Arsenic contamination in groundwater and its possible sources in Hanam, Vietnam

This study investigated the arsenic (As) level in groundwater, and the characteristics of aquifer sediment as related to the occurrence of As in groundwater in Hanam, Vietnam. The deposition and transport of As-containing substances through rivers were also examined. Arsenic concentrations in 88% of the groundwater samples exceeded the As limit for drinking water based on the WHO standards. The dominating form of arsenic was As(III). The maximum total As content in bore core sediment was found in a peat horizon of the profiles and generally, elevated levels of As were also found in other organic matter-rich horizons. Total As contents of the bore core sediments were significantly correlated with crystalline iron oxide, silt and clay contents, suggesting that As in aquifer sediment was mainly associated with iron (hydr)oxides and clay mineral. In the groundwater, As concentration showed significant correlations with the total concentrations of Fe and HCO (3)(-). Significant correlations between HCl-extractable As and non-crystalline Fe oxide, total C, N, and S were also observed in the profiles. The results support the hypothesis that under favorable reductive conditions established by the degradation of organic matter, the dissolution of iron (hydr)oxides releases adsorbed As into the groundwater. The deposition of As in the sediments from the Red River were significantly higher than that in the Chau Giang River, suggesting that the Red River is the main source of As-containing substances deposited in the study area.     

Oxidation of organophosphorus pesticides with chloroperoxidase enzyme in the presence of an ionic liquid as co-solvent

Effects of selected ionic liquids on the efficiency of CPO oxidation of methyl-parathion were studied. In general, the activity of CPO decreases with the increased concentration of ionic liquid. For ionic liquids with the same cation, those with PF₆ ^? exhibit strongest inhibition toward CPO, while those with either BF₄ ^? or metSO₄ ^? show relatively lesser inhibition. It was further demonstrated that even for buffer solutions containing up to 30% concentration of ionic liquids such as EAN, BMIMmetSO₄, and EtPyTFA, CPO still can retain high activity (70–100% compared to that in citrate buffer) for oxidation of methyl-parathion. Photothermal enhancement factors of 3.5 times and corresponding improvements of sensitivity in the determination of organophosphates by the FIA-TLS method are predicted in 30% ionic liquids.     

Optimization of esterification of fatty acid rubber seed oil for methyl ester synthesis in a plug flow reactor

To date, non-food vegetable oil has been considered as the primary source for biodiesel production. Rubber seed oil has high acid value (34 mgKOH/g) and can be used for biodiesel synthesis. The purpose of this study was to investigate esterification of fatty acid, which derived from rubber seed oil, in a plug flow reactor system at high temperature and low methanol consumption. Response surface methodology was applied for design experiment and optimization of esterification reaction. Temperature, methanol consumption, and sulfuric acid were chosen as variables to examine their influence in a conversion to methyl ester. At 140°C, at 5:1 methanol to fatty acid ratio (by mole), H₂SO₄ 1.5 (%v/w), and space time 20 min, the conversion to methyl ester attained 98.2%. Fourier transform infrared spectroscopy (FTIR) and gas chromatography-Mass spectrometry (GC-MS) were used for analysis and to confirm the formation of methyl ester. Methyl ester was characterized for biodiesel fuel properties in accordance to ASTM standard.     

Unusual arsenic speciation in sea anemones

Nine species of sea anemones (Anthopleura asiatica, Actinia equina, Actinodendron arboreum, Phymanthus loligo, Entacmaea actinostoloides, Stichodactyla gigantea, S. haddoni, S. mertensii and Metridium senile) contained arsenic in the range of 1.6-7.0microg As g(-1) (wet mass basis). Irrespective of the species, water-soluble arsenic compounds accounted for more than 80% of the total arsenic. Analysis of water-soluble arsenic compounds by LC/ESI-MS revealed that four arsenicals, arsenobetaine (AB), trimethylarsoniopropionate, arsenocholine (AC) and tetramethylarsonium ion (TEMA), are contained in most species but arsenate, methylarsonic acid, dimethylarsinic acid and trimethylarsine oxide are absent in all species. Interestingly, compositional patterns of the four arsenicals greatly differed from species to species. Only three species (S. gigantea, S. haddoni and M. senile) contained AB at the highest proportions, similar to the majority of marine animals. However, the remaining six species showed unusual compositional patterns of arsenic compounds; AC was most predominant in A. arboreum and P. loligo and TEMA in A. asiatica, A. equina, E. actinostoloides and S. mertensii. On the whole, high proportions (24.6-87.1% of the water-soluble arsenic) of TEMA appear to be a peculiar characteristic of many species of sea anemones. Thus, sea anemones are an important animal group in the arsenic cycling, especially in that they may be donors of TEMA to predators.     

Measuring the association of environmental,corporate, financial,and social CSR: evidence from fuzzy TOPSIS nexus in emerging economies

Environmental Science and Pollution Research - The purpose of this research is to measure the combing impact of corporate social responsibility on company performance and to conduct a comparative...     

Using individual-based movement information to identify spatial conservation priorities for mobile species

The optimal design of reserve networks and fisheries closures depends on species occurrence information and knowledge of how anthropogenic impacts interact with the species concerned. However, challenges in surveying mobile and cryptic species over adequate spatial and temporal scales can mask the importance of particular habitats, leading to uncertainty about which areas to protect to optimize conservation efforts. We investigated how telemetry-derived locations can help guide the scale and timing of fisheries closures with the aim of reducing threatened species bycatch. Forty juvenile speartooth sharks (Glyphis glyphis) were monitored over 22 months with implanted acoustic transmitters and an array of hydrophone receivers. Using the decision-support tool Marxan, we formulated a permanent fisheries closure that prioritized areas used more frequently by tagged sharks and considered areas perceived as having high value to fisheries. To explore how the size of the permanent closure compared with an alternative set of time-area closures (i.e., where different areas were closed to fishing at different times of year), we used a cluster analysis to group months that had similar arrangements of selected planning units (informed by shark movements during that month) into 2 time-area closures. Sharks were consistent in their timing and direction of migratory movements, but the number of tagged sharks made a big difference in the placement of the permanent closure; 30 individuals were needed to capture behavioral heterogeneity. The dry-season (May–January) and wet-season (February–April) time-area closures opened 20% and 25% more planning units to fishing, respectively, compared with the permanent closure with boundaries fixed in space and time. Our results show that telemetry has the potential to inform and improve spatial management of mobile species and that the temporal component of tracking data can be incorporated into prioritizations to reduce possible impacts of spatial closures on established fisheries.     

Sensitivity Analysis of Aggregated Indices for Integrated Assessment with a Case Study of the Mid-Atlantic Region

Environmental indicators are often aggregated into a single index for various purposes in environmental studies. Aggregated indices derived from the same data set can differ, usually because the aggregated indices' sensitivities are not thoroughly analyzed. Furthermore, if a sensitivity analysis is carried out, it is not presented in a transparent fashion to policy decision-makers. This paper presents a method of generating various aggregated environmental indices and analyzing their sensitivities via the use of the fuzzy set concept. Results show that several insights into the environmental conditions of the study area (e.g., the distribution of good or bad values of indicators at a watershed and or across the region) can be revealed in the sensitivity analysis of aggregated indices.