Statistical evaluation of an agricultural land suitability model

The land evaluation and site assessment (LESA) method has been used extensively in the United States to assess agricultural land suitability for different localities. Despite widespread use, LESA models rarely have been evaluated in a systematic, comprehensive manner. This article discusses development of a LESA system for Hawaii, the first statewide application of the LESA methodology. The empirical model was implemented with a computerized geographic information system (GIS). The system's efficiency, ability to discriminate among land parcels, and robustness to subjective model parameter values are evaluated with statistical analyses and map overlays of GIS data. Results show great potential to simplify the original model specification, primarily through deletion of marginal site assessment factors. System output was generally insensitive to the numeric values selected for model parameters, with exception of the ratio used to combine the land evaluation (LE) and site assessment (SA) component scores. Relative supplies of the differing land attributes measured by the two components must be considered in determining an appropriate LE:SA ratio for a given area.     

Compliance with regulations by "swim-with-dolphins" operations in Port Phillip Bay,Victoria, Australia

Managing the activities of commercial wildlife viewing tends to involve either restricting the number of industry participants and/or regulating the activities or industry participants. We report on operator compliance with regulations regarding humans swimming with free-ranging bottlenose dolphins ( Tursiops sp.) in Port Phillip Bay, Victoria, Australia. A total of 128 commercial dolphin-swim trips was studied between September 1998 and April 2000. Four permit conditions were investigated: approach type, swim time, time in proximity of dolphins, and presence of "fetal fold" calves. Results demonstrate noncompliance by operators to all of the four permit conditions studied. Compliance with temporal conditions was poorer than with other conditions. When conducting studies on the extent to which tourism affects cetaceans, investigators should consider whether tourist operations comply with existing regulations or guidelines.     

The effective and environmental half-life of 137Cs at Coral Islands at the former US nuclear test site

The United States (US) conducted nuclear weapons testing from 1946 to 1958 at Bikini and Enewetak Atolls in the northern Marshall Islands. Based on previous detailed dose assessments for Bikini, Enewetak, Rongelap, and Utirik Atolls over a period of 28 years, cesium-137 (137Cs) at Bikini Atoll contributes about 85-89% of the total estimated dose through the terrestrial food chain as a result of uptake of 137Cs by food crops. The estimated integral 30, 50, and 70-year doses were based on the radiological decay of 137Cs (30-year half-life) and other radionuclides. However, there is a continuing inventory of 137Cs and 90Sr in the fresh water portion of the groundwater at all contaminated atolls even though the turnover rate of the fresh groundwater is about 5 years. This is evidence that a portion of the soluble fraction of 137Cs and 90Sr inventory in the soil is lost by transport to groundwater when rainfall is heavy enough to cause recharge of the lens, resulting in loss of 137Cs from the soil column and root zone of the plants. This loss is in addition to that caused by radioactive decay. The effective rate of loss was determined by two methods: (1) indirectly, from time-dependent studies of the 137Cs concentration in leaves of Pisonia grandis, Guettarda specosia, Tournefortia argentea (also called Messerschmidia), Scaevola taccada, and fruit from Pandanus and coconut trees (Cocos nucifera L.), and (2) more directly, by evaluating the 137Cs/90Sr ratios at Bikini Atoll. The mean (and its lower and upper 95% confidence limits) for effective half-life and for environmental-loss half-life (ELH) based on all the trees studied on Rongelap, Bikini, and Enewetak Atolls are 8.5 years (8.0 years, 9.8 years), and 12 years (11 years, 15 years), respectively. The ELH based on the 137Cs/90Sr ratios in soil in 1987 relative to the 137Cs/90Sr ratios at the time of deposition in 1954 is less than 17 years. The magnitude of the decrease below 17 years depends on the ELH for 90Sr that is currently unknown, but some loss of 90Sr does occur along with 137Cs. If the 15-year upper 95% confidence limit on ELH (corresponding to an effective half-life of 9.8 years) is incorporated into dose calculations projected over periods of 30, 50, or 70 years, then corresponding integral doses are 58, 46 and 41%, respectively, of those previously calculated based solely on radiological decay of 137Cs.     

A framework for assessing the sustainability of brownfield developments

In England, the development of urban brownfield sites is a significant planning policy aimed at supporting urban regeneration and protecting the countryside. Brownfield sites are required, in policy, to be developed in a sustainable way. However, determining what this means in practice is unclear. This paper presents a framework for assessing the sustainability of brownfield developments, devised to clarify the stakeholders in land reuse and establish how sustainability can be achieved on reused sites. The framework has been used in research investigating the sustainability of five brownfield developments in England. The performance of the framework in this research is assessed and its potential practical use outlined.     

Oxidation of chlorophenols in soil at natural pH by catalyzed hydrogen peroxide: the effect of soil organic matter.

This investigation reports on the effects of soil organic matter (SOM) during the oxidation of chlorophenols with Fe2+-catalyzed H2O2 (Fenton oxidation) system. The soil pH was 7.1 and was not altered. Sorption experiments of soil pre-treated under various oxidation conditions were performed. Concentrations of organic matter in the liquid phase and soil before and after oxidation were analyzed. The results were correlated to the observation in batch Fenton oxidation tests. They showed that the oxidation of chlorophenols at natural soil pH depended on the dose of H2O2 and Fe2+. The soil organic content did not vary significantly after various Fenton treatments, while the sorption of chlorophenols was 10-25% less by the oxidation. The concentration of chlorophenols in the liquid phase exhibited a "decrease and rebound" phenomenon in the batch Fenton oxidation tests. It appeared that the oxidation of SOM resulted in the release of sorbed chlorophenols which were then oxidized by the excess H2O2. An "oxidation-desorption-oxidation" scheme was proposed to describe one of the interaction mechanisms among the oxidant, SOM, and chlorophenols during oxidation.     

Predicting the frequency of accidents in port areas by developing event trees from historical analysis

The historical analysis of 828 accidents in port areas, which have been selected from a database, has been used to identify the sequences of the accidents. Processing these data has allowed the event trees and the probability of the various accident scenarios to be determined. By using these event trees and figures detailing the frequency of the events that initiated the accidents, as taken from various authors, the frequency of the accidents has been determined.