Responses to ozone pollution of alfalfa exposed to increasing salinity levels

Stomatal closure and biosynthesis of antioxidant molecules are two fundamental components of the physiological machinery that lead to stress adaptation during plant's exposure to salinity. Since high stomatal resistance may also contribute in counteracting O₃ damages, we hypothesized that soil salinization may increase O₃ tolerance of crops. An experiment was performed with alfalfa grown in filtered (AOT40 = 0 in both years) and non-filtered (AOT40 = 9.7 in 2005 and 6.9 ppm h in 2006) open-top chambers. Alfalfa yield was reduced by O₃ (−33%) only in plants irrigated with salt-free water, while the increasing levels of soil salinity until 1.06 dS m⁻¹ reduced both stomatal conductance and plant O₃ uptake, thus linearly reducing O₃ effects on yield. Therefore a reliable flux-based model for assessing the effects of O₃ on crop yield should take into account soil salinity.     

Using optical remote sensing techniques to track the development of ozone-induced stress

In this paper, a literature review about optical remote sensing (RS) of O₃ stress is presented. Studies on O₃-induced effects on vegetation reflectance have been conducted since late ‘70s based on the analysis of optical RS data. Literature review reveals that traditional RS techniques were able to detect changes in leaf and canopy reflectance related to O₃-induced stress when visible symptoms already occurred. Only recently, advanced RS techniques using hyperspectral sensors, demonstrated the feasibility of detecting the stress in its early phase by monitoring excess energy dissipation pathways such as chlorophyll fluorescence and non-photochemical quenching (NPQ). Steady-state fluorescence (Fs), measured by exploiting the Fraunhofer line depth principle and NPQ related xanthophyll-cycle, estimated through the photochemical reflectance index (PRI) responded to O₃ fumigation before visible symptoms occurred. This opens up new possibilities for the early detection of vegetation O₃ stress by means of hyperspectral RS.     

A transgenic approach to enhance phosphorus use efficiency in crops as part of a comprehensive strategy for sustainable agriculture

Concerns about phosphorus (P) sustainability in agriculture arise not only from the potential of P scarcity but also from the known effects of agricultural P use beyond the field, i.e., eutrophication leading to dead zones in lakes, rivers and coastal oceans due to runoffs from fertilized fields. Plants possess a large number of adaptive responses to P_i (orthophosphate) limitation that provide potential raw materials to enhance P_i scavenging abilities of crop plants. Understanding and engineering these adaptive responses to increase the efficiency of crop capture of natural and fertilizer P_i in soils is one way to optimize P_i use efficiency (PUE) and, together with other approaches, help to meet the P sustainability challenge in agriculture. Research on the molecular and physiological basis of P_i uptake is facilitating the generation of plants with enhanced P_i use efficiency by genetic engineering. Here we describe work done in this direction with emphasis on the up-regulation of plant proton-translocating pyrophosphatases (H⁺-PPases).     

Lichen and moss bags as monitoring devices in urban areas. Part I: influence of exposure on sample vitality

Samples of the lichen Pseudevernia furfuracea (L.) Zopf and the moss Hypnum cupressiforme Hedw. were exposed for 6 weeks in nylon bags in two air pollution monitoring stations in Trieste and Naples (Italy) with different climates and pollution loads to evaluate influence of environmental conditions on sample vitality. This was assessed before and after exposure by transmission electron microscopy observations, K cellular location, and measurements of C, N, S and photosynthetic pigments content, CO2 gas exchange, and chlorophyll fluorescence. Almost all data sets indicate that exposures caused some damage to the species, considerably heavier in the moss, especially in Naples. The two cryptogams differed significantly in accumulation and retention of C, N, and S, the lichen clearly reflecting NO2 availability. The difference in vitality loss was related to the different ecophysiology of the species, because concentrations of phytotoxic pollutants were low during exposure. Critical notes on the analytical techniques are also given.     

Records of polychlorinated biphenyls (PCBs) in sediments of four remote Chilean Andean Lakes

Sediment cores from four Chilean lakes along the Andes Chain (Chungará, Laja, Castor and Venus) were analysed in order to investigate PCB concentrations and distributions in sediment samples. Sediment cores were analysed for PCBs using gas chromatography (GC-ECD/MS) and radioisotopically dated using 210Pb. Organic carbon content (OC) and 210Pb fluxes were also measured. Results showed that sediment PCB concentrations (ngg(-1) d.w.) at Lake Chungará (1.2 +/- 1) in northern Chile, Laja (5 +/- 4) in central, and in Lake Castor (3.5 +/- 4) in southern Chile (the eastern side of the Andes Mountain) were lower than sediments collected from Lake Venus (64 +/- 30) located in southern Chile (the western side) which contained 15-fold higher concentrations of PCBs. The percentage (%) of organic carbon was variable and showed a high range of values in the sediment fluctuating from 2% (Lake Laja) to 22% (Lake Chungará). Analysis of 210Pb fluxes, presented a decrease trend following Lake Laja>Castor>Chungará with a positive correlation with rainfall at each site. Sedimentation rates in Lake Castor (1846 gm(-2)yr(-1)) were higher than at Chungará (748 gm(-2)yr(-1)) and Lake Laja (508 gm(-2)yr(-1)). Focusing factor (FF) is used as a tool to elucidate PCB input in the aquatic ecosystem. FF were lower (<1) for the shallower lakes (Lakes Chungará and Castor). This study provides background levels of PCBs at remote lakes in Chile. Differences in geographical characteristics (orographic effect) might play an important role in the arrival of PCBs, particularly into the southern lakes. PCB fluxes indicated deposition of PCBs in recent sediments is higher than in previous years with peaks of PCB between 1991 and 1998. The continuing increase of PCB inputs in remote Chilean lakes, could be associated with long range atmospheric transport (LRAT).     

