The effect of particle size on the recalcitrance of biochar against oxidation has been regarded as one of the most important factors influencing its stability and transportation in soils. Little is known about the pec...The effect of particle size on the recalcitrance of biochar against oxidation has been regarded as one of the most important factors influencing its stability and transportation in soils. Little is known about the peculiar stability of different particle sizes under chemical oxidation conditions. In this study, several sizes of biochar particles derived from beanpod were produced,and their stabilities were tested by using acid dichromate and hydrogen peroxide. We discovered that the 60-100 mesh size of particles produced at 400 and 500 ℃ showed the least carbon loss under the oxidation of both dichromate and hydrogen peroxide. In addition, this particle size also shows great stability at 600 and 700 ℃, but this stability was not observed below 300 °C for all temperature-dependent biochars. Medium-sized particles composed of exclusively heterogeneous components produced a biochar at temperatures over 400 ℃ with comparatively stronger chemical anti-oxidation characteristics. The chemical recalcitrance of biochar should be reevaluated based on particle size before soil application.展开更多
China is one of the most important producers and suppliers of the chlorobenzenes （CBs）, accounting for more than 50% of the world production. Although CBs contamination at the sites of chemical production factories ...China is one of the most important producers and suppliers of the chlorobenzenes （CBs）, accounting for more than 50% of the world production. Although CBs contamination at the sites of chemical production factories is well-known, the knowledge on spatial distribution and contaminated degree of CBs are still limited. To better understand the occurrence of CBs, a total of 161 soil/sediment samples were collected from 36 sampling points within a 20 m deep from a site of decommissioned chlorobenzenes-producing factory in Wuhan City, Hubei Province, central China. The results showed that monochlorobenzene （MCB） is the predominant contaminants with the ∑CBs levels ranging from 0.05 to 8 600 mg/kg dry weight （dw） with a mean value of 384 mg/kg dw. The vertical distribution of CBs indicated that CBs may have clearly transported to deeper sections in the subsurface. Statistical analyses showed that there are no good correlations between the ∑CBs concentration with soil organic matter （SOM） content and the moisture content.展开更多
It has been generally accepted that about 85％ of cancers are caused by chemical factors and the chemically induced carcinogenic process can be divided into two or three stages, i. e. initiation and promotion, or toge...It has been generally accepted that about 85％ of cancers are caused by chemical factors and the chemically induced carcinogenic process can be divided into two or three stages, i. e. initiation and promotion, or together with further progression. The initiation is usually considered to be an irreversible process, but it can be blocked to further progress to cancer. For this reason, searching of objective markers for identifying initiated cells has played an important role in defining the preneoplastic lesion. So far, a large number of studies have been carried out on this object, including biochemistry, histopathology, histochemistry, immunohistochemistry, etc., and nearly thirty histochemical and other phenotypic changes have been found associated with the putative preneoplastic liver展开更多
基金Supported by the Provincial Basic Research Program of Hebei Education Department(ZD2015110)the National Special Project on Key Technologies and Demonstration of Wetland Ecological Restoration in the Haihe River Basin(2014ZX07203008)the Fund of the University of Hebei Engineering(Grants 20120169)
文摘The effect of particle size on the recalcitrance of biochar against oxidation has been regarded as one of the most important factors influencing its stability and transportation in soils. Little is known about the peculiar stability of different particle sizes under chemical oxidation conditions. In this study, several sizes of biochar particles derived from beanpod were produced,and their stabilities were tested by using acid dichromate and hydrogen peroxide. We discovered that the 60-100 mesh size of particles produced at 400 and 500 ℃ showed the least carbon loss under the oxidation of both dichromate and hydrogen peroxide. In addition, this particle size also shows great stability at 600 and 700 ℃, but this stability was not observed below 300 °C for all temperature-dependent biochars. Medium-sized particles composed of exclusively heterogeneous components produced a biochar at temperatures over 400 ℃ with comparatively stronger chemical anti-oxidation characteristics. The chemical recalcitrance of biochar should be reevaluated based on particle size before soil application.
基金financial support from the National Key Research and Development Program of China (No. 2017YFD0801005)the National Natural Science Foundation of China (No. 41672246)the Fund for Hubei Technology Innovation (Nos. 2017ACA092, 2016ACA171)
文摘China is one of the most important producers and suppliers of the chlorobenzenes （CBs）, accounting for more than 50% of the world production. Although CBs contamination at the sites of chemical production factories is well-known, the knowledge on spatial distribution and contaminated degree of CBs are still limited. To better understand the occurrence of CBs, a total of 161 soil/sediment samples were collected from 36 sampling points within a 20 m deep from a site of decommissioned chlorobenzenes-producing factory in Wuhan City, Hubei Province, central China. The results showed that monochlorobenzene （MCB） is the predominant contaminants with the ∑CBs levels ranging from 0.05 to 8 600 mg/kg dry weight （dw） with a mean value of 384 mg/kg dw. The vertical distribution of CBs indicated that CBs may have clearly transported to deeper sections in the subsurface. Statistical analyses showed that there are no good correlations between the ∑CBs concentration with soil organic matter （SOM） content and the moisture content.
基金Project supported by the National Natural Science Foundation of China
文摘It has been generally accepted that about 85％ of cancers are caused by chemical factors and the chemically induced carcinogenic process can be divided into two or three stages, i. e. initiation and promotion, or together with further progression. The initiation is usually considered to be an irreversible process, but it can be blocked to further progress to cancer. For this reason, searching of objective markers for identifying initiated cells has played an important role in defining the preneoplastic lesion. So far, a large number of studies have been carried out on this object, including biochemistry, histopathology, histochemistry, immunohistochemistry, etc., and nearly thirty histochemical and other phenotypic changes have been found associated with the putative preneoplastic liver
