SEDIMENT TRANSPORT DURING A CONTROLLED RESERVOIR RELEASE1

The transport of bedload and suspended sediments and particulate organic matter was evaluated in Huntington Creek, Utah, during a controlled release of water from Electric Lake Reservoir from August 7–10, 1979. Effects of the release on channel geometry and riffle composition also were assessed. Bedload transport rates increased from zero to 1,650 and 1,500 kg/hr at two cross sections as discharge was increased from 0.4 to 4.9 m³/s; transport rates then decreased erratically as discharge was held constant. Cross section measurements and sediment size analysis indicate that flows were insufficient to transport riffle sediments. Rapid increases in the transport rates of suspended sediments and particulate organic matter also occurred during rising discharge and again decayed when discharge became constant. Suspended sediment concentrations for samples obtained with an automatic pumping sampler were generally less than those found for samples obtained with a DH-48 sampler. Biological measurements still are needed to determine if such a release can improve fisheries habitat by removing fine sediments.     

PREPLANTING SOIL MOISTURE USING PASSIVE MICROWAVE SENSORS1

ABSTRACT: Accurate assessment of preplanting soil moisture conditions is necessary for good agricultural management, and can have a significant influence on crop yield in the Texas Panhandle region. The Texas High Plains Underground Water Conservation District invests considerable time and money in developing a soil moisture deficit map each year in the hopes of achieving optimal use of irrigation water. Microwave sensors are responsive to surface soil moisture and, if used in this application, can provide timely and detailed information on root zone soil moisture. For this reason, an experiment was conducted in 1984 to evaluate the potential of aircraft-mounted passive microwave sensors. Microwave radiometer data were collected over a 2700 km² area near Lubbock, Texas, with a processed resolution of 0.32 km². These data were ground registered and converted to estimates of soil moisture using an appropriate model and land cover and soil texture information. Analyses indicate that the system provides an efficient means for mapping variations in soil moisture over large areas.     

DESIGN FOR A STABLE CHANNEL IN COARSE ALLUVIUM FOR RIPARIAN ZONE RESTORATION1

Geomorphic, hydraulic and hydrologic principles are applied in the design of a stable stream channel for a badly disturbed portion of Badger Creek, Colorado, and its associated riparian and meadow complexes. The objective is to shorten the period of time required for a channel in coarse alluvium to recover from an impacted morphologic state to a regime condition representative of current watershed conditions. Channel geometry measurements describe the stream channel and the normal bankfull stage in relatively stable reaches. Critical shear stress equations were used to design a stable channel in noncohesive materials with dimensions which approximate those of less disturbed reaches. Gabion controls, spaced at approximately 300 m intervals, are recommended to help reduce the chance of lateral migration of the newly constructed channel. Controls are designed to allow for some vertical adjustment of the channel bed following increased bank stability due to revegetation. The flood plain is designed to dissipate flood flow energy and discourage multiple flood channels. The channel has approximately a 90 percent chance of remaining stable the first two years following construction, the time estimated for increased stability to occur due to revegetation.     

Transition to large-scale organic vegetable production in the Salinas Valley, California

