Elevated Aluminum Concentrations Research Articles

Origin and resolution of the aluminum controversy concerning Alzheimer’s neurofibrillary degeneration

Elevated concentrations of aluminum are found in regions of neurofibrillary change in brains with senile or presenile dementia of Alzheimer's type. The concentrations of aluminum found in the human disease are comparable to those found in experimental animals with aluminum-induced neurofibrillary degeneration (NFD). Although there are a number of reports confirming these observations, two laboratories have been unable to detect elevated levels in Alzheimer's disease. We conducted an interlaboratory study to resolve this discrepancy and traced the discrepancy to difficulties in analytical procedures. We concluded that failure to detect elevated aluminum levels associated with NFD is the result of (a) lack of strict adherence to the criteria for sample selection; (b) selection of too large a sample for analysis; and (c) use of analytical methodology that has potential matrix interference for the measured signal.

Application of neutron activation analysis in acid precipitation studies

Instrumental neutron activation analysis has been successfully employed in three distrinct acid precipitation studies. These include the determination of ten (Al, Br, Ca, Cl, Cu, I, Mg, Mn, Na and V) elements in urban rainfall, elevated aluminum concentrations in acidified lakes and major ions (Ca, Cl, K, Mg and Na) in small-mouth bass kept in controlled pH environments. Quality control was assured by analyzing two certified standard reference materials prepared by the National Bureau of Standards (NBS 1643a) and National Research Council of Canada (hepatopancreas TORT-1 marine biological tissue).

Biomass and compositional changes in the periphytic community of an artificial stream in response to lowered pH

Two artificial streams simulating low-order, softwater streams of the Upper Peninsula of Michigan were employed to examine the effects of lowered pH on periphytic algae. The control stream contained water with a circumneutral pH whereas the pH of the water in the acidified stream was decreased to pH 4 with H2SO4. Chlorophyll a concentrations and cell densities in the periphytic algal communities were used to measure differences in biomass accumulations between the 2 streams over a 42-d, spring colonization period. Relative abundances of algal genera and Stander's similarity index (SIMI) were used to examine compositional differences between the control and acidified periphytic algal communities. These algal communities exhibited pronounced differences in their total biomasses and compositions indicating periphytic algal communities inhabiting low-order, softwater streams, such as those of the Upper Peninsula of Michigan, are vulnerable to acidic deposition. Decreased biomass accumulation under acidified conditions was believed to result primarily from decreased nutrient availability, and possibly secondarily from elevated aluminum and/or iron concentrations. The shift in community compositions was interpreted to be a more direct response to the lowered pH as acidophils and acid tolerant genera became favored, and thus more abundant.

The effects of low pH, low calcium concentrations and elevated aluminium concentrations on sodium fluxes in brown trout, Salmo Trutta L.

The effects of pH (c. 7.0, 5.4, 4.5 and 4.0), nominal Al levels (0 and 8 μmol L−1) and Ca levels (10 and 50 μmol L−1) on Na influx, efflux and netflux of brown trout have been investigated using artificial lake water of known composition. Low pH had little effect on influx, but tended to increase efflux, particularly in the low Ca treatments. A nominal addition of 8 μmol Al L−1 at pH 4.5 and 4.0 reduced influx significantly. Efflux was unaffected. Aluminium addition at pH c. 7.0 and 5.4 had no such effect. The measured Al concentrations at the end of the static 8 hr flux measuring experiments were markedly lower than the nominal amount of A1 added to the start.

The impact of depressed pH and elevated aluminum concentrations on specific dynamic action in Somatochlora cingulata (De selys)

Differences in oxygen consumption attributable to apparent specific dynamic action (SDA) were measured in relation to feeding level in the dragonfly naiad Somatochlora cingulata exposed to low pH and sublethal aluminum concentration plus low pH. The average increases in respiration among the treatments following feeding were 50–60% that of controls. The average treatment peak height ratios (post/prefeeding respiration rates) were proportionately reduced and not significantly different from the average controls indicating that the resting metabolism, rather than SDA, was reduced.

Aluminum speciation and equilibria in soil solutions of a Haplorthod in the Adirondack Mountains (New York, U.S.A.)

Aluminum chemistry was evaluated in throughfall and leachates from O-, E- and B-horizons of a Spodosol (Typic Haplorthod) at hardwood and conifer sites in the Adirondack Mountains, New York. Organic and fluoride complexes were the dominant forms of aluminum in all soil solutions and throughfall, whereas sulfate and hydroxide complexes were less prevalent. Aquo-aluminum concentrations were extremely low in O-horizon leachates (6 and 7% of total inorganic aluminum at conifer and hardwood sites, respectively), and increased to 28 and 26% of total inorganic aluminum in solutions from B-horizons at conifer and hardwood sites, respectively. Acid-soluble aluminum was 51 and 54% of total aluminum in O-horizon leachates at the conifer and hardwood sites, respectively, and 88% of total aluminum in throughfall. Like aqueous aluminum, soil-bound aluminum was largely associated with organic matter. Solutions were generally undersaturated with respect to the solubility of aluminum-sulfate and aluminum-hydroxide mineral phases. Elevated concentrations of organic and non-labile aluminum in forest floor solutions suggest that biocycling by vegetation may be an important mechanism of aluminum transport in forest ecosystems.

