Excess phosphorus (P) from agricultural soils contributes to eutrophication in water bodies.Samples (n=60) were taken from sites where rice paddies have been converted to vegetable fields for 0,< 10,10-20,and > ...Excess phosphorus (P) from agricultural soils contributes to eutrophication in water bodies.Samples (n=60) were taken from sites where rice paddies have been converted to vegetable fields for 0,< 10,10-20,and > 20 years and analyzed for five inorganic P (Pi) fractions,three organic P(Po) fractions,and several soil parameters to investigate how land use conversion affects Pi and Po fractions in a peri-urban area of China with soils characteristic of many agricultural areas of Asia.Significant increases of 33,281,293,and 438 mg kg 1 were found for soluble and loosely bound Pi (SL-Pi),aluminum-bound Pi (Al-Pi),calcium-bound P i (Ca-Pi),and iron-bound Pi (Fe-Pi),respectively,after conversion from rice paddies to vegetable fields.Most of the increase in Pi was in the form of Fe-Pi,which increased from 8% of total P (TP) on paddy soil to 31% on the soil with > 20-year vegetable cultivation,followed by Al-Pi,which increased from 2% to 19% of TP.For Po fractions,there was no significant change in P concentrations.The conversion of land use from paddy fields to high intensity vegetable fields was causing significant changes in soil P fractions.Management practices were causing a buildup of soil P,primarily in the Fe-Pi fraction,followed by Ca-Pi and Al-Pi fractions.If current trends continue,a 30%-70% increase in TP could be expected in the next 20 years.Farmers in the area should reduce P application and use to maximize P uptake.展开更多
To show the vegetation succession interaction with soil properties, microbial biomass, basal respiration, and enzyme activities in different soil layers (0-60 cm) were determined in six lands, i.e., 2-, 7-, 11-, 20-, ...To show the vegetation succession interaction with soil properties, microbial biomass, basal respiration, and enzyme activities in different soil layers (0-60 cm) were determined in six lands, i.e., 2-, 7-, 11-, 20-, and 43-year-old abandoned lands and one native grassland, in a semiarid hilly area of the Loess Plateau. The results indicated that the successional time and soil depths affected soil microbiological parameters significantly. In 20-cm soil layer, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), MBC/MBN, MBC to soil organic carbon ratio (MBC/SOC), and soil basal respiration tended to increase with successional stages but decrease with soil depths. In contrast, metabolic quotient (qCO 2 ) tended to decrease with successional stages but increase with soil depths. In addition, the activities of urease, catalase, neutral phosphatase, β-fructofuranosidase, and carboxymethyl cellulose (CMC) enzyme increased with successional stages and soil depths. They were significantly positively correlated with microbial biomass and SOC (P < 0.5), whereas no obvious trend was observed for the polyphenoloxidase activity. The results indicated that natural vegetation succession could improve soil quality and promote ecosystem restoration, but it needed a long time under local climate conditions.展开更多
To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions,and to evaluate the mean Gibbs free binding and adsorption energies of various cati...To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions,and to evaluate the mean Gibbs free binding and adsorption energies of various cations on particles of red soil and latosol,clay fractions smaller than 2 μm were separated from samples of the two variable-charge soils.Ferric oxides were removed from part of the clay fractions,which were then saturated with various chlorides(NaCl,KCl,CaCl2,CdCl2 or LaCl3).Electrical conductivities(EC) of dilute suspensions of the original and of the iron oxides-free clay fractions in deionized water were measured with the SHP-2 short high-voltage pulse apparatus,which enables measurement of the Wien effect at field strengths(E) from 14 to 250 kV cm-1.The Wien effect(EC-E) curves revealed EC increases of red soil suspensions between 14 and 200 kV cm-1,of 8.3,8.4,12.1,5.9,and 1.2 μS cm-1 for NaCl,KCl,CaCl2,CdCl2,and LaCl3,respectively,reflecting the differing interactions with the various cations and chloride.The EC increments with the iron-free red soil suspensions were higher,being 29.7,17.2,and 15.3 μS cm-1 for NaCl,CaCl2,and CdCl2,respectively.In the natural latosol suspensions the EC increments were practically zero,whereas in the iron-free fractions there were significant EC increments of 10.3,5.7,5.0,and 1.6 μS cm-1 for NaCl,CaCl2,CdCl2,and LaCl3,respectively.展开更多
This paper reports the dynamic changes of soil and water loss in the red soil region of Southern China since the 1950s. The red soil region covers eight provinces: Jiangxi, Zhejiang, Fujian, Anhui, Hubei, Hunan, Guang...This paper reports the dynamic changes of soil and water loss in the red soil region of Southern China since the 1950s. The red soil region covers eight provinces: Jiangxi, Zhejiang, Fujian, Anhui, Hubei, Hunan, Guangdong and Hainan. From the 1950s to 1986, the annual rate of soil erosion increased by 3.4%. From 1986 to 1996 and from 1996 to 2000, the annual rates of soil erosion decreased by 2.0% and 0.32%, respectively. Field surveys showed that from 2000 to 2005, the area of soil and water loss decreased annually by 1.2%. This decrease was a result of large-scale erosion control activities across China. Although the eroded soil has been restored, the restoration process is very slow and full restoration will take a long time. Our report suggests that controlling soil and water loss is a challenging task, and additional measures must be taken to effectively control the soil erosion in the red soil region.展开更多
This study investigated the e?ect of cold helium plasma treatment on seed germination, growth and yield of wheat. The e?ects of di?erent power of cold plasma on the germination of treated wheat seeds were studied. We ...This study investigated the e?ect of cold helium plasma treatment on seed germination, growth and yield of wheat. The e?ects of di?erent power of cold plasma on the germination of treated wheat seeds were studied. We found that the treatment of 80 W could significantly improve seed germination potential(6.0%) and germination rate(6.7%) compared to the control group. Field experiments were carried out for wheat seeds treated with 80 W cold plasma. Compared with the control, plant height(20.3%), root length(9.0%) and fresh weight(21.8%) were improved significantly at seedling stage. At booting stage, plant height, root length, fresh weight, stem diameter, leaf area and leaf thickness of the treated plant were respectively increased by 21.8%, 11.0%, 7.0%, 9.0%, 13.0% and 25.5%. At the same time, the chlorophyll content(9.8%), nitrogen(10.0%) and moisture content(10.0%) were higher than those of the control, indicating that cold plasma treatment could promote the growth of wheat. The yield of treated wheat was 7.55 t · ha-1, 5.89% more than that of the control. Therefore, our results show that cold plasma has important application prospects for increasing wheat yield.展开更多
The effects of low-vacuum helium cold plasma treatment on the seed germination,plant growth and yield of oilseed rape(Brassica napus L.cv.Zhongshuang 9) were investigated.Seeds were exposed to low-vacuum helium cold p...The effects of low-vacuum helium cold plasma treatment on the seed germination,plant growth and yield of oilseed rape(Brassica napus L.cv.Zhongshuang 9) were investigated.Seeds were exposed to low-vacuum helium cold plasma ranging from 0–120 W for 15 s.Cold plasma increased the germination,plant growth and yield of oilseed rape,and the treatment of 100 W provided the best result.The germination rate,germination and vigor indices,and uniformity of emergence were improved by cold plasma treatment.Cold plasma raised the relative conductivity and water uptake,and reduced the apparent contact angle.The characteristics of plant growth,including plant height,stem diameter,dry weights of shoot and root at the seedling,bolting and flowering stages were increased by the cold plasma treatment.Yield components,including pod numbers per plant and 1000 seed weights were increased by the cold plasma treatment.Furthermore,the yield per plant increased by 28.20%.These results suggest that cold plasma treatment has the potential to improve the yield of oilseed rape through the enhancement of permeability,wettability and capacity of water uptake of the seeds,seed germination and plant growth.展开更多
