SOIL SOLID PHASE CONTROLLING ZN ACTIVITY IN PORE WATER FROM SOIL PREVIOUSLY TREATED WITH SEWAGE SLUDGE | ||
| Journal of Soil Sciences and Agricultural Engineering | ||
| Article 8, Volume 26, Issue 11, November 2001, Pages 7395-7409 PDF (626.92 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jssae.2001.257003 | ||
| Author | ||
| S.H. Badawy | ||
| Soil Science Department, Faculty of Agriculture, Cairo University, Giza, Egypt. | ||
| Abstract | ||
| Ten soil samples were used to measure free Zn2+ in soil pore water obtained from soil treated previously with sewage sludge. The samples were chosen to cover soils having different enrichment rates of heavy metals to sewage sludge. The cation exchange resin method was used to measure free Zn2+ in soil pore water. Soil total Zn values ranged from 87 to 282 within an average 165 mgkg-1. DTPA, NH4NO3 extractable-Zn, and pore water soluble Zn represented approximately as average 12, 0.91, and 0.73 % from the total, respectively. Pore water Free Zn2+ represented approximately 0.17, 1.46, 26, and 37% from total, DTPA, NH4NO3 extractable-Zn, and soluble Zn, respectively. The Zn activities were very low, ranged from 10-6.5 to 10-8.01 M, and were inversely related to pH, with a correlation coefficient (R2 = 0.95; P < 0.01). The activity of Zn2+ in the soil could be predicted from the equation: Log (Zn2+) = 6.49 – 2pH The measured Zn2+ activities were compared to the solubility of various Zn minerals using a -log Zn2+ vs. pH solubility diagram. The diagram suggests that zinc ferrite (ZnFe2O4) in equilibrium with soil-Fe is a likely solid phase controlling (Zn2+) activities in these soils. | ||
| Keywords | ||
| Zinc activity; Zinc solubility; free Zinc; polluted soils; heavy metals; Soil pore water; Speciation | ||
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