[Effects of phosphorus application on translocation of lead, zinc and cadmium in the soil-plant system].
A pot experiment was conducted to determine the influence of phosphorus (P) application on the translocation and accumulation of lead (Pb), zinc (Zn), and cadmium (Cd) in a soil solid-liquid-plant system using a plant Swamp Morningglory (Ipomoea aquatica Forak) as an indicator and Visual MINTEQ model. A contaminated soil containing 22,830 mg x kg(-1) Pb, 746 mg x kg(-1) Zn, and 10 mg x kg(-1) Cd was in the root was significantly decreased after P application, while the Zn concentration were increased, but no impact on Cd concentration after P application, compared to the control. Further more, concentrations of Pb, Zn, and Cd in plant tissue were sharply reduced after P application by 53%-92%, 35%-71%, and 59%-86%, respectively; Concentrations decreased exponentially with increasing amount of P; Relationship between Pb and Zn (r = 0.993, p < 0.01), between Pb and Cd (r = 0.986, p < 0.01) suggested that there was a positive relationship between the mechanisms controlling the phytoavailability of Pb, Zn, and Cd. It was suggested that Cd concentrations in the soil solution were reduced generally by P application as a result of the increased soil pH, and Zn concentrations were no change, but Pb concentrations were increased. Species distribution showed that PbHPO4, PbOH+ and PbH2PO4+ were the main complexation species of Pb in the soil equilibrium solution after P application. It was also suggested that Pb accumulation by root were negatively correlated to Pb in soil solution with coefficient of -0.872 (p < 0.05), and that water soluble Zn and Cd concentrations were reduced while the concentrations in root tissues were increased after P addition. These results indicate the difference between Zn, Cd and Pb and suggest that P as KH2PO4 successfully decreased the phytotoxicity of Pb, Zn, and Cd in the contaminated soil.
Wang
Bi-Ling
BL
College of Environmental Science and Natural Resources, Zhejiang University, Hangzhou 310029, China. w-biling@sohu.com
Xie
Zheng-Miao
ZM
D002104:Cadmium / Q000737:chemistry* / Q000302:isolation & purification; D004784:Environmental Monitoring; D027741:Ipomoea / Q000187:drug effects; D007854:Lead / Q000737:chemistry* / Q000302:isolation & purification; D008906:Mining; D010710:Phosphates / Q000737:chemistry / Q000494:pharmacology*; D017680:Potassium Compounds / Q000737:chemistry / Q000494:pharmacology*; D012989:Soil Pollutants / Q000737:chemistry* / Q000302:isolation & purification; D015032:Zinc / Q000737:chemistry* / Q000302:isolation & purification
D010710:Phosphates; D017680:Potassium Compounds; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; C013216:potassium phosphate; D015032:Zinc