Distribution of Chromium and Nickel in Plants and Soil from Serpentine and Other Sites

Abstract

Serpentine soils in various countries contain high levels of total chromium and nickel, and these are considered by some authors to be at least partly responsible for the characteristic infertility of the soil and paucity of vegetation (Robinson, Edgington & Byers 1935; Figiwara & Kikuchi 1950; Lounamaa 1956; Soane & Saunder 1959; Fernandez, Taboadela & Ojea 1965; Paribok & Alexeyeva-Popova 1966; Menezes de Sequeira 1968). Evidence which supports this conclusion can be of three types. First, foliar symptoms in crop plants such as oats grown in pot or field trials have been used to demonstrate toxicity, especially of nickel (Hunter & Vergnano 1953; Soane & Saunder 1959; Anderson, Meyer & Mayer 1973). Secondly, studies of the availability of chromium and nickel in the soil have been reported using a range of extractants, such as dilute acetic acid or ammonium acetate (Robinson et al. 1935; Soane & Saunder 1959; Spence & Millar 1963; Menezes de Sequeira 1968; Anderson et al. 1973). Generally it has been found that the level of available chromium is very low, often below the detection limit, whereas that of available nickel is much higher. Thirdly, there are reports of very high total contents of these elements in the indigenous plants (Lyon et al. 1968; Wild 1970; Lyon et al. 1971; Ritter-Studnicka & Dursun-Grom 1973; Brooks, Lee & Jaffre 1974; Wild 1974a,b). In view of the low level of availakble chromium and high level of available nickel, it would be expected that plants should contain higher concentrations of nickel than of chromium; in many species this is true, but exceptions can be found. Certainly marked differences between species in the mean element concentrations are found at particular sites (Lyon et al. 1968, 1971; Wild 1974b). In this paper we present data on the concentrations of available and total chromium and nickel in certain serpentine soils in Scotland and Austria, together with data on the concentrations of these elements in a range of indigenous species. We have already reported on the calcium and magnesium concentrations in the same soils and plants (Shewry & Peterson -1975). In this paper we also present the results of extracting chromium and nickel from the soils with a range of solutions and the results of studies on the binding and interconversion of 51Cr3+ and 5 -CrO4'in both serpentine and nonserpentine soils. Inter-element correlations within the soil and within plant species are also discussed. Extensive accounts of the vegetation on the serpentine soils in the Scottish areas concerned have been given by Spence (1957, 1959, 1970) and Proctor & Woodell (1971), while relevant experimental studies have been reported by Proctor (1971a,b).