The fate of arsenic in groundwater discharged to the Meghna River, Bangladesh

2018 ◽  
Vol 15 (2) ◽  
pp. 29 ◽  
Author(s):  
Michelle Berube ◽  
Katrina Jewell ◽  
Kimberly D. Myers ◽  
Peter S. K. Knappett ◽  
Pin Shuai ◽  
...  
Keyword(s):  
River Water ◽  
Solid Phase ◽  
Sediment Cores ◽  
Hydrologic Processes ◽  
Reactive Barrier ◽  
Arsenic In Groundwater ◽  
Phosphate Leaching ◽  
Induced Changes ◽  
The Ganges ◽  
The Impact

Environmental contextArsenic contamination of groundwater is a major environmental problem in many areas of the world. In south-east Asia, iron-rich reducing groundwater mixes with oxidising river water in hyporheic zones, precipitating iron oxides. These oxides can act as a natural reactive barrier capable of accumulating elevated solid-phase concentrations of arsenic. AbstractShallow, anoxic aquifers within the Ganges–Brahmaputra–Meghna Delta (GBMD) commonly contain elevated concentrations of arsenic (As), iron (Fe) and manganese (Mn). Highly enriched solid-phase concentrations of these elements have been observed within sediments lining the banks of the Meghna River. This zone has been described as a Natural Reactive Barrier (NRB). The impact of hydrological processes on NRB formation, such as transient river levels, which drive mixing between rivers and aquifers, is poorly understood. We evaluated the impact of groundwater flow dynamics on hydrobiogeochemical processes that led to the formation of an Fe- and Mn-rich NRB containing enriched As, within a riverbank aquifer along the Meghna River. The NRB dimensions were mapped using four complementary elemental analysis methods on sediment cores: X-ray fluorescence (XRF), aqua regia bulk extraction, and HCl and sodium phosphate leaching. It extended from 1.2 to 2.4 m in depth up to 15 m from the river’s edge. The accumulated As was advected to the NRB from offsite and released locally in response to mixing with aged river water. Nearly all of the As was subsequently deposited within the NRB before discharging to the Meghna. Significant FeII release to the aqueous phase was observed within the NRB. This indicates the NRB is a dynamic zone defined by the interplay between oxidative and reductive processes, causing the NRB to grow and recede in response to rapid and seasonal hydrologic processes. This implies that natural and artificially induced changes in river stages and groundwater-tables will impact where As accumulates and is released to aquifers.

scholarly journals Geochemical characteristics of arsenic in groundwater during riverbank filtration: a case study of Liao River, Northeast China

2020 ◽  
Vol 20 (8) ◽  
pp. 3288-3300
Author(s):  
Shuai Lu ◽  
Xiaoyu Feng ◽  
Xiaosi Su
Keyword(s):  
Water Level ◽  
River Water ◽  
Manganese Oxides ◽  
Solid Phase ◽  
Water Infiltration ◽  
Riverbank Filtration ◽  
Arsenic Content ◽  
Groundwater Exploitation ◽  
Groundwater Environment ◽  
Arsenic In Groundwater

Abstract Affected by groundwater exploitation in the riverside, the infiltration of river water to recharge groundwater will cause changes in the groundwater environment, which has an important impact on the geochemical behavior of arsenic in groundwater. In this study, the groundwater environment zones in the process of river water infiltration were divided, and the arsenic content in groundwater in the study area had a good correlation with the environment zones. In the weak oxidation environment zone and the weak reductive environment zone, as the distance from the riverbank increased, the arsenic content gradually increased. In the reduction environment zone, there was a decreasing trend in arsenic content in groundwater. The arsenic content in groundwater varied significantly with the seasons, and its dynamic characteristics were closely related to the water level. The arsenic content in groundwater decreased with the rise in groundwater level, and it responded obviously to the change of water level in the shallows. Overall, arsenic entered the groundwater from the solid phase through adsorption and desorption of exchangeable arsenic and exchangeable iron, and reductive dissolution of iron or manganese oxides bound iron in the medium during riverbank filtration.

