Availability to Lettuce of Arsenic and Lead from Trace Element Fertilizers in Soil

Abstract

Some waste-derived trace element fertilizers may contain elevated amounts of arsenic (As) and/or lead (Pb), and the impact of their use on As and Pb accumulation in soil and uptake by plants should be investigated. This greenhouse study examined how increasing rates of an iron (IR) fertilizer, containing 4806 mg kg −1 of As, and a zinc fertilizer (G-Zn), containing 18080 mg kg −1 of Pb, and liming affected As and Pb availability and uptake by lettuce (Lactuca sativa L.) in a silt loam soil. Additions of As as As 2 O 3 and Pb as PbCl 2 to the soil were included for comparison. Soil total and NaHCO 3 -extractable As increased with increasing inputs of As regardless of As source. This was true also for soil total and DTPA-extractable Pb. Sufficient oxidation of arsenopyrite (FeAsS) in the IR could have occurred, resulting in 36.4% of total As in IR being extractable by NaHCO 3 . Only extremely small fractions of the added As from IR (5 × 10 −3 %) and of the added Pb from G-Zn (7 × 10 −3 %) were accumulated in the plant. Source had an effect on As, but not Pb, accumulation by lettuce. The lower accumulation of As by the plant from IR than from As 2 O 3 could be attributed to a high molar ratio of Fe to As (419) in the readily labile As fraction to render As in IR less available than As in As 2 O 3 . The molar ratio of Fe to Pb in the readily labile fraction of Pb in G-Zn was zero, which limited the influence of Fe on the accumulation of Pb from G-Zn despite its extremely high total Fe (18.3%) content. The transfer coefficients of the added As (0.013) and Pb (0.014) over all sources and lime rates were very low. Since nearly all of As and Pb added from the fertilizers remained in the soil, effects of long-term use of the products on As and Pb accumulation in the soil and uptake by the plant remain to be studied.

The Rengen Grassland Experiment: soil contamination by trace elements after 65 years of Ca, N, P and K fertiliser application

“…In the 0-10 cm layer, an obvious effect of pH on the concentration of plant-available Zn was detected while no effect of liming was observed with Pb. These results were in accordance with other authors (Chowdhury et al 1997;Huang et al 2005;Száková et al 2007).…”

“…In the RGE, the effect of As present in basic slag combined with the enhanced mobility of As caused by the addition of phosphate fertilisers was apparent. Huang et al (2005) reported no significant changes in As mobility in limed soil, whereas in experiments published by Száková et al (2007) the mobile portion of As in limed soil tended to increase as in the RGE. There are many contradicting results that make it difficult to give exact explanations for these differences.…”

Factors influencing uptake of contaminated particulate matter in leafy vegetables

“…A low uptake of soil lead by the aboveground biomass of tested vegetables was apparent but a significantly increased Pb content in lettuce leaves at Chernozem and chard leaves at Fluvisol was observed (Table 5 and 6). A lower mobility and/or plantavailability of lead compared to other elements such as Cd and Zn was confirmed in this experiment as well as by Huang et al [35] and Sawidis et al [36]. The lead content in lettuce was variable by location and affected by individual soil physicochemical conditions, especially pH levels and clay content in the soils [12].…”

A Preliminary Study on Genetic Variation of Arsenic Concentration in 32 Different Genotypes of Leafy Vegetable

“…Therefore, these leafy vegetable cultivars can be considered as a As excluder (Baker and Whiting, 2002), comprising avoidance of metal uptake and restriction of metal transport to the shoots. This is consistent with the results reported by Huang et al (2005) using lettuce and when compared with other plants such as Pteris vittata (Francesconi et al,2002), the As concentrations were high in the shoot (aboveground) than in root, also the TFs were greater than 1.0. Wei et al (2005) found that the exclusion of metals from shoot has been regarded as a metal tolerant strategy.…”