Promoting the coupling coordination development of port and its hinterland city environments is an important way to improve urban economic competitiveness.Based on relevant data of 13 coastal port cities in eastern Ch...Promoting the coupling coordination development of port and its hinterland city environments is an important way to improve urban economic competitiveness.Based on relevant data of 13 coastal port cities in eastern China from 2000 to 2018,this study explores the coupling coordination development of port and city environments and its impact on urban economic competitiveness by constructing the coupling coordination degree model and the panel threshold model.The research results show that:(1)In terms of the coupling coordination development of port and city environments,most coastal ports and their hinterland cities are in a state of moderate or serious disorder.Overall,the degree of coupling coordination of port and city environments needs to be further improved;(2)The coupling coordination degree of port and city environments has a significant impact on urban economic competitiveness,and this effect gradually increases with the development of the ports and the urban economy.Among the variables that impact the urban economic competitiveness,fixed assets investment and foreign trade are significant factors that can enhance urban economic competitiveness.(3)At present,there is a“U-shaped”relationship between the coupling coordination degree of port-city environments and the urban economic competitiveness.This relationship lies on the right side of the inflection point of the“U-shaped”curve.Therefore,following the concept of assigning priority to ecological development,expanding fixed assets investment and actively developing foreign trade can further enhance the urban economic competitiveness.展开更多
In the history, the main roles of inland rivers in Beilun Port City of Ningbo were desalination,blocking tides, shipping, and flood control. Nowadays, with the continuous spread and deepening ofurbanization, the ecolo...In the history, the main roles of inland rivers in Beilun Port City of Ningbo were desalination,blocking tides, shipping, and flood control. Nowadays, with the continuous spread and deepening ofurbanization, the ecological environment of river courses has been destroyed. In the past, remediationmeasures based on engineering and technology played a certain role, but can not “cure the root cause”. Itshould respect the historical evolution process of river courses, and highlight the ecological service functionand leisure tourism value of river courses from the coordination perspective of urban and rural ecologicalenvironment, economic industries, society and culture in the planning ideas of ecology, production, andlife integration. Four aspects of the measures are as below: protecting and repairing the ecological matrixof river courses;building green space system and maintaining flood control functions through the waternetwork;protecting cultural heritage along the rivers;developing waterfront leisure tourism scenic area.展开更多
Using the ‘theoretical hypothesis—empirical study—case verification' method, this paper studies the spatial distribution and differentiation of port & shipping service enterprises(PSSE), as well as the vari...Using the ‘theoretical hypothesis—empirical study—case verification' method, this paper studies the spatial distribution and differentiation of port & shipping service enterprises(PSSE), as well as the variation process and underlying mechanism in the Yangtze River Delta(YRD). First, through inductive and deductive reasoning, we propose the following hypothesis: the regional distribution of different types of PSSE would show different spatial agglomeration-decentralization tendency; and there would be distinct regional differentiation in the industrial structure of the enterprises. Second, based on data obtained from enterprises, empirical research is conducted using Gini coefficient and spatial interpolation simulation methods. Results show that: 1) The overall enterprise distribution is decentralized within a city. 2) Different types of enterprises show different spatial agglomeration-decentralization tendencies. At 3000 m×3000 m grid scale, there is an agglomeration tendency along seas and rivers in the spatial distribution of enterprises. Shanghai has been identified consistently as a hot spot. 3) There is significant regional differentiation in 12 port cities with respect to the industrial structures of enterprises. Finally, the transportization and the increase of shipping service demand, the globalization and the expansion of multinational corporate activities, the hierarchization and the cooperation among port cities as well as the decentralization and the behavioral difference between the central and local states can be seen as main driving mechanism of the spatial phenomenon.展开更多