Fluorescence technique for the characterization of natural organic matter in river water

2002 ◽  
Vol 46 (9) ◽  
pp. 117-125 ◽  
Author(s):  
U.K. Ahmad ◽  
Z. Ujang ◽  
Z. Yusop ◽  
T.L. Fong
Keyword(s):  
Organic Matter ◽  
River Water ◽  
Natural Organic Matter ◽  
Water Samples ◽  
Solid Phase ◽  
Complex Nature ◽  
Fluorescence Technique ◽  
Excitation Spectra ◽  
The Impact

The complex nature of natural organic matter (NOM), and the impact of this matter on drinking water quality have necessitated the characterization studies of NOM. A fluorescence technique for the characterization of NOM in Malaysian river water is reported. Water samples from several river sampling sites were collected and concentrated using a low-pressure reverse osmosis (LPROM). Solid phase extraction (SPE) using C18 extraction cartridges were used to fractionate the water samples into humic and non-humic fractions. To differentiate and classify various types of humic substances, fluorescence was applied in emission, excitation and in synchronous-scan modes. A synchronous spectral profile was found to be able to differentiate humic and fulvic acids better than the emission or excitation spectra. Synchronous excitation spectra showed different spectral patterns for the water samples due to different origin. All water samples showed the presence of both fulvic and humic acids.

Drug Induced Changes in Cell Organelles

1968 ◽  
Vol 26 ◽  
pp. 110-111
Author(s):  
Sarah A. Luse
Keyword(s):  
Clinical Medicine ◽  
Cell Organelles ◽  
Riboflavin Deficiency ◽  
Drug Induced ◽  
New Era ◽  
Health And Disease ◽  
In The Beginning ◽  
Cellular Pathology ◽  
Induced Changes ◽  
The Impact

In the mid-nineteenth century Virchow revolutionized pathology by introduction of the concept of “cellular pathology”. Today, a century later, this term has increasing significance in health and disease. We now are in the beginning of a new era in pathology, one which might well be termed “organelle pathology” or “subcellular pathology”. The impact of lysosomal diseases on clinical medicine exemplifies this role of pathology of organelles in elucidation of disease today.Another aspect of cell organelles of prime importance is their pathologic alteration by drugs, toxins, hormones and malnutrition. The sensitivity of cell organelles to minute alterations in their environment offers an accurate evaluation of the site of action of drugs in the study of both function and toxicity. Examples of mitochondrial lesions include the effect of DDD on the adrenal cortex, riboflavin deficiency on liver cells, elevated blood ammonia on the neuron and some 8-aminoquinolines on myocardium.

Effect of Glycosaminoglycans on Thrombin- and Atroxin-Induced Fibrin Assembly and Structure

1989 ◽  
Vol 62 (04) ◽  
pp. 1057-1061 ◽  
Author(s):  
Marcus E Carr ◽  
Patrick L Powers
Keyword(s):  
Chondroitin Sulfate ◽  
Fiber Diameter ◽  
Lag Phase ◽  
Low Molecular Weight ◽  
Fibrin Gels ◽  
Fiber Size ◽  
Induced Changes ◽  
The Impact ◽  
Fiber Radius ◽  
Turbidity Increase

SummaryThis study was performed to quantitate the impact of several glycosaminoglycans (GAG) on fibrin assembly and structure. Gel formation was monitored as the increase in optical density at 633 nm subsequent to thrombin (2 NIH u/ml) or atroxin (0.10 mg/ml) addition to solutions of buffered fibrinogen (1 mg/ml) or plasma. Gel absorbance was measured as a function of wavelength (400 to 800 nm) and gel fiber diameter and mass/length ratio (μ) were calculated. Chondroitin sulfate A (CSA)shortened the lag phase, enhanced the maximal rate of turbidity increase, and increased the final gel turbidity of fibrin gels formed by thrombin or atroxin. CSA (16 mg/ml) increased fiber μ from 1.3 to 3.1 × 1013 dalton/cm and fiber radius from 6.0 to 8.6 × 10-6 cm in thrombin-induced gels. μ increased from 0.7 to 2.7 × 1013 dalton/cm and fiber radius from 4 to 7.8 × 10-6 cm for atroxin-induced gels. Above 16 mg/ml, CSA caused fibrinogen precipitation in purified solutions but not in plasma. CSA inhibited thrombin-induced plasma clotting of plasma but effects in atroxin-mediated plasma gels paralleled those seen in purified solutions. Chondroitin sulfate B (CSB)-induced changes in fibrin were similar but slightly less dramatic than those seen with CSA. μ increased from 0.9 to 2.0 × 1013 dalton/cm for thrombin-induced fibrin gels and from 0.8 to 2.3 × 1013 dalton/cm for atroxininduced gels. Low molecular weight heparin (Mr = 5100) slowed fibrin assembly and reduced fiber size by 50% in thrombininduced gels. Changes in μ of atroxin-induced gels were much less pronounced (<20%). This study documents pronounced GAGinduced changes in fibrin structure which vary with GAG species and may mediate significant physiologic functions.

