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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Research » Publications at this Location » Publication #106647
Title: ASSOCIATION OF CADMIUM IN DURUM WHEAT GRAIN WITH SOIL CHLORIDE AND CHELATE-EXTRACTABLE SOIL CADMIUM

Author
item Norvell, Wendell
item WU, JIAPING - CORNELL UNIVERSITY
item HOPKINS, DAVID - NORTH DAKOTA STATE UNIV
item Welch, Ross

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cadmium is a heavy metal that occurs naturally as a trace metal throughout the environment. Cadmium is also a potentially toxic metal with no benefit to consumers, and its concentration in foods is subject to regulation by national and international agencies. Uptake of Cd by food crops needs to be understood in order to ensure a safe food supply and to meet applicable standards. We studied the composition of durum wheat grain and soil from a field in North Dakota, a part of the northern Great Plains in which soils are relatively rich in trace elements. Paired samples of soil and durum wheat grain were collected and analyzed. Cadmium in grain was related to the soil salinity, including the concentrations of chloride, sulfate, and sodium. Zinc, on the other hand, was related primarily to soil pH. The levels of cadmium in grain were most closely associated with soil chlorides. The greater uptake of cadmium in the presence of chlorides is presumably related to the formation of cadmium chloride complexes, which increase the solubility and mobility of cadmium.

Technical Abstract: Cadmium uptake by food crops needs to be understood because Cd is a potentially toxic heavy metal with no known benefit to consumers. Plant foods are the predominant sources of Cd in human diets. In this study, 124 paired samples of soil and grain were collected from a field of durum wheat (Triticum turgidum L. var. durum) cultivar "Munich" in northeastern North Dakota. This field was selected because it provided a range in pH and salinity. Cadmium in grain ranged widely from 0.025 to 0.359 mg kg-1, while Zn in grain was less variable ranging from 15 to 55 mg kg-1. Accumulation of Cd in grain was strongly and positively associated with chelate-extractable Cd in soil and with soil salinity as represented by soluble chloride, soluble sulfate, or extractable Na. Relationships to salinity were curvilinear. Unlike Cd in grain, Zn was most highly associated with soil pH, and relationships to salinity were always negative. The relationship of Cd in grain to the logarithm of water-extractable soil Cl (Clw) was especially close. A predictive model based on chelate-extractable Cd and log(Clw) in soil accounted for 67% of the variability of Cd in grain. Based on these results, and published work for other crops, we believe that the uptake and transport of Cd into durum wheat grain is stimulated by soil Cl. Although the mechanism for this stimulation is not clear, it is likely to involve increased solubility or availability of soil Cd resulting from the formation of chloro-complexes.