions between these two ions caused the changing in the Cd concentration in its chemical forms.Zn reduces the Cd concentration in the forms which are easily released into the soil solution from where they can be absorbed by plants.The power function kinetic mode is the best fitted model which can describe the Cd adsorption in our soil samples.The clay and organic compounds control the Cd adsorption in soils.The higher rate of Cd adsorption in almost all shaking times shows that Cd has more ability to occupy the adsorption sites in soils.
