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

variables, it does not imply causation of effects. The following studies suggest an association
between Pb concentration and an alteration of community structure and function (see summary
in Table AX7-2.6.2):
Reduced Primary Productivity and Respiration
Jayaraj et al. (1992) examined the effects of Pb on primary productivity and respiration in
an algal community of two water bodies. Concentrations of Pb in water (6 to 80 mg/L) were
found to significantly reduce primary productivity and increase respiration. The authors
suggested that increased respiration indicated a greater tolerance to or adaptive mechanisms of
the resident heterotrophs to cope with lead stress.
Alterations of Community Structure
Deacon et al. (2001) studied a macroinvertebrate community in mine-affected waters of
Colorado. Initially, transplanted bryophytes were used to assess whether metals could
bioaccumulate at various mine-affected and unaffected sites (Deacon et al., 2001; Mize and
Deacon, 2002). Lead was bioaccumulated by the bryophytes, and median tissue concentrations
at mine-affected sites (34 to 299 μg/g dw) were higher than at reference sites (2.5 to 14.7 μg/g
dw). Lead concentrations in surface water and sediment ranged from