agglomeration of the Yangtze Delta (UAYD), one of the most developed regions of China, has witnessed an increasing prevalence in building ecological cities when the ecological cities are pursued by many modern citie...agglomeration of the Yangtze Delta (UAYD), one of the most developed regions of China, has witnessed an increasing prevalence in building ecological cities when the ecological cities are pursued by many modern cities, and great achievements have been made in this regard. It is inevitable, however, that certain problems exist during the construction of ecological city, which include but not limited to non-harmonious development of urban complex ecosystem, and the difficulty in quantifying eco-city construction or incomplete quantification in assessing the con- structiori of present and future eco-city. Based on the analysis on social-economic conditions and regional conditions of the UAYD, this paper attempts to set up an index system of eco-cities combining with local characteristics, and to adopt the indices of eco-city, urban harmony, and eco-city colligate to evaluate the ecological level, urban harmonious development and eco-city construction of cities within the UAYD. Results indicate that among 15 cities in UAYD, Suzhou City ranks the highest in terms of eco-city construction, whereas Nantong ranks relatively lower; sustainable eco-city construction is possible only when cities are developed in every respect of harmony.展开更多
Taking the practical experience of Lianjie Town, Weiyuan County for example, this paper analyzed regional characteristics of the low hilly areas in Sichuan and interaction mechanism of "industrialization and urba...Taking the practical experience of Lianjie Town, Weiyuan County for example, this paper analyzed regional characteristics of the low hilly areas in Sichuan and interaction mechanism of "industrialization and urbanization", explored the path for the interaction between industrialization and urbanization from 5 perspectives, namely accelerating industrial upgrading, optimizing industrial structure, breaking through the dual system, industry back-feeding town, and protecting ecological background.展开更多
The Port of Durban is one of the largest ports in the Southern Hemisphere and is the main port for the Southern African region. However, the port is reaching its capacity limit and it is apparent that for South Africa...The Port of Durban is one of the largest ports in the Southern Hemisphere and is the main port for the Southern African region. However, the port is reaching its capacity limit and it is apparent that for South Africa's economic growth this port needs to expand. In order to expand the port needs to not only expand its waterside infrastructure but it would need to provide new logistics corridors though the city of Durban. The city of Durban has completely surrounded the port making expansion options difficult and intertwined with the planning of the city. This paper examines the various options and timelines for port expansion as well as the issues from the city perspective. Areas of possible conflict in this process revolve around traffic capacity and related road/rail infrastructure, environmental issues, social and economic impacts.展开更多
Seattle Located on a neck of land between the Elliott Bay (the Puget Sound) and Lake Washington, Seattle is a major city of Washington State and the largest metropolis of the Pacific Northwest in the USA. It is a port...Seattle Located on a neck of land between the Elliott Bay (the Puget Sound) and Lake Washington, Seattle is a major city of Washington State and the largest metropolis of the Pacific Northwest in the USA. It is a port of entry and gateway to Asia and Alaska. The city has an area of 84 square miles and a population of about 516,000 (1992), with a density of 10,879 per Square mile.展开更多
Manzhouli is the largest land port city on the Sino-Russia border,transit cargo through the land port amount -ed to 5.95million tons,transit tour ists were 304500in 2000.It stands at the joint place of China,Mongolia ...Manzhouli is the largest land port city on the Sino-Russia border,transit cargo through the land port amount -ed to 5.95million tons,transit tour ists were 304500in 2000.It stands at the joint place of China,Mongolia an d Russi-a,faces to Siberia area of Russia,re ceives direct support from the North east China and Bohai Sea Rim Area,and possess-es priorities in geographical location,land port infrastructure,wate r resources,coal resources,touris t resources and great potentiality in economic coop eration with Russia.The future urban function is a key port on the First Eurasia Continen-tal Bridge.Manzhouli Port will keep its first place between China and Russia land transport,and it is forecasted that the transit amount through Manzhouli Port will go up to 10million tons in 2005and 20million tons in 2010.It will be construct-ed to be a trade center of the peripheral area extending to Russia and Mongolia,a key export-oriented processing industri-al zone supported by industries such as export processing industries,export agriculture,trade services,t echnology trad-ing and the other service industries.It keeps being a well-known touring city for trade,shopping,sightseeing,vocation,local