RESUMEN
The aim of this work was to study the efficiency of microcosms-scale floating treatment wetlands (FTWs) in the N and P removal from a synthetic runoff effluent and to evaluate the effluent tolerance of Typha domingensis. Each FTW consisted of a raft constructed with a plastic net where T. domingensis plants were installed. In order to evaluate the plant role, reactors with FTWs and without FTWs (controls) were used. P and N additions were carried out as follows: 5â¯mgâ¯L-1 P (P5 and P5-control); 10â¯mgâ¯L-1â¯N (N10 and N10-control); 5â¯mgâ¯L-1 Pâ¯+â¯10â¯mgâ¯L-1â¯N (P5N10 and P5N10-control). Also, a biological control (B-control) without contaminant addition was used. The removal of soluble reactive phosphorus and total phosphorus were significantly higher in the FTWs than in the controls. Ammonium and nitrate concentrations were not significantly different between FTWs and controls at the end of the experiment. However, nitrate concentrations showed significant differences between FTWs and controls during the experiment. N and P were mainly accumulated in plant tissues and not in the sediment. Plants tolerated the effluent conditions and showed a positive growth rate. The use of FTWs is a promising strategy for the sustainable treatment of water bodies affected by runoff waters.
Asunto(s)
Nitrógeno/análisis , Fósforo/análisis , Typhaceae/metabolismo , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/análisis , Biodegradación Ambiental , HumedalesRESUMEN
A free water surface constructed wetland (CW) designed for effluent treatment was dominated by the emergent macrophyte Typha domingensis reaching a cover of roughly 80% for 5 years. Highly efficient metal and nutrient removal was reported during this period. In June 2009, a population of approximately 30 capybaras (Hydrochoerus hydrochaeris) caused the complete depredation of the aerial parts of macrophytes. However, plant roots and rhizomes were not damaged. After depredation stopped, T. domingensis showed a luxuriant growth, reaching a cover of 60% in 30 days. The objective of this work was to evaluate the sustainability of the CW subjected to an extreme event. Removal efficiency of the system was compared during normal operation, during the depredation event and over the subsequent recovery period. The CW efficiently retained contaminants during all the periods studied. However, the best efficiencies were registered during the normal operation period. There were no significant differences between the performances of the CW over the last two periods, except for BOD. The mean removal percentages during normal operation/depredation event/recovery period, were: 84.9/73.2/74.7% Cr; 66.7/48.0/51.2% Ni; 97.2/91.0/89.4% Fe; 50.0/46.8/49.5% Zn; 81.0/84.0/80.4% NO3(-); 98.4/93.4/84.1% NO2(-); 73.9/28.2/53.2% BOD and 75.4/40.9/44.6% COD. SRP and TP presented low removal efficiencies. Despite the anoxic conditions, contaminants were not released from sediment, accumulating in fractions that proved to be stable faced with changes in the operating conditions of the CW. T. domingensis showed an excellent growth response, consequently the period without aerial parts lasted a few months and the CW could recover its normal operation. Plants continued retaining contaminants in their roots and the sediment increased its retention capacity, balancing the operating capacity of the system. This was probably due to the fact that the CW had reached its maturity, with a complete root-rhizome development. These results demonstrated that faced with an incidental problem, this mature CW was capable of maintaining its efficiency and recovering its vegetation, demonstrating the robustness of these treatment systems.
Asunto(s)
Typhaceae/crecimiento & desarrollo , Eliminación de Residuos Líquidos/métodos , Humedales , Animales , Argentina , Biodegradación Ambiental , Análisis de la Demanda Biológica de Oxígeno , Sedimentos Geológicos , Metales/metabolismo , Nitratos/metabolismo , Fósforo/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Roedores , Contaminantes Químicos del Agua/metabolismoRESUMEN
The aim of this work was to study the accumulation and fractionation of P in the inlet and outlet sediment of a constructed wetland for the wastewater treatment of a metallurgic plant in Argentina. It was important to predict whether P could be released into the water again by changing environmental conditions or retained over time. P-fractionation was performed using a sequential extraction method. Sediment cores were sliced at depths of: 0-3; 3-7 and 7-10 cm. Sediment showed high pH values and anoxic conditions. In the inlet area, P was principally bound to the carbonate fraction, whereas in the outlet area, it was mainly bound in the residual fraction. This behavior was justified by the effluent composition, which is rich in Ca2+ and Fe3+ and presents high values of pH and conductivity. These conditions favor CaCO3 and Fe(OOH)n precipitation and the subsequent sorption of P to their surface. The sediment active layer involved in the exchange reactions was the superficial one (0-3 cm). The wetland is highly efficient in P retention. P was retained by sediment in fractions that will not release it to the water while chemical and environmental conditions of the system are maintained.
