Determination of total content and isotopic compositions of plutonium and uranium in environmental samples for safeguards purposes by ICP-QMS

The aim of this work was to determine the concentrations and isotopic compositions of plutonium and uranium in environmental samples for safeguards purposes. An analytical method was developed with a plutonium and uranium separation procedure based on extraction chromatography (using 2 mL TEVA and UTEVA columns) and detection with a quadrupole ICP-MS applying an ultra-sonic nebulizer coupled with a membrane desolvation system. Starting from blank swipes, the background equivalent concentration (BEC) was 8 fg for ²³⁹Pu and 1 ng ²³⁸U. The method was successfully applied to certified reference materials as well as to round robin samples obtained in the framework of the inter-laboratory exercise program, promoted by the Brazilian–Argentine Agency for Accounting and Control of Nuclear Materials (ABACC), together with the US Department of Energy (USDOE). After the introduction of an additional ion-exchange separation step, the methodology was applied to the IAEA-384 sediment reference sample with precise and accurate total plutonium and uranium, ²⁴⁰Pu/²³⁹Pu, ²⁴¹Pu/²³⁹Pu, ²³⁴U/²³⁸U and ²³⁵U/²³⁸U atomic ratio results.     

The role of environmental and fisheries multi-controls in white seabream (Diplodus sargus) artisanal fisheries in Portuguese coast

Evaluating the effects of fishing and environmental factors on fish populations are fundamental tenets of fisheries science. In this study, we assess associations between environmental variables (sea surface temperature; North Atlantic Oscillation index; upwelling; wind magnitude; westerly winds; northerly winds; river discharge) and fishing variables (fishing effort) in Diplodus sagus catch rates accounting for regional analyses (northwest coast; southwest coast and Algarve—Algarve south coast). Different time series models for data fitting (multi-model approach) were used. The models were lagged, according to species fishing recruitment age based on the hypothesis that fisheries catches depend on larvae recruitment and survivorship. D. sargus catch rates across areas were unrelated to fishing effort but correlated to environmental variables, with seasonal events explaining much of the variability in trends. On the northwestern coast, the catch rates were mainly set by sea surface temperature (SST) and wind magnitude; however, southwestern coast catch rates were set by NAO winter. On the south coast, only one statistical model (SST, upwelling and westerly winds) associated spring conditions with D. sargus catch rates. The multi-model approach revealed autumn, winter and spring seasonal effects to be related with northwest, southwest and Algarve coastal catch rates, respectively, indicating a possible coastal longitudinal gradient related with given periods of spawning and larval availability. The metadata analysis yielded different results from the regional analyses. In summary, marine resource management should take regional environment characteristics and variability into account when determining sustainable catch rates in given areas for species with high habitat site fidelity.     

Knowing the past to forecast the future: a case study on a relictual,endemic species of the SW Alps, <Emphasis Type="Italic">Berardia subacaulis</Emphasis>

Future climate change may lead to a substantial loss of biodiversity, particularly affecting mountain regions, including the Alps. Range-size reduction in high mountain plant species is predicted to be more pronounced for endemic species. Investigating the broad temporal spectrum of range shifts is important for the conservation of biodiversity, since learning how species responded to climate change in the past provides useful insights on how they might react to warming trends in the present and future. Using species distribution models and an ensemble forecasting approach, we explored how the distribution of Berardia subacaulis, a monospecific genus endemic of the south-west Alps, may be affected by past and future projected climate change. During the last interglacial, the habitat suitability of Berardia was lower than present and a progressive increase was observed from the last glacial maximum until now. In the future, Berardia appears to lose more than 80 % of its range, becoming endangered by 2050. Our results suggest that Berardia probably survived past warmer periods in situ, expanding its distributional range during cooler periods. The severe future range contraction predicted for Berardia reflects similar results for other endemic species. As Berardia represents an interesting model species to evaluate the effects of climate warming on range size and shifts, demographic and precise range monitoring may be undertaken on this species.     

