Evaluation of metals in several varieties of sweet potatoes (Ipomoea batatas L.): comparative study

Sweet potatoes are a staple in the diet of some people and an excellent source of minerals. Metal monitoring in food, like sweet potatoes, provides basic information on safety aspects in regulatory processes as well as nutritional values. One hundred five samples of three varieties of sweet potatoes were randomly obtained from supermarkets, farmers markets, and farmers' plots in Tenerife (Canary Islands, Spain). The edible portion (pulp) was the only part considered for analysis. Flame atomic absorption spectrometry was used to determine the contents of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), while the levels of chromium (Cr), nickel (Ni), cadmium (Cd), and lead (Pb) were determined using graphite furnace atomic absorption spectrometry. The mean concentrations were 500 Na, 4409 K, 564 Ca, 609 Mg, 1.291 Cu, 6.554 Fe, 2.324 Mn, 2.348 Zn, 0.028 Cr, 0.048 Ni, 0.001 Cd, and 0.003 Pb mg/kg, respectively. Potassium presented the highest contents in all varieties of sweet potatoes. Iron was the most abundant microelement. The orange fleshed sweet potato variety offered greater nutritional contributions to the recommended intakes than the rest of the varieties studied. The estimated mean daily intake of Ni (0.72 mg/day) detected in our samples was highly consistent with other studies. Average daily intakes of Cd (0.015 μg/day) and Pb (0.045 μg/day) were below toxicological reference values. In conclusion, the levels of Cd and Pb detected in the sweet potatoes analyzed do not represent any toxicological risk to consumers.     

Fractionation of heavy metals and assessment of contamination of the sediments of Lake Titicaca

Chemical weathering is one of the major geochemical processes that control the mobilization of heavy metals. The present study provides the first report on heavy metal fractionation in sediments (8–156 m) of Lake Titicaca (3,820 m a.s.l.), which is shared by the Republic of Peru and the Plurinational State of Bolivia. Both contents of total Cu, Fe, Ni, Co, Mn, Cd, Pb, and Zn and also the fractionation of these heavy metals associated with four different fractions have been determined following the BCR scheme. The principal component analysis suggests that Co, Ni, and Cd can be attributed to natural sources related to the mineralized geological formations. Moreover, the sources of Cu, Fe, and Mn are effluents and wastes generated from mining activities, while Pb and Zn also suggest that their common source is associated to mining activities. According to the Risk Assessment Code, there is a moderate to high risk related to Zn, Pb, Cd, Mn, Co, and Ni mobilization and/or remobilization from the bottom sediment to the water column. Furthermore, the Geoaccumulation Index and the Enrichment Factor reveal that Zn, Pb, and Cd are enriched in the sediments. The results suggest that the effluents from various traditional mining waste sites in both countries are the main source of heavy metal contamination in the sediments of Lake Titicaca.     

Spectrophotometric method for the determination of chromium (VI) in water samples

A simple and sensitive spectrophotometric method for the determination of chromium has been developed. The method is based on the diazotization of Dapsone in hydroxylamine hydrochloride medium and coupling with N-(1-Napthyl) Ethylene Diamine Dihydrochloride by electrophilic substitution to produce an intense pink azo-dye, which has absorption maximum at 540 nm. The Beer's law is obeyed from 0.02-1.0 microg mL(-1) and the molar absorptivity is 3.4854 L mol(-1) cm(-1). The Limits of quantification and Limit of detection of the proposed method are 0.0012 microg mL(-1) and 0.0039 microg mL(-1) respectively. The method has been successfully applied for the determination of chromium in water samples and the results were statistically evaluated with that of the reference method.     

Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro,Panama

Environmental and biological reef monitoring was conducted in Almirante Bay (Bahía Almirante) in Bocas del Toro, Panama, to assess impacts from anthropogenic developments. An integrated monitoring investigated how seasonal temperature stress, turbidity, eutrophication and physical impacts threatened reef health and biodiversity throughout the region. Environmental parameters such as total suspended solids [TSS], carbon isotopes (δ¹³C), C/N ratios, chlorophyll a, irradiance, secchi depth, size fractions of the sediments and isotope composition of dissolved inorganic carbon [DIC] of the water were measured throughout the years 2010 and 2011 and were analysed in order to identify different impact sources. Compared to data from Collin et al. (Smithsonian Contributions to the Marine Sciences 38:324–334, 2009) chlorophyll a has doubled at sites close to the city and the port Almirante (from 0.46–0.49 to 0.78–0.97 μg l^?1) and suspension load increased, visible by a decrease in secchi depth values. Visibility decreased from 9-13 m down to 4 m at the bay inlet Boca del Drago, which is strongly exposed to river run off and dredging for the shipping traffic. Eutrophication and turbidity levels seemed to be the determining factor for the loss of hard coral diversity, most significant at chlorophyll a levels higher than 0.5 μg l^?1 and TSS levels higher than 4.7 mg l^?1. Hard coral cover within the bay has also declined, at some sites down to <10 % with extremely low diversities (7 hard coral species). The hard coral species Porites furcata dominated the reefs in highly impacted areas and showed a strong recovery after bleaching and a higher tolerance to turbidity and eutrophication compared to other hard coral species in the bay. Serious overfishing was detected in the region by a lack of adult and carnivorous fish species, such as grunts, snappers and groupers. Study sites less impacted by anthropogenic activities and/or those with local protection showed a higher hard coral cover and fish abundance; however, an overall loss of hard coral diversity was observed.     

