With increasing global population, innovations in agriculture will be essential for a sustainable food supply. We compare commercial CuO NP to synthesized Cu 3 (PO 4 ) 2 •3H 2 O nanosheets to determine the influence of coordinating anion, particle morphology, and dissolution profile on Fusarium oxysporum f. sp. niveum induced disease in watermelon. Copper dissolution in organic acid solutions that mimic complexing agents found in plants was increased by 2 orders of magnitude relative to water. Cu 3 (PO 4 ) 2 •3H 2 O nanosheets showed a rapid initial dissolution, with equilibration after 24 h; CuO NP exhibited continuous particle dissolution. In a greenhouse study, Cu 3 (PO 4 ) 2 •3H 2 O nanosheets at 10 mg/L significantly repressed fungal disease as measured by yield and by a 58% decrease in disease progress. Conversely, CuO NP only yielded significant effects on disease at 1000 mg/L. In field studies, similar enhanced disease suppression was noted for Cu 3 (PO 4 ) 2 •3H 2 O nanosheets, although biomass and yield effects were variable. The method of application was a significant factor in treatment success, with the dip method being more effective than foliar spray; this is likely due to homogeneity of coverage during treatment. The data show that Cu-based nanoscale materials can be an effective and sustainable strategy in the crop disease management but that particle characteristics such as morphology, coordination environment, and dissolution profile will be important determinants of success.

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Environmental context. Iron, a limiting nutrient of plankton in the ocean, is deposited to the sea from atmospheric aerosols. In particular, atmospheric acidic conditions promote dissolution of iron from fly ash, a byproduct of coal-fired power plants. Here, we report that the iron leached from fly ash depends on its source region, and that the type of combustion process may influence the iron species mobilized.Abstract. Fly ash, an iron-containing by-product of coal-fired power plants, has been observed in atmospheric aerosol plumes. Under the acidic atmospheric conditions resulting from the uptake of atmospheric gases, iron leached from fly ash can impact global biogeochemical cycles. However, the fly ash source region, as well as its generating power plant, plays an important role in the amount, speciation and lability of iron. Yet no comparative studies have been made on iron leached from fly ash from different sources. This study reports the iron mobilisation by proton-promoted dissolution from wellcharacterised fly ash samples from three distinctive locations: the USA Midwest, north-east India and Europe. In addition, pH dependency was also investigated. Proton-promoted dissolution showed a variability between source regions with a relative iron leach in the order USA Midwestern . north-east Indian . European ash. In addition, the initial rate of iron leach suggests that source region is indeed a determining factor in the iron leaching capacity of fly ash, because dissolution from Midwestern fly ash is also faster than both European and Indian ash. Finally, the combustion process of fly ash proved to be significant for the iron speciation, given that well-combusted fly ash samples leached mostly Fe 3þ rather than bioavailable Fe 2þ . The role of fly ash should therefore be taken into account in order to better understand the effects of combustion particles in atmospheric iron deposition.

Achieving and sustaining global food security will become increasingly difficult as a changing climate increases crop loss due to greater pest and pathogen activity. Nanoenabled agrichemical delivery platforms offer a unique potential to manage pathogens and increase productivity with reduced negative environmental consequences. Two greenhouse experiments were conducted to assess the potential of in-house synthesized Cu3(PO4)2·3H2O nanosheets and commercial CuO nanoparticles (NPs) to increase plant growth of tomato (Solanum lycopersicum) and suppress Fusarium oxysporum f. sp. lycopersici infection. The particles were foliarly applied once (500 mg/L; 1–2 mL dose) to seedlings prior to 30 days of growth. In control plants not treated by nanomaterials, Fusarium infection reduced plant growth by 62% across both experiments. Amendment with Cu3(PO4)2·3H2O nanosheets or CuO nanoparticles significantly reduced disease presence by an average of 31%, resulting in greater plant biomass. The time-dependent expression of three genes integral to plant defense (pathogenesis-related genes transcriptional activator [PTI5], polyphenol oxidase [PPO], and plant resistance protein 1A1 [PRP1A1]) was shown to be uniquely modulated by nanoscale Cu amendment. Specifically, Cu3(PO4)2·3H2O nanosheets increased the expression of all three genes in both experiments within the first 7 days of pathogen exposure, which was prior to any phenotypic evidence of disease. CuO NPs showed slower increases in the genes in the plants harvested after 21 days. Importantly, these nanoscale Cu-induced changes in expression correlated well with positive changes in disease suppression and plant growth. These results highlight the importance of adequate nutrition in crop disease response and demonstrate the potential of nanoscale platforms to more effectively deliver critical micronutrients at early stages of plant development. The transcriptomic results provide important mechanistic insight into NP Cu-based disease suppression and can be used to further optimize this important approach in nanoenabled precision agriculture.

Atmospheric aerosols are known to provide an important surface for gas-solid interfaces that can lead to heterogeneous reactions impacting tropospheric chemistry. In this work, α-Fe2O3, TiO2, γ-Al2O3, SiO2 and ZnO, common components of atmospheric aerosols, served as models to investigate the gas-solid interface of nitric acid with aerosols in the presence of simulated solar radiation. Adsorbed nitrate and gaseous products can be continuously monitored with infrared spectroscopy (IR). Kinetic studies of adsorbed species were carried out using attenuated total reflectance infrared spectroscopy (ATR-FTIR). Ex situ simultaneous infrared spectroscopy of gas-phase products using a 2 m long path cell allowed the detection of gaseous products at early stages of the heterogeneous photochemical reaction. In addition, photoactive gaseous products, such as HONO, were detected as gas analysis was carried out outside the region of irradiation. All reactions were found to be first order with respect to adsorbed nitric acid and yielded gas-phase products such as NO, NO2, N2O4, N2O, and HONO. While the correlation between semiconductor properties of the metal oxide and the heterogeneous photochemical rate constant (j) is not direct, the semiconductor properties were found to play a role in the formation of relatively high proportions of greenhouse gas nitrous oxide (N2O).