food,recreation and cultural events.To build Manzhouli Export Pr ocessing Industry Zone will improve city econom-ic structure,and the main sectors are organic food processing,livestock products processing,garment and f urniture indus-try.Moreover,Manzhouli Export Pro cessing Industry Zone will eventually be upgraded to be a border free trad e zone.The city functional transition will inevitably affect urban spatial restructure and its expansion.The city space transforma-tion will develop as such:one develo pment axis of No.301highway paralle ling with Bin -Zhou(Harbin -Manzhouli)rail-way which cuts through central part o f Manzhouli City,and links Zhalainuoer District with central city;thre e urban units including central city,Zhalainuoer District and Manzhouli Interchange Trade Zone;cohesion with Aoerjin a nd Cuogang pastures;regional dual-nuclei str ucture of Hailaer City and Manhzouli City;and the Manzhouli-Zabaykalsk Free Trade Zone.展开更多
Lince port cities are the first new force of China's economy to outside world, they have been developing rapidly under the open policy In this article, Zhejiang's coast port cities are taken as research subjec...Lince port cities are the first new force of China's economy to outside world, they have been developing rapidly under the open policy In this article, Zhejiang's coast port cities are taken as research subject Through intensive analysis of a great number of data which had been obtained during onthespot investigations, the regional conditions, superior and inferior conditions for development of Zhejiang's coast port cities are systematically surveyed, the development of their overall distribution trait, internal structure morphology and outer morphology is examined and the development trend of port city allocation is identified which provide theoretical basis for the further development of port cities展开更多
Zhangjiagang, located on the lower reaches of the Yangtze River and an important military town in ancient times, was previously under the. jurisdiction of Shazhou County. It became Zhangjiagang City in 1986, named aft...Zhangjiagang, located on the lower reaches of the Yangtze River and an important military town in ancient times, was previously under the. jurisdiction of Shazhou County. It became Zhangjiagang City in 1986, named after Zhangjiagang, a natural port in the area. With fertile soil, a good climate and sufficient rainfall, Zhangjiagang is a production base for high yield grain and good quality cotton. In addition, it is renowned for its variety of river food, chicken, peaches, grapes, wine, water melons and tea.展开更多
The present work focuses on the volcanic basement rock geochemistry of Mount Makabaï(MarouaCameroon city)in relation to groundwater geochemistry.Investigations were centered on an approach involving an associatio...The present work focuses on the volcanic basement rock geochemistry of Mount Makabaï(MarouaCameroon city)in relation to groundwater geochemistry.Investigations were centered on an approach involving an association of several methods such as geological cartography,hydrogeology,and geochemistry.Three rock samples,four disturbed soil samples,three undisturbed soil samples,and 20 samples of groundwater in 10 wells were collected during fieldwork and prepared for laboratory analyses.Bedrocks exhibit porphyritic,aphyric,and subaphiric textures.The phenocryst phases are mainly olivine,clinopyroxene,and plagioclase.Based on whole rock major element chemical compositions,the Makabaï samples,plotted on Na_(2)O+K_(2)O versus SiO_(2)diagram,are mugearite,hawaiite,and basalt.The ratio of(MgO+CaO)/(Na_(2)O+K_(2)O)exceeds unity and shows dominance of alkaline Earth metals(MgO:2.99-4.48%;CaO:6.19-9.80%)relatively to alkali metals(Na_(2)O:2.27-4.46%;K_(2)O:2.09-2.51%).Exchangeable base contents are high,mostly represented by Ca and Mg,whose contents vary from 14.6 to 35.28 cmol(+)kg^(-1)and from 3.28 to9.48 cmol(+)kg^(-1)respectively.The CECclayis likewise high,fluctuating between 116.80 and181.38 cmol(+)kg^(-1),values in line with the presence of 2:1 clay minerals represented in the study area by montmorillonite.In the water samples,the Ca2+and Na+contents are generally higher than K^(+)and Mg^(2+),reflecting the relative abundance of Na_(2)O and CaO oxides to K_(2)O and MgO oxides in rocks where different waters were sampled.The waters of Makabaï are acidic to neutral(6.3≤pH≤7.4)and weakly to highly mineralized(110.0≤EC≤1190.0μS/cm).Hydro-geochemical classification by using the Piper diagram revealed two water types:(1)CaMg-HCO_(3)(40%)and(2)CaMg-Cl or CaMg-SO4(60%).The average content of ions in all the analyzed samples was HCO_(3)^(-)>>NO_(3)^(-)>SO_(4)^(2-)>Cl-for anions and Ca^(2+)>>Mg^(2+)>Na^(+)>K^(+)for cations.Major mechanisms governing ionic constituents of groundwater in the study area are water-rock interactions,silicate weathering,and ion exchange.展开更多
