Atmospheric and Oceanic Sciences

This study presents a life cycle assessment of a low-cost pilot-scale wastewater treatment system that combines solar photocatalytic oxidation with Nature-based Solutions (NBSs) for a specially constructed wetland (CW). The prototype was designed and assessed for its efficiency in treating urban wastewater and its environmental impact on agricultural irrigation reuse. Evaluations were performed with the SimaPro software, applying the Impact ReCiPe Medpoint methodology, which includes characterization and selection of the relevant environmental issues steps. The results demonstrate the potential of this hybrid system for providing high-quality treated wastewater suitable for agricultural reuse in water-scarce regions. The analysis reveals that the operational phase, mainly driven by energy consumption for pumping, aeration, and photocatalytic processes, accounts for over 85–98% of the total global warming potential (GWP), primarily due to reliance on fossil-based electricity. Conversely, the construction phase significantly impacts land use and toxicity categories, with concrete and substrate production contributing around 95% to land occupation and 97% to human toxicity. The photocatalytic subsystem also contributes notably to embodied carbon at 42.4%, owing to energy-intensive manufacturing. The results underscore the importance of optimizing operational energy efficiency and selecting sustainable materials to mitigate environmental burdens. The integrated system demonstrates promising potential for producing high-quality treated effluent suitable for agricultural reuse in water-scarce regions, supporting sustainable water management. These findings provide important insights for reducing ecological impacts and advancing environmentally sustainable wastewater treatment solutions.

Nowadays, river systems exhibit significant geomorphic changes that primarily reflect their response to the climate signal, driven by ongoing climate change. In this context, detecting future trends in riverbed dynamics is crucial, especially from a river management perspective. The purpose of the study is to identify long-term trends in riverbed evolution at the Băleni gauging station on the Ialomița River, based on the channel-forming discharge concept, through the end of the 21st century. To achieve this, a comprehensive methodology was developed that primarily focuses on calculating the effective discharge (Qe) as a key driver of riverbed dynamics, using discharges simulated by the E–HYPE hydrological model forced by eight EURO–CORDEX EUR–11 ensemble climate projections under the RCP 4.5 and RCP 8.5 scenarios up to 2100. The results of the study indicate Qe values ranging between 7.49 m3/s and 12.79 m3/s for RCP 4.5, and between 5.66 m3/s and 13.94 m3/s for RCP 8.5. Based on the ensemble mean of Qe, different riverbed evolution trends and are identified: a state of dynamic equilibrium under RCP 4.5, suggesting that the riverbed is probable to maintain its geomorphological state similar to the present; and pronounced variability under RCP 8.5, indicating intense erosion processes until mid-century, followed by a slight aggradation trend that may intensify at the end of the century, with Qe being 23.27% lower than the reference period. Overall, the Qe8.5 evolution suggests a potential future alteration of the Ialomița riverbed. Beyond its main findings, this study provides a methodological framework for assessing future effective discharge and may support river management and restoration planning in the study area.

Inland waters exhibit pronounced temporal variability in CO2 and CH4 emissions. However, existing research has predominantly focused on seasonal to interannual scales, with most field measurements conducted during daytime hours. Consequently, diel (24 h) emission dynamics remain poorly characterized. This study synthesizes current knowledge on diel variations in CO2 and CH4 fluxes across inland water bodies—including rivers, lakes, reservoirs, and ponds—with particular attention to day–night contrasts. Based on the limited available data, the average day-to-night flux ratios are 0.87 for CO2 and 1.44 for CH4. Exclusive reliance on daytime sampling may therefore underestimate daily CO2 emissions by approximately 13% while overestimating CH4 emissions by a similar magnitude. Diel fluctuations in water temperature and wind speed—driving corresponding changes in surface water gas concentrations and air–water gas transfer velocity—represent primary controls on these emission patterns. Secondary influences include solar radiation, dissolved oxygen, pH, and nutrient availability. Future efforts should prioritize high-frequency monitoring of diel carbon emission cycles and mechanistic analysis of their drivers, ultimately enabling the development of large-scale models that explicitly incorporate diel dynamics. Such advances are essential for accurate quantification and correction of carbon emissions from inland waters at regional to global scales.

A typical Tamarix nebkha was studied in the southern Qaidam Basin, China. K-feldspar pIRIR dating was applied to establish a reliable chronological framework, and an Undatable age–depth model was constructed. Accumulation rates (AR) declined in stages: rapid (~1.33 cm/a; ~370–260 yr BP), slower (~0.75 cm/a; ~260–130 yr BP), and slowest (~0.31 cm/a; ~130 yr BP-present). This dynamic pattern is likely influenced by a combination of regional aeolian activity variations, geomorphological evolution, and the intrinsic growth dynamics of the nebkha itself. To further understand the relationship between nebkha development and climatic conditions, a δ13C sequence was reconstructed using Tamarix plant remains preserved within the sediments. Based on shifts in leaf-level δ13C values, which indicate changes in water use efficiency, water availability over the past 370 years was inferred and divided into three main phases: relatively sufficient from 1650 to 1690, gradually decreasing during 1690–1870, and increasing again after 1870. The δ13C trend closely correlates with temperature variations derived from δ18O records of the Malan ice core. This suggests that in this hyper-arid region, the development of Tamarix nebkhas is primarily controlled by glacial meltwater and snowmelt runoff from the Kunlun Mountains, rather than by local precipitation.

