RE: Radionuclides in "Green Sand"-Are there any?

["Jim Otton" <jkotton@usgs.gov>]

Dale and Radsafers,



"Greensand" is a natural mineral commodity comprised of the mineral

glauconite mixed with other clays and quartz sand in varying proportions.

Glauconite is a dull-green, amorphous, granular to earthy mineral of the

mica group.  It is noted for its capabilities to filter minor (iron and

manganese, for example) and trace elements (arsenic and radium, for example)

from water and thus greensand was used in many of the early water filtration

systems.  Presently, greensand filtration systems are often enhanced with

potassium permanganate (a strong oxidizing chemical) or ground anthracite to

increase the filtration function or to solve filter fouling problems.  The

chemical formula for glauconite includes potassium as a significant, but

variable, component.  However glauconite is almost always found in reduced

marine sediments, an environment where phosphate minerals can also occur.

Wherever marine phosphate minerals are present, enhanced levels of uranium

are also present.  Thus an additional possibility for radionuclides in

greensand may be the co-occurrence of uraniferous phosphatic material in the

sand.  Using uraniferous greensand in a filter could result in the release

of uranium or any of its decay products to the filtered water.  Finally,

radium is readily filtered by greensand filters.  If the water entering the

filitration system has sufficient levels of radium, then buildup of radium

on the filters may lead to increased radium decay product levels in the

filtered water.  It would be helpful to know if the radionulcide problem

only occurs after the filters have been in place for a long time.



Without knowing what the source of the radioactivity is, it is difficult to

know what changes in the treatment regimen may lower the radioctivity of the

filtered water.  EPA has a webpage document that describes greensand filters

and some of the problems (pH, biofouling, etc.) associated with their use.

Careful reading of that document may suggest other possibilities for

radionuclides in the filtered water.



Jim Otton

U.S. Geological Survey



-----Original Message-----

From: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu]On Behalf Of Dale Dusenbury

Sent: Thursday, June 03, 2004 3:09 PM

To: radsafe@list.vanderbilt.edu

Cc: alan.hardy@ncmail.net; Dale Dusenbury

Subject: Radionuclides in "Green Sand"-Are there any?





My name is Dale Dusenbury and I am an environmental radiation specialist

with the North Carolina Radiation Protection Section. Does anyone have

any information on the presence of  radionuclides( particularly natural

ones),  found in "green sand", a filtering media used in water

purification plants? This is the definition I found on the web for green

sand:"/Greensand is a mineral mined from natural deposits of glauconite.

These deposits are composed primarily of iron-potassium silicate. ... A

great source of potassium and other trace elements."  /Is this natural

greensand used primarily or is there a synthetic substitute for water

purification purposes?

There is a question at a ground water supply in our area due to levels

of natural nuclides in water that appear to increase following treatment

by "green sand". If such nuclides are present in this material, what ph

or other conditions(water hardness from manganese or iron from example)

could move these nuclides into solution where they could enter the

treated water? Radsafers are welcome to reply to the list or to my

e-mail if you like.

Dale Dusenbury, CHP, MSPH

NC Radiation Protection Section

3825 Barrett Drive

Raleigh, NC 27609-7221

e-mail:dale.dusenbury@ncmail.net







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