RESUMO
This work provides a preliminary study of the destination, mobility, and availability of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in contaminated sediments and water column within Puerto Rosales Port, located in the middle zone of the Bahía Blanca Estuary (Argentina). Therefore, this study presents the first comprehensive results of the role of several physicochemical parameters (temperature, pH, Eh, salinity, turbidity, organic matter, chlorophyll, and macronutrients) in behavior of organotin compounds (OTCs) in a marine-coastal ecosystem. The samples were collected seasonally in May, August, and November during 2014. Levels of OTCs were determined in sediments and water column samples by means of gas chromatography-mass spectrometry analysis. Degradation index analyses suggested not recent inputs of TBT at the area of study. However, results submitted a continuous input of TBT into the column water; further, its distribution and degradation pattern were shown to be influenced by salinity, turbidity, particulate organic matter, chlorophyll, and nitrates. These last two parameters, chlorophyll and nitrates, also were very important for sediment samples. Chlorophyll together with high temperatures recorded in the surface sediments triggers biodegradation process of TBT and DBT resulting in high MBT levels while nitrates seemed to promote debutylation process. Furthermore, pH appeared to influence drastically the adsorption/desorption activity of TBT and DBT in sediment. Finally, the Eh obtained suggested a degradation of TBT thanks to the presence of Fe (III) in this compartment. In addition, in fact, the results outlined a possible MBT additional input that contributes to the pollution observed in the study area. Graphical abstract Organotin compounds behavior according to several physicochemical parameters.
Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Compostos Orgânicos de Estanho/análise , Compostos de Trialquitina/análise , Poluentes Químicos da Água/análise , Argentina , Biodegradação Ambiental , Brasil , Clorofila/análise , Estuários , Cromatografia Gasosa-Espectrometria de Massas , Nitratos/análiseRESUMO
Magnetic nanoparticles (MNPs), based on iron oxide (magnetite) and ferrogel of gelatin and MNPs, were employed as efficient tools for the removal of heavy metals and nutrients from water samples from Bahia Blanca estuarine (BBE). An exhaustive adsorption performance of Cu, NO3-, and NO2- was conducted in batch using model solutions aiming to adjust the adsorption conditions. Adsorption studies using water simulating the real samples were also performed. Both kinds of nanomaterials demonstrated an efficiency between 60 and 80%, and 85% for the removal of heavy metals and NO3- and NO2-, respectively. Similar adsorption assays were performed using BBE water samples, employing the experimental conditions explored with model and simulated water. The reached efficiency was 30 and 45% for heavy metal and nutrient removal, respectively, using nanoparticles; meanwhile, ferrogels displayed a removal capacity around 50-60%. The nanoparticles showed structural instability by the leaching of iron to the medium after the adsorption processes. Ferrogels remained almost inalterable in terms of their integrity during the adsorption time. These materials showed satisfactory perspectives regarding their reuse possibilities. They were used for almost five repeated cycles of adsorption without losing efficiency on the adsorption. The results of this study suggest that MNPs and FGs appear as versatile and promising materials that may be considered as valid alternatives to the actual tools for the remediation of real water samples.
Assuntos
Gelatina/química , Nanopartículas de Magnetita/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Géis , Ferro/química , Fenômenos Magnéticos , Metais Pesados/química , Nanotecnologia , Nitratos/química , Nitritos/químicaRESUMO
Four sites were selected in a salt marsh in the Bahia Blanca Estuary (Argentina): (1) low marsh (flooded by the tide twice daily) vegetated by S. alterniflora; (2) non-vegetated low marsh; (3) high marsh (flooded only in spring tides) vegetated by S. alterniflora; (4) non-vegetated high marsh. The pH and Eh were measured in sediments, while dissolved nutrients (ammonium, nitrate, nitrite and phosphate) and particulate organic matter (POM) were determined in pore water. pH (6.2-8.7) was only affected by vegetation in low areas. Eh (from -300 to 250 mV) was lower at low sites than at high ones; in the latter, the values were higher in the non-vegetated sediments. The POM concentration was greater in the high marsh than in the low marsh, with no effect of vegetation. Ammonium was the most abundant nitrogen nutrient species in pore water, except in the non-vegetated high marsh where nitrate concentration was higher. All nitrogen nutrients were affected by both flooding and vegetation. Phosphate was always present in pore water at all sites throughout the year and its concentration varied within narrow limits, with no effect of flooding and greater values always at non-vegetated sites. Our results showed that the variability of the pore water composition within the marsh is greater than the temporal variation, meaning that both tidal flooding and vegetation are important in the dynamics of nutrients and organic matter in the sediment pore water.
Assuntos
Carbono/análise , Inundações , Nitrogênio/análise , Fósforo/análise , Plantas , Poaceae , Água do Mar/química , Sedimentos Geológicos , Concentração de Íons de HidrogênioRESUMO
The study deals with the determination of physico-chemical parameters, inorganic nutrients, particulate organic matter, and photosynthetic pigments on a monthly basis during an annual cycle from nine sampling sites of the coastal zone of a high-latitude ecosystem (Tierra del Fuego, Argentina). Nitrites and phosphates concentrations were similar to other systems of the south Atlantic coast (median, 0.30 and 1.02 µM, respectively), while nitrates were higher in all sampling periods (median, 45.37 µM), and silicates were significantly smaller (median, 7.76 µM). Chlorophyll a and phaeopigments have shown median values of 0.38 and 0.85 mg m(-3), respectively, while saturated values of dissolved oxygen were recorded throughout the study. The analysis reflected that nutrient enrichment seems to be linked to an anthropogenic source, the presence of peatlands areas, and a sink of Nothofagus pumilio woods. The area could be characterized in three zones related to (1) high urban influence, (2) natural inputs of freshwater, and (3) mixed inputs coming from moderate urban impacts.