High-latitude and cold-region environments feature tightly coupled hydrological, cryospheric, and ecological subsystems, where seasonal freeze–thaw cycles, snow cover, permafrost, and river and lake ice fundamentally shape water flows and ecosystem processes [...]

Community water systems in the United States provide drinking water to more than 300 million people annually, making their reliability fundamental to public health. In regions with long histories of racial segregation and unequal infrastructure maintenance, water system failures can deepen existing environmental injustices. This study examines water quality conditions in the Jackson, Mississippi, metropolitan area following the 2022 distribution system collapse and a decade of repeated noncompliance with the Safe Drinking Water Act’s Lead and Copper Rule (LCR). Using the U.S. Environmental Protection Agency’s 2024 updated LCR tap sampling protocol, water samples from 29 sites were collected. Samples were analyzed for lead, copper, iron, zinc, chlorine, sulfate, pH, and total dissolved solids concentrations. Chlorine-to-sulfate mass ratios (CSMR) were also calculated to evaluate corrosion potential. Demographic surveys, statistical analyses, and geospatial visualizations were used to interpret neighborhood-level patterns. Our findings show that all sites met primary drinking water standards and complied with LCR action levels but exceeded secondary drinking water standards at 100% of study sites. Seven sites exhibited CSMR values above the threshold, indicating increased susceptibility to corrosion. These results highlight the need for targeted corrosion control, treatment optimization, and ongoing monitoring, particularly in historically marginalized communities.

We conducted a long-term assessment of how natural free-water surface (FWS) wetlands respond to sustained loads of partially treated municipal effluent. We quantified the effects on vegetative cover, ammonium concentration, and fecal coliform bacteria densities and compared them to constructed wetlands with hydrologically defined flows. Variations in the area of open water and floating vegetation converted from emergent marsh, shrub or bottomland hardwood forest (0 to 124.6 ha) were directly proportional to the nitrogen loading at all eight sites (range 5.4 to 24.6 thousand Kg N yr−1). Trees exposed to effluent at five locations sometimes died in the first year, or they took decades to die. At the one location with fecal coliform data, their densities were directly related to ammonium concentrations, which were within the concentration range of untreated municipal sewage water. Ammonium levels exceeded US EPA chronic toxicity standards at three locations and aquatic toxicity levels developed by independent scientists at all eight locations. The loss of organic peat and habitat has multiple consequential effects that may be quick to happen or subtle, and be slow to restore, if at all. Compared to constructed wetland treatment systems, FWS systems are more difficult to constrain, have much reduced predictabilities and bring unwelcome consequences.

Flood simulation in small- and medium-sized catchments is hindered by data scarcity and strong hydroclimatic heterogeneity. Distributed models with pedotransfer functions offer new opportunities, yet their parameter sensitivity and regional applicability remain insufficiently understood. In this study, the wflow_sbm model was applied to two catchments: the humid Tunxi basin and the semi-humid Chenhe basin, China. Model seamless parameters, defined as spatially continuous fields derived directly from global datasets using pedotransfer functions without local calibration, were generated using the HydroMT system. The parameter sensitivity, applicability of pedotransfer function derived parameters, and model performance were systematically evaluated and benchmarked against the well-established Xin’anjiang (XAJ) model, which is a conceptual lumped hydrological model widely used for flood simulation in humid and semi-humid regions of China. Sensitivity analysis identified KsatHorFrac and InfiltCapSoil as dominant in Tunxi, and KsatHorFrac and SoilThickness in Chenhe. SoilThickness derived by HydroMT underestimated flood volumes in the Chenhe basin but was substantially improved after applying a uniform scaling factor of 0.1, resulting in an effective SoilThickness of approximately 0.2 m. The wflow_sbm model achieved performance comparable to the XAJ model. Optimal calibration achieved NSE = 0.85 in Tunxi with good performance at internal sub-catchments (Yuetan and Chengcun, NSE > 0.70), and generally above 0.7 in Chenhe. These findings highlight the region-dependent validity of parameterization and provide guidance for distributed flood modeling in data-scarce basins.

