Tax policy and secondary material use

Legislative interest in policies to stimulate resource recovery has pointed out the need for an analysis of the determinants of materials flows. This paper characterizes the flows of virgin and secondary materials and explores in detail points where the two materials become substitute commodities. Econometric models specified at these points of substitution in the wastepaper and scrap steel industries are used to analyze various policy options being considered by Congress.     

A Method for Setting the Size of Plant Conservation Target Areas

Abstract: Realistic time frames in which management decisions are made often preclude the completion of the detailed analyses necessary for conservation planning. Under these circumstances, efficient alternatives may assist in approximating the results of more thorough studies that require extensive resources and time. We outline a set of concepts and formulas that may be used in lieu of detailed population viability analyses and habitat modeling exercises to estimate the protected areas required to provide desirable conservation outcomes for a suite of threatened plant species. We used expert judgment of parameters and assessment of a population size that results in a specified quasiextinction risk based on simple dynamic models. The area required to support a population of this size is adjusted to take into account deterministic and stochastic human influences, including small-scale disturbance, deterministic trends such as habitat loss, and changes in population density through processes such as predation and competition. We set targets for different disturbance regimes and geographic regions. We applied our methods to Banksia cuneata, Boronia keysii, and Parsonsia dorrigoensis, resulting in target areas for conservation of 1102, 733, and 1084 ha, respectively. These results provide guidance on target areas and priorities for conservation strategies.     

Influence of kinship on helping behavior in Galápagos mockingbirds

Summary The social organization of the Galápagos mockingbird (Nesomimus parvulus) in unusual in that groups frequently include more than one breeding pair (plural breeding), and helping behavior is flexible: some birds neither breed nor help, while others do both. To investigate the influence of kinship on helping behavior, I categorized each bird as a helper or non-helper with respect to each nest within its group where it had an opportunity to help. The incidence of helping varied with relatedness: more birds helped when nestlings available to be fed were close relatives than when not. This result was independent of a higher incidence of helping among males than among females and of variation with age among males. Proportionally more nonbreeding than breeding males helped, but breeding and nonbreeding females helped equally infrequently; breeders helped most often after their own nests failed. The incidence of helping was highest among birds with opportunities to feed offspring of breeders that had fed the potential helper as a nestling, suggesting a mechanism for kin discrimination based on associative learning. Juveniles with opportunities to choose among alternative recipients preferentially fed closely related nestlings, but insufficient information was available to determine if adults also did so. Kinship did not influence the rate at which nestlings were fed by helpers. Juveniles fed nestlings at lower rates than did adult helpers, but helping effort was otherwise unaffected by age, sex, or relatedness. Limitation of help to former feeders functions as a mechanism for directing aid to relatives in a plural breeding system where degrees of kinship vary among potential recipients within the same group.     

Genital abnormalities in white-tailed deer (Odocoileus virginianus) in west-central Montana: pesticide exposure as a possible cause

From spring, 1996, to early spring, 2000, accident-killed and injured white-tailed deer, Odocoileus virginianus, in the Bitterroot Valley of west-central, Montana, U.S.A., were collected and examined for genital abnormalities at the Bitterroot Wildlife Rehabilitation Center. Of the 254 male deer examined, 133 were fawns aged 3 months to 1 yr, 29 were 1 to 1 1/2 yrs of age, and 92 were 1 1/2 to 3 yrs of age. Approximately 33% were normal; the remaining 67% showed varying degrees of apparent genital developmental anomalies, specifically mispositioned and undersized scrota and ectopic testes, and this percentage held through all age groups. The sex ratio of fawns and fetuses was skewed towards males, significantly so for the 1996 fawn cohort and for the total of all fawns and fetuses in the study. Although possible causes of the genital anomalies, centering on endocrine disrupting pesticides, are discussed, no conclusions of cause and effect can be currently justified.     

