Matanza-Riachuelo River Research Articles

Assessment of toxic metal contamination using a regional lithogenic geochemical background, Pampean area river basin, Argentina

Contamination assessment in riverbed sediments depends on the accurate determination of the background values. The aim of this study is to assess the degree of contamination and to evaluate the most adequate background for the determination of anthropogenic contamination in Cd, Cr, Cu, Ni, Pb and Zn in bed sediments of the Pampean area river basin (Matanza-Riachuelo River and tributary streams), Argentina. The geo-accumulation index (Igeo) values were calculated using selected lithogenic backgrounds (loess, loessoid sediments and paleosoils), the metal concentrations in the residual fraction (F4) in riverbed sediments and a global average shale often applied in the estimation of toxic metal Igeo. The IgeoF4, IgeoLZB and most of the others Igeos, indicated that in land areas used mainly for agriculture and cattle grazing, the superficial sediments were uncontaminated with Cd, Cr, Cu and Zn, and slightly contaminated with Ni and Pb. Conversely, in those areas dedicated to urban and industrial use, the metal contamination was greater. Overall, the relatively significant anthropogenic contamination of Cr > Pb ≥ Cu > Zn > Ni > Cd in the Riachuelo River area was associated with metallurgic activities, tanning and industrial waste. The comparative analysis of different values suggested that Buenos Aires’ “pristine” loess could be recommended to evaluate the Igeo index of riverbed sediments in the Pampean area. To enhance the use of the selected background, the normalized enrichment factor using Al. In this study case, the Igeo and the EF using LZB background display the same trend, showing the greatest degree of contamination, as would be expected, in Riachuelo samples (RIA 1 and RIA 2) located in the urban/industrial area.

Applying reactive transport modelling in a chromium-contaminated site in the Matanza-Riachuelo basin, Buenos Aires, Argentina

Chromium (Cr) is one of the main pollutants affecting both soil and groundwater systems in some areas within the Matanza-Riachuelo River Basin (MRB) in Argentina. The particular site of study is located near an abandoned tannery and chemical industry facilities. Cr toxicity and mobility depend on its oxidation state: Cr(VI) is an active carcinogen, more soluble and mobile, whereas Cr(III) shows low toxicity and solubility, precipitating in the form of amorphous Cr(OH)3(am). This paper is devoted to elucidate the main key controls on the Cr(VI)-plume transport at this site using reactive transport (RT) modelling and uncertainty quantification analysis tools. RT results suggest a Cr source term on the surface to explain the observed Cr concentrations in both Pampeano and Puelche aquifers. UQ analysis indicates that the Cr(VI) concentrations in both aquifers are sensitive to hydraulic connectivity between them, the reaction reduction rates Cr(VI)-Cr(III) and the organic matter contents.

ENVIRONMENTAL CONFLICTS AND PUBLIC DELIBERATION ARENAS AROUND THE ENVIRONMENTAL ISSUE IN ARGENTINA

ABSTRACT The purpose of this work is to analyze the way in which various collective actions have given way to new public deliberation arenas around the environmental issue in Argentina. On the basis of the results of a study on the ‘‘conflict over the pulp mills on the Uruguay River” and the ‘‘conflict over the environmental restoration of the Matanza-Riachuelo River basin,” our intention is to delve into a theoretical perspective that takes into account the productivity of these events and to analyze different forms of contagion among public arenas. By presenting the results of the case studies, we will refer to the territorial productivity of environmental conflicts.

