On-site Phase Research Articles

Water-quality monitoring technique for dioxins during dredging using on-site solid phase extraction with graphitic carbon and analysis with DR-CALUX

In Japan, water-quality monitoring with the environmental dioxin standard of 1 pg-TEQ/L at basic monitoring points set in a border between operation-area water and normal water is necessary for removal operations for bottom sediments containing dioxins. This paper presents a technique for combining on-site graphitic carbon (GrC) solid-phase extraction and bioassay method for the simplification and facilitation of water-quality monitoring. Using this method, we conducted experiments at an actual sediment removal site. Comparative analyses using high-resolution GC/MS (HRGC–HRMS) between the dioxin concentrations detected using a GrC solid-phase extraction kit and the official analytical method yielded similar concentrations and distributions of isomers for detected PCDD/Fs and DL-PCBs. The GrC solid-phase extraction method is inferred to have capacity equal to official analytical method extraction. Toxicity equivalent concentrations estimated using DR-CALUX correlate with equivalent concentrations with HRGC/HRMS. No false positive or false negative result was obtained for the standard value 1 pg-TEQ/L.

The Dynamic, Emergent, and Multi-Phasic Nature of On-Site Wilderness Experiences

Feelings and cognitions of leisure may not only be dynamic during the course of the total outdoor recreation engagement, they may be dynamic, emergent, and multi-phasic during the on-site phase. Experience Sampling Method data were collected from a sample of wilderness visitors multiple times during a visit to the Okefenokee National Wildlife Refuge. Four modes of environmental experience (focus on self, others, task, and environment) and four aspects of wilderness experience (a combined oneness/primitiveness/humility variable, timelessness, solitude, and care) were measured. Univariate and multivariate repeated measures analyses demonstrated significant change from the entry, through immersion, to the exit phases of the wilderness experience. This experiential change included greater focus on the environment and on self/in-trospection at the exit compared to the entry phase, and less focus on others/social acceptance during the immersion phase. Scores on humility/primitiveness/oneness were higher at both the immersion and exit phases than during entry, and care for the wilderness was higher during the exit phase than during entry. Implications of findings for understanding the complex nature of leisure experiences are provided.

On-site Optimal Experiences and Their Relationship to Off-site Benefits

This paper examines: (a) the quantity of optimal experiences got during the on-site phase of outdoor recreation; (b) the quantity of benefits gotten off-site, during the recollection phase of outdoor recreation; and (c) the relationship between (a) and (b). Optimal experiences—a psychological state considered to be special, meaningful, and/or out-of-the-ordinary—are characterized by intense focus on a stimulus, an altered sense of time, and loss of consciousness of the self. A three item scale, part of an on-site questionnaire, was developed to measure the quantity of optimal experiences outdoor recreationists reported getting. The quantity of benefits recollected off-site was measured using a follow-up, mail-out questionnaire (n = 169). Regression analyses found significant relationships between the quantity of optimal experiences and the quantity of three benefit categories. With the higher meaning and social interaction benefit categories, the relationships were quadratic; indicating that high quantities of optimal experience produced higher quantities of these benefit categories vs. very low, low, moderate, and very high quantities of optimal experience. This type of relationship suggests that very high quantities of optimal experiences may result in disbenefits—possibly due to the addictive nature of very high quantities of optimal experiences. With the greater knowledge benefit category, the relationship was cubic; indicating that very low and high quantities of optimal experiences may produce higher quantities of this benefit category vs. low, moderate, and very high quantities of optimal experiences. Management implications and research recommendations are discussed.

On-site solid phase extraction and coupled-column high-performance liquid chromatographic determination of six polycyclic aromatic hydrocarbons in water

A high-performance liquid chromatographic method for the determination of fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, benzo(g,h,i)perylene and indeno(1,2,3-cd)pyrene in water is presented. The analytical procedure consists of on-site solid-phase extraction of the analytes on a selective sample column using a new device, transport and integration of the loaded sample column into a HPLC-system and coupled-column HPLC-analysis. The method allows reliable quantification of the PAHs at the low ng/l-level in particle-free as well as in particle-containing surface water.

Approximate Markov Modeling of High-Reliability Telecommunications Systems

The reliability model of a system with redundancy but only a single repairman is Markov only if the component failure rates and the repair rate are constants. This paper introduces a method with which a reliability analyst can formulate an approximate (time-homogeneous) Markov model for a system with 1-out-of-2 redundancy when repair is nonexponential (repair rate is time-dependent). This approximate model yields accurate steady-state predictions of system reliability when time-to-repair is orders of magnitude smaller than timeto-component-failure, as is typical in high-reliability telecommunications systems. Transition rates and error bounds for the approximate model are given based on the first three moments of the repair time distribution. An application of the method is shown for the system in which repair time is composed of a "next day" parts delivery phase followed by an on-site repair phase.