Impact of drying and composting procedures on the concentrations of 4-nonylphenols, di-(2-ethylhexyl)phthalate and polychlorinated biphenyls in anaerobically digested sewage sludge

Enhanced treatments of sewage sludge produce a more manageable product for agricultural use by stabilizing the material, removing water, and reducing the possibility of pathogen transfer. We investigated the impact of pilot-scale composting and drying of sludge on physicochemical characteristics and on the concentrations of some organic contaminants. During the 143 day composting procedure, organic matter fell 22% and moisture by half. Concentrations of 4-nonylphenols (4-NPs) fell by 88% and di-(2-ethylhexyl) phthalate (DEHP) by 60%; losses continued throughout the procedure. Losses of total polychlorinated biphenyls (PCBs) were 11%, mostly from the lower molecular weight congeners, suggesting volatilization as the most likely loss mechanism. The drying process was much shorter, 40 days, yet organic matter content decreased by 27% and moisture by 85%. Losses of 4-NPs (39%) and DEHP (22%) were less than in composting and stopped when moisture content became constant. There were no losses of PCBs. Both treatments are simple, practical procedures that reduce the volume of waste and are applicable in situ on farms. Composting would be the method of choice for reducing organic contaminants but requires much longer times than drying.     

Partitioning of cadmium,copper, lead and zinc amongst above-ground parts of seed and grain crops grown in selected locations in the USA

The distribution of Cd, Cu, Pb and Zn in above-ground parts of corn, small grains and pulse crops was investigated. Sampled parts included grain or seed, leaves, stems, silk and husks of corn-ears, rachilla and chaff of small grains and pods of bean plants. The distribution of these elements was variable and reflected, primarily, their relative mobility between plant parts including transfer into the grain. Generally, Zn and Cu were preferentially transferred into the seed or grain, while Cd and Pb were selectively excluded from these organs. For example, the distribution pattern in ears of corn was: for Cd, husks > silk > grain; for Zn, silk > grain > husks. The selective transfer of Zn and Cu into seed or grain, in contrast to the restricted movement of Cd and Pb into these organs, may be the result of selective absorption of Zn and Cu over Cd and Pb by vascular transfer cells within the plant's reproductive tissues. The effect of soil type on Cd, Cu, Pb and Zn levels in cereal grain or pulse seed was small compared to the differences found in the concentrations of these elements between different plant organs. Thus, grain and seed crops serve as natural barriers to the movement of the potentially toxic heavy metals, Cd and Pb, into the animal/human food chain, minimising their transfer from soils while conserving Zn and Cu levels in edible portions of these crops.Soil Scientist, USDA, Soil Conservation Service, Retired.     

Analysis of organic nitrogen removal in municipal wastewater by reverse osmosis

The results of a pilot study that was conducted to determine the total nitrogen removal by the reverse osmosis process are presented. The organic nitrogen removal rates are compared with removals observed from three full-scale reverse osmosis facilities and four pilot studies. The results of this analysis suggest that organic nitrogen removal is variable and that reverse osmosis may not consistently produce total nitrogen levels less than 1.0 mg/L without additional treatment. Three hypotheses to explain the variability in organic nitrogen removal in the different data sets are presented.     

Threshold to maturity in a long-lived reptile: interactions of age, size, and growth

Thresholds to sexual maturity—either age or size—are critical life history parameters. Usually investigated in short-lived organisms, these thresholds and interactions among age, size, and growth are poorly known for long-lived species. A 34-year study of captive green turtles (Chelonia mydas) that followed individuals from hatching to beyond maturity provided an opportunity to evaluate these parameters in a long-lived species with late maturity. Age and size at maturity are best predicted by linear growth rate and mass growth rate, respectively. At maturity, resource allocation shifts from growth to reproductive output, regardless of nutrient availability or size at maturity. Although captive turtles reach maturity at younger ages than wild turtles, the extensive variation in captive turtles under similar conditions provides important insights into the variation that would exist in wild populations experiencing stochastic conditions. Variation in age/size at maturity should be incorporated into population models for conservation and management planning.     

