The influence of a city on element contents of a terrestrial moss (Hylocomium splendens)

Forty terrestrial moss (Hylocomium splendens) samples were collected along a 120-km-long south-north transect running through Norway's largest city Oslo. Concentrations of 29 chemical elements (Ag, Al, Au, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, Pt, S, Sb, Sr, Th, Ti, and Zn) and values for loss on ignition (475 degrees C) are reported. Silver (Ag), Al, Au, Bi, Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Pt, Sb, Th, Ti, and Zn all show a characteristic Oslo peak when element concentrations are plotted against location of the sample site along the transect. Gold (Au) and Pt show the greatest relative enrichment of all elements in the city (ca. 10x "background"). Titanium (Ti), which is related to local minerogenic dust rather than anthropogenic emissions, shows a significant peak in Oslo. Loss on ignition, a measure of the amount of organic material in a sample, shows a negative peak in Oslo and at sites close to a known dust source. Input of fine dust thus appears to dominate many of the observed element concentrations in moss. The concentrations of Na are clearly influenced by the input of marine aerosols and show decreasing concentrations from south (near Oslo Fjord) to north (inland). The major plant nutrients Ca, K, Mg, P and S, as well as Hg, are the few elements displaying no spatial dependency along the transect. Element concentrations reach background variation levels at a distance of 20-40 km from the city centre.     

The influence of macrophytes on sedimentation and nutrient retention in the lower River Spree (Germany)

Nutrient retention due to sedimentation in running waters has been little studied. The knowledge about the processes of self-purification is important for the management of rivers. The principal aim of our investigations was to quantify nutrient retention by sedimentation within and adjacent to stands of submerged macrophytes. In addition, we examined the relationship between deposition and sedimentation patterns and the flow regime. In the summer of 2001, investigations were performed in the lower River Spree with sediment traps and sediment cores and measurement of flow velocities. The spatial distribution of macrophytes was described and related to sedimentation and flow patterns. Water and sediment samples were analysed for total phosphorus and total organic nitrogen concentrations. Macrophytes significantly enhanced water residence time by factors between 2 and 18. Trapping rates were high within and downstream of macrophyte stands due to the prevailing quiescent conditions. Trapping rates were low in regions not covered by macrophytes, where flow velocities were high. Calculated deposition of organic matter due to trapping rates accounted for 15-49% of observed deposition between May and September, the vegetation period. The difference between calculated and observed deposition can partly be attributed to an incomplete erosion of the organic sediments between October and April. Between May and September, nitrogen and phosphorus were retained by deposition by as much as 2.5% and 12.2%, respectively (% of total load). Therefore, macrophytes considerably contributed to total monthly phosphorus retention (up to 25%) by increasing deposition of particulate organic matter.     

Element dynamics of oak ecosystems on acid-sulphurous mine soils in the Lusatian lignite mining district (Eastern Germany)

Seepage water chemistry and input–output budgets of major ions are investigated within an oak chronosequence (Quercus petraea Liebl., 3 years; Quercus rubra L., 26 and 37 years) on acid-sulphurous soils of lignite mining. Due to declining intensity of weathering and deep percolation, the leaching rates of Fe, Al, Mn, Mg, Ca, NH₄ and SO₄-S from soil decline drastically within 34 years. Moreover, an enrichment of NH₄-N, NO₃-N, PO₄-P and K can be noticed, resulting from the accumulation of living biomass.     

A Pb isotope and trace element study of rainwater from the Massif Central (France)

Lead isotope ratios and Zn, Pb, Cu, Cd, Sb and Rb contents were measured in samples of rainwater collected over a period of 15 months from the Massif Central (France). Each sample, collected automatically at monthly intervals, represents a series of rainfall events. Rainwater chemistry was interpreted in terms of the chemical contributions from wet deposition and from different source regions for dust in the centre of France. Trace element concentrations in rainwater samples showed a wide range, particularly for Pb (1.30-465 microg/l), with variations decreasing for Cd (0.07-1.70 microg/l), Zn (1.00-54.00 microg/l), Cu (0.20-25.00 microg/l), Sb (approximately 0-0.33 microg/l) and Ni (approximately 0-15.00 microg/l). Trace element contents do not correlate with rainfall amount and no inter-element correlations are evident in the data. Lead is the most common trace metal found in the rainwater (mean value = 996 microg/m2/y) while Sb is the least common element measured (mean value = 1.12 microg/m2/y). The composition of rainwater collected from the Massif Central shows a range in Pb isotope ratios from 17.935 to 19.22 (206Pb/204Pb), 15.578 to 15.73 (207Pb/204Pb) and 37.559 to 38.606 (208Pb/204Pb). A five-component mixing model involving contributions from the natural background, gasoline inputs from industrial and agricultural activity and a source resulting from mining waste may be used to explain both the Pb isotope signature and the fluctuations in trace metal contents of Massif Central rainwater.     

