Long-term patterns in tropical reforestation: plant community composition and aboveground biomass accumulation.

Primary tropical forests are renowned for their high biodiversity and carbon storage, and considerable research has documented both species and carbon losses with deforestation and agricultural land uses. Economic drivers are now leading to the abandonment of agricultural lands, and the area in secondary forests is increasing. We know little about how long it takes for these ecosystems to achieve the structural and compositional characteristics of primary forests. In this study, we examine changes in plant species composition and aboveground biomass during eight decades of tropical secondary succession in Puerto Rico, and compare these patterns with primary forests. Using a well-replicated chronosequence approach, we sampled primary forests and secondary forests established 10, 20, 30, 60, and 80 years ago on abandoned pastures. Tree species composition in all secondary forests was different from that of primary forests and could be divided into early (10-, 20-, and 30-year) vs. late (60- and 80-year) successional phases. The highest rates of aboveground biomass accumulation occurred in the first 20 years, with rates of C sequestration peaking at 6.7 +/- 0.5 Mg C x ha(-1) x yr(-1). Reforestation of pastures resulted in an accumulation of 125 Mg C/ha in aboveground standing live biomass over 80 years. The 80 year-old secondary forests had greater biomass than the primary forests, due to the replacement of woody species by palms in the primary forests. Our results show that these new ecosystems have different species composition, but similar species richness, and significant potential for carbon sequestration, compared to remnant primary forests.     

Results and evaluation of the first study of organochlorine contaminants (PCDDs, PCDFs, PCBs and DDTs), heavy metals and metalloids in birds from Baja California, México

Organochlorine compounds (OCs) including polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p-p'-DDE), heavy metals (Pb, Cd, Zn, Cu), and arsenic were measured in house sparrows (Passer domesticus) and common ground doves (Columbina passerina) from Baja California Sur, México. Concentrations of PCDD/Fs were low, with 21 pg/g for house sparrows, and 7.7 pg/g for common ground doves. Non-ortho-PCB concentrations in house sparrow and common ground doves were 58 and 254 pg/g, respectively, and are within the highest concentrations reported in species that are in the low levels of food webs. The major differences in organochlorine levels between species were found for ortho-PCBs and DDTs. ortho-PCB levels were higher in the seedeater species, whereas DDT levels were higher in the omnivorous species. Heavy metal levels were far below those associated with negative effects.     

Modeling the Entrepe?as Reservoir.

The Entrepe?as Reservoir is a monomictic reservoir located in River Tagus (Spain). The aim of this work is to establish a feasible model to predict the depth of the thermocline that is developed in the reservoir during the period of natural thermal stratification. Entrainment, eddy diffusion, inflow of external energy, and other factors are considered to calibrate the parameters of the model. The methodology involves the measure of actual temperature and electrical conductivity profiles, use of meteorological data and reservoir parameters, and selection and application of several models from the literature. The calculations and predictions are integrated to a software packet that is able to predict thermocline depth and water temperature profile during a 1-year period on a day-by-day basis. In the thermocline depth, the prediction error, on the basis of real data, is less than 6% and, in the water temperature, it is 2 degrees C.     

Antifungal and anti-aflatoxigenic activity of Heliopsis longipes roots and affinin/spilanthol against Aspergillus parasiticus by downregulating the expression of alfD and aflR genes of the aflatoxins biosynthetic pathway

Abstract

In the present study, ethanolic extract from Heliopsis longipes roots and affinin/spilanthol against Aspergillus parasiticus growth and aflatoxins production were studied in relation to the expression of aflD and aflR, two key genes of aflatoxins biosynthetic pathway. Phytochemical analysis of the ethanolic extract by GC-EIMS identified affinin/spilanthol (7.84?±?0.27?mg g^?1) as the most abundant compounds in H. longipes roots. The antifungal and anti-aflatoxigenic assays showed that affinin/spilanthol at 300?µg mL^?1 produced the higher inhibition of radial growth (95%), as well as, the higher aflatoxins production inhibition (61%) in comparison to H. longipes roots (87% and 48%, respectively). qRT-PCR revealed that the expression of aflD and aflR genes showed a higher downregulation in affinin/spilanthol at 300?µg mL^?1. The expression ratio of alfD was suppressed by affinin/spilanthol in 79% and aflR in 84%, while, a lower expression ratio suppressed by H. longipes was obtained, alfD (55%) and aflR (59%). Affinin/spilanthol possesses higher antifungal and anti-aflatoxigenic activity against A. parasiticus rather than H. longipes roots, and this anti-aflaxotigenic activity occurring via downregulation of the aflD and aflR genes. Thus, H. longipes roots and affinin/spilanthol can be considered potent antifungal agents against aflatoxigenic fungus, especially, affinin/spilanthol.     

Biomonitoring of heavy metals and air quality in Cordoba City, Argentina, using transplanted lichens

The objective of the present study was to test the concentrations of some elements in the transplanted lichen Usnea amblyoclada transplanted in Córdoba, Argentina, and to investigate the relative air quality of the area as indicated by a Pollution Index. Analyses of Cu, Co. Pb, Fe, Ni, Mn, S and Zn in addition to analyses of physiological parameters were performed after the transplantation period. No significant differences were observed among the sampling stations for the physiological parameters, except the dry weight/fresh weight ratio. The concentration of most elements was similar to or lower than those found in non-polluted and even polluted areas. The significant correlation found between Cu, Pb and Zn with the content of hydroperoxy conjugated dienes suggests an important oxidative effect probably caused by these ions. The distribution patterns of the elements were quite similar, with maximum values around a cement plant and the metallurgical industries. The Pollution Index distribution pattern does not coincide with the elements distribution, due to the fact that the index values probably reflected the emissions of gaseous phytotoxic pollutants.     

