Because of the rapid development of industrial processes, increased urban pollution and agricultural chemicals applied in recent years, heavy metal(loid) pollution in soil has been very serious, and there is an urgent...Because of the rapid development of industrial processes, increased urban pollution and agricultural chemicals applied in recent years, heavy metal(loid) pollution in soil has been very serious, and there is an urgent need for fast and efficient removal of heavy metal(loid) pollution. Currently, environmental microorganisms are always used to perform biological alteration or improvement of soils and sewage. Using functional microorganisms that are resistant to toxic heavy metal(loid) ions for alteration and transformation of heavy metal(loid)s in ionic form is an effective measure for microbial remediation of heavy metal(loid)contaminated soil. This paper reviewed the microbial remediation mechanism of heavy metal(loid) contaminated soils, and the approaches for breeding bacteria those can be used for highly efficient removal of heavy metal(loid)s, as well as the application examples of microbial remediation and transformation of heavy metal(loid) contaminated soil, and finally described the future trends and further research work of heavy metal(loid) contaminated soils by microbial remediation.展开更多
The cpc＇s 13th Five-Year comprehensive plan put forward a major historic task of building a new socialist countryside. This is the comprehensive implementation of urban and rural development to increase industrial ag...The cpc＇s 13th Five-Year comprehensive plan put forward a major historic task of building a new socialist countryside. This is the comprehensive implementation of urban and rural development to increase industrial agriculture, move the city to support the countryside, accelerate urbanization and narrow the gap between urban and rural areas. To solve the ＂three rural issues＂, the comprehensive construction ofa well-offsociety, has a very important strategic role to ease the contradiction of China＇s rural and urban ecnomic structure. In the process of building a new socialist countryside, the financial policy, as an important means ofmacroeconomic regulation and control, should play a leading role in solving the effective allocation ＆funds. Due to various factors affected by the current supply of rural financial market constraints, system defects and environmental constraints, there is a large gap between the level of the existing rural financial services and the requirements of the new rural construction which is to be improved urgently.展开更多
Wetland reclamation has been ongoing in the Sanjiang Plain since the mid-1950s,which has resulted in major changes in wetlands and the agriculture ecosystem in the region that have influenced the iron output to the Se...Wetland reclamation has been ongoing in the Sanjiang Plain since the mid-1950s,which has resulted in major changes in wetlands and the agriculture ecosystem in the region that have influenced the iron output to the Sea of Okhotsk and limited the primary productivity in the North Pacific Ocean.This study was conducted to investigate the chemical forms of iron in different aquatic environments(agricultural water including groundwater,paddy water,and canal water;wetland water including marsh water,marsh streams,and main streams) with the cross-flow filtration method to reveal the transportation and transformation characteristics of iron in response to major land use changes.In addition,the factors affecting iron behavior in different water bodies were reviewed.In marsh water and streams,the concentrations of dissolved iron were higher due to the high organic matter contents and marsh water becoming the main iron source for river water.The conversion of dissolved iron into acid-labile iron occurred during the discharge of wetland water into marsh rivers.Iron primarily existed in both the >0.7 and <0.01 μm size fractions,accounting for about 58.3% and 26.4% of the total dissolved iron,respectively.In agricultural irrigation systems,ferrous ion entered the paddy fields from groundwater,and a fraction of this ferrous iron was subsequently converted into high molecular weight and medium molecular weight iron(colloid iron) in paddy and canal water.However,the concentrations of total dissolved iron decreased by 62.5% from underground to the surface due to the formation of precipitates.Despite this,water discharge in agriculture is still an important iron source for rivers and has the potential to supplement iron due to its higher acid-labile iron concentrations.Land use and cover change and agricultural irrigation increased the iron content of surface soil,but reduced the output of iron in water systems.Overall,the concentration of total dissolved iron in water systems has been reduced to 42.6% by wetland reclamation.展开更多
文摘Because of the rapid development of industrial processes, increased urban pollution and agricultural chemicals applied in recent years, heavy metal(loid) pollution in soil has been very serious, and there is an urgent need for fast and efficient removal of heavy metal(loid) pollution. Currently, environmental microorganisms are always used to perform biological alteration or improvement of soils and sewage. Using functional microorganisms that are resistant to toxic heavy metal(loid) ions for alteration and transformation of heavy metal(loid)s in ionic form is an effective measure for microbial remediation of heavy metal(loid)contaminated soil. This paper reviewed the microbial remediation mechanism of heavy metal(loid) contaminated soils, and the approaches for breeding bacteria those can be used for highly efficient removal of heavy metal(loid)s, as well as the application examples of microbial remediation and transformation of heavy metal(loid) contaminated soil, and finally described the future trends and further research work of heavy metal(loid) contaminated soils by microbial remediation.
文摘The cpc＇s 13th Five-Year comprehensive plan put forward a major historic task of building a new socialist countryside. This is the comprehensive implementation of urban and rural development to increase industrial agriculture, move the city to support the countryside, accelerate urbanization and narrow the gap between urban and rural areas. To solve the ＂three rural issues＂, the comprehensive construction ofa well-offsociety, has a very important strategic role to ease the contradiction of China＇s rural and urban ecnomic structure. In the process of building a new socialist countryside, the financial policy, as an important means ofmacroeconomic regulation and control, should play a leading role in solving the effective allocation ＆funds. Due to various factors affected by the current supply of rural financial market constraints, system defects and environmental constraints, there is a large gap between the level of the existing rural financial services and the requirements of the new rural construction which is to be improved urgently.
基金supported by National Basic Research Program of China (Grant No. 2004CB418502)
文摘Wetland reclamation has been ongoing in the Sanjiang Plain since the mid-1950s,which has resulted in major changes in wetlands and the agriculture ecosystem in the region that have influenced the iron output to the Sea of Okhotsk and limited the primary productivity in the North Pacific Ocean.This study was conducted to investigate the chemical forms of iron in different aquatic environments(agricultural water including groundwater,paddy water,and canal water;wetland water including marsh water,marsh streams,and main streams) with the cross-flow filtration method to reveal the transportation and transformation characteristics of iron in response to major land use changes.In addition,the factors affecting iron behavior in different water bodies were reviewed.In marsh water and streams,the concentrations of dissolved iron were higher due to the high organic matter contents and marsh water becoming the main iron source for river water.The conversion of dissolved iron into acid-labile iron occurred during the discharge of wetland water into marsh rivers.Iron primarily existed in both the >0.7 and <0.01 μm size fractions,accounting for about 58.3% and 26.4% of the total dissolved iron,respectively.In agricultural irrigation systems,ferrous ion entered the paddy fields from groundwater,and a fraction of this ferrous iron was subsequently converted into high molecular weight and medium molecular weight iron(colloid iron) in paddy and canal water.However,the concentrations of total dissolved iron decreased by 62.5% from underground to the surface due to the formation of precipitates.Despite this,water discharge in agriculture is still an important iron source for rivers and has the potential to supplement iron due to its higher acid-labile iron concentrations.Land use and cover change and agricultural irrigation increased the iron content of surface soil,but reduced the output of iron in water systems.Overall,the concentration of total dissolved iron in water systems has been reduced to 42.6% by wetland reclamation.