Identifying and quantifying geochemical and mixing processes in the Matanza-Riachuelo Aquifer System, Argentina

The Matanza-Riachuelo River Basin, in the Northeast of the Buenos Aires Province, is one of the most industrialized and populated region in Argentina and it is worldwide known for its alarming environmental degradation. In order to prevent further damages, the aquifer system, which consists of two overlaid aquifers, is being monitored from 2008 by the river basin authority, Autoridad de la Cuenca Matanza-Riachuelo. The groundwater chemical baseline has been established in a previous paper (Zabala et al., 2016), and this one is devoted to the identification of the main physical and hydrogeochemical processes that control groundwater chemistry and its areal distribution. Thirty five representative groundwater samples from the Upper Aquifer and thirty four from the deep Puelche Aquifer have been studied with a multi-tool approach to understand the origin of their chemical and isotopic values. The resulting conceptual model has been validated though hydrogeochemical modeling. Most of the aquifer system has fresh groundwater, but some areas have brackish and salt groundwater. Water recharging the Upper Aquifer is of the Ca-HCO3 type as a result of soil CO2 and carbonate dissolution. Evapotranspiration plays a great role concentrating recharge water. After recharge, groundwater becomes Na-HCO3, mostly due to cation exchange with Na release and Ca uptake, which induces calcite dissolution. Saline groundwaters exist in the lower and upper sectors of the basin as a result of Na-HCO3 water mixing with marine water of different origins. In the upper reaches, besides mixing with connate sea water other sources of SO4 exist, most probably gypsum and/or sulfides. This work highlights the relevance of performing detailed studies to understand the processes controlling groundwater chemistry at regional scale. Moreover, it is a step forward in the knowledge of the aquifer system, and provides a sound scientific basis to design effective management programs and recovery plans.

Ecología política del agua y territorialización de las luchas sociales. La experiencia del foro hídrico de Lomas de Zamora

This article we develops an analysis of collective action for water access and sanitation in the Buenos Aires metropolis. It intends to give an account of the social and political construction of water issue. To this end, it analyzes the emergence of conflicts and claims for environmental justice that create new knowledge about the hydrosocial cycle. The research was based on a case study that examines the experience of the «Foro Hidrico de Lomas de Zamora» (Lomas de Zamora Water Forum), an organization developing actions in the lower basin of the Matanza-Riachuelo river. The results of the study show the political resonance of these actions in terms of the territorialization of conflicts and the production of counter-expertise knowledge. We aim to show the resonance that this experience has in collective organization and the construction of new languages of rights.

Toxicity and genotoxicity assessment in sediments from the Matanza-Riachuelo river basin (Argentina) under the influence of heavy metals and organic contaminants

The aim of this study was to investigate the parameters of chemical extraction associated with the detection of toxicity and genotoxicity in sediment sample extracts. Quantitative analysis of metals and polycyclic aromatic hydrocarbons (PAHs), together with a battery of four bioassays, was performed in order to evaluate the extraction efficiency of inorganic and organic toxicants. The extracts were carried out using two inorganic solvents, two organic solvents and two extraction methodologies, making a total of five extracts. Two toxicity tests, the algal growth inhibition of Pseudokirchneriella subcapitata and the root elongation inhibition of Lactuca sativa, and two genotoxicity tests, the analysis of revertants of Salmonella typhimurium and the analysis of micronuclei and chromosomal aberrations in Allium cepa, were performed. According to the chemical analysis, the acidic solution extracted more heavy metal concentrations than distilled water, and dichloromethane extracted more but fewer concentrations of PAH compounds than methanol. Shaker extracts with distilled water were non-toxic to P. subcapitata, but were toxic to L. sativa. The acidic extracts were more toxic to P. subcapitata than to L. sativa. The methanolic organic extracts were more toxic to the alga than those obtained with dichloromethane. None of these extracts resulted toxic to L. sativa. Mutagenic effects were only detected in the organic dichloromethane extracts in the presence of metabolic activation. All the inorganic and organic extracts were genotoxic to A. cepa. This study showed that the implementation of different extraction methods together with a battery of bioassays could be suitable tools for detecting toxicity and genotoxicity in sediment samples.

Assessment of child psychomotor development in population groups as a positive health indicator.

