The contribution of organic and mineral colloidal nanoparticles to element transport in a podzol soil     

Inge C. Regelink  Liping Weng  Willem H. van Riemsdijk 《Applied Geochemistry》2011

The aim of this work is to analyze the size-distribution and composition of nanoparticles in a water-extract of a podzol B horizon. AsFlowFFF coupled to ICP–MS and a UV/VIS detector was used for particle fractionation and simultaneous measurement of the composition of the nanoparticles. Detected nanoparticles were organic and mineral particles; the mineral particles were dominated by clay and Fe-(hydr)oxides. Both organic- and inorganic particles contributed to the mobility of Fe, Al, trace metals and P. For Zn, Pb and P respectively 73%, 92% and 72% of the colloidal concentrations were associated with clay minerals. The large contribution of clay particles to the mobility of trace metals and P can be partly explained by the high amount of dispersed clay due to drying, sieving and rewetting of the soil. Inorganic nanoparticles can contribute significantly to the mobility of metals and P in soils.  相似文献   

昆虫多样性：一个被忽略的全球性重要问题     

邹怡  冯金朝  薛达元  桑卫国  Jan AXMACHER 《资源与生态学报(英文版)》2011,(4):380-384

昆虫不仅是世界上最多的物种,同时也对生态系统功能和全球经济有着十分重要的作用。因此,昆虫多样性的保护对全球来说都有着十分重要的意义。然而,昆虫多样性常被＂生物多样性＂研究者们所忽略, 昆虫多样性与植物、气候变化的关系更是不明确。本文对将来昆虫多样性的研究方向提出了几点建议,基于中国北部两大典型的森林生态系统——东北长白山地区和华北东灵山地区。这两大地区的植被和气候已经有长期并且完整的调查,而对于其中昆虫多样性的了解却不多。因此在这两个地区开展研究认识昆虫多样性格局和进一步分析昆虫和植物的关系具有重要的科学和应用价值。  相似文献   

Food web flows through a sub-arctic deep-sea benthic community     

E. Gontikaki  D. van Oevelen  K. Soetaert  U. Witte 《Progress in Oceanography》2011,91(3):245-259

The benthic food web of the deep Faroe–Shetland Channel (FSC) was modelled by using the linear inverse modelling methodology. The reconstruction of carbon pathways by inverse analysis was based on benthic oxygen uptake rates, biomass data and transfer of labile carbon through the food web as revealed by a pulse-chase experiment. Carbon deposition was estimated at 2.2 mmol C m⁻² d⁻¹. Approximately 69% of the deposited carbon was respired by the benthic community with bacteria being responsible for 70% of the total respiration. The major fraction of the labile detritus flux was recycled within the microbial loop leaving merely 2% of the deposited labile phytodetritus available for metazoan consumption. Bacteria assimilated carbon at high efficiency (0.55) but only 24% of bacterial production was grazed by metazoans; the remaining returned to the dissolved organic matter pool due to viral lysis. Refractory detritus was the basal food resource for nematodes covering ∼99% of their carbon requirements. On the contrary, macrofauna seemed to obtain the major part of their metabolic needs from bacteria (49% of macrofaunal consumption). Labile detritus transfer was well-constrained, based on the data from the pulse-chase experiment, but appeared to be of limited importance to the diet of the examined benthic organisms (<1% and 5% of carbon requirements of nematodes and macrofauna respectively). Predation on nematodes was generally low with the exception of sub-surface deposit-feeding polychaetes that obtained 35% of their energy requirements from nematode ingestion. Carnivorous polychaetes also covered 35% of their carbon demand through predation although the preferred prey, in this case, was other macrofaunal animals rather than nematodes. Bacteria and detritus contributed 53% and 12% to the total carbon ingestion of carnivorous polychaetes suggesting a high degree of omnivory among higher consumers in the FSC benthic food web. Overall, this study provided a unique insight into the functioning of a deep-sea benthic community and demonstrated how conventional data can be exploited further when combined with state-of-the-art modelling approaches.  相似文献   

A comparison of the evolution of arc complexes in Paleozoic interior and peripheral orogens: Speculations on geodynamic correlations     