Historical deforestation as a cause of alluviation in small valleys, subcarpathian loess plateau, Poland

The undulating loess Kanczuga Plateau, 250–270 m a.s.l., is located in the temperate climatic zone of Central Europe, within the northern foreland of the Carpathians. It is dissected by a network of valleys 30–60 m deep, infilled with several metres of complex minerogenic and organic deposits which started to accumulate during the early Holocene. The southern side of one of these valleys is dissected by several dry valleys. The mouth sections of these valleys have buried surface comprising peat and/or organic silts, overlain by sandy–silty alluvium. ¹⁴C dates indicate that the alluviation of these valley floors, which proceeded from the headwaters to the mouth sections, began in the 1100 ad. The gradual intensification of soil erosion in the upper part of the catchment and associated sedimentation probably encompassed only a few centuries, with greatest alluviation during the Little Ice Age. This plateau, which is under the influence of more continental climatic conditions than the low-mountain and upland regions of Western Europe, features more climatic contrasts. Here environmental changes triggered by land use were superimposed on climatic change. The most intensive processes of soil erosion and sediment transfer as well as alluviation, coincided with the first phase of cooling during the Little Ice Age. It was the final stage of the intensification of these processes, probably more intensive than its initial phase in the eleventh century, caused primarily by deforestation resulting from the development of agriculture.     

PCB congener specific oxidative stress response by microarray analysis using human liver cell line

In this study we have examined the effect of exposure to different congeners of PCBs and their role in oxidative stress response. A metabolically competent human liver cell line (HepG2) was exposed with two prototype congeners of PCBs: coplanar PCB-77 and non-coplanar PCB-153. After the predetermined times of exposure (0–24 h) at 70 μM concentration, the HepG2 cells showed significant apoptotic changes by fluorescent microscopy after 12 h of exposure. Gene set enrichment analysis (GSEA) identified oxidative stress as the predominant enrichment. Further, paraquat assay showed that PCB congeners lead to oxidative stress to different extents, PCB-77 being more toxic. This study, with emphasis on all recommended microarray quality control steps, showed that apoptosis was one of the most significant cellular processes as a result of oxidative stress, but each of these congeners had a unique signature gene expression, which was further validated by Taqman real time PCR and immunoblotting. The pathways involved leading to the common apoptotic effect were completely different. Further in-silico analysis showed that PCB-153 most likely acted through the TNF receptor, leading to oxidative stress involving metallothionein gene families, and causing apoptosis mainly by the Fas receptor signaling pathway. In contrast, PCB-77 acted through the aryl hydrocarbon receptor. It induced oxidative stress through the involvement of cytochrome P450 (CYP1A1) leading to apoptosis through AHR/ARNT pathway.     

Integrating forage,wildlife, water,and fish projections with timber projections at the regional level: A case study in southern United States

The impact of timber management and land-use change on forage production, turkey and deer abundance, red-cockaded woodpecker colonies, water yield, and trout abundance was projected as part of a policy study focusing on the southern United States. The multiresource modeling framework used in this study linked extant timber management and land-area policy models with newly developed models for forage, wildlife, fish, and water. Resource production was integrated through a commonly defined land base that could be geographically partitioned according to individual resource needs. Resources were responsive to changes in land use, particularly human-related, and timber management, particularly the harvest of older stands, and the conversion to planted pine.     

Denitrification potential and organic matter as affected by vegetation community, wetland age, and plant introduction in created wetlands

Denitrification potential (DP) and organic matter (OM) in soils were compared in three different vegetation communities-emergent macrophyte, open water, and forested edge-in two 10-yr-old created riverine wetlands. Organic matter, cold water-extractable organic matter (CWEOM), anaerobic mineralizable carbon (AnMC), and DP varied significantly (P<0.05) among vegetation communities. The surface (0 to 9 cm) soils in the emergent macrophyte community (EMC) showed highest DP (0.07+/-0.01 mg N h-1 kg-1), OM (84.90+/-5.60 g kg-1), CWEOM (1.12+/-0.20 g kg-1), and AnMC (1.50+/-0.10 mg C h-1 kg-1). In the deeper layer (9 to 18 cm), DP and CWEOM (0.04+/-0.01 mg N h-1 kg-1 and 1.13+/-0.20 g kg-1, respectively) were significantly higher in the open water community (OWC) than in the emergent macrophyte and forested edge communities. Plant introduction did not affect DP or OM content and characteristics. After 10 yr of wetland development, mean DP increased 25-fold in the surface layer (from 0.002 to 0.053 mg N h-1 kg-1); OM content more than doubled to 90.80+/-19.22 g kg-1, and CWEOM and HWEOM increased 2.5 and 2.7 times respectively from 1993 (prewetland conditions) to 2004. Humic acids were the most abundant form of OM in 2004 and 1993 samples. Significant (P<0.05) positive relationships between DP and OM, CWEOM, and AnMC were found in the surface layer; in the 9- to 18-cm layer, significant positive relationships were found between DP and CWEOM and AnMC.