A Cu(OH)2nanopesticide induced oxidative stress and activated the antioxidant defense system in cucumber plants.

Copper-based nanopesticides are increasingly being used in the agriculture, especially in organic farming. This has triggered some concerns about their risk to environmental and human health. In this study, 24-day-old lettuce plants grown in soil were exposed via the leaves to different concentrations (0, 1050 and 1555 mg/L) of Cu(OH) 2 nanopesticides for one month. Results showed Cu was mainly localized in lettuce leaves (823-1111 and 1353-2008 mg/kg in vascular and photosynthetic tissues), which may potentially increase Cu intake and impact human health. In addition, foliar application of Cu(OH)2 nanopesticide significantly increased potassium concentration in lettuce leaves by 6-7% and 21-28%, in vascular and photosynthetic tissues. A Gas Chromatography-Time-of-Flight Mass Spectrometry (GC-TOF-MS) based metabolomics approach was applied to determine hundreds of organic compounds simultaneously. Using relative quantitation and Partial Least Squares-Discriminant Analysis (PLS-DA) clustering of all compounds, clear differences were observed in the metabolite profiles of control and Cu(OH) 2 nanopesticides treated leaves. Discriminating compounds include amino acids, organic acids, polyamines, vitamin C and polyphenols. Dehydroascorbic acid and cis-caffeic acid, which are important antioxidants, were significantly decreased (19-33% and 5-8%) due to foliar exposure to the nanopesticide. Total antioxidant capacity was significantly decreased 20-23% after exposure to Cu(OH) 2 nanopesticides. There was also up-and down-regulation of a number of amino acids, particularly 4-hydroxybutytic acid (GABA) which decreased 50% compared to the control, potentially affecting the overall nutritional value of lettuce leaves exposed to the Cu(OH) 2 nanopesticides. In future work, determining an appropriate level of nanopesticide will be important to obtain the antifungal benefits without resulting in a significant decrease in nutritional value.

• Fast magnetic nanosorbents for simultaneous removal of PAHs and metals • Stable remediation performance across wide pH range (4-9) • High water hardness resistance across wide range of Ca 2 + or Mg 2 + concentration • Low energy use for regeneration of adsorbent and able to reuse multiple times Many industrial wastewaters are contaminated with both heavy metal ions and organic compounds, posing a major threat to public health and the environment. In this study, magnetic nanoparticle adsorbents, namely Mag-PCMA-T, which contain a maghemite core and a silica mesoporous layer that permanently confines surfactant micelles within the mesopores, were synthesized to achieve simultaneous removal of polycyclic aromatic hydrocarbons (PAHs) (1 mg/L) and metal contaminants (1 mg/L). The individual removal efficiency of Cd 2+ and acenaphthene using Mag-PCMA-T was evaluated under a range of initial ion concentrations and adsorbent dosages, as well as the competitive adsorption with Cd 2+ and acenaphthene simultaneously present. The isotherms and kinetics of Cd 2+ and acenaphthene sorption onto Mag-PCMA-T were determined. Mag-PCMA-T removed N85% of the acenaphthene in b30 min, with relatively high sorption capacity (up to 1060 mg/kg). Mag-PCMA-T also exhibited high sorption capacity for Cd 2+ (up to 2250 mg/kg). The simultaneous sorption performance was stable across a wide pH range (4-9) as well as in the presence of competitive metal ions (Ca 2+ and Mg 2+ ) or natural organic matters. The Mag-PCMA-T can be regenerated and reused, providing a sustainable, fast, convenient, and efficient approach for water treatment. b s t r a c t a r t i c l e i n f o© 2016 Published by Elsevier B.V. Contents lists available at ScienceDirectScience of the Total Environment