The increasing demand for food coupled to various environmental pressures, is increasing the importance of sustainable agricultural practices. Based on results published across a wide range of disciplines, it is becoming evident that nanotechnology can play a crucial role in increasing the sustainability of agriculture, particularly in the area of fertilizer delivery, gene modification, and pest control. In this paper, we review critical plant morphological and physiological indices (pore size in xylem and phloem, xylem/phloem sap composition, xylem/phloem sap flow rate and flow conducting area) for nanoparticle (NP) transport, and examine the efficacy of various delivery methods for NPs (foliar application, root application, and feeding/injecting directly into plant tissue) with an emphasis on NP transport efficiency throughout the entire plant. While only few studies have explored the feeding/injection of NPs, these application pathways are the most efficient in terms of delivery, indicating their practical potential (e.g., for agrochemical delivery). In contrast, when applied via soil drenching or foliar spraying, the majority of the applied NPs are not taken up by the plants. However, those NPs that do penetrate the plant exhibit efficient transport from leaf to root, and vice versa. Of these two application methods, foliar application appears to be more effective in both NP delivery and transport than soil drenching. To further explain the data reported in the literature and to study the transport processes of NPs throughout the plant, we applied the Derjaguin–Landau–Verwey–Overbeek model to study the interactions of NPs with the surfaces of the plant vascular system (xylem and phloem), by which these NPs are transported throughout the plant structure. We found that the interaction energy between negatively charged NPs and plant tissue is positive, indicating that these NPs can effectively transport. We discuss future research needs regarding NP transport, which will enable effective utilization of NPs for different agricultural applications.

Pharmaceuticals and personal care products (PPCPs) are found in wastewater, and thus, the environment. In this study, current knowledge about the occurrence and fate of PPCPs in aquatic systems-including wastewater treatment plants (WWTPs) and natural waters around the world-is critically reviewed to inform the state of the science and highlight existing knowledge gaps. Excretion by humans is the primary route of PPCPs entry into municipal wastewater systems, but significant contributions also occur through emissions from hospitals, PPCPs manufacturers, and agriculture. Abundance of PPCPs in raw wastewater is influenced by several factors, including the population density and demography served by WWTPs, presence of hospitals and drugs manufacturers in the sewershed, disease burden of the population served, local regulations, and climatic conditions. Based on the data obtained from WWTPs, analgesics, antibiotics, and stimulants (e.g., caffeine) are the most abundant PPCPs in raw wastewater. In conventional WWTPs, most removal of PPCPs occurs during secondary treatment, and overall removal exceeds 90% for treatable PPCPs. Regardless, the total PPCP mass discharged with effluent by an average WWTP into receiving waters (7.35-20,160 g/day) is still considerable, because potential adverse effects of some PPCPs (such as ibuprofen) on aquatic organisms occur within measured concentrations found in surface waters.