1987-01-08_REVISION - M1977493 - Laserfiche WebLink

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15 ,; ',~i organic-free effluent and one containing all the organic flotation reagents used in the mill but no salts. Water hyacinths were used as the test plant, {{yacinths in the artificial organic-bearing solution thrived for several weeks With no visible harm. Plants in mill effluent or in the artificial saline solutions with sufficient inorganic salts added to produce an osmotic concentra- } tion comparable to the effluent mill water wilted immediately, The measured •~ osmotic concentrations of the two saline solutions were 2.36 and 2.46 atmos- pheres. The osmotic gradient between the plant fluids and the environment i 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 osmotic concentration of 2..4 atmospheres. The hyacinth wilted as rapidly as j in the mill effluent, indicating that death of the test plants was due more to the salt content than to either toxic organic compounds or metallic elements. " 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- =s centrations considered, ~ To determine the effect of salinity on germination, tomato seeds were ~ treated with mannitol solutions at osmotic concentrations ranging from 0 to S atmospheres in increments of 0.5 atmosphere, The germination rate dropped with increasing concentration until there was almost no germination at 4.5 atmospheres. In other tests, seeds of several species were planted in t' copper tailings containing sufficient salts to produce osmotic concentrations I between 2.2 and 2.5 atmospheres. These tests indicated that such osmotic con- ~ centrations will not materially hinder initial germination of most plants, but ' will limit growth unless the tailings are leached to remove the soluble salts, t Effect of Heavy Metal Salts on Seed Germination ' Plant growth tests made in Lailings, containing 0.07 and 0.2 percent r 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 i elements were added to test plots and tomato seeds planted. Tomato was used a; as a relatively quick growing criterion plant of above medium salt tolerance ' (ECG k l0a = 10) that is relatively sensitive to heavy metal phytotoxicants. Tomato was selected for these tests in that it has a salt tolerancy similar to many of the forage plants being used for .vegetative stabilization such as alfalfa, tall fescue, .rye, wheat, orchardgrass, etc. These tests showed [hat 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- pounced at about 100 ppm. The effect achieved with the low concentrations tested indicate toxicity to be independent of osmotic pressure. r"l Interactions of Fertilizers and Heavy Metal Minerals ;: `': t ' ~i .;~: ,~' I.i i77 r` ' 1 ' re. ~, w ~.:: . ,;, ~; ; ;, ;~ is>6 I !:~ ~' 'i~ •~: ~'~ i.< , iii yd{~}t: ' ~~ ~j7 4 ~~ :: ;i. ~: ~:~ c:~ ili ~,~ i~ t :; j3 r ` ' ~:~ I;, t, .. i'_` p S Iii .. A- 'pt .1 'I i Contradictory results were derived from initial tests wherein nitrogen, ~ phosphorus, and potassium fertilizers were added to test plots of copper flo- tation tailings from different mills. Addition of fertilizers enhanced germs- nation and growth on some tailings, whereas the opposite effect was achieved + I ~__ ~ t