Cadmium in soil and winter wheat grain in southern Sweden .1. Factors influencing Cd levels in soils and grain

The guideline level for Cd contents in cereals of 100 mu g kg(-1) proposed by the Coder Committee on Cereals, Pulses and Legumes has increased concern regarding Cd levels in Swedish winter wheat. In this study, Cd levels in soil and grain and factors influencing these variables were investigated in Skane, the southernmost province in Sweden. In 1992, soils and winter wheat grain were sampled at sites distributed randomly over Skane. Soil Cd contents were influenced only slightly by the pH, clay content and organic matter content of the soil, but were rather strongly correlated with soil contents of both Cu and Zn. Cadmium levels in grain were generally rather low owing to a prolonged summer drought. Still, in a few of the samples, mostly from sites with Cd-rich soils, Cd contents exceeded 100 mu g kg(-1) Also, at less extreme sites, grain Cd contents generally increased with the soil Cd content. The distribution of grain Cd contents was such that in a less dry year, also a portion of wheat grown on soils with a Cd content of only up to 50% above average may have Cd contents near or above 100 mu g kg(-1). A comparison with data from other investigations showed that Cd contents in both soil and grain were higher in Skane than in other parts of Sweden. However, the difference in grain Cd contents was larger than the difference in soil Cd contents, indicating that Cd in soils may be more available in Skane than in other parts of Sweden.