GROUNDWATER CONTAMINATION BY NEMATICIDES: INFLUENCE OF RECHARGE TIMING UNDER PINEAPPLE CROP1

ABSTRACT: Toxic organic compounds, such as DBCP, EDB, and c TCP, that are associated with pineapple cultivation in Hawaii have been discovered in drinking water wells on Oahu. In order to reach and contaminate the Pearl Harbor aquifer, pesticides must be transported quickly downward away from the soil surface prior to complete volatilization, degradation, or adsorption of residuals. This paper assesses the role of pesticide application timing relative to subsequent rainfall-induced recharge events in determining the amount and extent of chemical leaching from the soil. A water balance model for a pineapple crop is developed to estimate the time series of recharge from two fields for which soil contamination profiles are available. In general, the amounts of DBCP, EDB, and TCP found in the soil profiles of the two fields are consistent with expectations of leaching based on an analysis of the recharge time series. The results indicate that recharge during and immediately following the application of pesticides is important in determining whether groundwater contamination will result.     

Environmental gradients in northwest freshwater wetlands

Wetland environmental characteristics are examined to determine their spatial and temporal relationships. Two very different Oregon freshwater wetlands provided a range of wetland types. Results are evaluated to determine the possible use of environmental characteristics in defining wetlands and their boundaries. Representative physical, hydrological, and edaphic properties were periodically measured in microplots along upland/wetland transects. A multivariate approach is stressed in the data analysis; correlation, cluster analysis, and principal components analyses were used. The results indicate the environmental characteristics change in a quantifiable manner both spatially and temporally. The controlling mechanism is moisture, spatially in terms of the upland/wetland transect and temporally with respect to seasonal response. These changes do not correlate well with vegetation. Several hypotheses are offered as an explanation. Correlation within environmental characteristics is variable but definite patterns are discernible. These data suggest both single and combinations of environmental characteristics that could serve as keys in wetland identification and boundary determination. However, before extensive use is made of this information additional long-term monitoring of wetland environmental characteristics will be required.     

ISOLATION AND DETECTION OF GIARDIA CYSTS FROM WATER USING DIRECT IMMUNOFLUORESCENCE1

ABSTRACT: A water-sampling apparatus used for the isolation and detection of Giardia cysts in water has been designed and tested. The sampling apparatus uses one of a variety of pumps or waterline pressure to move water through a filter. Two of the optional pumps are lightweight enough to make the apparatus portable and thus suitable for sampling in remote areas. This technique of sample processing produces good cyst recovery in much less time than is required with previously established methods. Giardia cysts are identified using direct immunofluorescence.     

AN ANTIDEGRADATION POLICY FOR PRESERVING SURFACE WATER QUALITY IN FLORIDA1

ABSTRACT: As part of its overall system for protecting aquatic systems from unnecessary degradation, the State of Florida provides special protection for water bodies of unusual importance. Such water bodies are designated as “Outstanding Florida Waters” (OFW5). New discharges to OFWs are possible only if certain stringent criteria are met. A new point source direct discharge to an OFW is usually not allowed if it would cause any lowering of ambient water quality. A new indirect discharge (upstream from an OFW boundary) may be allowed only if it would not significantly degrade the OFW. To date, the advantages of the OFW system have clearly outweighed the disadvantages, and OFW designations are helping to protect Florida's most valuable waters from additional degradation. Florida's system could be a useful model for other jurisdictions wanting to provide special protection to special water bodies.     

Restoring naturalness to national parks

National park resource management planning requires ecological information describing the objectives to be achieved. This information must be quantitative and unambiguous. Since most acts creating United States national parks, beginning with the Yellowstone National Park Act of 1872, specify that these parks should be maintained in a natural condition, resource management objectives for each national park must be defined in terms of quantitative standards of naturalness. Such quantitative standards of naturalness do not yet exist for any national park in the United States. Although this article focuses on US national parks, the same problem exists in national parks, reserves, and wilderness areas throughout the world. The physical evidence needed to develop quantitative standards of naturalness is rapidly disappearing because of the effects of management fires, wildfires, decomposition, successional changes, and other disturbances. Therefore, a nationwide rescue ecology program is recommended to recover as much remaining ecological information as possible before it is lost. This information is essential for developing quantitative standards to restore naturalness to national parks.     

