Search Results (11)

Polluted water in the Chapala–Santiago basin (CSB) contains several genotoxic substances that present risks to human health, particularly among residents of communities surrounding Lake Chapala and the Santiago River, where a high prevalence of cancer has been documented. For this reason, it is necessary to study the genotoxic activity of these waters and the genetic damage in inhabitants of the surrounding populations. This study assessed the genotoxicity of water in various communities in the CSB and evaluated DNA damage to lymphocytes in residents of nearby locations. The alkaline comet assay was employed to evaluate water genotoxicity and DNA damage to lymphocytes in residents living near these waters. A standardized questionnaire was distributed to participants of this study to evaluate their exposure to polluted water. Significant genotoxic activity (p < 0.05) was observed in the lymphocytes of individuals exposed to contaminated water (tail length in Puente Grande 27.88 ± 5.4 compared to 3.77 ± 1.64 of negative control), along with notable DNA damage (p ≤ 0.05) to the lymphocytes of residents living in proximity to these waters (tail length in Juanacatlán 12.3 ± 3.4 compared to 1.4 ± 0.74 of negative control). The waters of the CSB possess the capacity to cause DNA damage; meanwhile, genotoxicity increases from Chapala to El Salto due to the additional input of genotoxic contaminants, thereby elevating the cancer risk for the exposed population. The comet test proved to be a useful tool that allowed data to be obtained quickly and reliably. Full article

Turbidity is a crucial parameter for assessing the ecological health of aquatic ecosystems, particularly in shallow tropical lakes that are subject to climatic variability and anthropogenic pressures. Lake Chapala, the largest freshwater body in Mexico, has experienced persistent turbidity and sediment influx since the 1970s, primarily due to upstream erosion and reduced water inflow. In this study, we utilized Landsat satellite imagery in conjunction with near-synchronous in situ reflectance measurements to monitor spatial and seasonal turbidity patterns between 2023 and 2025. The surface reflectance was radiometrically corrected and validated using spectroradiometer data collected across eight sampling sites in the eastern sector of the lake, the area where the highest rates of horizontal change in turbidity occur. Based on the relationship between near-infrared reflectance and field turbidity, second-order polynomial models were developed for spring, fall, and the composite annual model. The annual model demonstrated acceptable performance (R² = 0.72), effectively capturing the spatial variability and temporal dynamics of the average annual turbidity for the whole lake. Historical turbidity data (2000–2018) and a particular case study in 2016 were used as a reference for statistical validation, confirming the model’s applicability under varying hydrological conditions. Our findings underscore the utility of empirical remote-sensing models, supported by field validation, for cost-effective and scalable turbidity monitoring in dynamic tropical lakes with limited monitoring infrastructure. Full article

The bioaccumulation of heavy metals, such as Cr, Cd, Pb, and As, in vegetables irrigated with contaminated water represents a risk to human health. The objective of this study was to evaluate the Cr concentration in chayote fruits in sites irrigated with contaminated water from Lake Chapala and to assess the potential risk to human health using the estimated daily intake (EDI), objective risk quotient (THQ), and carcinogenic risk quotient (TCR). In parallel, interviews were conducted with local producers to understand their perceptions of the quality of irrigation water and their willingness to adopt more sustainable agricultural practices. In two of the sites and seasons, Cr concentrations exceeded the FAO-WHO limit of 2.3 mg·kg⁻¹ (from 2.49 to 4.82 mg·kg⁻¹). In all, 90% of producers used water from Lake Chapala to irrigate their crops, although most did not perform water quality analyses, despite 32% being aware that the water was contaminated. The results highlight the need to implement strategies to increase awareness of the quality of irrigation water, as well as the need for comprehensive public policies that combine technical assessments and producer perceptions to reduce the risks associated with the use of contaminated irrigation water to promote sustainable agricultural production. Full article

The tropical lake Chapala is an important source of drinking water in western Mexico since it supplies ~65% of the water consumed in the urban city of Guadalajara. To obtain different pollution scenarios, the presence of pollutants in this waterbody was modeled using a coupled hydraulic and transport model. Two water sampling campaigns were modeled. The governing equations were applied using the routines RMA2 and RMA4 in the Surface-Water Modeling System (SMS) software V 8.1. Hydraulic and transport models were calibrated to describe the water level, velocity, and fate of pollutants. The numerical model showed satisfactory results for the simulated data, analyzed against water level, current velocity, and pollutants measurement data through the Relative Percentage Deviation (RPD), except for ~20% of the sites and the 12-month simulation periods. The hydraulic calibrations showed that the dispersion coefficients were higher for nutrients compared to metals, indicating that the nutrients are dispersed throughout the lake and have a stronger impact on the lake’s water quality. The hydraulic model simulations indicated the presence of points in the central-eastern zone, the lowest concentration of ${\mathrm{PO}}_4^{3-}$, which can be attributed to the presence of vortexing. The metal simulations indicated that the dissolved Ni was the best approximation to the measured values. This is the first study on Lake Chapala regarding the modeling fate and transport of pollutants in relation to the prediction of pollution scenarios. Full article