It is necessary to use health indicators describing the conditions of all individuals in a population, not just of those who have a disease or die. To introduce a method to collect population indicators of psychomotor development in children younger than 6 years old and show its results. Data were obtained from a cross-sectional assessment regarding compliance with 13 developmental milestones (selected from the national reference) conducted in 5465 children using five surveys administered by the Matanza-Riachuelo River Basin Authority in areas of this basin where a high proportion of families with unmet basic needs live. For each survey, a logistic regression analysis was used to estimate the median age at attainment of the 13 developmental milestones. A linear regression model between the estimated age at attainment of the 13 milestones was adjusted for each survey based on the corresponding age at attainment of the national reference. Based on this model, three indicators were defined: overall developmental quotient, developmental quotient at 4 years old, and developmental trend. Results from the five surveys ranged between 0.74 and 0.85, 0.88 and 0.81, and -0.15 and -0.26 for the overall developmental quotient, developmental quotient at 4 years old, and developmental trend, respectively. A distinct developmental delay and an increasing trend in delay with age were observed. Indicators are easily interpreted and related to social indicators (unmet basic needs, etc.). Collecting the information necessary to make estimations takes little time and can be applied to population groups, but not on an individual level.

Groundwater chemical baseline values to assess the Recovery Plan in the Matanza-Riachuelo River basin, Argentina

The two most exploited aquifers in the Matanza-Riachuelo River basin are being monitored in the framework of the Integrated Environmental Sanitation Plan that implements the Basin Authority, Autoridad de Cuenca Matanza Riachuelo. In this context, this work identifies the groundwater chemical types and the natural processes behind them; determines spatial and temporal changes; establishes ranges of variation for chemical components, and proposes concentration values for the upper limit of the natural chemical background. A total of 1007 samples from three aquifer-layers (Upper Aquifer, top and bottom of Puelche Aquifer) have been studied. As concrete guidelines for practical determination of baseline values are not available in the region, the methodology used follows the proposals of European projects which assessed European water directives.The groundwater composition is very stable in terms of both chemical facies and mineralization degree, and the changes observed in the dry and wet periods analysed are subtle in general. Most of the groundwater is Na-HCO3 type, except a few samples that are Ca-HCO3, Na-ClSO4 and Na-Cl types. The Ca-HCO3 waters are the result of calcium carbonate dissolution, Na-HCO3 waters result from cation exchange and carbonate dissolution, while in the Na-ClSO4 and Na-Cl waters, mixing with connate and with encroached old marine water from the underlying and overlying sediments are the most relevant processes. The proposed values for the upper limit of the natural background consider the influence of geology and Holocene marine ingressions in the baseline of coastal groundwater.This study allowed to know the initial chemical conditions of the groundwater system of the Matanza-Riachuelo River basin and to establish the reference from which Basin Authority can start to evaluate trends and monitor the recovery plan. At the same time, it sets a precedent for future studies in the region.

High diversity of human polyomaviruses in environmental and clinical samples in Argentina: Detection of JC, BK, Merkel-cell, Malawi, and human 6 and 7 polyomaviruses

New human polyomaviruses have been recently described. The aim of this work was to detect and characterize human polyomaviruses circulating in Argentina by recovering viruses from environmental and sewage samples and evaluating their potential role as viral indicators of human waste contamination. Analysis was performed in a wider context including viruses from clinical samples from an immunocompromised population. River water and sewage samples were analyzed as a strategy to study the molecular epidemiology of viruses excreted by millions of people. Samples belonged to the Matanza-Riachuelo River (2005–2006: n=25 and 2012: n=20) and sewage from Buenos Aires city and suburbs (2011 and 2013: n=24). Viral detection was performed by PCR and the amplified viral genomes were characterized by phylogenetic analysis. Polyomaviruses were detected in 95.8% of sewage samples, identifying BKPyV (87.5%), JCPyV (83.3%), MCPyV (8.3%) and HPyV6 (8.3%). Besides, one sample collected in 2009 resulted positive for HPyV7. In 2005–2006, polyomaviruses were detected in 84.0% of river water samples, with the highest detection for MCPyV (52.0%), followed by BKPyV (44.0%), JCPyV (20.0%) and MWPyV (4.0%). In 2012, polyomaviruses were detected in 85.0% of river samples, finding JCPyV (85.0%), BKPyV (75.0%), MCPyV (25.0%) and HPyV6 (25.0%). Also, polyomaviruses, including JCPyV, BKPyV and MCPyV, were detected in 63.2% of urine samples from patients infected with HIV (n=19). Characterization indicated the coexistence of different genotypes and variants for each virus, particularly in sewage. MCPyV sequences (the only sequences from Argentina) formed a monophyletic group with the single sequence available for South America (French Guiana). The high level of detection and viral diversity found by environmental surveillance, which involved the characterization of viruses not previously described in South America, reinforces the usefulness of this approach to monitor viral contamination and describe the viral epidemiology in the general population.

