Nanotechnology has been widely applied in agriculture, and understanding of the mechanisms of plant interaction with nanoparticles (NPs) as environmental contaminants is important. The aim of this study was to determine the effects of foliar application of cobalt oxide (Co3O4) NPs on some morpho-physiological and biochemical changes of canola (Brassica napus L.) leaves. Seeds were sown in plastic pots and grown under controlled conditions. Fourteen-day-old seedlings were sprayed with different concentrations of Co3O4 NPs (0, 50, 100, 250, 500, 1000, 2000, and 4000 mg L-1) at weekly intervals for 5 weeks. Growth parameters of the shoot (length, fresh and dry weights) were stimulated by low concentrations of Co3O4 NPs (50 and 100 mg L-1) and repressed by higher concentrations. Similar trends were observed in photosynthetic pigment contents. The results indicated that high concentrations of Co3O4 NPs increased lipoxygenase (LOX) activity and the malondialdehyde (MDA), hydrogen peroxide (H2O2), and dehydroascorbate (DHA) contents, but reduced the membrane stability index (MSI), ascorbate (ASC), and glutathione (GSH). Despite the increase of antioxidant capacity (DPPH) and the accumulation of nonenzymatic antioxidants (total flavonoids and flavonols) and osmolytes (proline, glycine betaine (GB) and soluble sugars) at high concentrations of Co3O4 NPs, the growth and photosynthesis were reduced. The defence system activity did not seem to be sufficient to detoxify reactive oxygen species (ROS). Altogether, high concentrations of Co3O4 NPs showed a phytotoxic potential for canola as an oilseed crop.
The article presents results of an input-output data inventory and life cycle assessment (LCA) for individual wastewater treatment plants (IWWTPs), considering their whole life cycle, including the stage of construction, use and end-of-life. IWWTPs located in the area of a medium-sized town in Poland, were assessed from a systemic perspective. The research was conducted basing on actual data concerning performance of 304 individual wastewater treatment plants in Żory. Environmental assessment was conducted with ReCiPe and TRACI methods. Greenhouse gases (GHG) emission, eutrophication, fossil fuel and metal depletion were calculated. The LCA was conducted basing on ISO 14040 standard with SimaPro 8 software and Ecoinvent 3 database. The system boundary ranged from cradle to grave. It was shown that, at the construction stage, GHG emission depends on the amount of used cement, polyethylene, concrete, PVC and polypropylene. At the use stage, the GHG emission is determined by the sewage treatment technology and application of a bio-reactor in IWWTPs. At the construction stage, the fossil fuel depletion is determined by the amount of used polyethylene, PVC, cement, polypropylene and concrete; while the metal depletion is determined by the amount of used stainless steel, copper and cast iron. Data inventory and LCA of IWWTPs are presented for the ﬁrst time. Conclusions of the work may support decisions taken by local governments concerning wastewater management in their area and promote and support solutions of high ecological standards.