Water eutrophication is a global environmental problem that poses serious threats to aquatic ecosystems and human health. The evaluation of eutrophication provides a theoretical basis and technical guidance for the management and rehabilitation of water ecosystems. In the last four decades, dozens of evaluation methods have been applied to freshwater eutrophication, but there is a clear need to optimize and standardize the most suitable methods. We have addressed this gap by presenting a systematic review of methodologies. Due to the diversity and complexity of water bodies, no single evaluation method was identified that would adequately represent eutrophication under all scenarios. We demonstrate that lakes can best be assessed using the trophic level index (TLI) method, reservoirs and wetlands the trophic state index (TSI) and fuzzy comprehensive evaluation (FCE) method, respectively, and rivers the FCE method or back propagation (BP) neural network methods. More recently applied methodologies including spectral imaging and 3-D mapping of water quality using underwater gliders allow greater resolution and can be effective in managing waterbodies to avoid future eutrophication. The aim of this review is to guide future studies on the most appropriate methods available for assessing and reporting water eutrophication.

In light of external bias potential separating charge carriers on the photocatalyst surface, piezo materials’ built-in electric field plays a comparable role in enhancing photocatalyst performance. The synergistic effect provided by combining piezo materials assures the future of photocatalysis in practical applications. This paper discusses the principles and mechanisms of piezo-photocatalysis and various materials and structures used for piezo-photocatalytic processes. In piezo-photocatalyst composites, the built-in electric field introduced by the piezo component provides bias potential and extracts photocatalytically generated charge carriers for their subsequent reaction to form reactive oxygen species, which crucially affects the catalytic performance. In the composites, the shape and structure of substrate materials particularly matter. The potential of this technology in other applications, such as energy generation and environmental remediation, are discussed. To shed light on the practical application and future direction of the technique, this review gives opinions on moving the technique forward in terms of material development, process optimization, pilot-scale studies, comprehensive assessment of the technology, and regulatory frameworks to advance practical applications, and by analyzing its principles, applications, and challenges, we hope to inspire further research and development in this field and promote the adoption of piezo-photocatalysis as a viable treatment method for treating emerging pollutants in wastewater.

This study was conducted in order to study the effect of different concentrations of lead pollution on the photosynthetic characteristics and growth of Miscanthus floridulus, and to reveal its photosynthetic adaptability to lead stress. The differences of gas exchange parameters, chlorophyll fluorescence characteristics and photosynthetic pigment of two Miscanthus floridulus populations, one population from Boluo an uncontaminated site, and another population from Dabaoshan, a mine site, were compared and studied through nutrient solution culture experiments treated with heavy metal lead (Pb) in green house. The results showed that (1) under Pb stress, the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), intercellular carbon dioxide concentration (Ci), and chlorophyll content (Chl) of the leaves of the two populations decreased in different amplitude. Under moderate and severe Pb stress (80 mg·L⁻¹, 120 mg·L⁻¹, 240 mg·L⁻¹), the plant biomass of non-mining population and mining population plants were 54.5%, 39.7%, 29.4% and 70.4%, 54.7%, 50.9% of the control, respectively. (2) Stomatal restriction was the main factor for the Pn’s decrease in the leaves of the non-mine population under light Pb stress, while the non-stomatal restriction was the main factor for Pn’s decrease in the leaves of the non-mine population under middle and high Pb stresses. (3) Under Pb stress, the maximum photochemical efficiency (Fv/Fm) and potential activity (Fv/Fo) of PS II reaction centers in the two populations of M. floridulus decreased. However, Fv/Fm and Fv/Fo showed a smaller decrease, but the capability to utilize light and the potential to activate PSII of the mine population remained higher than that of the non-mine population. The changes of photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (NPQ) of PSⅡ showed that qP value decreased and NPQ value increased in the two populations under Pb stress. On the whole, the resistance mining area population had a low qP reduction and a large increase in NPQ. Electronic transfer rate (ETR) and PSII actual fluorescence efficiency (ΦPSII) of the mine population changed slightly under Pb stress. These results indicated that when under Pb stress, the electron transport activity and photosynthetic apparatus were damaged less in the mine population with high resistance than in the non-mine population with low resistance. Conclusion: the mining population of M. floridulus has strong tolerance to Pb, which is suitable for the pioneer species of gramineae in vegetation restoration construction in metal mining area.

Ag nanoparticles loaded onto TiO₂ nanosheets with exposed {001} facets were synthesized by solvothermal hydrolysis and photoreduction deposition methods. The results suggested that Ag NPs were uniformly dispersed on the surface of anatase TiO₂ NSs with a metallic state. The Raman scattering and visible light absorption performances of Ag/TiO₂ NSs were enhanced by Ag NPs due to their surface plasmon resonance effect. Photocatalytic oxidation experiments for HCHO were carried out under visible light, and the enhanced photocatalytic activity of Ag/TiO₂ NSs can be attributed to the synergistic effects of the following factors: (1) the {001} facets, which possessed higher surface energy, showed higher photocatalytic activity; (2) the Ag NPs, the increased oxygen vacancies, and O₂ adsorption on {001} facets can trap photoelectrons, thus inhibiting the recombination of photoelectrons and holes; (3) the Ag NPs can extend the light response range of TiO₂ into visible light. The in situ FTIR results showed that higher mineralization efficiency of HCHO was achieved on Ag/TiO₂ NSs than on Ag/TiO₂ NPs. Additionally, the mechanism for HCHO photocatalytic oxidation was also discussed.