The addition of silicon(Si)and organic fertilizers to soil conditioners can inhibit the transfer of heavy metal ions from soil to crops.However,it is not clear how Si and organic fertilizers affect soil properties and...The addition of silicon(Si)and organic fertilizers to soil conditioners can inhibit the transfer of heavy metal ions from soil to crops.However,it is not clear how Si and organic fertilizers affect soil properties and the micro-ecological environment and thereby reduce cadmium(Cd)accumulation in rice.In this study,the effects of L-type soil conditioners containing Si and organic fertilizers on bacterial and fungal community diversity,soil pH,organic matter,and available Si were analyzed with field experiments at two sites in Liuzhou City and Hezhou City,respectively,in Guangxi,China.With the increase of Si and organic fertilizer content in soil conditioner,rice yield respectively increased by 16.8–25.8 and 6.8–13.1%,and rice Cd content decreased significantly by 8.2–21.1 and 10.8–40.6%,respectively,at the two experimental sites.Soil microbiome analysis showed that the increase in abundance of Firmicutes and Actinobacteriota bacteria associated with Cd adsorption and sequestration,and Basidiomycota fungal populations associated with degradation of macromolecules favored the inhibition of soil Cd activity(soil exchangeable Cd decreased by 14.4–14.8 and 18.1–20.6%).This was associated with an increase in organic matter and Si content caused by applying soil conditioners.In conclusion,L-type soil conditioners,rich in Si and organic fertilizer,can reduce soil Cd bioavailability by regulating the dominant Cd passivating flora in the soil and ultimately reduce Cd accumulation in rice.展开更多
High grain-Cd-accumulating rice variety Yongyou 9 was planted in Cd-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid(ALA) and24-epibrassinolide(EBR) on Cd a...High grain-Cd-accumulating rice variety Yongyou 9 was planted in Cd-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid(ALA) and24-epibrassinolide(EBR) on Cd accumulation in brown rice. Results showed that the exogenous ALA and EBR had no significant effects on agronomic traits, soil pH and total Cd content in soil, but had some effects on the available Cd content in soil, and significantly influenced the Cd accumulation in the different parts of rice. Results also showed that 100 mg/L exogenous ALA significantly reduced the Cd accumulation in brown rice to blow the food safety standard(0.2 mg/kg), and also significantly reduced the Cd contents in the roots and culm of rice. However, 200 mg/L exogenous ALA treatment increased the Cd content in brown rice remarkably. In addition, 0.15 mg/L EBR treatment increased Cd accumulation in roots, culm, leaves and brown rice notably, whereas 0.30 mg/L exogenous EBR treatment reduced the Cd accumulation in brown rice properly, but it was not significant. Therefore,proper concentration of ALA can effectively reduce the Cd accumulation in brown rice, which can be used as an effective technical method for the safe production of rice in Cd polluted farmland.展开更多
The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long h...The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long history of numerous wars, foreign occupations, and most recently the Second Indochina War (aka the Vietnam War 1965-1972) which defoliated rain forests and ancient wetland mangroves and left behind contaminated soil and sediment hotspots. During this war, the United States (US) military sprayed 80 million liters of Agent Orange contaminated with the dioxin TCDD in a guerrilla war against communist insurgents. Agent Orange was a synthetic plant growth regulator comprised of equal amounts of two herbicides 2,4-dichloro phenoxyacetic acid C8H6Cl2O3 (2,4-D) and 2,4,5-trichlorophenoxyacetic acid C8H5Cl3O3 (2,4,5-T). TCDD, the dioxin, 2,3,7,8-tetrachlorodibenzodioxin (C12H4Cl4O2) was an unintended byproduct of the accelerated combustion process used in the manufacture of herbicides containing 2,4,5-T. Agent Orange has frequently been blamed for soil and sediment contamination and long-term human health