Brassica napus L.(B.napus)is an important oil crop worldwide and it rapidly accumulates oil at late stage of seed maturation.However,little is known about the cellular mechanism of oil accumulation and seed color chan...Brassica napus L.(B.napus)is an important oil crop worldwide and it rapidly accumulates oil at late stage of seed maturation.However,little is known about the cellular mechanism of oil accumulation and seed color changes during the late stage of rapeseed development.Here,we analyzed the ultrastructure of seed coat,aleurone and cotyledon in embryos of B.napus from 25 to 70 days after flowering(DAF).The pigments,which were deposited on the cell wall of palisade cells in seed coat,determined dark black color of rapeseed.The chloroplasts degenerated into non-photosynthetic plastids which caused the green cotyledon to turn into yellow.The chloroplasts in aleurone and cotyledon cells respectively degenerated into remnants without inner and outer envelope membranes and ecoplasts with intact inner and outer envelope membranes.From 40 to 70 DAF,there were degraded chloroplasts without thylakoid,oil bodies contacting with plastids or protein bodies,big starch deposits of chloroplasts degrading into small particles then disappearing,and small endoplasmic reticulum(ER)in aleurone and cotyledon cells.Additionally,there were decreases of chlorophyll content and dramatic increases of oil content in rapeseed.These results suggested that the rapid oil accumulation was independent on the NADPH synthesized by photosynthesis of chloroplasts and probably utilized other sources of reductant,such as the oxidative pentose phosphate pathway during the late stage of rapeseed development.The triacylglycerol assembly presumably utilizes the enzymes in the plastid,cytosol or oil body of cotyledon and aleurone cells.展开更多
The global soil environment has been under increasing pressure due to rapid industrialization and urbanization,along with intensive farming on arable land.In particular,the soil environmental quality in China is deter...The global soil environment has been under increasing pressure due to rapid industrialization and urbanization,along with intensive farming on arable land.In particular,the soil environmental quality in China is deteriorating in a rapid pace according to the'National Soil Pollution Survey'by the Ministry of Environmental Protection and the Ministry of Land and Resources of China(released on April 17,2014).展开更多
The biosurfactants rhamnolipids and the “soil ecosystem engineers” earthworms are often used to remediate contaminated soils. However, the effects of rhamnolipids on earthworm intestinal flora and microbial communit...The biosurfactants rhamnolipids and the “soil ecosystem engineers” earthworms are often used to remediate contaminated soils. However, the effects of rhamnolipids on earthworm intestinal flora and microbial community in soil containing earthworms are not clearly understood. In our study, a 21-d microcosm experiment was carried out to reveal the effects of rhamnolipids on microbial abundance, composition, and metabolism, as well as contaminant degradation capacity. Both rhamnolipids and earthworms had positive effects on soil bacteria. Rhamnolipid-amended soil(RT) showed higher bacterial abundance and metabolic activity than earthworm-amended soil(ET), while the improvement in bacterial composition and contaminant degradation capacity by rhamnolipids was lower than that by earthworms. Notably, these effects were further amplified by the combined treatment of rhamnolipids and earthworms(RET). Specifically, the bacterial abundance(log-transferred) increased from 9.5 copies g-1in the control with no addition to 10.3, 10.6, and 11.1 copies g-1in ET, RT, and RET, respectively. Compared to ET, the relative abundance of the dominant phylum, Proteobacteria, increased from 41.66% to 51.67% in RET,and more pollutant-degrading bacteria were also enriched in RET. Therefore, the increases in bacterial abundance and contaminant-degrading bacteria led to the following ranking of soil dioxin removal rate: RET(77.28%) > ET(59.83%) > RT(24.65%) > control(4.71%). Moreover, the addition of rhamnolipids enhanced the abundance of bacterial functional genes involved in metabolism and environmental information processing. In addition, the composition and diversity of bacteria in the gut of earthworms were conspicuously affected by rhamnolipids, and the relative abundance of Microbacterium and Shewanella increased significantly(P < 0.05). Therefore, this study revealed that rhamnolipids remarkably influenced the abundance, composition, and metabolism of the microbial community in earthworm gut, further promoting the degradation rate of dioxin, providing theoretical support for optimizing the combined application of rhamnolipids and earthworms in soil bioremediation engineering and for the assessment of the ecological impact of rhamnolipids.展开更多
With global climate change, soil drying-rewetting(DRW) events have intensified and occurred frequently on the Loess Plateau of China. However, the extent to which the DRW cycles with different wetting intensities and ...With global climate change, soil drying-rewetting(DRW) events have intensified and occurred frequently on the Loess Plateau of China. However, the extent to which the DRW cycles with different wetting intensities and cycle numbers alter microbial community and respiration is barely understood. Here,indoor DRW one and four cycles treatments were implemented on soil samples obtained from the Loess Plateau, involving increase of soil moisture from10% water-holding capacity(WHC) to 60% and 90% WHC(i.e., 10%–60% and 10%–90% WHC, respectively). Constant soil moistures of 10%, 60%,and 90% WHC were used as the controls. The results showed that bacterial diversity and richness decreased and those of fungi remained unchanged under DRW treatments compared to the controls. Under all moisture levels, Actinobacteriota and Ascomycota were the most dominant bacterial and fungal phyla,respectively. The bacterial network was more complex than that of fungi, indicating that bacteria had a greater potential for interaction and niche sharing under DRW treatments. The pulse of respiration rate declined as the DRW cycle increased under 10%–60% WHC, but remained similar for different cycles under 10%–90% WHC. Moreover, the DRW treatments reduced the overall carbon loss, and the direct carbon release under 10%–60% WHC was larger than that under 10%–90% WHC. The cumulative CO_(2) emissions after four DRW cycles were significantly positively correlated with microbial biomass carbon and negatively correlated with fungal richness(Chao 1).展开更多
Ion-absorbed rare earth mines,leached in situ,retain a large amount of ammonium nitrogen(NH4–N)that continuously releases into the surrounding environments.However,quantitative descriptions and predictions of the tra...Ion-absorbed rare earth mines,leached in situ,retain a large amount of ammonium nitrogen(NH4–N)that continuously releases into the surrounding environments.However,quantitative descriptions and predictions of the transport of NH4–N across mining area with hill slopes are not fully established.Here,laboratory column experiments were designed with an inclined slope(a sand box)to examine the spatial temporal transport of NH4–N in soils collected from the ionic rare earth elements(REE)mining area.An HYDRUS-2D model simulation of the experimental data over time showed that soils had a strong adsorption capacity toward NH4–N.Chemical non-equilibrium model(CNEM)could well simulate the transport of NH4–N through the soil-packed columns.The simulation of the transport-adsorption processes at three flow rates of leaching agents revealed that low flow rate enabled a longer residence time and an increased NH4-N adsorption,but reduced the extraction efficiency for REE.During the subsequent rainwater washing process,the presence of slope resulted in the leaching of NH4–N on the surface of the slope,while the leaching of NH4–N deep inside the column was inhibited.Furthermore,the high-intensity rainfall significantly increased the leaching,highlighting the importance of considering the impact of extreme weather conditions during the leaching process.Overall,our study advances the understanding of the transport of NH4–N in mining area with hills,the impact of flow rates of leaching agents and precipitation intensities,and presents as a feasible modeling method to evaluate the environmental risks of NH4–N pollution during and post REE in situ mining activities.展开更多
