Kr. Sistani et al., EVALUATION OF 4 CHEMICAL EXTRACTANTS FOR METAL DETERMINATIONS IN WETLAND SOILS, Communications in soil science and plant analysis, 26(13-14), 1995, pp. 2167-2180
Wetland soils (hydric soils) are unique in their chemical characterist
ics compared to upland soils. It is known that they are capable of rem
oving a variety of wastes from polluted water entering the wetland inc
luding metals and potentially toxic heavy metals. When these metals ar
e determined in wetland soils, it is necessary to use the proper chemi
cal extractant(s). Four commonly used chemical extractants (Mehlich 1,
Mehlich 3, 0.1M HCl, and DTPA) for soil fertility evaluation were sel
ected to measure metal concentrations of three different wetland soils
/spoils. Soil samples were collected from the constructed wetland cell
s which were lined with Abernathy silt loam topsoil and two different
mine spoil materials [collected from active coal strip-mined sites in
Alabama (pH 5.9) and Tennessee (pH 3.2)]. Mehlich 3 extracted the most
zinc (Zn), iron (Fe), manganese (Mn), calcium (Ca), magnesium (Mg), p
otassium (K), sodiumm (Na), and aluminum (Al), while 0.1M HCl extracte
d more cadmium (Cd), copper (Cu), and lead (Pb). Extractants followed
the same trend in removing quantities of the metals from the three soi
l/spoil materials, with DTPA generally extracting the least amount of
the metal (the trend was Mehlich 3 > 0.1N HCl > Mehlich 1 > DTPA). How
ever, DTPA removed larger quantities of metals from Tennessee spoil co
mpared to Alabama spoil and topsoil, suggesting the higher effectivene
ss of DTPA under acidic conditions. Metal concentrations in plant tiss
ue did not show a definite trend in correlation with metals extracted
by the four chemical extractants.