problems;however, the true source of harm is the dioxin TCDD. Agent Orange has a short half-life of days and weeks after application to vegetation, and has not been found to persist, after 50 years, in the water or soils of southern Vietnam. However, the half-life of dioxin TCDD depends on where it is deposited and varies from 1 to 3 years on soil surfaces that have been fully exposed to sunlight, to as long as 20 to 50 years or more when buried in tropical subsoils, and more than 100 years in river and sea sediments. Dioxin TCDD was heavily concentrated in the US Air Force bases in Vietnam where the herbicides were stored, loaded on planes and helicopters for aerial spraying, and used extensively around military base perimeter fences as a security measure to prevent surprise attacks. Bien Hoa Air Force base, 40 km northeast of Ho Chi Minh City, continues to be one of the mega-hotspots where after 48 years the dioxin TCDD levels in fish and shrimp are still high and fishing is banned in ponds and lakes adjacent to the airbase. Although expensive, one of the most effective remediation to dioxin TCDD contaminated soils is incineration which is the recommended method of dioxin TCDD disposal.展开更多
Iron-based amorphous crystalline powder Fe_(78)Si_(9)B_(13)^(AP)is used as a permeability reaction barrier(PRB)combined with an electrokinetic method(EK-PRB)to study the removal rate of Cu in contaminated soil.After t...Iron-based amorphous crystalline powder Fe_(78)Si_(9)B_(13)^(AP)is used as a permeability reaction barrier(PRB)combined with an electrokinetic method(EK-PRB)to study the removal rate of Cu in contaminated soil.After treating Cucontaminated soil for 5 days under different voltage gradients and soil water content,the soil pH is between 3.1 and 7.2.The increase of voltage gradient and soil water content can effectively promote the movement of Cu^(2+) to the cathode.The voltage gradient is 3 V/cm,and the water content of 40%is considered to be an optional experimental condition.Therefore,under this condition,the effects of Fe_(78)Si_(9)B_(13)^(AP)and zero-valent iron(ZVI)as PRB on the removal rate of total Cu in soil and the transformation of chemical forms of Cu are studied.Compared with ZVI,Fe_(78)Si_(9)B_(13)^(AP)as PRB has a better remediation effect.EK-Fe_(78)Si_(9)B_(13)^(AP)can remove 80.3%of total Cu in soil,and the biologically available Cu is reduced to 3.6%,which effectively reduces the environmental risk of contaminated soil.展开更多
Statistical comparison of two remediation methods: Remedial nutrient solution and enhanced natural attenuation were analyzed in terms of TPH of different soil samples collected from Khana Local Government Area of Rive...Statistical comparison of two remediation methods: Remedial nutrient solution and enhanced natural attenuation were analyzed in terms of TPH of different soil samples collected from Khana Local Government Area of Rivers State, Nigeria at different locations and placed inside sample bottles labelled A to D and replicated into two, one for each of the above treatment technique. The TPH of the soil was determined using GC analyzer after solvent extraction was carried out using hexane/dichloromethane mixture. Three batches of treatment were performed on the samples at every interval of eight weeks for a duration of six months. The result obtained was analyzed using a two-way ANOVA factorial experimental design to test the significance of the various sources of variation. From the result obtained, source of variation for sample and interactions were non-significantly different from each other which means that irrespective of the number of samples analyzed or the combination of both samples and batches of treatment, they will still not be significantly different from each other. The source of variation for batch and replications were significantly different from each other and this means that irrespective of the batches of treatment applied or the number of replications (methods of treatment used), they will always be significantly different from each other. The individual comparison of each sample showed that the efficiency of the Remedial Nutrient Solution method was better than Enhanced Natural Attenuation method.展开更多