Altered drying-rewetting(DRW)procedures due to climate change may influence soil microbial properties and microbially-mediated carbon cycling in arid and semi-arid regions.However,the effects of DRW of different inten...Altered drying-rewetting(DRW)procedures due to climate change may influence soil microbial properties and microbially-mediated carbon cycling in arid and semi-arid regions.However,the effects of DRW of different intensities on the microbial properties and respiration are not well understood.Thus,the responsive patterns of microbial communities and carbon mineralization in agriculture soil on the Chinese Loess Plateau to DRW treatments with different wetting intensities(5%-25% and 5%-36%)and frequency(1-cycle to 4-cycle)were investigated.Continuous moisture levels of 5%,25% and 36% were used as control.Results revealed that the reduction of bacterial diversity and richness were greater for 5%-36% than 5%-25% treatment,while diversity of fungi was similar for different wetting intensities.Bacterial communities became clustered by wetting intensity rather than cycle number,however fungal community was unaffected by DRW.The complexity of bacterial co-occurrence network increased because of higher nodes,edges,average degree,diameter and average cluster coefficient after 4-cycles,and the interaction was more complex after 1-cycle for fungi.Rewetting caused a pulse-like increase of respiration rate,and the pulse amplitude was greater for DRW with high rewetting intensity and decreased with the increase of cycle number.The cumulative CO_(2) emission for DRW treatments was lower than that for the continuous moisture conditions.The net reduction of carbon release for 5%-36% treatment was 1.18 times higher than that for 5%-25% treatment.Our study provides experimental evidence of the positive potential of DRW processes for maintaining soil carbon stock in an agriculture system on the Loess Plateau.展开更多
Di-(2-ethylhexyl) phthalate(DEHP) is a high-molecular-weight phthalate ester(PAE) that has been widely used in the manufacture of polyvinylchloride and contributes to environmental pollution.The objectives of the pres...Di-(2-ethylhexyl) phthalate(DEHP) is a high-molecular-weight phthalate ester(PAE) that has been widely used in the manufacture of polyvinylchloride and contributes to environmental pollution.The objectives of the present study were to isolate a DEHP degrader that can utilize DEHP as a carbon source and to investigate its capacity to biodegrade DEHP in both liquid culture and soil.A bacterial strain WJ4 was isolated from an intensively managed vegetable soil,which was contaminated with PAEs.The strain WJ4 was affiliated to the genus Rhodococcus and was able to remove DEHP from soil effectively.A period of only 7 d was required to degrade about 96.4%of DEHP(200 mg L^(-1)) in the liquid culture,and more than 55%of DEHP(1.0 g kg^(-1)) in the artificially contaminated soil was removed within 21 d.Furthermore,Rhodococcus sp.strain WJ4 had a strong ability to degrade DEHP without additional nutrients in liquid minimal medium culture and DEHP-contaminated soil and to degrade the homologue of DEHP in both liquid culture and soil.Strain WJ4 represents a novel tool for removing PAEs from contaminated soils and it may have great potential for application in the remediation of environmental pollution by PAEs.展开更多
Chlorobenzenes(CBs) are a group of organic pollutants that pose a high environmental risk due to their toxicity, persistence and possible transfer in the food chain. Available data in literature show that CBs are dete...Chlorobenzenes(CBs) are a group of organic pollutants that pose a high environmental risk due to their toxicity, persistence and possible transfer in the food chain. Available data in literature show that CBs are detected in different environmental compartments such as soil, water, air and sediment. The widespread presence of CBs in the environment is related to their former extensive use in agriculture and industry. Some CBs are ranked in the list of priority pollutants by the Stockholm Convention, and their reduction or elimination from the environment is therefore of high importance. Environmental risk assessment of CBs requires knowledge on the role and importance of the main environmental fate processes, especially in soil. Furthermore, development of remediation strategies for reduction or elimination of CBs from the environment is related to the enhancement of fate processes that increase their dissipation in various environmental compartments. The main objectives of the current review were to present up-to-date data on fate processes of CBs in the soil environment and to explore possible remediation strategies for soils contaminated with CBs.Dechlorination of highly-chlorinated benzenes is the main degradation pathway under anaerobic conditions, leading to the formation of lower-chlorinated benzenes. Biodegradation of lower-chlorinated benzenes is well documented, especially by strains of adapted or specialized microorganisms. Development of techniques that combine dechlorination of highly-chlorinated benzenes with biodegradation or biomineralization of lower-chlorinated benzenes can result in useful tools for remediation of soils contaminated with CBs. In addition,immobilization of CBs in soil by use of different amendments is a useful method for reducing the environmental risk of CBs.展开更多
As one of the most widely distributed bacterial predators in the soil, the role of bacterivorous nematodes on the enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soils is crucial, but remains t...As one of the most widely distributed bacterial predators in the soil, the role of bacterivorous nematodes on the enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soils is crucial, but remains to be investigated.A microcosm-level study was conducted to examine the effects of bacterial-feeding nematode grazing and tea saponin(TS) addition on bioremediation of a pyrene-contaminated soil enhanced by the polycyclic aromatic hydrocarbon(PAH)-degrading bacterial strain Sphingobium sp.PHE9.After 180 d of incubation, the highest pyrene dissipation(71.3%) was achieved through a combination of Sphingobium sp.PHE9 inoculation with nematode and TS addition.Meanwhile, high counts of culturable PAH-degrading bacteria, soil enzyme activity, and biodiversity indices were observed under the combined treatment, implying that the microbiological function of the contaminated soil was significantly restored.Additionally, the results of Tenax~ extraction with the first-order three-compartment model indicated that rate-limiting factors varied among treatments.The lack of degrading microorganisms was the main rate-limiting factor for the treatments involving TS/nematode addition, and inadequate bioaccessible pyrene was the vital rate-limiting factor in the treatments involving Sphingobium sp.PHE9 inoculation.The proposed combined clean-up strategy proved to be a promising bioremediation technology for aged pyrene-contaminated soils.展开更多
