The improvement of question soils with cement shows great technical, economic and environmental advantages. And interest in introducing electrical resistivity measurement to assess the quality of cement treated soils ...The improvement of question soils with cement shows great technical, economic and environmental advantages. And interest in introducing electrical resistivity measurement to assess the quality of cement treated soils has increased markedly recently due to its economical, non-destructive, and relatively non-invasive advantages. This work aims to quantify the effect of cement content （aw）, porosity （nt）, and curing time（T） on the electrical resistivity （p） and unconfined compression strength （UCS） of cement treated soil. A series of electrical resistivity tests and UCS tests of cement treated soil specimen after various curing periods were carried out. A modified Archie empirical law was proposed taking into account the effect of cement content and curing period on the electrical resistivity of cement treated soil. The results show that nt/（aw·T） and nt/（aw·T^1/2） ratio are appropriate parameters to assess electrical resistivity and UCS of cement treated soil, respectively. Finally, the relationship between UCS and electrical resistivity was also established.展开更多
Se （selenium） is an essential trace element for both animals and human beings, although it is considered to be conditionally required for plants. Se occurrence in the environment of Moldova is poorly understood. The...Se （selenium） is an essential trace element for both animals and human beings, although it is considered to be conditionally required for plants. Se occurrence in the environment of Moldova is poorly understood. The objective of this study was to establish Se content and distribution in soils of this country. Se content in samples was detected using fluorometric method. Se concentration in soils ranged from 100 μg·kg^-1 to 668 og-kg-1 dry weight （mean 246 ± 73 μg·kg^-1）. Mainly, Se content in soils was optimal （more than 175 μg·kg^-1）, however, there were soil areas with Se deficiency （lower than 125/μg·kg^-1）. Maximum of Se in soils was observed at the depth of 0.4-0.7 m and then it decreased on going to parent rock. Se content typically increased with increasing of soil clay particles. Se washout from terraces and watershed slopes as well as Se accumulation in relief depressions was shown. High Se concentrations in local surface waters （0.2-6.1 μg·L^-1, mean 1.8 μg·L^-1） indicated the substantial presence of soluble Se forms, which were available to plants. Thus, geochemical conditions of Moldova are favorable for Se bioaccumulation by plants.展开更多
In the present work, uranium concentrations were measured in twenty surface soil samples forselected regions in AI-Anbargovernorate using fission track etch technique, CR-39 track detector was used for registration of...In the present work, uranium concentrations were measured in twenty surface soil samples forselected regions in AI-Anbargovernorate using fission track etch technique, CR-39 track detector was used for registration of induced fission tracks. The results show that, the uranium concentrations ranged from 4.61 ppm, 56.93 Bq/kg （AL-Falluja AL-Jolan District） to 1.81 ppm 22.35 Bq/kg （Anah）with an average 3.42±0.79 ppm, 41.76±9.04 Bq/kg. The present results have shown that the uranium concentrations in the studied surface soil samples were less than the allowed limit 11.7 ppm recommended by UNSCEAR, 1993.展开更多
基金Project(BK2011618) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject(51108288) supported by the National Natural Science Foundation of China
文摘The improvement of question soils with cement shows great technical, economic and environmental advantages. And interest in introducing electrical resistivity measurement to assess the quality of cement treated soils has increased markedly recently due to its economical, non-destructive, and relatively non-invasive advantages. This work aims to quantify the effect of cement content （aw）, porosity （nt）, and curing time（T） on the electrical resistivity （p） and unconfined compression strength （UCS） of cement treated soil. A series of electrical resistivity tests and UCS tests of cement treated soil specimen after various curing periods were carried out. A modified Archie empirical law was proposed taking into account the effect of cement content and curing period on the electrical resistivity of cement treated soil. The results show that nt/（aw·T） and nt/（aw·T^1/2） ratio are appropriate parameters to assess electrical resistivity and UCS of cement treated soil, respectively. Finally, the relationship between UCS and electrical resistivity was also established.
文摘Se （selenium） is an essential trace element for both animals and human beings, although it is considered to be conditionally required for plants. Se occurrence in the environment of Moldova is poorly understood. The objective of this study was to establish Se content and distribution in soils of this country. Se content in samples was detected using fluorometric method. Se concentration in soils ranged from 100 μg·kg^-1 to 668 og-kg-1 dry weight （mean 246 ± 73 μg·kg^-1）. Mainly, Se content in soils was optimal （more than 175 μg·kg^-1）, however, there were soil areas with Se deficiency （lower than 125/μg·kg^-1）. Maximum of Se in soils was observed at the depth of 0.4-0.7 m and then it decreased on going to parent rock. Se content typically increased with increasing of soil clay particles. Se washout from terraces and watershed slopes as well as Se accumulation in relief depressions was shown. High Se concentrations in local surface waters （0.2-6.1 μg·L^-1, mean 1.8 μg·L^-1） indicated the substantial presence of soluble Se forms, which were available to plants. Thus, geochemical conditions of Moldova are favorable for Se bioaccumulation by plants.
文摘In the present work, uranium concentrations were measured in twenty surface soil samples forselected regions in AI-Anbargovernorate using fission track etch technique, CR-39 track detector was used for registration of induced fission tracks. The results show that, the uranium concentrations ranged from 4.61 ppm, 56.93 Bq/kg （AL-Falluja AL-Jolan District） to 1.81 ppm 22.35 Bq/kg （Anah）with an average 3.42±0.79 ppm, 41.76±9.04 Bq/kg. The present results have shown that the uranium concentrations in the studied surface soil samples were less than the allowed limit 11.7 ppm recommended by UNSCEAR, 1993.