The interaction of heavy metals and nutrients present in soil and native plants with arbuscular mycorrhizae on the riverside in the Matanza-Riachuelo River Basin (Argentina)

This study assessed the contamination by heavy metals (Cr, Cu, Pb, Zn), and nutrients (N, P) in soils and native plants, and the effect of the concentration of those elements with the density of arbuscular-mycorrhizal (AM) spores in soil and colonization in roots from the riverside of the Matanza-Riachuelo River Basin (MRRB). The concentration of metals and nutrients in soils and plants (Eleocharis montana, Cyperus eragrostis, Hydrocotyle bonariensis) increased from the upper sites (8km from headwaters) to the lower sites (6km from the mouth of the Riachuelo River) of the basin. AM-colonization on the roots of H. bonariensis and spore density in soil decreased as the concentrations of metals in soil and plant tissues increased from the upper to lower sites of the basin within a consistent gradient of contamination associated with land use, soil disturbance, population, and chemicals discharged into the streams and rivers along the MRRB. The general trends for all metals in plant tissue were to have highest concentrations in roots, then in rhizomes and lowest in aerial biomass. The translocation (TF) and bioconcentration (BCF) factors decreased in plants which grow from the upper sites to the lower sites of the basin. The plants tolerated a wide range in type and quantity of contamination along the basin by concentrating more metals and nutrients in roots than in aboveground tissue. The AM spore density in soil and colonization in roots of H. bonariensis decreased with the increase of the degree of contamination (Dc) in soil.

Effects of Cadmium, Copper and Zinc on Growth of Four Isolated Algae from a Highly Polluted Argentina River

Toxicity of cadmium, copper and zinc was tested on four green algal species (Ankistrodesmus fusiformis, Chlorella ellipsoidea, Monoraphidium contortum and Scenedesmus acuminatus) isolated from a highly polluted river (Matanza-Riachuelo River, Buenos Aires, Argentina). The relative abundance of these species in river waters showed that C. ellipsoidea was the most abundant species (mean 4,540 ind mL(-1)), whereas the less abundant species was S. acuminatus (mean 220 ind mL(-1)). The most sensitive species was A. fusiformis, which EC50 were Cd = 141 μg L(-1), Cu = 72 μg L(-1), and Zn = 199 μg L(-1), whereas C. ellipsoidea was the most resistant species to copper (EC50 = 489 μg L(-1)) and cadmium (EC50 = 429 μg L(-1)), and M. contortum and S. acuminatus were the most resistant species to zinc (EC50 = 381 and 394 μg L(-1), respectively).

The origin and quality of water for human consumption: the health of the population residing in the Matanza-Riachuelo river basin area in Greater Buenos Aires.

The aim of this study is to analyze the origin and quality of water used for consumption in a sample of households in Matanza-Riachuelo river basin area in Greater Buenos Aires, Argentina. The results of drinking water by source indicated that 9% of water samples from the public water system, 45% of bottled water samples and 80% of well water samples were not safe for drinking due to excess content of coliforms, Escherichia coli or nitrates. Individuals living in households where well water is the main source of drinking water have a 55% higher chance of suffering a water-borne disease; in the cases of diarrheas, the probability is 87% higher and in the case of dermatitis, 160% higher. The water for human consumption in this region should be provided by centralized sources that assure control over the quality of the water.

