Tropical weather cities, such as Mérida in Yucatán, Mexico, are perceived as air pollution-free environments. This study aimed to evaluate the air quality in Mérida City over five years, focusing on PM_2.5 and PM₁₀ as well as spatial and temporal factors. A government-accredited monitoring station for PM_2.5 (2018–2022) and economic air sensors for PM_2.5 and PM₁₀ (2023) were used. Results showed the maximum daily (90 μg m⁻³) and annual PM_2.5 (23 μg m⁻³) averages for 2020 exceeded the Mexican regulations. Sensors indicated that the fixed pollution sources influenced PM_2.5 and PM₁₀. Spatially and temporally, the southwest of the city in the dry season of 2023 showed the highest PM_2.5 and PM₁₀. Tropical conditions (solar radiation and temperature) increased PM, while high humidity and precipitation decreased it. Air quality improved during the rainy season. The southwest zone had the highest density of diesel vehicles and fixed pollution sources, which contributed to the highest PM concentration. The monitoring showed that air quality related to PM in Mérida City is a concern. Local and external factors are affecting the air quality. It is mandatory to regulate air emissions from fixed sources and implement vehicle verification, even in tropical weather cities.

The environmental persistence of post-consumer plastics remains a critical challenge due to their chemical stability, the presence of additives, and prior environmental weathering. This study evaluates the partial biodegradation and chemical transformation of post-consumer low-density polyethylene (LDPE) and expanded polystyrene (EPS) by Tenebrio molitor larvae under uncontrolled environmental conditions. Four diets were tested, including LDPE+S and EPS+S (polymers supplemented with wheat bran), to assess the influence of a co-substrate on larval performance and polymer transformation. Fourier-transform infrared spectroscopy (FTIR) revealed the emergence of oxygen-containing functional groups (–OH and C=O) in the frass, which were absent or negligible in pristine materials, indicating oxidative modification of the polymer matrix. Gel permeation chromatography (GPC) revealed pronounced reductions in number-average molecular weight (Mn) and increased polydispersity for EPS-derived fractions, consistent with heterogeneous chain scission and partial depolymerization. For LDPE, GPC evidenced the formation of THF-soluble, low-molecular-weight polymer-derived fragments, indicating fragmentation despite the inability to quantify pristine LDPE due to its insolubility in the mobile phase. Gas chromatography–mass spectrometry (GC–MS) identified aromatic hydrocarbons, phthalate esters, organosiloxanes, and fatty acid derivatives, reflecting both degradation intermediates and migrated additives from post-consumer plastics. Together, these results provide integrated evidence that Tenebrio molitor can induce chemical transformation of post-consumer LDPE and EPS under non-controlled environmental conditions, offering mechanistic insight into a biologically mediated degradation pathway that is directly relevant to realistic plastic waste scenarios.

Irrigation with pig slurry has been employed to discharge large volumes of slurry and to recover resources. However, using swine wastewater for agricultural irrigation may cause the accumulation of heavy metals in soil and their potential leaching to groundwater. Wastewater treatment plants (WWTPs) are crucial to mitigate heavy metal contents in swine wastewater through physical, chemical, and biological processes. This study tracked the fate of eight heavy metals in industrial swine farms: arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), mercury (Hg), nickel (Ni), and zinc (Zn). Zn reported the highest removal (82 to 99%) in all WWTPs and Cu the lowest (−5 to 97%). Cu (0.59–1.64 mg L⁻¹) and Zn (0.35–1.14 mg L⁻¹) were the metals reported in all samples for the target treatment stages (influent, after biodigester, and effluent). Comparing the heavy metal concentration in the effluents, Cu and Zn reached the highest concentrations in all WWTPs. As, Cd, and Pb reported values under the practical quantification limit. In groundwater, Cr reported the highest average concentration in farm GP19 for upstream (0.006 mg L⁻¹) and for downstream (0.032 mg L⁻¹) in GP1. In irrigated soil the Cu and Zn reported the highest concentrations in all farms, showing an enrichment compared to natural soil, indicating that wastewater is the main source of these metals in soil in the farm areas. Although all metals met the Mexican and international regulations, total suspended solids (TSSs) and chemical oxygen demand (COD) for effluent were above the reference limits (TSS ≤ 24 mg L⁻¹ and COD ≤ 72 mg L⁻¹) more than ten and four times, respectively, for all WWTPs evaluated. These two parameters were positively related and significantly correlated (p < 0.05) with the presence of metals in the different water fractions, implying possible transport of metals in solids. Cd, Pb, and As, were never reported in treated wastewater and groundwater, but Cr and Hg were. This may be related to external activities such as agriculture for Cr. The enrichment of metals in irrigated soils can be related to the metal presence in groundwater due to leaching because of the karstic soil in the area.

The increasing demand for food has led to rise in both swine and agricultural production. However, pig farming contributes significantly to environmental pollution. Swine wastewater is rich in nutrients and can serve as an alternative source of fertilization for plants. This study evaluated the effects of swine wastewater on the distribution and con-centration of essential and non-essential elements, and morphology of habanero pepper (Capsicum chinense Jacq.) seedlings. Seedlings were irrigated with varying concentrations of swine wastewater: T1= 20% wastewater + 80% water; T2= 40% wastewater + 60% water; T3= 60% wastewater + 40% water; T4= 80% wastewater + 20% water; T5= 100% wastewater; T6= control (100% water with conventional fertilization). The experiment fol-lowed a completely randomized design with five replications. Parameters measured in-cluded seedling emergence, distribution and concentration of essential and non-essential elements, morphological characteristics, and seedling quality were measured. Emergence percentage and rate were highest in T1 and T6. Potassium and calcium showed excellent distribution and concentration in seedlings, under diluted wastewater treatments, pro-moting better growth. In contrast, irrigation with 100% wastewater increased chlorine and sulfur accumulation, negatively affecting morphology. Diluted swine wastewater im-proved elemental availability, seedling emergence, and growth. Thus, using diluted swine wastewater, particularly at 20%, presents a viable alternative for the production of high-quality habanero pepper seedlings.

The growing global demand for food has driven an increase in both swine and agricultural production, although swine wastewater poses a significant environmental risk. This study employed elemental mapping techniques to evaluate the effects of swine wastewater irrigation on the spatial distribution and concentration of essential and non-essential elements, as well as on the morphological responses of habanero pepper (Capsicum chinense Jacq.) seedlings. Six treatments were tested, ranging from 0% to 100% swine wastewater (T1 = 20%, T2 = 40%, T3 = 60%, T4 = 80%, T5 = 100%, and T6 = control with conventional fertilization), using a completely randomized design with five replications. Emergence, elemental distribution, morphology, and seedling quality were evaluated. The highest emergence percentages and rates were observed in the 20% wastewater treatment and the control groups. Diluted wastewater treatments promoted potassium and calcium uptake, which correlated with improved seedling growth and vigor, while irrigation with 100% wastewater led to excessive chlorine and sulfur accumulation, negatively affecting morphology. These results indicate that the controlled dilution of swine wastewater optimizes nutrient availability and seedling development, offering an environmentally sustainable alternative for producing high-quality habanero pepper seedlings. This study provides novel insights into the environmental implications of swine wastewater reuse through elemental mapping, underscoring its potential to support sustainable and regenerative agriculture.