United States Secret War in Laos: Long-Term Environmental and Human Health Impacts of the Use of Chemical Weapons

In 1959, the United States Central Intelligence Agency (CIA) operation, against the Pathet Lao insurgences and Viet Mien military troops and supply route, began. The Ho Chi Minh Trail was developed after the North Vietnam government and military decided to reunify South and North Vietnam. The People’s Army of Vietnam (PAVN) then connected the old trails leading from North Vietnam panhandle southward into eastern Laos, Cambodia and South Vietnam. Starting from Hanoi, the primary trail turned southwest into Laos and eastern Cambodia before branching into South Vietnam. Beginning in 1960s, the volume of traffic on the network of trails expanded significantly, but it still took more than a month’s march, by foot and bicycle, to travel from North to South Vietnam. Ho Chi Minh Trail traffic was impacted by repeatedly by Royal Laotian Air Force (RLAF), which was supported by US Air Force tactical herbicide spraying (Operation Ranch Hand program), and US Air Force bombing runs. By the late 1960s, the trail was improved and could accommodate heavy trucks in some sections and was used to supply the annual needs of over one hundred thousand regular PAVN troops active in South Vietnam. By 1974, the trail was a well-marked series of jungle roads (some of them paved) with underground support facilities such as hospitals, fuel-storage tanks, and supply caches with weapons. The Ho Chi Minh Trail was the major supply route for PAVN forces that overran Republic of Vietnam (RV) forces in 1975 and unified Vietnam. The primary objective of this paper is to determine the environmental and human health impacts of RLAF and US Air Force secret spraying of tactical herbicides on Ho Chi Minh Trail in Laos.

Review and Analysis: United States Cluster Munitions and Unexploded Ordnance Left in Laos after the Second Indochina War

Cluster munitions release dozens of smaller bomblets that rain deadly ammunition on armored tanks, vegetation and troops, effectively striking broad areas of war zone landscapes in one launch. However, only about 60% of bomblets detonate immediately and those that fail to detonate fall to the ground and can lie dormant for years. The legacy of cluster munitions in Laos from the Second Indochina War is unexploded bomblets across the landscape that unexpectedly detonate years later, injuring and killing children, farmers, and other civilians long after the war is over. In Laos, the United States (US) military operation against the Ho Chi Minh Trail, a network of foot and bicycle paths, waterways, and truck routes along the Laos, Cambodia and Vietnam borders linking North and South Vietnam began in 1959. By the 1960s, as the war escalated, trail traffic was interdicted frequently by CIA and US Air Force using tactical herbicide spraying to defoliate dense vegetation and bombing to disrupt supplies and North Vietnamese troops dispersed along the 16,000-kilometer trail. Unexploded ordinance (UXO), including cluster munitions, from U.S. bombings continued in recent years to detonate, kill, maim and injure Laotians and render agricultural lands too hazardous to cultivate. The primary objectives of this study are to document: 1) the long-term consequences and impacts of the US Air Force bombing of Laos during the Second Indochina War (1959 to 1973);2) the United States removal of unexploded ordnance and cluster munitions;and 3) worldwide relief efforts to help the Laotians maimed by unexploded ordnance and cluster munitions.

New species and record of Bactrocera Macquart(Diptera:Tephritidae) from China and Laos

A new species, Bactrocera （Zeugodacus） gansuica Chen, Han et Zhou sp. nov., is discovered from China, and B （Z.） vultus （Hardy, 1973） is recorded for the first time in Laos. These two species are here described and illustrated.

GIS based land suitability assessment along Laos-China border

Assessment of the forest land use change and proposed land suitability for tea for the area along Laos – China Border were the main purpose of this research paper. An integrated GIS-based analysis system （IGAS）, supporting assessment of forest land-use and land suitability for the study area where along Laos-China border was developed. Multi criteria analysis and system dynamics techniques were used to assess forest land use and land suitability and to forecast potential land-use for tea. The total study area is estimated at 10 325.07 km2 according to the field data collection and data analysis. The area of current forest cover decreased rapidly from 6337.33 km2 （61.38%） in 1992 to 5106.28 km2 （49.46%） in 2002 in the study area. The current forest was mainly trans-ferred to potential forest and permanent agriculture especially to rubber plantation areas even in the National Conservation Biodiversity Conser-vation Areas. The main causes of forest land use change are poverty. In order to address the problems, land suitability classification for tea was developed based on the multi-criteria. And finally two options of land suitability classification for tea for the study areas were developed.

