Evaluation of nanoremediation strategy in a Pb, Zn and Cd contaminated soil

Carmen Fajardo; Sebastián Sánchez-Fortún; Gonzalo Costa; Mar Nande; Pedro Botías; Jesús García-Cantalejo; Gerardo Mengs; Margarita Martín

doi:10.1016/j.scitotenv.2019.136041

Evaluation of nanoremediation strategy in a Pb, Zn and Cd contaminated soil

Sci Total Environ. 2020 Mar 1:706:136041. doi: 10.1016/j.scitotenv.2019.136041. Epub 2019 Dec 10.

Authors

Carmen Fajardo¹, Sebastián Sánchez-Fortún², Gonzalo Costa², Mar Nande², Pedro Botías³, Jesús García-Cantalejo³, Gerardo Mengs², Margarita Martín²

Affiliations

¹ Facultad de Farmacia, Universidad de Alcalá, 28805 Alcalá de Henares (Madrid), Spain.
² Facultad de Veterinaria, Universidad Complutense, 28040 Madrid, Spain.
³ Unidad de Genómica, Universidad Complutense de Madrid, 28040 Madrid, Spain.

PMID: 31855644
DOI: 10.1016/j.scitotenv.2019.136041

Abstract

We addressed the efficiency of a nanoremediation strategy using zero-valent iron nanoparticles (nZVI), in a case of co-mingled heavy metals (HM) pollution (Pb, Cd and Zn). We applied a combined set of physical-chemical, toxicological and molecular analyses to assess the effectiveness and ecosafety of nZVI (5% w/w) for environmental restoration. After 120 days, nZVI showed immobilization capacity for Pb (20%), it was scarcely effective for Zn (8%) and negligibly effective for Cd. The HMs immobilization in the nZVI treated soils (compared to control soil), reaches its maximum after 15 days (T3) as reflected in the decrease of HM toxicity towards V. fischeri. The overall abundance of the microbial community was similar in both sets of samples during all experiment, although an increase in the number of metabolically active bacteria was recorded 15 days post treatment. We studied the induced impact of nanoremediation on the soil microbial community structure by Next Generation Sequencing (NGS). Even when higher HM immobilization was recorded, no significant recovery of the microbial community structure was found in nZVI-treated soil. The most marked nZVI-induced structural shifts were observed at T3 (increase in the Firmicutes population with a decrease in Gram-negative bacteria). Predictive metagenomic analysis using PICRUSt showed differences among the predicted metagenomes of nZVI-treated and control soils. At T3 we found decrease in detoxification-related proteins or over-representation of germination-related proteins; after 120 days of nZVI exposure, higher abundance of proteins involved in regulation of cellular processes or sporulation-related proteins was detected. This study highlights the partial effectiveness of nanoremediation in multiple-metal contaminated soil in the short term. The apparent lack of recovery of biodiversity after application of nZVI and the decreased effectiveness of nanoremediation over time must be carefully considered to validate this technology when assurance of medium- to long-term immobilization of HMs is required.

Keywords: Availability; Ecotoxicogenomics; Heavy metal; Nanoremediation; Next Generation Sequencing; nZVI.