Plant-assisted rhizoremediation of decabromodiphenyl ether for e-waste recycling area soil of Taizhou, China

Abstract

To develop an effective phytoremediation approach to purify soils polluted by decabromodiphenyl ether (BDE-209) in e-waste recycling area, pot experiments were conducted through greenhouse growth of seven plant species in BDE-209-polluted soils. The hygrocolous rice (Oryza sativa L.) cultivars (XiuS and HuangHZ) and the xerophyte ryegrass (Lolium perenne L.) were found to be as the most effective functional plants for facilitating BDE-209 dissipation, with the removal of 52.9, 41.9, and 38.7% in field-contaminated soils (collected directly from field, with an average pollution concentration of 394.6 μg BDE-209 kg(-1) soil), as well as 21.7, 27.6, and 28.1% in freshly spiked soils (an average pollution concentration of 4413.57 μg BDE-209 kg(-1) soil, with additional BDE-209 added to field-contaminated soils), respectively. Changes in soil phospholipid fatty acid (PLFA) profiles revealed that different selective enrichments of functional microbial groups (e.g., arbuscular mycorrhizal fungi and gram-positive bacteria) were induced due to plant growth under contrasting water management (flooded-drained sequentially, flooded only, and drained only, respectively). The abundance of available electron donors and acceptors and the activities of soil oxido-reductases were also correspondingly modified, with the activity of catalase, and the content of NO3(-) and Fe(3+) increased generally toward most of the xerophyte treatments, while the activity of dehydrogenase and the content of dissolved organic carbon (DOC) and NH4(+) increased toward the hygrophyte treatments. This differentiated dissipation of BDE-209 in soils as function of plant species, pollution doses and time, and water-dependent redox condition. This study illustrates a possibility of phytoremediation for BDE-209-polluted soils by successive cultivation of rice followed by ryegrass coupling with suitable water management, possibly through dissipation pathway of microbial reductive debromination and subsequent aerobic oxidative cleavage of benzene ring.

Improved rhizoremediation for decabromodiphenyl ether (BDE-209) in E-waste contaminated soils

“…In typical E-waste dismantling area, polybrominated diphenyl ethers (PBDEs), used as flame retardants in electronic components, have drawn great public attention. Their environmental release during non-standard dismantling of E-waste has caused serious contamination in Taizhou and Guiyu of China, two of the largest E-waste dismantling sites in the world (He et al, 2015). Previous pollution surveys reported that the total concentration of PBDEs reached to greater than 3000 µg$kg -1 which caused serious environmental damage and food security risk (Qu et al, 2007;Zhao et al, 2010;Wang et al, 2011b).…”

“…Therefore, facilitating environmental removal of PBDEs from polluted soils is crucial for pollution control and remediation in these Ewaste dismantling areas (Deng et al, 2016). Of all the 209 kinds PBDE congeners, the highest brominated decabromodiphenyl ether (BDE-209) owns the highest amount in total production of PBDEs because of its lower price and superior performance (Sjödin et al, 1999;He et al, 2015). There is thus an urgent need to mitigate the heavy pollution of BDE-209.…”

“…Although they are highly efficient for remediation, these techniques are usually not the best for farmland soils, due to their high costs, secondary pollution and drawbacks for agricultural production. Therefore, green biotic remediation techniques such as bioremediation through the growth of plants are more and more favorable (Huang et al, 2013;He et al, 2015). Benefits of plant growth were verified in facilitating the dissipation of organic contaminants (OCs) in plant rhizosphere (e.g.…”

Influences of artificial root exudate components on the behaviors of BDE-28 and BDE-47 in soils: desorption, availability, and biodegradation

“…Biological activity, especially root exudation, has been demonstrated to significantly affect the behaviors of organic contaminants in soils (Luo et al 2006;Zhu et al 2009;Balseiro-Romero et al 2014;Martin et al 2014;He et al 2015). Some studies have evidenced the effects of root exudates on the desorption and availability of organic contaminants in soils.…”

Sustainable Options for Mitigation of Major Toxicants Originating from Electronic Waste

“…The plant species basically uptake, store or degrade the pollutants. Numerous plant species have been successfully applied for restoration of sites contaminated with diverse pollutants arising from e-waste 19 . Chen et al 20 have tested the efficiency of four plant species, Medicago sativa (alfalfa), Lolium perenne (rye grass), Festuca arundinacea (tall fescue), and Oryza sativa (rice) for phytoremediation of PCB-contaminated soil from an e-waste disposal site.…”