In this study, we have introduced a novel approach to cancer treatment involving the deactivation... more In this study, we have introduced a novel approach to cancer treatment involving the deactivation of metalloenzymes through the utilization of radioisotopes. The concept of leveraging radioisotopes to interact with metalloenzymes represents a groundbreaking theoretical advancement. Through simulations utilizing the MIRD code and based on the consistent concentration of stable Mg within stage 2A cancerous tissue, we have quantified the potential success rates. To conduct these simulations, we employed 0.1 nanograms (ng) of stable Mg, which corresponds to an activity of 19.7 MBq of Mg-28. This data was input into the MIRD calculations to estimate the absorbed doses within various organs, employing diverse methods of radioisotope administration into the body. Remarkably, even with a mere one thousandth probability of effectively reaching the intended cancerous tissues, this quantity of Mg-28 demonstrates the capability to render billions of Mg-containing metalloenzymes inactive. The re...
This paper presents the radioactivity concentrations of 226Ra, 232Th and 40K for 106 samples of s... more This paper presents the radioactivity concentrations of 226Ra, 232Th and 40K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226Ra, 232Th and 40K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg(-1), respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h(-1). The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg(-1) and 0.06-0.69, respectively.
Highlights on Medicine and Medical Science Vol. 15, 2021
Cancer cells are distinct from healthy cells in that they grow rapidly, uncontrollably, and rarel... more Cancer cells are distinct from healthy cells in that they grow rapidly, uncontrollably, and rarely die. They need more enzymes in terms of quantity than healthy cells for their metabolic processes, with two enzymes in particular: hexokinase and DNA polymerase. Enzymes are fascinating because they catalyze energy metabolism and DNA replication. They both have the magnesium metal ion as a cofactor. The use of beta-decay radioisotopes to deactivate cofactor enzymes by replacing stable metals with beta-decay radioisotopes is a recent development in cancer treatment research. 28Mg is used to substitute a stable Mg in the enzymes in this study. Hexokinase that has been deactivated has the potential to disrupt or stop the supply of energy to tumor cells.DNA replication can be slowed or disrupted if DNA polymerase is inactive. Tumors may be stopped in their tracks and even killed if these two vital mechanisms are disrupted. Besides, deactivating radioactive isotopes will bombard tumor cel...
This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples o... more This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226 Ra, 232 Th and 40 K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg À1 , respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h À1 . The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg À1 and 0.06-0.69, respectively.
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has ra... more Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at typical concentrations of between 8 and 16 ppm (dry weight). Industrial and agricultural arsenic is localised and relatively unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 lg L )1 , although scattered anomalous areas of 10 to 30 lg L )1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 lg L )1 , are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards, and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture. An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction in the future, will require continuing caution in water resources development throughout the region.
The pollution by toxic elements and heavy metals in sediments in Tham Luong Canal, Ho Chi Minh Ci... more The pollution by toxic elements and heavy metals in sediments in Tham Luong Canal, Ho Chi Minh City, Vietnam, was investigated by neutron activation and XRF analytical methods. The concentrations of 32 elements (Al, As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Ga, Hf, La, Mg, Mn, Na, Nb, Pb, Rb, Sm, Sb, Sc, Sr, Ta, Tb, Th, Ti, V, U, Yb, Zn, and Zr) along Tham Luong Canal were obtained. Among them, concentrations of 20 elements were at natural levels, but the others, such as As, Br, Cr, Fe, Hf, Pb, Sb, Sc, Ti, V, Zn, and Zr, could be considered as "pollutant elements". These elements are deposited in sediments to 50 cm depth. The masses of the pollutants are estimated to be about, e.g., 1,500 ton (t) iron, 300 t titanium, 4.5 t chromium, 0.3 t scandium.
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has ra... more Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at typical concentrations of between 8 and 16 ppm (dry weight). Industrial and agricultural arsenic is localised and relatively unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 lg L )1 , although scattered anomalous areas of 10 to 30 lg L )1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 lg L )1 , are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards, and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture. An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction in the future, will require continuing caution in water resources development throughout the region.
This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples o... more This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226 Ra, 232 Th and 40 K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg À1 , respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h À1 . The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg À1 and 0.06-0.69, respectively.
