Cadmium and chromium removal kinetics from solution by two aquatic macrophytes

The aim of this work was to determine chromium and cadmium bioaccumulation processes of two free-floating macrophytes commonly used in wetlands for water treatment: Salvinia herzogii and Pistia stratiotes. Metal removal from the solution involves two stages: a fast one and a slow one. The fast stage of the Cd uptake is significantly different for each species, while it is not significantly different in Cr uptake. The most important processes of Cd uptake are biological ones in S. herzogii and adsorption, chelation and ionic exchange are in P. stratiotes. The main processes of Cr uptake in both macrophytes are adsorption, chelation and ion exchange. The slow stage is different for each species and metal. Cr precipitation induced by roots occurs in P. stratiotes. Cr uptake through leaves is probably the main cause of the increase of Cr in the aerial parts of S. herzogii.     

The tidal hydrodynamics modeling of the Topolobampo coastal lagoon system and the implications for pollutant dispersion

The tidal hydrodynamics of the Topolobampo coastal lagoon system (Mexico) has been investigated through a modified two dimensional non-linear hydrodynamic finite difference model. The advective and diffusive process acting over a hypothetical pollutant released into the coastal lagoon have also been simulated. Maxima tidal currents (0.85 m/s) were predicted within the main channel, in agree with direct measurements. The direction of the observed fastest currents (SW), also agree quite well with the direction of the strongest tidal current predicted in this investigation, which occur during the ebb when the water of the coastal lagoon is discharged into the Gulf of California. Residual currents (0.01-0.05 m/s) were also predicted. The hypothetical pollutant released within the Topolobampo Harbor would spread to both Ohuira and Topolobampo sections, reaching the inlet after approximately 12 days.     

Cephalopods and cetaceans as indicators of offshore bioavailability of cadmium off Central South Brazil Bight

Regarding Brazilian coast, industrial and urban developments are concentrated along Central South Brazil Bight. Samples from inshore and offshore species from the concerned area were analyzed, comprising 24 cetaceans (9 species) and 32 squids (2 species). Cadmium was determined by GFAAS and our results were in agreement with certified values (DOLT-2, NRCC). Mean cadmium concentration (in microg/g, wet weight) observed in the digestive gland of sexually mature Argentine short-finned squids (Illex argentinus) was 1002.9. To our knowledge this is the highest cadmium level ever reported for a cephalopod. Concerning cetaceans, our results include one of the highest renal cadmium concentrations described for striped dolphins (71.29 microg/g, wet weight). Anthropogenic action, upwelling and cannibalism of Argentine short-finned squid on the studied area are possible reasons for such remarkable cadmium concentrations.     

Virological Characterization of Roof-Harvested Rainwater of Densely Urbanized Low-Income Region

Food and Environmental Virology - Roof-harvested rainwater (RHRW) is considered relatively clean water, even though the possible presence of pathogens in the water may pose human health risks. In...     

Extraction wells and biogas recovery modeling in sanitary landfills

A general methodology is established that permits the characterization and evaluation of the optimum potential of biogas extraction at each vertical well in the sanitary landfill of Asturias, Spain. Twenty wells were chosen from a total of 225 for the study, and the maximum production flow of biogas, which is a result of the degradation of the municipal solid waste deposited within its area of influence, was determined for each well. It was found that this flow varied with time and is characteristic of each extraction well. The maximum extractable flow also was determined as a function of the composition of the biogas needed for its subsequent utilization. The biogas extraction yield in the wells under study varied between approximately 26 and 97%, with a mean recovery value of 82%. The low yields found in certain cases were generally caused by a sealing defect, which leads to excessive incorporation of air into the landfill gas through the surrounding soil or through the extraction shaft, and which make its subsequent utilization difficult.     

