Red River Water Research Articles

Quantitation of glyphosate, glufosinate, and AMPA in drinking water and surface waters using direct injection and charged-surface ultra-high performance liquid chromatography-tandem mass spectrometry

Herbicides glyphosate (N-(phosphonomethyl)glycine) and glufosinate (2-amino-4-(hydroxymethylphosphinyl)butanoic acid) and the main transformation product of glyphosate, aminomethanephosphonic acid (AMPA), are challenging to analyze for in environmental samples. The quantitative method developed by this study adapts previously standardized dechlorination procedures coupled to a novel charged surface C18 column, ultra-high performance liquid chromatography-tandem mass spectrometry, polarity switching, and direct injection. The method was applied to chlorinated tap water, as well as river samples, collected in the City of Winnipeg and rural Manitoba, Canada. Using only syringe filtration without derivatization, the validated method resulted in good accuracies in both tap and surface water, at both 2 and 20 μg L−1. Method limits of detection (MLD) and quantification (MLQ) ranged from 0.022/0.074 to 0.11/0.36 μg L−1, with precisions of 0.46–2.2% (intraday) and 1.3–7.3% (interday). The mean (SEM) of the pesticides in μg L−1 for tap water were 0.11 (0.007) (AMPA), glufosinate and glyphosate < MLDs; and for Red River water were 0.56 (0.045) (AMPA), glufosinate < MLQ, and glyphosate 0.40 (0.072). For the smaller tributaries, glufosinate was >MLD but < MLQ once and that was for Shannon Creek at 0.2 μg L−1. For the remaining rivers, the mean concentrations ranged from 0.31 to 3.1 μg L−1 for AMPA, and 0.087–0.53 μg L−1 for glyphosate. The method will be ideal for supporting monitoring and risk assessment programs that require high throughput sampling and quantitative methods capable of producing robust results that leverages chromatographic and mass spectrometric paradigms instead of being extraction technology focused.

First hydrological study on the seasonal occurrence of glyphosate, glufosinate, and their metabolites in the Red River system, North Vietnam

We report the spatial and seasonal distribution of organophosphorus herbicides, namely glyphosate (GLYP), glufosinate (GLUF), and their respective metabolites aminomethyl phosphonic acid (AMPA) and 3-(methylphosphinico)-propionic acid (MPPA), in the Red River system (North Vietnam), a major water body in Southeast Asia. The four compounds were measured at 34 sampling stations located from upstream to the estuary during the dry (March) and wet (July) seasons in 2019. Large seasonal variations in herbicide concentrations were measured for the four analytes from upstream to the estuary, with the highest range of variations observed during the wet season. In the surface waters of the Red River, the maximum concentrations of GLUF (234 ng L–1), GLYP (565 ng L–1) and its metabolite AMPA (1329 ng L–1), occurred in the wet season. These values however, are lower than reported in other rivers worldwide. In contrast, the estimated fluxes of these compounds in the Red River water basin were very high during the wet season, i.e., up to 121, 50.2, 284, and 186 kg d–1 for GLYP, GLUF, AMPA, and MPPA, respectively. During both seasons, we observed correlations between the four compounds and ammonium (NH4+), suggesting that both nitrogen containing fertilizers and herbicides were applied in areas close to the river shore. The concentrations and fluxes of the herbicides GLYP, GLUF, and their metabolites determined in the Red River were compared to those recorded in other world river systems, such as the Garonne River (France), thus highlighting the importance of monitoring these compounds in surface waters.

