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Title: CHEMICAL ASSOCIATION OF TRACE ELEMENTS IN SOILS AMENDED WITH BIOSOLIDS: COMPARISON OF TWO BIOSOLIDS

Author
item SAJWAN, K - SAVANNAH STATE UNIV
item PARAMASIVAM, S - SAVANNAH STATE UNIV
item ALVA, ASHOK
item AFOLABI, J - SAVANNAH STATE UNIV

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 1/1/2005
Publication Date: 5/1/2005
Citation: Sajwan, K.S., Paramasivam, S., Alva, A.K., Afolabi, J. 2005. Chemical association of trace elements in soils amended with biosolids: Comparison of two biosolids, p. 151-162. In M.N.V. Prasad, K.S. Sajwan, and R. Naidu, (eds). Trace Elements in the Environment, Francis and Taylor Pubishers, Boca Raton, FL.

Interpretive Summary:

Technical Abstract: Understanding the chemical association of trace elements in soils amended with biosolids is very important because it determines their availability within and mobility beyond the rhizosphere. A sequential extraction method was used to determine the various chemical associations (exchangeable, sorbed, organic, carbonates, and sulfides) of Mn, Zn, Cu, Cd, Cr, Pb, and Ni at the end of sorghum-Sudan grass growth (65 days) in Candler fine sand (pH = 6.8) and in Ogeechee loamy sand (pH = 5.2) amended with sewage sludge (SS), which was obtained from two different sources at application rates of 0, 24.7, 49.4, 98.8, and 148.2 Mg/ha. Results of this study indicated that, irrespective of the soil type, Zn, Cd, Cr, Ni, Pb, and Mn in the labile fractions (exchangeable + sorbed) were almost nondetectable. Therefore, their availability to plants and mobility beyond the rhizosphere would be substantially low unless further transformations occurred from other fractions. Results also indicated that the presence of substantial amounts of trace elements studied were in the sulfide (HNO3) and organic (NaOH) fractions, irrespective of soil type. The exceptions were Pb, which was mainly present as carbonate (Na2EDTA) fraction, and the remaining Pb equally as sulfide (HNO3) and organic (NaOH) fractions. Furthermore, results indicated that the Cd was mainly present as carbonate (Na2EDTA) fraction. Irrespective of soil type, source, and rate of SS application, summation of quantities of various fractions of all the trace elements studied through sequential extraction procedure were 1 to 7% lower than those of total quantities of these trace elements extracted with 4 M HNO3 on fresh soil samples. They were also 5 to 20% lower than that of total trace elements determined on acid digestion described by the USEPA method. It was further evident that the application of SS shifted the solid phases containing the trace elements in soils away from those extractable with more severe reagents, such as 4 M HNO3, to those extractable with milder reagents, such as dilute NaOH and Na2EDTA.