Growth, accumulation and uptake of Eichhornia crassipes exposed to high cadmium concentrations.

A greenhouse experiment was performed to evaluate the growth, accumulation, and uptake rate of Eichhornia crassipes subject to high cadmium concentrations. Three doses of Cd were added to polluted river water (1, 5, and 10 mg Cd/L), and polluted water with basal Cd concentration (0.070 mg/L) was used as a control. The experiment lasted for 7 days. Signs of stress and toxicity were visible in all treatments from day 3 of the experiment. The growth of the water hyacinth was slightly stimulated in the presence of low Cd concentration (1 mg/L), but this could also be due to the chloride and other nutrients present in the polluted water. Cd was accumulated mainly in roots, showing a maximum concentration of 1742.1 mg Cd/kg dw (10 mg Cd/L). The translocation from roots to leaves was low, with a maximum accumulation of 147.4 mg Cd/kg dw (10 mg Cd/L). The uptake rate for roots reached a maximum of 248.7 mg Cd/kg·day while the uptake rate for leaves did not saturate in the range of the studied concentrations (max. 20.8 mg Cd/kg·day). The water hyacinth showed promising results for the application in the treatment of Cd-polluted waters given its ability to tolerate high Cd concentrations in the media (up to 10 mg Cd/L) and its capacity for uptake and accumulation.

Sewage pollution: genotoxicity assessment and phytoremediation of nutrients excess with Hydrocotyle ranunculoides.

The discharge of sewage effluents into low-order streams has negative effects on water quality. Macrophytes can be efficient in the treatment of this wastewater due to the removal of the main pollutants. The genotoxicity of sewage-polluted water discharging into La Choza stream was evaluated by testing with Allium cepa. Also, a phytoremediation assay with continuous recirculation of the residual water was conducted for 12 days. Three treatments were carried out. One treatment (Hr) was performed with a macrophyte (Hydrocotyle ranunculoides), and two treatments were conducted without macrophytes: with lighting (Ai) and without lighting (Ao). The wastewater was toxic according to all the evaluated indexes (mitotic index, frequency of chromosomal aberrations and micronucleus). High concentrations of ammonium, dissolved inorganic nitrogen (DIN), total (TP) and soluble reactive phosphorous (SRP) and indicators of faecal contamination were determined in the wastewater. The ammonium, DIN, SRP and TP loads at the end of the assay were significantly lower in the treatments with light (Hr and Ai). So, the nutrient removal was due to their absorption and adsorption by the periphyton and H. ranunculoides. Our results lead us to recommend the maintenance and planting of macrophytes in lowland streams subject to sewage pollution.

Copper uptake by Eichhornia crassipes exposed at high level concentrations.

The objective of this study was to assess the growth of water hyacinth (Eichhornia crassipes) and its ability to accumulate Cu from polluted water with high Cu concentrations and a mixture of other contaminants under short-term exposure, in order to use this species for the remediation of highly contaminated sites. Two hydroponic experiments were performed under greenhouse conditions for 7 days. One of them consisted of growing water hyacinth in Hoagland solution supplemented with 15 or 25 mg Cu/L and a control. The other one contained water hyacinth growing in polluted river water supplemented with 15 mg Cu/L and a control. Cu was accumulated principally in roots. The maximum Cu concentration was 23,387.2 mg/kg dw in the treatment of 25 mg Cu/L in Hoagland solution. Cu translocation from roots to leaves was low. The mixture of 15 mg Cu/L with polluted water did not appear to have toxic effects on the water hyacinth. This plant showed a remarkable uptake capacity under elevated Cu concentrations in a mixture of pollutants similar to pure industrial effluents in a short time of exposure. This result has not been reported before, to our knowledge. This species is suitable for phytoremediation of waters subject to discharge of mixed industrial effluents containing elevated Cu concentrations (≥15 mg Cu/L), as well as nutrient-rich domestic wastewaters.