Is the flower fluorescence relevant in biocommunication?

Flower fluorescence has been previously proposed as a potential visual signal to attract pollinators. In this work, this point was addressed by quantitatively measuring the fluorescence quantum yield (Φ _f) for flowers of Bellis perennis (white, yellow, pink, and purple), Ornithogalum thyrsoides (petals and ovaries), Limonium sinuatum (white and yellow), Lampranthus productus (yellow), Petunia nyctaginiflora (white), Bougainvillea spectabilis (white and yellow), Antirrhinum majus (white and yellow), Eustoma grandiflorum (white and blue), Citrus aurantium (petals and stigma), and Portulaca grandiflora (yellow). The highest values were obtained for the ovaries of O. thyrsoides (Φ _f?=?0.030) and for Citrus aurantium petals (Φ _f?=?0.014) and stigma (Φ _f?=?0.013). Emitted photons as fluorescence were compared with reflected photons. It was concluded that the fluorescence emission is negligible compared to the reflected light, even for the most fluorescent samples, and it may not be considered as an optical signal in biocommunication. The work was complemented with the calculation of quantum catches for each studied flower species to describe the visual sensitization of eye photoreceptors.     

Antiestrogenic activity of anthropogenic and natural chemicals

A number of natural and man-made chemicals possess antiestrogenic activity, i.e. they antagonize a broad spectrum of estrogen-induced responses in vertebrates. Examples of antiestrogens include dioxin, furan and PCB congeners, certain PAHs, pesticides and indol-3-carbinol derivatives. Major mechanisms of antiestrogenicity are antagonistic action of chemicals at the estrogen receptor, or binding of chemicals to the arylhydrocarbon (Ah) receptor and subsequent interaction with estrogen-responsive genes. Toxicological consequences resulting from antiestrogenic activity have not been conclusively demonstrated to date, although antiestrogenic compounds could critically affect sensitive reproductive and developmental processes.     

Measurements of selected PCBs in open urban ambient air of Madrid (Spain)

The focus of this study was to characterize the concentration levels of selected PCBs and compare them to compiled data in order to contribute to the international database. The sampling site is located in the outskirts of Madrid and can be considered an open urban area. 32 samples of air were taken from February 1998 to June 1998 by using a high volume air sampler. Glass fiber filters and polyurethane foam (PUF) were used to collect the paniculate and gas phase material, respectively. PUF plugs were Soxhlet extracted and filters were ultrasonically extracted by using pesticide-grade hexane and dichloromethane, respectively. The cleanup procedure was carried out on a florisil column with hexane and hexane/dichloromethane as elution solvents. GC/MS in a selected ion monitoring mode was used for quantification and 29 selected PCBs congeners were analyzed.     

Determination of polychlorinated biphenyl and polycyclic aromatic hydrocarbon marine regional Sediment Quality Guidelines within the European Water Framework Directive

Marine regional Sediment Quality Guidelines (SQG) for polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) from the Basque coast (SE Bay of Biscay) were determined, on the basis of sediment chemistry, toxicity and benthic community disturbance from analysis of 756 estuarine and coastal samples. The SQG were calculated using a percentile approach (based upon effect and non-effect data), using non-normalised and normalised concentration, by total organic carbon. However, normalisation by total organic carbon did not result in any improvement in accuracy compared with non-normalised values. Hence, this study proposes non-normalised SQG values for assessment of the chemical and physicochemical status in marine waters in the Basque Country, within the Water Framework Directive: 24.6–29 μg kg^?1 for total PCBs; 164–285 μg kg^?1 for low molecular weight PAH; 922–1537 μg kg^?1 for high molecular weight PAH; and 1607–2617 μg kg^?1 for total PAH.     

Platinum in PM2.5 of the metropolitan area of Mexico City

The increase in platinum (Pt) in the airborne particulate matter with size ≤2.5 µm (PM_2.5) in urban environments may be interpreted as result of the abrasion and deterioration of automobile catalyst. Nowadays, about four million vehicles in Mexico City use catalytic converters, which means that their impact should be considered. In order to evaluate the contribution of Pt to environmental pollution of the metropolitan area of Mexico City (MAMC), airborne PM_2.5 was collected at five different sites in the urban area (NW, NE, C, SW, SE) in 2011 during April (dry-warm season), August (rainy season) and December (dry-cold season). Analytical determinations were carried out using a ICP-MS with a collision cell and kinetic energy discrimination. The analytical and instrument performance was evaluated with standard road dust reference material (BCR-723). Median Pt concentration in the analyzed particulate was is 38.4 pg m^?3 (minimal value 1 pg m^?3 maximal value 79 pg m^?3). Obtained Pt concentrations are higher than those reported for other urban areas. Spatial variation shows that SW had Pt concentration significantly higher than NW and C only. Seasonal variation shows that Pt median was higher in rainy season than in both dry seasons. A comparison of these results with previously reported data of PM₁₀ from 1991 and 2003 in the same studied area shows a worrying increase in the concentration of Pt in the air environment of MAMC.