Arsenic and Lead Uptake by Vegetable Crops Grown on Historically Contaminated Orchard Soils

Abstract

Transfer of Pb and As into vegetables grown in orchard soils historically contaminated by Pb arsenate pesticides was measured in the greenhouse. Lettuce, carrots, green beans and tomatoes were grown on soils containing a range of total Pb (16.5–915 mg/kg) and As (6.9–211 mg/kg) concentrations. The vegetables were acid-digested and analyzed for total Pb and As using ICP-mass spectrometry. Vegetable contamination was dependent on soil total Pb and As content, pH, and vegetable species. Arsenic concentrations were highest in lettuce and green beans, lower in carrots, and much lower in tomato fruit. Transfer of Pb into lettuce and beans was generally lower than that of As, and Pb and As were strongly excluded from tomato fruit. Soil metal concentrations as high as 400 mg/kg Pb and 100 mg/kg As produced vegetables with concentrations of Pb and As below the limits of international health standards.

Arsenic and Lead Uptake by Vegetable Crops Grown on an Old Orchard Site Amended with Compost

“…Consistent with results from other studies (McBride et al 2012; 2014), the tissue Pb and Al concentrations were significantly correlated (r = 0.574, p<0.05), an indication that soil particle contamination of the foliage probably accounted for many of the elevated Pb levels measured in field-grown lettuce. The high clay and exchangeable base cation content, as well as the generally non-acid nature of the orchard soils from this site, maintain soluble and phytoavailable Pb at very low concentrations in this soil (McBride, 2013). Physical contamination (soil particle adherence) may therefore be the most important mechanism of Pb transfer to the leafy and root crops in particular.…”

“…Stilwell et al (2006) measured high concentrations of As in some crops (arugula and chives) but not others grown on soils contaminated by As from pressure-treated wood. Our results from greenhouse studies to date reveal substantial risk of exceeding international standards for vegetable crops when soil total As exceeds 100 mg kg −1 and Pb exceeds 400 mg kg −1 (McBride 2013). Nevertheless, there is still insufficient basic knowledge to make even approximate predictions of As or Pb content for a wide range of crops grown on soils with different properties.…”

“…Arsenic uptake from orchard soils is frequently high enough to cause phytotoxicity in sensitive crops (Bishop and Chisholm 1962; Ross and Crowe 1976). Our own studies of As and Pb uptake from orchard soils by leafy green crops showed that there is a wide range of potential for uptake depending on crop species and the part of the plant analyzed (McBride 2013; McBride et al 2012). Thus, root and leafy crops have a much higher potential for Pb and As contamination than most vegetable fruits.…”

Concentrations of lead, cadmium and barium in urban garden-grown vegetables: The impact of soil variables

“…Though available data are limited, when the number of environmental and soil variables is reduced, as is done with single-site field studies and greenhouse research with one particular soil containing a range of Pb concentrations, a clearer relationship between vegetable Pb and soil Pb emerges (McBride, 2013; and unpublished results).…”

Arsenic Distribution in Green Bean Yield Irrigated by Waste Water

“…Farooqi et al studied that amount of arsenic in soil surface samples was 10.2 mg/kg, with highest concentration 35 mg/kg [12]. McBride grew green beans, lettuce, carrot and tomatoes on soil containing a range of total as (6.9-211 mg/kg) concentrations [13]. He found that arsenic concentration highest in lettuce and green beans.…”