The paper presents a method of measuring 238 U activity in environmental soil samples by a low ba... more The paper presents a method of measuring 238 U activity in environmental soil samples by a low background HPGe spectrometer at the 63.3 keV gamma photopeak. The low 238 U activity requires a large size soil sample with a mass of about 100 g. The geometrical and self-absorption effects as well as the density dependence of soil samples were then investigated. A procedure of analyzing environmental soil samples was established with a relative error of about 10%. Two soil samples of known activity were tested and 106 surface soil samples collected from the Southern part of Vietnam were analyzed, and then these results were compared by instrumental neutron activation analytical method. r
A database on 238U, 232Th, 40K, and 137Cs in surface soils was established to provide inputs for ... more A database on 238U, 232Th, 40K, and 137Cs in surface soils was established to provide inputs for the assessment of the collective dose to the population of Vietnam and to support soil erosion studies using 137Cs as a tracer. A total of 292 soil samples was taken from undisturbed sites across the territory and the concentrations of radionuclides were determined by gamma spectrometry method. The multiple regression of 137Cs inventories against characteristics of sampling locations allowed us to establish the distribution of 137Cs deposition density and its relationship with latitude and annual rainfall. The 137Cs deposition density increases northward and varies from 178 Bq m(-2) to 1,920 Bq m(-2). High rainfall areas in the northern and central parts of the country have received considerable 137Cs inputs exceeding 600 Bq m-2, which is the maximum value that can be expected for Vietnam from the UNSCEAR global pattern. The mean activity concentrations of naturally occurring radionuclides 238U, 232Th, and 40K are 45, 59, and 401 Bq kg(-1), respectively, which entail an average absorbed dose rate in air of 62 nGy h(-1), which is about 7% higher than the world average.
The neutron activation method is usually applied for analysis of elemental concentrations in arch... more The neutron activation method is usually applied for analysis of elemental concentrations in archaeological pottery samples. By this analytical technique concentrations of twenty-seven elements (Al, As, Zn) were obtained from four groups of pottery samples collected from four different sites that named Thanh Den, Long Thanh, Trang Kenh, and Dong Dau, respectively. The different results from application of statistical inference method for comparing elemental concentrations indicate that these samples were made of different materials. Whereas results of sample subgroups of three different layers collected at the Dong Dau site show that they originated from the same material source.
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has ra... more Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at typical concentrations of between 8 and 16 ppm; (dry weight). Industrial and agricultural arsenic is localised and relatively unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 μg L−1, although scattered anomalous areas of 10 to 30 μg L−1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 μg L−1, are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards, and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture. An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction in the future, will require continuing caution in water resources development throughout the region.
The paper presents a method of measuring 238 U activity in environmental soil samples by a low ba... more The paper presents a method of measuring 238 U activity in environmental soil samples by a low background HPGe spectrometer at the 63.3 keV gamma photopeak. The low 238 U activity requires a large size soil sample with a mass of about 100 g. The geometrical and self-absorption effects as well as the density dependence of soil samples were then investigated. A procedure of analyzing environmental soil samples was established with a relative error of about 10%. Two soil samples of known activity were tested and 106 surface soil samples collected from the Southern part of Vietnam were analyzed, and then these results were compared by instrumental neutron activation analytical method. r
In this study, we have introduced a novel approach to cancer treatment involving the deactivation... more In this study, we have introduced a novel approach to cancer treatment involving the deactivation of metalloenzymes through the utilization of radioisotopes. The concept of leveraging radioisotopes to interact with metalloenzymes represents a groundbreaking theoretical advancement. Through simulations utilizing the MIRD code and based on the consistent concentration of stable Mg within stage 2A cancerous tissue, we have quantified the potential success rates. To conduct these simulations, we employed 0.1 nanograms (ng) of stable Mg, which corresponds to an activity of 19.7 MBq of Mg-28. This data was input into the MIRD calculations to estimate the absorbed doses within various organs, employing diverse methods of radioisotope administration into the body. Remarkably, even with a mere one thousandth probability of effectively reaching the intended cancerous tissues, this quantity of Mg-28 demonstrates the capability to render billions of Mg-containing metalloenzymes inactive. The re...
This paper presents the radioactivity concentrations of 226Ra, 232Th and 40K for 106 samples of s... more This paper presents the radioactivity concentrations of 226Ra, 232Th and 40K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226Ra, 232Th and 40K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg(-1), respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h(-1). The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg(-1) and 0.06-0.69, respectively.
Highlights on Medicine and Medical Science Vol. 15, 2021
Cancer cells are distinct from healthy cells in that they grow rapidly, uncontrollably, and rarel... more Cancer cells are distinct from healthy cells in that they grow rapidly, uncontrollably, and rarely die. They need more enzymes in terms of quantity than healthy cells for their metabolic processes, with two enzymes in particular: hexokinase and DNA polymerase. Enzymes are fascinating because they catalyze energy metabolism and DNA replication. They both have the magnesium metal ion as a cofactor. The use of beta-decay radioisotopes to deactivate cofactor enzymes by replacing stable metals with beta-decay radioisotopes is a recent development in cancer treatment research. 28Mg is used to substitute a stable Mg in the enzymes in this study. Hexokinase that has been deactivated has the potential to disrupt or stop the supply of energy to tumor cells.DNA replication can be slowed or disrupted if DNA polymerase is inactive. Tumors may be stopped in their tracks and even killed if these two vital mechanisms are disrupted. Besides, deactivating radioactive isotopes will bombard tumor cel...
This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples o... more This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226 Ra, 232 Th and 40 K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg À1 , respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h À1 . The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg À1 and 0.06-0.69, respectively.