Epiphyte toxicity bioassay for ecotoxicological and coastal monitoring

Marine epibionts are organisms that grow on submerged surfaces. Those found on seagrass leaves are especially important because of their interactions with the plants, their contribution to primary production in these ecosystems, and their role as food source for heterotrophic fauna. Given the relative lack of ecotoxicological studies on epibionts, the aim of this study is to evaluate the effect of environmental pollution on epiphytes experimentally attached to artificial devices (mimes) consisting of thermally-sealed silicone tubes supported on bamboo sticks that mimic the morphology of seagrasses and serve as an anchor surface for marine epibionts. Mimes were installed on the sea floor in subtidal waters of the Rio San Pedro (Cádiz), collected after 28 days, and incubated in the laboratory with environmental concentrations of atrazine (herbicide), Irgarol (anti-fouling substance), and copper. Tube-dwelling diatoms formed the major component of the epiphyte community. Average surface covering, chlorophyll, and biomass content did not show significant differences between controls and treatments. The glutathione peroxidase activity increased significantly with 4 μg L^?1 of atrazine and 5 μg L^?1 of copper. This enzymatic activity increase seems to be sufficient to prevent oxidative cellular damage by removing reactive oxygen substances produced by oxidative stress; in addition to this enzyme, there might be other antioxidant enzymes which have not been measured in this study, that have also protected the organism from oxidative damage. Thus, the measurement of antioxidant enzymatic activity in epiphytes may be a useful toxicity indicator for coastal biomonitoring.     

Pollen allergy related to the area of residence in the city of Córdoba,south-west Spain

The aim of this study was to analyse the relationship between the distribution of hay-fever patients in the city of Córdoba, south-western Iberian Peninsula, and the specific atmospheric biological content originating from local sources. Four different districts were established in the metropolitan area of the city, according to vegetational and urbanistic characteristics. Air samples were taken in each area using portable Hirst-type samplers (Lanzoni VPPS 1000) and the spectrum of biological content was defined. Patients attending the Allergy Unit at Córdoba Teaching Hospital in 2000 with allergic rhinitis and/or asthma, and displaying a positive reaction to aeroallergen extracts, were distributed within the areas as a function of their district of residence. Aerobiological results revealed differences in pollen content between areas, in terms of both quantity and number of pollen types recorded. These differences were largely due to proximity to rural areas, prevalence of pollen from typically urban species and the possible effect of urban architecture as a barrier to the dispersal/ concentration of particles and other pollutants. Patients were not uniformly distributed within the city. The majority lived in districts in which pollen from rural species was mixed with pollen from ornamentals. Patients living in typically urban districts displayed a higher prevalence of allergy to pollen from ornamentals. It is concluded that a high degree of exposure to the same environment may influence the development of sensitisation to the particular pollen load associated with that area.     

Precipitation, pH and metal load in AMD river basins: an application of fuzzy clustering algorithms to the process characterization

In the present work, Acid Mine Drainage (AMD) processes in the Chorrito Stream, which flows into the Cobica River (Iberian Pyrite Belt, Southwest Spain) are characterized by means of clustering techniques based on fuzzy logic. Also, pH behavior in contrast to precipitation is clearly explained, proving that the influence of rainfall inputs on the acidity and, as a result, on the metal load of a riverbed undergoing AMD processes highly depends on the moment when it occurs. In general, the riverbed dynamic behavior is the response to the sum of instant stimuli produced by isolated rainfall, the seasonal memory depending on the moment of the target hydrological year and, finally, the own inertia of the river basin, as a result of an accumulation process caused by age-long mining activity.     

A study of the distribution of lead, cadmium and copper between water and kaolin, bentonite and a river sediment

Experiments were carried out to monitor the equilibrium distribution of lead, cadmium and copper between an aqueous phase modelling natural water and a solid phase modelling natural sediment, under varying conditions. The aqueous phase was analysed using ETAAS and differential pulse anodic stripping voltammetry (DPASV), whereas XRD and FTIR were used to study the solid phase. Sorption isotherms at constant pH were measured. Conditional distribution constants were calculated as functions of the pH, the time of equilibration and the amount of solid material. The results obtained stress the need for standardization of the approaches to the study of water-sediment interactions in order to be able to evaluate and compare the extensive data from field measurements and to predict these interactions.     

Assessment of Self-Organizing Map artificial neural networks for the classification of sediment quality

The application of mathematical tools in initial steps of sediment quality assessment frameworks can be useful to provide an integrated interpretation of multiple measured variables. This study reveals that the Self-Organizing Map (SOM) artificial neural network can be an effective tool for the integration of multiple physical, chemical and ecotoxicological variables in order to classify different sites under study according to their similar sediment quality. Sediment samples from 40 sites of 3 estuaries of Cantabria (Spain) were classified with respect to 13 physical, chemical and toxicological variables using the SOM. Results obtained with the SOM, when compared to those of traditional multivariate statistical techniques commonly used in the field of sediment quality (principal component analysis (PCA) and hierarchical cluster analysis (HCA)), provided a more useful classification for further assessment steps. Especially, the powerful visualization tools of the SOM, which offer more information and in an easier way than HCA and PCA, facilitate the task of establishing an order of priority between the distinguished groups of sites depending on their need for further investigations or remediation actions in subsequent management steps.