LEAD AND CADMIUM ASSOCIATED WITH SALTWATER INTRUSION IN A NEW JERSEY AQUIFER SYSTEM1

ABSTRACT: The U.S. Geological Survey collected ground-water samples from the upper and middle aquifers of the Potomac-Raritan-Magothy aquifer system in a 400-square-mile area of New Jersey from 1984 through 1986. Concentrations of lead were greater than the U.S. Environmental Protection Agency maximum contaminant level (MCL) of 50 micrograms per liter in water from 16 of 239 wells. The cencentrations of cadmium were greater than the MCL of 10 micrograms per liter in water from 10 to 241 wells. One-half of the wells that exceeded the lead MCL were in known areas of saltwater intrusion, as were all 10 wells that exceeded the cadmium MCL. The association of elevated concentrations of these metals with elevated concentrations of chloride indicates a mochanism related to saltwater intrusion.     

THE RHIZOSPHERE ECOLOGY OF SUBMERSED MACROPHYTES1

ABSTRACT: This article, based on a review of the literature, examines several aspects of the rhizosphere ecology of submersed macrophytes. These include the role of the rhizosphere microflora in affecting plant growth through influences on nutrient availability and production of plant growth regulating compounds. Interactions between components of the sediment microflora and plant roots are considered in relation to plant nitrition and growth. Possible applications of this information to the management of submersed macrophytes are considered.     

Trends and issues in land and water resources management: Setting the agenda for change

The classical model of a paradigm shift is used to explore changes that are occurring in public lands and water resources management. Recent policy developments suggest that the traditional paradigm, which is characterized by sustained yield, is in the process of being invalidated. While no new paradigm has been fully accepted, the emerging paradigm does appear to be based on two principles: ecosystem management and collaborative decision making. Implementation of these two principles is likely to require extensive revision of traditional management practices and institutions. Failure to address these issues could result in adoption of the rhetoric of change without any lasting shift in management practices or professional attitudes.     

Drainage Investment and Wetlands Loss: an Analysis of the National Resources Inventory Data

The United States Soil Conservation Service (SCS) conducts a survey for the purpose of establishing an agricultural land use database. This survey is called the National Resources Inventory (NRI) database. The complex NRI land classification system, in conjunction with the quantitative information gathered by the survey, has numerous applications. The current paper uses the wetland area data gathered by the NRI in 1982 and 1987 to examine empirically the factors that generate wetland loss in the United States. The cross-section regression models listed here use the quantity of wetlands, the stock of drainage capital, the realty value of farmland and drainage costs to explain most of the cross-state variation in wetland loss rates. Wetlands preservation efforts by federal agencies assume that pecuniary economic factors play a decisive role in wetland drainage. The empirical models tested in the present paper validate this assumption.     

Environmental considerations for levees and floodwalls

Levees and floodwalls are used extensively throughout the United States for flood control. Levee projects often lack ecological, recreational, and aesthetic values, except for incidental fish and wildlife benefits derived from borrow pits and recreational facilities found in some urban settings. In recent years increased environmental concern within construction agencies and greater responsiveness to public opinion have resulted in increasing numbers of levee projects designed, built, and maintained with environmental objectives in mind. This paper reviews environmental concepts successfully employed on levee projects constructed in recent years by the US Army Corps of Engineers. Some of the most innovative concepts are described and illustrated and design considerations are discussed.     

Determining residential firewood consumption

Household firewood use has become increasingly popular in the United States over the past few years. Significant problems remain in estimating firewood consumption. Methods of determining the amount of wood consumed vary from state to state. Units used for measuring firewood vary, but the cord remains the researcher's favorite. Factors used for converting other units, such as pickup truck loads to cords also vary. People who do not use firewood are less likely to respond to mailed surveys, resulting in potential overestimates of statewide consumption. This paper identifies some problems associated with estimating household firewood consumption and recommends methods of dealing with them.     

In situ agrobiodiversity conservation: Examples from Nepal,Turkey and Switzerland in the first decade of the convention on Biological Diversity

Applications of in situ agrobiodiversity conservation practices within agricultural production systems have the potential to reduce the risks of agricultural modernisation and enhance sustainable development. The aims and approaches for in situ conservation differ according to the requirements of communities and nations. Approaches to in situ conservation in the decade after the Convention of Biological Diversity are reviewed within the contexts of marginal agricultural systems in Nepal, Turkey and Switzerland. Numerous approaches are currently utilised, including: the informal de facto retention of agrobiodiversity; the provision of state assistance; the marketing of agrobiodiversity products; the use of technological innovations to develop local diversity; the establishment of conservation reserves; community assistance programmes and the raising of awareness of the issue amongst all sectors of societies. Emerging complementary in situ approaches applicable in the rural margins suggest a framework for effectively conserving agrobiodiversity by working with local people.     

Kinetics of biochemically driven metal precipitation in synthetic landfill leachate

This study investigates the effectiveness of using metal sulphide and carbonate precipitation mechanisms combined with a landfill‐derived mixed bacterial population. The study was conducted under controlled substrate conditions in anaerobic batch reactors. High chemical oxygen demand (COD):sulphate ratios, butyrate, propionate, and acetate were used anaerobically by bacteria for growth with associated sulphate reduction as well as sulphide and carbonate generation. Propionate and butyrate degradation occurred during sulphate reduction by sulphate‐reducing bacteria while acetate degradation was associated with methanogenesis by methanogenic bacteria. Using low COD, sulphate ratios showed limited acetate utilization, but sulphate reduction still occurred. Precipitation of Cd, Cu, Zn, Ni, and Fe sulphides occurred quickly and was completed in 15 to 30 days, while Ca, Mn, and Mg carbonates formed after 40 to 50 days and some soluble metal remained even after 120 days. The rate of metal precipitation was in the order of Cd>Cu>Zn>Ni>Fe>Mn>Mg>Ca. Bacterially mediated metal precipitation occurred slower than that recognized for chemical precipitation. These findings suggest that contaminant transport models based on chemical equilibrium metal behaviors may over‐predict metal removal by bio‐precipitation. © 2002 Wiley Periodicals, Inc.     

Channelization and levee construction in Illinois: Review and implications for management

The environmental impact of loss of natural stream and riparian habitat is of concern throughout the United States and Europe. Environmental impacts related to such activities as channelization of and levee construction along streams and rivers are particularly apparent in the Midwestern United States. The objective of the research presented here was to delineate the extent, relative degree of impact, and implications for management of channelization and levee construction along watercourses located in the state of Illinois. According to records maintained through the Illinois Streams Information System data base (Illinois Department of Conservation), nearly 25% of surface water resources in the state have been modified directly by channelization and/or levee construction. Reviews of agency records, elaboration of case histories, interviews with agency personnel, and inspections of impacted sites indicated that these alterations have occurred without the benefit of effective mitigation. Although permit records may provide suggestions for mitigation to be incorporated in the design of a particular project, permits issued generally do not require even minimal instream habitat and bank stabilization efforts in conjunction with channel alteration. Information derived from policy and case study analyses suggests that institutional constraints, rather than lack of particular understanding about mitigation, provide major barriers to protecting the state's surface water resources in terms of regulatory review, policy interpretation and implementation, and project evaluation. Recommendations for environmental management efforts regarding these and similar channel alterations are elaborated from these findings.