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1.
The analysis of odor components in livestock waste has been extensively studied. Past research has identified volatile fatty acids, especially from C3 to C6, as indicators of malodor. Originally, the odorous components were analyzed by gas chromatography after a tedious absorption and troublesome extraction procedure or by a subjectively olfactory system or sense of smell. Thus, there is a need for the development of highly specific, quantitative analytical methods. In this research, a comprehensive liquid manure analysis approach-capillary electrophoresis (CE) with a systematic optimization procedure-was adopted to measure the concentration of propanoic acid (C2H5COOH, C3), butyric acid (C3H7COOH, C4), valeric acid (C4H9COOH, C5) and caproic acid (C5H11COOH, C6) in swine manure. Liquid samples after filtration were injected into CE directly. The following condition is finally proposed: fused-silica capillary, effective length 40 cm, 50 microm I.D.; buffer, 20 mM Tris and 10 mM p-anisate, pH 8.0; voltage 30 kV; temperature 25 degrees C. The results showed that CE provided a quantitative analysis of volatile fatty acids in liquid manure at the ppm level with minimum sample needed (nanoliter). Moreover, the use of CE is a timesaving technique; one measurement for the separation of those VFAs could be completed within 10 min. 相似文献
2.
Karley Campbell Ilkka Matero Christopher Bellas Thomas Turpin-Jelfs Philipp Anhaus Martin Graeve Francois Fripiat Martyn Tranter Jack Christopher Landy Patricia Sanchez-Baracaldo Eva Leu Christian Katlein C. J Mundy Sren Rysgaard Letizia Tedesco Christian Haas Marcel Nicolaus 《Ambio》2022,51(2):318
Sea ice continues to decline across many regions of the Arctic, with remaining ice becoming increasingly younger and more dynamic. These changes alter the habitats of microbial life that live within the sea ice, which support healthy functioning of the marine ecosystem and provision of resources for human-consumption, in addition to influencing biogeochemical cycles (e.g. air–sea CO2 exchange). With the susceptibility of sea ice ecosystems to climate change, there is a pressing need to fill knowledge gaps surrounding sea ice habitats and their microbial communities. Of fundamental importance to this goal is the development of new methodologies that permit effective study of them. Based on outcomes from the DiatomARCTIC project, this paper integrates existing knowledge with case studies to provide insight on how to best document sea ice microbial communities, which contributes to the sustainable use and protection of Arctic marine and coastal ecosystems in a time of environmental change.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01658-z. 相似文献
3.
One of the major reasons for desertification is unrestricted grazing leading to vegetation depletion, soil erosion and degradation, phenomena often considered irreversible in the short term. Here, we compare soil and biological parameters of degraded and conserved, recently rehabilitated arid shrubland in the Northern Negev, Israel. The study area was restored by conservation efforts including a strictly controlled grazing regime initiated in 1992. The visually recognizable improvement in the ecology of the restored shrubland is reflected in significant improvement in all examined biotic (herbaceous biomass, shrub patch density, and insect activity), and soil parameters (nutrients, organic matter content, moisture, and water infiltration). The difference is created predominantly by restoration of large biological patches composed of shrubs and other perennial plants often associated with ant or termite nests, where the most significant increases in productivity and soil quality were observed. In the conserved shrubland such patches covered 35 or 25 % of the area (in a normal and a drought year, respectively). In the degraded shrubland 5 % or less of the area was occupied by such patches that were much smaller and of lower biological complexity. With respect to plant biodiversity, six plant species were found only—and 18 others became significantly more common—in the rehabilitated area. The results of this article indicate that functional arid drylands can be restored within <16 years relying on strict conservation management with reduced grazing intensity. 相似文献
4.
The disadvantages of developed biological nutrient removal (BNR) processes (additional energy for liquid circulation and addition of external carbon substrate for denitrification in anoxic zones) were improved by reconfiguring the process into (1) an anaerobic zone followed by multiple stages of aerobic-anoxic zones (TNCU3 process) or (2) anaerobic, oxic, anoxic, oxic zones in sequence (TNCU2 process). These two pilot plants were operated at a recycling sludge ratio of 0.5 without internal recycle of nitrified supernatant. The sludge retention time was maintained at 10 d. The main objective of this study is to analyze the kinetics of different microorganisms in these two processes and A2O process by using the Activated Sludge Model No. 2d. The effective removal efficiency of carbon, total phosphorus and total nitrogen at 87-98%, 92-100% and 63-80%, respectively, were achieved in the testing runs. According to model simulations, the microbial kinetics in the TNCU3 and TNCU2 processes would be affected by different operations. When the step feeding strategy was adopted, the HRT was longer due to the less influent flowrate in the front stages and the microbes would grow in quantities by about 6% in the aerobic reactors. In the followed anoxic reactors, the microbes would decrease in quantities by about 12% due to the dilution effect. The dilution effects in TNCU3 and TNCU2 processes did not take place in A2O process because the recycling mixed liquid from the aerobic reactor to the anoxic reactor still contained particulate components. The XH, XPAO, and XAUT concentrations in the effluent of the last tank were lower when the step-feeding mode was adopted. The TNCU3 and TNCU2 processes could be operated efficiently without nitrified liquid circulation and addition of external carbon substrate for denitrification. 相似文献
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6.