Evaluation of Interaction between Surface Water and Groundwater in the South of Hanoi City by Stable Isotope Technique

The δ18O and δ2H stable isotope techniques for studying properties of groundwater and surface help us to understand more clearly about the distribution and movement of groundwater in the South of Hanoi area. There were 68 water samples from the studying area and analyzed by a Liquid Water Isotope Analyzer (LWIA-24D). The stable isotope values of the groundwater from Pleistocene aquifers were range from -3.21‰ to -9.55‰ δ18O and -35.32‰ to -67.44‰ δ2H; rainwater from -8.18‰ to -4.13‰ δ18O and -61.19‰ to -17.93‰ δ2H; Red river water from -7.51‰ to -5.29‰ δ18O and -51.60‰ to -38.99‰ δ2H. Based on stable isotope characteristics, the results show that there was a relationship between surface water and groundwater in the South of Hanoi city. It is that groundwater recharges for river water in the dry season with 74%, and in the rainfall season groundwater is recharged from river with 87%.

Classification of hydrogeological structure along the Red River in the Hanoi area

Hanoi city has abundant groundwater, supplemented by the surface water (mainly Red River) all year round, and the extensive shallow aquifers, which are easily exploited by large-diameter wells. There always exists some open hydrogeological windows in the Red River area with an open structure; therefore, the groundwater has a strained hydraulic relationship with the Red River water system Along the Red River from Ba Vi to the end of Phu Xuyen district, there are nine regions with three types and four sub-types of different hydrogeological structures. In particular, the sub-type I-A of the groundwater has a tight hydraulic correlation with the Red River since the hydrogeological structure of the Red River bottom includes three aquifers: Holocene (qh), upper Pleistocene (qp2), and lower Pleistocene (qp1) that constructs a hydraulic system. The sub-type I-B is characterized by the hydrogeological structure at the Red River bottom, including the aquitard in Vinh Phuc and two aquifers qp2 and qp1, which form a hydraulic system. The sub-type II-A is distinguished by the fact that the Red River crosses the aquifer qh; there are no aquitards between the aquifer qh and qp2 to form a hydraulic system; the aquitard separates the aquifer qp1. The sub-type II-B is identified by the fact that the Red River crossing the aquifer qh; there is an aquitard between the aquifer qh and qp2; there are no aquitards between the aquifer qp2 and qp1 so that can create a hydraulic system. Type III has a solid existence of both aquifers and aquitards; thus, the hydraulic relationship between the Red River and the aquifers qp2 versus qp1 is inferior.

Establishing an empirical equation for the relationship between total suspended solids and total phosphorus concentrations in the downstream Red river water

Recently, the Asian rivers have faced the strong reduction of riverine total suspended solids (TSS) flux due to numerous dam/reservoir impoundment. The Red river system is a typical example of the Southeast Asian rivers that has been strongly impacted by reservoir impoundment in both China and Vietnam, especially in the recent period. It is known that the reduction in total suspended solids may lead to the decrease of some associated elements, including nutrients (N, P, Si) which may affect coastal ecosystems. In this paper, we establish the empirical relationship between total suspended solids and total phosphorus concentrations in water environment of the Red river in its downstream section from Hanoi city to the Ba Lat estuary based on the sampling campaigns conducted in the dry and wet seasons in 2017, 2018 and 2019. The results show a clear relationship with significant coefficient between total suspended solids and total phosphorus in the downstream Red river. It is expressed by a simple equation y = 0.0226x0.3867 where x and y stand for total suspended solids and total phosphorus concentrations (mg/l) respectively with the r2 value of 0.757. This equation enables a reasonable prediction of total phosphorus concentrations of the downstream Red river when the observed data of total suspended solids concentrations are available. Thus, this work opens up the way for further studies on the calculation of the total phosphorus over longer timescales using daily available total suspended solids values.

