A reassessment of the mating system characteristics of the army ant Eciton burchellii

In a recent study, Denny et al. (2004a) showed that queens of the army ant, Eciton burchellii, mate with multiple males and presented estimates suggesting that they mate with more males than queens of any other ant species so far investigated. They also inferred that data were consistent with queens being inseminated repeatedly throughout their life, which would be exceptional among the social Hymenoptera and contradictory to predictions from kin selection theory. In the present study, we reanalyze these data using new software and supplement them with similar microsatellite data from other colonies of the same species. Mating frequencies in E. burchellii are indeed very high (mean observed and effective queen-mating frequencies of 12.9 each) but considerably lower than the previous estimates. We show that the number of patrilines represented in the first worker offspring of a young queen is lower than in older queens but suggest that this may be due to initial sperm clumping in the queen’s sperm storage organ, rather than to repeated inseminations. Moreover, we found no evidence for repeated mating by genotyping sequential worker generations produced by a single old queen, showing that she did not obtain new inseminations despite ample opportunities for mating.     

Comparative assessment of coal tars obtained from 10 former manufactured gas plant sites in the eastern United States

A comparative analysis was performed on eleven coal tars obtained from former manufactured gas plant sites in the eastern United States. Bulk properties analyzed included percent ash, Karl Fisher water content, viscosity and average molecular weight. Chemical properties included monocyclic- and polycyclic-aromatic hydrocarbon (PAH) concentrations, alkylated aromatic concentrations, and concentrations of aliphatic and aromatic fractions. It was found that there was at least an order-of-magnitude variation in all properties measured between the eleven coal tars. Additionally, two coal tars obtained from the same manufactured gas plant site had very different properties, highlighting that there can be wide variations in coal tar properties from different samples obtained from the same site. Similarities were also observed between the coal tars. The relative chemical distributions were similar for all coal tars, and the coal tars predominantly consisted of PAHs, with naphthalene being the single-most prevalent compound. The C(9-22) aromatic fraction, an indicator of all PAHs up to a molecular weight of approximately 276 gmole(-1), showed a strong power-law relationship with the coal tar average molecular weight (MW (ct)). And the concentrations of individual PAHs decreased linearly as MW (ct) increased up to ca. 1000 gmole(-1), above which they remained low and variable. Implications of these properties and their variation with MW (ct) on groundwater quality are discussed. Ultimately, while these similarities do allow generalities to be made about coal tars, the wide range of coal tar bulk and chemical properties reported here highlights the complex nature of coal tars.     

POLITICAL RESOLUTION OF ENVIRONMENTAL CONFLICTS1

ABSTRACT Many water resources management problems ultimately require a political decision in order to formulate a course of action to follow. Metagame analysis is a nonquantitative technique that can model the decision-making process and is used in this article to arrive at a politically feasible solution to a typical water pollution problem. The output from the linear programming formulation of the problem is used as input to the “political” metagame analysis. This allows a solution to the pollution conflict that is not only physically and economically feasible according to the linear programming analysis, but politically feasible as well.     

Assessment of environmental impacts part two: Data collection

Intervention analysis is a relatively new branch of time series analysis. The power of this technique, which gives the probability that changes in mean level can be distinguished from natural data variability, is quite sensitive to the way the data are collected. The principal independent variables influenced by the data collection design are overall sample size, sampling frequency, and the relative length of record before the occurrence of the event (intervention) that is postulated to have caused a change in mean process level.For three of the four models investigated, data should be collected so that the post-intervention record is substantially longer than the pre-intervention record. This is in conflict with the intuitive approach, which would be to collect equal amounts of data before and after the intervention. The threshold (minimum) level of change that can be detected is quite high unless sample sizes of at least 50 and preferably 100 are available; this minimum level is dependent on the complexity of the model required to describe the response of the process mean to the intervention. More complex models tend to require larger sample sizes for the same threshold detectable change level.Uniformity of sampling frequency is a key consideration. Environmental data collection programs have not historically been oriented toward data analysis using time series techniques, thus eliminating a potentially powerful tool from use in many environmental assessment applications.     

CENTER PIVOT IRRIGATION IN THE COLUMBIA BASIN OF WASHINGTON AND OREGON: DYNAMICS AND IMPLICATIONS1

ABSTRACT: As of 1976 over 225,000 acres were being irrigated by center pivot units in a five-county area of the Columbia Basin in Oregon and Washington. Most of the development took place since 1970. Dynamic application of center pivot technology altered the concept of irrigability in the study area, converting lands that were often rolling, sandy, and plagued by wind erosion from low grade grazing to productive irrigated units. This development was entirely by private enterprise, with large corporate farms accounting for much of the effort. Little prior comprehensive planning or coordination took place. When the circulation of water is altered on such a massive scale, however, unplanned impacts may be far reaching. In this case they include:1) acceleration of the shift to high cost thermoelectric generation, 2) alteration of state institutions designed to allocate water, and 3) possible significant alterations of the socioeconomic fabric of small rural service centers.     

