Assessment of heavy metal contamination and water quality in an urban river from Argentina

Abstract

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 (<1.2μm). 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 (1-85μg.L -1 ), Cr (3-164μg.L -1 ), and Ni (10-99μg.L -1 ) in river waters were always lower than the respective EC50 for P. subcapitata, whereas concentrations of Cu (5-306μg.L -1 ), Pb (13-546μg.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 11.21% 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.

Remediation of Eutrophic Aquatic Ecosystems: Evaluation of Phosphorus Adsorption by Sawdust

“…In treatment microcosms, the dissolved O concentrations were significantly lower ( p < 0.05) than in the control microcosms as a consequence of the oxidation of the organic matter (sawdust) present in treatment microcosms; organic matter consumes the O in the water as it decays (Cunha‐Santino and Bianchini Jr 2003; Magdaleno et al ; Su et al ).…”

“…The presence of the biosorbent is responsible for the higher concentration of DOC determined in the water column in the treatment flasks. Dissolved O promoted the oxidation of organic matter, so a decreasing tendency of this parameter was observed (Cunha‐Santino and Bianchini Jr ; Magdaleno et al ; Su et al ). From the statistical analysis, it was possible to observe that there was a significant variation ( p < 0.05) between control and treatment microcosms in the water column and interstitial water; incubation time and treatment had a significant influence on DOC values.…”

Rehabilitación de las riberas de un sitio de la cuenca baja del río Matanza-Riachuelo

“…Sumado a esto, la mejora, en cuanto a la revaloración de los aspectos social, económico, estético y cultural, es de gran relevancia en los ambientes con fuerte influencia antrópica (Schanze et al, 2004). El río Matanza-Riachuelo, es un río cuyas características hidrológicas no facilitan la evacuación de las cargas de contaminantes y ha sido clasificado como uno de los más contaminados del mundo (Magdaleno et al, 2014). La contaminación que afecta a este sistema es mixta: recibe efluentes líquidos y desechos tanto de origen industrial como doméstico, encontrándose entre estos últimos desechos cloacales y líquidos lixiviados de basurales que percolan a la napa freática y eventualmente descargan en el río.…”

Utilización de Sustancias Húmicas Comerciales para Optimizar la Fitorremediación de Suelos Mineros Usando Vetiveria (Chrysopogon zizanioides L. Roberty) y Verdolaga (Atriplex portulacoides L.)

“…Dentro de los metales pesados, los fácilmente extraíbles en un ecosistema acuático son Mn, Zn, Cd y Pb (Magdaleno et al, 2014), siendo la cantidad de metales pesados asimilables dependen de la especie y del estado de la misma (Herrera Murillo y Rodríguez Román, 2010). Miranda et al, 1996).…”