PHYSICAL-CHEMICAL QUALITY OF THE SURFACE WATERS OF THE RIO VIEJO SUB-BASIN

Abstract

The water quality was evaluated from the physical-chemical perspective, from nutrients, from the content of the contamination indicator variables for organic matter (BOD5 and COD), as well as from metallic and organic contaminants in the superficial sources of the Rio Viejo sub-basin in relation to its adaptability for different uses.

The results of the physical - chemical analysis, almost in all the sampling sites, revealed values ​​that provide the water with optimal characteristics in terms of its use for irrigation, recreation and protection of aquatic life, being particularly for El Jordán of good quality for human consumption, however; it is important to contrast with the microbiological indicators of contamination.

Metal contaminants (cadmium, arsenic and mercury) were detected in some sites at slightly higher concentrations than the limit of detection of analytical methods, being much lower than the reference values ​​for unpolluted waters, which presumes their natural origin. The detection of pesticides Piedrín and Endrín, in values ​​similar to those recommended for the protection of aquatic life, suggests that it is a product, in addition to the persistence of these in the soil due to its extensive use in the past, of current uses nonetheless its prohibition.

In general, all the sampling sites presented a different degree of affectation due to the external contribution of nutrients; however, the urban center of Trinidad was exceptionally identified as the site under environmentally critical conditions in its position of natural receiver of domestic wastewater with high levels of BOD5 and COD, as well as the presence of several organochlorine compounds.