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This paper provides an update checklist of species-level identified myxosporean species from marine and freshwater fishes in Vietnam. The list includes 51 nominal myxosporean species (38 marine and 13 freshwater) belonging to 9 genera: Myxobolus (26 species); Kudoa (6 species); Henneguya (6 species); Thelohanellus (5 species); Unicapsula (2 species); Ceratomyxa (2 species), Zschokkella (2 species); Auerbachia (1 species), and Meglitschia (1 species). For each parasite species, information on morphological characteristics of myxospore, fish hosts, infection sites, and collection locality in Vietnam along with GenBank accession number of nucleotide sequence data and the line drawings were provided. In addition, taxonomic status of several species was discussed and Myxobolus eszterbaueri nom. nov. is proposed as a junior homonym for Myxobolus hakyi Baska, Voronin, Eszterbauer, Müller, Marton & Molnár 2009.

People who drink groundwater in rural areas of Southeast Asia are exposed to pathogens and arsenic (As)-related health problems. A water treatment system consisting of electrocoagulation reactors, using iron (Fe) electrodes and a filtration tank, was designed to treat complex contaminated groundwater for drinking. Its applicability was demonstrated near the Red River in Vietnam. The water treatment system reduced 10.3 CFU/mL of total coliform and 376 μg/L of As(III) in the groundwater to 0 CFU/mL and 6.68 μg/L, respectively. Total coliforms were attenuated by Fe(II) infiltration or enmeshed during Fe precipitate formation. Of the total As, 43% formed As(III) complexation with the Fe precipitates and the other 57% was oxidized to As(V) then adsorbed to Fe precipitates. The Fe precipitates, containing total coliforms and As, were separated from the discharge water in the filtration tank. The system required 49 W of power to operate, which equates to 423 kWh/year, to continuously purify 0.5 t water/day. This requirement was powered by a 380–750 W solar panel, without external energy supply, making the water treatment system an appropriate option for addressing drinking water problems in rural areas.

Water pollution with arsenic (As) and heavy metals has been a major considering issue because of their negative impact on ecosystems and human health. This study was conducted to evaluate the adsorption behavior of As and heavy metals by iron ore sludge modified by the addition of 10% sodium silicate solution and heating at 400°C (SBC2-400-10S) in both batches and fixed–bed column experiments. The kinetics showed that the removal of As and heavy metals by the adsorbent is a pseudo-second-order reaction. The adsorption data fitted well with Langmuir isotherm and provided Langmuir monolayer capacity (mg/g) of As and heavy metals in the following order: Pb (2.379) > Cd (2.008) > Zn (1.915) > Mn (1.692) > As (0.452). The column adsorption data were fairly well described by Thomas model, with the order of Thomas adsorption capacity following a similar trend as in the batch study. The results of this study indicated that SBC2-400-10S was a potential adsorbent for removal of As and heavy metals from solutions.

Equisetum diffusum D. Don was transplanted into solutions added with different concentrations of Mn, Zn, Cd, Pb, and As for 30 days in the laboratory experiment to assess the removal of these metals and their accumulation in the plant. The highest removal efficiency of Mn, Zn, Cd, Pb, and As from solutions by E. diffusum was 99.6, 97.9, 77.5, 85.3, and 61.9%, respectively. The highest daily removal efficiencies of heavy metals were obtained after 1 day of new solution addition. The highest concentrations of Mn, Zn, Cd, Pb, and As in the plant roots were 7230, 1490, 174, 1170, and 274 mg/kg-DW, respectively; those in the shoots were 1960, 566, 33.9, 308, and 108 mg/kg-DW. The bioconcentration factor (BCF) values for Mn, Zn, Cd, Pb, and As were 496, 406, 702, 463, and 191, respectively. The results of this study indicate that E. diffusum has the ability to remove simultaneously these metals from water, making it a potential species for phytoremediation of water contaminated with multiple heavy metals.

