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SQUID Magnetic Measurements on#1 -z+1,x-1/2,-y+1/2 Positional parameters and B(eq) for 2.62(5)2.40(5) 2.1(4) 2.4(4) 2.4(4) 2.3(4) 2.0(4) 2.0(4) 2.1(5) 2.7(6) 2.5(5) 3.2(6) 3.0(6) 3.9(7) 3.1(6) 4.3(7) 2.5(5) 3.7(6) 2.8(6) 3.1(6) 3.8(6) 3.3(6) 2.2(5) 2.2(5) 3.0(6) 2.6(5) 2.9(6) 3.5(6) 3.1(6) 3.7(7) 2.8(6) 3.3(6) 3.0(6) 2.5(5) 2.8(6) 3.0(6) 2.4(5) 2.6(5) 2.9(6) 2.5(5) 3.8(7) 3.3(6) 4.0(7) 3.7(7) 3.2(6) 3.2(6) 2.4(5) 2.9(6) 2.6(5) 0 1996 American Chemical Society J. Am. Chem. Soc. VI 18 Page8623 Laplaza Supplemental Page 9Positional parameters and B(eq) for 0.044(7) 0.038 (7 1.960 (7) 1.964 (7) 1.977 (7) 1.970 (7) 1.968 (7) 1.956 (7) 1.42 (1) 1.50(1)1.42 (1) 1.48 (1) 1.44 (1) 1.49 ( 122.8(9)122 (1) 117 ( 120 (1) 120 (1) 120 (

Cd is a potentially toxic metal that can accumulate in the human body with a half-life exceeding 10 years. There is evidence that low-leve1 exposure to Cd, derived from the diet, is associated with renal dysfunction (Buchet et al., 1990). Cd exposure has also been linked with pulmonary emphysema (Ryan et al., 1982) and possibly bone demineralization (Bhattacharyya et al., 1988). Pollution of the biosphere with this toxic metal has accelerated dramatically since the beginning of the industrial revolution (Nriago, 19791, and Cd accumulation in soil and water now poses a major environmental and human health problem, which is in need of an effective and affordable solution. The use of metal-accumulating plants to remove toxic metals, including Cd, from soil and aqueous streams has been proposed as a possible solution to this problem (reviewed by . This process of using plants for environmental restoration is termed "phytoremediation." Cd is a particularly favorable target metal for this new technology because it is readily transported and accumulated in the shoots of severa1 plant species (Wagner, 1994 The primary point of entry for Cd into plants is through the roots; however, for its efficient remova1 from the soil it must first be translocated to the harvestable parts of the shoot. To understand this translocation process, we undertook a study of Cd transport and accumulation in E. juncea, a high biomass crop plant within the Brassicaceae family, which has been identified as a potentially useful plant for phytoremediation (Banuelos and Meek, 1990). For comparison we have investigated a low biomass wild species within the same family, Thlaspi caerulescens, known to accumulate high levels of Cd in its shoots under certain conditions (Baker et al., 1994; Brown et al., 1994Brown et al., , 1995. MATERIALS AND METHODS Plant MaterialSeeds of Indian mustard (Brassica juncea L., cv 4263081, identified as a metal accumulator , and 24-28°C). The solutions were continuously aerated with an aquarium air pump and changed every 3 d. On the day of treatment, Cd was added to the hydroponic medium as CdSO, and the solutions were changed daily thereafter. Cd Accumulation in PlantsTotal shoot and root accumulation of Cd, Mn, and Cu in B. juncea and T. caerulescens were determined after 7 d of exposure to Cd, using a direct current plasma spectrometer (model SS-7, Fisons, Beverly, MA). Roots and shoots were harvested, washed in deionized water for 2 min, air dried at 60°C for 2 d, and then ground into a fine powder using a pestle and mortar.