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Solubility and Plant Uptake of Cadmium in Soils Amended with Cadmium and Sewage Sludge
Author(s) -
Street Jimmy J.,
Lindsay W. L.,
Sabey B. R.
Publication year - 1977
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1977.00472425000600010016x
Subject(s) - cadmium , chemistry , soil water , sewage sludge , freundlich equation , environmental chemistry , adsorption , cation exchange capacity , solubility , sewage , environmental engineering , soil science , environmental science , organic chemistry
Adsorption and precipitation of Cd 2+ in soil suspensions were investigated as possible factors controlling Cd 2+ levels in soils. Both adsorption of Cd 2+ onto soils surfaces and possibly precipitation of cadmium minerals were evident in this study. At low cadmium levels solubility relationships in soils are best described by adsorption and fit the empirical Freundlich adsorption isotherm. Based on current thermodynamic data the solid phases CdCO 3 (log K sp = −12.07) and Cd 3 (PO 4 ) 2 (log K sp = −32.61) most likely limit Cd 2+ activities in soils. Under alkaline conditions, Cd 2+ activity decreased approximately 100‐fold for each unit increase in pH. In this study, CdCO 3 precipitated in sandy soils, having low cation exchange capacity (CEC), low organic matter, and pH values >7.0. DTPA‐extractable cadmium levels in soils were highly correlated ( r = 0.96) with Cd concentrations in corn ( Zea mays L.) seedlings grown on soils amended with Cd solutions, sewage sludge, or Cd‐spiked sewage sludge. Increasing Cd additions to the soil increased plant Cd regardless of the form of Cd added. Addition of inorganic Cd to the soil increased the Cd concentration of corn seedlings more than equivalent Cd additions in the form of sewage sludge or Cd‐spiked sludge.