Assessment of denitrification gaseous end-products in the soil profile under two water table management practices using repeated measures analysis

The denitrification process and nitrous oxide (N2O) production in the soil profile are poorly documented because most research into denitrification has concentrated on the upper soil layer (0-0.15 m). This study, undertaken during the 1999 and 2000 growing seasons, was designed to examine the effects of water table management (WTM), nitrogen (N) application rate, and depth (0.15, 0.30, and 0.45 m) on soil denitrification end-products (N2O and N2) from a corn (Zea mays L.) field. Water table management treatments were free drainage (FD) with open drains and subirrigation (SI) with a target water table depth of 0.6 m. Fertility treatments (ammonium nitrate) were 120 kg N ha(-1) (N120) and 200 kg N ha(-1) (N200). During both growing seasons greater denitrification rates were measured in SI than in FD, particularly in the surface soil (0-0.15 m) and at the intermediate (0.15-0.30 m) soil depths under N200 treatment. Greater denitrification rates under the SI treatment, however, were not accompanied with greater N2O production. The decrease in N2O production under SI was probably caused by a more complete reduction of N2O to N2, which resulted in lower N2O to (N2O + N2) ratios. Denitrification rate, N2O production and N2O to (N2O + N2) ratios were only minimally affected by N treatments, irrespective of sampling date and soil depth. Overall, half of the denitrification occurred at the 0.15- to 0.30- and 0.30- to 0.45-m soil layers, and under SI, regardless of fertility treatment level. Consequently, sampling of the 0- to 0.15-m soil layer alone may not give an accurate estimation of denitrification losses under SI practice.     

Biodegradation of Coproducts from Industrially Processed Corn in a Compost Environment

Information pertaining to biodegradability of renewable polymeric material is critical for the design and development of single-use biodegradable consumer products. The rate and extent of biodegradation of corn fiber, corn zein, cornstarch, distillers grain, and corn gluten meal were evaluated in compost environments under variable temperature, pH, and moisture conditions. Generally, composts with higher temperature (40°C), neutral pH (7.0), and 50%–60% moisture appeared to be ideal for corn coproduct biodegradation, particularly for corn gluten meal and corn zein. Low moisture conditions slowed biodegradation considerably, but degradation rates improved when moisture content increased up to 60%. Thereafter, increased moisture particularly slowed the degradation of corn gluten meal and corn zein, whereas cornstarch degradation remained unaffected. At low pH (4.0) and high pH (11.0) the rate of degradation of most coproducts was slowed somewhat. Cornstarch degradation was slower at pH 7.0, but degradation improved with increased temperatures. Increase in compost temperature from 25 to 40°C (in 5°C increments) also improved biodegradation of corn fiber and distillers grain. Addition of 1% urea to compost as a nitrogen source decreased the extent of biodegradation nearly 40% for corn gluten meal and corn zein, and 20% for cornstarch samples. Treatment of compost with 0.02% azide inhibited biodegradation of all coproducts, suggesting that the presence of metabolically active microbial cells is required for effective degradation of biobased materials in a compost environment.     

ISO 14001 in state regulatory offices: A survey of activities

Is ISO 14001 just for the private sector? The answer is definitely “No.” The survey in this article was conducted to better understand how ISO 14001/Environmental Management Systems (EMSs) was being addressed by state agencies around the country. The survey goals were to determine where the focus on ISO 14001/EMSs is within state government, what the level of interest is, and how far states have progressed toward some form of use or recognition of ISO 14001. During the months that this survey was conducted, the progress at the state and federal levels was remarkable. Many states are aggressively moving forward and encouraging the investigation of ISO 14001 implementation. There is a well coordinated effort between several states (the Multi-State Working Group) to gather data on ISO 14001 effectiveness in a consistent manner. The cooperation between EPA and the states is beginning to solidify, with federal dollars going to state-managed pilot programs, and EPA has stepped forward with a more organized effort led by the Office of Reinvention.     

Pastoralists' responses to variation of rangeland resources in time and space.

We explore the response of pastoralists to rangeland resource variation in time and space, focusing on regions where high variation makes it unlikely that an economically viable herd can be maintained on a single management unit. In such regions, the need to move stock to find forage in at least some years has led to the evolution of nomadism and transhumance, and reciprocal grazing agreements among the holders of common-property rangeland. The role of such informal institutions in buffering resource variation is well documented in some Asian and African rangelands, but in societies with formally established private-property regimes, where we focus, such institutions have received little attention. We examine agistment networks, which play an important role in buffering resource variation in modern-day Australia. Agistment is a commercial arrangement between pastoralists who have less forage than they believe they require and pastoralists who believe they have more. Agistment facilitates the movement of livestock via a network based largely on trust. We are concerned exclusively with the link between the characteristics of biophysical variation and human aspects of agistment networks, and we developed a model to test the hypothesis that such a link could exist. Our model builds on game theory literature, which explains cooperation between strangers based on the ability of players to learn whom they can trust. Our game is played on a highly stylized landscape that allows us to control and isolate the degree of spatial variation and spatial covariation. We found that agistment networks are more effective where spatial variation in resource availability is high, and generally more effective when spatial covariation is low. Policy design that seeks to work with existing social networks in rangelands has potential, but this potential varies depending on localized characteristics of the biophysical variability.     

