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Diagnostic features of a catastrophic aridization of climate, desertification, and paleoecological crisis in steppes of the Lower Volga region have been identified on the basis of data on the morphological, chemical, and microbiological properties of paleosols under archeological monuments (burial mounds) of the Middle Bronze Age. These processes resulted in a certain convergence of the soil cover with transformation of zonal chestnut (Kastanozems) paleosols and paleosolonetzes (Solonetz Humic) into specific chestnut-like eroded saline calcareous paleosols analogous to the modern brown desert-steppe soils (Calcisols Haplic) that predominated in this region 4300–3800 years ago.1 In the second millennium BC, humidization of the climate led to the divergence of the soil cover with secondary formation of the complexes of chestnut soils and solonetzes. This paleoecological crisis had a significant effect on the economy of the tribes in the Late Catacomb and Post-Catacomb time stipulating their higher mobility and transition to the nomadic cattle breeding.  相似文献   

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OBJECTIVE: Concordance of nutritional research priorities with the related burden of disease is essential to develop cost-effective interventions to address the nutritional problems of populations. The present study aimed to evaluate whether nutrition research priorities are in agreement with the population's nutritional problems in Latin America. DESIGN: The epidemiological profile was contrasted with the research priorities and research produced by academic institutions for each country. Qualitative analysis of research production by type of contribution to problem solving was also conducted. SETTINGS: Nine Latin American countries. RESULTS: Obesity (high body mass index (BMI)) and micronutrient deficiencies (anaemia) emerged as key problems, followed by stunting, breast-feeding/lactation and low birth weight. Wasting in children and women (low BMI) was uncommon. Concordance of ranked research priorities with the epidemiological profile of the country was generally good for nutrition-related chronic diseases, micronutrients and low birth weight, but not for undernutrition, stunting and breast-feeding. Studies on the efficacy and effectiveness of interventions were uncommon. CONCLUSIONS: The present research agenda insufficiently supports the goal of public health nutrition, which is to ensure the implementation of cost-effective nutrition programmes and policies. A more rational approach to define research priorities is needed.  相似文献   

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Sediment profiles from the floodplain of Morava River in the Czech Republic have been collected from exposed river banks (4–6 m long sections) and cores (2–4 m deep) and investigated using a set of geochemical proxies validated by granulometry and conventional geochemical analysis, outlined in our previous paper. The work was conducted to evaluate the increase in sedimentation rate during Medieval and modern time periods. Correlation of sediments along the current channel belt allows identification of two most important synchronous changes in the channel structure over the past 1300 years: in the 13th century and at the end of the 16th century. These changes could be related to central European climatic extremes rather than to land cover/land use practises. Analysis of the pollen record in peaty deposits at the floodplain edge allows excluded dramatic deforestation in Medieval times. Maps of the area from the last five centuries revealed direct and indirect signs of past avulsions and clearly show how the original multichannel system was transformed into a single meandering channel in the early 20th century. The extrapolated aggradation rate (net vertical accretion of floodplain fines except for levee sediments) increased from 0.2–0.3 cm/year in 700 AD to 0.3–0.4 cm/year in 2000 AD depending on the grain size of the sediment. This is the smallest yet reported enhancement of siliclastic deposition, although Morava River watershed has been intensively used for agriculture and its land cover has changed in a manner similar to west and central European rivers.  相似文献   

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In the First World War, the region around Ypres (West‐Flanders, Belgium) was a battlefield where millions of copper‐containing shells were fired. To investigate the consequences of this shelling, we analysed statistically data on the copper (Cu) content in the topsoil (0–0.5 m) of the province of West‐Flanders, an area of 3144 km2. The measurements had been made on the fine earth (< 2 mm) fraction of 2786 samples. A preliminary screening of the data revealed larger concentrations of Cu in a region of approximately 625 km2 around Ypres. These concentrations were estimated by ordinary block kriging on the logarithms of the Cu concentration with separate variograms for the battlefield area and the rest of the province and mapped. The median concentration in the battlefield area was 18.0 mg Cu kg?1 compared with 12.0 mg Cu kg?1 elsewhere. We conclude that the current Cu enrichment in the soil around Ypres is the legacy of the millions of shells that were fired in the First World War.  相似文献   