Studying the management strategies suited to large-scale organic production, particularly during the mandated 3-year transition period from conventional management, is a unique research challenge. Organic production traditionally relies on small, diverse plantings and complex management responses to cope with soil fertility and pest pressures, so research should represent decision-making options of an organic grower at the farm scale. This study analyzes crop, soil, pest and management changes during the organic transition period on two ranches (40 and 47 ha) in the Salinas Valley, California in cooperation with a large conventional vegetable producer, Tanimura and Antle, Inc. Permanent transects were established across the two ranches at the onset of adoption of organic practices, and soil and plants were sampled at harvest of almost all crops, while all management operations were recorded by the co-operator. The 10 ha blocks were divided into many small plantings, and 17 different cash crop and cover crop species were planted during the transition period. Management inputs consisted of a range of organic fertilizers and amendments, sprinkler and drip irrigation, cultivation and hand-hoeing, and several types of organic pesticides. Results from the 3-year period followed these general trends: increase in soil biological indicators (microbial biomass and arbuscular mycorrhizae), low soil nitrate pools, adequate crop nutrients, minor disease and weed problems, and sporadic mild insect damage. Multivariate statistical analyses indicated that some crops and cultivars consistently produced higher yields than others, relative to the maximum yield for a given crop. Multi-factor contingency tables showed clear differences in insect and disease damage between crop taxa. Although Tanimura and Antle, Inc. used some of the principles of organic farming (e.g., crop diversity, crop rotation, and organic matter (OM) management), they also relied on substitution-based management, such as fertigation with soluble nutrients, initially heavy applications of organic pesticides, and use of inputs derived from off-farm sources. Their initial production of a large number of crop taxa in small plantings at staggered intervals proved to be an effective strategy for avoiding risks from low yields or crop failure and allowed them to move towards a smaller number of select, successful crops towards the end of the transition. This study demonstrates the feasibility of large-scale producers to transition to organic practices in a manner that was conducive to both production goals and environmental quality, i.e., increased soil C pools, low soil nitrate, and absence of synthetic pesticides.     

Insect chemical communication: Pheromones and exocrine glands of ants

Summary Chemical communication plays a very important role in the lives of many social insects. Several different types of pheromones (species-specific chemical messengers) of ants have been described, particularly those involved in recruitment, recognition, territorial and alarm behaviours. Properties of pheromones include activity in minute quantities (thus requiring sensitive methods for chemical analysis) and specificity (which can have chemotaxonomic uses). Ants produce pheromones in various exocrine glands, such as the Dufour, poison, pygidial and mandibular glands. A wide range of substances have been identified from these glands.     

Reclamation of the Urad molybdenum mine,Empire, Colorado

The Urad Mine, located at an elevation of 10,400 feet near the Continental Divide in central Colorado, was operated from 1967–1974 by AMAX Inc. Mine related activities disturbed approximately 234 acres, of which two tailing deposition areas comprised 121 acres. Comprehensive reclamation was initiated prior to mine closure in 1974 and was completed in 1980.Conventional revegetation techniques were implemented on typical disturbances while the tailing areas were reclaimed with the aid of three waste products. Mine waste rock was used to cap the tailing areas, and sewage and wood wastes were used to convert the rock into a rudimentary soil. The rock was revegetated and the vegetation is now permanent and selfsustaining.     

The roles of nicotine and natural enemies in determining larval feeding site distributions of Manduca sexta L. and Manduca quinquemaculata (Haworth) on tobacco

Summary. Field observations indicated that hornworms select feeding sites non-randomly on tobacco. We tested the hypotheses that differences in feeding site locations of larvae of Manduca sexta L. and Manduca quinquemaculata (Haworth) (Lepidoptera: Sphingidae) on tobacco could be explained by differential nicotine concentrations within plants and leaves, species-specific responses to nicotine, or pressure exerted by natural enemies. Results showed that third-instar larvae of M. sexta fed more proximally and centrally on the leaf, whereas M. quinquemaculata fed more distally. Within-plant selection of leaves did not differ; both species selected leaves in the middle region of the plant. Nicotine concentrations in a high nicotine genotype, NC95, varied within each leaf, increasing 2—3 fold from the basal to apical portion of the leaf, and within each plant, increasing 7—10 fold from the first fully expanded leaf to the twelfth (lowest) leaf. In laboratory bioassays, both Manduca species responded to nicotine as a feeding deterrent. Electrophysiological studies demonstrated that gustatory organs of both species responded to nicotine at concentrations found in tobacco leaves and that M. quinquemaculata generally showed a less vigorous response to nicotine than M. sexta. Field mortality of M. sexta due to parasitism by Cotesia congregata (Say) and to parasitism and predation combined differed among feeding sites; predation alone did not. Results suggest that although nicotine concentration and species specific responses to nicotine play a role in determining feeding site locations, pressure exerted by natural enemies, especially parasitism by C. congregata, is more important. Received 22 February 2000; accepted 20 July 2001.     

