SUPPLEMENTAL IRRIGATION OF HORTICULTURAL CROPS IN THE HUMID REGION1

ABSTRACT: A computer model was developed in order to establish a yield predictive relationship and to estimate the water requirements for supplemental irrigation of horticultural crops in the humid region. Alternative distribution systems were developed and designed using the results from the computer model and Wood's (1980) pipe network algorithm. The capital, operational, and maintenance costs of the distribution and recommended on-farm irrigation systems were determined and used to evaluate the economic feasibility of the alternative designs. Results show that the concentration of irrigated area along the distribution system, the length of the distribution system, and cropping system all have an important effect on the economic feasibility of supplemental irrigation in Wayne County, Kentucky.     

VOTER REACTIONS TO THE 1976 WATER DEVELOPMENT AND QUALITY REFERENDA IN TEXAS1

ABSTRACT: Since 1957, Texans have had the opportunity to vote on eight referenda concerning the allocation of state funds for water resources development and the maintenance of water quality. In 1976, a water development amendment and a water quality amendment were presented simultaneously to the voters of Texas, affording a unique opportunity for electoral-geographic comparison of county-level returns on the two issues. In this paper, cartographic and statistical analyses of the county-level voting outcomes for each referendum are presented. In both cases, the referenda were supported by voters in water-deficient West Texas, especially those counties dependent on irrigated crop production. In contrast, urban voters and East Texans tended to oppose both amendments. However, support for the water quality amendment in the urbanized areas of Dallas-Fort Worth, Austin, and San Antonio enabled this amendment to pass statewide while its counterpart failed. The results highlight the importance of local differences in perceived water policy needs, and in doing so they illustrate that geographical anlaysis of returns from initiatives and referenda is a useful tool for understanding the locational conflicts underlying water resources and other policy efforts.     

Abatement of ammonia and hydrogen sulfide emissions from a swine lagoon using a polymer biocover

The purpose of this research was to determine the efficiency of a polymer biocover for the abatement of H2S and NH3 emissions from an east-central Missouri swine lagoon with a total surface area of 7800 m2. The flux rate of NH3, H2S, and CH4 was monitored continuously from two adjacent, circular (d = 66 m) control and treatment plots using a nonintrusive, micrometeorological method during three independent sampling periods that ranged between 52 and 149 hr. Abatement rates were observed to undergo a temporal acclimation event in which NH3 abatement efficiency improved from 17 to 54% (p = < 0.0001 to 0.0005) and H2S abatement efficiency improved from 23 to 58% (p < 0.0001) over a 3-month period. The increase in abatement efficiency for NH3 and H2S over the sampling period was correlated with the development of a stable anaerobic floc layer on the bottom surface of the biocover that reduced mass transfer of NH3 and H2S across the surface. Analysis of methanogenesis activity showed that the biocover enhanced the rate of anaerobic digestion by 25% when compared with the control. The biocover-enhanced anaerobic digestion process was shown to represent an effective mechanism to counteract the accumulation of methanogenic substrates in the biocovered lagoon.     

The reliability of 2,3,7,8-tetrachlorodibenzo-p-dioxin and toxicity equivalence measurements in Missouri residents

This study evaluates the reliability of serum measurements of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and toxicity equivalence (TEQ) in individuals with no prior exposure to TCDD or dioxin-like compounds above background levels. Reliability was measured over three time-periods in the same individuals. TCDD and TEQ were measured in 127 and 128 participants. The values declined during the testing periods. Reliability coefficients for TCDD was 0.69 and for TEQ 0.91 but increased to 0.79 and 0.92, respectively, after removal of three outlying cases. Study results show good reliability over 22 months suggesting a consistency in the uptake and excretion of TCDD and other dioxin-like compounds.     

Interpreting organic solute transport data from a field experiment using physical nonequilibrium models

In a field experiment, two inorganic tracers and five organic solutes were injected into an unconfined sand aquifer. Breakthrough response curves were obtained at several points downgradient of the injection zone. These response curves are analyzed using a model which assumes equilibrium sorption and two models which postulate physical nonequilibrium. The physical nonequilibrium models hypothesize the existence of zones of immobile water, which act as diffusion sources and sinks for the solutes. The physical nonequilibrium models better simulate the sharp breakthrough and extended tailing exhibited by the experimental responses than does the model assuming equilibrium sorption. The reasonableness of parameters obtained from curve-fitting the data is assessed. The two physical nonequilibrium models are compared.     

Linkages between best practice in business and good environmental performance by companies

Is the adoption of currently accepted best practice in business associated with improved environmental performance by companies? What methods can be used to assess and compare the environmental practices and performance of different companies? In this pilot study, the business and environmental practices and performances of five companies in the metal working sector were examined and scored. The business practices and performances were assessed using the best practice model adopted in the Australian Manufacturers Council study (AMC, November 1994, Melbourne, 112pp.). The environmental practices and performance of the companies were assessed based on a five stage framework of business response to environmental issues presented here. A strong correlation was observed between environmental performance and business practices (correlation coefficient, r = 0.85, p < 0.05). The company closest to best practice had a strong focus on quality, efficiency and elimination of waste, well-developed strategy, good teamwork and a high level of commitment and also had the highest score for environmental performance. The company with poorest score for its business practices had the poorest environmental performance, with the remaining companies lying between on both scores. There was no significant correlation between business performance outcomes and environmental performance.     

户外测试检验加速测试

探讨了加速老化测试存在的问题,阐述了户外暴露测试的重要性,指出应该利用户外暴露测试来检验加速老化。使用正确的测试程序,户外暴露测试．-j-~在较短的时间内获得较好的测试结果。采用正确的测试设计、恰当的评估方法、可靠的统计分析及应用参照样品等,可使测试者确定加速程度及加速测试与户外暴露测试的相关系数,以确保加速测试结果的正确性。