RESUMO
Abstract The reservoirs of the upper Juramento basin (Cabra Corral and El Tunal) and the Salí-Dulce basin (El Cadillal, Río Hondo, and Escaba) show certain peculiarities due to their geographical location, basin morphology and limnological features. Such peculiarities were compared during significant algal bloom periods between 2002 and 2008, by analyzing the main physicochemical parameters and ecological attributes of the phytoplankton assemblages using standard methods. Tucumán reservoirs were different in most variables showing higher values of conductivity, nutrients and algal biomass. Regarding the hydrological cycle, El Cadillal exhibited the lowest biomass average (2.74 mg Chl.m-3) during maximum water flows, whereas the Cabra Corral lacustrine zone exhibited the highest biomass average (63.36 mg Chl.m-3) during minimum water flows. For the same period, the Cabra Corral lacustrine zone exhibited lower phytoplankton diversity and richness (1.37 and 9, respectively), in accordance with dinophyte blooms of Ceratium sp. In all reservoirs, the following biological variables showed a significant contrast in the hydrological cycle: highest phytoplankton biomass during minimum water flows (35.68 mg Chl-a m-3) vs. waterfloods (13.68 mg Chl-a m-3) (T = 3.42, P = 0.001). During minimum water flows, richness (14.30 sp.) and equitability (0.51) were lower vs. waterfloods (20.23, 0.59, respectively) (T = 2.36; P = 0.0196), as a result of the allochthonous nutrients provided by the main tributaries. Management of the reservoirs' hydrometric levels during dry season determines the deterioration of the water quality with increased algal blooms. In order to ensure the systems' sustainability, eutrophication must be controlled with programs to reduce diffuse nutrient loads and to treat residential and agroindustrial effluents, particularly in Sali-Dulce basin. Rev. Biol. Trop. 66(1): 415-427. Epub 2018 March 01.
Resumen Los embalses de la Alta Cuenca del Juramento (Cabra Corral y El Tunal) y del Salí-Dulce (El Cadillal, Río Hondo y Escaba) por su ubicación geográfica, morfología y características limnológicas muestran ciertas peculiaridades que son comparadas en el período relevante de proliferaciones algales acaecidas entre 2002 y 2008, mediante análisis de los principales parámetros fisicoquímicos y atributos ecológicos de los ensambles del fitoplancton por empleo de técnicas estandarizadas. Los embalses de Tucumán se diferenciaron en la mayoría de las variables con valores más elevados de conductividad, nutrientes y biomasa de algas. En función del ciclo hidrológico, El Cadillal en aguas altas presentó el promedio más bajo de biomasa (2.74 mg Cl.m-3) y en contraste Cabra Corral el más elevado (63.36 mgCl.m-3) durante los caudales mínimos de agua. En éste último, en el mismo período, también la diversidad y riqueza de especies del fitoplancton fueron menores (1.37 y 9 respectivamente), en concordancia con las proliferaciones de dinófitos (Ceratium sp.). Las siguientes variables biológicas en el conjunto de embalses presentaron un contraste significativo en el ciclo hidrológico: biomasa del fitoplancton más elevada en estiaje (35.68 mg Cl a. m-3) versus crecidas (13.68 mg Cl a. m-3) (T = 3.42; P = 0.001). En estiaje, la riqueza (14.30 sp) y equitatividad (0.51) fueron menores versus crecidas (20.23, 0.59, respectivamente) (T = 2.36; P = 0.0196), debido al aporte alóctono de nutrientes por los tributarios principales. El manejo de los niveles hidrométricos de los embalses durante el estiaje determina el deterioro de la calidad de sus aguas con incremento de proliferaciones algales. Para asegurar la sustentabilidad de los sistemas, es indispensable el control de la eutrofización mediante programas de reducción de cargas difusas de nutrientes y tratamiento de efluentes domiciliarios y agroindustriales, particularmente en la cuenca del Sali-Dulce.
RESUMO
Argentina is a developing Latin American nation that has an aim of achieving the United Nations Millennium Development Goals for potable water supplies. Their current regulations however, limit the continued development of improved potable water quality and infrastructure from a microbiological viewpoint. This is since the current regulations are focused solely to pathogenic Eschericia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and fecal indicators. Regions of lower socioeconomic status such as peri-urban areas are particularly at risk due to lessened financial and political ability to influence their environmental quality and infrastructure needs. Therefore, a combined microbiological sampling, analysis and quantitative microbial risk assessment (QMRA) modeling effort were engaged for a peri-urban area of Salta Argentina. Drinking water samples from home taps were analyzed and a QMRA model was developed, results of which were compared against a general 1:10,000 risk level for lack of a current Argentinian standard. This QMRA model was able to demonstrate that the current regulations were being achieved for E. coli but were less than acceptable for P. aeruginosa in some instances. Appropriate health protections are far from acceptable for Giardia for almost all water sources. Untreated water sources were sampled and analyzed then QMRA modeled as well, since a significant number of the community (â¼9%) still use them for potable water supplies. For untreated water E. coli risks were near 1:10,000, however, P. aeruginosa and Giardia risks failed to be acceptable in almost all instances. The QMRA model and microbiological analyses demonstrate the need for improved regulatory efforts for the peri-urban area along with improved investment in their water infrastructure.
