Néstor Aguirre

Optimal conditions for chlorpyrifos and dissolved organic carbon removal in subsurface flow constructed wetlands

This work used subsurface flow constructed wetlands, planted with Phragmites australis, using 2 water depths and 2 sizes of granular material, in order to find the optimal conditions for the removal of chlorpyrifos and dissolved organic carbon (DOC) from synthetic wastewater. In addition, some bacterial groups were identified which formed the biofilm present in subsurface flow constructed wetlands used in the removal of chlorpyrifos. In samples taken from influents and effluents of the wetlands, chlorpyrifos was quantified by gas chromatography (GC µ-ECD), DOC by an organic carbon analyser and bacterial groups using conventional microbiology, according to Standard Methods. The highest values of chlorpyrifos (97.9%) and DOC (80.1%) removal were found with granular material having diameters within 3.18–6.35 mm and according to water column depth (0.4 m) were 97.8% and 79.7%, respectively. The bacterial groups quantified in the biofilm were total heterotrophic, revivable heterotrophic, total coliforms, facultative sporulated, Pseudomonads, denitrifying bacteria and sulphate-reducing bacteria. Some bacteria showed little development, probably due to the pesticide and/or the anaerobic conditions of the systems (negative redox potential and dissolved oxygen (DO) concentrations approaching zero). It was proven that subsurface flow constructed wetlands, in adequate conditions, are able to eliminate organic matter and chlorpyrifos.

Epiphyton Colonization on Artificial Substrates in the Aburrá -Medellin River, Colombia

This work aims at determining the effect of wastewater input and hydrologic regimes on the epilithic algal colonization over artificial substrates in the Aburra–Medellin River. For this purpose, at eight stations in the river were installed 14 polypropylene baskets with 2000 grams of gravel as substrates in order to know the algae response to changes in water quality (reflected in changes in biological indices and also affected by fluctuations in water levels; i.e., flow rates, and therefore changes in its composition according to the hydrological cycle). Alterations generated in the composition and abundance of algae by wastewater discharges and change in water levels did not produce a pattern of colonization. Based on the above, it allowed to conclude that algae are sensitive organisms to particular events that affect water quality in the Aburra–Medellin River. KeywordsEpiphyton; Colonization; Algae; Water Quality of Aburra-Medellin River

Aproximación multivariada a la dinámica del ensamblaje algal epifítico en un sistema de planos inundables tropica

Objective: Identify dynamics of periphytic algal assembly through flood pulse during three hydrological cycles on a tropical flood plain. Materials and methods: In different phases of flood pulse between 2006 and 2009, nine samplings were carried out which evaluated the spatial and temporal variation of epiphytic algal assemblage associated with macrophytes roots in 14 sites of sampling, 7 zones with lentic and 7 lotic conditions of the Ayapel flood plain were taken at different stages of the flood pulse between 2006 and 2009. Macrophytes roots were taken in lugol, in which it was observed epiphytic algal assemblage, what allowed the multivariate study of their dynamic. Results: Similarity floristic between the algae assemblages was low and denoted specificity of species that inhabit each of these compartments of the system. A majority location of species around the ammonium was observed in both systems. The few species or genera that are repeated between two ecosystems are ordered with respect to different conditions, which may be associated with the degree of adaptation of organisms to environmental conditions.