This study, based on stable hydrogen and oxygen isotope observations of multiple water bodies (precipitation, river water, soil water, and groundwater) in the Ami Dongsou alpine arid watershed on the southern slope of the Qilian Mountains during 2023–2024, reveals significant seasonal fluctuations in water isotope characteristics and water source renewal mechanisms. The results show that precipitation and soil water exhibit notable enrichment during the dry season, primarily due to enhanced evaporation causing light isotopes to evaporate and heavy isotopes to accumulate. River water, influenced by both precipitation recharge and evaporation, shows smaller seasonal fluctuations. Groundwater isotopes remain stable, reflecting a slower water source renewal process with minimal seasonal influence. Through quantitative comparisons of the evaporation line’s slope and intercept, this study finds that precipitation is most significantly affected by evaporation, while groundwater is least influenced, showing more stable isotope characteristics. Climate and topography in high-altitude areas significantly regulate water isotope characteristics, especially during the dry season, where evaporation plays a dominant role in the enrichment of precipitation and river water isotopes. This study innovatively establishes an evidence framework for the linkage of multiple water body isotopes, revealing the “seasonal strong fluctuations + differential water body responses + high-altitude regulation” mechanism of water isotopes in alpine arid regions. It provides new data support for water resource management, particularly in aspects such as water source allocation during the dry season, groundwater protection, and evaporation enrichment effect prediction. Future research could expand the sample size and integrate multi-source data and hydrological models to further improve the accuracy of hydrological process predictions, offering more precise support for watershed water resource management and ecological protection.

This study systematically evaluated the response mechanisms of water and sediment processes in the Kuye River Basin to climate change and human activities from 2023 to 2053 by integrating multi-source climate scenarios (CMIP5 models), land-use change projections (based on the Markov chain model), and a distributed hydrological model (SWAT model). The results indicate that under the RCP8.5 high-emission scenario, annual precipitation in the basin shows a non-significant increasing trend but with intensified interannual variability. Spatially, precipitation exhibits a pattern of increasing from northwest to southeast, with a marked decadal transition occurring around 2043. Land-use structure undergoes significant transformation, with construction land projected to account for 30.54% of the total basin area by 2050, while grassland and cropland continue to decline. Water and sediment processes display distinct phased characteristics: a fluctuating adjustment phase (2023–2033), a relatively stable phase (2034–2043), and a sharp growth phase (2044–2053). Parameter sensitivity analysis identifies the curve number (CN2) and soil bulk density (SOL_BD) as key regulatory parameters, revealing the synergistic mechanism by which land-use changes amplify climatic effects through alterations in surface properties. Based on the findings, an adaptive watershed management framework is proposed, encompassing dynamic water resource regulation, spatial zoning, targeted erosion control, and iterative scientific management. Particular emphasis is placed on addressing hydrological transition risks around 2043 and promoting low-impact development practices in high-erosion areas. This study provides a scientific basis for the integrated management of water and soil resources in the context of ecological conservation and high-quality development in the Yellow River Basin. The methodology developed herein offers a valuable reference for predicting water and sediment processes and implementing adaptive management in similar semi-arid basins.

The study investigates the projected impact of climate change on water runoff in the upper Parsęta catchment, a postglacial lowland basin located in northwestern Poland. In the first step of the analysis, hydrological simulations for the period 2005–2022 were conducted using the Soil and Water Assessment Tool (SWAT). Model calibration and validation, performed in SWAT-CUP with the SUFI2 algorithm, yielded satisfactory performance (R2 = 0.66–0.80; PBIAS = 0.43–13.87). Based on the calibrated model, projected simulations were performed for three future decades (2021–2030, 2031–2040, and 2041–2050) under two Representative Concentration Pathways (RCP4.5 and RCP8.5). Climate input data were derived from the KLIMADA 2.0 national database, which was developed using down-scaled regional climate model output from the EURO-CORDEX ensemble and statistical bias-correction methods to generate high-resolution projections. Under RCP4.5, mean annual runoff increased by approximately 13–26%, while under RCP8.5, the changes were more variable, ranging from 2% to 28% relative to the 2011–2020 baseline. Seasonal analyses revealed enhanced autumn–winter runoff and lower spring–summer flows. The findings highlight that moderate climate forcing can lead to substantial alterations in hydrological regimes in postglacial lowland catchments, in certain decades comparable in magnitude to those projected under extreme forcing, underscoring the need for adaptive water management in northern Poland.

Ice cores retrieved from the Third Pole provide invaluable information about past and present environmental changes. Here we present, for the first time, a continuous tritium and plutonium isotope profile of the Puruogangri ice field, Tibetan Plateau, China, for the last 70 years. The age-depth profile has been composed by different time anchors such as the onset of thermonuclear weapon tests, the so-called bomb peak of tritium, the Chernobyl event, and the time of ice coring. The accumulation rate of ice calculated from the age-depth relation shows a decrease after 1963. It was 57, 15, and 22 cm/year in the periods of 1954–1963, 1963–1986, and 1986–2023, respectively. The concentrations of plutonium isotopes (239Pu: up to 2.7 fg/g) are slightly lower than those of the Belukha ice core, Siberian Altai, Russia, and almost the same as the Miaoergou glacier, eastern Tien Shan, China. Contrary to this latter ice core profile, the Puruogangri plutonium profile reflects that the Chinese weapon test started in 1966. This is confirmed by the tritium time series as well. 240Pu/239Pu atomic ratios vary between 0.14 and 0.23, with an average of 0.177 ± 0.024. The overall obtained local fallout of 239Pu and 240Pu is 13.2 and 9.0 Bq/m2 (4.0 and 1.1 ng/m2), respectively.