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1.
2.
Soils from two typical tidal salt marshes with varied salinity in the Yellow River Delta wetland were analysed to determine possible effects of salinity on soil carbon sequestration through changes in soil microbiology. The mean soil respiration (SR) of the salt water–fresh water mixing zone (MZ) was 2.89 times higher than that of the coastal zone (CZ) (4.73 and 1.63?μmol?m?2?s?1, respectively, p?.05), and soil dehydrogenase activity was the main microbial factor influencing SR. In addition to the higher soil microbial biomass, the MZ had more β-Proteobacteria than the CZ, as well as some specific bacteria with strong heterotrophic metabolic activity such as Pseudomonas sp. and Limnobacter sp. that might have led to its higher dehydrogenase activity and respiratory rates. Additionally, the CZ possessed more Halobacteria and Thaumarchaeota with the ability to fix CO2 than the MZ. Significantly lower soil salinity in MZ (4.25?g?kg?1) was suitable for β-Proteobacteria, but detrimental for Halobacteria compared with CZ (7.09?g?kg?1, p?.01), which might lead to the lower microbial decomposition capacity of soils in CZ. As a result, the CZ has a higher soil organic carbon content than the MZ. 相似文献
3.
Comprehensive temperature monitoring in an in-vessel forced-aeration static-bed composting process 总被引:6,自引:0,他引:6
Masafumi Tateda Le Duc Trung Nguyen Viet Hung Michihiko Ike Masanori Fujita 《Journal of Material Cycles and Waste Management》2002,4(1):62-69
Comprehensive temperature monitoring was done in an in-vessel forced-aeration static-bed composting process using sewage sludge.
The three layers that divided the compost pile horizontally showed different temperature distributions. The temperature of
the top layer appeared not to be influenced by the ambient temperature. The temperature of the center area of the top layer
was taken to be the representative temperature for evaluating composting start-up performance. The temperature of the bottom
layer was strongly influenced by the ambient temperature, and the temperature of the center area of the bottom layer was taken
to be the representative temperature for pathogen control as it was the minimum temperature in the reactor. Composting start-up
performance was influenced by several factors when the ambient temperature was either below or above 20°C. When the ambient
temperature was below 20°C, the time taken to reach 65°C (T
65) was influenced by the temperature of inflowing air, but when the temperature was higher than 20°C, it was influenced by
the ratio of sewage sludge to seed compost (F/S). T
65 was least when F/S was 1–2.
Received: January 9, 2001 / Accepted: October 10, 2001 相似文献
4.
Benjamin P. Louis Pierre-Alain Maron Valérie Viaud Philippe Leterme Safya Menasseri-Aubry 《Environmental Chemistry Letters》2016,14(3):331-344
Industrial agriculture is yearly responsible for the loss of 55–100 Pg of historical soil carbon and 9.9 Tg of reactive nitrogen worldwide. Therefore, management practices should be adapted to preserve ecological processes and reduce inputs and environmental impacts. In particular, the management of soil organic matter (SOM) is a key factor influencing C and N cycles. Soil microorganisms play a central role in SOM dynamics. For instance, microbial diversity may explain up to 77 % of carbon mineralisation activities. However, soil microbial diversity is actually rarely taken into account in models of C and N dynamics. Here, we review the influence of microbial diversity on C and N dynamics, and the integration of microbial diversity in soil C and N models. We found that a gain of microbial richness and evenness enhances soil C and N dynamics on the average, though the improvement of C and N dynamics depends on the composition of microbial community. We reviewed 50 models integrating soil microbial diversity. More than 90 % of models integrate microbial diversity with discrete compartments representing conceptual functional groups (64 %) or identified taxonomic groups interacting in a food web (28 %). Half of the models have not been tested against an empirical dataset while the other half mainly consider fixed parameters. This is due to the difficulty to link taxonomic and functional diversity. 相似文献
5.
对紫外分光光度法测定海水中石油类浓度进行了不确定度评定。通过对标准溶液、标准工作曲线拟合、前处理过程等影响测定结果的不确定度分量进行分析,计算出测定结果的扩展不确定度,并找出影响该不确定度的主要因素。结果表明,紫外分光光度法测定海水中石油类浓度的不确定度的主要来源是实验中前处理过程的不确定度,本次实验所测海水中石油类浓度的不确定度报告为19.98±1.326 mg/L。 相似文献
6.
