The biodegradation of polymeric biocomposites formed from epoxidized linseed oil and various types of fillers(pine needles,pine bark,grain mill waste,rapeseed cake)and a control sample without filler was studied durin...The biodegradation of polymeric biocomposites formed from epoxidized linseed oil and various types of fillers(pine needles,pine bark,grain mill waste,rapeseed cake)and a control sample without filler was studied during 180 days of exposure to two types of forest soil:deciduous and coniferous.The weight loss,morphological,and structural changes of polymer composites were noticed after 180 days of the soil burial test.The greatest weight loss of all tested samples was observed in coniferous forest soil(41.8%–63.2%),while in deciduous forest soil,it ranged between 37.7%and 42.3%.The most significant changes in the intensities of the signals evaluated by attenuated total reflectance infrared spectroscopy,as well as morphological changes determined by scanning electron microscopy,were assessed for polymer composite with rapeseed cake and specimen without filler in coniferous forest soil and are in a good agreement with weight loss results.Whereas significantly lower changes in weight loss,morphology,and structure of polymeric film with pine bark were noticed in both soils.It was suggested that fungi of Trichoderma,Penicillium,Talaromyces and Clonostachys genera are the possible soil microorganisms that degrade linseed oil-based cross-linked polymer composites.Moreover,the novel polymer composites have the potential to be an environmentally friendly alternative to petroleum-based mulching films.展开更多
Croplands are often suffering from sand burial in dry regions of northern China. For studying this phenomenon, we carried out a case study of field experiment including four sand burial levels, i.e. shallow （1-3 cm）...Croplands are often suffering from sand burial in dry regions of northern China. For studying this phenomenon, we carried out a case study of field experiment including four sand burial levels, i.e. shallow （1-3 cm）, moderate （8-12 cm） and deep （15-20 cm） sand burials, and no sand burial （control, CK）, in a typical agro-pastoral transitional zone in Naiman Banner of eastern Inner Mongolia. The aim of this study was to assess the impacts of sand burial on maize （Zea rnays L.） productivity and the soil quality along a gradient of burial depths. Results showed that there was a strong negative effect of sand burial on maize productivity and soil quality, which significantly declined （P〈0.05） under moderate and deep sand burial treatments. In comparison with the CK, the maize yield and above-ground biomass reduced by 47.41% and 39.47%, respectively. The soil silt and clay, soil water, soil organic carbon and total nitrogen contents under deep sand burial decreased by 67.85%, 40.32%, 86.52% and 82.11%, respectively, while microbial biomass carbon, microbial abundance and enzyme activity decreased by 89.78%, 42.28%-79.66% and 69.51%-97.71%, respectively. There was no significant effect on crop productivity and soil quality with shallow sand burial treatment. The correlations analysis showed that there was significant positive correlations of both maize yield and above-ground biomass with soil silt and clay, soil organic carbon and total nitrogen contents, pH, electrical conductivity, soil water content, microbial abundance and biomass and all tested soil enzyme activities. Stepwise regression analysis indicated that soil water and total nitrogen contents, urease, cellobiohydrolase and peroxidase activities were key determining factors for maize productivity. This combination of factors explains reason of the decreased maize productivity with deep sand burial. We found that degradation of cropland as a result of sand burial changed soil physical-chemical properties and soil enzyme activities in the plow layer, and decreased overall maize productivity. Furthermore, decreased soil enzyme activity was a better indicator to predict sandy cropland degradation.展开更多