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Sustainability of the local shifting cultivation practice in the mountainous region of Northern Laos was investigated. Due to low fertility of the soils derived from shale and its strongly weathered and acidic nature in the eastern side of the Nam Khan River watershed, shortening of the fallow period to produce enough amount of upland rice for the local population would not be sustainable any more. On the other hand, the eroded materials from limestone range were added to the soils in the western side of watershed which made the soil more fertile. Based on the calculated population capacity by Carneiro's equation, a system with 2- or 3-year fallow for 1-year cultivation can be the maximum to afford the current population. To make the shifting cultivation system more sustainable, introduction of fallow system with a tree species, paper mulberry (Broussonetia papyrifera) could be a good option to be proposed.  相似文献   

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Twenty years ago, Desender and Turin (1989) analysed the changes in the composition of carabid beetles in four NW European countries between the periods <1950 and 1950-1985. Recently, a new distribution atlas of carabid beetles in Belgium was compiled using data collected during the period 1986-2008. In the light of the Countdown2010 target of halting the loss of biodiversity, we used these new data to test whether or not previously observed trends were altered. Since 1950, 46 species were no longer recorded in Belgium and seven species were added to the Belgian fauna. By relating the changes in distribution area to ecological and life history traits as well as to conservation priorities of the species, we examined which species characteristics were associated with the strongest changes in distribution. Comparing the period before 1950 with the period 1950-1985 showed that species from nutrient-poor dry biotopes and heathlands, threatened, rare and big species declined. Generalists, non-threatened species, species with a pan-European distribution range, species in the centre of their distribution range and common species, on the other hand, increased. From the period 1950-1985 to 1986-2008, mainly macropterous species, both rare and very common species and big species decreased, while generalists, dimorphic species, species with a pan-European distribution range and species that were already common in the second period increased. For the conservation of carabid beetles in a strongly industrialised and highly fragmented NW European landscape, we propose actions on two levels: first, the protection and adequate management of high quality biotopes, especially nutrient-poor grasslands and heathlands, in large core areas for specialist species and second, the creation and/or restoration of a ‘matrix’ that facilitates the exchange of individuals between core areas for the conservation of both generalist and specialist species.  相似文献   

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Nitrogen mineralization and nitrification in the soil of sub-alpine ruderal community of Mount Uludağ, Bursa, Turkey was measured for 1 year, under field conditions with Verbascum olympicum and Rumex olympicus being the dominant pioneer species under dry and wet sites, respectively. Seasonal fluctuations were observed in N mineralization and nitrification. The net N mineralization and nitrification were high in early summer and winter, due to high moisture. The annual net N mineralization rate (for the 0–15 cm soil layer) was higher under R. olympicus (188 kg N ha−1 yr−1) than under V. olympicum (96 kg N ha−1 yr−1). A significant positive correlation between net N mineralization and soil organic C (r2 = 0.166), total N (r2 = 0.141) and water content (r2 = 0.211) was found. Our results indicate that N mineralization rate is high in soils of ruderal communities on disturbed sites and varies with dominant species and, a difference in net N mineralization rate can be attributed to organic C, total N and moisture content of soils.  相似文献   

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Hydraulic Resistance and Capacitance in the Soil-Plant System   总被引:1,自引:0,他引:1  
In this paper, the hydraulic resistances and capacitances were evaluated. based on the development of non-(?) model of water flow in the soil-plant system and the simulating experiment work.The results show that the mean hydraulic resistance in the soil-plant system is 6.79×109 MPa·S·m-3; the mean hydraulic capacitance in the system is 5.2×107m3·MPa-1. In the components of hydraulic capacitance in the system, the capacitance in soil (81.8×10-6m3·MPa ) is the biggest and its variability with suii water potential is extremely strong, the capacitance in plant (5.3×10-7m3·MPa-1) is much smaller than that in soil, and the capacitance in shoots (15.5×10-7m3·2MPa-1) is bigger than that in roots (8.4×10-7m3·2MPa-1). An interesting result is that the capacitance in plant is almost equivalent to that in the soil-plant system.  相似文献   

