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481.
482.
The effects of wastewater application on electrical conductivity, water retention and water repellency of soils planted with Populus deltoides (eastern cottonwood) and irrigated with different concentrations of landfill leachate and compost wastewater, tap water and nutrient solution were evaluated. Substrate water content at field capacity (?0.033 MPa) and at permanent wilting point (?1.5 MPa) was determined with a pressure plate extractor to assess available water capacity of the substrate. A water drop penetration test was used to determine substrate water repellency. The biomass of nutrient and landfill leachate treatments was significantly (P < 0.05) greater compared to the tap water and compost wastewater treatments. All treatments increased substrate water content at field capacity and at permanent wilting point. Landfill leachate significantly increased available water capacity (up to 52%); treatment with compost wastewater significantly decreased it (25–47%). All substrates showed increased water repellency after the experiment at field capacity and permanent wilting point comparing to the original substrate. The strongest influence on water repellency at both field capacity and permanent wilting point showed irrigation with compost wastewater and tap water. Pronounced influence on substrate’s water repellency of compost wastewater could be contributed to a high content of dissolved organic carbon, whereas Mg and Ca cations caused flocculation and consequent water repellency of the substrate irrigated with tap water. The results indicate that soil physical characteristics must be closely monitored when landfill leachate and compost wastewater are used for irrigation to avoid long term detrimental effects on the soil, and consequently on the environment. Due to the complexity of the compost wastewater quality the latter should be applied on open fields only after prior pre-treatment to reduce dissolved organic carbons, or alternatively, compost wastewater should be added only intermittently and in diluted ratios. 相似文献
483.
Contact bioassays are important for testing the ecotoxicity of solid materials. However, survival and reproduction tests are often not practical due to their duration which may last for several weeks. Avoidance tests with soil invertebrates may offer an alternative or extension to the classic test batteries due to their short duration (days rather than weeks) and due to a sensitive sub-acute endpoint (behavior). The aims of our study were: (a) to evaluate the effects of three solid industrial wastes (incineration ash, contaminated wood chips and contaminated soil) on three Oligochaeta species (enchytraeids Enchytraeus albidus, Enchytraeus crypticus and earthworm Eisenia fetida) in avoidance tests; (b) to compare the sensitivity among the species and to compare results of avoidance test to reproduction tests; (c) to elucidate if measuring the weight in the earthworm avoidance test could be reasonable additional endpoint. Avoidance mostly increased with the increasing percent of waste in the mixture showing a dose–response curve. E. fetida was the most sensitive species and E. crypticus the least one. An additional endpoint, (changes in weight after two-day exposure) was not found to be more sensitive than avoidance reaction, but it confirmed that earthworms staying in the highest concentrations of the waste mixture were affected showing apparent weight reduction. Our results indicate that avoidance tests with earthworms and enchytraeids are feasible for waste testing. 相似文献
484.
485.
Adam Dušek Luděk Bartoš František Sedláček 《Behavioral ecology and sociobiology》2011,65(12):2209-2217
The issue of adaptive adjustment of offspring sex ratio (proportion of male births) in polytocous mammals, producing several
offspring per litter, is controversial because females of these species can maximize their fitness mainly by adjusting offspring
number. To address this issue, we examined the effect of maternal condition at mating, experimentally decreased by pre-mating
food restriction, on the sex ratio variation in 137 female mice. We tested two basic sex allocation hypotheses plausible for
polytocous mammals: (1) the Myers hypothesis, predicting that cheaper sex should be favored in poor environmental conditions
to maximize offspring number; and (2) the Williams hypothesis, predicting maximum fitness returns by adjusting size- and sex-specific
composition of the litter according to the maternal condition. The food-restricted mothers produced larger litters with a
higher proportion of cheaper daughters than the control mothers. By contrast, the control mothers optimized size and sex composition
of the litter according to their weight at mating. In addition, the offspring of the food-restricted mothers suffered less
from pre-weaning mortality than those of the control mothers. Therefore, when comparing the groups, the Myers hypothesis had
a general significance while the Williams hypothesis was plausible only for the control mothers. Furthermore, some of the
food-restricted mothers partly coped with the pre-mating food restriction and increased the proportion of sons in the litter
with the increasing maternal weight loss (during the period of food restriction). The sex ratio variation was thus a result
of three sex allocation strategies depending on the maternal condition at mating. 相似文献
486.
Marek Špinka Gudrun Illmann Jiří Haman Petr Šimeček Jitka Šilerová 《Behavioral ecology and sociobiology》2011,65(7):1447-1457
In domestic pigs, about 20% of nursing episodes end without milk transfer (non-nutritive nursings, NNNs). The function of
NNNs has not been satisfactorily explained yet. Here, we suggest that NNNs may be a part of an honest signaling system that
enables the sow to provide more frequent nutritive nursings (NNs) to those litters that can prove their need through exceptionally
frequent milk ejection solicitations. We further propose that the system is kept stable through the accelerating costs attached
to the solicitation in the form of NNNs. Based on this hypothesis, we predicted that (P1) with an increasing number of all
nursings (ALL = NNNs + NNs) the number of NNs should increase and that (P2) with an increasing number of ALL the proportion
of NNNs should increase. We tested P1 and P2 using a meta-analysis applied to data from eight studies that recorded the number
of NNs and NNNs in domestic pigs. We confirmed both P1 (NNs increasing with ALL) and P2 (proportion of NNNs increasing with
ALL). In combination, these results show a steeply accelerating cost of each additional nutritive nursing that piglets instigate.