DNA BARCODING APPLICATION OF MITOCHONDRIAL COI GENE TO IDENTIFY SOME FISH SPECIES OF FAMILY GOBIIDAE IN VIETNAM

The Red river system is a typical example of Southeast Asian rivers that is strongly impacted by human and climatic conditions, especially in the recent period. In this paper, we aim to investigate the longitudinal variation of the water quality of the Red river, in the section from Hanoi city to the Ba Lat estuary. The sampling campaigns were conducted in the dry seasons in 2017 and 2018. The monitoring results showed that the average concentrations of nutrients (NO2-, NO3-, NH4+, PO43-) were still lower than the allowed values of the Vietnamese standard limits for surface water quality (QCVN 08:2015/BTNMT, column A1) whereas the average concentrations of Cl- and TSS exceeded the allowed values of the QCVN 08:2015/BTNMT, column A1 4.6 and 2.3 times, respectively. NO3- and dissolved silica (DSi) concentrations showed a significant variation from the Hanoi site to the Ba Lat site (6.62 mg/l to 1.19 mg/l for NO3- and 5.21 mg/l to 2.14 mg/l for DSi) whereas SO42-, NO2- and Cl- increased markedly in this longitudinal section, especially from the point SH6 where the salinity started to increase. Based on the three different methods for classification of trophic levels and on the different variables observed during the dry seasons in 2017–2018, the nutrient concentrations of the Red river water tended to slightly increase from the site Hanoi (SH1) to the site SH5 at Nam Dinh, indicating the increase of nutrient external input along the river whereas it tended to decrease from the site SH6 (at mesotrophic/eutrophic level) to the last observed site SH9 (at oligotrophic/mesotrophic level) at the sea due to the dilution of seawater. Seawater in dry season could affect directly the river downstream about 35 km far from the sea. The results may be a guide for planning of water use including agricultural irrigation in the Red river estuary.

Origin of the Redwater River Drainage Basin Determined by Topographic Map Interpretation: Eastern Montana, USA

Topographic and geologic map interpretation strongly suggests the eastern Montana Redwater River valley eroded headward across large southeast-oriented ice-marginal melt water floods. The north-oriented Redwater River heads in an area to the south of recognized continental glaciation and flows into the recognized glaciated region before joining the east-oriented Missouri River. Detailed topographic maps show the eastern drainage divide is asymmetric with steeper slopes on the Redwater River side and is crossed by shallow dry valleys linking northwest-oriented Redwater River tributaries with southeast-oriented streams that flow as barbed tributaries to the northeast-oriented Yellowstone River. The western drainage divide is also crossed by shallow dry valleys linking northwest-oriented drainage routes to north-oriented Missouri River tributaries with southeast-oriented and barbed tributaries to the northeast- and north-oriented Redwater River. Alluvium from upstream Yellowstone River source areas found within the Redwater River drainage basin suggests the Redwater River and much longer Yellowstone River valleys eroded headward from a continental ice sheet margin as headward erosion of the larger Yellowstone River valley across the southeast-oriented flood flow was supplemented by northeast- and north-oriented flow moving at the present day Redwater-Yellowstone River drainage divide elevation.

Change in carbon flux (1960–2015) of the Red River (Vietnam)

Global riverine carbon concentrations and fluxes have been impacted by climate and human-induced changes for many decades. This paper aims to reconstruct the longterm carbon concentrations and carbon fluxes of the Red River, a system under the coupled pressures of environmental change and human activity. Based on (1) the relationships between particulate and dissolved organic carbon (POC, DOC) or dissolved inorganic carbon (DIC), and suspended sediments (TSS) or river water discharge and on (2) the available detailed historical records of river discharge and TSS concentration, the variations of the Red River carbon concentration and flux were estimated for the period 1960–2015. The results show that total carbon flux of the Red River averaged 2555 ± 639 kton C year−1. DIC fluxes dominated total carbon fluxes, representing 64% of total, reflecting a strong weathering process from carbonate rocks in the upstream basin. Total carbon fluxes significantly decreased from 2816 kton C year−1 during the 1960s to 1372 kton C year−1 during the 2010s and showed clear seasonal and spatial variations. Organic carbon flux decreased in both quantity and proportion of the total carbon flux from 40.9% in 1960s to 14.9% in 2010s, reflecting the important impact of dam impoundment. DIC flux was also reduced over this period potentially as a consequence of carbonate precipitation in the irrigated, agricultural land and the reduction of the Red River water discharge toward the sea. These decreases in TSS and carbon fluxes are probably partially responsible for different negatives impacts observed in the coastal zone.