Stable isotopes of bulk organic matter to trace carbon and nitrogen dynamics in an estuarine ecosystem in Babitonga Bay (Santa Catarina, Brazil)

The biogeochemical processes affecting the transport and cycling of terrestrial organic carbon in coastal and transition areas are still not fully understood. One means of distinguishing between the sources of organic materials contributing to particulate organic matter (POM) in Babitonga Bay waters and sediments is by the direct measurement of δ¹³C of dissolved inorganic carbon (DIC) and δ¹³C and δ¹⁵N in the organic constituents. An isotopic survey was taken from samples collected in the Bay in late spring of 2004. The results indicate that the δ¹³C and δ¹⁵N compositions of OM varied from − 21.7‰ to − 26.2‰ and from + 9.2‰ to − 0.1‰, respectively. δ¹³C from DIC ranges from + 0.04‰ to − 12.7‰. The difference in the isotope compositions enables the determination of three distinct end-members: terrestrial, marine and urban. Moreover, the evaluation of source contribution to the particulate organic matter (POM) in the Bay, enables assessment of the anthropogenic impact. Comparing the depleted values of δ¹³C_DIC and δ¹³C_POC it is possible to further understand the carbon dynamic within Babitonga Bay.     

Bryophytes as indicators of trace metals pollution in the River Brenta (NE Italy)

The performance of aquatic bryophytes for detecting metal pollution was tested along the River Brenta, in NE Italy. Nine sampling sites were selected, three of them along short tributaries with no anthropic influence upstream, the others along the main bed of the river. Two sites were deliberately placed downstream from a previously known pollution focus. The multivariate analysis (classification and ordination) of the matrix of 10 metals and 38 samples revealed: (i) a good discrimination between 'clean' and potentially polluted sites; (ii) two contamination syndromes, one by As and, to a lesser degree, Pb, and the other by Cr, due to agricultural and industrial activities, respectively; and (iii) the previously known pollution focus was clearly detected. The magnitude of contamination was estimated by means of a comparison between local backgrounds and concentrations of metals measured. The distance of aquatic bryophytes from the center of the river was negatively correlated with metal concentrations, which suggests that this factor should be taken into account in the implementation of sampling protocols.     

The shear strain influence on the dynamics of thin-walled beams

The influence of middle-surface shear strains on the dynamics of thin-walled beams is analyzed. By means of a suitable choice of the axial displacement field, shear lag effects in bending and torsion are taken into account for open and closed cross-sections. The equations of motion are obtained via Hamilton's principle. The flexural-torsional natural frequencies in the presence of warping which varies along the beam axis are compared with those given by Timoshenko-Vlasov models. The solution to the problem is pursued by means of the most natural choice, i.e. the classical trigonometric series expansion. A suitable algorithm is developed to solve the resulting eigenvalue problem which turns out to be strongly ill-conditioned.     

Selection of sustainable projects for floodplain restoration and urban wastewater management at the lower Chubut River valley (Argentina)

Urban growth causes environmental degradation of extended areas at the coastal floodplain of the Chubut River (Argentina). We developed procedures to identify environmentally sustainable engineering projects for floodplain restoration and urban wastewater management. We addressed specific questions about considering basic hydrological knowledge, stakeholders’ interests and social acceptance, and evaluated scoring methods that would be consistent, non-redundant and robust to various weighting criteria. Our procedures followed the following steps: (1) identification of sustainability paradigms adapted to local contexts; (2) development of hydrological modeling and collection of expert and stakeholders’ judgment in order to formulate a wide palette of feasible project alternatives; (3) development of a set of indicators of environmental sustainability to evaluate the project alternatives and test of their self-consistency; (4) evaluation of the proposed projects by means of a hierarchical multivariate analysis, estimation of the indicator weights through multivariate analyses of the un-weighted judgment scores, and reduction of the redundancy incurred during project evaluation. Finally, we identified a small set of highly ranked project alternatives to achieve floodplain restoration and sustainable urban wastewater management in the area and tested the obtained ranks for sensitivity and robustness to eventual bias in the estimation of environmental scores. We discuss the methodological developments presented in this study and their eventual application to similar landscape and urban planning scenarios.     

