The podzol-ferralsol soil systems, which cover great areas of Amazonia and other equatorial regions, are frequently associated with kaolin deposits and store and export large amounts of carbon. Although natural organic matter (NOM) plays a key role in their dynamics, little is known about their biogeochemistry. In order to assess the specific role of dissolved organic matter (DOM) on NOM storage in deep horizons and to determine possible relationships between kaolin formation and DOM properties, we studied the groundwater composition of a typical podzol-ferralsol soil catena from the Alto Rio Negro region, Brazil. Groundwater was sampled using tension-free lysimeters placed according to soil morphology. DOC, E_H, pH, and dissolved Si, Al³⁺, Fe²⁺, and Fe³⁺ were analyzed for all samples and values are given in a database. Quantification of other dissolved ions, small carboxylic acids and SUVA₂₅₄ index and acid-base microtitration was achieved on selected samples. Part of the DOM produced by the hydromorphic podzols is directly exported to the blackwater streams; another part percolates at greater depth, and more than 90% of it adsorbs in the Bh-Bhs horizons, allowing carbon storage at depth. Humic substances are preferentially adsorbed with regard to small carboxylic compounds. With regard to kaolin genesis, kaolinite precipitation is favored by Al release from NOM mineralization within the Bh-Bhs and kaolin bleaching is ensured by iron reduction due to acidity and relatively low E_H. Fe²⁺ mobility can be related to small E_H variations and enhanced by the significant concentration of small carboxylic acids. The long-term result of these processes is the thickening of the kaolin, and it can be inferred that kaolin is likely to occur where active, giant podzols are close to a slope gradient sufficient enough to lower the deep water table.

The lower spatial resolution of thermal infrared (TIR) satellite images and derived land surface temperature (LST) is one of the biggest challenges in mapping temperature at a detailed map scale. An extensive range of scientific and environmental applications depend on the availability of fine spatial resolution temperature data. All satellite-based sensor systems that are equipped with a TIR detector depict a spatial resolution that is coarser than most of the multispectral bands of the same system. Certain studies may therefore be not feasible if applied in areas that depict a high spatial variation in temperature at small spatial scales, such as urban centers and flooded pristine areas. To solve this problem, this study applied an image downscaling method to enhance the spatial resolution of LST data by combining TIR, multispectral images, and derived data, such as Normalized Difference Vegetation Index (NDVI), according to the geographically weighted regression (GWRK) and area-to-point kriging of regressed residuals. The resulting LST images of the natural and anthropogenic urban areas of the Brazilian Pantanal are very highly correlated to the reference LST images. The approach, combining ASTER TIR with ASTER visible/infrared (VNIR) and Sentinel-2 images according to the GWRK method, performed better than all of the remaining state-of-the-art downscaling methods.

Studies on the environmental impact of nanoplastics face challenges in plastic analysis and a scarcity of nanoplastic materials necessary for the development of analytical techniques and experiments on biota impact. Here we provide detailed procedures for obtaining nanoparticles suspended in water for the most commonly used polymers: Polypropylene (PP), Polyvinylchloride (PVC), Low- and High-Density Polyethylene (PE-LD, PE-HD), and Polystyrene (PS). We dissolved larger size material to reprecipitate nanoparticles. For all plastic types, we obtained nanoparticles with a size between 50 and 300 nm, and a mainly spherical morphology. We verified that no irreversible agglomeration or coalescence of the particles occurred after 5 days of storage. The concentrations obtained in the final carrier solution were of the order of 10⁹ particles mL⁻¹. To prevent the persistence of reagents in the final carrier solution, a filtration step was implemented at the end of the process. The method proved unsuitable for Polyethylene Terephthalate (PET).

Soil porosity, especially pore size distribution, is an important controlling factor for soil infiltration, hydraulic conductivity, and water retention. This study aimed to verify the effect of secondary-treated domestic wastewater (STW) on the porosity of a sandy loam Oxisol in the city of Lins, state of São Paulo, Brazil. The two-year experiment was divided into three plots: soil cultivated with corn and sunflower and irrigated with STW, soil cultivated and irrigated with sodic groundwater, and non-irrigated and non-cultivated soil (control). At the end of the experiment, undisturbed core samples were sampled from 0 to 2.0 m (8 depths). The water retention curves were obtained by tension plates and Richard's pressure plate apparatus, and the pore size distribution inferred from the retention curves. It was found that irrigation with treated wastewater and treated groundwater led to a decrease in microporosity (V MI), defined as the pore class ranging from 0.2 to 50 μm diameter. On the other hand, a significant increase in cryptoporosity (V CRI) (< 0.2 μm) was identified throughout the soil profile. The presence of Na+ in both waters confirmed the role of this ion on pore size distribution and soil moisture (higher water retention).

Advancements in microplastic research are progressing rapidly, yet detecting and identifying nanoplastics remain challenging, especially in natural samples. In this study, we addressed these challenges by employing fluorescent labeling on nanoparticles of six prevalent plastic types (PP, LDPE, HDPE, PS, PET, and PVC) to enable their specific detection via the analysis of 3D fluorescence spectra post-staining. Four fluorescent molecules were tested: cyanine-3 phosphoramidite, rhodamine-6G, fluorescein sodium salt, and Vat Red 15. Our observations indicated that adsorption onto nanoplastic particles resulted in peak shifts in the fluorescence signal, providing sufficient specificity for nanoplastic identification. Among the tested fluorophores, fluorescein was the most effective, successfully discriminating PP, PVC, HDPE, LDPE, and PS. Rhodamine-6G produced shifted signals for HDPE, LDPE, and PS but grouped them together. Cyanine-3 effectively distinguished PVC, PS, and PET, while Vat Red was only able to discriminate PVC.