Visit China-Laos Year

Visit China-Laos Year 2019 was launched on January 25 in Vientiane, the capital of Laos.

Zircon U-Pb age,trace element and Hf isotope composition of Sepon Au-Cu deposit, Laos:tectonic and metallogenic implications

The Truong Son Fold Belt,located at the northeastern margin of the Indochina Block,is considered to be tectonically linked to the subduction of the Paleotethys Ocean and subsequent collision.Sepon is one of the most important super large deposits of the Truong Son Fold Belt.Our LA-ICP-MS zircon U-Pb dating results show that granodiorite porphyry samples from the Sepon deposit have ages of 302.1-4-2.9 Ma, which is a crucial phase for magmatic-tectonical activities from the Late Carboniferous to Early Permian and has avital influence on the mineralization of copper and gold.Zircon from granodiorite porphyry yields εHf (t)values of 4.32 to 9.64,and TDM2 has an average age of 914 Ma,suggesting that the source of the granodiorite porphyry in the region were mainly mantle components but underwent mixing and contamination of crust materials.The Ce^4+/Ce^3+ value of zircon in the granodiorite porphyry varys greatly from 2.4 to 1438.29,which shows magma mixing might occur.Considering the characteristics of trace elements in the zircon and the whole rock geochemical characteristics of intrusion rocks as well as the characteristics of regional volcanic-sedimentary association,it is indicated that the tectonic setting may be the continental arc environment.The Sepon Au-Cu deposit is derived from emplacement of calc-alkaline intermediate-acid magma with coming from deep sources in the subduction process of the Paleotethys Ocean,forming porphyry Mo-Cu,skam Cu-Au mineralization and a hydrothermal sedimentary-hosted Au mineralization in the wall rocks.

The characteristics, formation and exploration progress of the potash deposits on the Khorat Plateau, Thailand and Laos, Southeast Asia

The giant potash deposit on the Khorat Plateau is one of the most promising targets for exploitation of potassium salts.So far,many researches and geologic survey have been conducted on the giant potash deposits.Hence,it is necessary to make an overall review on the potash deposits.The potash deposit on the Khorat Plateau was formed during the Middle to Late Cretaceous,during which seawater was enriched in Ca2+and depleted in SO42-compared with those of modern seawater.In addition to seawater,continental water and hydrothermal fluids could have affected the evaporite basins.The seawater was probably derived from Tethys ocean,and the brine should have evaporated to some extent before entering into the basin systems based on the evidence of absence of carbonates and unproportionate sulphate compared with chloride salts.The paleo-climate during Middle to Late Cretaceous was characterized as high temperature and extremely arid environment,which is favourable for deposition of potassium-magnesium saline minerals.The major saline minerals are of anhydrite,halite,carnallite,sylvite and,tachyhydrite,with trace amounts of borates.The resources of the potash deposit on the Khorat Plateau could be approximately as much as 400×109 t of carnallite and 7×109 t of sylvite.The evaporite sequences have been deformed and altered by postdepositinal processes,including tectonic movements and chemical alteration.Salt domes were formed in the postdepositional processes.Based on the analyses of geophysical surveys and drilling projects,high-quality sylvinite ores are commonly found at the flanks of those salt domes due to incongruent dissolution of carnallite.The furure potential prospecting areas for the highquality sylvinite ores would be on the edges of the Khorat Plateau.

