• ES Picture of the Day 22 2020

    From Black Panther@21:1/186 to All on Sun Nov 22 11:00:28 2020
    EPOD - a service of USRA

    The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
    captions and links exemplifying features within the Earth system. The
    community is invited to contribute digital imagery, short captions and
    relevant links.


    Archive - Acid Mine Drainage Chemistry

    November 21, 2020

    Acidminedrainagea copy

    Every weekend we present a notable item from our archives. This EPOD
    was originally published November 21, 2003.

    Provided and copyright by: Enver Murad, Bayerisches
    Geologisches Landesamt
    Summary author: Enver Murad

    Pyrite (iron sulfide) is a common constituent of lignites and coals.
    This pyrite oxidizes as it is exposed to the atmosphere in the course
    of mining, leading to the generation of sulfuric acid and dissolved
    iron (acid mine drainage). Besides the detrimental effect that the
    acidity has on the environment, this process often leads to an
    extensive generation of ochreous precipitates.

    In the example shown here, waters draining a sulfide-rich lignite seam
    in the Czech Republic precipitate under different conditions.
    Initially, a bright orange precipitate, consisting mainly of the
    sulfate-containing mineral schwertmannite, forms under acid conditions.
    After merging with alkaline waters (entering from the right-center of
    the picture), iron that has remained in solution precipitates almost
    instantaneously as ferrihydrite, a poorly-crystalline, sulfate-free
    iron oxyhydroxide, leading to a sudden change of precipitate color to
    reddish-brown. The variations in color can thus serve as indicators for
    the precipitate composition, and thereby for the conditions under which
    the precipitates formed.

    For more information on this locality, see the article by Murad and
    Rojík in American Mineralogist vol. 88, 2003, pp. 1915-1918


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  • From Black Panther@21:1/186 to All on Tue Dec 22 11:00:38 2020
    EPOD - a service of USRA

    The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
    captions and links exemplifying features within the Earth system. The
    community is invited to contribute digital imagery, short captions and
    relevant links.


    Cardinals’ Fall Friend

    December 22, 2020

    Bayside Cardinal shelling sunflower seeds

    Photographer: Rob Sheridan
    Summary Author: Rob Sheridan

    Although it will deign to consume the occasional insect or fruit,
    the Northern Cardinal ( Cardinalis cardinalis) is a prolific
    eater of grain. During mating season, males will entice females with
    choice kernels presented beak-to-beak. Late in the summer, their
    attention turns to newly mature and highly nutritious sunflower
    seeds. However, reaching the nutritious nutmeat requires removing the
    tough outer hull. This is difficult to do without hands, but the
    Northern Cardinal succeeds with only its blunt beak and tongue as
    illustrated by this bright red male as it stakes out a productive
    sunflower head. Photo taken November 26, 2019.
    * Squantum, Massachusetts Coordinates: 42.29482, -71.0104

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    Earth Science Picture of the Day is a service of the
    -
    Universities Space Research Association.

    https://epod.usra.edu

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