Sequential and single extraction procedures were applied to both fresh and dried Sedum Plumbizincicola leaves and stems.The extractants, different from those of soil, sediment or sewage sludge metal fractions, were wa...Sequential and single extraction procedures were applied to both fresh and dried Sedum Plumbizincicola leaves and stems.The extractants, different from those of soil, sediment or sewage sludge metal fractions, were water, 80%(v/v) ethanol, 1 mol/L Na Cl,2% HAc and 0.6 mol/L HCl. Zn, Cd and Cu in the extracts and samples were measured by flame atomic adsorption spectrometry. In sequential extraction procedures, water soluble form and ethanol soluble form are the main fractions for Zn, while water soluble form and Na Cl soluble form for Cd, and comparatively uniform distribution for Cu with the residue form most and HCl soluble form second. Single extraction procedures are used to compare the extraction efficiencies of the five reagents to screen appropriate extractants and operating conditions for liquid extraction to deal with large amount of harvested metal-contained biomass, which will pose a threat to the environment if treated improperly. The sequences of extraction efficiencies are HCl>Na Cl≈HAc>Water≈Ethanol for Zn and HCl≈Na Cl≈HAc>Water>Ethanol for Cd. As for Cu, all the five extractants cannot effectively extract Cu, but HCl achieves a higher efficiency(>70% in fresh samples, and 45%-60% in dried samples). Besides, extraction efficiencies for most extractants in fresh samples are higher than those in dried samples, and extraction efficiencies of stems and leaves for the five extractants are close. The two extraction procedures can obtain high degree of accuracy with the relative standard deviation(RSD)lower than 10%, and metal recoveries are controlled between 80%-120% with most of 90%-110%.展开更多
This study explored the effects of cold plasma treatment on seed germination, plant growth, and peanut yield. Cold plasma treatment improved germination and seedling growth,and the 120 W treatment produced the best ef...This study explored the effects of cold plasma treatment on seed germination, plant growth, and peanut yield. Cold plasma treatment improved germination and seedling growth,and the 120 W treatment produced the best effect. Germination potential and germination rate were markedly raised by 150% and 21%, respectively. Germination was accelerated and the uniformity of emergence improved. The apparent contact angle was decreased by 53%. Seedling shoot and root dry weights increased by 11% and 9%. Leaf area, leaf thickness, leaf nitrogen concentration, chlorophyll contents, and dry weight at the fruiting stage, together with plant height, stem diameter, and root dry weight at the mature stage were all markedly raised by the cold plasma treatment. The cold plasma treatment enhanced yield components, such as branch numbers per plant, pod numbers per plant, and 100 pod weights by 8%, 13%, and 9%, respectively,compared to the control. Furthermore, the yield improved by 10%. These results suggested that cold plasma treatment improved germination, plant growth, and yield, which might be due to the cold plasma increasing the leaf area, nitrogen concentrations, and chlorophyll contents.展开更多
A chlorothalonil(CTN)-degrading bacterial strain H4 was isolated in this study from a contaminated soil by continuous enrichment culture to identify its characteristics and to investigate its potential for remediation...A chlorothalonil(CTN)-degrading bacterial strain H4 was isolated in this study from a contaminated soil by continuous enrichment culture to identify its characteristics and to investigate its potential for remediation of CTN in contaminated soil. Based on the morphological, physiological and biochemical tests and 16 S r DNA sequence analysis, the strain was identified as Stenotrophomonas sp. After liquid culture for 7 d, 82.2% of CTN was removed by strain H4. The isolate could degrade CTN over a broad range of temperatures and p H values, and the optimum conditions for H4 degradation were p H 7.0 and 30℃. Reintroduction of the bacteria into artificially contaminated soil resulted in substantial removal of CTN(> 50%) after incubation for 14 d. Soil samples treated by H4 showed significant increases(P < 0.05) in soil dehydrogenase activity, soil polyphenol oxidase activity, average well-color development obtained by the Biolog Eco plate TM assay and Shannon-Weaver index, compared with the control. Strain H4 might be a promising candidate for application in the bioremediation of CTN-contaminated soils.展开更多
Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conv...Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conversion.However,high-performance TiO_(2)-based electrocatalysts for HER are quite limited,and the cat alytic active centers still remain elusive.Herein,a simple strategy is demonstrated for the synthesis of TiO_(2)-carbon composite(TiO_(2)/C)with high HER performance and stability.The remarkable HER performance of TiO_(2)/C can be ascribed to the doping of carbon atoms,which leads to stronger hybridization of Ti 3d and O 2p orbitals,thus substantially improving the electrocatalytic efficiency.This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electro catalysts with high catalytic activity and stability at high current density for HER.展开更多
pHKCl and pHH2O are two basic necessary indexes to reflect the acidity of asoil. Predicting pHKCl?directly from pHH2O?could save the cost of laboratory work. In this study, the values of pHKCl and of 442 and 310 horiz...pHKCl and pHH2O are two basic necessary indexes to reflect the acidity of asoil. Predicting pHKCl?directly from pHH2O?could save the cost of laboratory work. In this study, the values of pHKCl and of 442 and 310 horizon samples from 126 and 98 soil profiles (0 - 120 cm in depth) surveyed from 2014 to 2015 in Guangxi and Yunnan were used to establish the optimal correlation model between pHKCl and pHH2O. The results showed that: 1) pHKCl is lower than pHH2O, pHKCl?was 0.07 - 1.99 units with a mean of 0.99 units lower than for Guangxi, while 0.03 - 1.90 units with a mean of 0.89 lower than pHH2O?for Yunan. 2) There is significant positive correlation between pHKCl?and pHH2O, the optimal correlation models between pHKCl?(y) and pHH2O?(x) for Guangxi and Yunnan are y = 0.1963x2 −1.0512x + 4.338, R2 = 0.836, p 0.1859x, R2 = 0.769, p pHKCl?with exchangeable H+ and Al3+ (R2 = 0.487, 0.716, p pHKCl?is dominated by exchangeable Al3+, followed by exchangeable H+, and their contribution to pHKCl?were 71.1% and 28.7%, respectively.展开更多
基金Project supported by the National Science & Technology Pillar Program of China during the Eleventh Five-Year Plan Period (No. 2008BADA7B02)the National Natural Science Foundation of China (No. 40773075)the Natural Science Foundation of Jiangsu Province,China (No. BK2007262)
文摘Excess phosphorus (P) from agricultural soils contributes to eutrophication in water bodies.Samples (n=60) were taken from sites where rice paddies have been converted to vegetable fields for 0,< 10,10-20,and > 20 years and analyzed for five inorganic P (Pi) fractions,three organic P(Po) fractions,and several soil parameters to investigate how land use conversion affects Pi and Po fractions in a peri-urban area of China with soils characteristic of many agricultural areas of Asia.Significant increases of 33,281,293,and 438 mg kg 1 were found for soluble and loosely bound Pi (SL-Pi),aluminum-bound Pi (Al-Pi),calcium-bound P i (Ca-Pi),and iron-bound Pi (Fe-Pi),respectively,after conversion from rice paddies to vegetable fields.Most of the increase in Pi was in the form of Fe-Pi,which increased from 8% of total P (TP) on paddy soil to 31% on the soil with > 20-year vegetable cultivation,followed by Al-Pi,which increased from 2% to 19% of TP.For Po fractions,there was no significant change in P concentrations.The conversion of land use from paddy fields to high intensity vegetable fields was causing significant changes in soil P fractions.Management practices were causing a buildup of soil P,primarily in the Fe-Pi fraction,followed by Ca-Pi and Al-Pi fractions.If current trends continue,a 30%-70% increase in TP could be expected in the next 20 years.Farmers in the area should reduce P application and use to maximize P uptake.
