Atmospheric and Oceanic Sciences

Climate change is expected to impact rainfall amount, seasonality, and dry/wet patterns, with direct implications for rainwater harvesting systems. This study aims to quantify how future rainfall may affect rainwater harvesting systems across Brazil by combining multi-model climate projections with a daily water balance model. A single-family social housing archetype (60 m2 roof area; four occupants; 150 L/day/person; non-potable demand equal to 30% of total demand) was simulated for 652 Brazilian cities, using bias-corrected daily rainfall from the CLIMBra dataset and nineteen climate models. Historical conditions were compared with near-future and far-future projections under the SSP2-4.5 and SSP5-8.5 scenarios. Historically, the greater potential for potable water savings has occurred in wetter, less seasonal climates, such as those in the North. In contrast, more seasonal and drought-prone areas, such as the Northeast, showed lower reliability. In future climates, most models indicate relative reductions in the potential for potable water savings in the North, Northeast, and Centre–West, with larger reductions under SSP5-8.5 and in the far-future scenarios. The South shows the most significant divergence between models and may increase the potential for potable water savings in some projections. On the other hand, in the South, the volume of rainwater harvesting system overflow increases under future scenarios. This work contributes to the literature by delivering a national-scale, multi-model, uncertainty-aware evaluation of rainwater harvesting performance under non-stationary rainfall regimes.

Karst water systems are highly vulnerable to land use pressures, requiring integrated assessments to support conservation and management. This study evaluated the physicochemical, microbiological, and pesticide-related water quality in the Environmental Protection Area Nascentes do Rio Vermelho (APANRV), a karst conservation unit in the Brazilian Cerrado. Sixteen sampling sites (rivers, springs, and cave waters) were monitored during the dry (May 2024) and rainy (October 2024) seasons. Analyses included nutrients, major ions, Escherichia coli, and a broad spectrum of pesticides. The results showed marked spatial and seasonal variability, with elevated hardness and conductivity in karst areas due to carbonate dissolution. Nitrate and total phosphorus reached peak values of 13.59 and 0.132 mg L−1, respectively, indicating localized nutrient enrichment. E. coli concentrations reached ≥2419.6 MPN 100 mL−1, exceeding regulatory limits, particularly during the rainy season at recreational cave sites. Pesticides were detected in both seasons, with 11 compounds in the dry season and 8 in the rainy season, including atrazine degradation products, and maximum quantified concentrations up to 1.8 µg L−1 (acephate). These findings highlight the combined influence of geology, seasonality, and land use on karst water quality and reinforce the need for continuous monitoring and targeted management strategies.

Fenton-based processes are widely used advanced oxidation methods that are known for degrading persistent pollutants. However, these techniques often generate significant amounts of iron-containing sludge, which poses environmental disposal challenges due to its complex composition. Furthermore, the sludge produced by the Fenton process contains a high content of Fe(III) compounds, which can serve as an iron source to stimulate dissimilatory iron reduction (DIR), enhancing the performance of anaerobic digestion. Based on the characterization results from a previous study, this work investigated the use of the ferrous precipitate generated by the electrochemical peroxidation process applied to tannery wastewater treatment as an additive to enhance volatile fatty acids (VFAs) production during dark fermentation. The performance of ferrous precipitate (R-Fe3O4) was compared to that of conventional magnetite (Fe3O4) during dark fermentation under high organic loading conditions, emphasizing their potential to enhance hydrolysis efficiency and VFAs production yields, while promoting sustainable resource recovery and reuse within a circular bioeconomy framework. The results showed that the addition of both Fe3O4 and R-Fe3O4 significantly increased the VFAs yields, with a predominance of long-chain fatty acids. The presence of CaCO3 in the ferrous precipitate contributed to maintaining a stable pH environment, supporting microbial activity and enhancing the hydrolysis of soluble compounds. Moreover, the availability of essential micronutrients within the ferrous precipitate favored greater microbial diversity. Consequently, the addition of R-Fe3O4 promoted VFAs production, even at higher organic loading rates, suggesting a promising application of Fenton-based by-products as functional additives to improve the economic and environmental performance of the dark fermentation process.