The present research was conducted to propose the index for assessing the effectiveness of science and technology projects in Vietnam. The effectiveness of projects was measured through 20 variables of 03 indicators: (1) The effectiveness of science and technology values including 12 variables; 2) The effectiveness of human resources including 04 variables; 3) and the effectiveness of education and training including 04 variables. These variables were evaluated by the 0-1 scale, with the zero-value indicated ineffectiveness of projects and vice versa. These variables were measured by the number of results, products from selected projects, and compared with the actual value in the project contract. Total 8 projects (including natural sciences, social sciences and technology projects) from National Science and Technology Program for Sustainable Development of North West Vietnam (NSTP-SDNW) were selected from 58 projects of NSTP-SDNW for testing the present index. Research results showed that the number of results and products of all projects have been met or exceeded requirements in project contracts. The assessment value of social projects (code 06X, 07X, 17X) ranged from 0.55 to 0.75, whereas the assessment value of natural sciences and technology projects ranged from 0.55 to 0.72. Research results showed that all selected projects are measured as high effective level, with the highest effectiveness was observed in No. 06X and No. 02C projects.

This research aims to assess different filter materials in horizontal subsurface flow constructed wetland (CW) planted with combined Phragmites australis Cav. and Cyperus alternifolius L. for treatment of real swine wastewater at a large pig farm in Vietnam. Four CW models including CW1 (gravel), CW2 (gravel, limestone), CW3 (gravel, limestone, and sand), and CW4 (gravel, limestone, and rice husk) were designed and conducted during 90 days of the experiments. The results showed that the removal efficiencies of chemical oxygen demand (COD), total suspended solids (TSS), nitrogen, and phosphorus from swine waster by the CW3 and CW4 models were higher than those by CW1 and CW2. The highest removal efficiency of COD, NH4+-N, TN, and TP by CW3 was 82 ± 2%, 82 ± 4%, 77 ± 1%, and 82 ± 3%, respectively. The result of this study indicates the capacity of combined gravel, limestone, and sand as suitable substrate filter for swine wastewater treatment.

Acidic failure is relatively common in anaerobic digesters that receive readily biodegradable food wastes at high loading. Under low pH conditions, the activity of methanogenic biomass decreases resulting in complete failure of the digestion process. In this experimental study, we demonstrated that one of the causes for the digester failure under low pH conditions is due to accelerated decay of methanogenic biomass. When enriched acetate degrading methanogens were exposed to a low pH environment (pH = 5.1 with phosphoric acid) in a batch experiment without external substrate, the specific decay rate was observed to increase as much as 10 times of that at pH 7.0. The specific decay rate for formate degrader was also found to increase under low pH conditions whilst the fermentative microorganisms in the cultures appeared to be tolerant to low pH conditions. A Propidium Mono-Azide-quantitative Polymerase Chain Reaction (PMA-qPCR) analysis revealed that the archaeal biomass dominated by methanogens dropped by 71–79% from the initial concentration after 6 days of the acidic batch experiment whilst the bacterial biomass dominating acidogens decreased by only 25%. The decrease in the number of living cells in the batch experiments at different pH was monitored with time to determine a correlation between decay rate and incubation pH.

Land use change has been assessed widely using Remote Sensing (RS) and Geographic Information System (GIS) techniques. The analysis of land use change was done by detecting land cover change. A study about land cover change, along with the self-employed workers’ perception towards changes between 2007 and 2017 were carried out in Nam Tu Liem District, Hanoi, Vietnam. The result of the study shows that the built-up lands have increased and remained to be the dominant land cover types in 2017. The agriculture has been declining mainly due to conversion into built-up land. Other land type including water, bare land, and vegetation have shown slight changes throughout the years. Overall changes from 2007 to 2017 shown that built-up land gained the most and agriculture land lost the most. On the other hand, the perception study’s major findings indicate that about two-thirds (69%) of respondents are aware of changes. However, almost one-third (31%) are unaware of the said topic. There are several factors that may affect the awareness of self-employed workers which will be cursory discussed in the study. This study in Nam Tu Liem District is a first step to determine and understand the major driving factors and their impacts on the land use changes in the area. A detailed land use/cover change study and a larger population size for perception studies are recommended in order for the government to formulate policies to achieve sustainable development.

