Urbanization effects on shoreline phytobenthos: a multiscale approach at lake extent

To understand how littoral biota respond to anthropogenic disturbances, limnologists seek to detect the scale at which patterns and processes occur. We conducted an extensive study on the shoreline phytobenthos of Lake Garda (Italy) with the following main objectives: (i) to examine the importance of urbanization for species distribution within a set of hierarchical spatial scales (10¹–10⁴ m), and then (ii) to test the spatio-temporal interactions on a reduced set of scales (10¹–10² m, and 10¹–10² days). Results showed that most of the variation in most abundant species and habitat characteristics occurred at the spatial scale of 10¹–10² m. Species richness was positively related with microheterogeneity, but the relationship occurred only at low urbanization and not at highly-urbanized sites where artificial shores were less heterogeneous. The similarity of species assemblages was regulated by two interacting processes, one operating at a fine spatial scale (10² m), reflecting the physical-habitat requirements of the species, and the other one operating at a broader scale (10⁴ m) in relation to the N–S nitrogen gradient. Overall, time explained 73 % of the total variation of species assemblages, space 7 %, and 20 % was explained by the interaction between space and time (the patch scale, 10s of m, and area scale, 100s of m, interacted with the finest temporal scale, 10s of days). This interaction might be explained by the process of species recruitment operating at different rates at the two spatial scales. Since the largest variation in species assemblages was at the temporal scale (due to the seasonal succession of phytobenthos), we recommend collecting at least one sample per season when monitoring littoral habitats.     

Benthic respiration and stoichiometry of regenerated nutrients in lake sediments with Dreissena polymorpha

The effect of patchy colonies of the invasive zebra mussel (Dreissena polymorpha) on sedimentary processes was investigated in a mesotrophic lake (Plateliai Lake, Lithuania). Benthic fluxes of O₂, TCO₂, CH₄, Mn²⁺, Fe²⁺, N₂, the inorganic forms of N, Si and P and dissolved organic C and N were quantified by dark incubations of sediments cores, with and without D. polymorpha. Individual mussels also were incubated for metabolic measurements. Sediments with D. polymorpha had significantly higher O₂ and TCO₂ fluxes and displayed higher rates of denitrification. The presence of mussels also resulted in higher regeneration of P and N (mostly as ammonium) while the effect on Si was not significant. However, likely due to the low zebra mussel biomass (57.2 ± 25.3 g_SFDW m^?2), biodeposition has not changed the ratio between anaerobic and total respiration. Methane and reduced metals fluxes were in fact similar in the presence and absence of D. polymorpha. Incubations of mussels without sediments confirmed that bivalve metabolism was the main driver of benthic respiration and nutrient recycling. Nitrate production suggested the presence of nitrifiers associated with the molluscs. The main outcome of this study was that zebra mussels alter the quantity and the stoichiometry of nutrients regenerated by the benthic compartment. The enhancement of nitrogen loss via denitrification, by a factor of 1.5, was much less pronounced than the increase in ammonium recycling rate, stimulated by a factor of 33. Negligible PO₄ ^3? fluxes in bare sediments (?3.4 ± 6.8 μmol m^?2 h^?1) increased in the presence of mussels and considerable amounts of this nutrient (69.6 ± 29.4 μmol m^?2 h^?1) were mobilized to the water column. Further research should address other nutrient sources to the lake to verify whether altered rates and stoichiometry of benthic regeneration can affect primary producer community composition and activity.     

The BEAM-project: prediction and assessment of mixture toxicities in the aquatic environment

Freshwater and marine ecosystems are exposed to various multi-component mixtures of pollutants. Nevertheless, most ecotoxicological research and chemicals regulation focus on hazard and exposure assessment of individual substances only, the problem of chemical mixtures in the environment is ignored to a large extent. In contrast, the assessment of combination effects has a long tradition in pharmacology, where mixtures of chemicals are specifically designed to develop new products, e.g. human and veterinary drugs or agricultural and non-agricultural pesticides. In this area, two concepts are frequently used and are thought to describe fundamental relationships between single substance and mixture effects: Independent Action (Response Addition) and Concentration Addition. The question, to what extent these concepts may also be applied in an ecotoxicological and regulatory context may be considered a research topic of major importance, as the concepts would allow to make use of already existing single substance toxicity data for the predictive assessment of mixture toxicities. Two critical knowledge gaps are identified: (a) There is a lack of environmental realism, as a huge part of our current knowledge about the applicability of the concepts is restricted to artificial situations with respect to mixture composition or biological effect assessment. (b) The knowledge on what exactly is needed for using the concepts as tools for the predictive mixture toxicity assessment is insufficient. Both gaps seriously hamper the necessary, scientifically sound consideration of mixture toxicities in a regulatory context.In this paper, the two concepts will be briefly introduced, the necessity of considering the toxicities of chemical mixtures in the environment will be demonstrated and the applicability of Independent Action and Concentration Addition as tools for the prediction and assessment of mixture toxicities will be discussed. An overview of the specific aims and approaches of the BEAM project to fill in the identified knowledge gaps is given and first results are outlined.     

1990s长江流域降水趋势分析

依据国家气象局提供的实测月降水和日降水资料,运用Mann-Kendall(M-K)非参数检验法验证了降水趋势,并通过空间插补法,由点扩展到面,分析了1990s长江流域降水变化特征,发现1990s长江流域降水变化以降水在时间和空间分布上的集中度的增加为主要特点:时间上,年降水的增加趋势以冬季1月和夏季6月降水的集中增加为主;一日降水量大于等于50mm的暴雨日数和暴雨量在1990s也有了较明显的增加.空间上,年降水、夏季降水、冬季降水的增加都以中下游区的增加为主,尤其以鄱阳湖水系、洞庭湖水系的降水增加为主.1990s长江流域春季和秋季降水的减少以5月和9月两个汛期月份的降水减少为主,除金沙江水系和洞庭湖水系等少数地区外,流域大部分地区降水呈减少趋势.上述1990s出现的降水趋势明显与近年来全球变暖背景下长江流域各地区不同的温度及水循环变异有关.     

