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Observations on the methane oxidation capacity of landfill soils 总被引:1,自引:0,他引:1
Chanton J Abichou T Langford C Spokas K Hater G Green R Goldsmith D Barlaz MA 《Waste management (New York, N.Y.)》2011,31(5):914-925
The objective of this study was to determine the role of CH4 loading to a landfill cover in the control of CH4 oxidation rate (g CH4 m−2 d−1) and CH4 oxidation efficiency (% CH4 oxidation) in a field setting. Specifically, we wanted to assess how much CH4 a cover soil could handle. To achieve this objective we conducted synoptic measurements of landfill CH4 emission and CH4 oxidation in a single season at two Southeastern USA landfills. We hypothesized that percent oxidation would be greatest at sites of low CH4 emission and would decrease as CH4 emission rates increased. The trends in the experimental results were then compared to the predictions of two differing numerical models designed to simulate gas transport in landfill covers, one by modeling transport by diffusion only and the second allowing both advection and diffusion. In both field measurements and in modeling, we found that percent oxidation is a decreasing exponential function of the total CH4 flux rate (CH4 loading) into the cover. When CH4 is supplied, a cover’s rate of CH4 uptake (g CH4 m−2 d−2) is linear to a point, after which the system becomes saturated. Both field data and modeling results indicate that percent oxidation should not be considered as a constant value. Percent oxidation is a changing quantity and is a function of cover type, climatic conditions and CH4 loading to the bottom of the cover. The data indicate that an effective way to increase the % oxidation of a landfill cover is to limit the amount of CH4 delivered to it. 相似文献
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Ten separate experiments monitoring the simultaneous behaviors of 26 skipjack (Katsuwonus pelamis), 26 bigeye (Thunnus obesus), and 33 yellowfin (T. albacares) tunas within large multi-species aggregations associated with drifting fish aggregating devices (FADs) were investigated using ultrasonic telemetry in the equatorial eastern Pacific Ocean. Experiments were conducted during a research cruise aboard a chartered purse seine vessel. Purse seine sets were made on the tuna aggregations associated with FADs at the termination of six of the ten experiments. Seventeen of the 44 tagged tunas were not recaptured indicating the transient nature of the associative behavior of tunas with FADs. Although there was considerable overlap in the depths of the three species, by day and night, there were some species-specific differences and diel differences within species. While we documented spatial and temporal differences in the schooling behavior of the three tuna species, the differences do not appear sufficient such that modifications in purse seine fishing practices could effectively avoid the capture of small bigeye and yellowfin tunas, while optimizing the capture of skipjack tuna in purse seine sets on FADs. 相似文献
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