J. Brendan Murphy  Cees R. van Staal  William J. Collins 《Gondwana Research》2011,19(3):812-827

We discuss the potential geodynamic connections between Paleozoic arc development along the flanks of the interior (e.g. the Iapetus and Rheic) oceans and the exterior Paleopacific Ocean. Paleozoic arcs in the Iapetus and Rheic oceanic realms are preserved in the Appalachian–Caledonide and Variscan orogens, and in the Paleopacific Ocean realm they are preserved in the Terra Australis Orogen. Potential geodynamic connections are suggested by paleocontinental reconstructions showing Cambrian–Early Ordovician contraction of the exterior ocean as the interior oceans expanded, and subsequent Paleozoic expansion of the exterior oceans while the interior oceans contracted. Subduction initiated in the eastern segment of Iapetus at ca. 515 Ma and Early to Middle Ordovician orogenesis along the flanks of this ocean is highlighted by arc–continent collisions and ophiolite obductions. Over a similar time interval, subduction and orogenesis took place in the exterior ocean and included formation of the Macquarie arc in the Tasmanides of Eastern Australia and the Famatina arc and correlatives in the periphery of the proto-Andean margin of Gondwana. Major changes in the style of subduction (from retreating to advancing) in interior oceans occurred during the Silurian, following accretion of the peri-Gondwanan terranes and Baltica, and closure of the northeastern segment of Iapetus. During the same time interval, subduction in the Paleopacific Ocean was predominantly in a retreating mode, although intermittent episodes of contraction closed major marginal basins. In addition, however, there were major disturbances in the Earth tectonic systems during the Ordovician, including an unprecedented rise in marine life diversity, as well as significant fluctuations in sea level, atmospheric CO₂, and ⁸⁷Sr/⁸⁶Sr and ¹³C in marine strata carbonates. Stable and radiogenic isotopic data provide evidence for the addition of abundant mantle-derived magma, fluids and large mineral deposits that have a significant mantle-derived component. When considered together, the coeval, profound changes in the style of tectonic activity and the disturbances recorded in Earth Systems are consistent with the emergence of a superplume during the Ordovician. We speculate that the emergence of a superplume triggered by slab avalanche events within the Iapetus and Paleopacific oceans was associated with the establishment of a new geoid high within the Paleopacific regime, the closure of the interior Rheic Ocean and the amalgamation of Laurussia and Gondwana, which was a key event in the Late Carboniferous amalgamation of Pangea.  相似文献   

Quantitative assessment of landslide hazard along transportation lines using historical records   总被引：2，自引：1，他引：1  

Pankaj Jaiswal  Cees J. van Westen  Victor Jetten 《Landslides》2011,8(3):279-291

In this paper, a quantitative landslide hazard model is presented for transportation lines, with an example for a road and railroad alignment, in parts of Nilgiri hills in southern India. The data required for the hazard assessment were obtained from historical records available for a 21-year period from 1987 to 2007. A total of 901 landslides from cut slopes along the railroad and road alignment were included in the inventory. The landslides were grouped into three magnitude classes based on the landslide type, volume, scar depth, and run-out distance. To calculate landslide hazard, we estimated the total number of individual landslides per kilometer of the (rail) road for different return periods, based on the relationship between past landslides (recorded in our database) and triggering events. These were multiplied by the probability that the landslides belong to a given magnitude class. This gives the hazard for a given return period expressed as the number of landslides of a given magnitude class per kilometer of (rail) road. The relationship between the total number of landslides and the return period was established using a Gumbel distribution model, and the probability of landslide magnitude was obtained from frequency–volume statistics. The results of the analysis indicate that the total number of landslides, from 1- to 50-year return period, varies from 56 to 197 along the railroad and from 14 to 82 along the road. In total, 18 hazard scenarios were generated using the three magnitude classes and six return periods (1, 3, 5, 15, 25, and 50 years). The hazard scenarios derived from the model form the basis for future direct and indirect landslide risk analysis along the transportation lines. The model was validated with landslides that occurred in the year 2009.  相似文献   

Modelling thermal transients from magmatic underplating—an example from the Vøring margin (NE Atlantic)     

Magnus Wangen  Rolf Mjelde  Jan Inge Faleide 《Computational Geosciences》2011,15(4):771-788

The thermal impact of several kilometre-thick magmatic underplating in the lower continental crust is studied with analytical and numerical methods. Simple analytical solutions are derived for the thermal transient in the case of an infinite depth below the underplate and also for the case of a finite depth (down to the asthenosphere). It is shown that these solutions lead to simple approximations for when the transient surface heat flow is at its maximum, what the maximum is, and for how long the transient lasts. Even though these solutions assume that the underplate is emplaced instantaneously, they are useful in the interpretation of underplating over finite time spans. A numerical scheme is suggested for the modelling of underplating that handles both short time intervals as well as long intervals. The scheme treats magmatic underplating in a mass and energy conservative manner, and it is compared against the analytical solutions. Finally, the analytical and numerical results for thermal transients are applied to a transect from the Vøring margin (NE Atlantic), with respect to various degrees of early Cenozoic magmatic intrusion. It appears that more than half of the lower crustal body (LCB) in the Vøring margin must be magmatic underplating for the vitrinite reflectance to be substantially higher than for the non-magmatic case, where the LCB is assumed to comprise Caledonian crust.  相似文献   

Rainfall-induced landslide event of May 2010 in the eastern part of the Czech Republic   总被引：3，自引：2，他引：1  

Tom��? P��nek  Rudolf Br��zdil  Jan Klime?  Veronika Smolkov��  Jan Hradecky  Pavel Zahradn��?ek 《Landslides》2011,8(4):507-516

