Wednesday, November 7, 2007
246-5

Lead and Arsenic Uptake by Carrots Grown on Five Orchard Soils with History of Lead-Arsenate Application.

Eton E. Codling1, Rufus Chaney2, and Carrie E. Green1. (1) USA-ARS, 10300 Baltimore Ave, Beltsville, MD 20705, (2) USDA-ARS, USDA-ARS-AMBL, Bldg. 007 Barc-west, Beltsville, MD 20705-2350

Lead arsenate was used to control codling moth in orchards. Consequently many orchard soils are contaminated with lead (Pb) and arsenic (As). Some of these lands are being used for vegetable crop production. Lead and As have become an important environmental concern, due to their potential carcinogenic and neurological properties. The objective of this study was to determined the uptake of As and Pb by carrots grown lead arsenate contaminated soils. Five orchard soils (Bagstown, Hudson Spike Burch and Chashmont) with total Pb concentrations ranging from 350 to 1159 mg kg-1 and As ranging from 43 to 290 mg kg-1 were planted with three carrot verities (Gold king, Monique and Denver-26). A soil with no lead arsenate application (Christiana) was used as control. Soils were mixed with lime and fertilizer to achieve a pH of 6.5. Four kilograms of each soil were placed into a 20 cm diameter plastic pot and planted with fifteen carrot seed. Pots were placed in a growth chamber in a randomized complete block design with 16 hours of light at 25oC and 8 hr dark at 19oC. All treatments were replicated four times. Plants were thinned to5 plants per pot and grown for 90 days. Carrots ware harvested, washed, peeled and freeze-dried. Arsenic and Pb concentrations were determined using a ICP-MS after microwave for digestion. The highest yield (25 g) was in the plants grown on the Bagstown soil. Lead and arsenic concentrations increased in plants grown on the orchard soils compared to the control. Arsenic concentrations were higher in the peel than the root, while Pb concentrations were highest in the roots. The elevated levels of As and Pb in these carrot could be a potential health concern. However, further study are needed to determine bioaccessibility of As and Pb in these carrots.