Contamination Alters the Physicochemical and Textural Characteristics of Clays in the Sediments of the Peri Urban Reconquista River, Affecting the Associated Indigenous Microorganisms

Abstract

The physicochemical and textural characteristics of river sediments and, essentially, their clays, are at the center of a network of biological and geochemical factors that are mutually modifying. Therefore, the contamination, the characteristics of the clays, and the associated microorganisms strongly influence each other. In this work, sediments from two sites of the urban Reconquista River, near Buenos Aires City, Argentina, exposed to different environmental contexts were characterized. The huge differences in the organic matter content in the vertical profile between both sediments strongly evidenced the polluted status of San Francisco (SF) site as opposed to the Dique Roggero (DR) site. Thorough physicochemical and textural characterization of the sediments and their clay fraction performed by pH, Oxidation-reduction potential (ORP), spectrophotometry, XRD, laser diffraction, N2 adsorption–desorption isotherms, EDS, and SEM measurements revealed that organic matter (DR: 41 ± 5 g kg−1; SF: 150 ± 30 g kg−1) intervened in the retention of heavy metals (DR: 5.6 mg kg−1 Zn, 7 mg kg−1 Cu, 3.1 kg−1 Cr; SF: 240 mg kg−1 Zn, 60 mg kg−1 Cu, 270 mg kg−1 Cr) and affected the level of association and the formation of mineral–organic aggregates (DR: 15 ± 3 μm; SF: 23 ± 4 μm). This can be decisive in the surface interaction required for the establishment of bacterial assemblages, which determine the biogeochemical processes occurring in sediments and have a key role in the fate of contaminants in situ and in the remediation processes that need to be applied to restore the anoxic contaminated sediments.

Streambed pollution: A comprehensive review of its sources, eco-hydro-geo-chemical impacts, assessment, and mitigation strategies

“…Prolonged exposure of streambed sediments to the contaminants could eventually alter the chemical properties of the sediments [170]. For instance, in Oak Ridge, USA, after the historical industrial releases of mercury (Hg) in the East Fork Poplar Creek, a study has found evidences of geochemical transformation of sediments into Hg-bound sediments and degradation of in-stream environment [171].…”

Wiring Up Along Electrodes for Biofilm Formation

“…Under the low redox potential of the rivers water, heavy metals are precipitated or adsorbed on different mineral components of the sediment, turning it into a heavy metal reservoir (Porzionato et al, 2013). A thorough characterization of the rivers water and sediment was previously performed by our group (Tufo et al, 2018(Tufo et al, , 2021. The Reconquista river has high levels of chromium, among other diverse pollutants, and being the second most polluted river in Argentina it represents an acute environmental problem (Porzionato et al, 2016).…”

Geochemical characterization and the assessment of trace element retention in sediments of the Reconquista River, Argentina

“…It has thus become a typical example of the adverse impact of human activities on the health of aquatic environment (Salibia ´n, 2006). Previous studies (Nader, 2015;Ossana et al, 2013Ossana et al, , 2016Rigacci et al, 2013;Tufo et al, 2021;and references therein) have determined that trace elements such as chromium (Cr), cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn) and arsenic (As) are the main pollutants in the water of the Reconquista River. The introduction of these trace elements is a consequence of the waste of fossil fuel combustion, leakage of metal-containing motor oils and untreated sewage discharged by electroplating, electrical, paint, food, tannery, chemistry and nonferrous smelting industries (Mondino, 2007;Pescuma & Guaresmi, 1992).…”

“…Many authors have studied their toxicological impacts on the biota (Herkovits et al, 1996;Loez & Topalia ´n, 1999;Ossana et al, 2013Ossana et al, , 2016Rigacci et al, 2013). Of note, heavy metals retained in sediment particles (Cantera et al, 2018;Tufo et al, 2021) may eventually be released to water and generate adverse effects in exposed animals and humans (e.g., Ferraro et al, 2012).…”