Development of Strategies for Glycopeptide Synthesis: An Overview on the Glycosidic Linkage

2020 ◽  
Vol 24 (21) ◽  
pp. 2475-2497
Author(s):  
Andrea Verónica Rodríguez-Mayor ◽  
German Jesid Peralta-Camacho ◽  
Karen Johanna Cárdenas-Martínez ◽  
Javier Eduardo García-Castañeda
Keyword(s):  
Chemical Synthesis ◽  
Solid Phase ◽  
Building Blocks ◽  
Heterogeneous Environments ◽  
Phase Synthesis ◽  
Low Concentrations ◽  
Biological Sources ◽  
Synthetic Routes ◽  
The Impact ◽  
Potential Use

Glycoproteins and glycopeptides are an interesting focus of research, because of their potential use as therapeutic agents, since they are related to carbohydrate-carbohydrate, carbohydrate-protein, and carbohydrate-lipid interactions, which are commonly involved in biological processes. It has been established that natural glycoconjugates could be an important source of templates for the design and development of molecules with therapeutic applications. However, isolating large quantities of glycoconjugates from biological sources with the required purity is extremely complex, because these molecules are found in heterogeneous environments and in very low concentrations. As an alternative to solving this problem, the chemical synthesis of glycoconjugates has been developed. In this context, several methods for the synthesis of glycopeptides in solution and/or solid-phase have been reported. In most of these methods, glycosylated amino acid derivatives are used as building blocks for both solution and solid-phase synthesis. The synthetic viability of glycoconjugates is a critical parameter for allowing their use as drugs to mitigate the impact of microbial resistance and/or cancer. However, the chemical synthesis of glycoconjugates is a challenge, because these molecules possess multiple reaction sites and have a very specific stereochemistry. Therefore, it is necessary to design and implement synthetic routes, which may involve various protection schemes but can be stereoselective, environmentally friendly, and high-yielding. This review focuses on glycopeptide synthesis by recapitulating the progress made over the last 15 years.

Polarographic and Voltammetric Determination of Trace Amounts of 3-Nitrofluoranthene

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1571-1587 ◽  
Author(s):  
Karel Čížek ◽  
Jiří Barek ◽  
Jiří Zima
Keyword(s):  
River Water ◽  
Solid Phase ◽  
Mercury Electrode ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Separation And Preconcentration

The polarographic behavior of 3-nitrofluoranthene was investigated by DC tast polarography (DCTP) and differential pulse polarography (DPP), both at a dropping mercury electrode, differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV), both at a hanging mercury drop electrode. Optimum conditions have been found for its determination by the given methods in the concentration ranges of 1 × 10-6-1 × 10-4 mol l-1 (DCTP), 1 × 10-7-1 × 10-4 mol l-1 (DPP), 1 × 10-8-1 × 10-6 mol l-1 (DPV) and 1 × 10-9-1 × 10-7 mol l-1 (AdSV), respectively. Practical applicability of these techniques was demonstrated on the determination of 3-nitrofluoranthene in drinking and river water after its preliminary separation and preconcentration using liquid-liquid and solid phase extraction with the limits of determination 4 × 10-10 mol l-1 (drinking water) and 2 × 10-9 mol l-1 (river water).

Introduction to geomicrobiology

2018 ◽  
Author(s):  
David L. Kirchman
Keyword(s):  
Fossil Fuels ◽  
Solid Phase ◽  
Direct Reduction ◽  
Iron Oxidation ◽  
Mineral Dissolution ◽  
Precipitation Process ◽  
Soluble Ions ◽  
Chemolithoautotrophic Bacteria ◽  
The Impact