Fate of Arsenic during Red River Water Infiltration into Aquifers beneath Hanoi, Vietnam.

Recharge of Red River water into arsenic-contaminated aquifers below Hanoi was investigated. The groundwater age at 40 m depth in the aquifer underlying the river was 1.3 ± 0.8 years, determined by tritium–helium dating. This corresponds to a vertical flow rate into the aquifer of 19 m/year. Electrical conductivity and partial pressure of CO2 (PCO2) indicate that water recharged from the river is present in both the sandy Holocene and gravelly Pleistocene aquifers and is also abstracted by the pumping station. Infiltrating river water becomes anoxic in the uppermost aquifer due to the oxidation of dissolved organic carbon. Further downward, sedimentary carbon oxidation causes the reduction of As-containing Fe-oxides. Because the release of arsenic by reduction of Fe-oxides is controlled by the reaction rate, arsenic entering the solution becomes highly diluted in the high water flux and contributes little to the groundwater arsenic concentration. Instead, the As concentration in the groundwater of up to 1 μM is due to equilibrium-controlled desorption of arsenic, adsorbed to the sediment before river water started to infiltrate due to municipal pumping. Calculations indicate that it will take several decades of river water infiltration to leach arsenic from the Holocene aquifer to below the World Health Organization limit of 10 μg/L.

Disease burden due to gastrointestinal infections among people living along the major wastewater system in Hanoi, Vietnam

BackgroundDespite recent improvements of wastewater treatment capacities in urban areas of Hanoi, Vietnam, microbial pollution is still considerable. There is a paucity of burden estimates due to gastrointestinal infection in people living along the wastewater system, and among people who are in direct contact with the wastewater, such as farmers using wastewater in agriculture and aquaculture. MethodsA quantitative microbial risk assessment (QMRA) was pursued focussing on four population groups characterised by different levels of exposure to wastewater: (i) workers maintaining the wastewater conveyance and treatment systems; (ii) urban farmers using wastewater from To Lich River; (iii) community members in urban areas exposed to flooding events in the districts of Hoang Mai and Thanh Tri; and (iv) peri-urban farmers in Thanh Tri district, where Red River water is used for agriculture and aquaculture. The QMRA was developed on the basis of measured concentration of Escherichia coli and Salmonella spp. and Ascaris spp. eggs in water samples. Published ratios between measured organisms and pathogenic strains of norovirus, rotavirus, Campylobacter spp., pathogenic E.coli, pathogenic Salmonella spp., Cryptosporidium spp. and Ascaris lumbricoides were employed to estimate annual risk of gastrointestinal infection and disease burden. ResultsThe QMRA estimated a disease burden of 0.011 disability-adjusted life years (DALYs) per person per year in urban farmers, 0.006 DALYs for sanitation workers, 0.0005 DALYs for urban communities at risk of flooding events and 0.0004 DALYs for peri-urban farmers. Urban farmers had considerably higher incidence estimates for gastrointestinal disease episodes per year (2.0) compared to the other exposure groups (≤ 1.0). ConclusionsUrban farmers using wastewater from To Lich River have a high gastrointestinal disease burden, which is about 100 times larger than the health-based targets for wastewater use set by the World Health Organization. These findings are of direct public health relevance and call for upgrading Hanoi's wastewater system to reduce microbial contamination. Finally, this study presents a first example on how to link QMRA to a sanitation safety planning (SSP) approach in an Asian context and its findings are interesting in the frame of Sustainable Development Goal (SDGs) #6.