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In Finland, Capercaillie (Tetrao urogallus) populations have a history of serious decrease starting from the mid-20th century. The decline is temporally in line with the expansion of modern forestry practices that created major changes in the landscape. We used tetraonid route-censuses from 18 forestry board districts and Finnish forest inventories (data on forest stand structure) to analyze the decline in 1965-1988. We used information theoretical model selection to evaluate a set of log-linear second order autoregressive models, allowing for spatially correlated process errors. The average trend throughout the country corresponded to an annual decline of 4.01% (mean of local trends) ± 0.24% (SEM), parallel to a half-life of 17 years. The decline was surprisingly uniform throughout the country (SD = 1.01%) and most parsimoniously explained by a geographically constant log-linear trend. At the large scale of observation applied here, population trends could not be explained by the proportional increase of younger forest age classes (<40 years old and <80 years old, respectively). Our analysis does not support the hypothesis that the decline in Capercaillie numbers is due to changes in the forest age structure, but we cannot exclude the possibility that other factors behind the decline may have interacted with forestry in general. From a conservation point of view, we caution against over-emphasizing the role of forest age especially at large spatial scales, but leaning also on other research, we recommend that more management efforts would go into the preservation of the overall forest cover and the original physiognomy in single forest patches.  相似文献   

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The mobility and migration capacity of Zn in the soil-plant system were studied in a series of pot experiments with barley as a test plant. The parameters of Zn accumulation depending on the metal concentrations in soils and soil solutions were estimated by soil and water culture methods. Experiments with barley in water culture were performed on a nutrient (soil) solution extracted from soddy-podzolic soil (Albic Retisol (Loamic, Ochric)) to which Zn2+ was added to reach working concentrations increasing from 0.07 to 430 μM. Different responses of barley plants to changes in the concentration of Zn in the studied soil were identified. Ranges of the corresponding concentrations in the soil and aboveground barley biomass were determined. Parameters of Zn accumulation by test plants were determined depending on the metal content in soddypodzolic soil and the soil solution. A new method was proposed for evaluating the buffer capacity of soils with respect to a heavy metal (Zn) using test plants (BCS(P)Zn). The method was used to evaluate the buffering capacity of loamy sandy soddy-podzolic soil. The considered methodological approach offers opportunities for using data obtained during the agroecological monitoring of agricultural lands with heavy metals (HMs), including the contents of exchangeable HMs and macroelements (C and Mg) in soils and concentrations of HMs and (Ca + Mg) in plants, in the calculation of the buffering capacity of the surveyed soils for HMs.  相似文献   

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Eurasian Soil Science - The accumulation of polycyclic aromatic hydrocarbons (PAHs) in plants and peat of three natural subzones—forest-tundra, southern tundra, and northern tundra—is...  相似文献   

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Bioactive compounds are used in the design and development of new food products with potential health benefits, although little is known regarding their bioavailability and interactions. This study assessed the stability, in vitro bioaccessibility, and human bioavailability of β-cryptoxanthin from β-cryptoxanthin-rich drinks with and without added phytosterols developed for this purpose. The developed drinks showed no difference in the content of β-cryptoxanthin, and they were stable over 6 months. In vitro, hydrolysis of β-cryptoxanthin esters and the amount of free β-cryptoxanthin at duodenal and micellar phases were similar regardless of the presence of phytosterols. In the human study, the daily intake provoked significant increments of β-cryptoxanthin in serum regardless of the type of the drink. In conclusion, in vitro and in vivo human studies have shown that the bioavailability of β-cryptoxanthin is not significantly affected by the presence of phytosterols when they are simultaneously supplied in a drink.  相似文献   