为遴选可有效表征农田土壤Cd生物有效性的指标,文章采集浙江某地20组稻米及其协同土壤,分析稻米Cd质量比、土壤的基本理化性质、Cd总质量比、不同浸提态Cd质量比及欧共体标准物质局(European Community Bureau of Reference,BCR)形态。...为遴选可有效表征农田土壤Cd生物有效性的指标,文章采集浙江某地20组稻米及其协同土壤,分析稻米Cd质量比、土壤的基本理化性质、Cd总质量比、不同浸提态Cd质量比及欧共体标准物质局(European Community Bureau of Reference,BCR)形态。结果表明:稻米Cd质量比为0.01~0.51 mg/kg,土壤Cd质量比为0.17~3.15 mg/kg,稻米Cd富集系数为0.04~1.42;土壤Cd主要以弱酸态(40.5%)和还原态(37.1%)存在,二乙烯三胺五乙酸(diethylenetriaminepentaacetic acid,DTPA)浸提土壤Cd能力最强(15.6%);基于w(CaCl_(2)-Cd)构建的三次函数建立的回归模型可解释稻米Cd 57.4%方差,w(CaCl_(2)-Cd)可以作为表征水稻土壤Cd生物有效性的指标,基于水稻土壤Cd生物有效性可提高污染风险评价的科学性。展开更多
Cd contamination range of farmland soil in China is wide,which has constituted a major threat for food safety and residents' health. Via multi-year development,there are more remediation methods suitable for soil ...Cd contamination range of farmland soil in China is wide,which has constituted a major threat for food safety and residents' health. Via multi-year development,there are more remediation methods suitable for soil contaminated by Cd among the world,but some methods are only suitable for the contaminated sites and indoor research,and can not be applied in large-range contaminated farmland. We analyze the source of Cd in farmland soil. By combining farmland's characteristics,three remediation techniques( low-absorption crops plantation,soil solidification and phytoremediation) and their effects are analyzed,and the existing problems and research prospects of the above techniques are explored. The research could provide reference for restoring farmland soil contaminated by Cd in China,recovering its production function and enhancing food safety standards.展开更多
The continuous enrichment of heavy metals in soils has caused potential harm to groundwater.Quantitative methods to evaluate the harm of heavy metals in soil to groundwater are lacked in previous studies.Based on the ...The continuous enrichment of heavy metals in soils has caused potential harm to groundwater.Quantitative methods to evaluate the harm of heavy metals in soil to groundwater are lacked in previous studies.Based on the theory of groundwater circulation and solid-liquid equilibrium,a simple and easy-touse flux model of soil heavy metals migrating to groundwater is constructed.Based on groundwater environmental capacity,an innovative method for evaluating the harm of heavy metals in soil to groundwater is proposed,which has been applied in Hunchun Basin,Jilin Province,China.The results show that the fluxes of soil heavy metals into groundwater in the study area are Zn,Cu,As,Pb,Cd,Ni,and Hg in descending order.The content of heavy metals in groundwater(As,Hg,Cu,Pb,Zn,Ni,and Cd)in most areas has not risen to the threshold of environmental capacity within 10 years.The harm levels of soil heavy metals to groundwater in the most townships soils are at the moderate level or below.This evaluation method can quantify the flux of soil heavy metals into groundwater simply and quickly,determine the residual capacity of groundwater to heavy metals,evaluate the harm level of soil heavy metals to groundwater,provide support for relevant departments to carry out environmental protection of soil and groundwater,and provide a reference to carry out similar studies for related scholars.展开更多
[Objectives]This study was conducted to explore the removal performance and mechanism of heavy metal Cd in soil by combining electrokinetic technology and modified biochar.[Methods]The electrokinetics-magnetic/alkali ...[Objectives]This study was conducted to explore the removal performance and mechanism of heavy metal Cd in soil by combining electrokinetic technology and modified biochar.[Methods]The electrokinetics-magnetic/alkali composite-modified biochar method was applied to remediate Cd-contaminated soil.