More than 150 landslides originated in the eastern part of the Czech Republic (region of the Flysch Outer Western Carpathians—hereinafter, OWC) due to soil saturation caused by antecedent precipitation and long lasting and intensive rainfalls on 16–18 May 2010 (>300 mm as measured by some stations). As a consequence, a multitude of small failures originated 88% of which was smaller than 10⁴ m². Most landslides are characterised as shallow (<10 m) or middle–deep (10–30 m) incipient (rather short travel) landslides, debris slides and soil slips spatially clustered to a geological domain underlain by rather weak thin-bedded flysch and unconsolidated Quaternary deposits. An exception to this is represented by a kilometre-long rockslide (∼2–3 mil m³) affecting tectonically weakened and weathered claystone/mudstone-dominated flysch on the southern slope of Mt. Girová (the Beskydy Mountains). The rockslide is one of the largest long runout landslides in the territory of the Czech Republic activated over the past few decades as it reaches the dimensions of the largest documented Holocene long runout landslides in the Czech part of the OWC. A majority of the May 2010 landslide events developed inside older (Holocene or historic) landslide terrains, which points to their spatial persistency and recurrent nature. In spite of the fact that the May 2010 landslide event was not as destructive as some previous landslide activisation in the OWC region (e.g. July 1997 event), it left many slope failures at the initial stage of their potential future reactivation.  相似文献   

Seasonal variability in somatic and reproductive investment of the bivalve Scrobicularia plana (da Costa, 1778) along a latitudinal gradient     

Sílvia Santos  Joana F.M.F. Cardoso  Célia Carvalho  Pieternella C. Luttikhuizen  Henk W. van der Veer 《Estuarine, Coastal and Shelf Science》2011

Monthly investment in soma and gonads in the bivalve Scrobicularia plana is described for three populations along its distributional range: Minho estuary, Portugal; Westerschelde estuary, The Netherlands and Buvika estuary, Norway. Seasonal cycles in body mass (BMI), somatic mass (SMI) and gonadal mass (GMI) indices were observed for all populations. In Portugal, BMI and SMI peaked in mid-autumn, while in The Netherlands both indices were at their highest in mid-spring. Norway showed a different pattern with two distinct peaks: one in mid-autumn and a second peak in spring. GMI reached maximum values in July in Portugal and Netherlands and in June in Norway. Overall, mean BMI and SMI were lower in Portugal while mean GMI was lower in Norway. The spawning period lasted the whole summer in Portugal, but was shorter (only two months) in The Netherlands and Norway. The reproductive investment in The Netherlands was significantly higher than in Portugal and Norway, with the lowest values being observed in Norway. Differences in annual cycles between populations were attributed to environmental factors, namely temperature and food availability. Temperature seems important in shaping the reproductive pattern with more northern populations showing shorter reproductive periods starting later in the year, and a lower reproductive output. In addition, winter water temperatures can explain the lower mean body and somatic mass values observed in Portugal. Food availability influenced the physiological performance of the species with peaks in somatic mass coinciding with phytoplankton blooms. This relation between physiological performance and environmental factors influences S. plana distribution, densities and even survival, with natural consequences on its commercial importance.  相似文献   

Trust relationships between fishers and government: New challenges for the co-management arrangements in the Dutch flatfish industry     

Birgit I. de Vos  Jan P.M. van Tatenhove 《Marine Policy》2011

Until the 1990s fisheries were largely managed by the state. Since then, Dutch government and the sector increasingly recognized that a fishing industry cannot be managed effectively without the cooperation and participation of fishers to formulate policy and to implement and enforce laws and regulations. As a result, in the nineties, the existing neo-corporatist arrangement was replaced by a co-management system in the Dutch flatfish fishery. Co-management is often seen as leading to greater procedural legitimacy and subsequently compliance. However, constructing an effective co-management arrangement is not only a matter of building institutions but also a matter of building trust relations between the government and industry. Institutional arrangements such as co-management can contribute to these trust building processes; however, a too strong reliance on institutional arrangements can lead to distrust when new challenges are being faced and institutional arrangements fail to adapt to these changes.  相似文献   

The role of international environmental instruments in enhancing transboundary marine protected areas: An approach in East Africa     

José Guerreiro  Aldo Chircop  David Dzidzornu  Catarina Grilo  Raquel Ribeiro  Rudy van der Elst  Ana Viras 《Marine Policy》2011

The increasing degradation of marine ecosystems has led to multiple calls for greater protection through the establishment of marine protected areas (MPAs). If created at the ecosystem or ecoregion level, MPAs will likely straddle maritime boundaries and therefore necessitate international cooperation. International environmental law and international law of the sea may facilitate cooperation between States in creating transboundary MPAs. The extent to which this body of law is actually or potentially useful for the establishment of transboundary MPAs is examined in the context of the East African Marine Ecoregion, focusing on Mozambique, South Africa, and Tanzania. A general survey and assessment of the applicable global, regional, and bilateral instruments in relation to the three States is conducted. Although some global instruments are relevant in the East African context, regional and bilateral instruments are more conducive to the establishment of transboundary MPAs. The article concludes that although a trilateral agreement between Mozambique, South Africa, and Tanzania would be an ideal vehicle for the establishment of a transboundary network of MPAs addressing both national and ecoregional conservation interests, a separate solution at each border will be the first step towards this goal.  相似文献