基金Project supported by the National Key Basic Research Program (973 Program) of China (No. 2007CB106804)the PhD candidate Training Program (No. 20060730027)+1 种基金the "111" Project from the State Administration of Foreign Experts Affairs (SAFEA)the Ministry of Education of China
文摘To show the vegetation succession interaction with soil properties, microbial biomass, basal respiration, and enzyme activities in different soil layers (0-60 cm) were determined in six lands, i.e., 2-, 7-, 11-, 20-, and 43-year-old abandoned lands and one native grassland, in a semiarid hilly area of the Loess Plateau. The results indicated that the successional time and soil depths affected soil microbiological parameters significantly. In 20-cm soil layer, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), MBC/MBN, MBC to soil organic carbon ratio (MBC/SOC), and soil basal respiration tended to increase with successional stages but decrease with soil depths. In contrast, metabolic quotient (qCO 2 ) tended to decrease with successional stages but increase with soil depths. In addition, the activities of urease, catalase, neutral phosphatase, β-fructofuranosidase, and carboxymethyl cellulose (CMC) enzyme increased with successional stages and soil depths. They were significantly positively correlated with microbial biomass and SOC (P < 0.5), whereas no obvious trend was observed for the polyphenoloxidase activity. The results indicated that natural vegetation succession could improve soil quality and promote ecosystem restoration, but it needed a long time under local climate conditions.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.ISSASIP 0718)the National Natural Science Foundation of China (Nos.40401030 and 40871114)
文摘To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions,and to evaluate the mean Gibbs free binding and adsorption energies of various cations on particles of red soil and latosol,clay fractions smaller than 2 μm were separated from samples of the two variable-charge soils.Ferric oxides were removed from part of the clay fractions,which were then saturated with various chlorides(NaCl,KCl,CaCl2,CdCl2 or LaCl3).Electrical conductivities(EC) of dilute suspensions of the original and of the iron oxides-free clay fractions in deionized water were measured with the SHP-2 short high-voltage pulse apparatus,which enables measurement of the Wien effect at field strengths(E) from 14 to 250 kV cm-1.The Wien effect(EC-E) curves revealed EC increases of red soil suspensions between 14 and 200 kV cm-1,of 8.3,8.4,12.1,5.9,and 1.2 μS cm-1 for NaCl,KCl,CaCl2,CdCl2,and LaCl3,respectively,reflecting the differing interactions with the various cations and chloride.The EC increments with the iron-free red soil suspensions were higher,being 29.7,17.2,and 15.3 μS cm-1 for NaCl,CaCl2,and CdCl2,respectively.In the natural latosol suspensions the EC increments were practically zero,whereas in the iron-free fractions there were significant EC increments of 10.3,5.7,5.0,and 1.6 μS cm-1 for NaCl,CaCl2,CdCl2,and LaCl3,respectively.
基金funded by the "973" Program of China (2007CB407206)the ISSCAS Innovation Program (ISSASIP0602)the Knowledge Innovation Project of the Chinese Academy of Sciences (KZCX2-YW-438)
文摘This paper reports the dynamic changes of soil and water loss in the red soil region of Southern China since the 1950s. The red soil region covers eight provinces: Jiangxi, Zhejiang, Fujian, Anhui, Hubei, Hunan, Guangdong and Hainan. From the 1950s to 1986, the annual rate of soil erosion increased by 3.4%. From 1986 to 1996 and from 1996 to 2000, the annual rates of soil erosion decreased by 2.0% and 0.32%, respectively. Field surveys showed that from 2000 to 2005, the area of soil and water loss decreased annually by 1.2%. This decrease was a result of large-scale erosion control activities across China. Although the eroded soil has been restored, the restoration process is very slow and full restoration will take a long time. Our report suggests that controlling soil and water loss is a challenging task, and additional measures must be taken to effectively control the soil erosion in the red soil region.
基金supported by Jiangsu Province Science and Technology Support Program of China(No.BE2013452)Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences(No.KSCX-EW-B-6)
文摘This study investigated the e?ect of cold helium plasma treatment on seed germination, growth and yield of wheat. The e?ects of di?erent power of cold plasma on the germination of treated wheat seeds were studied. We found that the treatment of 80 W could significantly improve seed germination potential(6.0%) and germination rate(6.7%) compared to the control group. Field experiments were carried out for wheat seeds treated with 80 W cold plasma. Compared with the control, plant height(20.3%), root length(9.0%) and fresh weight(21.8%) were improved significantly at seedling stage. At booting stage, plant height, root length, fresh weight, stem diameter, leaf area and leaf thickness of the treated plant were respectively increased by 21.8%, 11.0%, 7.0%, 9.0%, 13.0% and 25.5%. At the same time, the chlorophyll content(9.8%), nitrogen(10.0%) and moisture content(10.0%) were higher than those of the control, indicating that cold plasma treatment could promote the growth of wheat. The yield of treated wheat was 7.55 t · ha-1, 5.89% more than that of the control. Therefore, our results show that cold plasma has important application prospects for increasing wheat yield.