The aim of this paper is to obtain relevant sets of collision cross sections of the parent ions in low pressure discharges in argon, oxygen, and nitrogen, i.e., Ar+ in Ar, O2+ in O2 and N2+ in N2. These ion data ar...The aim of this paper is to obtain relevant sets of collision cross sections of the parent ions in low pressure discharges in argon, oxygen, and nitrogen, i.e., Ar+ in Ar, O2+ in O2 and N2+ in N2. These ion data are first discussed and then validated from comparisons between the calculated transport coefficients and those measured in the literature. The elastic momentum transfer collision cross sections are determined from a semi-classical approximation for the phase shift calculation based on a 12-6-4 inter-particle potential while ion transport coefficients are determined versus the reduced electric field from Monte Carlo simulations.展开更多
The Saigon River is located in southern Vietnam with headwaters starting in southeastern Cambodia. The river flows southeast for about 225 km to the South China Sea. Most readers of Vietnam’s history know about the A...The Saigon River is located in southern Vietnam with headwaters starting in southeastern Cambodia. The river flows southeast for about 225 km to the South China Sea. Most readers of Vietnam’s history know about the American-Vietnam War (1965-1973). However, centuries before that time, Vietnam fought with the Chinese, the Khmers, the Chams and the Mongols. The history of Vietnam begins in the Red River Delta, where farmers first cultivated rice. A millenia of struggle against the Chinese then followed. The Saigon River Valley was the pathway used by the North Vietnamese Army (NVA) to get from the Ho Chi Minh Trail in Cambodia to Saigon during the 1968 Tet Offensive. The NVA dug Cu Chi and Iron Triangle soil tunnels near Cu Chi in the Old Alluvium terrace to hide from American Forces and Air Force bombers. In 1962, the Tan Son Nhut Air Force base on the northern edge of Saigon received the first shipments of Agent Blue, the arsenic based herbicide, used to destroy the rice crop. The most dioxin TCDD and arsenic contaminated site in Vietnam was Bien Hoa Air Force base on the Saigon River just 30 km northeast east of Ho Chi Minh City. The adjacent Bien Hoa City has a population of over 800,000. The Port of Ho Chi Minh City is the most significant river port in Vietnam and Southeast Asia. The river is navigable by ships which draft up to 9 m. Vietnam only became a united country in the 19th century. Its independence was soon affected by French colonialism and then the destructive American intervention in the Vietnam War. The Vietnam War Archive no. 2 in Ho Chi Minh City houses residual correspondence between the Republic of Vietnam (RV) President Diem’s administration and US President Kennedy’s administration related to the Khai Huang program (hamlet strategy). In addition, the archive contains some of the tactical herbicide spray records of the RV military for the Mekong Delta. The primary objective this study is to document the role that the Saigon River Valley played, in modern warfare. The Saigon River Valley was used as a navigation, trade, invasion, liberation and unification pathway. The Vietnamese people have survived centuries of stormy, troubled times and their power of character has served them well.展开更多
基金This research is supported by Hunan Provincial Natural Science Foundation of China(Grant No.2021JJ30304)the General Topics of Hunan Social Science Achievement Evaluation Committee of China(Grant No.XSP22YBC366)the Key Scientific Research Project of Hunan Provincial Department of Education of China(Grant No.21B0592).
文摘Promoting the coupling coordination development of port and its hinterland city environments is an important way to improve urban economic competitiveness.Based on relevant data of 13 coastal port cities in eastern China from 2000 to 2018,this study explores the coupling coordination development of port and city environments and its impact on urban economic competitiveness by constructing the coupling coordination degree model and the panel threshold model.The research results show that:(1)In terms of the coupling coordination development of port and city environments,most coastal ports and their hinterland cities are in a state of moderate or serious disorder.Overall,the degree of coupling coordination of port and city environments needs to be further improved;(2)The coupling coordination degree of port and city environments has a significant impact on urban economic competitiveness,and this effect gradually increases with the development of the ports and the urban economy.Among the variables that impact the urban economic competitiveness,fixed assets investment and foreign trade are significant factors that can enhance urban economic competitiveness.(3)At present,there is a“U-shaped”relationship between the coupling coordination degree of port-city environments and the urban economic competitiveness.This relationship lies on the right side of the inflection point of the“U-shaped”curve.Therefore,following the concept of assigning priority to ecological development,expanding fixed assets investment and actively developing foreign trade can further enhance the urban economic competitiveness.
