Striking the balance: Unveiling the interplay between photocatalytic efficiency and toxicity of La-incorporated Ag3PO4.

Persistent molecules, such as pesticides, herbicides, and pharmaceuticals, pose significant threats to both the environment and human health. Advancements in developing efficient photocatalysts for degrading these substances can play a fundamental role in remediating contaminated environments, thereby enhancing safety for all forms of life. This study investigates the enhancement of photocatalytic efficiency achieved by incorporating La3+ into Ag3PO4, using the co-precipitation method in an aqueous medium. These materials were utilized in the photocatalytic degradation of Rhodamine B (RhB) and Ciprofloxacin (CIP) under visible light irradiation, with monitoring conducted through high-performance liquid chromatography (HPLC). The synthesized materials exhibited improved stability and photodegradation levels for RhB. Particularly noteworthy was the 2% La3+-incorporated sample (APL2), which achieved a 32.6% mineralization of CIP, nearly three times higher than pure Ag3PO4. Toxicological analysis of the residue from CIP photodegradation using the microalga Raphidocelis subcapitata revealed high toxicity due to the leaching of Ag + ions from the catalyst. This underscores the necessity for cautious wastewater disposal after using the photocatalyst. The toxicity of the APL2 photocatalysts was thoroughly assessed through comprehensive toxicological tests involving embryo development in Danio rerio, revealing its potential to induce death and malformations in zebrafish embryos, even at low concentrations. This emphasizes the importance of meticulous management. Essentially, this study adeptly delineated a thorough toxicological profile intricately intertwined with the photocatalytic efficacy of newly developed catalysts and the resultant waste produced, prompting deliberations on the disposal of degraded materials post-exposure to photocatalysts.

Phosphorus limitation combined with aluminum triggers synergistic responses on the freshwater microalgae Raphidocelis subcapitata (Chlorophyceae).

In the environment, algae are exposed to several stressors such as limitation of essential nutrients and excess of toxic substances. It is well known the importance of phosphorus (P) supply for healthy metabolism of algae and impacts at this level can affect the whole aquatic trophic chain. Aluminum (Al) is the most abundant metal on Earth and it is toxic to different trophic levels. Processes related to P and Al assimilation still need to be clarified and little is known about the responses of microalgae exposed to the two stressors simultaneously. We evaluated the effects of environmental concentrations of Al and P limitation, isolated and in combination, on growth, pigment production and photosynthesis of the freshwater microalga Raphidocelis subcapitata. Both stressors affected cell density, chlorophyll a, carotenoids, and maximum quantum yield. Al did not affect any other evaluated parameter, while P limitation affected parameters related to the dissipation of heat by algae and the maximum electron transport rate, decreasing the saturation irradiance. In the combination of both stressors, all parameters evaluated were affected in a synergistic way, i.e., the results were more harmful than expected considering the responses to isolated stressors. Our results indicate that photoprotection mechanisms of algae were efficient in the presence of both stressors, avoiding damages to the photosynthetic apparatus. In addition, our data highlight the higher susceptibility of R. subcapitata to Al in P-limited conditions.

Warming alters the metabolic rates and life-history parameters of Ceriodaphnia silvestrii (Cladocera).

Temperature rise has effects on the metabolic process of organisms, population structure, and ecosystem functioning. Here, we tested the effects of warming on the metabolic rates and life-history parameters of the widespread cladoceran Ceriodaphnia silvestrii. Two scenarios of global warming were established, an increase of 2 °C and an increase of 4 °C; the control temperature was 22°C. Our results showed that warming altered C. silvestrii metabolic rates, by increasing the rates of assimilation and secondary production, and decreasing the rates of filtration and ingestion. Warming also increased C. silvestrii fecundity and the body size of neonates and juveniles, and decreased the embryonic and post-embryonic time of development. C. silvestrii might be an important food resource at intermediary temperature as it had higher assimilation rates, even filtering fewer algae. At the highest temperature, we observed a substantial decrease in assimilation and secondary production, which could be a sign of stress starting. The increase in temperature by global warming will affect the cladocerans' metabolic processes and the population survival, even a small increase (2°C) might induce drastic fluctuations in such processes and affect the carbon and energy availability inside aquatic food-webs.