This paper presents research aimed at identifying the methods with which prehistoric man interacted with marine and inland water environments. The objective is to determine the degree to which resources from these env...This paper presents research aimed at identifying the methods with which prehistoric man interacted with marine and inland water environments. The objective is to determine the degree to which resources from these environments influenced the socio-economic organization of these peoples. The coastline around Cagliari and its hinterland （southern Sardinia, Italy） were chosen as the subject, on the basis of the presence of both the sea and several ponds. The territory is noted as being home to both Neolithic and Eneolithic settlements. Among these the archaeological excavation of the village of Su Coddu/Canelles produced a large quantity of malacofauna. Data has been processed from part of the settlement that gave radiocarbon dating from the period between 3640 and 2900 cal. BC, and in which it was possible to carry out the level of sampling that was necessary to complete the research. In particular this interdisciplinary project, which aims to make an overall study of the settlement, the data relating to the geography of the area, the archaeological documentation, the fauna and shell artefacts will be extrapolated. Numerous methods are applied above all in reference to the marines and ponds resources. Additionally, the morphological anatomical-comparative analysis （in order to determine the typology of the faunal remains and to identify each individual species） and the technological analysis of the manufactured shells （so as to detect the selection and the transformation type of raw materials） are accomplished. The research has led to the identification of a settlement model in which agriculture formed the primary means of subsistence, that was complemented by the rearing of livestock, through hunting and gathering. The exploitation of marine and inland waters resources, as food source, have to be important because 99% of the faunal remains are shells. Different shell species are recognized, among those the Ostrea edulis provides the raw material to produce bevelled objects, which are documented inside the settlement in considerable number. Some plant species, typical of the lagoon ecosystem, were used for building and craft production.展开更多
For the geological disposal of high level radioactive wastes, an excavation damaged zone （EDZ） having high hydraulic conductivity resulting from the development of fractures in the rock adjacent to the tunnels will ...For the geological disposal of high level radioactive wastes, an excavation damaged zone （EDZ） having high hydraulic conductivity resulting from the development of fractures in the rock adjacent to the tunnels will be one of the potential pathways for radioactive contaminant transport. The potential pathways will be sealed by closure components, that is, a combination of tunnel plug, backfill and grout, the latter material being a clay-based mixture in consideration of the need for long-term stability of the seals. Clay-based grout is one of the effective candidate materials that can be used to interrupt the migration of radionuclides through an EDZ. Laboratory testing of clay-based grout using pulverized bentonite, with the objective of improvement in grout penetration into a rockmass, was conducted. The results showed that the pulverization of clay-based grout had a positive effect on filtration.展开更多
The palaeolake evolution across the Tibetan Plateau and adjacent areas has been extensively studied, but the timing of late Pleistocene lake highstands remains controversial. Robust dating of lacustrine deposits is of...The palaeolake evolution across the Tibetan Plateau and adjacent areas has been extensively studied, but the timing of late Pleistocene lake highstands remains controversial. Robust dating of lacustrine deposits is of importance in resolving this issue. This paper presents 14 C or optically stimulated luminescence(OSL) age estimates from two sets of late Quaternary lacustrine sequences in the Qaidam Basin and Tengger Desert(northeastern Tibetan Plateau). The updated dating results show:(1) the radiocarbon dating technique apparently underestimated the age of the strata of >30 ka BP in Qaidam Basin;(2) although OSL and 14 C dating agreed with each other for Holocene age samples in the Tengger Desert area, there was a significant offset in dating results of sediments older than ~30 ka BP, largely resulting from radiocarbon dating underestimation;(3) both cases imply that most of the published radiocarbon ages(e.g., older than ~30 ka BP) should be treated with caution and perhaps its geological implication should be revaluated; and(4) the high lake events on the Tibetan Plateau and adjacent areas, traditionally assigned to MIS 3a based on 14 C dating, are likely older than ~80 ka based on OSL chronology.展开更多
Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tr...Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tracer technique in Mojiagou Basin located on the outskirts of Changchun in Northeast China. The calculated soft erosion rates in the study area were 1.99 and 1.85 mm year-1 using 137Cs and excess 210pb （210Pbex） measurements, respectively. Both fallout radionuclides showed a similar tendency at downslope sites. All measured sites have experienced net erosion during the past 50 to 100 years. 137Cs and 210Pbex measurements were useful to quantify soil erosion rates on field and small basin scales. At this rate of erosion, the current fertile topsoil layer would be entirely removed within 70 years.展开更多