Asunto(s)
Sedimentos Geológicos/análisis , Fósforo/análisis , Administración de Residuos , Humedales , Residuos Industriales , MetalurgiaRESUMEN
The aim of this work was to assess the uptake efficiencies, the uptake and bioaccumulation kinetics and the toxic effects of Cr, Ni and Zn on Eichhornia crassipes. Plants were exposed to 1 mg L(-1) of each metal and sampled during 30 days. E. crassipes removed 81%, 95% and 70% of Cr, Ni and Zn, respectively. Metal removal from water involved a fast and a slow component. Metals were accumulated fundamentally by roots. Cr was scarcely translocated to aerial parts. In these tissues, Ni showed the highest accumulation amount while Zn presented the highest accumulation rate. Metal toxicity on the biomass was different among treatments. However, biomass did not decrease in any case. All the studied metals produced chlorophyll decrease. The root cross-sectional area (CSA) and vessel number increased and the root length decreased when plants were exposed to Zn. Despite the toxic effects, E. crassipes accumulated Cr, Ni and Zn efficiently.
Asunto(s)
Eichhornia/efectos de los fármacos , Metales Pesados/farmacología , Raíces de Plantas/metabolismo , Clorofila/biosíntesis , Cromo/farmacología , Eichhornia/crecimiento & desarrollo , Cinética , Metales Pesados/farmacocinética , Níquel/farmacología , Raíces de Plantas/efectos de los fármacos , Zinc/farmacologíaRESUMEN
The aim of this work was to compare the adaptability of two different populations of Typha domingensis exposed to high pH and salinity. The plants were sampled from an uncontaminated natural wetland (NW) and a constructed wetland (CW) for the treatment of an industrial effluent with high pH and salinity. The plants from each population were exposed to the following combined treatments of salinity (mg l(-1)) and pH: 8,000/10 (values found in the CW); 8,000/7; 200/10 and 200/7 (typical values found in the NW). Chlorophyll concentration, relative growth rates (RGR) and root structure parameters (cross-sectional areas of root, stele and metaxylem vessels) were measured. Images of roots and leaves by scanning electronic microscopy (SEM) were obtained, and X-ray microanalysis in different tissues was carried out. In all treatments, the RGR and chlorophyll increase were significantly lower in the plants from the NW than in the plants from the CW. However, stress was observed when the plants from the CW were exposed to treatment 200/7. In treatment 8,000/10 the tissues of the plants from the NW showed severe damages. The root structure of plants from the CW was modified by salinity, while pH did not produce changes. In plants from the CW there were no differences between Na concentration in leaves of the treatments 8,000/10 and 200/7, indicating that Na was not transported to leaves. The CW population already possesses physiological and morphological adaptations due to the extreme conditions of pH and salinity. Because of its adaptive capacity, T. domingensis is an efficient species to treat wastewater of high pH and salinity.
Asunto(s)
Adaptación Fisiológica , Typhaceae/fisiología , Biodegradación Ambiental , Clorofila/metabolismo , Agua Dulce/química , Concentración de Iones de Hidrógeno , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Raíces de Plantas/fisiología , Salinidad , Typhaceae/crecimiento & desarrollo , Typhaceae/metabolismo , HumedalesRESUMEN
Typha domingensis had become the dominant species after 2 years of operation of a wetland constructed for metallurgical effluent treatment. Therefore, the main purpose of this study was to investigate its ability to tolerate the effluent and to maintain the contaminant removal efficiency of the constructed wetland. Plant, sediment, and water at the inlet and outlet of the constructed wetland and in two natural wetlands were sampled. Metal concentration (Cr, Ni, and Zn) and total phosphorus were significantly higher in tissues of plants growing at the inlet in comparison with those from the outlet and natural wetlands. Even though the chlorophyll concentration was sensitive to effluent toxicity, biomass and plant height at the inlet and outlet were significantly higher than those in the natural wetlands. The highest root and stele cross-sectional areas, number of vessels, and biomass registered in inlet plants promoted the uptake, transport, and accumulation of contaminants in tissues. The modifications recorded accounted for the adaptability of T. domingensis to the conditions prevailing in the constructed wetland, which allowed this plant to become the dominant species and enabled the wetland to maintain a high contaminant retention capacity.
Asunto(s)
Residuos Industriales , Metales Pesados/toxicidad , Typhaceae/efectos de los fármacos , Eliminación de Residuos Líquidos , Contaminantes Químicos del Agua/toxicidad , Humedales , Typhaceae/anatomía & histologíaRESUMEN
Proximal femoral focal deficiency is a rare skeletal disorder, with an estimated incidence of 0.11 to 0.2/10,000 births. The bilateral form is uncommon, occurring in 10 to 15% of cases. We report a case of bilateral proximal femoral focal deficiency diagnosed by ultrasound at 30 weeks' gestation. Differential diagnosis, prognosis and management are discussed.