At pH values below 4.5 solubility rapidly increases, causing aluminum concentrations to rise above 5 ppm. This may also occur at very high pH values.
Dissolved Al3+-ions are toxic to plants; these affect roots and decrease phosphate intake. As was mentioned above, when pH values increase aluminum dissolves. This explains the correlation between acid rains and soil aluminum concentrations. At increasing nitrate deposition the aluminum amount increases, whereas it decreases under large heather and agricultural surfaces. In forest soils it increases.
Aluminum is not a dietary requirement for plants, but it may positively influence growth in some species. It is taken up by all plants because of its wide distribution in soils. Grass species may accumulate aluminum concentrations of above 1% dry mass.
Acid rain dissolves minerals in soils, and transports these to water sources. This may cause aluminum concentrations in rivers and lakes to rise.
Aluminum naturally occurs in waters in very low concentrations. Higher concentrations derived from mining waste may negatively affect aquatic biocoenosis. Aluminum is toxic to fish in acidic, unbuffered waters starting at a concentration of 0.1 mg/L. Simultaneous electrolyte shortages influence gull permeability, and damage surface gull cells. Aluminum is mainly toxic to fish at pH values 5.0-5.5. Aluminum ions accumulate on the gulls and clog these with a slimy layer, which limits breathing. When pH values decrease, aluminum ions influence gull permeability regulation by calcium. This increases sodium losses. Calcium and aluminum are antagonistic, but adding calcium cannot limit electrolyte loss. This mainly concerns young animals. An aluminum concentration of 1.5 mg/L turned out to be fatal to trout. The element also influences growth of freshwater bony fish.
Phytoplankton contains approximately 40-400 ppm aluminum (dry mass), which leads to a bioconcentration factor of 104-105 compared to seawater.
Read more:
http://www.lenntech.com/periodic/water/ ... z1viJXOOnK