WATER REUSE FROM SEWAGE EFFLUENT BY IRRIGATION: A PERSPECTIVE FOR HAWAII1

ABSTRACT: Surrounded by an ocean, the Hawaiian Islands are limited in their natural fresh water resources. The major readily developable potable sources are the high quality ground water sources which serve both domestic uses and sugarcane irrigation although irrigation water does not require as high a quality as drinking water. The increasing overall fresh water requirements for the island of Oahu will outstrip the potential yield of fresh ground water sources, as developed by present technology, by the year 2000 according to Honolulu Board of Water Supply projections. There are water shortage regions on other islands. Water reuse from sewage effluent for irrigation will augment natural water resources, furnish supplemental or alternative fertilizer, and reduce ocean water pollution and the costs of engineering systems. In cooperative field testing from 1971 to 1975, it was demonstrated that effluent can be applied as supplemental water for furrow irrigation of sugarcane without detriment to ground water quality and sugar yield. Studies are in progress to test different dilutions of effluent and its use with chemical ripeners to improve crop yield. Sugarcane plantations on Oahu, Maui, and Kauai are in various stages of water reuse by effluent irrigation. Reuse is presently practiced for irrigation of golf courses and is being planned for forage crops in Hawaii.     

Individual attributes and leadership style: predicting the use of punishment and its effects

This study examined attributes of leaders that influenced their use of contingent and noncontingent punishment and the results of using punishment on leader effectiveness. Results indicated that leaders with higher levels of physical fitness and moral reasoning were more likely to use contingent punishment, while those with lower self-esteem were more likely to use noncontingent punishment. Noncontingent punishment negatively impacted leader effectiveness, while contingent punishment positively impacted leader effectiveness. © 1998 John Wiley & Sons, Ltd.     

Air ventilation impacts of the “wall effect” resulting from the alignment of high-rise buildings

The objective of this study is to investigate the air ventilation impacts of the so called “wall effect” caused by the alignment of high-rise buildings in complex building clusters. The research method employs the numerical algorithm of computational fluid dynamics (CFD – FLUENT) to simulate the steady-state wind field in a typical Hong Kong urban setting and investigate pollutant dispersion inside the street canyon utilizing a pollutant transport model. The model settings of validation study were accomplished by comparing the simulation wind field around a single building block to wind tunnel data. The results revealed that our model simulation is fairly close to the wind tunnel measurements. In this paper, a typical dense building distribution in Hong Kong with 2 incident wind directions (0° and 22.5°) is studied. Two performance indicators are used to quantify the air ventilation impacts, namely the velocity ratio (VR) and the retention time (T_r) of pollutants at the street level. The results indicated that the velocity ratio at 2 m above ground was reduced 40% and retention time of pollutants increased 80% inside the street canyon when high-rise buildings with 4 times height of the street canyon were aligned as a “wall” upstream. While this reduction of air ventilation was anticipated, the magnitude is significant and this result clearly has important implications for building and urban planning.     

A New All Season Passive Sampling System for Monitoring Ozone in Air

A new all season passive sampling system for monitoring O₃ in the atmosphere has been developed in the laboratory and validated in the field. The unique features for this system include a newly designed passive sampler and a rain shelter, which allow the passive sampler to be installed in the field facing downwards. An equation associated with meteorological parameters is used to calculate the passive sampling rates. This system has been extensively tested in the lab (temperature from –18 to 20°C, relative humidity from 13 to 81%, and wind speed from 0.5 to 150 cm/s) and validated in the field in climates of all seasons. The accuracy of the ozone concentrations in the atmosphere obtained with the use of the new passive sampling system was higher than 85% compared to those obtained with continuous ozone analyzers. The new ozone passive sampling system can be used to measure ambient O₃ concentrations ranging from 3 ppb to 1000 ppb based on one-day exposure and 0.1 ppb to 140 ppb for a monthly exposure period. It is also reasonable to conclude that the new passive sampling system can be used for eight-hour exposure study because of the low field blanks and high sampling rates.     