Deep-sea bottom-living fishes at two repeat stations at 2 200 and 2 900 m in the Rockall Trough,northeastern Atlantic Ocean

Repeated sampling of deep-sea bottom-living fishes was conducted at two stations in the Rockall Trough at depths of 2 200 and 2 900 m. The 2 200 m station (M) was sampled 16 times by an Agassiz trawl between April 1978 and April 1985 and yielded 473 fish belonging to 17 species. The 2 900 m permanent station (PS) yielded 781 fish belonging to 11 species from 9 Agassiz trawls, 2 small box otter trawls, 4 semi-balloon otter trawls and 7 epibenthic sledges between March 1975 and April 1985. Macrourid fishes were numerically dominant at both stations with Coryphaenoides guentheri and Coryphaenoides (Nematonurus) armatus being the most abundant species at M and PS, respectively. In terms of biomass the morid, Antimora rostrata, was dominant at M but C. (N.) armatus was dominant at PS. The only species that showed clear evidence of a seasonal reproductive cycle was C. guentheri. Many species showed no indication of reproducing in the Rockall Trough. The diets of almost all the species are described and considered in relation to the food resources exploited. Investigations on the pelagic and benthic invertebrate faunas at these stations should reveal the extent to which the bottom-living fishes exploit the available resources.     

A field test of processed oil shale reclamation strategies designed for minimal use of limited resources

Reclamation of processed oil shale disposal areas in the arid and semi-arid regions of Utah, Colorado and Wyoming faces several challenging problems. Shallow topsoil, harsh climate and limited water supply and low suitability of processed oil shale as a plant growth medium must be addressed if any reclamation plan is to be successful.A prototype reclamation plan that addressed the harsh environmental conditions was proposed early in the development of oil shale in eastern Utah. Studies to validate the reclamation plan were initiated in 1978 on a simulated oil shale disposal area at Anvil Points, Colorado.Four native shrubs, one forb and a grass, were successfully established by planting container-grown transplants into a topsoil-filled V-shaped trench. Supplemental water was provided from an adjacent water harvesting slope. The roots of the transplanted species grew into the adjacent shale from the soil trench, thus indicating their adaptability to the adverse oil shale conditions.Support for this research was provided by the White River Shale Corporation, Salt Lake City, Utah.     

Parasite faunas,testosterone and secondary sexual traits in male red-winged blackbirds

Summary We examined associations among parasite infections, secondary sexual traits and testosterone in male red-winged blackbirds sampled at the start of the breeding season. Parasites quantified included ectoparasitic lice and mites and endoparasitic blood protozoans, nematodes, trematodes and cestodes. Secondary sexual traits that we quantified included body size, epaulet size and color, song repertoire size and song switching rate, and behavioral responses to male and female models. Overall we found few significant associations between parasites and secondary sexual traits, between secondary sexual traits and testosterone, or between parasites and testosterone. In addition, most parasite taxa appeared to infect birds independently, although the low prevalence (<50%) of many of the parasites meant that our sample sizes were too small to detect weak associations. Our most promising results were obtained for ectoparasitic mites, which tended to occur on birds uninfected with other parasites, on birds with longer epaulets, and on birds with higher levels of testosterone. Epaulet length and testosterone are both probable correlates of dominance in this species. Further research will be required to determine whether there is a causal link between the immunosuppressive effects of testosterone and the mite infections, and between testosterone, epaulet length and male mating success. Correspondence to: P. Weatherhead     

Comparative studies on the metabolism of shallow-water and deep-sea marine fishes. II. Red-muscle metabolism in shallow-water fishes

Maximal rates of oxygen consumption in vitro have been measured under standardized conditions at three test temperatures (5°, 15°, 25°C) on minced preparations of red muscle from 10 species of shallow-water marine teleost fishes. These fishes came from three different geographic areas, two with cool average water temperatures (near 15°C: coastal southern California, Galápagos Islands) and one with warm average water temperatures (near 25°C: Hawaiian Islands). The group is made up of post-juvenile or adult epipelagic fishes, which are moderately or very active in terms of their locomotor activities. A large part of the range of phylogenetic diversity among the teleosts is represented, as is the body weight range from a few grams to several kilograms. The purpose of the work is to provide part of a set of tissue-metabolism data on shallow-water fishes for future comparison with similar results from deep-sea species. Of 8 complete curves for oxygen uptake rate versus temperature (R-T curves), 6 are normal in shape (Q₁₀1.5), 1 is normal but with a low Q₁₀, and 1 is partly flat, partly normal. The differences between the species in terms of both absolute positions and slopes of the R-T curves are not related in any consistent way to any of the three testable variables: phylogenetic position, long-term adaptation temperature, and body size. The red muscles of a variety of adult epipelagic fishes, at ecologically realistic temperatures, are shown to be exceptions to the general rule that tissues of ectothermous lower vertebrates have lower metabolic rates than comparable tissues of non-torpid endothermous higher vertebrates. This circumstance probably is a major factor in the great capacities for sustained high-speed swimming shown by most epipelagic fishes. Other physiological and ecological implications of the results are discussed.