Petrogenesis of Middle Triassic andesite in Sayaburi area, Laos: Constraints from whole-rock geochemistry, zircon U-Pb geochronology, and Sr-Nd isotopes

Despite the presence of a large area of andesite in the Sayaburi Province of Laos, it has received very little attention. Based on a combination of detailed field investigations, geochronology and geochemical analysis, this study aims to explore the geochemical, Sr-Nd isotopic, and source rock characteristics, as well as the genesis and tectonic setting of the andesite in this region. In the Sayaburi Province, the andesite zircon U-Pb age is(241.2±1.2) Ma. The andesite rock is classified in the metaluminous-weak peraluminous calc-alkaline series. The light rare-earth elements(LREEs) are enriched and characterized by clear fractionation, whereas heavy rare-earth elements(HREEs) are relatively depleted and have no signs of fractionation. The average δEu is 0.96 with weak-or-no Eu anomalies. It is enriched in large ion lithophile elements such as Rb and K, while depleted in high field-strength elements such as Nb, Ta, P and Ti. For andesites in the Sayaburi Province, the(87Rb/86Sr)t value ranges in 0.702849-0.704687, the εNd(t) value is between 3.53 and 4.77, the tDM(t) value ranges in 633-835 Ma, and the tDM2(t) ranges in 625–724 Ma. The results based on the synthesis of petrology, geochemistry, and regional tectonic background studies show that 1) the andesitic magma source in the study area is an enriched mantle, which is modified by subduction zone fluids;2) the geotectonic background environment of the andesite in Sayaburi area is the continental island arc environment and related to the tectonic evolution of Jinghong–Nan–Uttaradit back-arc basin, which reflects that the magmatic source is enriched with a mantle wedge component modified by a subduction zone fluid(or melt).

A One-Health Sampling Strategy to Explore the Dissemination and Relationship Between Colistin Resistance in Human,Animal,and Environmental Sectors in Laos

This study was designed to investigate the molecular epidemiology of mobile colistin resistance(mcr)using a"One-Health"approach in Laos and to predict whether any dominant plasmid backbone and/or strain type influences the dissemination of mcr.We collected 673 samples from humans(rectal normal flora),poultry,and the environment(water,flies,birds,etc.)in Vientiane,Lao People’s Democratic Republic(Laos),from May to September 2018.A total of 238 Escherichia coli(E.coli)isolated from nonduplicative samples,consisting of 98 MCR-positive E.coli(MCRPEC)("mcr"denotes the gene encoding mobile colistin resistance,and"MCR"denotes the subsequent protein encoded by mcr)and 140 MCRnegative E.coli(MCRNEC),were characterized by phenotype and Illumina sequencing.A subset of MCRPEC was selected for Min ION sequencing,conjugation assay,plasmid stability,and growth kinetics in vitro.The prevalence of MCRPEC was found to be 14.6%(98/673),with the highest prevalence in human rectal swabs(45.9%(45/98),p<0.0001,odds ratio(OR):0.125,95% confidence interval(CI):0.077-0.202).The percentages of MCRPEC from other samples were 14.3%(2/14)in dog feces,12.0%(24/200)in flies,11.0%(11/100)in chicken meat,8.9%(8/90)in chicken cloacal,8.0%(4/50)in chicken caeca,and 7.5%(4/53)in wastewater.MCRPEC was significantly more resistant to co-amoxiclav,sulfamethoxazoletrimethoprim,levofloxacin,ciprofloxacin,and gentamicin than MCRNEC(p<0.05).Genomic analysis revealed the distribution of MCRPEC among diverse clonal types.The putative plasmid Inc types associated with mcr-1 were Inc X4,Inc HI2,Inc P1,Inc I2,and Inc FIA,and those associated with mcr-3 were Inc FII,Inc FIA,Inc FIB,Inc P1,and Inc R.Recovery of highly similar plasmids from both flies and other sampling sectors implied the role of flies in the dissemination of mcr-1.mcr-positive plasmids were shown to be conjugative,and a significantly high transfer rate into a hypervirulent clone ST1193 was observed.Plasmids containing mcr irrespective of Inc type were highly stable and invariably did not exert a fitness effect upon introduction into a new host.These findings signify the urgent need for a standard infection control program to radically decontaminate the source of resistance.

