SEQUENTIAL WATER REUSE EFFECT ON STREAM SALINITY1

ABSTRACT: Sequential water reuse by various users, i.e., municipal, industrial, agricultural, is common practice in all river systems. In the arid and semiarid western United States where streams are not large and water demands are high relative to the virgin water supply, the practice causes a reduction in stream flow and an increase in stream salinity. This paper outlines a quick and easy application of the materials balance principle to approximate the effects of increasing the level of sequential reuse on residual stream flow and salinity.     

Post-metamorphic growth of the arms in Ophiophragmus filograneus (Echinodermata: Ophiuroidea) from Tampa Bay,Florida (USA)

Juveniles of the burrowing amphiurid Ophiophragmus filograneus from Tampa Bay, Florida (USA) exhibit a growth pattern unreported in the ophiuroid literature. Two nonadjacent arms grow at a greater rate than the other three arms. This phenomenon might be a developmental adaptation to avoid salinity and temperature fluctuations in surface waters of the shallow-water environment which O. filograneus inhabits. It is proposed that concentration of growth into 2 of the 5 arms permits earlier descent of the disc into the substratum with continued ability to feed on the surface with the arm tips. Larger specimens show a gradual equalization of arm lengths. Changes in growth rates and cropping of the longer arms by breakage and predation might account for such eventual equalization.     

Changes in herd stallions among feral horse bands and the absence of forced copulation and induced abortion

Summary Forced copulation and induced abortion were investigated in a herd of feral horses inhabiting a coastal barrier island. Eight mares were diagnosed pregnant in August and October 1989 by means of urinary and fecal steroid metabolites, prior to documented changes in herd stallions. These mares were observed for harassment and forced copulation by the new stallions and for the presence of foals during the spring and summer of 1990. No incidents of harassment or attempts at forced copulation were witnessed and seven of the eight mares produced foals in 1990. These data indicate that forced copulation and induced abortion are not common events among all feral horse herds and suggest reinvestigation of this hypothesized phenomenon.itOffprint requests to: J.F. Kirkpatrick     

Dueling Land Ethics: Uncovering Agricultural Stakeholder Mental Models to Better Understand Recent Land Use Conversion

The aim of this paper is to investigate how alternative land ethics of agricultural stakeholders may help explain recent land use changes. The paper first explores the historical development of the land ethic concept in the United States and how those ethics have impacted land use policy and use of private lands. Secondly, primary data gathered from semi-structured interviews of farmers, ranchers, and influential stakeholders are then analyzed using stakeholder analysis methods to identify major factors considered in land use decisions, priorities of factors of each group, and to define relevant mental models describing each group’s view of the land ethic concept. Results show that these stakeholder groups prioritize land use factors qualitatively differently and possess strikingly different land ethics. It is concluded that shifts in stakeholder land ethics have contributed to recent land use changes. Lastly, we discuss how current agricultural policy sends mixed signals about preferred land use and the potential ramifications based on the different land ethics we’ve described.     

UraniumVI sorption behavior on silicate mineral mixtures

UraniumVI sorption experiments involving quartz and clinoptilolite, important mineral phases at the proposed US nuclear waste repository at Yucca Mountain, NV, were conducted to evaluate the ability of surface complexation models to predict UVI sorption onto mineral mixtures based on parameters derived from single-mineral experiments. The experiments were conducted at an initial UVI aqueous concentration of approximately 2.0 x 10(-7) mol.l-1 (0.1 mol.l-1 NaNO3 matrix) and over the pH range approximately 2.5 to approximately 9.5. The UVI solutions were reacted with either quartz or clinoptilolite only, or with mixtures of the two minerals. The experiments were carried out under atmospheric pCO2(g) conditions (in loosely capped containers) or under limited pCO2(g) (in capped containers or in a glove box). Data from sorption experiments on quartz at atmospheric pCO2 conditions were used to derive UVI binding constants for a diffuse-layer surface complexation model (DLM). The DLM was then used with surface area as a scaling factor to predict sorption of UVI onto clinoptilolite and clinoptilolite/quartz mixtures under both atmospheric and low pCO2 conditions. The calculations reproduced many aspects of the pH-dependent sorption behavior. If this approach can be demonstrated for natural mineral assemblages, it may be useful as a relatively simple method for improving radionuclide transport models in performance-assessment calculations.     

Source separation recycling schemes: A survey

Municipal waste arisings continued to increase during the 1970s in all the industrialized economies. Currently, in the midst of a severe international economic recession, the continuing escalation in the costs of waste disposal poses significant problems for municipal authorities. With the data constraints firmly in mind, this paper estimates the secondary materials supply potential of the municipal waste stream. The calculations suggest that a significant supply potential remains to be utilized despite ‘respectable’ overall recycling rates in most industrial economies. Resource recovery options can be divided into ‘low technology’ source separation schemes and ‘high technology’ mechanical separation schemes. The authors concentrate on the former option and appraise (on the basis of social cost-benefit analysis) a number of schemes that have operated in both Europe and North America.