CEDEUS

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A modeling approach to determining the relationship between vegetative filter strip design and sediment composition
(2017) Lobo, G.; Bonilla Meléndez, Carlos Alberto; CEDEUS (Chile)
A numerical model for linking soil organic matter decay and wildfire severity
(2021) Aedo Quililongo, Sebastián Alejandro; Bonilla Meléndez, Carlos Alberto; CEDEUS (Chile)
Wildfires are a critical phenomenon in terrestrial ecosystems, and the intensity and frequency of these events have increased in recent years. High temperatures in the topsoil during wildfires can induce changes in soil physical, chemical, and biological properties due to the loss of soil organic matter (SOM). Therefore, the main objective of this study was to develop a numerical model to predict SOM decay during wildfire events. The model identifies the main parameters controlling SOM decay and predicts its decline by coupling the energy balance for soil heating and species conservation for water and SOM using high temperature-induced vaporization and combustion kinetics. Fluid flow was not included; however, the radiative energy conducted through soil pores was incorporated as a volumetric pore radius function. When the radiative term in the thermal conductivity was not considered, the model predicted the soil thermal evolution with a determination coefficient r(2) > 0.91 and with an r(2) > 0.98 when the volumetric pore radius was adjusted. The main parameters controlling SOM decay were soil texture, oxygen availability, and initial soil water and SOM contents. SOM decay was also dependent on the wildfire temperature and exposure time. In terms of soil texture, SOM decay increases as sand increases or clay reduces. The main results showed that the soil water content controlled the amount of heat consumed during vaporization, the normalized SOM decay does not depend on the initial SOM content, and the restricted oxidation limited SOM decay. Finally, this study reduces the number of parameters when studying SOM decay and second-order fire effects for post-fire assessment and restoration. Also, because it provides a better understanding of how wildfires affect SOM, implemented as an additional routine, the model can enhance other existing computer models for describing ecological processes.
A preliminary study on aflatoxin exposure by urine biomonitoring in Chile
(2022) Foerster, Claudia; Monsalve, Liliam; Maldonado, Carlos; Cortés Arancibia, Sandra; Ferreccio, Catterina; CEDEUS (Chile)
We assessed the occurrence of aflatoxin M1 (AFM1) in urine in a sample of the MAUCO population-based cohort (n = 120) using an enzyme-linked immune sorbent assay (ELISA) kit specially designed for the analysis of AFM1 in urine. We found AFM1 in the urine of 59% of the participants (> limit of detection), with 12% of the samples being over the limit of quantification. The mean of the quantifiable samples was 0.66 (± 0.35) ng/mg adjusted creatinine, ranging from 0.31 to 1.39 ng/mg creatinine. The mean probable daily intake (PDI) of AFB1 was 0.23 (± 0.37) ng/kg bw according to the upper bound (UB), being significantly higher in women and 0.14 (± 0.23) ng/kg bw in the modified lower bound (mLB) approach, ranging from 0.01 to 1.98 ng/kg bw. The risk of AFB1 was assessed with the margin of exposure (MOE) approach estimated at 2800 in the mean mLB and 1733 in the mean UB. According to the MOE values obtained in this study, aflatoxin B1 exposure must be considered a public health concern and must be taken as a priority for food risk management.
Air pollution and environmental epidemiological evidence in Chile: alerts for decision-makers and citizens
(2023) Cortés Arancibia, Sandra; CEDEUS (Chile)
Air pollution in Chile presents unique challenges, exacerbated by inequalities and geographical and climatic diversity. Current policies have not succeeded in aligning air quality with international and national standards, nor have they significantly mitigated public health impacts, despite being more advanced than those in other Latin American countries. The evidence on the health damages caused by air pollution is compelling, showing harmful acute and chronic effects across various life stages. Yet, current measures do not effectively reduce exposure to pollutants. The monitoring network, which reports data from stationary and mobile sources, does not always detect early fugitive emissions and is limited to regulated pollutants, leaving areas without adequate monitoring coverage and without management plans for critical episodes outside of autumn and winter and for a reduced number of pollutants. In the context of climate change, which increases the frequency of forest fires, Chile is experiencing a deterioration of air quality, highlighting the need to expand critical episode management beyond the current Air Pollution Prevention and/or Atmospheric Decontamination Plans. Integrated intersectoral plans need to be improved and extended to address the high exposure to pollutants, due to the large number of people exposed, and a broad population health risks, including quality of life. Decarbonisation by 2040 based on the Sustainable Development Goals is an important pillar of the strategy, but a public debate is needed to establish additional actions for addressing environmental injustice, improving equity and reducing current exposure to air pollutants.
Barreras estructurales en la caminabilidad y accesibilidad a escala de barrio. Estudio de tres casos en Santiago de Chile
(2020) Berrios Álvarez, Emilio Moisés; Greene, Margarita; CEDEUS (Chile)
Dada la relevancia de la accesibilidad a bienes y servicios urbanos en la calidad de vida de los habitantes, y considerando que la caminata representa el principal modo de transporte en el Gran Santiago -34,6% de los viajes, según la Encuesta de Origen y Destino de 2012 (Universidad Alberto Hurtado, 2014)-, la presente investigación tiene como objetivo analizar y comparar las barreras estructurales que inciden en el área caminable a escala de barrio y estimar sus posibles efectos en los patrones de movilidad y acceso a bienes y servicios, en tres conjuntos habitacionales del Gran Santiago: población Juan Antonio Ríos sector 3B (Independencia), villa San Cristóbal (Recoleta) y villa Los Sauces (La Florida). Para cada caso, se identificaron las principales barreras materiales, ya sean naturales (ríos, cerros) o artificiales (carreteras, pasos bajo/sobre nivel) y algunas barreras intangibles (asociadas a la seguridad vial o delictual). Se comparó la superficie teórica máxima del barrio caminable (euclidiana) con la “real” calculada mediante análisis de red (sobre la base de recorridos de 20 min), considerando las condiciones de cruce de las principales vías, cuantificando sus efectos en tiempo y distancia y la consiguiente accesibilidad a equipamiento y servicios. Además, se analizó la configuración de la trama vial y peatonal, contrastando su integración a escala local y global basada en mapas axiales. Finalmente, se analizaron los patrones de movilidad de la población según datos de zona EOD 2012. Los resultados muestran una clara disminución del área real del barrio caminable (a un tercio del área euclidiana), producto de la trama y de las diversas barreras existentes, lo que se refleja en la accesibilidad a bienes y servicios vía caminata. Estos resultados permiten proponer además que, si bien una mayor distancia promedio de caminata no se relaciona con una mayor área caminable, la cercanía a centralidades sí se asocia con la prevalencia de este modo de transporte.
Combining Cluster Analysis of Air Pollution and Meteorological Data with Receptor Model Results for Ambient PM2.5 and PM10
(2020) Jorquera, Héctor; Villalobos, Ana María; CEDEUS (Chile)
Air pollution regulation requires knowing major sources on any given zone, setting specific controls, and assessing how health risks evolve in response to those controls. Receptor models (RM) can identify major sources: transport, industry, residential, etc. However, RM results are typically available for short term periods, and there is a paucity of RM results for developing countries. We propose to combine a cluster analysis (CA) of air pollution and meteorological measurements with a short-term RM analysis to estimate a long-term, hourly source apportionment of ambient PM2.5 and PM10. We have developed a proof of the concept for this proposed methodology in three case studies: a large metropolitan zone, a city with dominant residential wood burning (RWB) emissions, and a city in the middle of a desert region. We have found it feasible to identify the major sources in the CA results and obtain hourly time series of their contributions, effectively extending short-term RM results to the whole ambient monitoring period. This methodology adds value to existing ambient data. The hourly time series results would allow researchers to apportion health benefits associated with specific air pollution regulations, estimate source-specific trends, improve emission inventories, and conduct environmental justice studies, among several potential applications.
Effect of temporal resolution on rainfall erosivity estimates in zones of precipitation caused by frontal systems
(2015) Lobo, Gabriel P.; Bonilla Meléndez, Carlos Alberto; CEDEUS (Chile)
Effects of biodiversity in green roofs and walls on the capture of fine particulate matter
(2021) Vera Araya, Sergio Eduardo; Viecco Márquez, Margareth Indira; Jorquera, Héctor; CEDEUS (Chile)
Exposure to ambient PM2.5 poses serious threats to human health. In such cases, the presence of green roofs (GRs) and green walls (GWs) has several environmental benefits, including the capture of pollutants. Choosing appropriate designs of GWs and GRs to improve urban air quality is challenging because their performances depend on their constituent species and environmental characteristics of the particular locality. Capture of PM2.5 by different plant species of GRs and GWs has been measured only on monocultures. The impact of planting different species together (polycultures) on capturing PM2.5 remains unexplored. This paper aims to evaluate the impact of biodiverse GRs and GWs on PM2.5 capture. Seven species were analyzed as polycultures: Sedum album, Lampranthus spectabillis, Sedum spurium P, Lavandula angustifolia, Erigeron karvinskianus, Aptenia cordifolia, and Sedum palmeri. PM2.5 capture was measured by two methods: gravimetric determination and decay curve. Gravimetric results suggest that higher the biodiversity of plants in GRs and GWs, higher the PM2.5 capture, particularly for species with relatively low capture when used as monocultures. The ability to capture PM2.5 is dependent on the plant species, relative position of plants within the polyculture, and horizontal (GRs) or vertical (GWs) layout. Decay method results suggest that polycultures could be more effective in long-term reduction of high PM2.5 concentrations.
Estimation of crowding factors for public transport during the COVID-19 pandemic in Santiago, Chile
(2022) Basnak Klajn, Paul Alexander; Giesen Encina, Ricardo; Muñoz Abogabir, Juan Carlos; CEDEUS (Chile)
A sharp decrease in public transport demand has been observed during the COVID-19 pandemic around the world. In this context, it is relevant to understand how mode preferences have changed since the surge of COVID-19.& nbsp;In order to better understand how the pandemic changed mode choice, particularly regarding the impact of crowding and face mask use in public transport, we conducted a stated preference on-line and on-street survey in Santiago, Chile. Our sample is balanced in gender but has a higher proportion of individuals with college degrees and those under 45 years of age than the population of Santiago.& nbsp;The data collected was then used to estimate two multinomial mode choice models, a latent class model and a mixed logit model with latent variables.& nbsp;The models yielded a value of travel time in crowded conditions (4 pax/m2) and low face mask use (50%) of 3.0-5.1 times higher than the case with low crowding (0.5 pax/m2) and 100% face mask use. Moreover, women tend to be more sensitive than men to the use of face masks in public transport. Besides, young and low-income people are relatively less sensitive to crowding.& nbsp;The crowding penalization obtained is higher than in pre-pandemic models calibrated for Santiago for similar passenger densities. Also, as we expected, it grows non-linearly with passenger density. Disinfection of vehicles, as well as the perception of health risk, cleanliness, safety and comfort, were also relevant in explaining mode choice. Further research shall discuss how the change of mode preferences together with new demand patterns influence the operational design of public transport services.
Evaluation and improvement of the CLIGEN model for storm and rainfall erosivity generation in Central Chile
(2015) Lobo, Gabriel P.; Bonilla Meléndez, Carlos Alberto; Frankenberger, James R.; Flanagan, Dennis C.; CEDEUS (Chile)
Local and NON-LOCAL source apportionment of black carbon and combustion generated PM2.5
(Elsevier Ltd, 2024) Rodríguez Rangel, Jessika Carolina; Villalobos, Ana María; Castro-Molinare J.; Jorquera González, Héctor Iván Joaquin; CEDEUS (Chile)
Current methods for measuring black carbon aerosol (BC) by optical methods apportion BC to fossil fuel and wood combustion. However, these results are aggregated: local and non-local combustion sources are lumped together. The spatial apportioning of carbonaceous aerosol sources is challenging in remote or suburban areas because non-local sources may be significant. Air quality modeling would require highly accurate emission inventories and unbiased dispersion models to quantify such apportionment. We propose FUSTA (FUzzy SpatioTemporal Apportionment) methodology for analyzing aethalometer results for equivalent black carbon coming from fossil fuel (eBCff) and wood combustion (eBCwb). We applied this methodology to ambient measurements at three suburban sites around Santiago, Chile, in the winter season 2021. FUSTA results showed that local sources contributed ∼80% to eBCff and eBCwb in all sites. By using PM2.5 – eBCff and PM2.5 – eBCwb scatterplots for each fuzzy cluster (or source) found by FUSTA, the estimated lower edge lines showed distinctive slopes in each measurement site. These slopes were larger for non-local sources (aged aerosols) than for local ones (fresh emissions) and were used to apportion combustion PM2.5 in each site. In sites Colina, Melipilla and San Jose de Maipo, fossil fuel combustion contributions to PM2.5 were 26 % (15.9 μg m−3), 22 % (9.9 μg m−3), and 22 % (7.8 μg m−3), respectively. Wood burning contributions to PM2.5 were 22 % (13.4 μg m−3), 19 % (8.9 μg m−3) and 22% (7.3 μg m−3), respectively. This methodology generates a joint source apportionment of eBC and PM2.5, which is consistent with available chemical speciation data for PM2.5 in Santiago.
Local and regional sources of organochlorine pesticides in a rural zone in central Chile
(2022) Llanos Castillo, Yasna Jovita; Cortés Arancibia, Sandra; Martínez, Andrés; Pozo, Karla; Přibylová, Petra; Klánová, Jana; Jorquera, Héctor; Cortés Arancibia, Sandra; Hurtado-Epstein, Andrea; Buss, Daniel F.; Hartinger, Stella M.; CEDEUS (Chile)
There is a lack of knowledge about exposure to airborne organochlorinated pesticides (OCPs), especially for people living near agricultural zones in developing countries. This study is the first one to measure spatiotemporal variation of airborne OCPs within a major agriculture area in Central Chile. Polyurethane foam passive air samplers (PUF-PAS) were deployed in five sites in the town of Molina (35°7′S, 71°17′W) and another one in the nearby town of Lontué (35°3′S, 71°17′W). Samplers were deployed from August 2016 to January 2018, in 8 periods lasting 2–3 months each. The measured concentrations in air (pg m−3) as geometric mean were α-HCH: 0.59, γ-HCH: 3.8, o,p'-DDT: 1.3, p,p'-DDT: 2.0, o,p'-DDE: 0.52, p,p'-DDE: 5.5, o,p'-DDD: 0.26, p,p'-DDD: 0.64, PeCB: 29.1 and HCB: 14.5. The highest concentrations were measured in the warmer months and negative correlations (p < 0.05) between the log of the concentrations and the inverse of ambient temperature were found, suggesting soil volatilization as the main release process. The exceptions were o,p'-DDE, p,p'-DDE and HCB. In the case of HCB, waste burning was a likely source. Most OCP concentrations showed significant spatial heterogeneity (p < 0.05), suggesting local source contributions are dominant; the exceptions are α-HCH and PeCB (p > 0.05) whose concentrations depend on regional sources. Backward wind trajectories obtained using NOAA's HYSPLIT identified air masses coming from the south and southwest when ambient concentrations are highest; these regional sources contribute to all ambient OCP concentrations.
Machine learning for policing: a case study on arrests in Chile
(2020) Wout, Elwin van't; Pieringer Baeza, Christian Philip; Torres Irribarra, David; Asahi Kodama, Kenzo Javier; Larroulet Philippi, Pilar; CEDEUS (Chile)
Police agencies expend considerable effort to anticipate future incidences of criminal behaviour. Since a large proportion of crimes are committed by a small group of individuals, preventive measures are often targeted on prolific offenders. There is a long-standing expectation that new technologies can improve the accurate identification of crime patterns. Here, we explore big data technology and design a machine learning algorithm for forecasting repeated arrests. The forecasts are based on administrative data provided by the national Chilean police agencies, including a history of arrests in Santiago de Chile and personal metadata such as gender and age. Excellent algorithmic performance was achieved with various supervised machine learning techniques. Still, there are many challenges regarding the design of the mathematical model, and its eventual incorporation into predictive policing will depend upon better insights into the effectiveness and ethics of preemptive strategies.
Pesticide exposure in Chile and population health: urgency for decision making [Exposición a plaguicidas en Chile y salud poblacional: urgencia para la toma de decisiones]
(2020) Zúñiga-Venegas, Liliana; Pancetti, Floria; Muñoz-Quezada, María Teresa; Lucero, Boris; Foerster, Claudia; Cortés Arancibia, Sandra Isabel; Saracini, Chiara; CEDEUS (Chile)
In the last 25 years, Chile has had an expanding role as an agro-export country in the global economy, with efficient rates of productivity in the region, based on the technological development of agriculture, with of large monocultures whose productivity depends on the intensive application of agrochemicals. This form of agriculture has also lacked efficient regulations and surveillance, so it is difficult to estimate the real magnitude of the exposed population and its effects on health in the short or long term. This systema-tic review compiles the epidemiological evidence generated from studies conducted in several regions of Chile regarding pesticide exposure and health effects. Of the total number of articles, 50% included agricultural workers, 25% children, and 25% women of childbearing age, with the greatest effects being the neurotoxic (54%), genotoxic (31%) and reproductive (15%). The evidence collected shows that in Chile the levels of exposure to pesticides in the general and occupational population are higher than interna-tional studies levels. It is urgent to protect the health of both the occupational and general population and especially children through a stricter control of the sale and use of pesticides, with comprehensive surveillance systems in environmental health and educational actions in the social and cultural context of rural communities. It is a priority to strengthen research with national relevance on health effects, and strictly restrict the use of pesticides already prohibited in developed countries due to their high level of risk to human and environmental health. (c) 2020 SESPAS. Published by Elsevier Espana, S.L.U. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Predictive modeling the effect of Local Climate Zones (LCZ) on the urban meteorology in a tropical andean area
(Springer Heidelberg, 2024) Mancheno Dominguez, Gabriela Alejandra; Castro Molinare, Julio Enrique; Jorquera, Héctor; CEDEUS (Chile)
The Weather Research & Forecasting Model (WRF, Version 4.4) was applied to simulate meteorological conditions in the city of Quito, Ecuador, located in a tropical Andean landscape. These simulations included the urban canopy into WRF, using the Building Environment Parameterization (BEP) scheme combined with Local Climate Zones (LCZ) land use classification; the innermost domain had a horizontal resolution of 2 km. The simulation results showed that using LCZ + BEP options improved the representation of wind speed and planetary boundary layer height (PBLH), in comparison with WRF counter fact simulations which did not use BEP. For temperature and relative humidity, implementation of LCZ did not improve WRF simulations with respect to those counter fact simulations. This may be ascribed to the use of the default LCZ thermophysical parameters, suggesting the need for gathering local built environment features. The best WRF configuration found for wind speed was the one that combined BEP scheme, LCZ land use and the Yonsei University (YSU) PBL model with topographic option activated; this happened for dry and wet seasons and for the unique meteorological conditions in December. Regarding PBLH modeling, the best configurations were YSU-BEP-LCZ (December), MYJ-BEP-LCZ (April, wet season) and YSU (August, dry season). The findings showed the major influence of urban canopy - described by LCZ - on wind circulation and PBLH simulated within the city at high horizontal resolution (2 km). This effect should be considered when modeling atmospheric pollutant dispersion, choosing urban development strategies, and analyzing prospective climate change scenarios, among other goals.
Testing the integral suspension pressure method for soil particle size analysis across a range of soil organic matter contents
(2021) Acevedo Godoy, Sara Ester; Contreras Torres, Cristina Pamela; Ávila Gorostiaga, Carlos Javier; Bonilla Meléndez, Carlos Alberto; CEDEUS (Chile)
Particle-size distribution is a critical part of soil description, which is commonly measured using pipette and hydrometer methods. However, a recently developed technique, called the integral suspension pressure method, allows for the measurement of continuous particle-size distribution based on Stokes' law. The objective of this study was to evaluate the applicability of the integral suspension pressure method for measuring particle-size distribution, as an alternative to the standard hydrometer procedure. The integral suspension pressure method was tested by using a soil dataset with a wide range of organic matter contents (0.22-12.0%). Forty-nine samples were analysed with a hydrometer after organic matter removal and the results were compared with those obtained using the integral suspension pressure method. Through comparing the integral suspension pressure and hydrometer measurements, root mean square error values of 8.9, 8.1, and 11.9% were observed for sand, silt, and clay, respectively. The clay fraction was underestimated throughout the entire range of measurements. Conversely, the silt content was overestimated over the whole range of measurements, especially in samples with more than 36% silt. When compared to the hydrometer method, integral suspension pressure integral suspension pressure exhibited a tendency to misclassify the soil texture of clay loam samples but was accurate for sandy loams.
While clearing the forests: The social–ecological memory of trees in the Anthropocene
(2024) Ibarra Eliessetch, José Tomás; Riquelme Maulén, Wladimir Esteban; Bañales Seguel, Camila; Orrego, Gabriel; Salazar Preece, Gonzalo; CEDEUS (Chile)
The Anthropocene concept raises awareness of human-induced planetary changes but is criticized for being ‘too global’. We examined the social–ecological memory that emerges from people-tree relationships in South American temperate territories, Chile. We integrated dendrochronology (analysis of tree rings of 35 memorial trees; 17 species) with dendrography (participant observation complemented with semi-structured and goalong interviews with 14 interviewees; six women, eight men). We found that assemblages of people–tree relationships reflect marked historical changes in the territory, associated with the historical clearing of forests, which may be imprinted in both tree growth rings and in the social meanings and practices associated with memorial trees. In devastated territories, practices of tree care emphasize interconnectedness, multispecies collaborations, and the blurring of boundaries between humans and otherthan-humans. We discuss some of the interdisciplinary and relational insights of our study, which may prove valuable for future research, political agendas, and educational programs in South America and beyond.
Wood burning pollution in Chile: A tale of two mid-size cities
(2021) Jorquera, Héctor; Villalobos, Ana María; Schauer, James J.; CEDEUS (Chile)
Cities in southern Chile are facing high levels of PM2.5 because of wood burning pollution. We quantify the contribution of wood smoke to fine particles in two mid-size cities: Molina and Valdivia, located in different climate zones. The sampling campaigns were carried out during austral winter (July to September) in 2018 (Molina) and 2019 (Valdivia). 24-h filter samples were analyzed for carbonaceous compounds, secondary ions, metals, and particle-phase organic molecular markers. Average winter concentrations of PM2.5 were 53 ± 32 μg/m3 (average ± standard deviation) in Molina and 89 ± 55 μg/m3 in Valdivia. The major component of fine particles was organic matter, representing more than 70% of PM2.5. Concentrations of organic molecular markers were used in a receptor model (US EPA CMB8.2) to identify and quantify primary sources of PM2.5. The major source of PM2.5 was wood smoke, which accounted for 41.55 ± 9.77 μg/m3 (62.9 ± 15.3%) in Molina and 43.65 ± 24.06 μg/m3 (51.7 ± 21.1%) in Valdivia. Secondary organic aerosols (SOA) generated from inefficient wood burning, contributed 20.4 ± 17.7% in Molina and 28.9 ± 27.6% in Valdivia. Secondary inorganic ions and dust are minor sources of PM2.5. The total contribution of wood smoke (adding primary wood smoke and SOA) could be as much as 83% in Molina and 81% in Valdivia, during the winter season.

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