A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data ...A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data on pollutant emissions during the accident, this study simulates the dispersion of nuclear pollutants. The source term of the nuclear leakage of radioactive material is designed using PM2.5 as the tracer of radioactive pollutants, and the study considers dry and wet deposition processes. A coupled-model system is constructed from the air-quality model Models-3/CMAQ and the Weather Research and Forecasting atmospheric model. The transport path and distribution of radioactive pollutants over long and short distances are simulated with different model horizontal resolutions of 30 and 4 km respectively. The long-distance simulation shows that, following the Fukushima nuclear accident, under the effect of westerly winds, radioactive pollutants are transported generally towards the eastern Pacific and reach the American continent after 5 days, but their concentration is only about 10-7 times the concentration near the Fukushima Nuclear Power Plant. The time required for pollutants to reach the United States is basically consistent with measurements made in California on March 18. Because the upper westerly wind is faster than the lower westerly wind, the distribution of pollutants tilts eastward in terms of its vertical structure. The short-distance （local） highresolution simulation indicates that strong winds and precipitation associated with a cyclone can accelerate the deposition, dif- fusion and transport of pollutions, and local cyclonic circulation can change the transport path of pollutants, even resulting in repeated effects of pollution in some areas. Pollutants disperse to southeastern Honshu, Japan, on March 14, 2011, agreeing well with the timing of local observations of increases in the absorbed dose rate. Results also show that radioactive pollutants from the Fukushima nuclear accident are mainly transported and diffuse eastward, resulting in a relatively short-term impact on the Japanese mainland even under the influence of the cyclone system. Therefore, in terms of atmospheric conditions, the location of the Fukusbima Nuclear Power Plant is appropriate and could serve as a reference to site selection and protection of other nuclear facilities.展开更多
文摘This paper presents research aimed at identifying the methods with which prehistoric man interacted with marine and inland water environments. The objective is to determine the degree to which resources from these environments influenced the socio-economic organization of these peoples. The coastline around Cagliari and its hinterland （southern Sardinia, Italy） were chosen as the subject, on the basis of the presence of both the sea and several ponds. The territory is noted as being home to both Neolithic and Eneolithic settlements. Among these the archaeological excavation of the village of Su Coddu/Canelles produced a large quantity of malacofauna. Data has been processed from part of the settlement that gave radiocarbon dating from the period between 3640 and 2900 cal. BC, and in which it was possible to carry out the level of sampling that was necessary to complete the research. In particular this interdisciplinary project, which aims to make an overall study of the settlement, the data relating to the geography of the area, the archaeological documentation, the fauna and shell artefacts will be extrapolated. Numerous methods are applied above all in reference to the marines and ponds resources. Additionally, the morphological anatomical-comparative analysis （in order to determine the typology of the faunal remains and to identify each individual species） and the technological analysis of the manufactured shells （so as to detect the selection and the transformation type of raw materials） are accomplished. The research has led to the identification of a settlement model in which agriculture formed the primary means of subsistence, that was complemented by the rearing of livestock, through hunting and gathering. The exploitation of marine and inland waters resources, as food source, have to be important because 99% of the faunal remains are shells. Different shell species are recognized, among those the Ostrea edulis provides the raw material to produce bevelled objects, which are documented inside the settlement in considerable number. Some plant species, typical of the lagoon ecosystem, were used for building and craft production.
文摘For the geological disposal of high level radioactive wastes, an excavation damaged zone （EDZ） having high hydraulic conductivity resulting from the development of fractures in the rock adjacent to the tunnels will be one of the potential pathways for radioactive contaminant transport. The potential pathways will be sealed by closure components, that is, a combination of tunnel plug, backfill and grout, the latter material being a clay-based mixture in consideration of the need for long-term stability of the seals. Clay-based grout is one of the effective candidate materials that can be used to interrupt the migration of radionuclides through an EDZ. Laboratory testing of clay-based grout using pulverized bentonite, with the objective of improvement in grout penetration into a rockmass, was conducted. The results showed that the pulverization of clay-based grout had a positive effect on filtration.