An artificial seed bank study was conducted at Pendleton, SC, USA, to investigate the persistence of Palmer amaranth seeds buried uniformly across a 10-cm depth in soil inside polyvinyl chloride (PVC) cylindrical pipe...An artificial seed bank study was conducted at Pendleton, SC, USA, to investigate the persistence of Palmer amaranth seeds buried uniformly across a 10-cm depth in soil inside polyvinyl chloride (PVC) cylindrical pipes over 4 years. The experiment was conducted using a split-plot design, with year as the main plot factor and with or without soil disturbance (shallow tillage to a depth of 10 cm) as the subplot factor. Annual soil disturbance through tillage in the spring stimulated emergence during the first and second year after burial. A total of 0.5% to 0.8% of the seed bank emerged during the 4-yr burial period, and 99% or more of the 4-yr total emergence occurred during the first two years of burial. Seeds retrieved from 0 to 5 cm and 5 to 10 cm depths did not differ in viability. Soil disturbance influenced the decline of the artificial seed bank at least in the first year, with fewer viable seeds remaining in annually-disturbed plots. Regardless of soil disturbance, a small fraction of seeds (0.01% to 0.03% of original seed bank) remained viable in the soil after four years of burial. In conclusion, Palmer amaranth seeds buried across a 10 cm soil depth in the artificial seed bank had low persistence, which implies that burial may aid management of the weed seed bank.展开更多
为了探究炸药在土壤-混凝土复合防护工事的表层土壤的爆炸开坑情况及最佳爆破深度,在土壤-混凝土复合介质与单土壤介质两种条件下,对JH-2圆柱形装药在不同埋药深度中的爆炸进行了数值模拟。研究了药柱爆炸后爆坑的形成和发展规律。在8...为了探究炸药在土壤-混凝土复合防护工事的表层土壤的爆炸开坑情况及最佳爆破深度,在土壤-混凝土复合介质与单土壤介质两种条件下,对JH-2圆柱形装药在不同埋药深度中的爆炸进行了数值模拟。研究了药柱爆炸后爆坑的形成和发展规律。在8种不同埋药深度及有、无混凝土层的情况下,对比分析了爆坑的形状及尺寸。通过理论计算,得到80 g JH-2药柱在土中抛掷爆破时爆坑的最大半径及相应的埋药深度。对比研究了相同药量、不同埋药深度时土壤与土壤-混凝土两种工况下的爆坑形状与尺寸大小。结果表明:混凝土层反射的冲击波可以对土壤层表面进行二次破坏,使得爆坑的崩落区明显变大。通过试验验证发现,在埋药深度为350 mm时,80 g JH-2圆柱形装药可以在土壤-混凝土复合介质靶中形成一个大且稳定的爆坑,爆坑的形状、尺寸与仿真和理论计算结果吻合。展开更多
文摘The biodegradation of polymeric biocomposites formed from epoxidized linseed oil and various types of fillers(pine needles,pine bark,grain mill waste,rapeseed cake)and a control sample without filler was studied during 180 days of exposure to two types of forest soil:deciduous and coniferous.The weight loss,morphological,and structural changes of polymer composites were noticed after 180 days of the soil burial test.The greatest weight loss of all tested samples was observed in coniferous forest soil(41.8%–63.2%),while in deciduous forest soil,it ranged between 37.7%and 42.3%.The most significant changes in the intensities of the signals evaluated by attenuated total reflectance infrared spectroscopy,as well as morphological changes determined by scanning electron microscopy,were assessed for polymer composite with rapeseed cake and specimen without filler in coniferous forest soil and are in a good agreement with weight loss results.Whereas significantly lower changes in weight loss,morphology,and structure of polymeric film with pine bark were noticed in both soils.It was suggested that fungi of Trichoderma,Penicillium,Talaromyces and Clonostachys genera are the possible soil microorganisms that degrade linseed oil-based cross-linked polymer composites.Moreover,the novel polymer composites have the potential to be an environmentally friendly alternative to petroleum-based mulching films.
