No abstract

As society evolves its welfare level increases, and as a consequence the amount of municipal solid waste increases, imposing great challenges to municipal authorities. In developed countries, municipalities have established integrated management schemes to handle, treat, and dispose of municipal solid waste in an economical and environmentally sound manner. Municipalities of developing and transition countries are not exempted from the challenges involving municipal solid waste handling, but their task is not easy to accomplish since they face budget deficits, lack of knowledge, and deficiencies in infrastructure and equipment. In the northern territory of Mexico, the municipality of Durango is facing the challenge of increased volumes of waste with a lack of adequate facilities and infrastructure. This article analyses the evolution of the municipal solid waste management of Durango city, which includes actions such as proper facilities construction, equipment acquisition, and the implementation of social programmes. The World Bank, offering courses to municipal managers on landfill operation and waste management, promoted the process of knowledge and technology transfer. Thereafter, municipal authorities attended regional and some international workshops on waste management. In addition they followed suggestions of international contractors and equipment dealers with the intention to improve the situation of the waste management of the city. After a 15-year period, transfer of knowledge and technology resulted in a modern municipal solid waste management system in Durango municipality. The actual system did not reach the standard levels of an integrated waste management system, nevertheless, a functional evaluation shows clear indications that municipality actions have put them on the right pathway.

Cedrela odorata L., conocida como cedro rojo, es una de las especies de mayor valor económico en la producción forestal de México. Aunque la madera es el producto principal que se obtiene de esta especie, se generan también residuos como ramas y hojas en los aclareos y podas, así como aserrín y costeras en el aserrío. En este trabajo se evaluó la composición química de hojas, madera de ramas y aserrín de cedro rojo, en muestras colectadas en dos plantaciones experimentales en El Palmar, Veracruz y San Felipe Bacalar, Quintana Roo, así como la concentración de fenoles totales, flavonoides y su capacidad de captación de radicales libres, enfocadas hacia valorar su potencial como fuente lignocelulósica para obtención de biocombustibles y/o hacia la aplicación en áreas biomédicas. Las hojas presentan altas concentraciones de extraíbles con valores máximos de 34,78%, polisacáridos 67,11%, lignina 33,10%, azúcares reductores 6,52%, fenoles 211,91 mgEAG/g, flavonoides 81,05 mgEC/g, pero no presentan actividad de antiradicales libres. En cambio, la madera, tanto de ramas como de aserrín, presenta bajas concentraciones de extraíbles 6,10%, polisacáridos 78,46%, lignina 32,24%, azúcares reductores 8,87%, fenoles 355,57 mgEAG/g, flavonoides 178,56mgEC/g, y alta capacidad de captación de radicales libres. Se encontraron diferencias en las concentraciones lignocelulósicas entre las muestras colectadas en las dos plantaciones, sobresaliendo las colectadas en Bacalar, Q. R. Los resultados obtenidos indican que las hojas, la madera de ramas y aserrín son viables para obtención de carbohidratos, mientras que la madera puede ser una fuente de obtención fenoles y flavonoides con posibles aplicaciones terapéuticas.

Fluorine (F) and arsenic (As) are inorganic elements present in the subsurface depending on the geology of the region. These compounds are found in high concentrations in the underground strata of Guadiana Valley of Durango affecting water quality for human consumption (NOM-127-SSA-1994). In the present research the main objective was to assess the behavior in time and space of fluoride (F −) and arsenic concentration, from 1996 to date, in the groundwater of the city of Durango and some wells of the rural area as a reference. The highest concentration of arsenic was found in a rural well, Colonia Hidalgo (0.149 mg/L or ppm), 6 times the maximum permissible limit (MPL); within the city well 54 located in the western sector had the highest value (0.076 ppm), 3 times the MPL, 67% of the wells in the city and 60% of the Guadiana Valley had levels that exceeded the MPL (0.025 ppm), the concentration in the city ranged from 0.009 to 0.149 ppm and from 0.08 to 0.15 ppm for the rural zone. With respect to F − , the highest value was also found in the Colonia Hidalgo well (17.8 mg/L), 12 times the MPL; within the city the highest value was recorded in well 16 in the eastern sector with 7.6 ppm (5 times the MPL) 97% of the wells in the city and 100% of the wells in the Guadiana Valley rural area had concentrations greater than MPL (1.5 ppm), the concentration in the city ranged from 1.1 to 7.6 ppm, while in the Guadiana Valley from 1.7 to 17.8 ppm. Statistical analysis showed no significant difference for fluoride concentration over time (1996-2013); whereas the concentration of arsenic decreased, probably due to the degree of precision required for such small concentrations in groundwater and different analysts ran the samples.