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Jorge Yáñez Marjory Guajardo Cristian Miranda César Soto Héctor D. Mansilla A. Russell Flegal 《Marine pollution bulletin》2013
Anomalously high levels of mercury in sediment in the Lenga estuary, Chile are comparable to the most contaminated sites previously reported elsewhere. Total mercury (Hgtotal) concentrations range from 0.5 to 129 mg kg−1 and organic mercury (Hgorg) from 11 to 53 μg kg−1. The highest levels are in areas near the previous wastewater outfall of a chlo-alkali plant. The results show that the proportion of Hgorg/Hgtotal in the sediment varies by more than two orders of magnitude (0.02–5.7%) according to the concentration of Hgtotal. No correlation between the concentration of Hgorg and Hgtotal was found. The lack of correlation does contrast with the findings of other authors in culture media. Our results indicate that even at very high concentrations of Hgtotal and organic matter do not influence organic mercury formation in estuary sediments. The disparity in Hgtotal and Hgorg concentrations also attests to environmental differences in the formation. 相似文献
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Natural Hazards - As a result of the massive deforestation and windfalling in Romania last year, catastrophic floods frequently occur with historic high-water marks only to be registered every 500... 相似文献
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We studied, separately, the effect of the cladocerans Alona glabra and Macrothrix triserialis on the population growth of the rotifer Euchlanis dilatata using three different food types (Chlorella and Scenedesmus, live or dead, offered on a comparable dry weight basis, 3.16 μg C ml−1). Regardless of the presence or absence of competition, E. dilatata cultured using Chlorella (live or dead) showed a higher population growth as compared to Scenedesmus. Compared to heat-killed C. vulgaris, E. dilatata cultured alone and fed on live algae reached higher abundances. Both cladoceran species had an adverse effect on the population growth of Euchlanis, but did not eliminate the rotifers. Of the two cladocerans, M. triserialis had a far more adverse effect on the population densities of E. dilatata as compared to A. glabra. E. dilatata also influenced the population growth of A. glabra and M. triserialis, the former being more adversely affected than the latter. When the egg ratios of E. dilatata were plotted as a function of population density, a significantly inverse relation was obtained only in treatments containing Chlorella but not for other treatments. Statistically the rate of population increase (r) per day of E. dilatata was adversely affected by the diet type and the presence of competing species. The interaction of diet type X competition was also significant. For A. glabra, the presence of E. dilatata and the diet type, but not their interaction, significantly influenced the r. On the other hand for M. triserialis, only the diet type was significant. Our results suggest that the competitive outcome between rotifers and cladocerans was dependent on diet type. 相似文献
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Diana Jordanova Petar Petrov Viktor Hoffmann Tilman Gocht Cristian Panaiotu Tsenka Tsacheva Neli Jordanova 《Studia Geophysica et Geodaetica》2010,54(3):417-442
Detailed magnetic study on vegetation samples from several strongly polluted and clean sites in Bulgaria is carried out in
order to evaluate suitability of different species as passive dust collectors in magnetometry. From each location, available
species among lichens, mosses, poplar leaves, dandelion, needles have been sampled. Magnetic susceptibility calculated on
mass-specific basis shows wide variability between diamagnetic signal up to 846 × 10−8 m3/kg. Lichens and mosses are found to be the species, showing magnetic signals with the strongest contrast between clean and
polluted environment. The main magnetic phase is magnetite-like according to the results from thermomagnetic analysis of susceptibility
on magnetic extracts. Scanning electron microscopy (SEM) microphotographs reveal the presence of abundant particulate matter
on vegetation surface both with anthropogenic (spherules) and lithogenic origin. Magnetic grain size deduced by the ratio
of saturation remanent magnetization (SIRM) and mass-specific magnetic susceptibility (χ) and coercivities (Bc and Bcr) suggest that different species accumulate preferentially small SD-like grains from pollution emissions. Contrasting relationship
of the ratio of anhysteretic remanent magnetization (ARM) and χ for polluted vs clean sites deduced by needles and lichens
may be related to transformation of the accumulated dust particles within lichens’ tissue. This finding indicates that the
exact species used as biological dust collector is of importance when studying spatial grain size distribution of magnetic
dust particles. Pilot study on polycyclic aromatic hydrocarbons (PAH) content and its relation to magnetic parameters shows
good correspondence between high levels of PAHs and high SIRM values for locations affected by non-ferrous industrial production. 相似文献
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Knowledge of the driving forces behind indigenous participation in the market is essential for practitioners intending to integrate conservation and development policies in indigenous territories. Nevertheless, empirical research on the determinants of market integration among indigenous peoples is still scarce. This article uses household survey data and multivariate techniques to examine the drivers of market integration among indigenous groups in the Ecuadorian Amazon. We use multiple measures of market integration, including the sale of crops, timber, and wildlife; the use of credit; and participation in wage labor. The results show that the way in which indigenous peoples integrate into the market depends on their endowments of human, financial, and physical capital. More educated households are able to engage in commercial agriculture and nonagricultural wage work, whereas uneducated poor households in communities in conflict with outsiders are pushed to engage in poorly paid agricultural wage work and (often illegal) timber operations. 相似文献
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Liviu?Mihai?Irimia Cristian?Valeriu?PatricheEmail author Hervé?Quenol Lucian?Sf?c? Chris?Foss 《Theoretical and Applied Climatology》2018,131(3-4):1069-1081
Climate change is causing important shifts in the suitability of regions for wine production. Fine scale mapping of these shifts helps us to understand the evolution of vineyard climates, and to find solutions through viticultural adaptation. The aim of this study is to identify and map the structural and spatial shifts that occurred in the climatic suitability for wine production of the Cotnari wine growing region (Romania) between 1961 and 2013. Discontinuities in trends of temperature were identified, and the averages and trends of 13 climatic parameters for the 1961 to 1980 and 1981 to 2013 time periods were analysed. Using the averages of these climatic parameters, climate suitability for wine production was calculated at a resolution of 30 m and mapped for each time period, and the changes analysed. The results indicate shifts in the area’s historic climatic profile, due to an increase of heliothermal resources and precipitation constancy. The area’s climate suitability for wine production was modified by the loss of climate suitability for white table wines, sparkling wines and wine for distillates; shifts in suitability to higher altitudes by about 67 m, and a 48.6% decrease in the area suitable for quality white wines; and the occurrence of suitable climates for red wines at lower altitudes. The study showed that climate suitability for wine production has a multi-level spatial structure, with classes requiring a cooler climate being located at a higher altitude than those requiring a warmer climate. Climate change has therefore resulted in the shift of climate suitability classes for wine production to higher altitudes. 相似文献