In this study, we developed an innovative spherical biochar with high porosity and excellent paracetamol (PRC) adsorption capacity. The optimal pyrolysis temperatures for the preparation of spherical biochar (derived from pure glucose) and non-spherical biochar (from pomelo peel wastes) were obtained at 900 °C and 700 °C, respectively. Various advanced techniques were applied to characterize the prepared biochars. Spherical and non-spherical biochars exhibited large specific surface area (1292 and 1033 m2/g) and high total pore volume (0.704 and 1.074 cm3/g), respectively. The adsorption behavior of PRC onto two biochars was conducted utilizing batch experiments. Results demonstrated that the adsorption process was slightly affected by the change of solution pH (2-11) and addition of NaCl (0.05-1.0 M) and was able to achieve fast equilibrium (∼120 min). The maximum adsorption capacity of spherical biochar (286 mg/g) for PRC was approximately double that of non-spherical biochar (147 mg/g). The signal of thermodynamic parameters was negative ΔG° and ΔH° values, but positive ΔS° value. The adsorption mechanism consisted of pore-filling, hydrogen bonding formations, n-π and π-π interactions, and van der Waals force. The adsorption capacities of two biochars were insignificantly dependent on different real water samples containing PRC. Consequently, the biochars can serve as a green and promising material for efficiently removing PRC from water.

Water pollution by heavy metals has currently been an increasing worldwide concern. This study was conducted to assess the removal efficiency of a treatment system using sorbent and common reed (Phragmites australis). Approximately 1400 g of sorbent that was modified from Ban Cuon iron mine drainage sludge by adding 10% sodium silicate solution and heating at 400 °C was put in a column of 1.8l. The initial concentrations of As and Cd in inflow water were 1.0 mg/l, those of Pb, Mn, and Zn were 6.0 mg/l. During 30 days of the laboratory experiment, aqueous solution of constant flow rate (50 l/day) was pumped through the sorbent column before flowing into surface and horizontal subsurface constructed wetlands using P. australis. The results showed that the removal efficiency of As, Cd, Mn, Pb and Zn by sorbent – surface constructed wetland were 83.0 – 89.5, 89.3 – 93.3, 69.7 – 98.0, 94.8 – 95.4, and 69.2 – 92.3%, respectively; those by sorbent – subsurface constructed wetland were 85.3 – 89.1, 98.5 – 98.7, 92.8 – 98.7, 95.5 – 96.0, and 93.1 – 96.2%. The concentrations of heavy metals in the outlet water met the National Technical Regulation on Industrial Wastewater of Vietnam (QCVN 40:2011–BTNMT) with the exception of As, which indicates the effectiveness of combined sorbent and P. australis for simultaneous removal of these metals from contaminated water.

Mangrove forests are important in providing habitats for complex communities of terrestrial and marine fauna. Moreover, they are recognized as highly productive ecosystems in providing nutrients to mangrove food webs or exporting them to nearby coastal waters. In the present study, stable isotopes of carbon and nitrogen were applied to examine the changes in the diets of benthic invertebrate communities following mangrove restoration. The isotope signature of invertebrate tissues varied among the forest ages and locations and ranged from 3.7 &plusmn, 1.0 to 13.9 &plusmn, 1.1&permil, and &minus, 26.6 &plusmn, 0.5 to &minus, 15.0 &plusmn, 0.4&permil, for &delta, 15N and &delta, 13C, respectively. The results showed that the food source assimilation of macro-invertebrates is slightly altered from a mixture of benthic microalgae and marine phytoplankton in the mudflat to a combination of benthic microalgae and sediment organic matter in the Sonneratia caseolaris and the Kandelia obovata forests. Therefore, the diets of macro-invertebrates varied following forest ages and the position of the forest in the intertidal zone. These insights from the present study are useful for the effective conservation and restoration of mangrove forests in Vietnam and worldwide.

