Fate of biosolids trace metals in a dryland wheat agroecosystem

Ippolito, J.A. and Barbarack, K.A. (2008) Fate of biosolids trace metals in a dryland wheat agroecosystem. Journal of Environmental Quality. 37:2135-2144.

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Abstract

Biosolids land application for beneficial reuse applies varying
amounts of trace metals to soils. Measuring plant-available or
total soil metals is typically performed to ensure environmental
protection, but these techniques do not quantify which
soil phases play important roles in terms of metal release or
attenuation. This study assessed the distribution of Cd, Cr,
Cu, Mo, Ni, Pb, and Zn associated with soluble/exchangeable,
specifically adsorbed/carbonate-bound, amorphous Mn
hydroxyoxide-bound, amorphous Fe hydroxyoxide–bound,
organically complexed, and residual inorganic phases. Biosolids
were applied every 2 yr from 1982 to 2002 (except in 1998)
at rates of 0, 6.7, 13.4, 26.8, and 40.3 dry Mg biosolids ha−1
to 3.6- by 17.1-m plots. In 2003, 0- to 20-cm and 20- to
60-cm soil depths were collected and subjected to 4 mol L−1
HNO3 digestion and sequential extraction. Trace metals were
concentrated in the 0- to 20-cm depth, with no significant
observable downward movement using 4 mol L−1 HNO3 or
sequential extraction. The sequential extraction showed nearly
all measurable Cd present in relatively mobile forms and Cr,
Cu, Mo, Ni, Pb, and Zn present in more resistant phases.
Biosolids application did not affect Cd or Cr fractionation
but did increase relatively immobile Cu, Mo, and Zn phases
and relatively mobile Cu, Ni, and Pb pools. The mobile
phases have not contributed to significant downward metal
movement. Long-term, repeated biosolids applications at rates
considered several times greater than agronomic levels should
not significantly contribute to downward metal transport and
ground water contamination for soils under similar climatic
conditions, agronomic practices, and histories.

Item Type:	Article
NWISRL Publication Number:	1275
Subjects:	Manure > Chemistry
Depositing User:	Users 6 not found.
Date Deposited:	18 Dec 2008 21:43
Last Modified:	18 Oct 2016 15:34
Item ID:	1298
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1298