Estudios de biodisponibilidad y ecotoxicidad de Cromo en matrices...
This work was done in the Municipality of Belén - Department of Nariño - Colombia, a sector\nwhere 44 tanneries operate, making the tanning industry the main economic activity in this\nregion. In this area, these industries are characterized by the low level of technology in their\nprocesses, the hi...
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| Formato: | Tesis doctoral acceptedVersion |
| Lenguaje: | Español |
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Universidad de Buenos Aires. Facultad de Ciencias Veterinarias
2023
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| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_7204 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_7204.dir/7204.PDF |
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| Sumario: | This work was done in the Municipality of Belén - Department of Nariño - Colombia, a sector\nwhere 44 tanneries operate, making the tanning industry the main economic activity in this\nregion. In this area, these industries are characterized by the low level of technology in their\nprocesses, the high load of chemical substances present in their effluents, and the absence of\nwaste treatment processes. The effluents resulting from the tanning process in Belén are\ndischarged into the Mocondino stream, a small stream that crosses the city. therefore, the\ngeneral objective of this work was established to determine the bioavailability and toxic effects\nof Chromium (Cr) in the Mocondino stream, Department of Nariño, through the design and\nvalidation of a toxicity evaluation model, which allows predicting the effects of Cr under\ncertain conditions of the water column.\nInitially, in order to quantify the chemical substances generated in each stage of the tanning\nprocess and to measure the relationship that exists between the products discharged into the\ntributary and the Cr levels found in the environmental matrices, specific samples of effluents\nfrom four processes were collected: soaking, unhairing, deliming and tanning. It was found that\nthe physicochemical parameters determined in all stages exceeded the values allowed by\nColombian environmental legislation for the punctual discharge of wastewater to surface water\nbodies. It was found that the industries with the lowest production discharged effluents with\nhigher concentrations of total Cr. In the case of solid waste, the leather shavings were\ncharacterized, where a Cr concentration higher than the maximum levels considered by\nenvironmental legislation for the disposal of these wastes was found.\nWith the purpose of studying the mobility of Cr between the environmental matrices, the levels\nof metal in the water, soil, sediment and biota matrices were quantified throughout six sampling\nstations: the first two corresponding to the sector upstream of the discharge of effluents; stations\nIII and IV coinciding with the discharge points and stations V and VI located downstream of\nthe discharges. In the first two stations, no Cr levels were detected in any of the analyzed\nmatrices. From station III, traces of the metal were found in all the matrices studied, with the\nhighest Cr levels coinciding with the proximity to the effluent discharge points. In the last two\nstations, the metal levels decreased significantly. The comparison of Cr levels between\nmatrices made it evident that there is transfer from the water to the other matrices studied, with\nsediments being the matrix where the highest Cr levels were found, confirming the transfer of\nmetal from the aqueous system. Of the Cr levels determined in the matrices, only in the water\ndid they exceed the maximum admissible values. Regarding metal speciation, it was found that in all environmental compartments the dominant species was Cr (III).\nTo determine the phytotoxic effects of the matrices with Cr content, acute toxicity tests were carried out in the Lactuca sativa and Brachiaria humídicola models. Using water from the Mocondino stream and the effluent from the tanning process as a culture medium, the percentage of inhibition in root growth was quantified. With the soil and sediment from the effluent discharge areas, the percentage of inhibition in biomass production was determined.\nHigher percentages of inhibition were found with the effluent as a growth medium. The\npercentages of inhibition in biomass production, found at the effluent discharge point, for the\nsoil and sediment matrices, are higher than expected for the Cr concentrations at that point.\nIn order to determine the most influential physicochemical parameters in the availability of Cr\nand therefore in its toxicity, acute toxicity tests in water were designed, determining mortality \nin three organisms: Daphnia magna, Oreochromis sp (Red Tilapia) and Myleus pacu. (Pacú),\na factorial experimental design, with 5 variables: pH, Hardness, Dissolved Organic Carbon\n(COD), Cr (VI) and Cr (III), with two levels for the first three variables and two levels for the\nvariables Cr (VI) and Cr (III). The results obtained were analyzed through the use of general\nlinearized models, finding higher mortalities associated with high concentrations of Cr (VI)\nand low concentrations of COD and hardness. The comparison of the results obtained with the\norganisms used, indicated that the Daphnia and Tilapia models presented similar behaviors,\nwith high sensitivity to metal. The Pacú model presented higher mortalities than those\npresented with Daphnia and Tilapia.\nConsidering the Pacú model as the most consistent among the organisms studied, it was used,\nunder the Biotic Ligand Model (BLM) approach, to estimate the Cr concentration in the\ndischarged effluents that could cause lethal and sublethal effects under the conditions of the\nwater column in the Mocondino creek. The model showed as a result that Cr levels in the\neffluent much higher than what is established by environmental regulations, in the order of\nbetween 20 and 35 mg/L of Cr, could cause a mortality rate between 25 and 30%.\n\nThe application of the BLM in this study is a contribution that allows estimating the\nbioavailability and toxicity of Cr introduced into the area through effluent discharges from\ntanning industries, in order to properly manage resources to minimize the impacts produced on\nhealth. human and environmental. |
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