文摘In the history, the main roles of inland rivers in Beilun Port City of Ningbo were desalination,blocking tides, shipping, and flood control. Nowadays, with the continuous spread and deepening ofurbanization, the ecological environment of river courses has been destroyed. In the past, remediationmeasures based on engineering and technology played a certain role, but can not “cure the root cause”. Itshould respect the historical evolution process of river courses, and highlight the ecological service functionand leisure tourism value of river courses from the coordination perspective of urban and rural ecologicalenvironment, economic industries, society and culture in the planning ideas of ecology, production, andlife integration. Four aspects of the measures are as below: protecting and repairing the ecological matrixof river courses;building green space system and maintaining flood control functions through the waternetwork;protecting cultural heritage along the rivers;developing waterfront leisure tourism scenic area.
基金Under the auspices of National Natural Science Foundation of China(No.41771139,41671132,41801111)Natural Science Foundation of Jiangsu Province(No.BK20171516)Natural Science Foundation of Zhejiang Province(No.LY18D010004)
文摘Using the ‘theoretical hypothesis—empirical study—case verification' method, this paper studies the spatial distribution and differentiation of port & shipping service enterprises(PSSE), as well as the variation process and underlying mechanism in the Yangtze River Delta(YRD). First, through inductive and deductive reasoning, we propose the following hypothesis: the regional distribution of different types of PSSE would show different spatial agglomeration-decentralization tendency; and there would be distinct regional differentiation in the industrial structure of the enterprises. Second, based on data obtained from enterprises, empirical research is conducted using Gini coefficient and spatial interpolation simulation methods. Results show that: 1) The overall enterprise distribution is decentralized within a city. 2) Different types of enterprises show different spatial agglomeration-decentralization tendencies. At 3000 m×3000 m grid scale, there is an agglomeration tendency along seas and rivers in the spatial distribution of enterprises. Shanghai has been identified consistently as a hot spot. 3) There is significant regional differentiation in 12 port cities with respect to the industrial structures of enterprises. Finally, the transportization and the increase of shipping service demand, the globalization and the expansion of multinational corporate activities, the hierarchization and the cooperation among port cities as well as the decentralization and the behavioral difference between the central and local states can be seen as main driving mechanism of the spatial phenomenon.
文摘agglomeration of the Yangtze Delta (UAYD), one of the most developed regions of China, has witnessed an increasing prevalence in building ecological cities when the ecological cities are pursued by many modern cities, and great achievements have been made in this regard. It is inevitable, however, that certain problems exist during the construction of ecological city, which include but not limited to non-harmonious development of urban complex ecosystem, and the difficulty in quantifying eco-city construction or incomplete quantification in assessing the con- structiori of present and future eco-city. Based on the analysis on social-economic conditions and regional conditions of the UAYD, this paper attempts to set up an index system of eco-cities combining with local characteristics, and to adopt the indices of eco-city, urban harmony, and eco-city colligate to evaluate the ecological level, urban harmonious development and eco-city construction of cities within the UAYD. Results indicate that among 15 cities in UAYD, Suzhou City ranks the highest in terms of eco-city construction, whereas Nantong ranks relatively lower; sustainable eco-city construction is possible only when cities are developed in every respect of harmony.
文摘Taking the practical experience of Lianjie Town, Weiyuan County for example, this paper analyzed regional characteristics of the low hilly areas in Sichuan and interaction mechanism of "industrialization and urbanization", explored the path for the interaction between industrialization and urbanization from 5 perspectives, namely accelerating industrial upgrading, optimizing industrial structure, breaking through the dual system, industry back-feeding town, and protecting ecological background.
文摘The Port of Durban is one of the largest ports in the Southern Hemisphere and is the main port for the Southern African region. However, the port is reaching its capacity limit and it is apparent that for South Africa's economic growth this port needs to expand. In order to expand the port needs to not only expand its waterside infrastructure but it would need to provide new logistics corridors though the city of Durban. The city of Durban has completely surrounded the port making expansion options difficult and intertwined with the planning of the city. This paper examines the various options and timelines for port expansion as well as the issues from the city perspective. Areas of possible conflict in this process revolve around traffic capacity and related road/rail infrastructure, environmental issues, social and economic impacts.