[Results]When remediating the soil for 120 h under electric field strength of 2 V/cm with 0.1 mol/L citric acid as the electrolyte,the current periodically varied with the remediation time.Cd^2+in the soil dissociated and migrated from the soil surface,and the addition of the magnetic/alkali composite-modified biochar in the cathode area affected the hydrolysis balance of heavy metal Cd^2+ions and maintained soil pH in a low range.The exchangeable Cd content at the test sampling points near the cathode area was relatively high,and the organic Cd area was evenly distributed.The average removal rate of Cd in the soil was up to 90.31%.The hexagonal anode device configuration enhanced the electromigration performance and made the soil pH and conductivity change within a certain range,which was beneficial to the migration of Cd2+and improved the removal rate of soil heavy metal Cd.[Conclusions]This study provides a theoretical basis for the treatment of soil heavy metal pollution and the resource utilization of composite-modified biochar.展开更多
In this article,we investigated effects of lead and cadmium on the biomass of ginkgo seedlings, and roles of the seedlings in accumulation characteristics of the heavy metals and remediation of the soil contaminated b...In this article,we investigated effects of lead and cadmium on the biomass of ginkgo seedlings, and roles of the seedlings in accumulation characteristics of the heavy metals and remediation of the soil contaminated by Cd<sup>2+</sup> or Pb<sup>2+</sup> as well as their combination.The results showed that both Cd<sup>2+</sup> and Pb<sup>2+</sup> significantly or very significantly reduced biomass increment of ginkgo seedlings,with Pb<sup>2+</sup> more adverse than Cd<sup>2+</sup>.The Cd<sup>2+</sup>-Pb<sup>2+</sup> compound pollution further reduced biomass increment of ginkgo seedlings.The mass fractions and enrichment coefficient of Pb<sup>2+</sup> and Cd<sup>2+</sup> in ginkgo seedlings were in an order of root】stem】leaf,which was in favor of transportation Pb<sup>2+</sup> and Cd<sup>2+</sup> from root to stem and leave.The Cd<sup>2+</sup>-Pb<sup>2+</sup> compound pollution promoted ginkgo seedling absorption to Cd<sup>2+</sup> and Pb<sup>2+</sup>.The capacity of the upward transport of Pb<sup>2+</sup> was greater than that of Cd<sup>2+</sup>,which suggested an obvious dose-effect and synergistic effect.Cd<sup>2+</sup> and Pb<sup>2+</sup> accumulations in ginkgo seedlings were relatively large.The accumulation in roots was higher than that in stems and leaves.The ability of the absorption,transportation and accumulation of ginkgo seedlings to Pb<sup>2+</sup> was relatively greater under Cd<sup>2+</sup>-Pb<sup>2+</sup> compound pollution.The phytoremediation efficiency of Cd<sup>2+</sup> and Pb<sup>2+</sup> was relatively high.展开更多
基金supported by the National Natural Science Foundation of China(31560122)the Guangxi Key Laboratory of Agro-Environment and Agric-Products Safety,China。
文摘The addition of silicon(Si)and organic fertilizers to soil conditioners can inhibit the transfer of heavy metal ions from soil to crops.However,it is not clear how Si and organic fertilizers affect soil properties and the micro-ecological environment and thereby reduce cadmium(Cd)accumulation in rice.In this study,the effects of L-type soil conditioners containing Si and organic fertilizers on bacterial and fungal community diversity,soil pH,organic matter,and available Si were analyzed with field experiments at two sites in Liuzhou City and Hezhou City,respectively,in Guangxi,China.With the increase of Si and organic fertilizer content in soil conditioner,rice yield respectively increased by 16.8–25.8 and 6.8–13.1%,and rice Cd content decreased significantly by 8.2–21.1 and 10.8–40.6%,respectively,at the two experimental sites.Soil microbiome analysis showed that the increase in abundance of Firmicutes and Actinobacteriota bacteria associated with Cd adsorption and sequestration,and Basidiomycota fungal populations associated with degradation of macromolecules favored the inhibition of soil Cd activity(soil exchangeable Cd decreased by 14.4–14.8 and 18.1–20.6%).This was associated with an increase in organic matter and Si content caused by applying soil conditioners.In conclusion,L-type soil conditioners,rich in Si and organic fertilizer,can reduce soil Cd bioavailability by regulating the dominant Cd passivating flora in the soil and ultimately reduce Cd accumulation in rice.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY17C020005)the Key Research and Development Project of Zhejiang Province,China(Grant No.2015C03020-4)+2 种基金the National Nature Science Foundation of China(Grant No.31401356)Jinhua Science and Technology Project(Grant No.2015-2-012)the National Training Program for College Students to Innovate and Start Enterprise(Grant No.201710356013)