Arsenic (As) contaminated groundwater has been a major concern due to the negative impacts to exposed people. This research was conducted to assess and compare the removal efficiency of As from groundwater by laterite, sand, and ash. The experiment was carried out in 14 days in a household scale in Son Dong commune, Hoai Duc district, Ha Noi. Groundwater was pumped directly from a well and flowed through 20 cm (diameter) x 80 cm (length) columns. The initial As concentration in groundwater was 526 µg/L decreasing to an average of 189, 192 and 154 µg/L after being filtrated using sand, ash, and laterite, respectively. Average removal efficiency of sand, ash and laterite during the experiment was 63.3, 63.9, and 70.5%, respectively. Laterite had higher As removal efficiency may be due to higher content of goethite and kaolinite in this sorbent which resulted in better adsorption of As. The concentrations of As in the outflow water were higher than the allowable limit set by the national technical regulation on drinking water quality (QCVN 01:2009/BYT). Therefore, it requires higher volume of sorbents or additional treatment technologies for removal of As from groundwater. Ô nhiễm asen (As) trong nước ngầm hiện nay là một vấn đề cấp bách đối với xã hội bởi những rủi ro tiềm ẩn với sức khoẻ con người. Nghiên cứu được thực hiện nhằm đánh giá và so sánh khả năng hấp phụ As trong nước ngầm của đá ong, cát và tro. Thí nghiệm được tiến hành trong vòng 14 ngày đặt tại một hộ gia đình có nguồn nước ngầm bị ô nhiễm As thuộc xã Sơn Đồng, huyện Hoài Đức, Hà Nội. Nước ngầm được bơm từ giếng và chảy qua các cột đựng vật liệu có đường kính và chiều dài lần lượt là 20 cm và 80 cm. Nồng độ As ban đầu là 526 µg/L đã giảm xuống còn 189, 192 và 154 µg/L sau khi lọc bằng cát, tro và đá ong. Hiệu suất xử lý As trung bình của cát, tro và đá ong lần lượt là 63,3, 63,9 và 70,5 µg/L. Đá ong xử lý As tốt hơn có thể do hàm lượng goethit và kaolinit cao hơn trong vật liệu hấp phụ này dẫn đến khả năng hấp phụ As tốt hơn. Tuy nhiên hàm lượng As trong nước đầu ra vẫn chưa đạt quy chuẩn cho nước uống (QCVN 01:2009/BYT). Do đó, cần tăng thêm lượng vật liệu hoặc kết hợp với các phương pháp khác để xử lý As hiệu quả hơn., Journal of Vietnamese Environment, Vol 9 No 4 (2018)

Allylthiourea is a known specific inhibitor for ammonium oxidiser to suppress its oxygen uptake, and is commonly used for various kinds of batch respirometric tests to detect heterotrophic respiration in activated sludge. However, when high heterotrophs were present in the sample, it appeared the inhibitor was noticeably degraded and reached below the inhibition threshold after a couple of days, which resulted in overestimation of the heterotrophic respiration. The biological decomposition of the inhibitor was expressed with a Monod-type rate expression having a half-saturation coefficient of 980 mg-COD/L and maximum specific growth rate of 1.0 d−1. The developed kinetic model, including the growth and decay of the heterotrophs and nitrifiers, indicated that the ATU with about 90 mg-ATU/L which was initially dosed to the system would reach below the inhibition threshold of 1.0 mg-ATU/L after 10 days when 750 mg-COD/L of heterotrophs were present. From the kinetic model, an empirical formula to calculate a safe minimum ATU dose for the batch respirometric test was elaborated. The model also provided a modified experimental procedure to accurately estimate the initial heterotrophic biomass concentration in the sample and its specific decay rate based on IWA Activated Sludge Models.

In field survey, Pteris vittata and Pityrogramma calomelanos were only found in arsenic (As) contaminated areas with soil pH 7.2–8.8 and 2.3–4.2, respectively. In the first pot experiment, two fern species were grown on the soil amended with 300 mg kg−1 As at soil pH of 5.1, 7.2 and 9. P. calomelanos survived all pH treatments, and had the highest frond As concentration and soil As removal efficiency at soil pH 5.1. All P. vittata plants were dead at soil pH 5.1. P. vittata had higher frond As concentration, biomass and the amount of As removed from the soil than those of P. calomelanos at soil pH of 7.2 and 9. In the second pot experiment, P. vittata was demonstrated to have greater life time, biomass, As tolerance and accumulation than those of P. calomelanos as planted on alkaline soil (pH 7.8) spiked with various concentrations of As.