基金supported by the National Key Research and Development Program of China(Nos.2016YFD0200305,2017YFD0200604)the Knowledge Innovation Program of the Institute of Soil Science,the Chinese Academy of Sciences(No.ISSASIP1634)+2 种基金the Jiangsu Provincial Public Institutions Program for Research Conditions and Building Capacity(No.BM2015019)the Foundation of Jiangsu Key Laboratory for the Research and Utilization of Plant Resources(No.JSPKLB201606)the Suzhou Xiangcheng District Science and Technology Project(No.201703)
文摘The effects of low-vacuum helium cold plasma treatment on the seed germination,plant growth and yield of oilseed rape(Brassica napus L.cv.Zhongshuang 9) were investigated.Seeds were exposed to low-vacuum helium cold plasma ranging from 0–120 W for 15 s.Cold plasma increased the germination,plant growth and yield of oilseed rape,and the treatment of 100 W provided the best result.The germination rate,germination and vigor indices,and uniformity of emergence were improved by cold plasma treatment.Cold plasma raised the relative conductivity and water uptake,and reduced the apparent contact angle.The characteristics of plant growth,including plant height,stem diameter,dry weights of shoot and root at the seedling,bolting and flowering stages were increased by the cold plasma treatment.Yield components,including pod numbers per plant and 1000 seed weights were increased by the cold plasma treatment.Furthermore,the yield per plant increased by 28.20%.These results suggest that cold plasma treatment has the potential to improve the yield of oilseed rape through the enhancement of permeability,wettability and capacity of water uptake of the seeds,seed germination and plant growth.
基金the National Natural Science Foundations of China(41877528,41471432 and 31500977)。
文摘Brassica napus L.(B.napus)is an important oil crop worldwide and it rapidly accumulates oil at late stage of seed maturation.However,little is known about the cellular mechanism of oil accumulation and seed color changes during the late stage of rapeseed development.Here,we analyzed the ultrastructure of seed coat,aleurone and cotyledon in embryos of B.napus from 25 to 70 days after flowering(DAF).The pigments,which were deposited on the cell wall of palisade cells in seed coat,determined dark black color of rapeseed.The chloroplasts degenerated into non-photosynthetic plastids which caused the green cotyledon to turn into yellow.The chloroplasts in aleurone and cotyledon cells respectively degenerated into remnants without inner and outer envelope membranes and ecoplasts with intact inner and outer envelope membranes.From 40 to 70 DAF,there were degraded chloroplasts without thylakoid,oil bodies contacting with plastids or protein bodies,big starch deposits of chloroplasts degrading into small particles then disappearing,and small endoplasmic reticulum(ER)in aleurone and cotyledon cells.Additionally,there were decreases of chlorophyll content and dramatic increases of oil content in rapeseed.These results suggested that the rapid oil accumulation was independent on the NADPH synthesized by photosynthesis of chloroplasts and probably utilized other sources of reductant,such as the oxidative pentose phosphate pathway during the late stage of rapeseed development.The triacylglycerol assembly presumably utilizes the enzymes in the plastid,cytosol or oil body of cotyledon and aleurone cells.
文摘The global soil environment has been under increasing pressure due to rapid industrialization and urbanization,along with intensive farming on arable land.In particular,the soil environmental quality in China is deteriorating in a rapid pace according to the'National Soil Pollution Survey'by the Ministry of Environmental Protection and the Ministry of Land and Resources of China(released on April 17,2014).
基金financially supported by the National Key Research and Development Program of China (No. 2018YFC1803100)the Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2018350)。
文摘The biosurfactants rhamnolipids and the “soil ecosystem engineers” earthworms are often used to remediate contaminated soils. However, the effects of rhamnolipids on earthworm intestinal flora and microbial community in soil containing earthworms are not clearly understood. In our study, a 21-d microcosm experiment was carried out to reveal the effects of rhamnolipids on microbial abundance, composition, and metabolism, as well as contaminant degradation capacity. Both rhamnolipids and earthworms had positive effects on soil bacteria. Rhamnolipid-amended soil(RT) showed higher bacterial abundance and metabolic activity than earthworm-amended soil(ET), while the improvement in bacterial composition and contaminant degradation capacity by rhamnolipids was lower than that by earthworms. Notably, these effects were further amplified by the combined treatment of rhamnolipids and earthworms(RET). Specifically, the bacterial abundance(log-transferred) increased from 9.5 copies g-1in the control with no addition to 10.3, 10.6, and 11.1 copies g-1in ET, RT, and RET, respectively. Compared to ET, the relative abundance of the dominant phylum, Proteobacteria, increased from 41.66% to 51.67% in RET,and more pollutant-degrading bacteria were also enriched in RET. Therefore, the increases in bacterial abundance and contaminant-degrading bacteria led to the following ranking of soil dioxin removal rate: RET(77.28%) > ET(59.83%) > RT(24.65%) > control(4.71%). Moreover, the addition of rhamnolipids enhanced the abundance of bacterial functional genes involved in metabolism and environmental information processing. In addition, the composition and diversity of bacteria in the gut of earthworms were conspicuously affected by rhamnolipids, and the relative abundance of Microbacterium and Shewanella increased significantly(P < 0.05). Therefore, this study revealed that rhamnolipids remarkably influenced the abundance, composition, and metabolism of the microbial community in earthworm gut, further promoting the degradation rate of dioxin, providing theoretical support for optimizing the combined application of rhamnolipids and earthworms in soil bioremediation engineering and for the assessment of the ecological impact of rhamnolipids.
基金supported by the Provincial Natural Science Foundation of Hunan, China (No. 2020JJ4429)the Open Fund of the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau of China (No. A314021402-202101)the Hundred-Talent Project of Chinese Academy of Sciences (No. A315021407).
文摘With global climate change, soil drying-rewetting(DRW) events have intensified and occurred frequently on the Loess Plateau of China. However, the extent to which the DRW cycles with different wetting intensities and cycle numbers alter microbial community and respiration is barely understood. Here,indoor DRW one and four cycles treatments were implemented on soil samples obtained from the Loess Plateau, involving increase of soil moisture from10% water-holding capacity(WHC) to 60% and 90% WHC(i.e., 10%–60% and 10%–90% WHC, respectively). Constant soil moistures of 10%, 60%,and 90% WHC were used as the controls. The results showed that bacterial diversity and richness decreased and those of fungi remained unchanged under DRW treatments compared to the controls. Under all moisture levels, Actinobacteriota and Ascomycota were the most dominant bacterial and fungal phyla,respectively. The bacterial network was more complex than that of fungi, indicating that bacteria had a greater potential for interaction and niche sharing under DRW treatments. The pulse of respiration rate declined as the DRW cycle increased under 10%–60% WHC, but remained similar for different cycles under 10%–90% WHC. Moreover, the DRW treatments reduced the overall carbon loss, and the direct carbon release under 10%–60% WHC was larger than that under 10%–90% WHC. The cumulative CO_(2) emissions after four DRW cycles were significantly positively correlated with microbial biomass carbon and negatively correlated with fungal richness(Chao 1).