文摘High grain-Cd-accumulating rice variety Yongyou 9 was planted in Cd-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid(ALA) and24-epibrassinolide(EBR) on Cd accumulation in brown rice. Results showed that the exogenous ALA and EBR had no significant effects on agronomic traits, soil pH and total Cd content in soil, but had some effects on the available Cd content in soil, and significantly influenced the Cd accumulation in the different parts of rice. Results also showed that 100 mg/L exogenous ALA significantly reduced the Cd accumulation in brown rice to blow the food safety standard(0.2 mg/kg), and also significantly reduced the Cd contents in the roots and culm of rice. However, 200 mg/L exogenous ALA treatment increased the Cd content in brown rice remarkably. In addition, 0.15 mg/L EBR treatment increased Cd accumulation in roots, culm, leaves and brown rice notably, whereas 0.30 mg/L exogenous EBR treatment reduced the Cd accumulation in brown rice properly, but it was not significant. Therefore,proper concentration of ALA can effectively reduce the Cd accumulation in brown rice, which can be used as an effective technical method for the safe production of rice in Cd polluted farmland.
文摘The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long history of numerous wars, foreign occupations, and most recently the Second Indochina War (aka the Vietnam War 1965-1972) which defoliated rain forests and ancient wetland mangroves and left behind contaminated soil and sediment hotspots. During this war, the United States (US) military sprayed 80 million liters of Agent Orange contaminated with the dioxin TCDD in a guerrilla war against communist insurgents. Agent Orange was a synthetic plant growth regulator comprised of equal amounts of two herbicides 2,4-dichloro phenoxyacetic acid C8H6Cl2O3 (2,4-D) and 2,4,5-trichlorophenoxyacetic acid C8H5Cl3O3 (2,4,5-T). TCDD, the dioxin, 2,3,7,8-tetrachlorodibenzodioxin (C12H4Cl4O2) was an unintended byproduct of the accelerated combustion process used in the manufacture of herbicides containing 2,4,5-T. Agent Orange has frequently been blamed for soil and sediment contamination and long-term human health problems;however, the true source of harm is the dioxin TCDD. Agent Orange has a short half-life of days and weeks after application to vegetation, and has not been found to persist, after 50 years, in the water or soils of southern Vietnam. However, the half-life of dioxin TCDD depends on where it is deposited and varies from 1 to 3 years on soil surfaces that have been fully exposed to sunlight, to as long as 20 to 50 years or more when buried in tropical subsoils, and more than 100 years in river and sea sediments. Dioxin TCDD was heavily concentrated in the US Air Force bases in Vietnam where the herbicides were stored, loaded on planes and helicopters for aerial spraying, and used extensively around military base perimeter fences as a security measure to prevent surprise attacks. Bien Hoa Air Force base, 40 km northeast of Ho Chi Minh City, continues to be one of the mega-hotspots where after 48 years the dioxin TCDD levels in fish and shrimp are still high and fishing is banned in ponds and lakes adjacent to the airbase. Although expensive, one of the most effective remediation to dioxin TCDD contaminated soils is incineration which is the recommended method of dioxin TCDD disposal.
基金This research was funded by the National Natural Science Foundation of China(NSFC)[Grant Nos.51661015 and 52061024]the University Innovation Fund Project of Gansu Provincial Department of Education[Grant No.2021B-553]the Natural Science Foundation of Zhejiang Province,China(4304030).