Pressurised liquid-liquid extraction. An approach to the removal of inorganic non-metal species from used industrial oils

Modified pressurised hot water is used for the development of a high pressure liquid-liquid extraction method for the decontamination of used industrial oils from inorganic non-metal species (chlorine, fluorine and sulphur). The oils were subjected to dynamic extraction with water modified with 5% v/v HNO3 at 200 degrees C as extractant. Under these working conditions the analytes were transferred to the aqueous phase. Spontaneous separation of the two immiscible liquid phases (the used oil and extract) takes place in the collection flask after extraction. The treated and untreated oil samples were oxidised and the chloride, fluoride and sulphate thus formed were determined by ion-chromatography. The method was applied to four oil samples from different locations in Spain. A residence time of approximately =10 min provided oil samples from which 88.3%, 89.4% and 89.4% of chloride, fluoride and sulphate, respectively, have been removed with respect to the initial concentration of each analyte in the oil. The repeatability, expressed as relative standard deviation (RSD), was of 11.9%, 13.7% and 7.2% for Cl(-), F(-) and SO4(2-), respectively; whilst the within-laboratory reproducibility yielded RSDs of 6.2%, 7.9% and 6.2% for the same analytes. The proposed approach has proved to be efficient, simple, easily transferable to industrial scale, cheap, fast and environmentally friendly.     

Carbon storage in Amazonia during the last glacial maximum: secondary data and uncertainties

The Amazonian forest is, due to its great size, carbon storage capacity and present-day variability in carbon uptake and release, an important component of the global carbon cycle. Paleo-environmental reconstruction is difficult for Amazonia due to the scarcity of primary palynological data and the mis-interpretation of some secondary data. Studies of lacustrine sediment records have shown that Amazonia has known periods in which the climate was drier than it is today. However, not all geomorphological features such as dunes, and slope erosion, which are thought to indicate rainforest regression, date from the time of the Late Glacial Maximum (LGM) and these features do not necessarily correspond to episodes of forest regression. There is also uncertainty concerning LGM carbon storage due to rainforest soils and biomass estimates. Soil carbon content may decrease moderately during the LGM, whereas rainforest biomass may change considerably in response to changes in the global environment. Biomass per unit area in Amazonia has probably been reduced by the cumulative effects of low CO2 concentration, a drier climate and lower temperatures. As few paleo-vegetation data are available, there is considerable uncertainty concerning the amount of carbon stored in Amazonia during the LGM, which may have corresponded to 44-94% of the carbon currently stored in biomass and soils.     

Motivations for Adopting the ISO 14001 Standard: A Study of Spanish Industrial Companies

This article analyzes what motivates companies to obtain ISO 14001 certification and what factors within companies determine the success or failure of the environmental management standard. The most important motivators appear to be the worldwide recognition accorded the ISO 14000 norm, and its applicability to all sectors. The factors that most contribute to success are the company's experience in management systems and involvement by management. Failure most often results from lack of employee training and organizational rigidity. © 2001 John Wiley & Sons, Inc.     

UVR-induced photoinhibition of summer marine phytoplankton communities from Patagonia

During austral summer 2006, experiments were carried out to evaluate the effects of ultraviolet radiation (UVR, 280–400 nm) on carbon fixation of natural phytoplankton assemblages from Patagonia (Argentina). Surface water samples were collected (ca. 100 m offshore) at mid morning using an acid-cleaned (1 N HCl) dark container. The short-term impact of UVR (measured as radiocarbon incorporation) was immediately assessed by exposing samples to three artificial illumination treatments: PAR (400–700 nm), PAR + UV-A (320–700 nm), and PAR + UV-A + UV-B (280–700 nm). Pico-nanoplankton characterized the assemblages, and taxon-specific pigment fingerprinting combined with CHEMTAX and supplemented with microscopic observations showed varied proportions of diatoms, chlorophytes, and cyanobacteria throughout January–February 2006. Photosynthetic efficiency, as assessed through assimilation numbers, was high [between 4.4 and 10.4 μg C (μg chl-a)⁻¹ h⁻¹], and it was probably favored by the supply of inorganic nutrients from the Chubut River. UVR-induced photoinhibition appeared to be related to the taxonomic composition: in general, higher photoinhibition was observed when diatoms dominated, whereas this was lower when samples were dominated by chlorophytes. Our data suggest that xanthophyll pigments might have provided only limited protection in these already highlighted acclimated assemblages.