Successful application of monitored natural attenuation in a surficial aquifer

Groundwater investigations conducted since 1988 at a Tennessee Department of Environment and Conservation (TDEC) Voluntary Oversight and Assistance Program (VOAP) site located in Millington, Tennessee, have defined the lateral and vertical extent of site chemicals of concern (COCs) consisting of tetrachloroethene (PCE), trichloroethene (TCE), and associated degradation products. Results of a groundwater remedial investigation determined that aquifer conditions were favorable for anaerobic degradation of COCs through reductive dechlorination. A subsequent groundwater feasibility study determined that monitored natural attenuation (MNA) coupled with long‐term groundwater monitoring was the most effective and suitable remedial option for the site. A Record of Decision was issued by the TDEC VOAP approving MNA and long‐term groundwater monitoring as the remedial option for the site, a first for such a site in Tennessee involving chlorinated organics. A groundwater fate and transport model (the 1998 model) developed during the RI was used as the basis for the MNA remedy. Analytical data from 1998 to 2008 indicate COCs in former high‐concentration areas continue to degrade at rates consistent with or ahead of the 1998 model predictions. Evidence of reductive dechlorination is also supported by the continued presence of breakdown products—specifically, vinyl chloride and ethene (terminal endpoint of PCE breakdown through reductive dechlorination). The continued detection of breakdown products along the flow‐path wells also confirms the effectiveness of the MNA remedy at the site. Current analytical data indicate that COC plumes beneath the site are not migrating and are actually retracting. © 2010 Wiley Periodicals, Inc.     

Degradation of poly(β-hydroxyalkanoates) and polyolefin blends in a municipal wastewater treatment facility

Six types of plastics and plastic blends, the latter composed at least partially of biodegradable material, were exposed to aerobically treated wastewater (activated sludge) to ascertain their biodegradability. In one study, duplicate samples of 6% starch in polypropylene, 12% starch in linear low-density polyethylene, 30% polycaprolactone in linear low-density polyethylene, and poly(-hydroxybutyrate-co-hydroxyvalerate) (PHB/V), a microbially produced polyester, were exposed to activated sludge for 5 months, and changes in mass, molecular weight average, and tensile properties were measured. None of the blended material showed any sign of degradation. PHB/V, however, showed a considerable loss of mass and a significant loss of tensile strength. In a second study, PHB/V degraded rapidly, but another type of microbial polymer which forms a thermoplastic elastomer, poly(-hydroxyoctanoate), did not degrade. These results illustrate the potential for disposal and degradation of PHB/V in municipal wastewater.     

Effect of compost treatment of sewage sludge on nitrogen behavior in two soils

This work aims to evaluate the effects of compost treatment of digested sewage sludge on nitrogen behavior in two soils, a Spodosol and an Oxisol soil. Digested sewage sludge was composted with sawdust and woodchips, diluting the total nitrogen to one-fourth (dry mass basis) of its original value. Then, sludge and compost were added to the two soils on an equivalent dry weight basis to consider the risk of NO3- -N leaching. Compost treatment of sewage sludge has slowed down the release of mineral-N to half in the Spodosol and to one-third in Oxisol soil. As a result, NO3- -N concentrations in soils incubated with compost were less than half of the amounts found from soils incubated with digested sludge. Estimates were made of the maximum monthly nitrate to leach from the four combinations of soil and sludge treatment. Application of digested sludge, at a higher nitrogen application rate, resulted in a higher nitrate leaching potential than application of the compost product. Soil type also played an important role, with the Oxisol having slightly higher estimated leaching potential than the Spodosol. The higher nitrate release rate in the Oxisol is counterbalanced by its higher field capacity to lessen the expected difference between the two soils.     

Production, Purification and Activity of an Extracellular Depolymerase from Aspergillus fumigatus

A strain of Aspergillus fumigatus, which was observed to rapidly degrade poly-3-hydroxybutyrate (PHB) in a leaf compost, was found to secrete an extracellular hydrolase when grown on PHB as the sole carbon source. Isolation and characterization of the PHB hydrolase (depolymerase) from this fungus revealed that the enzyme had a molecular weight of 57 kDa, an isoelectric point of 7.2, and a PHB hydrolysis activity maxima which occurred at 70°C and pH 8.0. Affinity labeling experiments suggested that this fungal hydrolase is a type of serine esterase. The cyclic trimers of 3-hydroxybutyrate were found to reversibly inhibit the enzymes.