基金financially supported by the National Natural Science Foundation of China (41401620,41271007)the Hundred Talents Program of Chinese Academy of Sciences (Y451H31001,Y551821001)the Key Laboratory of Desert and Desertification Foundation from Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences (KLDD-2014-010)
文摘Croplands are often suffering from sand burial in dry regions of northern China. For studying this phenomenon, we carried out a case study of field experiment including four sand burial levels, i.e. shallow （1-3 cm）, moderate （8-12 cm） and deep （15-20 cm） sand burials, and no sand burial （control, CK）, in a typical agro-pastoral transitional zone in Naiman Banner of eastern Inner Mongolia. The aim of this study was to assess the impacts of sand burial on maize （Zea rnays L.） productivity and the soil quality along a gradient of burial depths. Results showed that there was a strong negative effect of sand burial on maize productivity and soil quality, which significantly declined （P〈0.05） under moderate and deep sand burial treatments. In comparison with the CK, the maize yield and above-ground biomass reduced by 47.41% and 39.47%, respectively. The soil silt and clay, soil water, soil organic carbon and total nitrogen contents under deep sand burial decreased by 67.85%, 40.32%, 86.52% and 82.11%, respectively, while microbial biomass carbon, microbial abundance and enzyme activity decreased by 89.78%, 42.28%-79.66% and 69.51%-97.71%, respectively. There was no significant effect on crop productivity and soil quality with shallow sand burial treatment. The correlations analysis showed that there was significant positive correlations of both maize yield and above-ground biomass with soil silt and clay, soil organic carbon and total nitrogen contents, pH, electrical conductivity, soil water content, microbial abundance and biomass and all tested soil enzyme activities. Stepwise regression analysis indicated that soil water and total nitrogen contents, urease, cellobiohydrolase and peroxidase activities were key determining factors for maize productivity. This combination of factors explains reason of the decreased maize productivity with deep sand burial. We found that degradation of cropland as a result of sand burial changed soil physical-chemical properties and soil enzyme activities in the plow layer, and decreased overall maize productivity. Furthermore, decreased soil enzyme activity was a better indicator to predict sandy cropland degradation.
文摘An artificial seed bank study was conducted at Pendleton, SC, USA, to investigate the persistence of Palmer amaranth seeds buried uniformly across a 10-cm depth in soil inside polyvinyl chloride (PVC) cylindrical pipes over 4 years. The experiment was conducted using a split-plot design, with year as the main plot factor and with or without soil disturbance (shallow tillage to a depth of 10 cm) as the subplot factor. Annual soil disturbance through tillage in the spring stimulated emergence during the first and second year after burial. A total of 0.5% to 0.8% of the seed bank emerged during the 4-yr burial period, and 99% or more of the 4-yr total emergence occurred during the first two years of burial. Seeds retrieved from 0 to 5 cm and 5 to 10 cm depths did not differ in viability. Soil disturbance influenced the decline of the artificial seed bank at least in the first year, with fewer viable seeds remaining in annually-disturbed plots. Regardless of soil disturbance, a small fraction of seeds (0.01% to 0.03% of original seed bank) remained viable in the soil after four years of burial. In conclusion, Palmer amaranth seeds buried across a 10 cm soil depth in the artificial seed bank had low persistence, which implies that burial may aid management of the weed seed bank.
文摘为了探究炸药在土壤-混凝土复合防护工事的表层土壤的爆炸开坑情况及最佳爆破深度,在土壤-混凝土复合介质与单土壤介质两种条件下,对JH-2圆柱形装药在不同埋药深度中的爆炸进行了数值模拟。研究了药柱爆炸后爆坑的形成和发展规律。在8种不同埋药深度及有、无混凝土层的情况下,对比分析了爆坑的形状及尺寸。通过理论计算,得到80 g JH-2药柱在土中抛掷爆破时爆坑的最大半径及相应的埋药深度。对比研究了相同药量、不同埋药深度时土壤与土壤-混凝土两种工况下的爆坑形状与尺寸大小。结果表明:混凝土层反射的冲击波可以对土壤层表面进行二次破坏,使得爆坑的崩落区明显变大。通过试验验证发现,在埋药深度为350 mm时,80 g JH-2圆柱形装药可以在土壤-混凝土复合介质靶中形成一个大且稳定的爆坑,爆坑的形状、尺寸与仿真和理论计算结果吻合。
