689 Phosphate and micronutrient fertilizers contain potentially harmful trace elements, such as arsenic (As), cadmium (Cd), and lead (Pb). We investigated if application of these fertilizer increases the As, Cd, and Pb concentrations of the receiving soils. More than 1000 soil samples were collected in seven major vegetable production regions across California. Benchmark soils (no or low fertilizer input) sampled in 1967 and re-sampled in 2001 served as a baseline. Soils were analyzed for total concentrations of As, Cd, Pb, P, and Zn. he P and Zn concentrations of the soils were indicators of P fertilizer and micronutrient inputs, respectively. Results showed that the concentrations of these elements in the vegetable production fields in some production areas of California had been shifted upward. Principal component analysis and cluster analysis showed that the seven production areas could be sorted into three categories: (i) enrichment of As, Cd, and Pb, which was associated with the enrichment of P and Zn in one of the seven areas surveyed; (ii) enrichment of As, which was associated with enrichment of Zn in two of the seven areas surveyed; and (iii) no remarkable correlation between enrichment of As, Cd, and Pb and enrichment of P and Zn in the other four areas surveyed. Arsenic, Cadmium, and Lead in California Cropland Soils: Role of Phosphate and Micronutrient Fertilizers Weiping Chen,* Natalie Krage, and Laosheng Wu University of California–Riverside Genxing Pan Nanjing Agricultural University Maryam Khosrivafard California Department of Agriculture Andrew C. Chang University of California–Riverside P hosphate f ertilizers and Fe–Mn–Zn micronutrient amendments are routinely applied on croplands to improve yields. However, the ingredients used for formulating the fertilizers and amendments may be contaminated with trace elements such as As, Cd, and Pb (McLaughlin et al., 1996; Raven and Loeppert, 1997; Bowhay, 1997). Based on a survey by the California Department of Food and Agriculture (CDFA, 1998), the trace element concentration of commercial P-fertilizers and micronutrient amendments marketed in California may vary from essentially nil to as high as 85 mg kg −1 for As, 5000 mg kg −1 for Cd, and 73,500 mg kg −1 for Pb. Although the amount being incorporated with a single application may be negligible compared with that present in the volume of receiving soil and may not be readily detectable by routine field sampling and measurement protocols, repeated applications can lead to a gradual buildup of the concentrations of trace elements in soils over time. Researchers have demonstrated that applications of P-fertilizer might inadvertently increase the trace element contents of the receiving cropland soils, especially Cd (Andrewes et al., 1996; McLaughlin et al., 1996; Richards et al., 1998; Moon et al., 2000; Abollino et al., 2002; Mann et al., 2002; de Meeữs et al., 2002). Vegetable production requires considerably higher levels of fertilizer inputs than other crops and therefore represents the worse case scenario in the accumulation of fertilizer-borne trace elements. For example, the vegetables grown in the Imperial Valley (California) typically receive 563 kg ha −1 of ammoniated phosphate (11–52–0) pre-planting (Meister et al., 2004). he climate in California often permits year-round production, and multiple crops are harvested annually. Croplands dedicated for vegetable production in California are more heavily fertilized and therefore are more likely to accumulate trace elements. he enrichments in the soils may lead to inadvertent and ac- celerated transfer of trace elements through the food chain. It has been reported that the concentration of an element in plant tissue increases in proportion to its concentration in soils (He and Singh, 1994; Guttormsen et al., 1995; Grant and Bailey, 1998; Huang et Abbreviations: CLS, Colusa County; COA, Coachella Valley; EF, enrichment factor; IMP, Imperial Valley; OXV, Oxnard/Ventura Area; PCA, principal components analysis; SLN, Salinas Valley; STM, Santa Maria Valley. W. Chen, N. Krage, L. Wu, and A.C. Chang, Dep. of Environmental Sciences, Univ. of California Riverside, CA. G. Pan, Inst. of Resource, Ecosystem and Environment, Nanjing Agricultural Univ., China. M. Khosrivafard, California Dep. of Agriculture, Sacramento, CA. Copyright © 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including pho- tocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Published in J. Environ. Qual. 37:689–695 (2008). doi:10.2134/jeq2007.0444 Received 21 Aug. 2007. *Corresponding author (chenweip@yahoo.com.cn). © ASA, CSSA, SSSA 677 S. Segoe Rd., Madison, WI 53711 USA TECHNICAL REPORTS: HEAVY METALS IN THE ENVIRONMENT