基金supported by the National Natural Science Foundation of China(Grant Nos.41271002,41430530)the State Key Laboratory of Loess and Quaternary Geology(Grant No.SKLLQG1101)+2 种基金the NIGLAS 1-3-5 Project(Grant No.NIGLAS2012135004)the State Key Laboratory of Lake Science and Environment(Grant No.2012SKL002)the China Postdoctoral Science Foundation(Grant Nos.2012M520061,2013T60567)
文摘The palaeolake evolution across the Tibetan Plateau and adjacent areas has been extensively studied, but the timing of late Pleistocene lake highstands remains controversial. Robust dating of lacustrine deposits is of importance in resolving this issue. This paper presents 14 C or optically stimulated luminescence(OSL) age estimates from two sets of late Quaternary lacustrine sequences in the Qaidam Basin and Tengger Desert(northeastern Tibetan Plateau). The updated dating results show:(1) the radiocarbon dating technique apparently underestimated the age of the strata of >30 ka BP in Qaidam Basin;(2) although OSL and 14 C dating agreed with each other for Holocene age samples in the Tengger Desert area, there was a significant offset in dating results of sediments older than ~30 ka BP, largely resulting from radiocarbon dating underestimation;(3) both cases imply that most of the published radiocarbon ages(e.g., older than ~30 ka BP) should be treated with caution and perhaps its geological implication should be revaluated; and(4) the high lake events on the Tibetan Plateau and adjacent areas, traditionally assigned to MIS 3a based on 14 C dating, are likely older than ~80 ka based on OSL chronology.
基金Supported by the National Basic Research Program(973 Program)of China(No.2007CB407205)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KSCX1-YW-09-13)+1 种基金the National Key Technology R&D Program of China during the 12th Five-Year Plan Period(No.2011BAD31B00)the National Major Science and Technology Program of China for Water Pollution Control and Treatment(No.009ZX07106-03-01)
文摘Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tracer technique in Mojiagou Basin located on the outskirts of Changchun in Northeast China. The calculated soft erosion rates in the study area were 1.99 and 1.85 mm year-1 using 137Cs and excess 210pb （210Pbex） measurements, respectively. Both fallout radionuclides showed a similar tendency at downslope sites. All measured sites have experienced net erosion during the past 50 to 100 years. 137Cs and 210Pbex measurements were useful to quantify soil erosion rates on field and small basin scales. At this rate of erosion, the current fertile topsoil layer would be entirely removed within 70 years.
基金supported by the Special Funds of Public Welfare of China (Grant No. GYHY201306061)the National Natural Science Foundation of China (Grant Nos. 41230421, 41105065 & 41275128)
文摘A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data on pollutant emissions during the accident, this study simulates the dispersion of nuclear pollutants. The source term of the nuclear leakage of radioactive material is designed using PM2.5 as the tracer of radioactive pollutants, and the study considers dry and wet deposition processes. A coupled-model system is constructed from the air-quality model Models-3/CMAQ and the Weather Research and Forecasting atmospheric model. The transport path and distribution of radioactive pollutants over long and short distances are simulated with different model horizontal resolutions of 30 and 4 km respectively. The long-distance simulation shows that, following the Fukushima nuclear accident, under the effect of westerly winds, radioactive pollutants are transported generally towards the eastern Pacific and reach the American continent after 5 days, but their concentration is only about 10-7 times the concentration near the Fukushima Nuclear Power Plant. The time required for pollutants to reach the United States is basically consistent with measurements made in California on March 18. Because the upper westerly wind is faster than the lower westerly wind, the distribution of pollutants tilts eastward in terms of its vertical structure. The short-distance （local） highresolution simulation indicates that strong winds and precipitation associated with a cyclone can accelerate the deposition, dif- fusion and transport of pollutions, and local cyclonic circulation can change the transport path of pollutants, even resulting in repeated effects of pollution in some areas. Pollutants disperse to southeastern Honshu, Japan, on March 14, 2011, agreeing well with the timing of local observations of increases in the absorbed dose rate. Results also show that radioactive pollutants from the Fukushima nuclear accident are mainly transported and diffuse eastward, resulting in a relatively short-term impact on the Japanese mainland even under the influence of the cyclone system. Therefore, in terms of atmospheric conditions, the location of the Fukusbima Nuclear Power Plant is appropriate and could serve as a reference to site selection and protection of other nuclear facilities.
