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Heavy metals distribution in agricultural topsoils in urban area 总被引：24，自引：0，他引：24
Intensive urbanisation of the Croatian capital of Zagreb has led to a situation where very good agricultural soils, developed mostly on Pleistocene eolian sediments and alluvial and proluvian Holocene sediments are entrapped within urban and suburban areas. Therefore the influence of urban and industrialised environments on the accumulation of metals in agricultural topsoils has been investigated. On an area of 860 km2 of the wider Zagreb region, 331 samples were taken according to a regular 1ǵ km square mesh. Samples were dissolved in aqua regia and analysed for Cd, Cu, Fe, Mn, Ni, Pb and Zn with flame atomic aqua regia absorption spectroscopy. The following concentration ranges have been determined: Cd 0.25-3.85 mg kg-1 (average 0.66 mg kg-1), Cu 4.30-183 mg kg-1 (average 20.8 mg kg-1), Fe 5.8-51.8 g kg-1 (average 27 g kg-1), Mn 79.2-1282 mg kg-1 (average 613 mg kg-1), Ni 0.70-282 mg kg-1 (average 49.5 mg kg-1), Pb 1.50-139 mg kg-1 (average 25.9 mg kg-1), and Zn 15.2-277 mg kg-1 (average 77.9 mg kg-1). Visualisation of the spatial data is made by the aid of GIS, and selected maps of the heavy metal concentrations in topsoils are displayed. Statistical multivariate analysis was carried out for quantitative study and data were processed by means of R-mode factor analysis, applying the varimax-raw rotational technique. F1, which grouped Cd, Pb, Cu, Zn and partially Ni, is characterized as a factor with strongly scattered anthropogenic influence. The elements in F2, Fe, Mn and partially Ni are mainly of geogenic, i.e. pedogenic, origin. The variations in concentrations of the investigated elements are thus of both natural and anthropogenic origins. The variations in the main soil constituents, particularly Fe and Mn, are determined primarily by the composition of different regolithic substrates of the fluvial origin in recent pedogenesis. High concentrations of nickel are also related to morphogenetic characteristics of the wider region, primarily basic and ultrabasic magmatic rocks of the surrounding mountain range. It is, however, assumed that the anomalous nickel concentrations in the vicinity of the highway and the airport are of anthropogenic origin, i.e. caused by fuel combustion. Copper is characterized by strongly scattered anthropogenic influence, which is related particularly to uncontrolled solid waste disposals or discharges of liquid waste from households or agricultural enterprises. With Zn, Pb and Cd, there are two possible ways of diffuse pollution. The Sava River, which drains the area and feeds the abundant Quaternary aquifer spreading below the major part of the investigated agricultural areas, has been exposed to intensive pollution by mining, industry and cities in the recent history. The part of the area with the highest determined concentrations of Zn, Pb and Cd was repeatedly flooded as recently as the previous decade; therefore, the recent sedimentation of the river deposits exposed to pollution is a very probable cause of the accumulation of metals in this until recently inundation area. The other way is atmospheric deposition of particles from urban sources (industrial emission, traffic, waste disposals, heating plants, etc.). In addition to agricultural enterprises, several economically important, but ecologically risky, facilities are situated in the vicinity of the water-protection area. The area is intersected by a very busy ring road, while a marshalling yard, the city dump, pharmaceutical and chemical industry, the district-heating plant and the airport are all located in close proximity. The geochemical maps show a clear relationship between human activities and metal concentration gradients. 相似文献
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Mesozooplankton spatial distribution and community structure in the South Adriatic Sea during two winters (2015, 2016) 
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下载免费PDF全文 Whereas the data on mesozooplankton in the epipelagic offshore Mediterranean Sea are extensive, less information is available about plankton in the deeper layers. The present study aims to describe the vertical and horizontal structure and distribution of mesozooplankton species and their associations down to 1,200 m in the water of the Southern Adriatic Sea. Zooplankton were sampled using a Nansen net of 200‐μm mesh size during two cruises in the winters of 2015 and 2016, extending from the coast to the open sea. In total, 203 zooplankton taxa were identified. The community was dominated by copepods, representing between 67% and 91% of the total abundance. The highest total densities were recorded in the upper layers where a high proportion (up to 36%) of appendicularians was also observed in the first sampled year. Five groups of samples were determined based on their community structure. In 2015 communities were distinct between the 0 and 50 m layer and the underlying one (50–100 m), whereas in 2016 epipelagic waters were inhabited by a more uniform mesozooplankton community. The mesopelagic and deep‐water fauna, especially copepods, showed a relatively stable composition in both sampling years Overall, our study confirms the oligotrophic character of the Southern Adriatic, with occasional density outbreaks of appendicularians under favourable conditions. 相似文献
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The lysosomal membrane destabilization and the metallothionein content in the digestive gland cells of mussels (Mytilus galloprovincialis Lam.), collected along the east coast of the North Adriatic (Istrian and Kvarnerine coast, Croatia), were examined over a period of four years (1996–1999). The lysosomal membrane stability, as a biomarker of general stress, showed that the membrane labilization period in mussels from polluted, urban- and industrial-related areas was significantly decreased (p<0.05) when compared to mussels from control, clean sea water sites. In the harbour of Rijeka, the most contaminated site, the lysosomal membrane stability was reduced by more than 70% compared to the control. This method also proved to be a useful biomarker for detection of additional stress caused by short-term hypoxia that occurred once during this study inside the polluted and periodically quite eutrophic Pula Harbour. The concentration of metallothioneins in the mussel digestive gland, as a specific biomarker of exposure to heavy metals, did not reveal significant differences (p<0.05) between sites covered by this study. 相似文献
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Hyunjin Jeong Martin Bureau Sukyoung K. Yi Davor Krajnovi&#; Roger L. Davies 《Monthly notices of the Royal Astronomical Society》2007,376(3):1021-1032
We present Galaxy Evolution Explorer ( GALEX ) far-ultraviolet (FUV) and near-ultraviolet (NUV) imaging of the nearby early-type galaxy NGC 2974, along with complementary ground-based optical imaging. In the ultraviolet, the galaxy reveals a central spheroid-like component and a newly discovered complete outer ring of radius 6.2 kpc, with suggestions of another partial ring at an even larger radius. Blue FUV–NUV and UV-optical colours are observed in the centre of the galaxy and from the outer ring outwards, suggesting young stellar populations (≲1 Gyr) and recent star formation in both locations. This is supported by a simple stellar population model which assumes two bursts of star formation, allowing us to constrain the age, mass fraction and surface mass density of the young component pixel by pixel. Overall, the mass fraction of the young component appears to be just under 1 per cent (lower limit, uncorrected for dust extinction). The additional presence of a nuclear and an inner ring (radii 1.4 and 2.9 kpc, respectively), as traced by [O iii ] emission, suggests ring formation through resonances. All three rings are consistent with a single pattern speed of 78 ± 6 km s−1 kpc−1 , typical of S0 galaxies and only marginally slower than expected for a fast bar if traced by a small observed surface brightness plateau. This thus suggests that star formation and morphological evolution in NGC 2974 at the present epoch are primarily driven by a rotating asymmetry (probably a large-scale bar), despite the standard classification of NGC 2974 as an E4 elliptical. 相似文献
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