Trace element concentrations in hair, fingernails and plasma of patients with chronic renal failure on hemodialysis and hemofiltration.

Trace element concentrations in hair and fingernails and plasma of nondialyzed, hemodialyzed and hemofiltered patients with chronic renal failure and healthy volunteers were measured by atomic and flameless atomic absorption spectrophotometry and neutron activation analysis. Plasma aluminum concentrations in all three groups of patients were higher than in the controls. Aluminum levels in plasma and red blood cells were higher in hemofiltered patients than in dialyzed patients. The aluminum concentrations in the hair of both nondialyzed and dialyzed patients was higher than in the controls, while that in the hemofiltered patients it was not. These elevated aluminum concentrations appear to be mainly caused by the use of aluminum-contaminated dialysate. Calcium concentrations in the hair of nondialyzed and dialyzed patients were higher than in the controls. Plasma zinc concentrations in all the patients were lower than the controls, and the concentrations in hemofiltered patients were lower than in the dialyzed patients.

Effect of calcium and aluminum concentrations on the survival of brown trout (Salmo trutta) at low pH.

Experimental evidence suggests that the two most important ions with respect to survival of fish at low pHs are calcium (BROWN 1981, 1982a and b; BROWN and LYNAM 1981) and aluminium (SCHOFIELD and TROJNAR 1980; BAKER and SCHOFIELD 1980, 1982). A minimal concentration of the former ion is necessary for survival, and in general, elevated concentrations of aluminium reduce survival. These same two ions are also clearly important in the field because acid lakes in Europe and North America have typically low concentrations of calcium and high concentrations of aluminium (WRIGHT et al. 1980). The only published experimental study of the combined effects of low calcium and elevated aluminium concentrations on fish at low pH shows that the rate of loss of plasma chloride at pH 5.3 and 5.5 in solutions containing 0.9 mg 1 -I of aluminium is higher when they contain 0.8 mg 1 -I of calcium compared with solutions containing 3.0-4.2 mg 1 -I of calcium (MUNIZ AND LEIVESTAD 1980). In this paper, the results of experiments to determine the survival times of yolk sac fry of brown trout (Salmo trutta) in a range of pHs, calcium and aluminium solutions are described, and the relevance of the results to the field situation is also discussed. METHODS AND MATERIALS

Aquatic Invertebrates from the Smoking Hills, N.W.T.: Effect of pH and Metals on Mortality

Experiments were conducted on planktonic crustaceans and insect larvae from acidic and alkaline tundra ponds at the Smoking Hills, N.W.T. to determine their tolerance to low pH and elevated levels of potentially toxic elements, including Al. The crustaceans (Daphnia middendorffiana, Diaptomus arcticus, Lepidurus arcticus, Branchinecta paludosa), which are found only in alkaline ponds, died rapidly below pH 4.5. The insect larvae (Orthocladius consobrinus and Limnephilus pallens) from the same alkaline ponds were able to survive for extended periods at pH 3.5, though they do not occur in acidic waters at the Smoking Hills. The red chironomid (Chironomus riparius) is restricted to acidic ponds although it was able to survive not only at pH 2.8, but also in pond water of pH 8.2.Water from an acidic pond (pH 2.8) was markedly more toxic to crustaceans than water from an alkaline pond (pH 8.2) when both were adjusted to pH 4.5. Elevated concentrations of aluminum may account for this additional toxicity of the acidic pond water. Levels reached 20 mg/L Al, and in experiments with Al, additions to the alkaline waters and to the acidic pond waters, after metal removal, caused toxicity to the crustaceans.The absence of crustaceans from acidic ponds at the Smoking Hills may be due to their extreme sensitivity to low pH. The similarly restricted distribution of certain of the insect larvae, in contrast, cannot be explained this simply. Metal concentrations in acidic ponds impose an added stress. Aluminum was found to be the key additional factor to that of H+ ion concentration.Key words: acidic ponds, tundra ponds, Smoking Hills, bioassays, zooplankton, insect larvae, crustaceans, Daphnia, Diaptomus, Lepidurus, Brachinecta, Chironomus, Orthocladius, Limnephilus, heavy metals, aluminum, calcium, sodium, iron, zinc, nickel