Effects of controller-pilot communication medium,flight phase and the role in the cockpit on pilots’ workload and situation awareness

This study explores the effects of communication medium, flight phase, and the role in the cockpit on pilots’ workload and situation awareness. Eight pilots with the experience of Controller-Pilot Data Link Communications (CPDLCs) participated in this simulated experiment. Two types of communication medium (voice and datalink), three types of flight phase (departure, cruise, and arrival), and two types of role (pilot flying and pilot non-flying) were investigated in the experiment. The results indicated that flight phase is a significant factor and cruise is the most suitable phase for datalink use on pilots’ acceptance, workload, and situation awareness performance. Both medium and role were not the significant factors. Since there is no significant difference on medium when no extra tasks and interferences involved in a normal flight, that the use of CPDLC can be justified during all phases of a no-event flight. In addition, the results of usability indicated that the simulated CPDLC with command selection functions proposed in this study provides good utility for the participants. In order to use the CPDLC for all phases of flight in the future, adding more command selection functions in place of typing messages by pilots and accommodating appropriate interfaces for different phases are recommended to enhance the usability of the CPDLC unit.     

Circuit-theory applications to connectivity science and conservation

Conservation practitioners have long recognized ecological connectivity as a global priority for preserving biodiversity and ecosystem function. In the early years of conservation science, ecologists extended principles of island biogeography to assess connectivity based on source patch proximity and other metrics derived from binary maps of habitat. From 2006 to 2008, the late Brad McRae introduced circuit theory as an alternative approach to model gene flow and the dispersal or movement routes of organisms. He posited concepts and metrics from electrical circuit theory as a robust way to quantify movement across multiple possible paths in a landscape, not just a single least-cost path or corridor. Circuit theory offers many theoretical, conceptual, and practical linkages to conservation science. We reviewed 459 recent studies citing circuit theory or the open-source software Circuitscape. We focused on applications of circuit theory to the science and practice of connectivity conservation, including topics in landscape and population genetics, movement and dispersal paths of organisms, anthropogenic barriers to connectivity, fire behavior, water flow, and ecosystem services. Circuit theory is likely to have an effect on conservation science and practitioners through improved insights into landscape dynamics, animal movement, and habitat-use studies and through the development of new software tools for data analysis and visualization. The influence of circuit theory on conservation comes from the theoretical basis and elegance of the approach and the powerful collaborations and active user community that have emerged. Circuit theory provides a springboard for ecological understanding and will remain an important conservation tool for researchers and practitioners around the globe.     

COLIFORMS AND WATER QUALITY: USE OF DATA IN PROJECT DESIGN AND OPERATION1

ABSTRACT: Knowledge of coliform transport and disappearance may provide information for project design and operation that minimizes potential water quality problems such as the violation of body contact recreation standards. Storm events were sampled in the Caddo River above DeGray Reservoir, Arkansas, and then tracked through the reservoir using the increased turbidity associated with the storm flows. Fecal coliforms were sampled both in the river and throughout the water column in the reservoir. In general, increased fecal coliform concentrations were closely associated with the increased turbidity resulting from the storm flows. This association existed for all three types of turbidity plume movement - overflow, interflow, and underflow. As the turbidity plume moved down the reservoir, fecal coliform concentrations decreased due to die-off, settling, and dilution. With several assumptions, it is possible to use this information to assist in locating recreational sites in a reservoir or to anticipate possible body contact standard violations at existing recreation sites.     

Lime stabilization and land disposal of cold region wastewater lagoon sludge

Effects of lime [Ca(OH)₂] stabilization upon the pathogenic population in accumulated solids associated with the operation of two aerated wastewater lagoons in Alaska and two facultative wastewater lagoons in northern Utah were evaluated. The subsequent drying, at a temperature of 12 °C, of the lime stabilized sludges on sand and soil beds was also investigated. The lime stabilization of the lagoon sludges was evaluated by dosing the sludges with lime and applying sludges to bench scale drying beds. Lime addition produced high fecal coliform reduction, and the limed sludges readily dewatered on both sand and soil beds.     

Satisfaction with environmental change: An empirical analysis of attitudes toward air quality by recent interstate migrants

How (and whether) people perceive environmental change is a question which economists have generally chosen to finesse rather than explore. The three components of attitudes (cognitive, affective, behavioral) are identified and a “satisfaction” metric is used to evaluate the nonbehavioral components for recent in-migrants to Oregon. An interaction model is used to relate changes in satisfaction to changes in air quality and to personal characteristics of the migrants. In general, a valid cognitive dimension exists; changes in satisfaction are in fact consistent with changes in air quality data.