基金the Financial of National Key Research and Development Project of China(No.2019YFC1805102)Partial supports are from the National Natural Science Foundation of China(Nos.42107228 and 41977266)Shanghai Pujiang Program(No.21PJ1401000)。
文摘Ion-absorbed rare earth mines,leached in situ,retain a large amount of ammonium nitrogen(NH4–N)that continuously releases into the surrounding environments.However,quantitative descriptions and predictions of the transport of NH4–N across mining area with hill slopes are not fully established.Here,laboratory column experiments were designed with an inclined slope(a sand box)to examine the spatial temporal transport of NH4–N in soils collected from the ionic rare earth elements(REE)mining area.An HYDRUS-2D model simulation of the experimental data over time showed that soils had a strong adsorption capacity toward NH4–N.Chemical non-equilibrium model(CNEM)could well simulate the transport of NH4–N through the soil-packed columns.The simulation of the transport-adsorption processes at three flow rates of leaching agents revealed that low flow rate enabled a longer residence time and an increased NH4-N adsorption,but reduced the extraction efficiency for REE.During the subsequent rainwater washing process,the presence of slope resulted in the leaching of NH4–N on the surface of the slope,while the leaching of NH4–N deep inside the column was inhibited.Furthermore,the high-intensity rainfall significantly increased the leaching,highlighting the importance of considering the impact of extreme weather conditions during the leaching process.Overall,our study advances the understanding of the transport of NH4–N in mining area with hills,the impact of flow rates of leaching agents and precipitation intensities,and presents as a feasible modeling method to evaluate the environmental risks of NH4–N pollution during and post REE in situ mining activities.
基金financially supported by the Hundred-talent Project of the Chinese Academy of Sciences(A315021407).
文摘Altered drying-rewetting(DRW)procedures due to climate change may influence soil microbial properties and microbially-mediated carbon cycling in arid and semi-arid regions.However,the effects of DRW of different intensities on the microbial properties and respiration are not well understood.Thus,the responsive patterns of microbial communities and carbon mineralization in agriculture soil on the Chinese Loess Plateau to DRW treatments with different wetting intensities(5%-25% and 5%-36%)and frequency(1-cycle to 4-cycle)were investigated.Continuous moisture levels of 5%,25% and 36% were used as control.Results revealed that the reduction of bacterial diversity and richness were greater for 5%-36% than 5%-25% treatment,while diversity of fungi was similar for different wetting intensities.Bacterial communities became clustered by wetting intensity rather than cycle number,however fungal community was unaffected by DRW.The complexity of bacterial co-occurrence network increased because of higher nodes,edges,average degree,diameter and average cluster coefficient after 4-cycles,and the interaction was more complex after 1-cycle for fungi.Rewetting caused a pulse-like increase of respiration rate,and the pulse amplitude was greater for DRW with high rewetting intensity and decreased with the increase of cycle number.The cumulative CO_(2) emission for DRW treatments was lower than that for the continuous moisture conditions.The net reduction of carbon release for 5%-36% treatment was 1.18 times higher than that for 5%-25% treatment.Our study provides experimental evidence of the positive potential of DRW processes for maintaining soil carbon stock in an agriculture system on the Loess Plateau.
基金supported by the National Environmental Protection Special Funds for Scientific Research on Public Causes in China(Nos.201109018 and 2010467016)Jiangsu Provincial Postdoctoral Fund of China(No.1202050C)
文摘Di-(2-ethylhexyl) phthalate(DEHP) is a high-molecular-weight phthalate ester(PAE) that has been widely used in the manufacture of polyvinylchloride and contributes to environmental pollution.The objectives of the present study were to isolate a DEHP degrader that can utilize DEHP as a carbon source and to investigate its capacity to biodegrade DEHP in both liquid culture and soil.A bacterial strain WJ4 was isolated from an intensively managed vegetable soil,which was contaminated with PAEs.The strain WJ4 was affiliated to the genus Rhodococcus and was able to remove DEHP from soil effectively.A period of only 7 d was required to degrade about 96.4%of DEHP(200 mg L^(-1)) in the liquid culture,and more than 55%of DEHP(1.0 g kg^(-1)) in the artificially contaminated soil was removed within 21 d.Furthermore,Rhodococcus sp.strain WJ4 had a strong ability to degrade DEHP without additional nutrients in liquid minimal medium culture and DEHP-contaminated soil and to degrade the homologue of DEHP in both liquid culture and soil.Strain WJ4 represents a novel tool for removing PAEs from contaminated soils and it may have great potential for application in the remediation of environmental pollution by PAEs.
基金financially supported by the Outstanding Youth Fund of the Natural Science Foundation of Jiangsu, China (No. BK20150050)the National Science and Technology Major Project of China (No. 2016YFD08000204)+2 种基金the National Key Basic Research Program of China (No. 2014CB441105)the National Natural Science Foundation of China (Nos. 21277148, 21677149 and 41671236)the National Council for Science and Technology of Kenya (No. NCST/ST&I/RCD/2ND CALL/POST DOC/039)
文摘Chlorobenzenes(CBs) are a group of organic pollutants that pose a high environmental risk due to their toxicity, persistence and possible transfer in the food chain. Available data in literature show that CBs are detected in different environmental compartments such as soil, water, air and sediment. The widespread presence of CBs in the environment is related to their former extensive use in agriculture and industry. Some CBs are ranked in the list of priority pollutants by the Stockholm Convention, and their reduction or elimination from the environment is therefore of high importance. Environmental risk assessment of CBs requires knowledge on the role and importance of the main environmental fate processes, especially in soil. Furthermore, development of remediation strategies for reduction or elimination of CBs from the environment is related to the enhancement of fate processes that increase their dissipation in various environmental compartments. The main objectives of the current review were to present up-to-date data on fate processes of CBs in the soil environment and to explore possible remediation strategies for soils contaminated with CBs.Dechlorination of highly-chlorinated benzenes is the main degradation pathway under anaerobic conditions, leading to the formation of lower-chlorinated benzenes. Biodegradation of lower-chlorinated benzenes is well documented, especially by strains of adapted or specialized microorganisms. Development of techniques that combine dechlorination of highly-chlorinated benzenes with biodegradation or biomineralization of lower-chlorinated benzenes can result in useful tools for remediation of soils contaminated with CBs. In addition,immobilization of CBs in soil by use of different amendments is a useful method for reducing the environmental risk of CBs.
