Bioavailability of cadmium in municipal sewage sludge

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" Bioavailability of cadmium in municipal sewage sludge "
J. Jing T. J. Logan

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112744
Doc. No	:	TLpq303896413
Main Entry	:	J. Jing
	:	T. J. Logan
Title & Author	:	Bioavailability of cadmium in municipal sewage sludge\ J. JingT. J. Logan
College	:	The Ohio State University
Date	:	1990
student score	:	1990
Degree	:	Ph.D.
Page No	:	317
Abstract	:	Seventeen sludges were selected based on their Cd and P content. These sewage sludges were obtained directly from waste water treatment plants with total Cd contents ranging from 0.07 to 2.02 mmol/kg and were extracted by three methods using a sludge-to-solution ratio of 1:5. The extractants employed were: 0.05 M Ca(NO3)2, 0.05 M Ca(NO3)2 containing 5 usd\timesusd 10 M Na-EDTA, and 1 g Chelex 100 resin. Cd was speciated using the computer program, GEOCHEM, after measuring the major cations and ligands in the extraction solutions. Extractable Cd and Cd species were compared with Cd uptake by sudax, a sorghum x sudan hybrid (Sorghum bicolar, L. (Moench)), which was started in pots of acid-washed quartz sand. After the roots completely penetrated the sand, the pots were placed on soil/sludge mixtures containing 1.25 and 2.5 mg Cd. Uniform plant growth was maintained with a neutral nutrient solution specifically developed for grass growing in sand. Plant tops were harvested 6 weeks after transplanting and analyzed for total Cd. Paired comparisons across all three extraction methods gave a uniformly high correlation (R2 usd\congusd 0.97). Cd concentration in plants increased with Cd rate but the slopes were different for different sludges. Cd uptake was positively correlated with total sludge Cd concentration (R2 = 0.46), and with Cd extracted with Ca(NO3)2 (R2 = 0.91), with Ca(NO3)2 containing EDTA (R2 = 0.94), and with resin (R2 = 0.92) extraction. No single Cd species gave as high a correlation to plant uptake as the total Cd concentration in that extraction solution. A correlation between Cd uptake and Cd/P showed that, as the sludge P content increased, the bioavailability of Cd decreased. Resin extraction, which gives a strong positive correlation, is recommended as a highly reliable and convenient method for estimation of Cd bioavailability for routine analyses.
Subject	:	Agricultural chemicals
	:	Earth sciences
	:	Environmental science
	:	Geochemistry
	:	Health and environmental sciences
	:	Pure sciences