ILLINOIS POLLUTION CONTROL BOARD
    April
    14,
    1971
    PHOSPHATE WATER STANDARDS
    Supplemental opinion
    (Samuel
    R.
    Aldrich, Board Member)
    There are a
    few sections of
    the opinion with which
    I do not concur.
    Page
    1.
    Rate of phosphorus inputs
    The opinion states that man’s activities including agriculture
    have greatly increased nutrient additions to the lake. This is not
    supported by studies by the Illinois State Geological
    Survey of
    bottom sediments in southern Lake Michigan.
    The
    top
    1
    inch or
    less
    of bottom deposits averages no higher in phosphorus
    than
    the
    layer immediately below or of several other more deeply buried
    layers representing deposits many
    thousands:rof years old.
    If
    the sewage from Chicago were being discharged into Lake Michigan,
    which it is not,
    the phosphorus
    input would
    be very large
    indeed.
    It is my opinion that, with the possible exception of increased
    animal wastes,
    the introduction of agriculture has b~adlittle
    effect on the phosphorus available for accelerated eutrophication.
    When grass,
    leaves,
    and weeds are
    left entirely on the surface as
    in the virgin condition,
    soluble organic phosphorus compounds
    resulting from decay are more likely to be carried off into surface
    waters than when crop residues are incorporated into the soil
    through farming practices.
    I feel that this explains
    the unex-
    pected concentrations of phosphorus
    in bottom sediments previously
    described.
    Page
    9.
    The proper method for determining phosphorus
    in water.
    The opinion states that total rather than filterable phosphorus
    is the proper method to assess potential for eutrophication.
    I
    agree
    that this is the correct method for Lake Michigan.
    Filterable
    phosphorus by itself fails to measure
    the phosphorus
    that is tempo-
    rarily bound w±thinthe tissues of living and dead organisms in-
    cluding higher plantsthat
    are
    in suspension and
    thus included in
    the water sample.
    There
    is,
    of course,
    an additional reserve in
    1±eform of dead plant residues
    and phosphorus loosely held
    in
    bottom deposits.
    1
    —
    475
    Total phosphorus
    is not
    a suitable measurement on the streams of
    Illinois in which there
    is an appreciable amount of suspended soil
    particles.
    Much of the phosphorus that is associated with soil
    particles
    is unavailable or only very slowly released into water.
    Although this subject urgently needs additional research,
    it
    appears likely that
    a given amount of phosphorus attached to soil
    particles will support only
    1/4 to 1/7
    as much algal biomass growth
    as the same amount of phosphorus
    in soluble phosphorus compounds
    (R.
    M. Gerhold and J.
    E, Thompson,
    1969).
    Several
    soil scientists who are authorities on phosphate chemistry
    suggest that soil sediment-associated phosphorus
    is
    10 to
    30 percent
    as available for supporting eutrophication as phosphorus
    in solution.
    /
    Samuel
    R~ Aldrich
    Membek~, IlIi~ó±sPollutiOn Cox~trolBoard
    I,
    Regina E,
    Ryan,
    Clerk of
    the Illinois Pollution Control Board
    certify that Dr.
    Samuel
    R. Aldri~hs~ii~itted
    the ~o~v~opinion
    on
    14
    of
    J~oril
    1971.
    ution Control Board
    1
    —
    476

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