文摘Seattle Located on a neck of land between the Elliott Bay (the Puget Sound) and Lake Washington, Seattle is a major city of Washington State and the largest metropolis of the Pacific Northwest in the USA. It is a port of entry and gateway to Asia and Alaska. The city has an area of 84 square miles and a population of about 516,000 (1992), with a density of 10,879 per Square mile.
文摘Manzhouli is the largest land port city on the Sino-Russia border,transit cargo through the land port amount -ed to 5.95million tons,transit tour ists were 304500in 2000.It stands at the joint place of China,Mongolia an d Russi-a,faces to Siberia area of Russia,re ceives direct support from the North east China and Bohai Sea Rim Area,and possess-es priorities in geographical location,land port infrastructure,wate r resources,coal resources,touris t resources and great potentiality in economic coop eration with Russia.The future urban function is a key port on the First Eurasia Continen-tal Bridge.Manzhouli Port will keep its first place between China and Russia land transport,and it is forecasted that the transit amount through Manzhouli Port will go up to 10million tons in 2005and 20million tons in 2010.It will be construct-ed to be a trade center of the peripheral area extending to Russia and Mongolia,a key export-oriented processing industri-al zone supported by industries such as export processing industries,export agriculture,trade services,t echnology trad-ing and the other service industries.It keeps being a well-known touring city for trade,shopping,sightseeing,vocation,local food,recreation and cultural events.To build Manzhouli Export Pr ocessing Industry Zone will improve city econom-ic structure,and the main sectors are organic food processing,livestock products processing,garment and f urniture indus-try.Moreover,Manzhouli Export Pro cessing Industry Zone will eventually be upgraded to be a border free trad e zone.The city functional transition will inevitably affect urban spatial restructure and its expansion.The city space transforma-tion will develop as such:one develo pment axis of No.301highway paralle ling with Bin -Zhou(Harbin -Manzhouli)rail-way which cuts through central part o f Manzhouli City,and links Zhalainuoer District with central city;thre e urban units including central city,Zhalainuoer District and Manzhouli Interchange Trade Zone;cohesion with Aoerjin a nd Cuogang pastures;regional dual-nuclei str ucture of Hailaer City and Manhzouli City;and the Manzhouli-Zabaykalsk Free Trade Zone.
文摘Lince port cities are the first new force of China's economy to outside world, they have been developing rapidly under the open policy In this article, Zhejiang's coast port cities are taken as research subject Through intensive analysis of a great number of data which had been obtained during onthespot investigations, the regional conditions, superior and inferior conditions for development of Zhejiang's coast port cities are systematically surveyed, the development of their overall distribution trait, internal structure morphology and outer morphology is examined and the development trend of port city allocation is identified which provide theoretical basis for the further development of port cities
文摘Zhangjiagang, located on the lower reaches of the Yangtze River and an important military town in ancient times, was previously under the. jurisdiction of Shazhou County. It became Zhangjiagang City in 1986, named after Zhangjiagang, a natural port in the area. With fertile soil, a good climate and sufficient rainfall, Zhangjiagang is a production base for high yield grain and good quality cotton. In addition, it is renowned for its variety of river food, chicken, peaches, grapes, wine, water melons and tea.