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Abstract

Numerous experiments have been conducted in Maryland and Pennsylvania since 1981 to determine if adding the nitrification inhibitor dicyandiamide (DCD) to an ammonium‐containing or producing N fertilizer source would increase the efficiency of that source with turfgrass, wheat, or corn. Greater yields per unit of fertilizer N were attained in three of eight experiments with wheat when DCD was included with an early spring application of N as urea or UAN. There was no significant beneficial effect of DCD on turf clipping yields or color in the 3 years of the turf study or on corn grain yields in the 22 field comparisons of N fertilizer with and without DCD. In five of the 22 comparisons with corn, there was a significantly lower grain yield with DCD than when it was not included. In three of these five cases, it was hypothesized that the lower yields with DCD were due to increased NH3 volatilization from urea or urea‐ammonium nitrate solutions containing DCD that were surface‐applied to no‐till corn. It was concluded that there was little likelihood that the inclusion of a nitrification inhibitor such as DCD with N fertilizer would increase N fertilizer efficiency with corn or turf on the predominantly well‐drained silt loam soils in the two states.  相似文献   

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This study assesses the effect of salinity in bioavailability and toxicity of Zn by means of laboratory bioassays by observing contamination in both sediment and water, accumulation of Zn in biological tissues, and histopathological damage in the gills and guts tissues of Ruditapes philippinarum clams, which were exposed to different types of sediments from the Gulf of Cádiz (SW Spain) as well as two dilutions of toxic mud coming from an accidental mining spill. With this objective, the coefficients of distribution (K D) for Zn between overlying water and sediments were calculated, the histopathological frequencies in the tissues of the gills and guts of clams were determined, and the biota-sediment bioaccumulation factors as well as the bioaccumulation factors were quantified in the different stations. Results showed that the greatest histopathological damages appeared when the salinity values decreased. Statistical results showed that salinity was inversely correlated with histopathological damage (p?<?0.01) for the lesion index for gills. The most outstanding results were observed in the two dilutions of toxic mud (0.3% and 7.9%) at a salinity value of 10. Salinity was inversely correlated with the concentration of Zn in biological tissues (p?<?0.05) and inversely correlated with the concentration of Zn in water and sediment. Zn mobilization to the overlying water is produced when salinity values decrease.  相似文献   

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The hydroponic technique using expanded clay for the production of chrysanthemum was studied for possible use by Brazilian flower producers. Eight varying nutrient solution nitrogen (N):phosphorus (P):potassium (K) ratio treatments in a randomized block configuration with four replications were used. Six of the treatments supplied the same solution over the entire experimental period. The N:P:K ratios in the nutrient solution compared were: 1.0:0.3:1.0, 1.0:0.3:1.5, 1.0:0.3:2.0, 1.0:0.3:2.5, 1.5:0.3:1.0, and 2.0:0.3:1.0. The other two treatments consisted of N:P:K ratios of 2.0:0.3:1.0 during the juvenile stage and 1.0:0.3:1.5 or 1.0:0.3:2.0 ratios during the reproductive stage. There were two or three daily irrigations depending on plant need. The electrical conductivity (EC) and pH of the nutrient solution were checked once each day and the nutrient solution was chanced when 50% depleted. The plants were crown to the two‐stem stage under 50 long and 4.0 short days. Harvest was made 115 days after plant establishment. There were not expressive differences in plant characteristics among the treatments. The 1.0:0.3:2.5 N:P:K ratio gave the highest flower numbers per stem, stem length, and fresh and dry weights per plant.  相似文献   

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The results of the studies of soil changes after the 2010 fires in the forest outliers of the city of Tolyatti have been reviewed. The morphological analysis of postpyrogenic soils has showed that the fire touched only the upper part of their profiles. It has been revealed that the surface fires favor the more intense loss of organic carbon than the crown fires (2.85 and 2.37%, respectively). However, the crown fires are more destructive for soils, because, first, they are a continuation of the surface fires and, second, sheet and linear water erosion of soils develops because of the complete denudation of the soil cover. It has been found that forest fires result in the dehumification of soils, which is related to the destruction of the organic horizons, the mineralization of root residues, and the almost complete absence of fresh plant waste on the postfire areas. The pyrogenic impact increases the portion of humic acids in the organic matter. Along with the transfer of the clay fraction, the translocation of polycyclic aromatic hydrocarbons resulting from the fires to the accumulative geochemical positions is also possible.  相似文献   

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