ABSTRACT
In order to study the safe utilization of acid cadmium ï¼Cdï¼ contaminated soilï¼ light and moderate Cd-contaminated farmland in Shangluoï¼ Shaanxi Province was taken as the research objectï¼ and limeï¼ biocharï¼ and calcium magnesium phosphate fertilizer were applied. Through the wheat-maize rotation experimentï¼ the safe utilization effect of different amounts of passivator on Cd-contaminated soil was exploredï¼ and the best ratio of passivator was selected. The results showed thatï¼ â the soil quality could be improved to varying degrees by applying the passivator. â¡ After the application of amendmentsï¼ the grain yield of wheat and maize increased to different degrees. ⢠The lime 2 340 kg·hm-2 ï¼C3ï¼ treatment had the best effectï¼ which increased the soil pH of wheat and corn by 1.453 and 1.717 unitsï¼ respectivelyï¼ and reduced the available Cd content by 34.38% and 30.20%ï¼ respectively. ⣠The application of biochar 1 800 kg·hm-2 ï¼B2ï¼ treatment had the best effect on reducing the Cd contents in wheat rootsï¼ strawsï¼ and grainsï¼ which were significantly reduced by 53.60%ï¼ 38.86%ï¼ and 52.96%ï¼ respectivelyï¼ compared with that in CK. The Cd content in wheat grains was reduced to 0.09 mg·kg-1ï¼ which was lower than the limit value of wheat Cd ï¼0.1 mg·kg-1ï¼ specified in the "National food safety standard food pollutant limit" ï¼GB 2762-2017ï¼. The application of the biochar 1 260 kg·hm-2 ï¼B1ï¼ treatment had the best comprehensive effect on reducing the Cd contents of maize rootsï¼ strawsï¼ and grainsï¼ which were significantly reduced by 43.74%ï¼ 53.20%ï¼ and 94.57%ï¼ respectivelyï¼ compared with that in CK. The Cd content of maize grains was reduced to 0.001 9 mg·kg-1ï¼ which was far lower than the limit value of maize Cd ï¼0.1 mg·kg-1ï¼ specified in the "National food safety standard food pollutant limit" ï¼GB 2762-2017ï¼. Thereforeï¼ under the conditions of the field experimentï¼ considering the influence of various indexesï¼ biochar had the best effect on farmland soil in the wheat-maize rotation area with mild to moderate Cd pollution.
Subject(s)
Calcium Compounds , Environmental Pollutants , Oryza , Oxides , Soil Pollutants , Farms , Cadmium/analysis , Soil Pollutants/analysis , Charcoal/chemistry , Soil/chemistry , TriticumABSTRACT
Fires lead to dramatic shifts in ecosystems and have a large impact on the biota. Soil organisms, especially soil fauna, are often used as indicators of environmental change. At present, minimal attention has been paid to using soil fauna as an indicator of environmental change after a fire. Here, a field survey of burnt herbaceous vegetation in semi-arid areas was conducted to determine the response of soil arthropods to fire and their short-term recovery after fire. Overall, the abundance and biomass of soil arthropods was more sensitive to fire than the number of groups. The number of soil arthropod groups, especially the dominant groups (mites and springtails), was not significantly affected by wildfires. At the unburned site, soil arthropod abundance showed significant seasonal shifts that may be related to the vegetation properties, temperature, and precipitation caused by seasonal changes. In contrast, soil arthropods at the burnt sites showed a delayed recovery and had only reached 56%-82%, 17%-54%, and 91%-190% of the biomass in the unburnt forest at the 3, 6, and 9 months after the burning event. Our findings of soil arthropod abundance changes in the present study suggest that fire-induced changes in soil and vegetation properties (e.g., AN, LT, and VC) were crucial factors for the changes in soil arthropod abundance in this semi-arid grassland. We conclude that fire disturbance reduces the seasonal sensitivity of soil arthropods by altering their habitat. This study furthers our understanding of wildfire impact recovery by documenting the short-term temporal dynamics of soil arthropods.