This cost sets limits to the piglets' ability to solicit higher maternal investment through more frequent nursing solicitations. 相似文献
487.
Maja Zupančič Justin Nastja Pajk Vesna Zupanc Marija Zupančič 《Waste management (New York, N.Y.)》2010,30(6):1032-1042
A pot experiment is described with a fast-growing poplar clone and two native willows (Populus deltoides Bartr. cl. I-69/55 (Lux)), Salix viminalis L. and Salix purpurea L.), irrigated with landfill leachate and compost wastewater over a 1-year growing period. The use of leachate resulted in up to 155% increased aboveground biomass compared to control water treatments and in up to 28% reduced aboveground biomass compared to a complete nutrient solution. The use of compost wastewater resulted in up to 62% reduced aboveground biomass compared to the control treatments and in up to 86% reduced aboveground biomass compared to the complete nutrient solution. Populus was the most effective in biomass production due to the highest leaf production, whereas S. purpurea was the least effective in biomass accumulation, but less sensitive to high ionic strength of the irrigation water compared to S. viminalis. The results showed a high potential for landfill leachate application (with up to 2144 kg N ha?1, 144 kg P ha?1, 709 kg K ha?1, 1010 kg Cl ha?1, and 1678 kg Na ha?1 average mass load in the experiment). High-strength compost wastewater demonstrated less potential for application as irrigation and fertilization source even in high water-diluted treatments (1:8 by volume). 相似文献
488.
D. Ugarković B. Kurelec S. Krča R. Batel A. Robitzki W. E. G. Müller H. C. Schröder 《Marine Biology》1990,107(2):191-197
The siliceous spongeGeodia cydonium Jameson was used to study the influence of pollution in marine environments on selected parameters of the intracellular signal transduction pathway. The parameters chosen were: intracellular distribution of protein kinase C (PK-C),ras-gene expression and DNA polymerasealpha (DNA Polalpha) activity. Both PK-C andras-gene product (ras-protein) have previously been established to be key molecules in the intracellular signalling pathway in sponges; increased level ofras-protein mediates events following sponge cell-cell contact. Three unpolluted and three polluted sites in the off-shore seawater around Rovinj (Yugoslavia) were selected for the study in 1989. The state of pollution of these sites has been well-defined in a series of previous studies (1976 to 1989). Transplantation of regenerating sponge cubes ofG. cydonium to the polluted sites resulted in pronounced changes in the parameters chosen, compared to controls exposed to unpolluted environments. Expression ofras gene was increased by three- to five-fold after exposure of regenerating sponge tissue to the impacted sites. At the site with the highest pollutional load,ras mRNA level was about 50% of that at the reference sites. In parallel experiments it was established that, in response to pollution, a translocation of PK-C from the cytosolic to membrane fraction occurred. At the most impacted site, most of the enzyme activity was cytosolic. DNA Polalpha-activity, as a measure of sponge cell proliferation, decreased in a pollutioncorrelated manner. Our results indicate that the intracellular signalling system within sponge cells is activated in response to moderate pollution but is depressed in heavily polluted environments. 相似文献
489.
Reserves, resilience and dynamic landscapes 总被引:3,自引:0,他引:3
Bengtsson J Angelstam P Elmqvist T Emanuelsson U Folke C Ihse M Moberg F Nyström M 《Ambio》2003,32(6):389-396
In a world increasingly modified by human activities, the conservation of biodiversity is essential as insurance to maintain resilient ecosystems and ensure a sustainable flow of ecosystem goods and services to society. However, existing reserves and national parks are unlikely to incorporate the long-term and large-scale dynamics of ecosystems. Hence, conservation strategies have to actively incorporate the large areas of land that are managed for human use. For ecosystems to reorganize after large-scale natural and human-induced disturbances, spatial resilience in the form of ecological memory is a prerequisite. The ecological memory is composed of the species, interactions and structures that make ecosystem reorganization possible, and its components may be found within disturbed patches as well in the surrounding landscape. Present static reserves should be complemented with dynamic reserves, such as ecological fallows and dynamic successional reserves, that are part of ecosystem management mimicking natural disturbance regimes at the landscape level. 相似文献
490.
The paper presents the studies on equilibrium trapping of organic air pollutants. A piece of a commercial capillary chromatographic column coated with polydimethylsiloxane was used for trapping. This kind of the trap was applied for sampling and enrichment of selected volatile nonpolar organic compounds from workplace atmosphere (woodworking shop). In the method developed, which is based on equilibrium trapping the concentration of analytes in a studied medium can be calculated from the partition coefficients determined in a calibration step and the amount of particular analytes trapped. Simultaneously with equilibrium trapping, analytes were sampled into sorbent packed tubes. The concentrations of analytes in woodworking shop atmosphere obtained with both sampling methods (equilibrium and dynamic) were in good agreement. 相似文献