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 algae 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 (minor to 1.2μm). Percentage inhibition of algal growth (per cetn Iw) was estimated as the differences between cultures with and without EDTA additions in the filtered water samples. Concentrations of Cd (1-85ug.L-1), Cr (3-164ug.L-1), and Ni (10-99ug.L-1) in river waters were always lower than the respective EC50 for P. subcapitata, whereas concentrations of Cu (5-306ug.L-1), Pb (13-546ug.L-1), and Zn (4-380μg.L-1) in dissolved fractions resulted above the EC50 values in many samples. Only 10 samples showed algal growth inhibition (between 11.21per cent and 42.19 per cent), 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 per cent Iw values between 10.03 per cent and 90.51 per cent. 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.
Magdaleno, A.; Cabo, L. de; Arreghini, S. & Salinas, C. (2014). Assessment of heavy metal contamination and water quality in an urban river from Argentina. Brazilian Journal of Aquatic Science and Technology,18, (1),p.113-120
10.14210/bjast.v18n1.p113-120
Magdaleno, Anahí, Cabo, Laura de, Arreghini, Silvana, Salinas, Cristian. 2014. "Assessment of heavy metal contamination and water quality in an urban river from Argentina". Brazilian Journal of Aquatic Science and Technology 18, no.1:113-120.
Recuperado de http://ri.agro.uba.ar/greenstone3/library/collection/arti/document/2014magdaleno