Most rivers in developed regions receive tertiary-treated effluents from wastewater treatment plants that still contain a complex mixture of pollutants, but their combined effects on food webs are poorly understood. We had the unique opportunity to divert treated effluent into a previously pristine stream and conduct a before-after/control-impact/paired experiment to quantify effluent effects on green and brown food web pathways (i.e., algae and detritus-based pathways) and total food chain length. We hypothesized that the increased biofilm biomass after the effluent addition would promote its consumption by primary consumers, thus favoring the green pathway. Moreover, we hypothesized that the increase in the primary production would lead to an increase in food chain length. Coarse detritus remained the main food resource for primary consumers, but the addition of the effluent promoted biofilm biomass and increased the relative importance of the green food web pathway. However, the effluent discharge did not impact food chain length. The present study reveals that properly treated and substantially diluted effluents can still affect food web pathways through changes in dietary composition of consumers. Thus, further reducing nutrient inputs from WWTPs would minimize the impacts of effluents on food webs.
Investigating Late-Holocene climate variability in the Mediterranean, one of the most climatically sensitive regions, provides key insights into past environmental dynamics. The Halk El Menjel Lagoon, a key paleoenvironmental archive in the south-central Mediterranean, preserves a 4400-year sedimentary record (HK2) that reflects both regional and global climate changes. The chronology of the core is constrained by three AMS radiocarbon dates obtained specifically for this study and integrated into a Bayesian age–depth model using the rBchron package. Grain-size analysis of 750 samples from a 150 cm sediment core identified 12 subpopulations (1.2–2 to 1000–1350 µm), which were grouped through Principal Component Analysis and distribution analysis into three main transport modes: aeolian (600–1000 µm), fluvial (250–580 µm), and hydraulic runoff (1.2–2 µm). Temporal trends reveal major sedimentary shifts corresponding to well-known climatic phases. The Iron Age interval, encompassing the 2.8 ka BP event, shows pronounced variability in grain-size distributions, indicating an overall trend toward increasing aridity. The HK2 record displays a synchronous reduction in the 250–580 µm fluvial subpopulation, alongside the emergence of a finer 40–62 µm subpopulation, suggesting reduced fluvial energy and relatively humid conditions compared to other arid Mediterranean records. The Roman Humid Period appears as a phase of marked humidity (250–580 µm reaching 54.7% and 2–5.2 µm at 4.1%), punctuated by highly energetic storm events (1000–1350 µm, 1.9%) and interrupted by significant arid episodes (600–1000 µm, 36.3%), revealing alternating depositional regimes. In contrast, the Dark Age and Medieval Climate Anomaly emerge as climatically temperate phases, highlighting a regional pattern that differs from other Mediterranean records. The Modern Period is dominated by fine-grained runoff deposits (>99% 1.2–2 µm), reflecting a confined, low-energy lagoonal setting.
This study explores the extraction potential of PCP, its ester derivative (PCP1), and its acid derivative (PCP2) towards uranium-238 from aqueous solutions. Preliminary tests revealed that PCP2 exhibits the highest extraction efficiency. Doehlert experimental design was applied to optimize solution pH and ligand mass. Optimal conditions were identified as pH 2.65 and 86.45 mg of PCP2, yielding extraction efficiency up to 85.93
The contamination of water by uranium poses a serious threat to ecosystems and human health, creating a need for efficient and selective remediation strategies. Supramolecular materials, with their pre-organized structures, offer a promising route for uranium removal. Phenoxycalix[4]pyrroles (PCP) are well-known supramolecular scaffolds capable of selective metal binding, making them attractive candidates for designing uranium extractants. Here, we report the design and synthesis of PCP HA, a phenoxycalix[4]pyrrole scaffold functionalized with four hydroxamic acid (HA) groups, and evaluate its uranium(VI) extraction potential. PCP HA was synthesized from its ester precursor (PCP E) via hydroxyaminolysis using KOH, achieving a 95% yield. Its structure was confirmed by 1H NMR, 13C NMR, and HRMS. The uranium(VI) extraction efficiency of PCP HA was evaluated by solid-liquid extraction experiments, using uranyl acetate as the uranium source, with measurements performed by gamma spectroscopy. PCP HA demonstrated good performance, removing up to 95% of uranyl(VI) from aqueous solutions (1 mM) at acidic pH, likely due to the strong coordination provided by its hydroxamic acid groups. Further studies revealed that the extraction efficiency also depends on the ligand-to-metal molar ratio. These findings establish PCP HA as a promising supramolecular material for the removal of uranyl from aqueous media.
Abstract Reconstructing global temperatures from sparse proxy data remains a key uncertainty in paleoclimate science. Here, we apply an emergent constraint framework that combines statistical relationships from paleoclimate model simulations with proxy‐based estimates to infer unknown climate variables. We compiled a new multiproxy data set of tropical land temperature reconstructions for the Last Glacial Maximum (LGM), which implies tropical terrestrial cooling of −4.2°C (−5.0 to −3.5°C, 95% Confidence Interval, CI). Applying our emergent constraint framework to this terrestrial temperature reconstruction, we derived updated estimates of tropical sea surface temperature (−2.6°C; −3.3 to −2.0°C, 95% CI) and global mean surface temperature (−5.4°C; −6.5 to −4.4°C, 95% CI). These observation‐based estimates support LGM cooling toward the colder end of published ranges, implying that very low equilibrium climate sensitivity (ECS < ∼3°C) is unlikely. Our method is adaptable for different time periods and climate variables, providing a flexible framework for integrating proxy and model information.