Impacts of composite wastewater on a Pampean stream (Argentina) and phytoremediation alternative with Spirodela intermedia Koch (Lemnaceae) growing in batch reactors.

Poultry slaughterhouses are producing increasing amounts of solid organic by-products and waste in Argentina. The objectives of this study are to assess the impacts of wastewater, mainly composed of poultry slaughterhouse effluent, on a Pampean stream and to evaluate the convenience of phytoremediation alternative with Spirodela intermedia. Impacts over La Choza stream (Buenos Aires, Argentina) were evaluated by means of physical and chemical characterization of the water upstream and downstream input. Nutrients and total suspended solids increased downstream of the open channel outlet. A bioassay was performed in order to evaluate the role of S. intermedia in wastewater treatment. Two treatments were performed in batch reactors during 144 h (6 days), with (treatment A) and without (treatment B) the addition of S. intermedia. Water samples were taken at 8, 24, 48, 96 and 144 h after the start of the assay for the determination of ammonium, nitrite, nitrate, soluble reactive phosphorus and total phosphorus. Since removal rates of ammonium and total phosphorus were significantly higher in treatment A than in treatment B and the nitrification process was highly increased in treatment A, then the species could be used for the phytoremediation of composite wastewater.

Performance of pilot-scale constructed wetlands for secondary treatment of chromium-bearing tannery wastewaters.

Tannery operations consist of converting raw animal skins into leather through a series of complex water- and chemically-intensive batch processes. Even when conventional primary treatment is supplemented with chemicals, the wastewater requires some form of biological treatment to enable the safe disposal to the natural environment. Thus, there is a need for the adoption of low cost, reliable, and easy-to-operate alternative secondary treatment processes. This paper reports the findings of two pilot-scale wetlands for the secondary treatment of primary effluents from a full tannery operation in terms of resilience (i.e., ability to produce consistent effluent quality in spite of variable influent loads) and reliability (i.e., ability to cope with sporadic shock loads) when treating this hazardous effluent. Areal mass removal rates of 77.1 g COD/m2/d, 11 g TSS/m2/d, and 53 mg Cr/m2/d were achieved with a simple gravity-flow horizontal subsurface flow unit operating at hydraulic loading rates of as much as 10 cm/d. Based on the findings, a full-scale wetland was sized to treat all the effluent from the tannery requiring 68% more land than would have been assumed based on literature values. Constructed wetlands can offer treatment plant resilience for minimum operational input and reliable effluent quality when biologically treating primary effluents from tannery operations.

Use of tree bark for comparing environmental pollution in different sites from Buenos Aires and Montevideo.

Multi-elemental profiles in bark of green ash trees collected in three representative areas of Buenos Aires, Argentina and Montevideo, Uruguay, were assessed as potential air pollution indicators. Ten elements: Al, Ba, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn, were measured using inductively coupled plasma optical emissions spectrometry from 70 samples collected in different environments: central, residential and rural (reference site), in order to compare spatial patterns of metal concentration. The samples used as a control were collected from a nature reserve situated far away from any significant influences, not even a nearby road. The reference site (RF) exhibited the lowest concentrations of Al, Cr, Fe, Ni, Pb, and Zn. However, Ba and Mn showed similar concentrations in all measured sites. Magnesium is the only element that had a greater concentration in RF than at the other sites. Copper did not show any clear pattern. The Centre of Montevideo (MVD) showed higher concentrations of Al, Ba, Cr, Fe, Pb and Zn than the Centre of Buenos Aires (BA). In the A sectors, Montevideo (SAMVD) showed higher concentrations of Al, Cu, Mg, Ni, and Zn and lower concentrations of Ba, Cr, Fe, Mn, and Pb than Buenos Aires (SABA). In the B sectors, Montevideo (SBMVD) showed higher concentrations of Al, Ba, Cu, Fe, Pb, and Zn and lower concentrations of Cr and Mg than Buenos Aires (SBBA), but similar concentrations of Mn and Ni. The use of bark for biomonitoring metals allowed us to detect concentration differences related to the urban fabric and the different kinds of vehicles and their fuels. In the cities, the differences in metal concentrations detected in bark were more striking between the sectors than between centers, despite CBA being much larger than CMVD in population, extension and vehicular traffic.