This study was carried out to evaluate the sorption capacity of Pb, As, Cd, Zn, and Mn by laterite from Tam Duong District (Vinh Phuc Province) and Thach That District (Hanoi City). Laterite sam- ples were exposed to different initial concentrations of heavy metals in solutions (2.5, 5.0, 10, 20, and 50 mg/l) at pH = 5.5 during 24 hours. The results demonstrated that sorption capacity of heavy metals was in the following order: Pb> As> Cd> Zn>Mn. The highest sorption capacity of Pb, As, Cd, Zn, and Mn of laterite from Tam Duong was 1553, 756, 397, 281, and 143 mg/kg, respectively and the highest removal efficiency was 94, 76, 70, 56 and 37%. The results indicated that laterite from Tam Duong District showed lower sorption capacity than that from Thach That District. The disparity sorption capacity of Pb, As, Cd, Zn, Mn between laterite from Thach That and Tam Duong was 10.3–11.6, 11.9–17.9, 11.5–13.7, 9.5–17.6, and 11.1–14.3%, respectively. Laterites from Tam Duong and Thach That are a promising environmental material which can be used in the removal of heavy metals from wastewater. Nghiên cứu này được thực hiện nhằm đánh giá khả năng hấp phụ Pb, As, Cd, Zn, và Mn bởi laterit đá ong khu vực huyện Tam Dương (Vĩnh Phúc) và huyện Thạch Thất (Hà Nội). Mẫu đá ong được tiến hành thí nghiệm trong các dung dịch có hàm lượng kim loại nặng ban đầu khác nhau (2,5; 5,0; 10; 20 và 50 mg/l) tại pH=5,5 trong 24 giờ. Kết quả nghiên cứu cho thấy mức độ hấp phụ kim loại nặng bởi laterit đá ong lần lượt là Pb> As> Cd> Zn>Mn. Dung lượng hấp phụ Pb, As, Cd, Zn và Mn cao nhất của laterit Tam Dương lần lượt là 1553, 756, 397, 281 và 143 mg/kg và hiệu suất hấp phụ cao nhất lần lượt là 94, 76, 70, 56 và 37%. Dung lượng hấp phụ kim loại nặng của laterit huyện Tam Dương thấp hơn khu vực huyện Thạch Thất. Sự chênh lệch về dung lượng hấp phụ Pb, As, Cd, Zn và Mn giữa laterit Thạch Thất và laterit Tam Dương lần lượt là 10,3–11,6; 11,9–17,9; 11,5– 13,7; 9,5–17,6 và 11,1–14,3%. Kết quả nghiên cứu bước đầu cho thấy đá ong khu vực huyện Tam Dương và Thạch Thất là vật liệu hấp phụ tiềm năng phục vụ ứng dụng trong xử lý nước thải bị nhiễm kim loại nặng., Journal of Vietnamese Environment, Vol 8 No 4 (2016)

Phytoremediation is a plant-based, environment-friendly, and cost-effective technology that can be potentially used to remediate contaminated media. This study was conducted to evaluate the phytoextraction and phytostabilization potential, two common techniques of phytoremediation, of 21 plant species growing naturally at the largest tungsten (W) mine in Vietnam—the second largest production of W in the world. The average concentrations in different soil fractions were in the following order: residue > organically complexed, Fe- and Mn oxide-bound > carbonate bound > exchangeable. The total concentrations of arsenic (As), cadmium (Cd), copper (Cu), and zinc (Zn) in the soil varied by 34–3390, 4.87–81.6, 14.3–2080, and 21.9–370 mg/kg, respectively. The concentrations of As, Cd, Cu, and Zn in the shoots ranged 0.71–2400, 0.05–5.55, 4.81–249, and 13.3–380 mg/kg-DW, respectively. The concentrations of As and Cd in all soil samples and Cu in 70% of soil samples collected around the mine fluctuated within 2–227, 3–54, and up to 21-folds higher than the maximum allowable limit for agricultural soils in Vietnam (QCVN 03-MT:2015/BTNMT). The results indicated that hyperaccumulation levels (mg/kg-DW) were obtained for only As in Pityrogramma calomelanos (2400) and Pteris vittata L. (1860). Based on the recorded hyperaccumulation levels, translocation and accumulation factors, biomass, and fast growth of these plants, P. calomelanos and P. vittata were considered to be promising native plants for the phytoextraction of As contaminated soils. Bidens pilosa L. also has great potential for phytostabilization of mining soils contaminated with As and heavy metals.

