Search

Depleted appliance trap seals were shown to be a causal factor in the spread of the SARS virus at the Amoy Gardens housing complex in Hong Kong in 2003. This serious health risk has emphasised the requirement for an effective maintenance regime to ensure trap seals do not again facilitate the spread of infection and disease. This paper introduces a remote and non-invasive technique to identify depleted trap seals through analysis of the system response to an applied sinusoidal pressure wave. The pressure signal will be analysed in both the time domain and the frequency domain to determine system status. Results obtained from laboratory experiments will be used to confirm the practicality of this technique while a Method of Characteristic based numerical model will validate the methodology. Practical application: The transients generated within the building drainage system as a result of normal system operation continue to pose a threat to the integrity of the appliance trap seal. The technique outlined in this paper will help to quickly identify defective trap seals to ensure that cross-contamination is minimised. However, it is important that this transient-based technique does not itself introduce an additional risk to trap integrity. A sinusoidal pressure wave offers a completely non-invasive testing option that will not only be of great advantage to facility managers but also to the building users due to the reduced risk of cross-contamination. [ABSTRACT FROM AUTHOR]

Quantifying the relative influences of anthropogenic activities and climate change on soil erosion and deposition during the Holocene, when both forces have been interacting is a complex problem. Analysis of long-term patterns in soil erosion and lake deposition in a basin can provide the basis for untangling the complexities of climate and anthropogenic forcings. In this paper, sedimentary sequences from Xingyun Lake are compared with simulated soil erosion rates in the basin to explore the relationship between river basin soil erosion and lake deposition during the Holocene in Yunnan, China. Modern soil erosion rates are calculated using RUSLE, while Holocene soil erosion rates are estimated using modern rates with reconstructed precipitation and vegetation cover sequences. Through this investigation, we found the following results. First, Holocene vegetation in the lake basin was mainly affected by climate change, and the vegetation experienced the same pattern of changes as the climate. Soil erosion and lake deposition rates, along with changes to vegetation cover, were synchronous with precipitation trends during the Holocene. Second, soil erosion and lake deposition have been exacerbated by human activities, such as deforestation and land reclamation in the Xingyun Lake basin. Finally, this study provides new insights into the effects by anthropogenic impacts and climate forcing on the processes of soil erosion and lake deposition on the millennium scale. [ABSTRACT FROM AUTHOR]

Using a new framework combining vulnerability and exclusion as two central dimensions of poverty, this article revisits some of the long-standing beliefs about poverty in small-scale fisheries. We argue that the issue of poverty in fish-dependent communities cannot be reduced to a simple correlation between income poverty and fishery dependence. A more thorough analysis is required that must account for the diversity of fishing-related livelihoods and the complexity of causes of poverty, both inside and outside the sector. The article highlights how poverty in fishing communities often relates to a wide range of socio-institutional factors other than income, including landownership, debt, access to health, education and financial capital, and marginalisation from political decision making. The empirical examples used in this article refer to inland capture fisheries from the Volta and Mekong basins but, arguably, the analysis applies to other fisheries (inland and coastal) in developing countries. [ABSTRACT FROM PUBLISHER]

Massive carbonate banks representing ancient lacustrine deposits are exposed in the catchment of the lake Tangra Yumco (southern-central Tibetan Plateau) and nearby lake Xuru Co. Nine sediment samples were taken below and above these lacustrine deposits to determine periods of changing lake level using optically stimulated luminescence (OSL) applying a multiple-aliquot regeneration (MAR) protocol. According to facies and stratigraphy, samples below the carbonate banks indicate a rising and samples from above a falling lake level. The results indicate that the rising lake level of Tangra Yumco passed the sampling location at 10.5 and 2.1 ka while a falling lake level passed the sampling location at 0.9 ka. The rising lake level of Xuru Co passed the sampling location at 7.9 and 1.7 ka and a falling lake level at 0.5 ka showing a similar trend as at Tangra Yumco. Combining these results with recalculated cosmogenic nuclide ages and previously published feldspar luminescence data allows the establishment of a Holocene lake level reconstruction for Tangra Yumco, which is unique for the southern-central Tibetan Plateau. The lake level of Tangra Yumco crested a lake level highstand of 181–183 m above the recent lake level prior to 8.5 ka and has generally fallen after 8.5 ka, with a minor lake level rise at 2.1 ka. Lake level variations at Tangra Yumco occur simultaneously with other lakes on the Tibetan Plateau indicating that variations were controlled by monsoonal dynamics with a moist early Holocene and a successive reduction of available moisture thereafter. The average rate of the lake level rise between 10.5 and 8.5 ka is at least 0.05 m a−1 (compared with a modern value of 0.38 m a−1), providing valuable insights in the monsoonal impact on lake level change on the southern-central Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Lacustrine ecosystem history since the industrial revolution provides important evidence of natural versus anthropogenic effects on the environment. With high-resolution sedimentary core samples and organic–inorganic geochemical methods, we reconstruct the past ~150-year ecosystem evolution of Lake Wuliangsu in the upper reaches of the Yellow River, and probe factors controlling the ecological dynamics. In this study, ecological changes in Lake Wuliangsu over the past ~150 years were identified. After the lake formed in the 1850s, biological productivity of the lake was still under-developed until the 1950s. During the period of 1950s–1970s, submerged macrophytes became the dominant organisms in the lake because of lake area expansion and slight increases of nutrient input from agricultural development in the catchment. The domination of submerged macrophytes ceased after the 1970s, which was possibly induced by the shrinkage of the lake area. After the 1990s, the main contributor of sedimentary n-alkanes most likely shifted to reeds because of eutrophication caused by anthropogenic activities. The results clearly demonstrate that the ecosystem in Lake Wuliangsu before the 1950s strongly depended on the natural discharge, whereas at later stages, it was significantly influenced by human activities. During the period of 1950s–1990s, the human-monitored lake area seems to be the main factor in the lake ecosystem evolution. However, when the nutrient supply went beyond the tipping point after the 1990s, eutrophication took over and played a key role in the lake ecosystem evolution. [ABSTRACT FROM AUTHOR]

Drainage demand estimation for an effective and healthy drainage stack design is examined in this study. Empirical expressions that incorporate building occupant load, simultaneous usage patterns and discharge flow attenuation along a horizontal pipe into the probable drainage load determination for a stack serving a number of domestic washrooms as installed in typical high-rise buildings in Hong Kong are proposed. Patterns of probable drainage demand and probable discharge flow in the stack are determined via Bayesian analysis and Monte Carlo simulations, respectively. The study outcome enables more effective sizing of a drainage stack for some residential buildings in a dense urban environment. Practical application: Providing a mathematical model for drainage load calculations, this study is a useful tool to aid drainage stack sizing for some high-rise residential buildings. [ABSTRACT FROM AUTHOR]