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espanolLas arenas son el segundo recurso natural mas consumido en el planeta despues del agua dulce y superan a los combustibles fosiles y la biomasa. Actualmente se extraen 50 mil millones de toneladas al ano, o un promedio de 18 kg por persona al dia [1]. Aunque el enfoque del ciclo de vida de los materiales requiere que se cuantifiquen los costos ambientales del proceso constructivo en todas sus etapas, los esfuerzos de agencias de la ONU y organismos internacionales por contabilizar las emisiones de CO2 no han considerado la contribucion de los GEI durante el transporte de materiales como la grava y arena y, si lo hacen, los datos estan agregados en otros rubros. Mas del 60% de los agregados petreos producidos en Baja California provienen del cauce del arroyo Las Palmas que corre entre Tijuana y Tecate, B.C.; por lo que los efectos ambientales regionales son importantes. Este estudio tuvo por objetivo estimar las emisiones de CO2 durante el transporte de arena utilizando el metodo de nivel 1 del IPCC y una tecnica de aforo vehicular. Se analizo el acarreo desde la zona de extraccion, en el arroyo Las Palmas, hasta una estacion de transferencia ubicada en el arroyo Alamar. Se identificaron dieciseis tipos de automotores. Para un recorrido de 75 km, se calculo una emision de 77.7 kg de CO2. Se encontraron emisiones desde 0.8 hasta 8.7 kg de CO2 por tonelada de arena transportada; o su volumen equivalente de 1.3 a 13.9 kg/m3; por lo que los automotores mas eficientes en terminos de emisiones fueron los de mayor capacidad de carga, La remocion de arenas de los cauces de rios, ademas de generar impactos hidricos tambien contribuye al cambio climatico debido al impacto acumulativo de las emisiones de CO2, por lo que se enfatiza en la necesidad de politicas para promover medios de transporte mas eficientes para el traslado de materias primas. EnglishThe sands are the second most resources extracted and traded by volume after water and outperform fossil fuels and biomass. Currently, 50 billion tons are extracted per year, or an average of 18 kg per person per day [1]. Although the life cycle approach of materials requires that the environmental costs of the construction process be quantified at all stages, the efforts of UN agencies and international organizations to account for CO2 emissions have not considered the contribution of GHGs during the transport of materials such as gravel and sand and, if they do, the data is aggregated in other topics. More than 60% of the aggregates produced in Baja California come from the Las Palmas river that runs along the municipalities of Tijuana and Tecate, B.C. Hence the regional environmental effects are important. This study aimed to estimate CO2 emissions during sand transport using the IPCC level 1 method and vehicular counting techniques. Sand transportation from the extraction zone, in the Las Palmas river, to a transfer station located in the Alamar river was analyzed. Sixteen types of vehicles were identified. For a route of 75 km, an emission of 77.7 kg of CO2 was calculated. Emissions from 0.8 to 8.7 kg of CO2 were found per ton of sand transported; or its equivalent volume of 1.3 to 13.9 kg / m3; Therefore, the most efficient vehicles in terms of emissions were those with the greatest load capacity. The removal of sands from riverbeds, in addition to generating water impacts, also contributes to climate change due to the cumulative impact of CO2 emissions. This emphasizes the need for policies to promote more efficient means of transport for the transfer of aggregates.

The sands are the second most resources extracted and traded by volume after water and outperform fossil fuels and biomass. Currently, 50 billion tons are extracted per year, or an average of 18 kg per person per day [1]. Although the life cycle approach of materials requires that the environmental costs of the construction process be quantified at all stages, the efforts of UN agencies and international organizations to account for CO2 emissions have not considered the contribution of GHGs during the transport of materials such as gravel and sand and, if they do, the data is aggregated in other topics. More than 60% of the aggregates produced in Baja California come from the Las Palmas river that runs along the municipalities of Tijuana and Tecate, B.C. Hence the regional environmental effects are important. This study aimed to estimate CO2 emissions during sand transport using the IPCC level 1 method and vehicular counting techniques. Sand transportation from the extraction zone, in the Las Palmas river, to a transfer station located in the Alamar river was analyzed. Sixteen types of vehicles were identified. For a route of 75 km, an emission of 77.7 kg of CO2 was calculated. Emissions from 0.8 to 8.7 kg of CO2 were found per ton of sand transported; or its equivalent volume of 1.3 to 13.9 kg / m3; Therefore, the most efficient vehicles in terms of emissions were those with the greatest load capacity. The removal of sands from riverbeds, in addition to generating water impacts, also contributes to climate change due to the cumulative impact of CO2 emissions. This emphasizes the need for policies to promote more efficient means of transport for the transfer of aggregates.

In recent times, electrospun nanofibers have been widely studied from several biotechnological approaches; in this work, poly(acrylic acid) (PAA) solutions mixed with chitosan and alginate were ele...

Land-based sources are considered the most important source of microplastic pollution to marine environment. Stormwater runoff has been identified as one of the main pollutant contributors to water bodies. Seven sites were sampled to identify and quantify microplastics in stormwater runoff in Tijuana, Mexico. The median microplastic abundance found in the samples was between 66 and 191 particles L−1, the highest abundance being recorded in an industrial land use site. The estimated annual total microplastic loads were between 8 × 105 and 3 × 106 particles ha−1. The most abundant microplastic shape and identified polymer type were fibers and polyethylene, respectively. The highest microplastic abundances were observed in events with higher rainfall. The results have shown that stormwater runoff is an important source of microplastic to water bodies.