The effects of dissecting tools on the trace element concentrations of fish and mussel tissues

A comparison of the effects of dissecting tools composed of various materials on the trace element content of the muscle of the marine bluefish, Pomatomus saltatrix, and the soft tissues of freshwater mussels, Eliptio complanatus and Lampsilus radiata, is presented. The fish were dissected with blades made of stainless steel, Lexan plastic, titanium, and Teflon-coated stainless steel. The mussels were dissected with stainless and Teflon tools only. Elements measured included As, Cd, Cr, Cu, Hg, Ni, Pb, Se, Sn, Te, V, and Zn. Significant concentration differences (P = 0.01) were not found for any element in fish or mussel samples dissected by the different tools.     

Lichen (Xanthoria parietina) biomonitoring of trace element contamination and air quality assessment in Pisa Province (Tuscany, Italy)

In the northern part of Pisa Province (Tuscany, Italy), the use of lichens as both airborne trace element biomonitors and air quality bioindicators is described. The following elements were analysed in Xanthoria parietina: As, Cd, Cr, Ni, Pb, V, Zn and Hg, and the results are compared with those we previously obtained in Livorno Province (Tuscany) using the same lichen species. The results identify spots of different environmental metal contamination and air quality. Median values of Pb, V and Ni concentrations were much lower than those of Livorno Province, with maximum values even nine times lower. Arsenic contamination was also lower, while Cd, Hg and Zn levels were similar in the two areas. In Pisa Province, the highest levels of contamination were recorded for Zn, Pb, Cr and Ni, and a degree of agreement was found between air quality and metal concentrations in lichens. The air quality in Pisa Province is better than in Livorno Province, even if the different climatic and orographic features of the two areas may influence the presence of lichen species and thus an assessment of air quality.     

海河大桥横隔梁有限元分析

以海河大桥为工程实例,探讨了横隔梁的结构安全性,运用ANSYS建立了实体单元进行模拟,得出了横隔梁的应力分布规律,以了解其力学行为,为横隔梁的配筋提供依据。     

火灾动力学的应用（下）

(续上期 )5　露天火灾的行为　　最简单的火灾是露天条件下的火灾 ,它既不受墙壁的影响 ,也不受顶棚的影响。露天的火灾被视为自由燃烧的火灾 ,一般是受燃料控制的。在这种火灾的正上方 ,炽热气体和燃烧产物的气流柱可升至空气之中。该气流柱称之为羽流 ,它形成一个倒锥形柱体。图 3所示为不受顶棚和墙壁限制的稳定燃烧的露天火灾。这种情况既可代表户外火灾 ,也可代表分区内的小火灾 (此时它尚未成长到已受限于分区边界和通风洞口的规模 )。在稳定条件下 ,羽流相对于火灾中心线是对称的。炽热气体因浮力而上升的作用会导致周围的空气在火灾…     

The spatial and temporal trends of Cd, Cu, Hg, Pb and Zn in Seine River floodplain deposits (1994-2000)

Fresh floodplain deposits (FD), from 11 key stations, covering the Seine mainstem and its major tributaries (Yonne, Marne and Oise Rivers), were sampled from 1994 to 2000. Background levels for Cd, Cu, Hg, Pb, and Zn were established using prehistoric FD and actual bed sediments collected in small forested sub-basins in the most upstream part of the basin. Throughout the Seine River Basin, FD contain elevated concentrations of Cd, Cu, Hg, Pb and Zn compared to local background values (by factors>twofold). In the Seine River Basin, trace element concentrations display substantial downstream increases as a result of increasing population densities, particularly from Greater Paris (10 million inhabitants), and reach their maxima at the river mouth (Poses). These elevated levels make the Seine one of the most heavily impacted rivers in the world. On the other hand, floodplain-associated trace element levels have declined over the past 7 years. This mirrors results from contemporaneous suspended sediment surveys at the river mouth for the 1984-1999 period. Most of these temporal declines appear to reflect reductions in industrial and domestic solid wastes discharged from the main Parisian sewage plant (Seine Aval).     

