Straw return in situ,a common agronomic measure in China,has been widely used not only to increase crop yields and improve soil nutrients but also to remove polycyclic aromatic hydrocarbons(PAHs)from agricultural soil...Straw return in situ,a common agronomic measure in China,has been widely used not only to increase crop yields and improve soil nutrients but also to remove polycyclic aromatic hydrocarbons(PAHs)from agricultural soils.Nevertheless,the safety risks of food crops(i.e.,human health risk of wheat grains)grown in PAHs-contaminated agricultural soils amended with crop straw remain uncertain.A pot experiment was conducted in a PAHs-contaminated agricultural soil cultivated with winter wheat under different ratios of corn straw addition(0%(control,CK),1%,2.5%,and 5%,weight/weight).Results showed that corn straw addition significantly(P<0.05)decreased PAH concentrations in rhizosphere soil,roots,straws,and grains by 48.32%–50.01%,11.85%–42.67%,9.78%–28.03%,and 14.16%–31.67%,respectively,compared with CK,whereas the transfer factors of PAHs from roots to straws were significantly(P<0.05)increased.A correlation heatmap showed that PAH concentrations in roots,straws,and grains were positively(P<0.01)correlated with those in rhizosphere soil.These indicated that corn straw decreased PAH accumulation in winter wheat due to the increase of PAH dissipation in the rhizosphere soil,although it enhanced PAH transfer in winter wheat.The incremental lifetime cancer risk(ILCR)model indicated that corn straw significantly(P<0.05)decreased the human health risk of winter wheat grains by 29.73%–45.05%.Overall,corn straw apparently reduced PAH accumulation in winter wheat,ecological risk,and human health risk via enhancing PAH dissipation in the rhizosphere soil.These findings provide an important scientific basis and theoretical guidance for agricultural safety production.展开更多
For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by c...For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar,and maize straw biochar(MSB) for an entire growth period of winter wheat. Compared with no biochar control(CK), application of the three types of biochar significantly(P < 0.01) reduced grain PAH concentration, total equivalent concentration(TEC), and incremental lifetime cancer risk(ILCR), indicating that biochar application, especially MSB, reduced the risk of exposure to PAHs in wheat grain. Furthermore, all three types of biochar significantly(P < 0.05)reduced PAH uptake and accumulation in wheat roots and stems, probably because biochar application enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly(P < 0.05) reduced the concentration of PAHs in the rhizosphere soil by15.9%–33.7%. It was found that the degradation rate of high-molecular-weight(HMW) PAHs(5-and 6-ring PAHs) was significantly(P < 0.05) higher than that of low-molecular-weight(LMW) PAHs(2–4-ring PAHs) regardless of the type of biochar used. Additionally, all three types of biochar significantly increased the relative abundance of the dominant bacterial phyla and genera in soil. Redundancy and correlation analyses also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. This study indicated that biochar effectively reduced the health risk from dietary exposure to PAHs in wheat grains by increasing the abundance of bacteria related to PAH degradation, promoting the biodegradation of PAHs in the rhizosphere soil, and consequently reducing PAH uptake by wheat.展开更多
During the aging process,ferrihydrite was transformed into mineral mixtures composed of different proportions of ferrihydrite,goethite,lepidocrocite and hematite.Such a transformation may affect the fixed ability of a...During the aging process,ferrihydrite was transformed into mineral mixtures composed of different proportions of ferrihydrite,goethite,lepidocrocite and hematite.Such a transformation may affect the fixed ability of arsenic.In this study,the stability of Fe-As composites formed with As(Ⅴ)and the minerals aged for 0,1,4,10 and 30 days of ferrihydrite were systematically examined,and the effects of molar of ratios Fe/As were also clarified using kinetic methods combined with multiple spectroscopic techniques.The results indicated that As(Ⅴ)was rapidly adsorbed on minerals during the initial polymerization process,which delayed both the ferrihydrite conversion and the hematite formation.When the Fe/As molar ratio was 1.875 and 5.66,the As(Ⅴ)adsorbed by ferrihydrite began to release after 6 hr and 12 hr,respectively.The corresponding release amounts of As(Ⅴ)were 0.55 g/L and 0.07 g/L,and the adsorption rates were 92.43%and 97.50%at 60 days,respectively.However,the As(Ⅴ)adsorbed by the transformation products aged for 30 days of ferrihydrite began to release after adsorbed 30 days.The corresponding release amounts of As(Ⅴ)were 0.25 g/L and 0.03 g/L,and the adsorption rates were 84.23%and 92.18%after adsorbed 60 days,for the Fe/As=1.875 and 5.66,respectively.Overall,the combination of As(Ⅴ)with ferrihydrite and aged products transformed from a thermodynamically metastable phase to a dynamically stable state within a certain duration.Moreover,the aging process of ferrihydrite reduced the sorption ability of arsenate by iron(hydr)oxide but enhanced the stability of the Fe-As composites.展开更多
The effect of mulching with straw, white plastic film and black plastic film for improving soil water storage and on the soil properties was examined in a wheat-maize rotation system on Loess soil in northwestern Chin...The effect of mulching with straw, white plastic film and black plastic film for improving soil water storage and on the soil properties was examined in a wheat-maize rotation system on Loess soil in northwestern China. All the mulches improved the water storage to some extent and led to warmer soils. However, the organic C and total N contents of the soils declined significantly under the mulches, particularly the plastic film mulches,and this could have long-term detrimental effects on soil quality and the sustainability of the some mulching practices.展开更多
基金supported by the National Natural Science Foundation of China(Nos.41571456 and 42077325)the Natural Science Basic Research Program of Shaanxi,China(No.2023-JC-ZD-17).