长江流域降水变化及其趋势演变

本文对中国长江流域降水趋势进行了分析.指出对月降水量而言,20世纪后50年不同区域出现1不胃的降水趋势变化特征.趋势插补法研究表明中国降水时空分布趋势十分明显.对长江流域长期降水资料分析研究指出夏季月份降水时间更集中,而对年降水而言在一些站则表现出明显的周期变化.     

Structural features of Panarea volcano in the frame of the Aeolian Arc (Italy): Implications for the 2002–2003 unrest

Panarea, characterized by gas unrest in 2002–2003, is the volcanic island with the least constrained structure in the eastern-central Aeolian Arc (Italy). Based on structural measurements, we define here its deformation pattern relative to the Arc. The main deformations are subvertical extension fractures (63% of data), normal faults (25%) and dikes (12%). The mean orientation of the extension fractures and faults is N38°E, with a mean opening direction of N135° ± 8°, implying extension with a moderate component of dextral shear. These data, matched with those available for Stromboli volcano (pure opening) and Vulcano, Lipari and Salina volcanoes (predominant dextral motions) along the eastern-central Arc, suggest a progressive westward rotation of the extension direction and an increase in the dextral shear. The dextral shear turns into compression in the western arc. The recent unrest at Panarea, coeval to that of nearby Stromboli, may also be explained by the structural context, as both volcanoes lie along the portion of the Arc subject to extension.     

An exotic Cretaceous kimberlite linked to metasomatized lithospheric mantle beneath the southwestern margin of the Francisco Craton,Brazil

We present major and trace element compositions of mineral concentrates comprising garnet xenocrysts,ilmenite,phlogopite,spinel,zircon,and uncommon minerals (ti...     

How a court, a commissioner and a lobby group brought European transport policy to life in 1985

Until the mid-1980s, transport policy was considered by many as one of the least successful domains of the European integration project. However, from the early 1990s onwards, there are clear signs of a single European transport policy, along with the accompanying implementation of infrastructure projects. What is the explanation for such a change in pace? This paper aims to offer insight in these processes by looking at the mechanisms which form and transform this policy domain. To understand the state of a policy domain and its dynamics over time an institutional approach is taken. Two concepts in political science, ‘policy arrangements’ and ‘supranational governance’ are combined and used as a framework to analyse the European transport policy domain. This analysis describes the development of several elements: organisations, rules, the transnational society, power, resources, and the central transport discourse. It demonstrates that all of these elements have developed from an intergovernmental setting towards a more supranational one. This development was slow in the first decennia when European transport policy was rather passive, but it picked up speed in the 1980s and 1990s. In the pivotal year of 1985, pressure from the transnational society resulted in a rapid change of the rules, the resources and the discourse.     

Validation through HVSR measurements of a method for the quick detection of site amplification effects from intensity data: an application to a seismic area in Northern Italy

An instrumental validation is attempted of an innovative approach devoted to the quick individuation, from macroseismic data, of site amplification phenomena able to significantly modify seismic hazard levels expected on the basis of average propagation effects only. According to this methodology, two evaluations of hazard are performed at each investigated locality: the former, obtained by epicentral intensity data ‘reduced’ at the site through a probabilistic attenuation function and, the latter, computed by integrating such data with seismic effects actually observed at the site during past earthquakes. The comparison, for each locality, between these two hazard estimates allow to orientate the identification of those sites where local amplifications of earthquake ground motion could be significant. In order to check such methodology, indications obtained in this way from macroseismic data are compared with the estimates of transfer functions performed through the HVSR technique applied to microtremors. Results concerning municipalities located in a seismic area of Northern Italy indicate a good agreement between macroseismic and instrumental estimates.     

Ar / Ar dating of high-pressure rocks from the Ligurian Alps: Evidence for a continuous subduction–exhumation cycle

We present ³⁹Ar–⁴⁰Ar dating of phengite, muscovite and paragonite from a set of mafic and metasedimentary rocks sampled from the high-pressure (HP) metaophiolites of the Voltri Group (Western Alps) and from clasts in the basal layer conglomerates from the Tertiary molasse which overlie the high-pressure basement. The white mica-bearing rocks display peak eclogitic and blueschist-facies parageneses, locally showing complex greenschist-facies replacement textures. The internal discordance of age spectra is proportional to the chemical complexity of the micas. High-Si phengites from eclogite clasts record a ³⁹Ar–⁴⁰Ar age of ca. 49 Ma for the eclogite stage and ca. 43 Ma for the blueschist retrogression; phengites from a blueschist basement sample yield an age of ca. 40 Ma; low-Si muscovite from a metasediment dates the formation of the greenschist paragenesis at ca. 33 Ma. Our data indicate that the analyzed samples reached high-pressure conditions at different times over a time-span of c.a. 10 Ma. Subduction was continuing during exhumation and blueschist retrograde re-equilibration of higher-pressure, eclogite-facies rocks. This process kept the isotherms depressed, allowing the older HP-rocks to escape thermal re-equilibration. Our results, added to literature data, fit a tectonic model of a subduction–exhumation cycle, with different tectonic slices subducted at different times from Early Eocene until the Eocene–Oligocene boundary.