High concern chemicals in top layer sediments of the northern Adriatic seabed as markers of old waste dumpings

The results are presented of a survey planned to assess the presence of high concern chemicals in sediments collected in a northern sector of the Adriatic sea neighboring the Venice lagoon. For the assessment, persistent marker chemicals were selected from the families of polycyclic aromatic hydrocarbons, polychlorobiphenyls, polychlorodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), and chlorinated pesticides. Based on the chemical-specific concentrations and PCDD+PCDF profiles determined in the sediments analyzed, dumping zones appear to have existed approximately 5-6km away from lagoon shoreline. Contamination levels exceed the quality criteria established by the pertinent Italian national regulation at many sampling sites, eventually reflecting ("fingerprinting") industrial activities once performed in the industrial settlement of Porto Marghera within the Venice lagoon. In coastal samples, concentration levels appear to be lower than those determined at offshore sampling sites.     

Population Declines and Priorities for Amphibian Conservation in Latin America

Abstract: Although dramatic amphibian population declines have been reported worldwide, our understanding of the extent of the declines in Latin America, where amphibian diversity is high, is limited to a few well-documented studies. To better understand the geographic extent of declines, their possible causes, and the measures needed to improve Latin American scientists' ability to research the phenomenon and make effective management recommendations, we convened three regional workshops with 88 Latin American herpetologists and conservationists. Population declines are widespread in Latin America. At least 13 countries have experienced declines, and in 40 cases species are now thought to be extinct or extirpated in a country where they once occurred. Declines or extinctions have affected 30 genera and nine families of amphibians. Most declines have occurred in remote highlands, above 500 m in elevation in Central America and above 1000 m in the Andes. Most documented declines occurred in the 1980s. Of the possible causes studied to date, climate change appears to be important at one site and chytrid fungal disease has been identified at sites in three countries. Although many monitoring studies are currently underway in a variety of habitats, most studies are recent and of short duration. In a signed resolution, workshop participants called for greater collaboration and communication among scientists working in Latin America to understand the geographic extent of population declines and the distribution of possible causal factors. In situ conservation is important to protect habitats, but captive-rearing programs for species subject to imminent extinction are also needed. Better understanding of the taxonomy and natural history of amphibians and more funding for research and monitoring are critical to developing a scientific basis for management action to arrest and reverse population declines.     

Heavy metals in the liver and muscle of <Emphasis Type="Italic">Micropogonias manni</Emphasis> fish from Budi Lake,Araucania Region,Chile: potential risk for humans

The concentrations of cadmium, lead, manganese and zinc were determined in the fish species Micropogonias manni captured in Budi Lake, Araucanía Region (Chile). The measurements were made by atomic absorption spectroscopy, and the analysis considered the sex, weight and size of the species; the representative samples were taken from the liver and muscle tissue. The method was validated using certified reference material (DOLT-1). The ranges of concentrations found in the muscle tissue were: Cd, not determinate (n.d.)–0.26; Pb, n.d.–1.88; Mn, 0.02–12.17 and Zn, 0.48–39.04 mg kg⁻¹ (dry weight). The concentrations in muscle tissue were generally lower than those found in the liver. With respect to the average concentrations recorded for each metal in the edible part of the fish (muscle tissue), it was found that the levels of Cd, Pb, Mn and Zn are within the ranges published by other authors in similar works and below the maximum concentration limits permitted by current legislation (FAO/WHO 2004; EU 2001) and do not constitute a health hazard for consumers of this species. The results were subjected to statistical analysis to evaluate the correlations between the content of the various metals and the sex, weight and size of each sample.     

Kriging and Bilinear Methods for Estimating Spatial Pattern of Atmospheric Pollutants

Two statistical methods to reconstruct the spatial pattern ofenvironmental data are compared: the Kriging and the Bilinear.The comparison is performed by evaluating two differentcharacteristics of the methods: the interpolation and the estimation. The Kriging method is demonstrated to be better thanthe Bilinear regarding all the statistics studied, although thedifferences are not very significant. Especially, the Kriging ismore efficient than the Bilinear in the reconstruction of peakvalues and it does not extrapolate local trends. The methods areapplied to a set of environmental data measured in an urban area.