Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

and oats (Avena sativa) had significantly higher Pb concentrations after 3 months of growth
compared to plants grown at pH 6.4 (Allinson and Dzialo, 1981).
Invertebrates
The uptake of Pb into invertebrates depends on the physical environment and parameters
such as pH, calcium concentration, organic matter content, and CEC. Greater accumulation is
found generally when the soil pH or organic content is lower (U.S. Environmental Protection
Agency, 1986a).
Soil pH has a significant influence on uptake of Pb into invertebrates. Perämäki et al.
(1992) studied the influence of soil pH on uptake into the earthworm Aporrectodea caliginosa.
Lead accumulation was lowest at the highest pH values, but there was no statistical difference
due to variability in the data. Variability in the response also was found by Bengtsson et al.
(1986), who reared earthworms (Dendrobaena rubida) in acidified soils at pH 4.5, 5.5, or 6.5.
Lead uptake into worms was pH-dependent, although the highest concentrations were not always
found at the lowest pH. There was no clear relationship between Pb concentration in cocoons
and soil pH, and Pb concentrations were higher in the hatchlings than in the cocoons. As has
been reported in many other studies (Neuhauser et al., 1995), concentration factors (ratio of Pb in
worm to Pb in soil) were lower at higher Pb concentrations in soil. The authors attribute some of
this to a lowered feeding activity in worms at higher Pb concentrations (Bengtsson et al., 1986).
Beyer et al. (1987) and Morgan and Morgan (1988) recognized that other factors beyond
soil pH could influence the uptake of Pb into earthworms, which may be the cause of the
inconsistencies reported by several authors. Both studies evaluated worm uptake of Pb relative
to pH, soil calcium concentration, and organic matter content. Morgan and Morgan (1988) also
considered CEC, and Beyer et al. (1987) considered concentrations of phosphorus, potassium, or
magnesium in soil. Both studies found that calcium concentrations in soil were correlated with
soil pH. Morgan and Morgan (1988) also found that CEC was correlated with percentage
organic matter. Soil pH (coupled with CEC) and soil calcium were found to play significant
roles in the uptake of Pb into worms (Beyer et al., 1987; Morgan and Morgan, 1988). Beyer
et al. (1987) noted that concentrations of phosphorus in soil had no effect.
AX7-52