The spread of beta-lactamase-producing bacteria is of great concern and the environment has been found to be a main source of contamination. Herein, it was proposed to determine the frequency of antimicrobial-resistant-Gram-negative bacteria throughout the Lerma River basin using phenotypic and molecular methods. Resistant bacteria were isolated with chromogenic media and antimicrobial susceptibility tests were used to characterize their resistance. ARGs for beta-lactams, aminoglycosides, and quinolones were detected by PCR. Species were identified by Sanger sequencing the 16S rRNA gene and the representative genomes of MDR strains were sequenced by NGS. A high variation in the number of isolates was observed in the 20 sampled sites, while observing a low diversity among the resistant bacteria. Of the 12 identified bacterial groups, C. freundii, E. coli, and S. marcescens were more predominant. A high frequency of resistance to beta-lactams, quinolones, and aminoglycosides was evidenced, where the bla_CTX,qnrB, qnrS y, and aac(6′)lb-cr genes were the most prevalent. C. freundii showed the highest frequency of MDR strains. Whole genome sequencing revealed that S. marcescens and K. pneumoniae showed a high number of shared virulence and antimicrobial resistance genes, while E. coli showed the highest number of unique genes. The contamination of the Lerma River with MDR strains carrying various ARGs should raise awareness among environmental authorities to assess the risks and regulations regarding the optimal hygienic and sanitary conditions for this important river that supports economic activities in the different communities in Mexico. Full article

Lake Chapala is the largest natural freshwater reservoir in Mexico and the third largest lake in Latin America. Lakes are often considered the final deposit of polluting materials; they can be concentrated in the organisms that inhabit them, the water, and the sediments. The PCBs and PBDEs are environmental pollutants highly studied for their known carcinogenic and mutagenic effects. PCB and PBDE bioaccumulation levels were determined in Chirostoma spp., Cyprinus carpio, and Oreochromis aureus. In addition, we monitored the concentrations of PCBs and PBDEs in sediment and water from Lake Chapala were monitored. Samples were collected during two periods, in October 2018 and May 2019. The samples were analyzed by gas chromatography coupled with mass spectrometry. Two bioaccumulation factors were determined in fish, one in relation to the concentration of PCBs and PBDEs in sediments and the other in relation to the concentration of PCBs and PBDEs in water. The PCB levels were 0.55–3.29 ng/g dry weight (dw) in sediments, 1.43–2.98 ng/mL in water, 0.30–5.31 ng/g dw in Chirostoma spp., 1.06–6.07 ng/g dw in Cyprinus carpio, and 0.55–7.20 ng/g dw in Oreochromis aureus. The levels of PBDEs were 0.17–0.35 ng/g dw in sediments, 0.13–0.32 ng/mL in water, 0.01–0.23 ng/g dw in Chirostoma spp., 0–0.31 ng/g dw in Cyprinus carpio, and 0.1–0.22 ng/g dw in Oreochromis aureus. This study provides information for a better understanding of the movement, global distribution, and bioaccumulation of PCBs and PBDEs. The results show that the fish, water, and sediments of Lake Chapala are potential risks to the biota and the local human population. Full article

Aquaculture offers great potential for fish production in Lake Chapala, but reports of heavy metal contamination in fish have identified a main concern for this activity. In the present study, cultures of the species Cyprinus carpio and Ictalurus punctatus were grown in a net cage in Lake Chapala. The patterns of heavy metal accumulation (Cu, Zn, Cd, Hg, Pb, As) in muscle and liver were monitored in order to evaluate the level of metal incorporation in the fish. Estimates of weekly metal intake (EWI) were made based on the results of the concentrations in edible parts of fish of commercial size. The patterns of metal bioaccumulation between tissues and species showed that liver had a higher concentrating capacity for Zn, Cu, Cd, and Pb. In contrast, similar concentrations of Hg and As were found in the liver and muscle tissue. According to the EWI estimates, the heavy metals in these cultured fish do not represent a risk for human consumption. Full article