Nutrient inputs from human activities, such as agriculture and sewage discharge, influence algal blooms in water bodies. In Ecuador, the Daule River receives wastewater discharges. In addition, poor agricultural practices, including the unsuitable use of fertilisers in combination with soil erosion and surface runoff processes, increase the nutrient load to the river. Considering this, the objective of this study was to evaluate environmental and biological variables using statistical analysis to identify the parameters that influence algal blooms in the main stem of the Daule River. The methodology consisted of two phases: (i) data collection, including water sampling and laboratory work for the analysis of nutrients and phytoplankton, and (ii) statistical analysis, which includes univariate, bivariate, inferential and multivariate analysis (STATICO technique). The results showed that pH and dissolved oxygen were the main drivers of diatoms (Polymyxus coronalis and Aulacoseira granulate) and the charophyte Mougeotia sp. Similarly, ammonium-N was the main driver of the diatom Ulnaria ulna and the cyanobacteria Planktothrix cf. agardhii. The outcomes of this study identified the main environmental variables driving blooms of the five most abundant species, providing a basis for the development of ecological models in the context of land use and climate change.

The Middle Jurassic represents a typical greenhouse climate period in Earth’s history, during which global carbon cycle perturbations and climatic events left significant records in continental strata. This study investigates the extremely thick coal seam of the Middle Jurassic Xishanyao Formation in the Wucaiwan mining area, Zhundong coalfield, Xinjiang, China. Through integrated coal petrological, geochemical, palynological, and organic geochemical analyses, combined with paleowildfire indicators, it aims to reconstruct the paleoenvironmental and paleoclimatic evolution sequence and explore its response to global changes. The results demonstrate that geochemical indicators and palynological assemblages collectively indicate an aridification trend in the paleoclimate. The high inertinite content and enrichment of combustion-derived polycyclic aromatic hydrocarbons in the coal attest to frequent medium-to low-temperature surface paleowildfire events during peat accumulation. On geological timescales, wildfires acted as a significant short-term carbon source, releasing vast amounts of greenhouse gases; however, over the long term, they ultimately functioned as a net carbon sink through the production of inert black carbon, facilitation of vegetation succession, and enhancement of organic matter burial. The Middle Jurassic paleoenvironmental evolution in the Junggar Basin exhibits synchronicity with global climate events, underscoring the key driving role of wildfire activity in the greenhouse Earth’s carbon cycle.

Intensified Neogene uplift of the Tibetan Plateau, acting through tectonic-climatic coupling, fundamentally reconfigured large-river systems across East and South Asia. Whereas previous studies have focused on individual catchments, this work provides the first integrated analysis of all large rivers surrounding the plateau. Multidisciplinary evidence reveals a progressive south-to-north evolutionary sequence, beginning with the establishment of the Ganges and Indus river systems (27–23 Ma), followed by integration of southeastern rivers such as the Yangtze, Mekong, and Salween (26–15 Ma), and culminating in the full basin connectivity of the Yellow River during the Early Pleistocene (∼2.6 Ma). Western endorheic systems (e.g., Tarim, Amu Darya) attained stable configurations later (15–2 Ma). Tectonics governed the resulting river typology by producing distinct genetic classes. These include intra-orogenic confined rivers such as the upper Yangtze, Mekong and Salween, transverse cross-cutting rivers including the Yarlung Zangbo and Indus, longitudinal trunk rivers exemplified by the Ganges and the lower Indus, and composite orogen-craton types. The composite types are further divided into unstable craton variants, including the Yellow River, and stable craton variants, such as the Yangtze, Amu Darya, and Tarim. Climate critically modulated this tectonic framework, with monsoon intensification enhancing incision and throughgoing connectivity in exorheic systems (e.g., upper Yangtze, Mekong, Salween), while continental aridification restricted endorheic rivers to internal drainage (e.g., Amu Darya, Tarim). This unifying framework linking tectonic, climatic, and hydrological processes not only advances mechanistic insight into Asian landscape evolution but also provides a reference for understanding tectonic-climate interactions in other orogenic plateau settings.

Landslides in the Yellow River basin are frequently triggered by periodic rainfall and groundwater fluctuations, processes that progressively degrade the mechanical properties of sliding zone soil. This study investigates the multi-scale deterioration mechanism of sliding zone soil from the Huaipa landslide in Henan Province through integrated wetting-drying cycle tests, direct shear tests, and scanning electron microscopy. The results indicate that the first wetting-drying cycle induces the most significant reduction in shear strength and cohesion. The deterioration rate subsequently decelerates with increasing cycles, tending toward stabilization after seven cycles. Microscopic analysis reveals that wetting-drying cycles initiate and propagate internal fissures, transforming micropores into larger pores and disrupting inter-particle cementation. This study elucidates the correlation between macroscopic strength decay and microscopic structural evolution, thereby providing a theoretical basis for the stability evaluation and disaster mitigation of landslides in reservoir areas.