Sedimentación atmosférica seca en hojas de Morus alba L: En la ciudad de San Juan, Argentina / Dry atmospheric deposition on Morus alba L. Leaves in San Juan city, Argentina / Sedimentação atmosférica seca em folhas de Morus alba L. Na cidade de San Juan, Argentina

Durante un ciclo vegetativo completo, que comprende tres periodos de muestreos: primavera, verano y fin de otoño, en hojas de Morus alba de la ciudad de San Juan, Argentina, se analizó la variación en la deposición del particulado en suspensión y de algunos componentes químicos. Los análisis fueron realizados en hojas de 40 árboles seleccionados al azar, 20 en el área urbana y 20 en la suburbana. En el material seco obtenido, se determinó los contenidos de K, Ni, Cd, Pb y Fe. Se analizó estadísticamente la relación funcional entre la biomasa y el área foliar, estableciéndose la ecuación de regresión que expresa la relación entre ambas variables. Para las comparaciones, considerando urbano y suburbano, se empleó el test de Tuckey. La áreas foliares no difieren estadísticamente entre las localidades. El área foliar externa media representa el 52,1 ±13,4% en el urbano y el 55,2 ±9,2% en el suburbano. Los datos obtenidos se analizaron estadísticamente mediante el test de ANAVA/MANAVA. El particulado acumulado por cm² de follaje en las diferentes estaciones, considerando la ubicación: urbano y suburbano, no difieren estadísticamente. La tasa media de deposición diaria fue de 0,5ppm/cm²/día.

During a complete vegetative cycle, which comprises three sampling periods (spring, summer and end of autumn (previous fall of leaves), the variation in air particle deposition on Morus alba leaves and of some chemical elements was analyzed in San Juan, Argentina. Analyses were performed in leaves from 40 randomly selected trees, 20 in urban and 20 in suburban areas. The contents of K, Ni, Cd, Pb and Fe were determined on dry material. The functional relation between biomass and foliar area was statistically analyzed, finding the regression equation that expresses the relation between both variables. For comparisons, depending on urban and suburban location, the Tuckey test was used. Foliar areas did not differ statistically between locations. The treetop mean external foliar area represents 52.1 ±13.4% in urban and 55.2 ±9.2% in suburban areas. Data obtained were statistically analyzed using the ANOVA/MANOVA test. Accumulated particles by cm² of foliage at different seasons, considering urban and suburban locations, did not differ statistically. Mean daily deposition rate was of 0.5ppm/cm²/day.

Durante um ciclo vegetativo completo, que compreende três periodos de amostragem: primavera, verão e fim de outono, em folhas de Morus alba da cidade de San Juan, Argentina, se analisou a variação na deposição do particulado em suspensão e de alguns componentes químicos. As análises foram realizadas em folhas de 40 árvores selecionadas aleatoriamente, 20 na área urbana e 20 na suburbana. No material seco obtido, se determinaram os conteúdos de K, Ni, Cd, Pb e Fe. Analisou-se estatisticamente a relação funcional entre a biomassa e a área foliar, estabelecendo-se a equação de regressão que expressa a relação entre ambas variáveis. Para as comparações, considerando urbano e suburbano, se empregou o teste de Tuckey. As áreas foliares não diferem estatisticamente entre as localidades. A área foliar externa média representa 52,1 ±13,4% no urbano e 55,2 ±9,2% no suburbano. Os dados obtidos se analisaram estatisticamente mediante o teste de ANAVA/MANAVA. O particulado acumulado por cm² de folhagem nas diferentes estações, considerando a localização: urbano e suburbano, não diferem estatisticamente. A taxa média de deposição diária foi de 0,5ppm/cm²/dia.