Resumo

MONTES, Raquel T.; NAVARRO, Inés; DOMINGUEZ, Ramón  e  JIMENEZ, Blanca. Changes in the self-purification capacity of the Magdalena River due to climate change. Tecnol. cienc. agua [online]. 2013, vol.4, n.5, pp.71-83. ISSN 2007-2422.

This work studied the possible effect of increased temperatures and future variations in precipitation on the self-purification capacity of the Magdalena River, which feeds one of the treatment plants in Mexico City. The impact of climate variability resulting from current conditions as well as climate change scenarios during rainy and dry periods was measured with the Streeter-Phelps model. The current scenario was evaluated with historical data, sampling campaigns (2010-2011) and climatological data (1967-1996). Projections for dissolved oxygen (DO) and biological oxygen demand (BOD) were obtained based on the behavior of the current scenario, and projections for precipitation and temperature were obtained for scenarios A1B, A2 and B1using two general circulation models for the year 2020. For the current as well as climate change scenarios, the dry period was determined to be the most critical season for the degradation of BOD, with removal percentages between 6.8 and 13.4%, though with higher percentages (13%) for recovery for DO. Biodegradability was found to be lower (4.3 - 6%) during the rainy season than the dry season, with recovery of DO < 7.7%. The results show the need for regular monitoring of water quality and the variation in river flow, especially during the dry season, since critical conditions could occur that affect the efficiency of treatment, such as hot temperatures and less flow.

Palavras-chave : climate change; dissolved oxygen; self-purification of rivers; water quality.