Resumo

MUNOZ-NAVA, Hipólito et al. Chemical oxygen demand and population in the Zahuapan river sub-basin, Tlaxcala, Mexico. Rev. Int. Contam. Ambient [online]. 2012, vol.28, n.1, pp.27-38. ISSN 0188-4999.

River pollution is an environmental concern in Mexico. The sources of organic material are diverse, and include agricultural and industrial activity, as well as urban and rural wastewater. The aim of this study was to examine the correlation between organic material (biochemical oxygen demand, BOD) and human population in the Zahuapan river subbasin. Twelve points were selected for monthly river stream sampling, for a period of one year. Eleven physicochemical properties based on the corresponding official Mexican standards were measured. Speed, width and depth of the stream were measured every 20 cm during the dry season, in order to calculate the hydraulic cross section and hydraulic load of the river. The microbasins of the sampling points were defined using the TAS software. The towns in each microbasin were grouped by population and distance from the watercourse. Correlations of r² > 0.8 were found in microbasins with little industrial or agricultural activity. The correlation between BOD and chemical oxygen demand (COD) was the highest, with r² = 0.733. The population living in the Zahuapan river subbasin is approximately 523 830, which represents 59 % of Tlaxcala's state population. Of the population living in the influence area of the sampling points, 67 % live in towns with a population 1001-5000 or 20 001-50 000 inhabitants. A considerable proportion of the calculated BOD load is explained by populations located within 20 km radium from the river.

Palavras-chave : pollution; microbasin; correlation.

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