Polynuclear aromatic hydrocarbon contaminants in oysters from the Gulf of Mexico (1986-1990)

Polynuclear aromatic hydrocarbon (PAH) contaminant concentrations in 870 composite oyster samples from coastal and estuarine areas of the Gulf of Mexico analyzed as part of National Oceanographic and Atmospheric Administration's (NOAA's) National Status and Trends (NS&T) Mussel Watch Program exhibit a log-normal distribution. There are two major populations in the data. The cumulative frequency function was used to deconvolute the data distribution into two probability density functions and calculate summary statistics for each population. The first population consists of sites with lower PAH concentration probably due to background contamination (i.e. stormwater runoff, atmospheric deposition). The second population are sites with higher concentrations of PAHs associated with local point sources of PAH input (i.e. small oil spills, etc.). The temporal pattern for the mean concentration of the populations from the Gulf of Mexico is consistent with large-scale climatic factors such as the El Ni?o cycles which affect the precipitation regime.     

An Interactive, Spatial Inventory of Environmental Data in the Mid-Atlantic Region

The U.S. Environmental Protection Agency (EPA) is working with federal, state, local, and non-governmental partners to produce an interactive, spatial inventory of environmental data in the mid-Atlantic region. The inventory will include maps of sampling locations, lists of measurements, and design information for hundreds of research sites and monitoring programs. It will also feature user-defined queries, resulting in customized maps that satisfy search criteria. (For example, "Display the probability-based surveys that measure dry deposition and nutrient availability in soils"). The inventory will be used in an interagency pilot study, instigated by the National Science and Technology Council's Committee on the Environment and Natural Resources, to integrate environmental monitoring and research activities. The inventory will also provide information for a regional ecological assessment led by EPA Region 3 and the Office of Research and Development. In addition, an interagency consortium will use the inventory to identify suitable field data for assessing the accuracy of satellite imagery. In each of these three applications, the inventory will be tested and evaluated as a potential prototype for completing additional regions of the U.S. Maintained as an Oracle database, the inventory is accessible on the internet at http://www.epa.gov/monitor/. Currently, ten inventory records are on-line for demonstration. The complete federal inventory of approximately 180 records will be accessible on-line by October, 1997; approximately 200 state, local and non-governmental records are scheduled for on-line access by April, 1998.     

Diagnosis and prenatal diagnosis of epidermolysis bullosa herpetiformis (Dowling-Meara) in a mother,two affected children,and an affected fetus

In utero skin biopsy was performed on a fetus at risk of an uncertain form of epidermolysis bullosa (EB). The mother had produced two affected offspring diagnosed variously as having junctional or dystrophic EB. The two offspring and the fetus were products of different fathers. The mother claimed to have no disease and on clinical examination was without blisters. Examination of the fetal skin biopsy by light and electron microscopy revealed separation of the epidermal sheet from the majority of the biopsy sample, although occasional remnants of basal cells remained associated with the basement membrane. Aggregations of keratin filaments were observed within basal cells of the detached epidermis and in the attached basal cell remnants. The diagnosis was thus suggested to be epidermolysis bullosa Dowling-Meara. Re-review of the clinical and laboratory data from the affected infants revealed a clinical and histological pattern consistent with this diagnosis. Further discussion with the mother revealed that her skin had blistered as a child and that she presently had hyperkeratotic palms and soles. This history is consistent with the autosomal dominantly inherited epidermolysis bullosa herpetiformis (Dowling-Meara). This is the first reported prenatal diagnosis of EB Dowling—Meara. The morphological criteria of intraepidermal blistering and clumped keratin filaments within basal and immediately suprabasal cells characteristic of an affected individual postnatally also identified an affected fetus. There is, however, insufficient experience to be certain that these findings will hold from region to region in the body or among all affected fetuses, and thus prenatal diagnosis on a morphological basis should still be made with caution.