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91.
Water Quality during Development and Apportionment of Pollution from Rivers in Tapeng Lagoon, Taiwan
This work investigated water samples collected from Tapeng Lagoon, Taiwan. Factor analysis was conducted to explain the characteristics and the variation in the quality of water during the disassembly of oyster frames and fishery boxes. The result shows that the most important latent factors in Tapeng Lagoon are the ocean factor, primary productivity factor, and the fishery pollution factor. Canonical discriminant analysis is applied to identify the source of pollution in neighboring rivers outside Tapeng Lagoon. The two constructed discriminant functions (CDFs) showed markedly contribution to all discriminant variables, and that total nitrogen, algae, dissolved oxygen and total phosphate, combined in the nutrient effect factor. The recognition capacities in these two CDFs were 95.6%, 4.4%, respectively. The water quality in the Kaoping river most strongly determined that in the Tapeng Lagoon the best is. And disassembling the oyster frames and fishery boxes improves the water quality markedly. However, environmental topographic conditions indicate that strengthening stream pollution prevention and to constructing another entrance to the ocean are the best approaches for improving the quality of water in Tapeng Lagoon, especially by reducing eutrophication. These approaches and results yield useful information concerning habitat recovery and water resource management. 相似文献
92.
To investigate the effect of temperature on effective diffusion coefficients and retardation factors for Zn and Cd, combined
diffusion and sequential extraction analyses were conducted at 15 ˚C and 55 ˚C. The effective diffusion coefficients of the metals increased up to ten times according to the increased temperature. On
the other hand, the effect of temperature on the retardation factor depended on the retention mechanisms of the metals. The
distribution coefficient for Zn, which was mainly partitioned in the carbonate phase, increased up to two times with the increase
in temperature. On the other hand, the distribution coefficient for Cd, which was mainly partitioned in the exchangeable phase,
was hardly affected by the temperature change. Results of combined diffusion and sequential extraction analysis showed that
the effect of temperature on the heavy metals’ (Zn and Cd) migration through the compacted natural clay was influenced by
the combined effects of the diffusion coefficient and the retardation factor. Additionally, we could also observe the change
in retention mechanism for the metals with the change in pore water concentration. 相似文献
93.
This study uses knowledge discovery concepts to analyze large amounts of data step by step for the purpose of assisting in the formulation of environmental policy. We performed data cleansing and extracting from existing nation-wide databases, and used regression and classification techniques to analyze the data. The current water hardness in Kaohsiung, Taiwan contributes to the prevention of cardiovascular disease (CVD) but exacerbates the development of renal stones (RS). However, to focus on water hardness alone to control RS would not be cost effective at all, because the existing database parameters do not adequately allow for a clear understanding of RS. Analysis of huge amounts of data can most often turn up the most reliable and convincing results and the use of existing databases can be cost-effective. 相似文献
94.
Tillage and field scale controls on greenhouse gas emissions 总被引:3,自引:0,他引:3
There is a lack of understanding of how associations among soil properties and management-induced changes control the variability of greenhouse gas (GHG) emissions from soil. We performed a laboratory investigation to quantify relationships between GHG emissions and soil indicators in an irrigated agricultural field under standard tillage (ST) and a field recently converted (2 yr) to no-tillage (NT). Soil cores (15-cm depth) were incubated at 25 degrees C at field moisture content and 75% water holding capacity. Principal component analysis (PCA) identified that most of the variation of the measured soil properties was related to differences in soil C and N and soil water conditions under ST, but soil texture and bulk density under NT. This trend became more apparent after irrigation. However, principal component regression (PCR) suggested that soil physical properties or total C and N were less important in controlling GHG emissions across tillage systems. The CO2 flux was more strongly determined by microbial biomass under ST and inorganic N content under NT than soil physical properties. Similarly, N2O and CH4 fluxes were predominantly controlled by NO3- content and labile C and N availability in both ST and NT soils at field moisture content, and NH4+ content after irrigation. Our study indicates that the field-scale variability of GHG emissions is controlled primarily by biochemical parameters rather than physical parameters. Differences in the availability and type of C and N sources for microbial activity as affected by tillage and irrigation develop different levels and combinations of field-scale controls on GHG emissions. 相似文献
95.
96.
With the increase in employment of Internet surveys, there is a need to address how this survey mode affects inferences. Internet and interview modes are compared in estimating the preservation value of Dokdo, South Korea. Estimates of willingness to pay in the Internet survey are smaller than those in the interview survey. This may be attributable to the interview respondents being conscious of the presence of the interviewers, given the social importance of Dokdo to Koreans. Internet surveys may be effective in reducing overestimation of the willingness to pay in situations where potential social desirability is present. 相似文献
97.
Income and distance-decay effects on willingness to pay estimated by the contingent valuation method
Jongyearn Lee 《Journal of Environmental Planning and Management》2016,59(11):1957-1981
This study suggests a methodology for enhancing accuracy in evaluating amenity by the contingent valuation method when household's willingness to pay (WTP) is dependent to its income and the distance between a respondent's residence and the location of a target facility. Using a linear city model, this study demonstrates the influences of income and distance-decay effects on WTP. Simulations are performed to check the validity of the model, as well as to predict consequences when income and distance-decay effects are not properly treated. Finally, the suggested methodology is applied to two real cases. The estimation results from a structural model show that the calculated total benefit varies largely when income and distance-decay effects exist and are ignored. Also, an ad hoc model generates significantly different estimates from the utility difference model this study adopted. The difference in estimates suggests that the total benefit has to be estimated by a structural model. 相似文献
98.
In this paper, an isolated ac module with pseudo dc-link and galvanic isolation is proposed for photovoltaic energy conversion. The studied grid-tie ac module can individually extract the maximum solar power from each photovoltaic panel and transfer to ac utility system. It consists of an interleaved active-clamping single-ended primary-inductive circuit (SEPIC) with a secondary voltage doubler, a full-bridge polarity selector operating under line frequency to achieve high efficiency. For the studied topology, key features such as reduced input current ripple, zero-voltage switching (ZVS) of primary switches, low reverse-recovery current of the output diodes, and lower switch voltage stress are obtained. Also, to reduce input current ripple, an interleaved control strategy is adopted. A simple control strategy is proposed to generate a rectified sinusoidal waveform voltage at the pseudo dc-link capacitors and achieve the high maximum power point tracking (MPPT) accuracy. The operation principles and design considerations of the studied ac module are analyzed and discussed. A prototype with 25–60 V dc input, 110 V/60 Hz ac output and 150 W power rating has been constructed for verifying the feasibility of the proposed ac module. 相似文献
99.
An organic Rankine cycle (ORC) is generally used for converting low-grade heat into electricity. In this study, an extensive literature survey was conducted to identify current research gaps on experimental ORC systems. Specifically, there is limited experimental data and limited details on thermal and expander efficiencies of ORC systems. In order to address these gaps, the objective of this study included developing a turbine ORC with a power output exceeding 50 kW and thermal efficiency exceeding 8% for a heat source temperature < 120°C. The experimental results indicated that the system achieved a net power output of 242.5 kW and a thermal efficiency of 8.3% (the highest value for a turbine ORC system for the heat source temperature below 120°C). Thus, the study addressed the gaps identified in the research area of ORCs. 相似文献
100.