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981.
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983.
Britt-Marie Svensson Lennart M?thiasson Tobias Akeson Anders Persson 《Waste management & research》2006,24(3):260-268
Sludge from gullies, on two types of streets with different traffic intensity, was investigated using two recommended EU methods for leachability testing of waste: a two-stage batch test and an up-flow percolation test. The main purpose of this investigation was to gain more knowledge about these leaching test methods to be able to make future decisions on the general applicability of the proposed tests. A number of parameters were determined in the sludge as well as in the eluates obtained from the two leaching tests. These include pH, conductivity, dissolved organic carbon and inorganic ions as chloride ions. A number of metals as Cd, Cr, Cu, Hg, Ni and Zn, were determined by inductive coupled plasmamass spectrometry and organic compounds were screened by high performance liquid chromatography-diode array UV detection and gas chromatography-mass spectrometry. It was found that the concentrations of metals and organic compounds in the sludge were several orders of magnitudes higher than the actual eluate concentrations. For all metals the concentrations were well below the proposed limit values for non-hazardous waste included in the Council decision document 2003/33/EC. Generally, concentrations obtained in batch test were equal or higher than from percolation tests. The repeatability of the percolation and the batch test were in average 28 and 17%, respectively. 相似文献
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986.
The architecture of vertical aerial orb webs may be affected by spider size and gravity or by the available web space, in
addition to phylogenetic and/or developmental factors. Vertical orb web asymmetry measured by hub displacement has been shown
to increase in bigger and heavier spiders; however, previous studies have mostly focused on adult and subadult spiders or
on several size classes with measured size parameters but no mass. Both estimations are suboptimal because (1) adult orb web
spiders may not invest heavily in optimal web construction, whereas juveniles do; (2) size class/developmental stage is difficult
to estimate in the field and is thus subjective, and (3) mass scales differently to size and is therefore more important in
predicting aerial foraging success due to gravity. We studied vertical web asymmetry in a giant orb web spider, Nephila pilipes, across a wide range of size classes/developmental stages and tested the hypothesis that vertical web asymmetry (measured
as hub displacement) is affected by gravity. On a sample of 100 webs, we found that hubs were more displaced in heavier and
larger juveniles and that spider mass explained vertical web asymmetry better than other measures of spider size (carapace
and leg lengths, developmental stage). Quantifying web shape via the ladder index suggested that, unlike in other nephilid
taxa, growing Nephila orbs do not become vertically elongated. We conclude that the ontogenetic pattern of progressive vertical web asymmetry in
Nephila can be explained by optimal foraging due to gravity, to which the opposing selective force may be high web-building costs
in the lower orb. Recent literature finds little support for alternative explanations of ontogenetic orb web allometry such
as the size limitation hypothesis and the biogenetic law. 相似文献
987.
Vesna Zupanc Martina ŠturmSonja Lojen Nina Marši?-KacjanJoseph Adu-Gyamfi Branka Bra?i?-?eleznikJanko Urbanc Marina Pintar 《Agriculture, ecosystems & environment》2011,144(1):167-174
In the search for new technologies that would ensure optimum yield and environmental sustainability, various irrigation, nitrogen and cropping system management strategies for the production of vegetables with a shorter growing period were assessed at a benchmark site in Slovenia for the years 2006 and 2007. In the studied years four irrigation and fertilization treatments were applied: (1) 50% drip irrigation of plants water requirements ETcrop and the farmer's practice of fertilisation (broadcasting), (2) fertilisation and 100% drip irrigation (fertigation), (3) the farmer's practice of irrigation (sprinkler irrigation using water stored in plastic tanks) and fertilisation, and (4) control (the farmer's practice of irrigation but no fertilisation). An equivalent of 80, 80 and 200 kg ha−1 of nitrogen (N), 50, 50 and 80 kg ha−1 of phosphorous (P) and 120, 120 and 300 kg ha−1 of potassium (K) was added for iceberg lettuce, endive and cabbage, respectively. Nitrogen (N) labelled fertilizer (15N) was applied to trace the movement of the applied N fertiliser. The tested irrigation and fertilisation techniques for the production of vegetables with a shorter growing period in the Slovenian climate showed that environmentally sustainable practices (split application of nutrients compared to broadcast incorporating fertilisation) should be a practice of choice in water protection zones. The results confirm that fertigation and improved irrigation scheduling can be an effective way of minimizing nitrate leaching, and should be considered for vegetable production in or close to groundwater protection zones. 相似文献
988.