Origen y calidad del agua para consumo humano: salud de la población residente en el área de la cuenca Matanza-Riachuelo del Gran Buenos Aires

The aim of this study is to analyze the origin and quality of water used for consumption in a sample of households in Matanza-Riachuelo river basin area in Greater Buenos Aires, Argentina. The results of drinking water by source indicated that 9% of water samples from the public water system, 45% of bottled water samples and 80% of well water samples were not safe for drinking due to excess content of coliforms, Escherichia coli or nitrates. Individuals living in households where well water is the main source of drinking water have a 55% higher chance of suffering a water-borne disease; in the cases of diarrheas, the probability is 87% higher and in the case of dermatitis, 160% higher. The water for human consumption in this region should be provided by centralized sources that assure control over the quality of the water.

The Constitutional Right to a Healthy Environment

Do people have a right to clean air, safe drinking water, and a healthy environment? Fifty years ago, the concept of a human right to a healthy environment was viewed as a novel, even radical, idea...

Heavy Metal Partitioning in Bottom Sediments of the Matanza-Riachuelo River and Main Tributary Streams

This study provides geochemical partitioning, potential bioavailability, and enrichment of Cd, Cu, Pb, and Zn in bottom sediments collected from the Matanza-Riachuelo River and its main tributary streams. A modified Tessier sequential extraction procedure, complemented with acid volatile sulfide (AVS) and simultaneous extracted metals (SEM) measurements, was applied to determine the partitioning of metals into four fractions (metals bound to amorphous sulfide, carbonate, and exchangeable), bound to Fe/Mn oxides (reducible), bound to organic matter/sulfide (oxidizable) and residual. Spatial and vertical distributions of metals were studied. The core sediments show a decreasing concentration of metals with depth. In top sediments, non-residual Cu was mainly associated with oxidizable phase, whereas Pb, Cd, and Zn were mainly associated with amorphous sulfide. Pb exhibited the highest enrichment in all sites. The ratio AVS/SEM was greater than one at sediment sections close to the water column, indicating that metals extracted with hydrochloric acid were mainly associated with the amorphous sulfide. The strong influence of amorphous sulfide in the retention of Cd, Pb, and Zn in anoxic sediments of Matanza-Riachuelo river system suggests that dredging and aeration could lead to the remobilization of metals from sediments to the water column, hence making the metals more available to the biota.

Genotoxicity of leachates from highly polluted lowland river sediments destined for disposal in landfill

The Matanza-Riachuelo is one of the most polluted rivers of Latin America. The complex chemical mixture of pollutants discharged into the river is accumulated in the river sediments. In this paper, Matanza-Riachuelo river sediment composition and genotoxicity were tested in order to develop a cost-effective, environmentally sound option for disposal and management of contaminated dredged materials. Sampling was performed in a rural area, in a solid waste dumpsite and also in an urban and industrial area. The concentrations of total heavy metals increased from the upper basin to the lower basin. The Ames Salmonella typhimurium test and the Saccharomyces cerevisiae D7 test were performed using toxicity characteristic leachate procedure (TCLP) leachates. The concentrations of copper, lead, and chromium in the leachates exceeded the guide levels for the protection of aquatic life. Low concentrations of organic chlorinated compounds were detected in the leachates. Genotoxic profiles were obtained by testing TCLP leachates from polluted sediment samples with Salmonella typhimurium, Saccharomyces cerevisiae D7, and water sediment suspension with Allium cepa test. No mutagenicity effects on Ames test were observed. Gene conversion and mitotic reversion in Saccharomyces cerevisiae D7 and chromosome aberration in Allium cepa were induced by the sediment samples. Results obtained suggest that dredged sediments could be classified as genotoxic hazardous waste.