Radon as a naturally occurring tracer for the assessment of residual NAPL contamination of aquifers

The noble gas radon has a strong affinity to non-aqueous phase-liquids (NAPLs). That property makes it applicable as naturally occurring partitioning tracer for assessing residual NAPL contamination of aquifers. In a NAPL contaminated aquifer, radon dissolved in the groundwater partitions preferably into the NAPL. The magnitude of the resulting radon deficit in the groundwater depends on the NAPL-specific radon partition coefficient and on the NAPL saturation of the pore space. Hence, if the partition coefficient is known, the NAPL saturation is attainable by determination of the radon deficit. After a concise discussion of theoretical aspects regarding radon partitioning into NAPL, related experimental data and results of a field investigation are presented. Aim of the laboratory experiments was the determination of radon partition coefficients of multi-component NAPLs of environmental concern. The on-site activities were carried out in order to confirm the applicability of the "radon method" under field conditions.     

Acute and chronic toxicities of tributyltin to various life stages of the marine polychaete Hydroides elegans

Experiments were performed to determine the acute and chronic toxicities of tributyltin (TBT) (nominal concentrations) to polychaete Hydroides elegans. Firstly, static tests were performed to examine the lethal effect of TBT on five life stages of H. elegans. The 48-h LC(50) (95% CI) for the eggs, 2-cells, trochophores, juveniles and adults was 0.18 (0.15-0.20), 0.97 (0.77-1.23), 2.36 (2.11-2.65), 2.86 (2.63-3.12) and 4.36 (4.04-4.71) microg TBT l(-1), respectively. Secondly, a 17-d static renewal chronic test was conducted to study sensitivity of the early development (egg to juvenile) to TBT. The survivorship, percent settlement and time to reach settlement were significantly reduced at 0.01 microg TBT l(-1). Effects of TBT on the juvenile growth and maturation were also studied through a 44-d chronic test. Lower survivorship and reduced tube growth were observed only at >or= 1 microg TBT l(-1), however, only H. elegans exposed to or= 0.1 microg TBT l(-1). Our results indicate that the early development of H. elegans is highly sensitive to TBT and this polychaete can be routinely employed as a test organism for both acute and chronic ecotoxicity bioassays in tropical and subtropical regions such as southern China.     

Removal of phosphate from water by a highly selective La(III)-chelex resin

A new polymer ligand exchanger (PLE) has been developed for the removal of phosphate in wastewater. This PLE, consisting of lanthanum(III) bound to chelex-100 resin, was prepared by passing LaCl3 solution through a column of chelex-100. Uptake of phosphate from water by this La-chelex resin was investigated in the column mode. The La-chelex resin was able to remove phosphate efficiently from water, and the uptake of phosphate was not affected by the presence of large amounts of anions (0.1M) such as chloride and sulfate. The La-chelex resin was also able to efficiently remove phosphate from seawater to <0.1mg-Pl(-1), and regenerated for reuse by removing the sorbed phosphate by eluting with 6M HCl.     

Obesity Kuznets curve hypothesis and global warming: a robust estimation under cross-section dependence

Environmental Science and Pollution Research - Obesity is a worldwide concern as it leads to adverse effects on human health. This study uses a panel of 165 countries and annual data from 2000 to...     

微波消解-电感耦合等离子体质谱(ICP-MS)法同时测定塑料中的铅、镉、汞、铬、砷

建立了微波消解-电感耦合等离子体质谱同时测定各种塑料中的铅、镉、汞、铬、砷等元素的方法.对仪器的参数设置、进样系统的选择、测试稳定性等方面进行了系统研究,并对塑料标准样品中上述元素分析的前处理条件如消解体系、酸用量、消解温度及时间等进行了优化.方法检出限为0.7-6.5 ng·g-1,加标回收率为89.8%-103.5%,相对标准偏差为0.8%-11.3%.