The influence of lightweight aggregate concrete element chimneys on the airtightness of wood-frame houses

Energy efficient buildings must be constructed as airtight as possible. In Norway the airtightness requirements have become stricter. This leads to a growing interest for airtight constructions and methods. Element chimneys of lightweight aggregate concrete, LWAC, are widely used in Norway. Air leakages are frequently observed in connection with these chimneys. The leaks are found either through the element, as a result of insufficient surface treatment of the air permeable element, or through the joint with the roof. This article discusses the influence that LWAC element chimneys can have on the airtightness of wood-frame houses. This is done by measurements and calculations. The influence of the sealing method used in the joint with the roof and the influence of the surface treatment of the LWAC elements on the airtightness is investigated. The results show that even the simplest sealing in the joint with the roof is adequate because of the limited circumference of the LWAC chimney. The results also show that the airtightness provided by the surface treatment of the chimney is very sensitive to the workmanship. If the workmanship is thorough, the influence of a LWAC element chimney on the airtightness of a wood-frame house should be negligible.     

干旱条件下微肥对羊草生长的影响

针对西北干旱区优质饲草料不足、水资源缺乏等问题,以中科1号羊草人工草地为研究对象,在干旱区自然降雨条件下探讨不同微肥对羊草生长发育的影响.结果表明:拔节期配施微肥可增加羊草干草产量,增产效果为硼(B)>铁(Fe)>锰(Mn)>钼(Mo)>锌(Zn),其中施用B和Fe肥分别较单施氮磷肥(CK)增产11.8%和11.2%;施用Fe和Mn肥使羊草叶片长度分别增加4.9%、13.5%.施用B肥后穗数增加8.5%,穗长增加28.6%,种子产量均增加17.5%,施用微肥亦可增加羊草粗蛋白含量,其中Fe、Mo肥增加幅度最大,较CK分别增加4.52%和3.14%.拔节期增施B肥可显著提高羊草干草产量和种子产量,建议干旱区推广应用.     

Spatial and temporal dynamics of suspended load at-a-cross-section: the lowermost Ebro River (Catalonia, Spain)

Suspended load dynamics were analyzed for the period 2007-2009 in a semi-meandering cross-section under different hydrological conditions. Samples were collected at four different points of the cross-section. During “low discharges” (≤600 m³/s) suspended load samples were collected at-a-monthly basis, whereas at “high discharges” (>600 m³/s) sampling was conducted intensively (at-a-daily basis during the first stages of the flood event). Results indicated that during low discharges, both organic and inorganic suspended load concentrations tended to be uniformly distributed across the fluvial section; but during high discharges, two distinct areas were found: an area extending from the “Inner-bank” to the “Channel centre” (Area-I) with higher suspended concentrations (organic and inorganic) than those recorded in the “Outer bank” (Area-II). This phenomenon was likely related to the formation of secondary flow velocity cells and the activation of new sources of sediment. In addition, a non-significant relationship between organic suspended load and water flow was observed in the outer-bank. At-a-monthly basis, the analysis of the suspended load showed the existence of an intra-annual cycle of the inorganic concentrations, with a progressive increase from October to March followed by a decrease from March to September. Nevertheless, the organic suspended load did not show any trend, being equally distributed along the year, suggesting that other sources of organic matter besides phytoplankton are predominant.     

相邻基坑相互影响二维有限元分析

以国内某市典型的两个相邻深基坑同时开挖的工程为例,使用Midas/GTS4.2.0有限元分析软件建立平面模型模拟出了两基坑同时开挖时的相互影响关系,得出了两基坑在开挖过程中的变形、支护结构体系的受力变化以及位移趋势。     

Ecological and geochemical evaluation of ecosystems of the Curonian Spit (Russia)

ABSTRACT

This paper presents the results of the quantitative content of metals (Cu, Zn, Pb, Mn, Sr, Ni, Ca, Fe, Br, Rb) in the leaves of the flora dominants of the main ecosystems of the Curonian Spit (foredune, palve area, large dune ridge). The heavy metal content in the upper layer of sandy soils, forest ecosystems (palve area) and large dune ridge was analysed. In the accumulative horizon of soils, the heavy metal content did not exceed the sanitary standards (MAC (maximum allowable concentration)/TAC (tentative allowable concentration)), and their concentration was significantly lower than the similar level in urbanised territories which allows for taking their contents into account as a baseline for the Kaliningrad region. From the ecological and physiological points of view, the content of heavy metals in the studied plants is not toxic, and is typical of the accumulation features in plants.