Geomicrobiology, the marriage of geology and microbiology, is about the impact of microbes on Earth materials in terrestrial systems and sediments. Many geomicrobiological processes occur over long timescales. Even the slow growth and low activity of microbes, however, have big effects when added up over millennia. After reviewing the basics of bacteria–surface interactions, the chapter moves on to discussing biomineralization, which is the microbially mediated formation of solid minerals from soluble ions. The role of microbes can vary from merely providing passive surfaces for mineral formation, to active control of the entire precipitation process. The formation of carbonate-containing minerals by coccolithophorids and other marine organisms is especially important because of the role of these minerals in the carbon cycle. Iron minerals can be formed by chemolithoautotrophic bacteria, which gain a small amount of energy from iron oxidation. Similarly, manganese-rich minerals are formed during manganese oxidation, although how this reaction benefits microbes is unclear. These minerals and others give geologists and geomicrobiologists clues about early life on Earth. In addition to forming minerals, microbes help to dissolve them, a process called weathering. Microbes contribute to weathering and mineral dissolution through several mechanisms: production of protons (acidity) or hydroxides that dissolve minerals; production of ligands that chelate metals in minerals thereby breaking up the solid phase; and direct reduction of mineral-bound metals to more soluble forms. The chapter ends with some comments about the role of microbes in degrading oil and other fossil fuels.

A solid-phase extraction method that eliminates matrix effects of complex pulp mill effluents for the analysis of lipophilic wood extractives

2020 ◽  
Vol 35 (4) ◽  
pp. 577-588
Author(s):  
Sebastian España Orozco ◽  
Philipp Zeitlinger ◽  
Karin Fackler ◽  
Robert H. Bischof ◽  
Antje Potthast
Keyword(s):  
Solid Phase Extraction ◽  
Matrix Effects ◽  
Solid Phase ◽  
Internal Standard ◽  
Pulp Mill ◽  
Phase Extraction ◽  
Wood Extractives ◽  
Wood Extractive ◽  
Pulp Mill Effluents ◽  
The Impact

AbstractThe extraction of lipophilic wood extractives from pulp and paper process waters proves to be a challenging task, due to harsh and alternating process and sample conditions. This study has determined the potential use of polymeric sorbents for solid-phase extraction (SPE) and compared to classical silica-based reversed-phase packed columns, with polymeric hydrophilic-lipophilic balanced (HLB) cartridges being the sorbent with the most potential. Recovery functions were obtained with an internal standard mixture representative for the main lipophilic wood extractive groups, which are fatty acids and alcohols, sterols, sterol esters and triglycerides. The impact of pH, sample volume and sample matrix, expressed as TOC and cations, on the retention behavior of lipophilic extractives during SPE of industrial samples were determined with polymeric HLB sorbent. High variations in the composition of pulp mill matrices led to different optimal extraction conditions. Thus, a new SPE protocol was developed, which bypasses matrix interferences and omits the loss of analytes due to sample preparation. The method is applicable to different pulp mill effluents with large discrepancies in pH and sample matrices, resulting in recoveries >90 % with RSD <5 % for all lipophilic wood extractives.

scholarly journals Exogenous application of growth stimulators improves the condition of maize exposed to soil drought

2021 ◽  
Vol 43 (4) ◽  
Author(s):  
Agnieszka Ostrowska ◽  
Maciej T. Grzesiak ◽  
Tomasz Hura
Keyword(s):  
Plant Growth ◽  
Developmental Stages ◽  
Aminolevulinic Acid ◽  
Stem Elongation ◽  
Development Stage ◽  
Photochemical Activity ◽  
Soil Drought ◽  
Beneficial Effects ◽  
Induced Changes ◽  
The Impact

AbstractSoil drought is a major problem in plant cultivation. This is particularly true for thermophilic plants, such as maize, which grow in areas often affected by precipitation shortage. The problem may be alleviated using plant growth and development stimulators. Therefore, the aim of the study was to analyze the effects of 5-aminolevulinic acid (5-ALA), zearalenone (ZEN), triacontanol (TRIA) and silicon (Si) on water management and photosynthetic activity of maize under soil drought. The experiments covered three developmental stages: three leaves, stem elongation and heading. The impact of these substances applied during drought stress depended on the plant development stage. 5-ALA affected chlorophyll levels, gas exchange and photochemical activity of PSII. Similar effects were observed for ZEN, which additionally induced stem elongation and limited dehydration. Beneficial effects of TRIA were visible at the stage of three leaves and involved leaf hydration and plant growth. A silicon preparation applied at the same developmental stage triggered similar effects and additionally induced changes in chlorophyll levels. All the stimulators significantly affected transpiration intensity at the heading stage.

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