文摘Iron-based amorphous crystalline powder Fe_(78)Si_(9)B_(13)^(AP)is used as a permeability reaction barrier(PRB)combined with an electrokinetic method(EK-PRB)to study the removal rate of Cu in contaminated soil.After treating Cucontaminated soil for 5 days under different voltage gradients and soil water content,the soil pH is between 3.1 and 7.2.The increase of voltage gradient and soil water content can effectively promote the movement of Cu^(2+) to the cathode.The voltage gradient is 3 V/cm,and the water content of 40%is considered to be an optional experimental condition.Therefore,under this condition,the effects of Fe_(78)Si_(9)B_(13)^(AP)and zero-valent iron(ZVI)as PRB on the removal rate of total Cu in soil and the transformation of chemical forms of Cu are studied.Compared with ZVI,Fe_(78)Si_(9)B_(13)^(AP)as PRB has a better remediation effect.EK-Fe_(78)Si_(9)B_(13)^(AP)can remove 80.3%of total Cu in soil,and the biologically available Cu is reduced to 3.6%,which effectively reduces the environmental risk of contaminated soil.
文摘Statistical comparison of two remediation methods: Remedial nutrient solution and enhanced natural attenuation were analyzed in terms of TPH of different soil samples collected from Khana Local Government Area of Rivers State, Nigeria at different locations and placed inside sample bottles labelled A to D and replicated into two, one for each of the above treatment technique. The TPH of the soil was determined using GC analyzer after solvent extraction was carried out using hexane/dichloromethane mixture. Three batches of treatment were performed on the samples at every interval of eight weeks for a duration of six months. The result obtained was analyzed using a two-way ANOVA factorial experimental design to test the significance of the various sources of variation. From the result obtained, source of variation for sample and interactions were non-significantly different from each other which means that irrespective of the number of samples analyzed or the combination of both samples and batches of treatment, they will still not be significantly different from each other. The source of variation for batch and replications were significantly different from each other and this means that irrespective of the batches of treatment applied or the number of replications (methods of treatment used), they will always be significantly different from each other. The individual comparison of each sample showed that the efficiency of the Remedial Nutrient Solution method was better than Enhanced Natural Attenuation method.
文摘为遴选可有效表征农田土壤Cd生物有效性的指标,文章采集浙江某地20组稻米及其协同土壤,分析稻米Cd质量比、土壤的基本理化性质、Cd总质量比、不同浸提态Cd质量比及欧共体标准物质局(European Community Bureau of Reference,BCR)形态。结果表明:稻米Cd质量比为0.01~0.51 mg/kg,土壤Cd质量比为0.17~3.15 mg/kg,稻米Cd富集系数为0.04~1.42;土壤Cd主要以弱酸态(40.5%)和还原态(37.1%)存在,二乙烯三胺五乙酸(diethylenetriaminepentaacetic acid,DTPA)浸提土壤Cd能力最强(15.6%);基于w(CaCl_(2)-Cd)构建的三次函数建立的回归模型可解释稻米Cd 57.4%方差,w(CaCl_(2)-Cd)可以作为表征水稻土壤Cd生物有效性的指标,基于水稻土壤Cd生物有效性可提高污染风险评价的科学性。
基金Supported by Special Project of National Environmental Protection Public Interest Research,China(201109020)
文摘Cd contamination range of farmland soil in China is wide,which has constituted a major threat for food safety and residents' health. Via multi-year development,there are more remediation methods suitable for soil contaminated by Cd among the world,but some methods are only suitable for the contaminated sites and indoor research,and can not be applied in large-range contaminated farmland. We analyze the source of Cd in farmland soil. By combining farmland's characteristics,three remediation techniques( low-absorption crops plantation,soil solidification and phytoremediation) and their effects are analyzed,and the existing problems and research prospects of the above techniques are explored. The research could provide reference for restoring farmland soil contaminated by Cd in China,recovering its production function and enhancing food safety standards.