A natural factors-based approach was developed to examine proactive responses to hazards and improving sustainability on the Chan May-Lang Co Gulf area, Central Vietnam. The approach was based on a weight-of-evidence method within an integrated and quantitative vulnerability assessment in which the spatial relationship between a set of evidential factors (lithology, distance to the coastline, altitude, slope, aspect, drainage, wind speed during storms, and land use and cover) and a set of hazard locations was combined with the prior probability (total vulnerability) to obtain the posterior probability of hazard occurrence. The result showed that 44.3 % of the study area had high to very high total vulnerability, due to the high density of vulnerable objects and frequency of severe damage from typhoons, floods, landslides, and erosion. The result also demonstrated that the contribution of natural factors was directly proportional to total vulnerability in approximately 75 % of the study area, indicating a high dependence of vulnerability on natural factors. In the remaining areas, low contributions were found in the high and very high vulnerability areas dominated by high anthropogenic activities. In contrast, natural factors were important contributors to total vulnerability in areas characterized by dense vegetation, consolidated rocks, and altitude greater than 300 m, reflecting high natural resilience. The present study demonstrated that a proactive approach may provide appropriate measures to mitigate hazards and to increase the sustainability of the study area.

This study was carried out to evaluate the sorption capacity of Pb, As, Cd, Zn, and Mn by laterite from Tam Duong District (Vinh Phuc Province) and Thach That District (Hanoi City). Laterite samples were exposed to different initial concentrations of heavy metals in solutions (2.5, 5.0, 10, 20, and 50 mg/l) at pH = 5.5 during 24 hours. The results demonstrated that sorption capacity of heavy metals was in the following order: Pb> As> Cd> Zn>Mn. The highest sorption capacity of Pb, As, Cd, Zn, and Mn of laterite from Tam Duong was 1553, 756, 397, 281, and 143 mg/kg, respectively and the highest removal efficiency was 94, 76, 70, 56 and 37%. The results indicated that laterite from Tam Duong District showed lower sorption capacity than that from Thach That District. The disparity sorption capacity of Pb, As, Cd, Zn, Mn between laterite from Thach That and Tam Duong was 10.3–11.6, 11.9–17.9, 11.5–13.7, 9.5–17.6, and 11.1–14.3%, respectively. Laterites from Tam Duong and Thach That are a promising environmental material which can be used in the removal of heavy metals from wastewater. Nghiên cứu này được thực hiện nhằm đánh giá khả năng hấp phụ Pb, As, Cd, Zn, và Mn bởi laterit đá ong khu vực huyện Tam Dương (Vĩnh Phúc) và huyện Thạch Thất (Hà Nội). Mẫu đá ong được tiến hành thí nghiệm trong các dung dịch có hàm lượng kim loại nặng ban đầu khác nhau (2,5; 5,0; 10; 20 và 50 mg/l) tại pH=5,5 trong 24 giờ. Kết quả nghiên cứu cho thấy mức độ hấp phụ kim loại nặng bởi laterit đá ong lần lượt là Pb> As> Cd> Zn>Mn. Dung lượng hấp phụ Pb, As, Cd, Zn và Mn cao nhất của laterit Tam Dương lần lượt là 1553, 756, 397, 281 và 143 mg/kg và hiệu suất hấp phụ cao nhất lần lượt là 94, 76, 70, 56 và 37%. Dung lượng hấp phụ kim loại nặng của laterit huyện Tam Dương thấp hơn khu vực huyện Thạch Thất. Sự chênh lệch về dung lượng hấp phụ Pb, As, Cd, Zn và Mn giữa laterit Thạch Thất và laterit Tam Dương lần lượt là 10,3–11,6; 11,9–17,9; 11,5– 13,7; 9,5–17,6 và 11,1–14,3%. Kết quả nghiên cứu bước đầu cho thấy đá ong khu vực huyện Tam Dương và Thạch Thất là vật liệu hấp phụ tiềm năng phục vụ ứng dụng trong xử lý nước thải bị nhiễm kim loại nặng.