The activated sludge process is the most common method of secondary municipal wastewater treatment; solids retention time (SRT) is the key control parameter for this process. Typically, operating at long SRT is considered only for nitrification, but there are additional benefits of high SRT operation. This paper presents experimental and literature evidence to demonstrate three major additional benefits of long SRT operation: increased oxygen transfer efficiency; improved biomass particle size distribution, which results in more efficient clarification with fewer effluent particles and suspended solids; and enhanced removal of many emerging contaminants such as pharmaceuticals, personal care products, and endocrine disrupting compounds. This paper presents experimental results from several treatment plants that showed increasing oxygen transfer efficiency and particle size with increasing SRT, and evidence documenting improved removal of emerging contaminants and biodegradable organic carbon. A long-term survey of three treatment plants concludes that operating at higher SRT is not as energy intensive as typically assumed. 相似文献
7.
Refuge sharing network predicts ectoparasite load in a lizard 总被引:1,自引:0,他引:1
Stephan T. Leu Peter M. Kappeler C. Michael Bull 《Behavioral ecology and sociobiology》2010,64(9):1495-1503
Living in social groups facilitates cross-infection by parasites. However, empirical studies on indirect transmission within
wildlife populations are scarce. We investigated whether asynchronous overnight refuge sharing among neighboring sleepy lizards,
Tiliqua rugosa, facilitates indirect transmission of its ectoparasitic tick, Amblyomma limbatum. We fitted 18 neighboring lizards with GPS recorders, observed their overnight refuge use each night over 3 months, and counted
their ticks every fortnight. We constructed a transmission network to estimate the cross-infection risk based on asynchronous
refuge sharing frequencies among all lizards and the life history traits of the tick. Although self-infection was possible,
the network provided a powerful predictor of measured tick loads. Highly connected lizards that frequently used their neighbors’
refuges were characterized by higher tick loads. Thus, indirect contact had a major influence on transmission pathways and
parasite loads. Furthermore, lizards that used many different refuges had lower cross- and self-infection risks and lower
tick loads than individuals that used relatively fewer refuges. Increasing the number of refuges used by a lizard may be an
important defense mechanism against ectoparasite transmission in this species. Our study provides important empirical data
to further understand how indirectly transmitted parasites move through host populations and influence individual parasite
loads. 相似文献
8.
Remedial Process Optimization and Ozone Sparging for Petroleum Hydrocarbon‐Impacted Groundwater 下载免费PDF全文
A former natural gas processing station is impacted with total petroleum hydrocarbons (TPH) and benzene. Remedial process optimization (RPO) was conducted to evaluate the effectiveness of the historical air sparging/soil vapor extraction (AS/SVE) system and the current groundwater extraction and treatment system. The RPO indicated that both remedial activities offered no further benefit in meeting remediation goals. Instead, an in situ chemical oxidation (ISCO) system was recommended. Ozone was selected, and the results of a bench test indicated that the ozone demand was 8 to 12 mg ozone/mg TPH and that secondary by‐products would include hexavalent chromium and bromate. A capture zone analysis was conducted through groundwater flow modeling (MODFLOW) to ensure containment of the injected oxidant using the existing groundwater extraction system. Results of a pilot study indicated that the optimum frequency of ozone sparging is 60 minutes in order to reach a maximum radius of influence of 20 feet. TPH concentrations within the treatment zone decreased by 97 percent over two months of ozone sparging. Concentrations of hexavalent chromium and bromate increased from nondetect to 44 and 110 mg/L, respectively, during the ozone sparging but attenuated to nondetectable concentrations within three months of system shut down. ©2016 Wiley Periodicals, Inc. 相似文献
9.
A high resolution technique was applied to amniotic fluid cells by synchronization. After inoculation, the cells were incubated for 30 h in the presence of either thymidine or 5-bromodeoxyuridine (BrdU). After removal of the blocking agent and addition of a low concentration of thymidine, the cells were incubated for another 6 1/2–7 h, then harvested in prometaphase without colcemid. This technique gives a mitotic index of 3·7 per cent after thymidine synchronization and of 3·2 per cent after BrdU synchronization, and more than half of the mitoses were in the earlier phases with the chromosomes showing more than 550 bands per haploid set. GBG, GTG, and RHG prometaphases are presented. Precise high-resolution banding of chromosomes of amniotic fluid cells can increase diagnostic accuracy. 相似文献
10.
Bioventing—the injection of air into the vadose zone to increase microbial activity—is a commonly used, proven technology for remediating volatile organic compounds present in the vadose zone. Passive systems driven by wind or solar power are both more cost‐effective and sustainable than conventional systems. Such a passive system is being applied successfully to remediate a site impacted with total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylenes (BTEX) in soil. Bioventing technology was approved by the regulatory agency as an interim remedial action to remove chemicals of concern (COCs) in the vadose zone. A bioventing pilot study was conducted to evaluate the effectiveness of COC removal and collect parameters for full‐scale design and implementation. To evaluate the potential to use wind‐driven bioventing technology, two mobile weather stations were installed at the site and monitored for one month for a wind speed study. Based on the pilot‐test data and wind speed research, 12‐inch diameter funnel/vane 360‐degree wind collectors were designed as passive wind‐driven air‐injection devices and connected to existing monitoring wells. The measured air velocity ranged from 20 to 110 feet per minute during the start‐up and the first three months of operation and maintenance. Monitoring indicated a 20 percent oxygen delivery and greater than 90 percent reduction in COC concentrations, demonstrating a successful sustainable remediation with no power requirement and minimal operation and maintenance. © 2012 Wiley Periodicals, Inc. 相似文献