Relationship of dissolved inorganic carbon (DIC) concentrations with some environmental variables in the Red River water in the period 2008 - 2015

Dissolved Inorganic Carbon (DIC) is one of the main chemical components in water and very sensitive with environmental changes. DIC content in river water closely relates with natural weathering process and human activities in the whole basin. Therefore, DIC concentration reflects the impact of natural conditions and human activities in the basin to river water quality. This paper presents the survey results of the DIC concentrations at 4 sites in the Red River system during the period from January 2008 to December 2015 and simultaneously considers the relationship between some environmental variables and the DIC concentrations in the river water. The survey results showed that the DIC concentrations in the Red River water varied from 9.1 to 29.9 mgC.L-1, averaging 19.6 mgC.L-1 during the study period. The DIC concentrations are positively correlated with pH values and some major ions concentrations in river water, such as K+, Na+, Ca2+, SO42- but negatively correlated with water temperature. These relationships also indicate that the DIC concentrations in the Red River water are influenced by natural conditions, rather than by human activities in the river basin.&#x0D; Cacbon vô cơ hòa tan (DIC) là thành phần hóa học cơ bản trong nước và rất nhạy cảm với những thay đổi của các yếu tố môi trường. DIC có mối liên hệ chặt chẽ với sự phong hóa tự nhiên và các hoạt động của con người trên quy mô toàn lưu vực. Do đó, DIC phản ánh mức độ tác động của các điều kiện tự nhiên và con người trong lưu vực tới chất lượng nước sông. Bài báo trình bày kết quả quan trắc hàm lượng DIC trong nước sông Hồng, đồng thời xem xét mối quan hệ giữa một số yếu tố môi trường với hàm lượng DIC trong nước sông trong giai đoạn 1/2008 – 4/2015. Kết quả cho thấy hàm lượng DIC trong nước sông Hồng dao động trong khoảng 9,1 to 29,9 mgC.L-1, trung bình đạt 19,6 mgC.L-1 trong giai đoạn tháng 1 năm 2008 – tháng 12 năm 2015. Hàm lượng DIC có mối tương quan theo tỷ lệ nghịch với nhiệt độ nước sông; đồng thời có mối tương quan tỷ lệ thuận với giá trị pH và hàm lượng một số ion như K+, Na+, Ca2+, SO42-... tại 4 vị trí quan trắc trên sông Hồng. Các mối quan hệ này thể hiện rằng hàm lượng DIC trong nước sông Hồng chịu ảnh hưởng chính của các đặc điểm tự nhiên hơn là các tác động của con người trong lưu vực.

Potential effects of climate change on streamflow for seven watersheds in eastern and central Montana

Abstract Study region Eastern and central Montana. Study focus Fish in Northern Great Plains streams tolerate extreme conditions including heat, cold, floods, and drought; however changes in streamflow associated with long-term climate change may render some prairie streams uninhabitable for current fish species. To better understand future hydrology of these prairie streams, the Precipitation-Runoff Modeling System model and output from the RegCM3 Regional Climate model were used to simulate streamflow for seven watersheds in eastern and central Montana, for a baseline period (water years 1982–1999) and three future periods: water years 2021–2038 (2030 period), 2046–2063 (2055 period), and 2071–2088 (2080 period). New hydrological insights for the region Projected changes in mean annual and mean monthly streamflow vary by the RegCM3 model selected, by watershed, and by future period. Mean annual streamflows for all future periods are projected to increase (11–21%) for two of the four central Montana watersheds: Middle Musselshell River and Cottonwood Creek. Mean annual streamflows for all future periods are projected to decrease (changes of −24 to −75%) for Redwater River watershed in eastern Montana. Mean annual streamflows are projected to increase slightly (2–15%) for the 2030 period and decrease (changes of −16 to −44%) for the 2080 period for the four remaining watersheds.

