Podrobnosti záznamu

Název
    Arsenic enrichment in groundwater of the alluvial aquifers in Bangladesh : an overview
Údaj o odpovědnosti
    K. Matin Ahmed, Prosun Bhattacharya, M. Aziz Hasan, S. Humayun Akhter, S.M. Mahbub Alam, M.A. Hossain Bhuyian, M. Badrul Imam, Aftab A. Khan, Ondra Sracek
Další názvy
    Arsenic in groundwater of sedimentary aquifers (Variant.)
Autor
    Ahmed, K. Matin
    Akhter, S. Humayun
    Alam, S.M. Mahbub
    Bhattacharya, Prosun
    Bhuyian, M. A. Hossain
    Hasan, M. Aziz
    Imam, M. Badrul
    Khan, Aftab A.
    Šráček, Ondřej
Jazyk
    anglicky
Zdrojový dokument - seriál
    Applied geochemistry
Svazek/č.
    Vol. 19, no. 2
Strany
    p. 181-200
Rok
    2004
Poznámky
    12 obr.
    Bibliografie na s. 198-200
    il.
    Zkr. název ser.: Appl. Geochem.
Klasifikační znak
    504.4
    628.19
Skupina konspektu
    504
    626/627
Předmětová skupina
    arzén
    delta
    fosfor
    holocén
    hydrochemie
    jíl
    litofacie
    mobilizace
    oblast snosová
    písek
    voda podzemní
    záplavová niva
    znečištění
    zvodnělý kolektor aluviální
    železo
Geografické jméno
    Bangladéš
Klíčové slovo
    Alluvial
    Aquifers
    Arsenic
    Bangladesh
    Enrichment
    Groundwater
    Overview
Abstrakt (anglicky)
   Arsenic in the groundwater of Bangladesh is a serious natural calamity and a public health hazard. Most groundwater from the shallow alluvial aquifers (<150 m), particularly in the Holocene plain lands, are vulnerable to As-enrichment. Delta plains and flood plains of the Ganges-Brahmaputra river system are moderately to severely enriched and more than 60 per cent of the tube wells are affected. Shallow aquifers in the Meghna river basin and coastal plains are extremely enriched with more than 80 per cent of the tube wells affected. Aquifers in the Pleistocene uplands and Tertiary hills are low in As. The vertical lithofacies sequence of the sediments from highly enriched areas of the country show two distinct lithofacies associations-a dominantly sandy channel-fill association and a fine-grained over bank association. The sediments can be grouped into 4 distinct lithofacies, viz. clay, silty clay, silty sand and sand.
   Thin section petrography of the As-enriched aquifer sands shows that the sands are of quartzolithic type and derived from the collision suture and fold thrust belt of the recycled orogen provenance. Groundwater is characterized by circum-neutral pH with a moderate to strong reducing nature. The waters are generally of Ca-Mg-HCO3 or Ca-Na-HCO3 type, with HCO3- as the principal anion. Low SO4-2 and NO-3, and high dissolved organic C (DOC) and NH+4 concentrations are typical chemical characteristics of groundwater. The presence of dissolved sulfides in these groundwaters indicates reduction of SO4. Total As concentration ín the analyzed wells vary between 2.5 and 846 ug 1-1 with a dominance of As(III) species (67-99per cent). Arsenic(III) concentrations were fairly consistent with the DOC and NH+4 contents. The HNO3 extractable concentrations of As (AsNo3) in the sediments (0.5-17.7 mg kg-1), indicate a significant positive correlation with FeNO3, MnNO3, AlNO3 and PNO3.
   The concentrations of SNO3, (816-1306 mg kg-1) peaked in the clay sediments with high organic matter (up to 4.5 wt.per cent). Amounts of oxalate extractable As (Asox) and Fe (Feox) ranged between 0.1-8.6 mg kg-1 and 0.4-5.9 g kg-1, respectively. Arsenic OX was positively correlated with Feox, Mnox and Alox in these sediments. Insignificant amounts of opaque minerals (including pyrite/arsenopyrite) and the presence of high As contents in finer sediments suggests that some As is incorporated in the authigenically precipitated sulfides in the reducing sediments. Moreover, the chemical extractions suggest the presence of siderite and vivianite as solid phases, which may control the aqueous chemistry of Fe and PO43-. Reductive dissolution of Fe oxyhydroxide present as coatings on sand grains as well as altered mica (biotite) is envisaged as the main mechanism for the release of As into groundwater in the sandy aquifer sediments
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    28. 3. 2008
Datum importu
    8. 8. 2012