文摘Straw return in situ,a common agronomic measure in China,has been widely used not only to increase crop yields and improve soil nutrients but also to remove polycyclic aromatic hydrocarbons(PAHs)from agricultural soils.Nevertheless,the safety risks of food crops(i.e.,human health risk of wheat grains)grown in PAHs-contaminated agricultural soils amended with crop straw remain uncertain.A pot experiment was conducted in a PAHs-contaminated agricultural soil cultivated with winter wheat under different ratios of corn straw addition(0%(control,CK),1%,2.5%,and 5%,weight/weight).Results showed that corn straw addition significantly(P<0.05)decreased PAH concentrations in rhizosphere soil,roots,straws,and grains by 48.32%–50.01%,11.85%–42.67%,9.78%–28.03%,and 14.16%–31.67%,respectively,compared with CK,whereas the transfer factors of PAHs from roots to straws were significantly(P<0.05)increased.A correlation heatmap showed that PAH concentrations in roots,straws,and grains were positively(P<0.01)correlated with those in rhizosphere soil.These indicated that corn straw decreased PAH accumulation in winter wheat due to the increase of PAH dissipation in the rhizosphere soil,although it enhanced PAH transfer in winter wheat.The incremental lifetime cancer risk(ILCR)model indicated that corn straw significantly(P<0.05)decreased the human health risk of winter wheat grains by 29.73%–45.05%.Overall,corn straw apparently reduced PAH accumulation in winter wheat,ecological risk,and human health risk via enhancing PAH dissipation in the rhizosphere soil.These findings provide an important scientific basis and theoretical guidance for agricultural safety production.
基金financially supported by the National Natural Science Foundation of China (Nos. 42077325 and 41571456)the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2019JZ-25)。
文摘For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar,and maize straw biochar(MSB) for an entire growth period of winter wheat. Compared with no biochar control(CK), application of the three types of biochar significantly(P < 0.01) reduced grain PAH concentration, total equivalent concentration(TEC), and incremental lifetime cancer risk(ILCR), indicating that biochar application, especially MSB, reduced the risk of exposure to PAHs in wheat grain. Furthermore, all three types of biochar significantly(P < 0.05)reduced PAH uptake and accumulation in wheat roots and stems, probably because biochar application enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly(P < 0.05) reduced the concentration of PAHs in the rhizosphere soil by15.9%–33.7%. It was found that the degradation rate of high-molecular-weight(HMW) PAHs(5-and 6-ring PAHs) was significantly(P < 0.05) higher than that of low-molecular-weight(LMW) PAHs(2–4-ring PAHs) regardless of the type of biochar used. Additionally, all three types of biochar significantly increased the relative abundance of the dominant bacterial phyla and genera in soil. Redundancy and correlation analyses also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. This study indicated that biochar effectively reduced the health risk from dietary exposure to PAHs in wheat grains by increasing the abundance of bacteria related to PAH degradation, promoting the biodegradation of PAHs in the rhizosphere soil, and consequently reducing PAH uptake by wheat.
基金the Agricultural Science and Tech-nology Innovation Program of the Chinese Academy of Agricul-tural Sciences(No.CAAS-ASTIP-2016-IEDA)。
文摘During the aging process,ferrihydrite was transformed into mineral mixtures composed of different proportions of ferrihydrite,goethite,lepidocrocite and hematite.Such a transformation may affect the fixed ability of arsenic.In this study,the stability of Fe-As composites formed with As(Ⅴ)and the minerals aged for 0,1,4,10 and 30 days of ferrihydrite were systematically examined,and the effects of molar of ratios Fe/As were also clarified using kinetic methods combined with multiple spectroscopic techniques.The results indicated that As(Ⅴ)was rapidly adsorbed on minerals during the initial polymerization process,which delayed both the ferrihydrite conversion and the hematite formation.When the Fe/As molar ratio was 1.875 and 5.66,the As(Ⅴ)adsorbed by ferrihydrite began to release after 6 hr and 12 hr,respectively.The corresponding release amounts of As(Ⅴ)were 0.55 g/L and 0.07 g/L,and the adsorption rates were 92.43%and 97.50%at 60 days,respectively.However,the As(Ⅴ)adsorbed by the transformation products aged for 30 days of ferrihydrite began to release after adsorbed 30 days.The corresponding release amounts of As(Ⅴ)were 0.25 g/L and 0.03 g/L,and the adsorption rates were 84.23%and 92.18%after adsorbed 60 days,for the Fe/As=1.875 and 5.66,respectively.Overall,the combination of As(Ⅴ)with ferrihydrite and aged products transformed from a thermodynamically metastable phase to a dynamically stable state within a certain duration.Moreover,the aging process of ferrihydrite reduced the sorption ability of arsenate by iron(hydr)oxide but enhanced the stability of the Fe-As composites.
基金supported by the National High-tech R&D Program of China (2013AA102904, 2011AA100503)the Sci-tech Coordination and Innovation Project of Shaanxi Province (2016KTZDNY03-06)+1 种基金Chinese "111" Project (B12007)supported by the Chinese Scholarship Council at Royal Agricultural University, UK
文摘The effect of mulching with straw, white plastic film and black plastic film for improving soil water storage and on the soil properties was examined in a wheat-maize rotation system on Loess soil in northwestern China. All the mulches improved the water storage to some extent and led to warmer soils. However, the organic C and total N contents of the soils declined significantly under the mulches, particularly the plastic film mulches,and this could have long-term detrimental effects on soil quality and the sustainability of the some mulching practices.
