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

Abstract

The potential for lead (Pb) and arsenic (As) transfer into vegetables was studied on old orchard land contaminated by lead arsenate pesticides. Root (carrot), leafy (lettuce), and vegetable fruits (green bean, tomato) were grown on seven “miniplots” with soil concentrations ranging from near background to ≈ 800 and ≈ 200 mg kg−1 of total Pb and As, respectively. Each miniplot was divided into sub-plots and amended with 0% (control), 5% and 10% (by weight) compost and cropped for 3 years. Edible portions of each vegetable were analyzed for total Pb and As to test the effect of organic matter on transfer of these toxic elements into the crop. Vegetable Pb and As concentrations were strongly correlated to soil total Pb and As, respectively, but not to soil organic matter content or compost addition level. For Pb vegetable concentrations, carrot ≥ lettuce > bean > tomato. For As, lettuce > carrot > bean > tomato. A complementary single-year study of lettuce, arugula, spinach, and collards revealed a beneficial effect of compost in reducing both Pb and As concentrations in leafy vegetables. Comparisons of all measured vegetable concentrations to international health-based standards indicate that tomatoes can be grown without exceeding standards even in substantially Pb- and As-contaminated soils, but carrots and leafy greens may exceed standards when grown in soils with more than 100–200 mg kg−1 Pb. Leafy greens may also exceed health-based standards in gardens where soil As is elevated, with arugula having a particularly strong tendency to accumulate As.

Trace Metal(oid) Accumulation in Edible Crops and Poplar Cuttings Grown on Dredged Sediment Enriched Soil

“…Arsenic has been reported to accumulate in the edible parts of different plant species (Li et al, 2016). McBride et al (2015) also found a significant accumulation of As in carrot, lettuce, green bean ( Phaseolus vulgaris L.), and tomato; however, the tested concentrations were much higher than those measured in our studied substrates. Rosas‐Castor et al (2014) observed As accumulation in maize ( Zea mays L.) when grown on a soil with an As concentration comparable with that in our substrates, but their recorded values in the shoot were mainly below our LQ for As (1.24 mg kg −1 , Supplemental Table S1).…”

Sources of Soil Pollution by Heavy Metals and Their Accumulation in Vegetables: a Review

“…The addition of phosphate increases soil permeability, thus contributing to arsenic migration deeper into the soil profile and entering groundwaters. This involves increasing its availability and uptake by plants (Scheckel et al 2013;McBride et al 2014;McBride et al 2015;Lim and McBride 2015).…”

Understanding arsenic dynamics in agronomic systems to predict and prevent uptake by crop plants

“…Demethylation and methylation occurred because both inorganic arsenic species and DMA were also detected in the percolating water 70 . As with mining-impacted soils, plants grown on soils that are high in arsenic from arsenical pesticide contamination take up higher levels of arsenic into their edible tissues, observed for example in potatoes 71 , carrots 72 and leafy green vegetables 73, 74 .…”