Geochronology and petrogeochemistry of Late Permian volcanic rocks in the B.Xiengnou area,Northwestern Laos:Petrogenesis and tectonic significance

The Nan Suture and Sukhothai Arc Terrane are products of the eastward subduction of the Paleotethyan Ocean during the Late Carboniferous to Triassic.However,their footprints in northwestern Laos are poorly constrained.New geochronological and geochemical data presented in this study demonstrate a Late Permian origin for the andesitic rocks in the B.Xiengnou area rather than Late Triassic.The breccia-bearing andesitic tuff in the B.On ultramafic complex yield a zircon U-Pb age of 260±1.4 Ma,geochemically displaying a MORB-like signature.The andesitic tuff in the B.Kiophoulan-B.Houayhak belt gave the U-Pb age of 254±1.3 Ma,with arc-like geochemical affinity.By combining geochronological and geochemical data from the Nan Suture and Sukhothai Arc Terrane,the authors suggest that the andesitic rocks in the B.On ultramafic complex formed in a back-arc basin background,which connected the Jinghong and Nan back-arc basin during the Permian;while the andesitic tuff in the B.Kiophoulan-B.Houayhak belt erupted in the Sukhothai continental arc setting.

Development of land valuation approach based on hedonic model--A case study of Vientiane capital city Laos

The aim of this study is to identify the variables affecting land value. Examined land was selected from the village in Vientiane capital city Laos. Data was collected from 100 villages in center of Vientiane capital city by using survey methods. A hedonic price analysis was conducted to determine the marginal return to different land characteristics using an econometric model corrected for correlation. Parcel characteristics such as distance to public park, village income, distance of population, number of the school within 500 meters buffer, distance to the temple, distance to the major market and distance to the business center （CBD）. Arc GIS 9.2 was applied to calculate the distance of the factors, after that SPSS 15.0 was used to calculate the land price characteristic based on hedonic price model. The results showed that the distance to the center of population was the main factor influencing to the land price, and followed by school and village income. Map of the land price before and after hedonic price analysis were produced. The land price valuation approaches based on hedonic price model for Vientiane capital city were developed and land price map were predicted. Hedonic price model and GIS were very useful for this research, and finally the policy of the land valuation based on GIS was developed.

Study on Soil Nutrient Fertility of Cultivated Land in Laos

[Objectives] This study was conducted to explore the differences in soil nutrient contents of cultivated land in different regions of Laos,and to provide a basis for soil nutrient management and scientific fertilization in Laos. [Methods] By collecting 166 samples of the 0-20 cm cultivated soil layer from farmland in the farming areas of Luang Namtha Province in the northern part of Laos and Vientiane Province in the middle of the country,the contents of soil organic matter,total nitrogen,available phosphorus,available potassium,available calcium and available magnesium were analyzed,so as to evaluate the current status of soil nutrient fertility and explore the differences in soil nutrient contents of regional cultivated land. [Results] The soil organic matter was relatively abundant,the total nitrogen and available potassium contents were at the lower-middle level,and the available phosphorus,available calcium and available magnesium were insufficient or extremely insufficient. The soil nutrient contents of cultivated land were different in different regions. [Conclusions] It is suggested that lime or other alkaline fertilizers should be applied on the farmland with acid soil,and nitrogen,phosphorus,and potassium fertilizers should be added at the same time to improve soil nutrient fertility.

Several boundary identification methods of gravity data and application in Vientiane of Laos area

The authors studied the potential field boundary identification of the new technology in order to find out the possible fractures or contact zones using the following methods such as tilt derivative,horizontal derivative of tilt derivative,normalized standard deviation and normalized differential method. Combined with Euler deconvolution and small subdomain filtering,the actual data processing results show that these methods are all able to identify wider range extending fractures and obtain abundant geological information. The horizontal derivative of tilt derivative and normalized differential method have a better resolution for the small cutting fractures and lacunae in the studied area. They provide a reliable basis for study of the cutting relationship between fractures.

Field Observations of the Vulnerable Impressed Tortoise, Manouria impressa, from Southern Laos and Notes on Local Chelonian Trade

Observations of wild chelonians in Indochina are uncommon with most records and specimens coming from the commercial wildlife trade. During the surveys of the Xe Sap National Protected Area in southern Laos between February and May 2012, four impressed tortoises, Manouria impressa （IUCN Red List： Vulnerable） were found in three separate field locations. There are few published observations of this species in the wild. We also present data on threats and local value of chelonians in the wildlife trade.