Ji?í Dole?al Zuzana MaškováJan Lepš Daniela SteinbachováFrancesco de Bello Jitka KlimešováOliver Tackenberg František ZemekJan Květ 《Agriculture, ecosystems & environment》2011,145(1):10-28
Oligotrophic mountain meadows are threatened biodiversity hotspots throughout Europe. The traditional summer hay-making followed by autumn grazing is no longer economic and question is whether alternative managements can maintain both plant species and functional diversity typical of these habitats. In the Bohemian Forest Mts., we applied three treatments (mowing once a year - i.e., cutting and removing the biomass, mulching once a year - cutting and leaving the crushed biomass to decompose in situ, fallowing - no cutting) in order to assess temporal changes in meadow vegetation, plant trait composition and biomass production in a 13-year experiment. We recorded for each species twenty-five traits as to be most informative of plant strategies related to growth, resource acquisition and carbon-water economy. We compared different components of trait composition (community averages that mostly reflect traits of dominant species vs. the Rao index of functional diversity that reflects trait dissimilarity among species) and their impact on biomass production. We show that mulching promotes species and functional diversity by facilitating heliophilous forbs and legumes with more acquisitive strategies in resource use and release, e.g., higher foliar N and P content. This occurs at the expense of tall grasses (with resource-retentive strategies, e.g., high leaf dry matter content) which dominate the mown and fallow plots. The divergence in most quantitative traits indicates that niche complementarity is the dominant assembly process in mulched plots, which can prevent competitive exclusion and enable species coexistence. The divergent development was detected only after 5-6 years. This slow floristic and functional response is caused by acidity of soil and severe mountain climate that preclude rapid responses of vegetation to land-use changes. We conclude that mulching represents a good compromise maintaining both plant species and functional diversity as well as a relatively high biomass production. Mowing without grazing leads to gradual nutrient loss and thus reduces the productivity and diversity in these oligotrophic ecosystems. Fallowing causes gradual loss in diversity by increased grass competition and litter accumulation. 相似文献
989.
Ian?H.?RowlandsEmail author 《Mitigation and Adaptation Strategies for Global Change》2011,16(7):749-773
This article analyses the debate associated with the ancillary impacts of climate change mitigation options in developing
countries, with a particular focus upon Africa’s 34 least developed countries. While these countries’ emissions of greenhouse
gases are relatively small (and they do not have emission limitation commitments in the current international regime), inattention
to the mitigation agenda would mean that developing countries both miss potential funding opportunities and fail to ‘climate-proof’
their development strategies. A focus, therefore, upon the short-term, local, developmental impacts that serve to change the
relative attractiveness of different mitigation options from the perspective of the developing country is in these countries’
current strategic interests. In this article, I examine three energy-related climate change mitigation options: improved cookstoves,
carbon-free electricity and improved energy efficiency in industry. Key ancillary impacts are better indoor air quality, better
outdoor air quality and job creation (respectively). Further work to strengthen the evidence base regarding these impacts
needs to be undertaken, potentially drawing upon broader work that has already been completed. Thus, in conclusion, a call
for cross-fertilisation of information between heretofore disparate research communities is made. Additionally, the development
of an integrated research agenda, forging linkages among cookstoves, indoor air quality and climate change mitigation research
communities in Africa’s least developed countries, is identified as a priority. 相似文献
990.
Tomoyoshi?HirotaEmail author Kazuei?Usuki Masaki?Hayashi Manabu?Nemoto Yukiyoshi?Iwata Yosuke?Yanai Tomotsugu?Yazaki Satoshi?Inoue 《Mitigation and Adaptation Strategies for Global Change》2011,16(7):791-802
In the northernmost region of Japan (Hokkaido Island), earlier onsets of thick snowcover in recent years (post 1980) have
reduced the penetration depth of soil frost, resulting in over-winter survival of unharvested small potato (Solanum tuberosum) tubers that emerge as weeds in the spring in rotation crop fields. To prevent the occurrence of potato weeds, a method was
developed to manipulate soil-frost depths by artificially controlling snowcover thickness, guided by a simple numerical model
that simulates soil freezing-thawing processes using daily mean air temperature and snowcover thinckness as input variables.
The method involves removal of snowcover to expose the soil surface in the beginning of winter until the soil freezes to a
sufficient depth. After that time, snow is deposited back or allowed to accumulate naturally to prevent further penetration
of frost, which may cause undesirable delay in the seeding of spring crops. Field trials indicated that the model predicted
frost depths within several centimeters of observed values, when measured temperature and snowcover thickness were used as
model input. Based on the field and laboratory data, a soil temperature of −3°C is necessary for complete elimination of potato
tubers. To achieve this temperature in potato-burial zones without causing excessive freezing, an optimal frost depth is 0.3
to 0.4 m. The method is being adopted by progressive potato producers in the region, who use tractor-mounted snow ploughs
to manipulate snowcover over a large scale. This is an emerging new technology for agricultural adaptation to climate variability. 相似文献