HYDROGEOPHYSICS TECHNIQUES TO AQUIFER LOCATING AND MONITORING FOR INDUSTRIAL ZONE NORTH THANGLONG AND QUANGMINH, HANOI

HYDROGEOPHYSICS TECHNIQUES TO AQUIFER LOCATING AND MONITORING FOR INDUSTRIAL ZONE NORTH THANGLONG AND QUANGMINH, HANOI

Occurrence of perfluoroalkyl acids in environmental waters in Vietnam

This is the first nationwide study of perfluoroalkyl acids (PFAAs) in environmental waters in Vietnam. Twenty-eight river water and 22 groundwater samples collected in four major cities and 14 river water samples from the Red River were screened to investigate the occurrence and sources of 16 PFAAs. Perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were the most prevalent of 11 detected PFAAs with maximum concentrations in urban river water of 5.3, 18 and 0.93ngL−1, respectively, and in groundwater of 8.2, 4.5 and 0.45ngL−1, respectively. PFAAs in the Red River water were detected at low levels. PFAA concentrations in river water were higher in the rainy season than in the dry season, possibly due to storm water runoff, a common phenomenon in Southeast Asian countries. The highest concentrations of PFAAs in river water were observed in samples from highly populated and industrialized areas, perhaps sourced from sewage. The PFAA concentrations observed were similar to those in other Southeast Asian countries, but lower than in developed nations. From the composition profiles of PFAAs, industrial products containing PFAAs imported from China and Japan might be one of the major sources of PFAAs in the Vietnamese aquatic environment. According to the health-based values and advisory issued by the United States Environmental Protection Agency (USEPA), the concentrations of detected PFAAs in this study do not pose an immediate health risk to humans and aquatic organisms.

Water quality of the Red River system in the period 2012 - 2013

Few data are available on the quality of Red river water that is used for multi-purposes, including for domestic water demand in some rural areas. This paper presents the observation results of the Red River water quality in two years 2012 and 2013. The monitoring results showed that the average concentrations of nutrients (N, P) were still far lower than the allowed value of the Vietnamese standard limits for surface water quality (QCVN 08:2008/BTNMT, column A2). Due to the impoundment of two big dams in the Da tributary, the suspended solids contents in river water decreased remarkably. The dissolved heavy metal (DHM) concentrations varied in a high range: Cu: 10 – 80 mg.l-1; Zn: 2 – 88 mg.l-1; Cr: 0.2 – 5.1 mg.l-1; Pb: 2 - 107 mg.l-1; Cd: 2 – 12 mg.l-1; Mn: 2 - 35 mg.l-1; and Fe: 160 – 2370 mg.l-1. Most of the mean values of DHM were lower than the allowed values of the QCVN 08:2008/BTNMT, but at several points of time, several DHM (e.g. Fe, Cd, Pb) contents exceeded the allowed values. The Total Coliform (TC) and Fecal Coliform (FC) densities varied in a high range: TC: 23 to 13,000MPN.100ml-1 and FC: 0 to 1,600MPN.100ml-1 and they exceeded the allowed values QCVN 08:2008/BTNMT at several points observed. The dissolved organic carbon (DOC) contents were in low level and the particulate organic carbon (POC) content mainly derived from soil organic leaching and erosion in the basin. The results underlined the need for regularly monitoring the river water quality, and there should be some effective solutions to manage and treat the waste sources in order to provide safe water for different actual purposes use in the Red River basin.&#x0D; Rất ít số liệu sẵn có về chất lượng nước sông Hồng, dòng sông được sử dụng cho nhiều mục đích, bao gồm cả cung cấp nước sinh hoạt ở một số vùng nông thôn. Bài báo trình bày các kết quả quan trắc chất lượng nước sông Hồng trong hai năm 2012 và 2013. Kết quả quan trắc cho thấy chất dinh dưỡng (N, P) thấp xa so với giới hạn cho phép của tiêu chuẩn Việt Nam về chất lượng nước mặt (QCVN 08: 2008/BTNMT cột A2). Do có hai hồ chứa trên sông Đà, hàm lượng chất rắn lơ lửng trong nước sông giảm đáng kể. Các kim loại nặng hòa tan (DHM) có hàm lượng dao động trong khoảng rộng: Cu: 10-80 g.l-1; Zn: 2-88 g.l-1; Cr: 0,2-5,1 g.l-1; Pb: 2-107 g.l-1; Cd: 2-12 g.l-1; Mn: 2-35 g.l-1; và Fe: 160 - 2370 g.l-1. Hầu hết các giá trị trung bình của DHM thấp hơn giá trị cho phép của quy chuẩn QCVN 08: 2008/BTNMT, tuy nhiên, tại một số thời điểm, một số DHM (ví dụ Fe, Cd, Pb) có hàm lượng vượt quá giới hạn cho phép. Mật độ tổng coliform (TC) và coliform phân (FC) dao động trong khoảng rộng: TC: 23 đến 13,000MPN.100ml-1 và FC: 0 đến 1,600MPN.100ml-1 và tại một số thời điểm mật độ TC và FC vượt giá trị cho phép của Quy chuẩn QCVN 08:2008/BTNMT. Hàm lượng cabon hữu cơ hòa tan (DOC) ở mức thấp, và hàm lượng cacbon hữu cơ dạng không tan (POC) chủ yếu có nguồn gốc từ đất rửa trôi và xói mòn trong lưu vực. Kết quả quan trắc nhấn mạnh nhu cầu giám sát thường xuyên chất lượng nước sông, và nên có các giải pháp hiệu quả để quản lý và xử lý các nguồn gây ô nhiễm trong lưu vực nhằm cung cấp nước sạch cho các mục đích sử dụng nước sông Hồng như hiện nay.

