Uptake of Weathered DDT in Vascular Plants:  Potential for Phytoremediation

Abstract

Since the discovery of its insecticidal properties and its subsequent widespread use, DDT [2,2-bis(chlorophenyl)-1,1,1-trichloroethane] has accumulated in the environment, having a wide range of adverse effects on nontarget species. Due to their hydrophobicity, DDT and other persistent organic pollutants are difficult to remove from contaminated soils, and increasingly so through time as weathering occurs. Phytoremediation is an emerging plant-based technology that may be used to cost-effectively remove or neutralize contaminants in the environment. For some phytoremediation strategies, it must first be possible to translocate hydrophobic chemicals across the root and through the shoot via an aqueous transpiration stream. The objective of this study was to compare the ability of five plant varieties (zucchini, tall fescue, alfalfa, rye grass, and pumpkin) to mobilize and translocate DDT. Plants were grown in the greenhouse in soil contaminated with DDT and its metabolites, DDD and DDE (sigmaDDT refers to all of DDT, DDD, and DDE) at two concentrations (high approximately 3700 ng/g, and low approximately 150 ng/g). All trays were covered with laboratory Parafilm to limit volatilization. Cucurbita pepo species (pumpkin and zucchini) achieved the highest translocation and bioaccumulation factors, and also extracted the highest absolute amounts of sigmaDDT from both the high and low sigmaDDT soils. In the high sigmaDDT soil treatment, pumpkin accumulated 1519 ng of sigmaDDT in the roots and 57,536 ng of sigmaDDT in the shoots, and zucchini accumulated 2043 ng of sigmaDDT in the roots and 35,277 ng of sigmaDDT in the shoots. With the exception of alfalfa and pumpkin, principal component analysis detected no preferential translocation or transformation of sigmaDDT compounds within the plant. The success of the Cucurbita pepo species in this study to extract and translocate such hydrophobic molecules may be related to their high transpiration volume, large above-ground biomass, and composition of root exudates. This suggests potential for their application in phytoremediation.

Plant uptake and dissipation of PBDEs in the soils of electronic waste recycling sites

“…We may safely draw the conclusion from the observation of a gradient distribution of PBDEs within the plants and no appreciable foliar uptake of PBDEs that the accumulation of PBDEs occurs by root uptake followed by gradual transfer from roots to stems and then to the leaves. Similar observations were also reported for the uptake of PCB and DDT when plants were grown directly in contaminated soils (Lunney et al, 2004;Slund et al, 2007Slund et al, , 2008 PBDEs inside plants, defined as the ratio of the concentration in plant roots to stems to leaves, were further calculated (Table S6 in the Supplementary material). Taking pumpkin as an example, the ratios were 2.8: 1.4: 1 for the soil from site 1, 3.9: 1.5: 1 for site 2, and 4.8: 1.7: 1 for site 3.…”

“…Lvjinli), and maize (Zea mays L. cv. Nongda 108) were chosen as the test plants because they are commonly used in studies on plant uptake of organic contaminants (Lunney et al, 2004;White et al, 2005) and have been shown to take up and transport PBDEs from roots to shoots Huang et al, 2010). Seeds were purchased from the Chinese Academy of Agricultural Sciences, Beijing, China.…”

Toxicity and uptake of cyclic nitramine explosives in ryegrass Lolium perenne

“…Results show that RDX and HMX were translocated in the ryegrass from roots to shoots, whereas CL-20 accumulated primarily in the roots with only limited translocation to the shoots. Translocation factors (TF) have been used to characterize chemical uptake with soil water, passage through the plant roots, and subsequent translocation to the above-ground portion of the plant (Lunney et al, 2004;Tu and Ma, 2002). In the present study, the greatest TF values for RDX (4.5) and for HMX (4.3) were established in ryegrass exposed to 91 and 3.6 mg/kg SSL, respectively (Table 2).…”

DDT uptake by arbuscular mycorrhizal alfalfa and depletion in soil as influenced by soil application of a non-ionic surfactant

“…There is a wealth of information demonstrating that POPs such as DDT have low availability/mobility because of their sequestration or weathering in soil. Nonetheless, there have been some greenhouse and field-scale studies of weathered DDT or DDE uptake in a range of plants with accumulation concentrations at the mg kg À1 level (Lunney et al, 2004;White, 2002;White et al, 2006). Extensive information exists on the negative effects of DDT and its metabolites on the environment and on human health (Vieira et al, 2001;Binelli and Provini, 2003).…”