1986-12-08_GENERAL DOCUMENTS - M1977493 ‎(2)‎

• Permit No: M1977493
• IBM Index Class Name: GENERAL DOCUMENTS
• Doc Date: 12/8/1986
• Doc Name: METHODS AND COSTS FOR STABILIZING FINE-SIZED MINERAL WASTES
• From: DEPARTMENT OF THE INTERIOR
• To: DRMS
• Media Type: D
• Archive: No

15
organic-free effluent and one containing all the organic flotation reagents ; I
used in the mill but no salts. Water hyacinths were used as the test plant.
Hyacinths in the artificial organic-bearing solution thrived for several weeks liI,,�''
with no visible harm. Plants in mill effluent or in the artificial saline {
with sufficient inorganic salts added to produce an osmotic concentra-
solutions
Lion comparable to the effluent mill water wilted immediately. The measured
♦ osmotic concentrations of the two saline solutions were 2.36 and 2.46 atmos-
rI
pheres. The osmotic gradient between the plant fluids and the environment
4 around the roots presumably dehydrated the plants. A control test was run in
which a hyacinth was placed in a nonreactive mannitol solution having an j.
osmotic concentration of 2.4 atmospheres. The hyacinth wilted as rapidly as io
that death of the test plants was due more to
in the mill effluent, indicating
i
- . the salt content than to either toxic organic compounds or metallic elements. � �i'.��a`i
} The principal salt in the mill effluents is sodium. chloride, but testing indi-
cates that dehydration is produced with all types of salts at the osmotic con- ii ` i
=: centrations considered.
To determine the effect of salinity on germination, tomato seeds we0r�o
q.
t treated with mannitol solutions at osmotic concentrations ranging from +
5 atmospheres in increments of 0.5 atmosphere. The germination rate dropped
ill•.:.:
with increasing concentration until there was almost no germination at i+., ,
4.5 atmospheres. In other tests, seeds of several species were planted in
' copper tailings containing sufficient salts to produce osmotic concentrations ;
between 2.2 and 2.5 atmospheres. These tests indicated that such osmotic con-
f centrations will not materially hinder initial germination of most plants, but s
will limit growth unless the tailings are leached to remove the soluble salts. ;
Effect of Heavy Metal Salts on Seed Germination
Plant growth tests made in tailings, containing 0.07 and 0.2 percent ,�• lit
� t
copper in the form of sulfide minerals , indicated that copper in the sulfide
form was not immediately deleterious. To ascertain how much soluble metal
salts could be tolerated, copper, nickel, zinc, and composite salts of these
elements were added to test plots and tomato seeds planted. Tomato was used I '
as a relatively quick growing criterion plant of above medium salt tolerance
(EC, x 103 - 10) that is relatively sensitive to heavy metal phytotoxicants.
Tomato was selected for these tests in that it has a salt tolerancy similar I
to many of the forage plants being used for vegetative stabilization such as
alfalfa, tall fescue, rye, wheat, orchardgrass , etc. These tests showed that
1,000 ppm copper had little effect, nickel concentrations above 100 ppm were !
toxic , and zinc concentrations above 10 ppm were toxic. When using a compos-
ite of these elements, toxic effects became evident at 10 ppm and became pro-
nounced at about 100 ppm. The effect achieved with the low concentrations
tested indicate toxicity to be independent of osmotic pressure.
Interactions of Fertilizers and Heavy Metal Minerals
l
.. Contradictory results were derived from initial tests wherein nitrogen, F
phosphorus, and potassium fertilizers were added to test plots of copper flo-
tation tailings from different mills. Addition of fertilizers enhanced germi-
nation and growth on some tailings , whereas the opposite effect was achieved
4
f