基金supported by the project of China Geology Survey(12120115032801,DD20190340)。
文摘The continuous enrichment of heavy metals in soils has caused potential harm to groundwater.Quantitative methods to evaluate the harm of heavy metals in soil to groundwater are lacked in previous studies.Based on the theory of groundwater circulation and solid-liquid equilibrium,a simple and easy-touse flux model of soil heavy metals migrating to groundwater is constructed.Based on groundwater environmental capacity,an innovative method for evaluating the harm of heavy metals in soil to groundwater is proposed,which has been applied in Hunchun Basin,Jilin Province,China.The results show that the fluxes of soil heavy metals into groundwater in the study area are Zn,Cu,As,Pb,Cd,Ni,and Hg in descending order.The content of heavy metals in groundwater(As,Hg,Cu,Pb,Zn,Ni,and Cd)in most areas has not risen to the threshold of environmental capacity within 10 years.The harm levels of soil heavy metals to groundwater in the most townships soils are at the moderate level or below.This evaluation method can quantify the flux of soil heavy metals into groundwater simply and quickly,determine the residual capacity of groundwater to heavy metals,evaluate the harm level of soil heavy metals to groundwater,provide support for relevant departments to carry out environmental protection of soil and groundwater,and provide a reference to carry out similar studies for related scholars.
基金Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX20_2582)。
文摘[Objectives]This study was conducted to explore the removal performance and mechanism of heavy metal Cd in soil by combining electrokinetic technology and modified biochar.[Methods]The electrokinetics-magnetic/alkali composite-modified biochar method was applied to remediate Cd-contaminated soil.[Results]When remediating the soil for 120 h under electric field strength of 2 V/cm with 0.1 mol/L citric acid as the electrolyte,the current periodically varied with the remediation time.Cd^2+in the soil dissociated and migrated from the soil surface,and the addition of the magnetic/alkali composite-modified biochar in the cathode area affected the hydrolysis balance of heavy metal Cd^2+ions and maintained soil pH in a low range.The exchangeable Cd content at the test sampling points near the cathode area was relatively high,and the organic Cd area was evenly distributed.The average removal rate of Cd in the soil was up to 90.31%.The hexagonal anode device configuration enhanced the electromigration performance and made the soil pH and conductivity change within a certain range,which was beneficial to the migration of Cd2+and improved the removal rate of soil heavy metal Cd.[Conclusions]This study provides a theoretical basis for the treatment of soil heavy metal pollution and the resource utilization of composite-modified biochar.
文摘In this article,we investigated effects of lead and cadmium on the biomass of ginkgo seedlings, and roles of the seedlings in accumulation characteristics of the heavy metals and remediation of the soil contaminated by Cd<sup>2+</sup> or Pb<sup>2+</sup> as well as their combination.The results showed that both Cd<sup>2+</sup> and Pb<sup>2+</sup> significantly or very significantly reduced biomass increment of ginkgo seedlings,with Pb<sup>2+</sup> more adverse than Cd<sup>2+</sup>.The Cd<sup>2+</sup>-Pb<sup>2+</sup> compound pollution further reduced biomass increment of ginkgo seedlings.The mass fractions and enrichment coefficient of Pb<sup>2+</sup> and Cd<sup>2+</sup> in ginkgo seedlings were in an order of root】stem】leaf,which was in favor of transportation Pb<sup>2+</sup> and Cd<sup>2+</sup> from root to stem and leave.The Cd<sup>2+</sup>-Pb<sup>2+</sup> compound pollution promoted ginkgo seedling absorption to Cd<sup>2+</sup> and Pb<sup>2+</sup>.The capacity of the upward transport of Pb<sup>2+</sup> was greater than that of Cd<sup>2+</sup>,which suggested an obvious dose-effect and synergistic effect.Cd<sup>2+</sup> and Pb<sup>2+</sup> accumulations in ginkgo seedlings were relatively large.The accumulation in roots was higher than that in stems and leaves.The ability of the absorption,transportation and accumulation of ginkgo seedlings to Pb<sup>2+</sup> was relatively greater under Cd<sup>2+</sup>-Pb<sup>2+</sup> compound pollution.The phytoremediation efficiency of Cd<sup>2+</sup> and Pb<sup>2+</sup> was relatively high.