Phosphorus distribution in sediments of Morales Stream (tributary of the Matanza-Riachuelo River, Argentina). The influence of organic point source contamination

Increased discharges of organic matter from different sources in Morales Stream, one of the main tributaries of the Matanza-Riachuelo River, caused not only an increase in its primary production but also drastic changes in the composition of its sediments, thus favoring eutrophication processes. An in situ study was carried out in order to assess the effects of an organic point source contamination (from intensive cattle rearing) on the sediments of Morales Stream. Surface water and sediment samples were analysed to determine the chemical characteristics of the water–sediment system. The amounts and forms of sediment phosphorus were determined using the `EDTA method' (Golterman, 1996) at two sites of the stream having different nutrient loads. The increase in the organic load of Morales Stream waters influences the dynamics of sediment P, producing two main effects: (1) an increase in the organic matter amount of the sediment that leads to an increase in the amount of P associated to organic fractions, which may be released by bacterial activity under anoxic conditions; and (2) a decrease in the concentration of P in the fraction bound to iron. Morales Stream sediments may act as a potential source of P, which can release this nutrient to water under the reducing conditions originated by uncontrolled discharges of organic residues to this water body.

Epipelic diatoms from the Matanza-Riachuelo river (Argentina), a highly polluted basin from the pampean plain: biotic indices and multivariate analysis

During the fall and winter of 1995, ninety-two samples were collected from twenty-three sampling stations in the Matanza-Riachuelo river basin. Epipelic diatoms and physico-chemical parameters were studied to establish water quality. Ecological methodologies (species richness, diversity and saprobity indices and multivariate analysis) were employed to assess the impact of the pollution on diatom assemblages. Suspended solids, biological and chemical oxygen demands increased downstream, and dissolved oxygen, pH and transparency increased upstream. Conductivity was variable. This fluvial system is affected by organic and inorganic pollutants, many of them toxic. The presence of heavy metals, phenols, pesticides, hydrocarbons among other chemicals, mostly account for the impoverishment of the diatom assemblages of the basin, thus leading to changes in assemblages structure. Changes in water quality were better reflected by species richness, diversity indices and by principal component analysis than pollution indices in this basin.

Epipelic diatoms from the Matanza-Riachuelo river (Argentina), a highly polluted basin from the pampean plain: biotic indices and multivariate analysis

AbstractDuring the fall and winter of 1995, ninety-two samples were collected from twenty-three sampling stations in the Matanza-Riachuelo river basin. Epipelic diatoms and physico-chemical parameters were studied to establish water quality. Ecological methodologies (species richness, diversity and saprobity indices and multivariate analysis) were employed to assess the impact of the pollution on diatom assemblages. Suspended solids, biological and chemical oxygen demands increased downstream, and dissolved oxygen, pH and transparency increased upstream. Conductivity was variable. This fluvial system is affected by organic and inorganic pollutants, many of them toxic. The presence of heavy metals, phenols, pesticides, hydrocarbons among other chemicals, mostly account for the impoverishment of the diatom assemblages of the basin, thus leading to changes in assemblages structure. Changes in water quality were better reflected by species richness, diversity indices and by principal component analysis than pollution indices in this basin.

Use of epipelic diatoms for evaluation of water quality in the Matanza-Riachuelo (Argentina), a pampean plain river

Epipelic diatom assemblages have been used to evaluate water quality in the Matanza-Riachuelo river basin. Twenty-three sites were sampled in April, May, June and August 1995, before the setup of restoration programs. The Matanza-Riachuelo river basin is located in N.E. Buenos Aires province. It runs across one of the most industrialized and populous zones of Argentina, for which it is subject to strong anthropogenic disturbances. A total number of 97 taxa were identified of which only 37 were abundant. Navicula cryptocephala, Nitzschia palea and N. umbonata occur in the whole basin though more frequent downstream; Stephanodiscus hantzschii and Cyclotella meneghiniana develop where the river becomes wider and deeper. The distribution of the diatomological flora in the Matanza-Riachuelo basin was affected by the increasing concentration of organic matter carried by the river and downstream for the input of chemical compounds, several of which are toxic to aquatic life (i.e. heavy metals, phenols, hydrocarbon, etc.). The assemblage was dominated by pollution-tolerant species, which implies strong to very strong contamination in a great portion of the basin.