INVESTIGADORES
DE CABO Laura Isabel
artículos
Título:
Water toxicity and metal contamination assessment of a polluted urban river
Autor/es:
MAGDALENO A.; DE CABO, L; ARREGHINI S.; SALINAS, C
Revista:
Brazilian Journal of Aquatic Science and Technology-BJAST
Editorial:
UNIVALI
Referencias:
Lugar: Rio Grande do Sul; Año: 2014
ISSN:
1808-7035
Resumen:
In aquatic ecosystems, the potential effects of
toxic compounds are greatly determined by their physicochemical forms and
bioavailability. The aim of this work was the assessment of metal toxicity to the
green alga Pseudokirchneriella
subcapitata in contaminated water samples of an urban river (Matanza-Riachuelo, Argentina). A total of 30 samples
were analyzed. Physicochemical parameters and total and dissolved metal (Cd,
Cu, Cr, Pb, Ni and Zn) concentrations were measured. Toxicity was related as a
function of size fractionation and chemical speciation (using the program
Mineql+) in the dissolved fraction (< 1.2 μm). Percentage inhibition of algal
growth (%Iw) was estimated as the differences between cultures with and without
EDTA additions in the filtered water samples. Concentrations of Cd
(1 - 85 μg/L), Cr (3 - 164 μg/L), and Ni (10 - 99 μg/L) in river waters were
always lower than the respective EC50 for P.
subcapitata, whereas concentrations of Cu (5 - 306 μg/L), Pb (13 - 546 μg/L),
and Zn (4 - 380 μg/L) in dissolved fractions resulted above the EC50 values
in many samples. Only 10 samples showed algal growth inhibition (between 11.21 %
and 42.19 %), which 8 of them also showed high concentrations of free ionic
forms of Pd or Zn. Free ionic concentrations of Cu were always lower than the
EC50 for the algae. Two samples resulted toxic to P. subcapitata in spite of
the absence of toxic metal concentrations. Besides, 13 samples no inhibited the
algal growth and high concentrations of Pd and Zn were obtained, producing expected %Iw values between 10.03
% and 90.51 %. The absence of toxicity in most samples with toxic metal concentrations
could be related to the presence of organic ligands, colloidal organic matter,
and antagonism effects among other metals,
which reduce their bioavailability.