Chemical stabilization of cadmium in acidic soil using alkaline agronomic and industrial by-products.
In situ immobilization of heavy metals using reactive or stabilizing materials is a promising solution for soil remediation. Therefore, four agronomic and industrial by-products [wood biochar (WB), crushed oyster shell (OS), blast furnace slag (BFS), and fluidized-bed crystallized calcium (FBCC)] and CaCO3 were added to acidic soil (Cd = 8.71 mg kg(-1)) at the rates of 1%, 2%, and 4% and incubated for 90 d. Chinese cabbage (Brassica chinensis L.) was then planted in the soil to test the Cd uptake. The elevation in soil pH caused by adding the by-products produced a negative charge on the soil surface, which enhanced Cd adsorption. Consequently, the diethylenetriamine pentaacetic acid (DTPA)-extractable Cd content decreased significantly (P < 0.05) in the incubated soil. These results from the sequential extraction procedure indicated that Cd converted from the exchangeable fraction to the carbonate or Fe-Mn oxide fraction. The long-term effectiveness of Cd immobilization caused by applying the 4 by-products was much greater than that caused by applying CaCO3. Plant shoot biomass clearly increased because of the by-product soil amendment. Cd concentration in the shoots was < 10.0 mg kg(-1) following by-product application, as compared to 24 mg kg(-1) for plants growing in unamended soil.
Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, Pingtung, Taiwan.
Yao-Tsung
YT
Chang
Hsing-Cheng
HC
Hsi
Zeng-Yei
ZY
Hseu
Shao-Liang
SL
Jheng
D000327:Adsorption; D000383:Agriculture; D000818:Animals; D001673:Biodegradation, Environmental; D001937:Brassica / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007220:Industrial Waste / Q000032:analysis; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000378:metabolism*; D013624:Taiwan
D007220:Industrial Waste; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium