Browsing by Author "Pasten Gonzalez, Pablo Arturo"

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    A comparative study of soil metal concentrations in Chilean urban parks using four pollution indexes
    (2022) Vega, Alejandra; Arce, Guillermo; Rivera, Javier I.; Acevedo, Sara E.; Reyes Paecke, Sonia; Bonilla, Carlos A.; Pasten Gonzalez, Pablo Arturo; CEDEUS (Chile)
    Toxic metal enrichment in urban soils from natural and anthropogenic sources is a public health concern thatchallenges sustainable urban development. Active and legacy mining is likely a major contributor of localizedmetal pollution in resource-based economies, although other sources associated with industrial and trans-portation activities may also contribute in urban settings. In mining countries, such as Chile, with no soil qualityregulation, public policies that seek to protect human health should assess metal distribution and pollution in-dexes to guide interventions, especially in urban green spaces. To assess the role of active and legacy miningwaste sites within the urban and peri-urban areas, metal concentrations in the soils of urban parks weremeasured in this study, and four pollution indexes were calculated for four cities of Chile. Copiap ́o and Andacolloin northern Chile represented the cities with several active and legacy mining waste sites located within theurban and peri-urban areas, while conurbation La Serena-Coquimbo and Gran Santiago represented the cities inmining districts that lacked major mining waste sites within their urban perimeters. A total of 82 (Copiap ́o), 30(Andacollo), 26 (La Serena-Coquimbo), and 59 (Gran Santiago) composite surface soil samples were collectedfrom the urban parks. Considering Canadian guidelines for residential/parkland soils, the value for Cu (63 mg/kg) was found to be exceeded in 99%, 50%, 100%, and 97% of samples collected from Copiap ́o, La Serena-Coquimbo, Andacollo, and Gran Santiago, respectively. The guidelines for lead (140 mg/kg) and zinc (250mg/kg) were exceeded in less than 12% of samples collected from Copiap ́o and Gran Santiago. Arsenic was notmainly quantified (<10% quantification frequency, quantification limit = 36 mg/kg). The calculated modifiedpollution load, Nemerow, and soil quality indexes indicated that soils in the urban parks were more polluted incities with urban mine wastes, however, the pollution load index ranked higher metal pollution in Gran Santiago.This study presented the first comparative study of metals in urban parks of Chile, highlighting a large proportionof parks with soil copper concentrations above the international guidelines, while showing higher median values in cities containing urban mine waste disposal sites.
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    A simple low-cost approach for transport parameter determination in mountain rivers
    (2021) Castillo, Daniela; Runkel, Robert L.; Duhalde, Denisse; Pasten Gonzalez, Pablo Arturo; Arumí, José L.; Oyarzún, Jorge; Núñez, Jorge; Maturana, Hugo; Oyarzún, Ricardo; CEDEUS (Chile)
    A simplified low-cost approach to experimentally determine transport parameters inmountain rivers is described,with an emphasis on the longitudinal dispersion coefficient(DL). The approach is based on a slug injectionof table salt (NaCl) as a tracer and specificconductance readings at different locations downstream of the injection spot. Observedspecific conductance readings are fit using the advection-dispersion equation withOTIS-P, yielding estimates of cross-sectional area and longitudinal dispersion coefficientfor various stream reaches. Estimates of theDLare used to assess the accuracy of sev-eral empirical equations reported in the literature. This allowed the determination ofcomplementary transport parameters related to transient storage zones. The empiricalequations yielded rather highDLvalues, with some reaching up an order of magnitudehigher to those obtained from tracer additions and OTIS-P. Overall, the proposedapproach seems reliable and pertinent for river reaches of ca. 150 m in length.
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    Arsenic removal by in-situ formation of iron and sulfur minerals
    (2014) Vega, A.S.; Leiva, E.A.; Pizarro, G.E.; Pasten Gonzalez, Pablo Arturo
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    Arsenic Speciation in Solid Phases of Geothermal Fields
    (2008) Pasten Gonzalez, Pablo Arturo
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    Assessment of a conservative mixing model for the evaluation of constituent behavior below river confluences, Elqui River Basin, Chile
    (2021) Rossi, Catalina; Oyarzún, Jorge; Pasten Gonzalez, Pablo Arturo; Runkel, Robert L.; Núñez, Jorge; Duhalde, Denisse; Maturana, Hugo; Rojas, Eduardo; Arumí, José L.; Castillo, Daniela; Oyarzún, Ricardo
    The use of copper tailings as supplementary cementitious material can reduce the environmental impacts ofconcrete production and the mining industry. A key concern limiting its application is the potential leaching oftoxic metals from the cementitious matrix, especially copper. To analyze and reduce the risk of leaching, themechanisms by which copper is entrapped in the cementitious matrix were investigated, by combining micro-scopic and spectroscopic approaches. Decreasing the water-to-binder ratio was statistically relevant to reducecopper leaching. Scanning Electron Microscope micrographs allowed to spatially localize enriched copperclusters within the cementitious hydration products. In the early stages of the cementitious hydration (i.e., 24 h),no spatial correlation between copper and hydration products was found; however, after seven days, copper wasspatially associated with calcium silicate hydrates. Cu K-edge X-ray absorption near edge structure spectroscopyprovided insights into the chemical speciation of copper in the cementitious matrix. It showed that copper sulfideand oxide phases persisted, whereas the copper sulfate phases were prone to dissolution and reprecipitation ascupric hydroxides induced by the relatively high pH from calcium hydroxides formed during hydration. Pro-moting the formation of hydration products can further reduce copper leaching from the alkaline cementitiousmatrix. A better understanding of metal entrapment mechanisms could lead to new strategies that reduce themobility of toxic elements when using copper tailings, increasing their use as a replacement of cement. With thisknowledge, it is expected to answer if it is possible to improve the copper entrapment into the cementitiousmatrix and if there is a risk of leaching once is entrapped.
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    Biogeochemical controls on arsenic: El Tatio Geyser Field, Chile
    (2007) Landrum, J.T.; Bennett, P.C.; Alsina, M.A.; Pasten Gonzalez, Pablo Arturo
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    Cell-free biosensors for rapid detection of water contaminants
    (2020) Pasten Gonzalez, Pablo Arturo
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    Challenges and opportunities for drinking water treatment residuals (DWTRs) in metal-rich areas: an integrated approach
    (2022) Briso, Alejandro; Vega, Alejandra; Molinos Senante, María; Pasten Gonzalez, Pablo Arturo; CEDEUS (Chile)
    The physicochemistry and production rate of drinking water treatment residuals (DWTRs) depends on the raw water composition and the plant operational parameters. DWTRs usually contain Fe and/or Al oxyhydroxides, sand, clay, organic matter, and other compounds such as metal(oids), which are relevant in mining countries. This work proposes a simple approach to identify DWTRs reuse opportunities and threats, relevant for public policies in countries with diverse geochemical conditions. Raw water pollution indexes and compositions of DWTRs were estimated for Chile as a model case. About 23% of the raw drinking water sources had moderate or seriously contamination from high turbidity and metal(loid) pollution If the untapped reactivity of clean DWRTs was used to treat resources water in the same water company, the 73 and 64% of these companies would be able to treat water sources with As and Cu above the drinking water regulations, respectively. Integrating plant operational data and the hydrochemical characteristics of raw waters allows the prediction of DWTRs production, chemical composition, and reactivity, which is necessary to identify challenges and opportunities for DWTRs management.
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    Chemical functionalization of drinking water treatment residuals with calcium silicate hydrate to treat metal-enriched waters
    (2023) Alejandro Briso; Ana Turri-Rivero; Mauricio Montecinos; María Molinos-Senante; Pasten Gonzalez, Pablo Arturo; CEDEUS (Chile)
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    Chemical-hydrodynamic control of arsenic mobility at a river confluence
    (2014) Guerra, P.A.; Gonzalez, C.; Escauriaza, C.E.; Bonilla, C.A.; Pasten Gonzalez, Pablo Arturo; Pizarro, G.E.
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    Chilean water resources
    (2007) Muñoz, J.F.; Fernández, B.; Varas, E.; Pasten Gonzalez, Pablo Arturo; Gómez, D.; Rengifo, P.; Muñoz, J.; Atenas, M.; Jofré, J.C.
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    Copper entrapment and immobilization during cement hydration in concrete mixtures containing copper tailings
    (2021) Vargas, Felipe; Alsina, Marco A.; Gaillard, Jean-François; Pasten Gonzalez, Pablo Arturo; López, Mauricio; CEDEUS (Chile)
    The use of copper tailings as supplementary cementitious material can reduce the environmental impacts ofconcrete production and the mining industry. A key concern limiting its application is the potential leaching oftoxic metals from the cementitious matrix, especially copper. To analyze and reduce the risk of leaching, themechanisms by which copper is entrapped in the cementitious matrix were investigated, by combining micro-scopic and spectroscopic approaches. Decreasing the water-to-binder ratio was statistically relevant to reducecopper leaching. Scanning Electron Microscope micrographs allowed to spatially localize enriched copperclusters within the cementitious hydration products. In the early stages of the cementitious hydration (i.e., 24 h),no spatial correlation between copper and hydration products was found; however, after seven days, copper wasspatially associated with calcium silicate hydrates. Cu K-edge X-ray absorption near edge structure spectroscopyprovided insights into the chemical speciation of copper in the cementitious matrix. It showed that copper sulfideand oxide phases persisted, whereas the copper sulfate phases were prone to dissolution and reprecipitation ascupric hydroxides induced by the relatively high pH from calcium hydroxides formed during hydration. Pro-moting the formation of hydration products can further reduce copper leaching from the alkaline cementitiousmatrix. A better understanding of metal entrapment mechanisms could lead to new strategies that reduce themobility of toxic elements when using copper tailings, increasing their use as a replacement of cement. With thisknowledge, it is expected to answer if it is possible to improve the copper entrapment into the cementitiousmatrix and if there is a risk of leaching once is entrapped.
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    Elemental sulfur (SO) as a supplemental electron donor for wastewater denitrification: Batch and column studies
    (2012) Wang, Y.; Pasten Gonzalez, Pablo Arturo; Bott, C.; Nerenberg, R.
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    Environmental Aspects of a Major ARD Source at El Indio Au-Cu-As District, North-Central Chile
    (2022) Oyarzún, Jorge; Maturana, Hugo; Paulo, Andrzej; Lillo, Javier; Pasten Gonzalez, Pablo Arturo; Núñez, Jorge; Duhalde, Denisse; González, Cinthya; Portilla, Adriana; Oyarzún, Ricardo
    El Indio, an Au-Cu-As deposit with outstanding gold grades, was mined in the Andes of the Coquimbo region, Chile, between 1975 and 2002. Sediment and water sampling of the rivers in the 2000 s found exceptional As and metal levels in modern and old sediments. The studies also revealed that acid rock drainage (ARD) has been present in the district for nearly 10,000 years and the effect that the mining of the district had in terms of geochemical anomalies. The convergence of mineralogical, structural, and hydrologic conditions has generated a metal-rich ARD, a process followed by transference of metals to the f ine sediments. In this context, the study also deals with the risk of metal and metalloid transfers from the sediments to the river waters as a consequence of eventual physical-chemical changes, due for example, to climatic-driven conditions. Water and sediment samplings were carried out to provide materials for selective extraction tests under acidic, acid-reducing, and acid-oxidizing conditions. The different behavior of metals and metalloids was revealed and highlighted the refractory character of As. Additionally, the study included the characterization of the sediment’s mineralogy, and allowed the detection of new geochemical anomalies of Cu, Zn, Co, and Y in the Incaguaz River, along with high dissolved Li concentrations in the Toro and Turbio rivers..
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    Erratum: Towards a benchmarking model for winery wastewater treatment and disposal (Water Science and Technology vol. 56 (2) (153-160))
    (2007) Aybar, M.; Carvallo, M.; Fabacher, F.; Pizarro, G.; Pasten Gonzalez, Pablo Arturo
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