Phytoremediation is an environmental remediation technique that takes advantage of plant physiology and metabolism. The unique property of heavy metal hyperaccumulation by the macrophyte Eleocharis acicularis is of great significance in the phytoremediation of water and sediments contaminated by heavy metals at mine sites. In this study, a field cultivation experiment was performed to examine the applicability of E. acicularis to the remediation of water contaminated by heavy metals. The highest concentrations of heavy metals in the shoots of E. acicularis were 20 200 mg Cu/kg, 14 200 mg Zn/kg, 1740 mg As/kg, 894 mg Pb/kg, and 239 mg Cd/kg. The concentrations of Cu, Zn, As, Cd, and Pb in the shoots correlate with their concentrations in the soil in a log-linear fashion. The bioconcentration factor for these elements decreases log-linearly with increasing concentration in the soil. The results indicate the ability of E. acicularis to hyperaccumulate Cu, Zn, As, and Cd under natural conditions, making it a good candidate species for the phytoremediation of water contaminated by heavy metals.

Eleocharis acicularis was exposed to different concentrations of In, Ag, Pb, Cu, Cd, and Zn in the laboratory to assess its capability in accumulating these metals. After 15 days, 477 mg/kg dry wt. of In was accumulated by the roots; concentrations of Ag, Pb, Cu, Cd, and Zn in the shoots were 326, 1120, 575, 195, and 213 mg/kg dry wt., respectively. The results indicate that E. acicularis has the ability to accumulate these metals from water, making it a good candidate species for phytoremediation and phytomining.

Sb, As, Cu, and Zn toxicity and contamination have become a growing concern in recent years. Phytoremediation, a plant based and cost effective technology, may be an effective approach in the cleanup of water contaminated by these metals. In this study, the aquatic macrophyte Eleocharis acicularis was used in laboratory and field experiments to assess its capability to accumulate Sb, As, Cu, and Zn, and thereby investigate its potential application in phytoremediation. The results showed that E. acicularis adapted well to water contaminated by these metals. The removal rates of Sb, As, Cu, and Zn in the laboratory experiment were 3.04, 2.75, 0.417, and 1.49 μg/L/ day, respectively. The highest concentrations of these metals accumulated in E. acicularis after 10 days of the laboratory experiment were 6.29, 6.44, 20.5, and 73.5 mg/kg dry weight, respectively. Only 8% of As, 12% of Sb, 87% of Cu and 93% of Zn removed from the water were used by E. acicularis. The highest concentrations of Sb, As, Cu, and Zn accumulated in E. acicularis after 10 wk of the field experiment were 76.0, 22.4, 33.9, and 266 mg/kg dry weight, respectively. The results indicate that E. acicularis has the ability to accumulate Sb, As, Cu, and Zn from contaminated water.

Phytoremediation, a plant-based and cost-effective technology for the cleanup of contaminated soil and water, is receiving increasing attention. In this study, the aquatic macrophyte Eleocharis acicularis was examined for its ability to take up multiple heavy metals and its potential application for phytoremediation at an abandoned mining area in Hokkaido, Japan. Elemental concentrations were measured in samples of E. acicularis, water, and soil collected from areas of mine tailing and drainage. The results reveal that Pb, Fe, Cr, Cu, Ni, and Mn accumulation in the plants increased over the course of the experiment, exceeding their initial concentrations by factors of 930, 430, 60, 25, 10, and 6, respectively. The highest concentrations of Fe, Pb, Zn, Mn, Cr, Cu, and Ni within the plants were 59500, 1120, 964, 388, 265, 235, and 47.4 mg/kg dry wt., respectively, for plants growing in mine drainage after 11 months of the experiment. These results indicate that E. acicularis is a hyperaccumulator of Pb. We also found high Si concentrations in E. acicularis (2.08%). It is likely that heavy metals exist in opal-A within cells of the plant. The bioconcentration factors (BCF: ratio of metal concentration in the plant shoots to that in the soil) obtained for Cr, Cu, Zn, Ni, Mn, and Pb were 3.27, 1.65, 1.29, 1.26, 1.11, and 0.82, respectively. The existence of heavy metals as sulphides is thought to have restricted the metal-uptake efficiency of E. acicularis at the mine site. The results of this study indicate that E. acicularis shows great potential in the phytoremediation of mine tailing and drainage rich in heavy metals.

