Ectomycorrhizal(EM) fungi could form symbiosis with plant roots and participate in nutrient absorption; however, many EM species commonly found in forest soils, where phosphorus(P) concentration and availability are u...Ectomycorrhizal(EM) fungi could form symbiosis with plant roots and participate in nutrient absorption; however, many EM species commonly found in forest soils, where phosphorus(P) concentration and availability are usually very low, particularly in tropical and subtropical areas, have not yet been investigated for their efficiencies to mobilize soil P. In this study, fungal growth, P absorption,efflux of protons and organic acids, and soil P depletion by four isolates of EM fungi isolated either from acidic or calcareous soils were compared in pure liquid culture using soil as a sole P source. Boletus sp. 7(Bo 7), Lactarius deliciosus 3(Ld 3), and Pisolithus tinctorius 715(Pt 715) from acidic and P-deficient soils of southwestern China showed higher biomass and P concentration and accumulation than Cenococcum geophilum 4(Cg 4) from a calcareous soil of Inner Mongolia, northern China, after 4 weeks of liquid culture. Oxalate, malate, succinate, acetate, and citrate concentrations in the culture solutions varied significantly with fungal species,and oxalate accounted for 51.5%–91.4% of the total organic acids. Organic acids, particularly oxalate, in the culture solutions may lead to the solubilization of iron-bound P(Fe-P), aluminum-bound P(Al-P), and occluded P(O-P) from soil phosphates. Fungal species also varied greatly in proton efflux, which decreased the culture solution pH and may dissolve calcium-bound P(Ca-P) in soil.This could be the reason for the increment of both inorganic P in the culture solutions and Olsen P in the soil when EM fungi were present. Total inorganic P, the sum of Al-P, Fe-P, O-P, and Ca-P, in the culture solutions was positively correlated with the total concentration of organic acids in the culture solutions(r = 0.918*, n = 5), but negatively with both the total inorganic P in soil(r =-0.970**, n = 5) and the culture solution pH(r =-0.830*, n = 5). These suggested variable efficiencies of EM fungal species to mobilize inorganic P fractions from soil, which could make EM trees to utilize inorganic P in the same way like EM fungi and adapt to the soils with various P concentrations and availabilities.展开更多
Metallic glasses(MGs)have attracted great attention in wastewater treatment because of their high reactivity arising from amorphous structure,large residual stress and high density of low coordination sites.However,th...Metallic glasses(MGs)have attracted great attention in wastewater treatment because of their high reactivity arising from amorphous structure,large residual stress and high density of low coordination sites.However,the reactivity of MGs would gradually slow down with time due to the passivation of active sites by corrosion products,resulting in limited long-term reactivity,which is also an unsolved key issue for established crystalline zero valent iron(ZVI)technology.Here,such problems are successfully overcome by introducing nanoscale chemical inhomogeneities in Fe-based MG(Fe-MGI),which apparently contributes to local galvanic cell effect and accelerates electron transfer during degradation process.More importantly,the selective depletion of Fe0 causes local volume shrinkage and crack formation,leading to self-peeling of precipitated corrosion products and reacted regions.Thereby fresh low coordination sites could be continuously provided,counteracting the mass transport and reactivity deteriorating problem.Consequently,Fe-MGI demonstrates excellent long-term reactivity and self-refreshing properties even in neutral solution.The present results provide not only a new candidate but also a new route of designing ZVI materials for wastewater treatment.展开更多
基金Supported by the National Basic Research Program(973 Program)of China(No.2013CB27405)the National Natural Science Foundation of China(Nos.40771112 and 41171215)the Technology Innovation Program of Southwest University of China(No.Ky2009022)
文摘Ectomycorrhizal(EM) fungi could form symbiosis with plant roots and participate in nutrient absorption; however, many EM species commonly found in forest soils, where phosphorus(P) concentration and availability are usually very low, particularly in tropical and subtropical areas, have not yet been investigated for their efficiencies to mobilize soil P. In this study, fungal growth, P absorption,efflux of protons and organic acids, and soil P depletion by four isolates of EM fungi isolated either from acidic or calcareous soils were compared in pure liquid culture using soil as a sole P source. Boletus sp. 7(Bo 7), Lactarius deliciosus 3(Ld 3), and Pisolithus tinctorius 715(Pt 715) from acidic and P-deficient soils of southwestern China showed higher biomass and P concentration and accumulation than Cenococcum geophilum 4(Cg 4) from a calcareous soil of Inner Mongolia, northern China, after 4 weeks of liquid culture. Oxalate, malate, succinate, acetate, and citrate concentrations in the culture solutions varied significantly with fungal species,and oxalate accounted for 51.5%–91.4% of the total organic acids. Organic acids, particularly oxalate, in the culture solutions may lead to the solubilization of iron-bound P(Fe-P), aluminum-bound P(Al-P), and occluded P(O-P) from soil phosphates. Fungal species also varied greatly in proton efflux, which decreased the culture solution pH and may dissolve calcium-bound P(Ca-P) in soil.This could be the reason for the increment of both inorganic P in the culture solutions and Olsen P in the soil when EM fungi were present. Total inorganic P, the sum of Al-P, Fe-P, O-P, and Ca-P, in the culture solutions was positively correlated with the total concentration of organic acids in the culture solutions(r = 0.918*, n = 5), but negatively with both the total inorganic P in soil(r =-0.970**, n = 5) and the culture solution pH(r =-0.830*, n = 5). These suggested variable efficiencies of EM fungal species to mobilize inorganic P fractions from soil, which could make EM trees to utilize inorganic P in the same way like EM fungi and adapt to the soils with various P concentrations and availabilities.
基金financially supported by the National Natural Science Foundation of China (NSFC, 51871129 and 51571127)the National Key Basic Research and Development Programme (2016YFB0300502)the Natural Science Foundation of Jiangsu Province (BK20190480)
文摘Metallic glasses(MGs)have attracted great attention in wastewater treatment because of their high reactivity arising from amorphous structure,large residual stress and high density of low coordination sites.However,the reactivity of MGs would gradually slow down with time due to the passivation of active sites by corrosion products,resulting in limited long-term reactivity,which is also an unsolved key issue for established crystalline zero valent iron(ZVI)technology.Here,such problems are successfully overcome by introducing nanoscale chemical inhomogeneities in Fe-based MG(Fe-MGI),which apparently contributes to local galvanic cell effect and accelerates electron transfer during degradation process.More importantly,the selective depletion of Fe0 causes local volume shrinkage and crack formation,leading to self-peeling of precipitated corrosion products and reacted regions.Thereby fresh low coordination sites could be continuously provided,counteracting the mass transport and reactivity deteriorating problem.Consequently,Fe-MGI demonstrates excellent long-term reactivity and self-refreshing properties even in neutral solution.The present results provide not only a new candidate but also a new route of designing ZVI materials for wastewater treatment.