Key Determinants of Optimal Breastfeeding Practices in Laos

This paper provides information on optimal breastfeeding practices in the People’s Democratic Republic of Lao from data collected in the2011 Lao Social Indicator Survey. Results: Early initiation of breastfeeding within the first hour of life occurred among 39.6% of Laotian infants. After controlling for the effects of wealth, early initiation of breastfeeding was found to be most prevalent among mothers with higher education, those who received antenatal services, and those who delivered in a health facility. Avoidance of prelacteal feeds within the first three days of life occurred among 65% of Laotian infants, and was highest among ethnic Hmong and Khmer infants, and among those born in public versus private health facilities. Avoidance of prelacteal feeds was lowest after deliveries in which a traditional birth attendant was present. Exclusive breastfeeding through the first 5 months of age was reported among 40.8% of infants nationally. Ethnicity again played a role with the highest levels of exclusive breastfeeding found to occur among ethnic Khmer infants (69.4%, OR 2.8, CI: 1.5 - 5.1). Discussion: These results highlight the role that health care workers can have on early breastfeeding practices at the point of both antenatal counseling and in the delivery setting. Strengthening the quality of counseling on infant feeding can have a significant impact on early initiation of breastfeeding. Ethnic difference significantly impact both early and exclusive breastfeeding practices. Conclusion: A complexity of factors at different levels of care impact breastfeeding practices. A synergy of strategic approaches are needed to target antenatal counseling as well as post-delivery practices, all which account for the unique social and cultural attitudes towards infant feeding. Stronger community-based interventions that account for cultural attitudes and practices are most likely to be successful in promoting exclusive and continued breastfeeding practices.

Palynological Assemblage Age and Palaeoenvironment of the Cretaceous Salt-bearing Strata in Laos and Yunnan,China

The study of Cretaceous-Palaeogene salt-bearing strata of the Khorat Basin Laos and the Lanping-Simao Basin in Yunnan,China has an great significance not only in explaining the basin evolution and the genesis of potash

Geological Features,Mineralization Types and Metallogenic Setting of the Phlaythong Large Iron Deposit,Southern Laos

The Phlaythong large iron deposit in Shampasak of southern Laos,is located in the Kon Tum microblock （Fig.1A）,central-southern part of the Indo-China block,and the geographic coordinate of the central mining area is 14°43′04″ N and 106°07′02″ E.

Effects of puddling on percolation and rice yields in rainfed lowland paddy cultivation: Case study in Khammouane province, central Laos

We investigated the effects of puddling on percolation and rice yields in rainfed lowland paddy cultivation. We selected a study village in Khammouane province, central Laos, and set up non-puddling and puddling plots from high to low positions. Even when puddling was conducted carefully, the ponding water in the plots disappeared in the case of little rainfall. Further, percolatifons during the later periods of rice growth increased drastically. Therefore, it is difficult to overcome drought stresses only by conducting puddling. We also compared the water conditions in the non-puddling and puddling plots. In the puddling plots at high position and low position along a stream, the number of days without ponding water in the puddling plots was less than that in the non-puddling field in July, suggesting the possibility of a different transplanting date. We tried to estimate the effects of transplanting date on the rice yields and found that transplanting 15 days earlier leads to an increase of 0.5 t/ha in the rice yields. Moreover, the profits from the increased yields exceed the puddling costs considerably, leading to a definite increase in income. Because the transplanting date has no effects in the fields with high ground water, puddling is effective in paddy fields where ponding does not occur to a significant degree.

Laos:"Happy Chinese New Year Temple Fair" Held in Vientiane

Laos:''Happy Chinese New Year Temple Fair" Held in Vientiane Year, the two-day "Happy Chinese New Year Temple Fair" was held at Laos National Cultural Hall from January 26 to 27. Hebei Acrobatics Troupe presented excellent performances to local people.

Analysis of the Relationship Between GDP and FDI on the Economic Growth of Laos

In the current globalization stream,the foreign investment is an important role not only for developed country but at all especially the least developing country as Laos.This study aims to examine the relationship between the gross domestic product(GDP)and foreign direct investment(FDI)on economic growth of Laos by using data from 1985 to 2014.The long run relationship was analyzed by Johansen co-integration test and estimated the speed of adjustment by Vector Error Correction approach.Estimated results indicated that there was long run relationship running from FDI to GDP and the relation would return to the equilibrium in about 19 when it occurred.This study suggests that policy maker should improve the other factor for motivated FDI and accelerate Lao economy.