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has ra... more Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at typical concentrations of between 8 and 16 ppm (dry weight). Industrial and agricultural arsenic is localised and relatively unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 lg L )1 , although scattered anomalous areas of 10 to 30 lg L )1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 lg L )1 , are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards, and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture. An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction in the future, will require continuing caution in water resources development throughout the region.
The pollution by toxic elements and heavy metals in sediments in Tham Luong Canal, Ho Chi Minh Ci... more The pollution by toxic elements and heavy metals in sediments in Tham Luong Canal, Ho Chi Minh City, Vietnam, was investigated by neutron activation and XRF analytical methods. The concentrations of 32 elements (Al, As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Ga, Hf, La, Mg, Mn, Na, Nb, Pb, Rb, Sm, Sb, Sc, Sr, Ta, Tb, Th, Ti, V, U, Yb, Zn, and Zr) along Tham Luong Canal were obtained. Among them, concentrations of 20 elements were at natural levels, but the others, such as As, Br, Cr, Fe, Hf, Pb, Sb, Sc, Ti, V, Zn, and Zr, could be considered as "pollutant elements". These elements are deposited in sediments to 50 cm depth. The masses of the pollutants are estimated to be about, e.g., 1,500 ton (t) iron, 300 t titanium, 4.5 t chromium, 0.3 t scandium.
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has ra... more Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at typical concentrations of between 8 and 16 ppm (dry weight). Industrial and agricultural arsenic is localised and relatively unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 lg L )1 , although scattered anomalous areas of 10 to 30 lg L )1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 lg L )1 , are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards, and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture. An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction in the future, will require continuing caution in water resources development throughout the region.
This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples o... more This paper presents the radioactivity concentrations of 226 Ra, 232 Th and 40 K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226 Ra, 232 Th and 40 K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg À1 , respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h À1 . The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg À1 and 0.06-0.69, respectively.
The paper presents a method of measuring 238 U activity in environmental soil samples by a low ba... more The paper presents a method of measuring 238 U activity in environmental soil samples by a low background HPGe spectrometer at the 63.3 keV gamma photopeak. The low 238 U activity requires a large size soil sample with a mass of about 100 g. The geometrical and self-absorption effects as well as the density dependence of soil samples were then investigated. A procedure of analyzing environmental soil samples was established with a relative error of about 10%. Two soil samples of known activity were tested and 106 surface soil samples collected from the Southern part of Vietnam were analyzed, and then these results were compared by instrumental neutron activation analytical method. r
A database on 238U, 232Th, 40K, and 137Cs in surface soils was established to provide inputs for ... more A database on 238U, 232Th, 40K, and 137Cs in surface soils was established to provide inputs for the assessment of the collective dose to the population of Vietnam and to support soil erosion studies using 137Cs as a tracer. A total of 292 soil samples was taken from undisturbed sites across the territory and the concentrations of radionuclides were determined by gamma spectrometry method. The multiple regression of 137Cs inventories against characteristics of sampling locations allowed us to establish the distribution of 137Cs deposition density and its relationship with latitude and annual rainfall. The 137Cs deposition density increases northward and varies from 178 Bq m(-2) to 1,920 Bq m(-2). High rainfall areas in the northern and central parts of the country have received considerable 137Cs inputs exceeding 600 Bq m-2, which is the maximum value that can be expected for Vietnam from the UNSCEAR global pattern. The mean activity concentrations of naturally occurring radionuclides 238U, 232Th, and 40K are 45, 59, and 401 Bq kg(-1), respectively, which entail an average absorbed dose rate in air of 62 nGy h(-1), which is about 7% higher than the world average.
The neutron activation method is usually applied for analysis of elemental concentrations in arch... more The neutron activation method is usually applied for analysis of elemental concentrations in archaeological pottery samples. By this analytical technique concentrations of twenty-seven elements (Al, As, Zn) were obtained from four groups of pottery samples collected from four different sites that named Thanh Den, Long Thanh, Trang Kenh, and Dong Dau, respectively. The different results from application of statistical inference method for comparing elemental concentrations indicate that these samples were made of different materials. Whereas results of sample subgroups of three different layers collected at the Dong Dau site show that they originated from the same material source.
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has ra... more Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at typical concentrations of between 8 and 16 ppm; (dry weight). Industrial and agricultural arsenic is localised and relatively unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 μg L−1, although scattered anomalous areas of 10 to 30 μg L−1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 μg L−1, are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards, and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture. An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction in the future, will require continuing caution in water resources development throughout the region.
The paper presents a method of measuring 238 U activity in environmental soil samples by a low ba... more The paper presents a method of measuring 238 U activity in environmental soil samples by a low background HPGe spectrometer at the 63.3 keV gamma photopeak. The low 238 U activity requires a large size soil sample with a mass of about 100 g. The geometrical and self-absorption effects as well as the density dependence of soil samples were then investigated. A procedure of analyzing environmental soil samples was established with a relative error of about 10%. Two soil samples of known activity were tested and 106 surface soil samples collected from the Southern part of Vietnam were analyzed, and then these results were compared by instrumental neutron activation analytical method. r
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