文摘The present work focuses on the volcanic basement rock geochemistry of Mount Makabaï(MarouaCameroon city)in relation to groundwater geochemistry.Investigations were centered on an approach involving an association of several methods such as geological cartography,hydrogeology,and geochemistry.Three rock samples,four disturbed soil samples,three undisturbed soil samples,and 20 samples of groundwater in 10 wells were collected during fieldwork and prepared for laboratory analyses.Bedrocks exhibit porphyritic,aphyric,and subaphiric textures.The phenocryst phases are mainly olivine,clinopyroxene,and plagioclase.Based on whole rock major element chemical compositions,the Makabaï samples,plotted on Na_(2)O+K_(2)O versus SiO_(2)diagram,are mugearite,hawaiite,and basalt.The ratio of(MgO+CaO)/(Na_(2)O+K_(2)O)exceeds unity and shows dominance of alkaline Earth metals(MgO:2.99-4.48%;CaO:6.19-9.80%)relatively to alkali metals(Na_(2)O:2.27-4.46%;K_(2)O:2.09-2.51%).Exchangeable base contents are high,mostly represented by Ca and Mg,whose contents vary from 14.6 to 35.28 cmol(+)kg^(-1)and from 3.28 to9.48 cmol(+)kg^(-1)respectively.The CECclayis likewise high,fluctuating between 116.80 and181.38 cmol(+)kg^(-1),values in line with the presence of 2:1 clay minerals represented in the study area by montmorillonite.In the water samples,the Ca2+and Na+contents are generally higher than K^(+)and Mg^(2+),reflecting the relative abundance of Na_(2)O and CaO oxides to K_(2)O and MgO oxides in rocks where different waters were sampled.The waters of Makabaï are acidic to neutral(6.3≤pH≤7.4)and weakly to highly mineralized(110.0≤EC≤1190.0μS/cm).Hydro-geochemical classification by using the Piper diagram revealed two water types:(1)CaMg-HCO_(3)(40%)and(2)CaMg-Cl or CaMg-SO4(60%).The average content of ions in all the analyzed samples was HCO_(3)^(-)>>NO_(3)^(-)>SO_(4)^(2-)>Cl-for anions and Ca^(2+)>>Mg^(2+)>Na^(+)>K^(+)for cations.Major mechanisms governing ionic constituents of groundwater in the study area are water-rock interactions,silicate weathering,and ion exchange.
文摘The aim of this paper is to obtain relevant sets of collision cross sections of the parent ions in low pressure discharges in argon, oxygen, and nitrogen, i.e., Ar+ in Ar, O2+ in O2 and N2+ in N2. These ion data are first discussed and then validated from comparisons between the calculated transport coefficients and those measured in the literature. The elastic momentum transfer collision cross sections are determined from a semi-classical approximation for the phase shift calculation based on a 12-6-4 inter-particle potential while ion transport coefficients are determined versus the reduced electric field from Monte Carlo simulations.
文摘The Saigon River is located in southern Vietnam with headwaters starting in southeastern Cambodia. The river flows southeast for about 225 km to the South China Sea. Most readers of Vietnam’s history know about the American-Vietnam War (1965-1973). However, centuries before that time, Vietnam fought with the Chinese, the Khmers, the Chams and the Mongols. The history of Vietnam begins in the Red River Delta, where farmers first cultivated rice. A millenia of struggle against the Chinese then followed. The Saigon River Valley was the pathway used by the North Vietnamese Army (NVA) to get from the Ho Chi Minh Trail in Cambodia to Saigon during the 1968 Tet Offensive. The NVA dug Cu Chi and Iron Triangle soil tunnels near Cu Chi in the Old Alluvium terrace to hide from American Forces and Air Force bombers. In 1962, the Tan Son Nhut Air Force base on the northern edge of Saigon received the first shipments of Agent Blue, the arsenic based herbicide, used to destroy the rice crop. The most dioxin TCDD and arsenic contaminated site in Vietnam was Bien Hoa Air Force base on the Saigon River just 30 km northeast east of Ho Chi Minh City. The adjacent Bien Hoa City has a population of over 800,000. The Port of Ho Chi Minh City is the most significant river port in Vietnam and Southeast Asia. The river is navigable by ships which draft up to 9 m. Vietnam only became a united country in the 19th century. Its independence was soon affected by French colonialism and then the destructive American intervention in the Vietnam War. The Vietnam War Archive no. 2 in Ho Chi Minh City houses residual correspondence between the Republic of Vietnam (RV) President Diem’s administration and US President Kennedy’s administration related to the Khai Huang program (hamlet strategy). In addition, the archive contains some of the tactical herbicide spray records of the RV military for the Mekong Delta. The primary objective this study is to document the role that the Saigon River Valley played, in modern warfare. The Saigon River Valley was used as a navigation, trade, invasion, liberation and unification pathway. The Vietnamese people have survived centuries of stormy, troubled times and their power of character has served them well.