Targeted sampling protocol as prelude to bacterial source tracking with Enterococcus faecalis

Recent studies suggest that host origin databases for bacterial source tracking (BST) must contain a large number of isolates because bacterial subspecies change with geography and time. A new targeted sampling protocol was developed as a prelude to BST to minimize these changes. The research was conducted on the Sapelo River, a tidal river on the Georgia coast. A general sampling of the river showed fecal enterococcal numbers ranging from <10 (below the limit of detection) to 990 colony-forming units (CFU) per 100 mL. Locations with high enterococcal numbers were combined with local knowledge to determine targeted sampling sites. Fecal enterococcal numbers around one site ranged from <10 to 24,000 CFU per 100 mL. Bacterial source tracking was conducted to determine if a wastewater treatment facility at the site was responsible for this contamination. The fecal indicator bacterium was Enterococcus faecalis. Ribotyping, automated with a RiboPrinter (DuPont Qualicon, Wilmington, DE), was the BST method. Thirty-seven ribotypes were observed among 83 Ent. faecalis isolates obtained from the Sapelo River and the wastewater lagoon. Sixteen ribotypes were associated with either the river or the lagoon, and only five ribotypes (14%) were shared. Nevertheless, these five ribotypes represented 39 of the 83 Ent. faecalis isolates, almost a majority (47%). These results suggest that the fecal contamination in the river came from the wastewater treatment facility. As a prelude to BST, targeted sampling minimized subspecies changes with geography and time, and eliminated the need for a permanent host origin database by restricting BST to a small geographic area and requiring sampling to be completed in one day.     

Spatial variability of soil carbon in forested and cultivated sites: implications for change detection

The potential to sequester atmospheric carbon in agricultural and forest soils to offset greenhouse gas emissions has generated interest in measuring changes in soil carbon resulting from changes in land management. However, inherent spatial variability of soil carbon limits the precision of measurement of changes in soil carbon and hence, the ability to detect changes. We analyzed variability of soil carbon by intensively sampling sites under different land management as a step toward developing efficient soil sampling designs. Sites were tilled cropland and a mixed deciduous forest in Tennessee, and old-growth and second-growth coniferous forest in western Washington, USA. Six soil cores within each of three microplots were taken as an initial sample and an additional six cores were taken to simulate resampling. Soil C variability was greater in Washington than in Tennessee, and greater in less disturbed than in more disturbed sites. Using this protocol, our data suggest that differences on the order of 2.0 Mg C ha(-1) could be detected by collection and analysis of cores from at least five (tilled) or two (forest) microplots in Tennessee. More spatial variability in the forested sites in Washington increased the minimum detectable difference, but these systems, consisting of low C content sandy soil with irregularly distributed pockets of organic C in buried logs, are likely to rank among the most spatially heterogeneous of systems. Our results clearly indicate that consistent intramicroplot differences at all sites will enable detection of much more modest changes if the same microplots are resampled.     

Commercialization of Dredged-Material Decontamination Technologies

This article describe a unique federal project aimed at the commercialization of different technologies for the decontamination of dredged material. The project is organized so that commercialization is achieved in a seamless way, starting with validation at the bench- and pilot-scale levels, and ending with the actual construction of operational facilities. This is the first integrated sediment decontamination program in which a step-wise bench-scale validation process of innovative/emerging technologies will scale-up to a production-scale facility capable of processing up to 375,000 m³ of dredged material per year. The need to develop public-private partnerships for the facility construction is emphasized as a way of obtaining adequate finding for capital and operating costs during the startup time of the commercialization process. It is expected that the end result of the project work will be the creation of economically-viable, self-sustaining decontamination technology companies.     

A STATISTICAL APPROACH TO ASSESS FACTORS AFFECTING WATER CHEMISTRY USING MONITORING DATA1

ABSTRACT: A method to partition the variation in concentrations of water chemistry parameters in a river is described. The approach consists of fitting a family of curves for each chemical parameter. Each curve indicates the response of the parameter to river flow for a particular time period or location. An analysis of covariance is then used to identify statistically significant differences between curves. Such differences result largely from two factors: (1) the discharge of effluents and (2) river flow-concentration relationships. The deviations from the fitted curves indicate month-to-month variations unrelated to river flow that are controlled by factors such as temperature-related seasonal patterns. Underlying statistical assumptions are discussed with respect to water chemistry data. The technique is applied to a data set consisting of monthly samples of 22 water chemistry parameters from the Sulphur River of Texas and Arkansas. Several patterns of response to river flow and to two effluent discharges were revealed.