Hydrological and hydrogeological characterization of groundwater and river water in the North Hanoi industrial area, Vietnam

Degradation of groundwater quality by human activities is a widespread environmental problem in Vietnam. Groundwater there is a major source of water for domestic and industrial purposes. This paper reviews, compiles, and comprehensively analyzes spatiotemporal variations of hydrological and hydrogeological characteristics of shallow and deep groundwater aquifers in northern Hanoi industrial zones and in nearby Red River water. Groundwater level, electrical conductivity, and water temperature were measured in six monitoring wells, complemented by anion, cation, and stable isotope analyses of ground and surface water. The results show that the groundwater in both shallow and deep aquifers was fresh, but mainly calcium-bicarbonate type contaminants and human activities affect groundwater and surface water composition. With the goal of devising sustainable water use regulations, more research must be directed toward long-term monitoring of groundwater and surface water quality, as well as toward detailed investigation of the hydraulic characteristics of local aquifers in the study area.

Potential Environment and Public Health Risk Due to Contamination of Heavy Metals from Industrial Waste Water in Lam Thao, Phu Tho, Vietnam

Problem statement: In Vietnam, rice cultivation plays an important ro le in national economic development and food security. However, rice production is facing many problems associated with rapid industrialization and urbaniz ation in the country. Resultant emissions of solid and liquid wastes are often untreated and discharge d directly to agricultural land. These practices ha ve potential impacts on the environment and human health. Approach: The research was carried out within the frame of the collaborative research proj ect Towards the mitigation of environment and public health risks due to heavy metal contaminatio n in irrigated rice-based systems of Vietnam in 2006-2010. The study was implemented in the Lam Thao district, Phu Tho province with the aim to assess the effects of wastewater and other contamin ation sources on the environment and public health. Results: Surface water and soil in the field showed signs o f significant contamination by wastewater from the industrial zones. Bio-indicators (DO, COD, BOD5) in the surface water were also strongly affected by waste. Paddy fields around the industri al zones had an elevated risk of heavy metal contamination (Cu, Zn, As, Cd and Pb), with concent rations exceeding Vietnamese Maximum Acceptable Concentrations (MACs) for Cu, Zn, Cd and Pb. Soil contamination with heavy metals was resulting in elevated concentrations in rice grain. Where consumption of locally-produced food was high, exposure of individuals to heavy metals could present a public health risk. The partial Hazard Quotient (HQ; a ratio derived from comparing estima ted exposure to heavy metals, i.e., Cd, (with safe' daily doses) for ric e and vegetables (water spinach) and the integrated Hazard Quotient of rice and vegetables (HQi) was co nsistently greater in areas with soil contamination than in the reference area using Red River water fo r irrigation. The HQi for Cd was particularly high for children below the age of 13 and it was slightl y higher for females than for males. While toxicologically-derived 'safe' daily doses are very conservative to account for inherent uncertain ty in their derivation, this issue should be raised with famers and policy makers. Conclusion/Recommendations: Due to unrestricted discharge of industrial waste, the soil and water environment has been contaminated, which is demonstrated by accumulation of heavy metals in surface soils. This may in some circumstances pose a risk t o public health. Policies should be developed that enable authorities to mitigate negative environment al impacts of industry and empowers communities to nurture a safer environment whilst maintaining the economic benefits of development.