The objective of this study was to compare the effects of repeated field applications of three urban compost amendments and one farmyard manure amendment over a 9-year period on aggregate stability in a silty loam soil initially characterized by low clay and initial organic matter contents and poor aggregate stability. Three different aggregate stability tests with increasing disruptive intensities (fast wetting > mechanical breakdown > slow wetting tests) and different disaggregation mechanisms, were used. All of the amendments, which were applied at approximately 4 Mg C ha−1 every other year, increased the organic carbon content and improved the stability of the aggregates against the disruptive action of water, as determined by each of the stability tests. However, the year-to-year variations in the aggregate stability that related to factors other than the organic inputs were greater than the cumulative increase in aggregate stability relative to the control. The positive effects of the tested amendments on aggregate stability were linked to their contribution to soil organic C contents (r = 0.54 for the fast wetting test and r = 0.41-0.42 for the mechanical breakdown and slow wetting tests; p < 0.05). The addition of urban composts had a larger positive effect on aggregate stability than farmyard manure at the majority of sampling dates. The addition of biodegradable immature compost, such as municipal solid waste (MSW), improved the aggregate stability through an enhanced resistance to slaking. The addition of mature composts, such as the co-compost of sewage sludge and green wastes (GWS) or biowaste compost (BW), improved the aggregate stability by increasing interparticular cohesion. The MSW compost was the most efficient in improving aggregate stability during the first 6 years of the experiment (average improvements of +22%, +5% and +28% in the fast wetting, mechanical breakdown and slow wetting tests, respectively, compared to the control treatment); this result was likely due to the larger labile organic pool of the MSW compost that was highly effective at stimulating soil microbial activity. After the first 6 years, the two other composts, GWS and BW, became more efficient (average improvements of +25%, +61% and +33% in the fast wetting, mechanical breakdown and slow wetting tests, respectively, compared to the control treatment), which was probably linked to the greater increase in soil organic C contents. Therefore, the application of urban compost to silty soil that is susceptible to water erosion was effective at improving aggregate stability and thus could be used to enhance the resistance of soil to water erosion. 相似文献
7.
8.
Farmers’ perceptions of climate variability and barriers to adaptation: lessons learned from an exploratory study in Vietnam 总被引:2,自引:0,他引:2
Hoa Le Dang Elton Li Johan Bruwer Ian Nuberg 《Mitigation and Adaptation Strategies for Global Change》2014,19(5):531-548
Southeast Asian countries are confronting climate variability, challenging agricultural sustainability and rural livelihoods. However, little research effort has been devoted to exploring how farmers in those countries perceive climate variability and how the perceptions link to adaptive responses. This paper deploys information from three focus group discussions with 30 male farmers; and six in-depth interviews with one female and five male agricultural officers in the Mekong Delta, Vietnam. Recorded 34-year meteorological data in the delta from 1978 to 2011 is also incorporated to demonstrate the actual climate variability of the region. We find that farmers are becoming increasingly conscious of local climate variability issues. However, they have limited understanding of the importance of adaptation to their livelihoods. They also have limited knowledge of where and who to contact for appropriate climate change adaptation information. No opinions about the link between global warming and local climate variability and change were observed. Casual observation via public media and personal experience dominated farmers’ sources of information. Barriers to farmers’ adaptation are not exclusively restricted to socio-economic factors and resource constraints; e.g. land tenure, technical knowledge, market, social relationship, credit, information, health care, and demographics. Maladaptation, habit, and the perception of the importance of climate variability and adaptation are found as additional constraints. Observed differences in farmers’ and agricultural officers’ perspectives regarding barriers to farmers’ adaptation suggest important policy implications. 相似文献
9.
Philippe Louâpre Stéphanie Llopis Véronique Martel Joan van Baaren 《Die Naturwissenschaften》2014,101(11):875-882
In many insect species, sperm-depleted males (SDMs, i.e. males that have exhausted their sperm after a given number of matings) remain sexually active and continue to mate females. Here, we investigated the behavioural modifications that occur in both sexes of the parasitoid Asobara tabida Nees (Hymenoptera: Braconidae), after matings by fertile males and sperm-depleted males. We show that (i) virgin females, mated females and females mated to a SDM exhibited different behaviours and that (ii) males responded differently to females depending on whether the females had previously mated with an SDM or not. Our findings demonstrate that SDM influenced the reproductive behaviour of both males and females, especially with regard to male responsiveness and female attractiveness. These findings are discussed in the context of adaptive behaviour and fitness maximization in both males and females. 相似文献
10.
Bioaerosol sampling by a personal rotating cup sampler CIP 10-M 总被引:1,自引:0,他引:1
Görner P Fabriès JF Duquenne P Witschger O Wrobel R 《Journal of environmental monitoring : JEM》2006,8(1):43-48
High concentrations of bioaerosols containing bacterial, fungal and biotoxinic matter are encountered in many workplaces, e.g. solid waste treatment plants, waste water treatment plants and sewage networks. A personal bioaerosol sampler, the CIP 10-M (M-microbiologic), has been developed to measure worker exposure to airborne biological agents. This sampler is battery operated; it is light and easy to wear and offers full work shift autonomy. It can sample much higher concentrations than biological impactors and limits the mechanical stress on the microorganisms. Biological particles are collected in 2 ml of liquid medium inside a rotating cup fitted with radial vanes to maintain an air flow rate of 10 l min(-1) at a rotational speed of approximately 7,000 rpm. The rotating cup is made of sterilisable material. The sampled particles follow a helicoidal trajectory as they are pushed to the surface of the liquid by centrifugal force, which creates a thin vertical liquid layer. Sterile water or another collecting liquid can be used. Three particle size selectors allow health-related aerosol fractions to be sampled according to international conventions. The sampled microbiological particles can be easily recovered for counting, incubation or further biochemical analysis, e.g., for airborne endotoxins. Its physical sampling efficiency was laboratory tested and field trials were carried out in industrial waste management conditions. The results indicate satisfactory collection efficiency, whilst experimental application has demonstrated the usefulness of the CIP 10-M personal sampler for individual bioaerosol exposure monitoring. 相似文献