基金financially supported by the National Natural Science Foundation of China(Nos.41371263 and 41771350)the Fundamental Research Funds for the Central Universities of China(Nos.KYTZ201404 and Y0201700160)+3 种基金the Agricultural Science and Technology Innovation Fund of Jiangsu Province,China(No.CX(17)3047)the Agro-scientific Research in the Public Interest of China(No.201503121)the Environmental Protection Research Project in Jiangsu Province,China(No.2017005)the National Key Research and Development Program of China(Nos.2016YFD0200106 and 2016YFD0300908)
文摘As one of the most widely distributed bacterial predators in the soil, the role of bacterivorous nematodes on the enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soils is crucial, but remains to be investigated.A microcosm-level study was conducted to examine the effects of bacterial-feeding nematode grazing and tea saponin(TS) addition on bioremediation of a pyrene-contaminated soil enhanced by the polycyclic aromatic hydrocarbon(PAH)-degrading bacterial strain Sphingobium sp.PHE9.After 180 d of incubation, the highest pyrene dissipation(71.3%) was achieved through a combination of Sphingobium sp.PHE9 inoculation with nematode and TS addition.Meanwhile, high counts of culturable PAH-degrading bacteria, soil enzyme activity, and biodiversity indices were observed under the combined treatment, implying that the microbiological function of the contaminated soil was significantly restored.Additionally, the results of Tenax~ extraction with the first-order three-compartment model indicated that rate-limiting factors varied among treatments.The lack of degrading microorganisms was the main rate-limiting factor for the treatments involving TS/nematode addition, and inadequate bioaccessible pyrene was the vital rate-limiting factor in the treatments involving Sphingobium sp.PHE9 inoculation.The proposed combined clean-up strategy proved to be a promising bioremediation technology for aged pyrene-contaminated soils.
基金Project(2013CB228106)supported by the National Key Basic Research Program of ChinaProject(2012AA06A204)supported by the National High Technology Research and Development Program of China
文摘Sequential and single extraction procedures were applied to both fresh and dried Sedum Plumbizincicola leaves and stems.The extractants, different from those of soil, sediment or sewage sludge metal fractions, were water, 80%(v/v) ethanol, 1 mol/L Na Cl,2% HAc and 0.6 mol/L HCl. Zn, Cd and Cu in the extracts and samples were measured by flame atomic adsorption spectrometry. In sequential extraction procedures, water soluble form and ethanol soluble form are the main fractions for Zn, while water soluble form and Na Cl soluble form for Cd, and comparatively uniform distribution for Cu with the residue form most and HCl soluble form second. Single extraction procedures are used to compare the extraction efficiencies of the five reagents to screen appropriate extractants and operating conditions for liquid extraction to deal with large amount of harvested metal-contained biomass, which will pose a threat to the environment if treated improperly. The sequences of extraction efficiencies are HCl>Na Cl≈HAc>Water≈Ethanol for Zn and HCl≈Na Cl≈HAc>Water>Ethanol for Cd. As for Cu, all the five extractants cannot effectively extract Cu, but HCl achieves a higher efficiency(>70% in fresh samples, and 45%-60% in dried samples). Besides, extraction efficiencies for most extractants in fresh samples are higher than those in dried samples, and extraction efficiencies of stems and leaves for the five extractants are close. The two extraction procedures can obtain high degree of accuracy with the relative standard deviation(RSD)lower than 10%, and metal recoveries are controlled between 80%-120% with most of 90%-110%.
基金supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of China(No.2012BAD05B04)National Natural Science Foundation of China(No.41201241)+1 种基金“Strategic Priority Research Program”of the Chinese Academy of Sciences(No.XDB15030301)Jiangsu Province Science and Technology Support Program(No.BE2013452)
文摘This study explored the effects of cold plasma treatment on seed germination, plant growth, and peanut yield. Cold plasma treatment improved germination and seedling growth,and the 120 W treatment produced the best effect. Germination potential and germination rate were markedly raised by 150% and 21%, respectively. Germination was accelerated and the uniformity of emergence improved. The apparent contact angle was decreased by 53%. Seedling shoot and root dry weights increased by 11% and 9%. Leaf area, leaf thickness, leaf nitrogen concentration, chlorophyll contents, and dry weight at the fruiting stage, together with plant height, stem diameter, and root dry weight at the mature stage were all markedly raised by the cold plasma treatment. The cold plasma treatment enhanced yield components, such as branch numbers per plant, pod numbers per plant, and 100 pod weights by 8%, 13%, and 9%, respectively,compared to the control. Furthermore, the yield improved by 10%. These results suggested that cold plasma treatment improved germination, plant growth, and yield, which might be due to the cold plasma increasing the leaf area, nitrogen concentrations, and chlorophyll contents.
基金Supported by the Public Service Special Project of the Environmental Protection Ministry of China(No.201109018)
文摘A chlorothalonil(CTN)-degrading bacterial strain H4 was isolated in this study from a contaminated soil by continuous enrichment culture to identify its characteristics and to investigate its potential for remediation of CTN in contaminated soil. Based on the morphological, physiological and biochemical tests and 16 S r DNA sequence analysis, the strain was identified as Stenotrophomonas sp. After liquid culture for 7 d, 82.2% of CTN was removed by strain H4. The isolate could degrade CTN over a broad range of temperatures and p H values, and the optimum conditions for H4 degradation were p H 7.0 and 30℃. Reintroduction of the bacteria into artificially contaminated soil resulted in substantial removal of CTN(> 50%) after incubation for 14 d. Soil samples treated by H4 showed significant increases(P < 0.05) in soil dehydrogenase activity, soil polyphenol oxidase activity, average well-color development obtained by the Biolog Eco plate TM assay and Shannon-Weaver index, compared with the control. Strain H4 might be a promising candidate for application in the bioremediation of CTN-contaminated soils.
基金supported bythe Natural Scientific Foundation of China(Grants 21878001,22078002,21776001,21875001,21978002,21808002,22008001,and U1710114).
文摘Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conversion.However,high-performance TiO_(2)-based electrocatalysts for HER are quite limited,and the cat alytic active centers still remain elusive.Herein,a simple strategy is demonstrated for the synthesis of TiO_(2)-carbon composite(TiO_(2)/C)with high HER performance and stability.The remarkable HER performance of TiO_(2)/C can be ascribed to the doping of carbon atoms,which leads to stronger hybridization of Ti 3d and O 2p orbitals,thus substantially improving the electrocatalytic efficiency.This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electro catalysts with high catalytic activity and stability at high current density for HER.
文摘pHKCl and pHH2O are two basic necessary indexes to reflect the acidity of asoil. Predicting pHKCl?directly from pHH2O?could save the cost of laboratory work. In this study, the values of pHKCl and of 442 and 310 horizon samples from 126 and 98 soil profiles (0 - 120 cm in depth) surveyed from 2014 to 2015 in Guangxi and Yunnan were used to establish the optimal correlation model between pHKCl and pHH2O. The results showed that: 1) pHKCl is lower than pHH2O, pHKCl?was 0.07 - 1.99 units with a mean of 0.99 units lower than for Guangxi, while 0.03 - 1.90 units with a mean of 0.89 lower than pHH2O?for Yunan. 2) There is significant positive correlation between pHKCl?and pHH2O, the optimal correlation models between pHKCl?(y) and pHH2O?(x) for Guangxi and Yunnan are y = 0.1963x2 −1.0512x + 4.338, R2 = 0.836, p 0.1859x, R2 = 0.769, p pHKCl?with exchangeable H+ and Al3+ (R2 = 0.487, 0.716, p pHKCl?is dominated by exchangeable Al3+, followed by exchangeable H+, and their contribution to pHKCl?were 71.1% and 28.7%, respectively.