Acoustic analysis of Zhuang long and short vowels

The contrast of long and short vowels and the acoustic features and physiological rules of long vowels in Hongshuihe (lit. Red Water River) dialect of Zhuang are investigated in this paper. The results show that in isolated words read at normal speed, there are evident differences in the durations of long and short vowels. But different vowels behave differently. Due to phonetic physiology, when long vowels are pronounced, the tongue is higher for high vowels, lower for low vowels, more front for front vowels and more back for back vowels. The pitch and power of short vowels are higher than for corresponding long vowels. Finally, physiological explanations for the above phenomena are given.

Acoustic analysis of Zhuang long and short vowels

The contrast of long and short vowels and the acoustic features and physiological rules of long vowels in Hongshuihe (lit. Red Water River) dialect of Zhuang are investigated in this paper. The results show that in isolated words read at normal speed, there are evident differences in the durations of long and short vowels. But different vowels behave differently. Due to phonetic physiology, when long vowels are pronounced, the tongue is higher for high vowels, lower for low vowels, more front for front vowels and more back for back vowels. The pitch and power of short vowels are higher than for corresponding long vowels. Finally, physiological explanations for the above phenomena are given.

Controlling geological and hydrogeological processes in an arsenic contaminated aquifer on the Red River flood plain, Vietnam

Geological and hydrogeological processes controlling recharge and the mobilization of As were investigated in a shallow Holocene aquifer on the Red River flood plain near Hanoi, Vietnam. The geology was investigated using surface resistivity methods, geophysical borehole logging, drilling of boreholes and installation of more than 200 piezometers. Recharge processes and surface–groundwater interaction were studied using (i) time-series of hydraulic head distribution in surface water and aquifers, (ii) the stable isotope composition of waters and (iii) numerical groundwater modeling. The Red River and two of its distributaries run through the field site and control the groundwater flow pattern. For most of the year, there is a regional groundwater flow towards the Red River. During the monsoon the Red River water stage rises up to 6 m and stalls the regional groundwater flow. The two distributaries recharge the aquifer from perched water tables in the dry season, whilst in the flooding period surface water enters the aquifer through highly permeable bank sediments. The result is a dynamic groundwater flow pattern with rapid fluctuations in the groundwater table. A transient numerical model of the groundwater flow yields an average recharge rate of 60–100 mm/a through the confining clay, and a total recharge of approximately 200 mm/a was estimated from 3H/3He dating of the shallow groundwater. Thus in the model area, recharge of surface water from the river distributaries and recharge through a confining clay is of the same magnitude, being on average around 100 mm/a. The thickness of the confining clay varies between 2 and 10 m, and affects the recharge rate and the transport of electron acceptors (O2, NO3- and SO42-) into the aquifer. Where the clay layer is thin, an up to 2 m thick oxic zone develops in the shallow aquifer. In the oxic zone the As concentration is less than 1 μg/L but increases in the reduced zone below to 550 μg/L. In the Holocene aquifer, As is mobilized at a rate of around 14 μg/L/a. An As mass balance for the field site shows that around 1100 kg of As is annually leached from the Holocene sand and discharged into the Red River, corresponding to 0.01% of the total pool of As now present in the Holocene sand.