To study the geological control on groundwater As concentrations in Red River delta, depth-specific groundwater sampling and geophysical logging in 11 monitoring wells was conducted along a 45 km transect across the southern and central part of the delta, and the literature on the Red River delta's Quaternary geological development was reviewed. The water samples (n=30) were analyzed for As, major ions, Fe 2+ , H 2 S, NH 4 , CH 4 , δ 18 Ο and 8D, and the geophysical log suite included natural gamma-ray, formation and fluid electrical conductivity. The SW part of the transect intersects deposits of grey estuarine clays and deltaic sands in a 15-20 km wide and 50-60m deep Holocene incised valley. The NE part of the transect consists of 60-120 m of Pleistocene yellowish alluvial deposits underneath 10-30m of estuarine clay overlain by a 10-20m veneer of Holocene sediments. The distribution of δ 18 O-values (range -12.2‰ to -6.3%o) and hydraulic head in the sample wells indicate that the estuarine clay units divide the flow system into an upper Holocene aquifer and a lower Pleistocene aquifer. The groundwater samples were all anoxic, and contained Fe 2+ (0.03-2.0mM), Mn (0.7-320μM), SO 4 (

Joint Research on Environmental Science and Technology for the Earth

Geoenvironmental and geoecological integrated technology (GGIT) is a cost-effective and environment-friendly technology that encompasses the applications of earth science principles and functions of geological environment and ecosystems to assimilate and minimize the spread of pollutants, to enhance the sorption capacity and environmental remediation. On the basis of the integrated approaches such as system, anthropogenic activities – ecosystem – environment interaction, effectiveness and feasibility, GGIT has provided significant applications in Vietnam such as waste containment and remediation and environmental protection. The results of a pilot scale using iron mine drainage sludge and common reed (Phragmites australis) for wastewater treatment in a Pb-Zn mine in northern Vietnam indicated the effective and potential application of GGIT. However, GGIT has many challenges in limited funding conditions, constraints in the initial development of GGIT, incomplete transfer to users, and quantitative assessment of pollutant cleanup by natural environments and ecosystems. Environmental pollution quote, impacts to exposed organisms, increasing demands for application of low-cost technologies, the availability of potential sorbents, indigenous plants, and ecosystems for environmental remediation, and collaboration will promote development, contribution, and implementation of GGIT applications in Vietnam.

Arsenic contamination of shallow groundwater is among the biggest health threats in the developing world. Targeting uncontaminated deep aquifers is a popular mitigation option although its long-term impact remains unknown. Here we present the alarming results of a large-scale groundwater survey covering the entire Red River Delta and a unique probability model based on three-dimensional Quaternary geology. Our unprecedented dataset reveals that ∼7 million delta inhabitants use groundwater contaminated with toxic elements, including manganese, selenium, and barium. Depth-resolved probabilities and arsenic concentrations indicate drawdown of arsenic-enriched waters from Holocene aquifers to naturally uncontaminated Pleistocene aquifers as a result of > 100 years of groundwater abstraction. Vertical arsenic migration induced by large-scale pumping from deep aquifers has been discussed to occur elsewhere, but has never been shown to occur at the scale seen here. The present situation in the Red River Delta is a warning for other As-affected regions where groundwater is extensively pumped from uncontaminated aquifers underlying high arsenic aquifers or zones.