Precursors of employee turnover: A multiple-sample causal analysis

Two models of the nature of linkages among precursors of voluntary turnover were examined using four distinct samples. A model which includes both job satisfaction and organizational commitment as exogenous variables leading to one's intention to resign was shown to provide results which support its usage in future research. Analyses of longitudinal data for precursors across two points in time, before turnover, however, provided only weak support for causality.     

Public opinion and interest group positions on open-space issues in Albuquerque,New Mexico,USA: Implications for resource management

The purpose of this research was to elicit and compare the open-space preferences of citizens and openspace experts in Albuquerque, New Mexico, USA. A randomly selected sample of 492 citizens and 35 open-space experts participated in a telephone survey during May 5–18, 1986. The following hypothesis was tested and used as a guideline for the study:HO1: There is no significant difference between respondents' status and preference for open space in Albuquerque, New Mexico.The hypothesis was rejected. Findings confirmed respondents' status affected preference for open space. Of the eight issues on which the citizen and expert groups were compared, five recorded significant differences in response profiles. The open-space expert group was significantly more supportive of using open space to accommodate offroad vehicle facilities, wildlife preserves, a citywide recreational trail, and a trail system along the arroyos and city ditches. The citizen sample was significantly more supportive of using open space to accommodate overnight camping facilities. Both groups equally supported using open space to accommodate an outdoor amphitheater, outdoor education facilities, and rafting, kayaking, and canoeing facilities.The finding indicated that expert preferences did not represent an aggregate of citizen preferences for managing open-space resources. Understanding both expert and citizen positions will facilitate decision-making processes and help resolve environmental disputes.     

Basic hydrologic studies for assessing impacts of flow diversions on riparian vegetation: Examples from streams of the eastern Sierra Nevada,California, USA

As the number of proposals to divert streamflow for power production has increased in recent years, interest has grown in predicting the impacts of flow reductions on riparian vegetation. Because the extent and density of riparian vegetation depend largely on local geomorphic and hydrologic setting, site-specific geomorphic and hydrologic information is needed. This article describes methods for collecting relevant hydrologic data, and reports the results of such studies on seven stream reaches proposed for hydroelectric development in the eastern Sierra Nevada, California, USA. The methods described are: (a) preparing geomorphic maps from aerial photographs, (b) using well level records to evaluate the influence of streamflow on the riparian water table, (c) taking synoptic flow measurements to identify gaining and losing reaches, and (d) analyzing flow records from an upstream-downstream pair of gages to document seasonal variations in downstream flow losses. In the eastern Sierra Nevada, the geomorphic influences on hydrology and riparian vegetation were pronounced. For example, in a large, U-shaped glacial valley, the width of the riparian strip was highly variable along the study reach and was related to geomorphic controls, whereas the study reaches on alluvial fan deposits had relatively uniform geomorphology and riparian strip width. Flow losses of 20% were typical over reaches on alluvial fans. In a mountain valley, however, one stream gained up to 275% from geomorphically controlled groundwater contributions.     

PATTERNS OF WATERSHED MONTHLY RUNOFF1

ABSTRACT: Two dimensional sliding polynomials were adapted to pattern analysis of watershed monthly rainfall and runoff. Contours of runoff in the two-dimensional space of time and rainfall are constructed on a grid of 16 nodes whose values are determined by least squares. This method is form free, hence derived patterns are not biased to selected functional forms, but can directly represent the smoothed data. Values of the nodes are localized averages of the data constrained by required mathematical continuity across the grid of values. An advantage of the method is that the standard deviation can be calculated for each node, thus producing patterns of uncertainty of the deterministic component revealed by the data.