Background: Access to safe, affordable and accessible drinking water is a human right and foundational to the third and sixth World Health Organization’s Sustainable Development Goals (SDGs). Unsafe drinking water is a risk factor for chronic and enteric diseases. Both chronic kidney disease (CKD) and diarrheal disease are highly prevalent in the Lake Chapala basin, Jalisco, Mexico, suggesting disparities in factors leading to successful achievement of these two SDGs. Methods: This study aimed to assess progress towards SDG three and six in the Lake Chapala basin. Qualitative, quantitative, and geospatial data were collected between May and August of 2019 from three towns within the municipalities of Poncitlán and Chapala. Results: Ninety-nine households participated in this study. Water sampling analyses determined 81.18% of samples from water jugs (garrafones) and 70.05% of samples from tap water were contaminated with total coliform bacteria, often including E. coli. Additionally, 32% of garrafón samples and 61.9% of tap water samples had detectable levels of arsenic. Approximately 97.94% of respondents stated that they believe clean water is a human right, but 78.57% feel the Mexican government does not do enough to make this a reality. Conclusions: This mixed methods approach highlights water quality as a serious issue in communities around Lake Chapala, and demonstrates inadequate drinking water as a key hazard, potentially perpetuating the high disease burden of both CKD and enteric disease in the region. Full article

Temporal delays and spatial randomness between ground-based data and satellite overpass involve important deviations between the empirical model output and real data; these are factors poorly considered in the model calibration. The inorganic matter-generated turbidity in Lake Chapala (Mexico) was taken as a study case to expose the influence of such factors. Ground-based data from this study and historical records were used as references. We take advantage of the at-surface reflectance from Landsat-8, sun-glint corrections, a reduced NIR-band range, and null organic matter incidence in these wavelengths to diminish the physical phenomena-related radiometric artifacts; leaving the spatio-temporal relationships as the principal factor inducing the model uncertainty. Non-linear correlations were assessed to calibrate the best empirical model; none of them presented a strong relationship (<73%), including that based on hourly delays. This last model had the best predictability only for the summer-fall season, explaining 71% of the turbidity variation in 2016, and 59% in 2017, with RMSEs < 24%. The instantaneous turbidity maps depicted the hydrodynamic complexity of the lake, highlighting a strong component of spatial randomness associated with the temporal delays. Reasonably, robust empirical models will be developed if several dates and sampling-sites are synchronized with more satellite overpasses. Full article

The occurrence of Chronic Kidney Disease (CKD) of unknown etiology in autochthonous child populations residing along the Lake Chapala lakeshore is endemic (Jalisco, México). The objective of this study was to determine the prevalence of albuminuria in the pediatric population and to measure the glomerular filtration rate in children with two positive albuminuria tests. Urinary albumin was measured in 394 children. Subjects with two or more positive albuminuria test donated blood samples for the determination of serum biomarkers. From a rural community with 565 children under the age of 17 years, 394 (69.7%) participated with first morning urine samples. A total of 180 children were positive (with two or more positive albuminuria tests). The prevalence of albuminuria among the children participating in the study was 45.7%. Of the 180 children with persistent albuminuria, 160 (88.9%) were tested for serum creatinine, urea, and cystatin C. The 68.1% of the children studied, were found in stages 3a and 3b of the Kidney Disease Improving Global Outcomes (KDIGO) classification (mean glomerular filtration rate (GFR) 51.9 and 38.4 mL/min/1.73 m² respectively). The lowest frequencies were for classifications 1 and 4. None of the subjects was classified as grade 5. The prevalence of albuminuria in children from this rural community is 3–5 times higher than reported in international literature. Regarding GFR, more than 50% of children studied are under 60 mL/min/1.73 m². It is a priority to find the causes of albuminuria and CKD in this Mexican region. Full article

This work assesses the performance of a municipal pilot wastewater treatment system employing an up-flow anaerobic filter (UAF) followed by a horizontal subsurface constructed wetland (HSSCW). This pilot scale demonstration project was implemented in a zone with subtropical climate in order to protect Lake Chapala from wastewater loads that are discharged by small communities in the Lake’s vicinity. The filters were filled with tezontle as the media for biofilm support and the HSSCW was planted with two ornamental plants species, Canna hybrids and Strelitzia reginae. The experiment evaluated three hydraulic retention times (HRT) of 18, 28 and 38 h in the UAF, which corresponds to two, three and four days in HSSCW over 66 weeks. The mean efficiencies found for the complete system were 80% and 90% of BOD, 80% and 86% of COD, 30% and 33% of N_tot and between 24% and 44% of P_tot. It was possible to remove almost 80% of organic matter in 18 h in the UAF while the HSSCW reached 30% of removal for N_tot in a HRT of three days. As expected, the UAF was responsible for removing most of the organic matter and the HSSCW removed most of the nitrogen. Full article