Choosing the most effective hazardous waste landfill cover

Determining the appropriate criteria and designs for hazardous waste landfill covers has spawned much discussion within the environmental remediation arena. Very little reliable comparison of various technologies exists. Researchers at Los Alamos National Laboratory studied the relative hydrologic performance of four landfill cover designs—two capillary barrier designs, one modified EPA RCRA design, and one control cover. Monitoring the fate of natural precipitation for nearly four years showed that the covers with barrier layers more effectively reduced deep percolation than the control cover. Although none entirely eliminated deep percolation, the RCRA cover, incorporating a clay hydraulic barrier, most effectively controlled it. The two capillary barriers reduced deep percolation, but significant amounts were still produced. Over 90 percent of all percolation through the covers, and lateral flow within the covers, occurred during February through May each year, primarily as a result of snowmelt, early spring rains, and low evapotranspiration. The study also showed that gravel mulch surface treatments (70- to 80-percent ground cover) reduced runoff and erosion. Despite additional shrubs planted on one, the two plots receiving the gravel mulch treatments exhibited equally enhanced amounts of evapotranspiration.     

CALIBRATING AND VERIFYING THE SSARR MODEL -MISSOURI RIVER WATERSHEDS STUDY1

The Streamflow Synthesis and Reservoir Regulation (SSARR) model was calibrated and verified on the Madison and Gallatin watersheds in the upper Missouri River drainage. The study was performed to determine if the SSARR model could simulate snowmelt-runoff volumes to effect better operation of six multipurpose reservoirs on the Missouri River. Physical watershed characteristics and parameter sensitivity are incorporated into a procedure which expedites model calibration. Criteria are established to facilitate parameter development and to objectively evaluate calibration and verification results. A ratio of simulated to observed snowmelt-runoff volumes of the Madison River averaged 1.00 and 1.02 for calibration (N = 8 years) and verification (N = 6 years) with corresponding standard deviations of 0.08 and 0.13. Gallatin volume ratios averaged 0.99 and 0.95 for calibration (N = 7 years) and verification (N = 5 years) with respective standard deviations of 0.08 and 0.28.     

Phenotypic plasticity and “cultural transmission” of alternative social organizations in the fire ant Solenopsis invicta

Summary We investigated the process of sexual maturation in winged queens of the fire ant Solenopsis invicta, a species with two distinct forms of social organization. We found that queens of the monogynous social form (single reproductive queen per colony) differ little or not at all from queens of the polygynous form (multiple reproductive queens per colony) in weight and fat content when these are pupae or newly-eclosed adults. Furthermore, the size of a sclerotized region of the adult thorax, which is set during larval growth, does not differ between queens of the two forms. In contrast, winged queens of the two social forms differ dramatically in their physiological phenotypes once they have matured, with monogynous queens weighing more and having greater fat reserves than polygynous queens. A crossfostering experiment revealed that the different maturation processes of queens of the two forms are induced largely by the type of colony in which a queen matures (monogynous or polygynous) rather than being due to intrinsic genetic differences between the forms. However, genetic variation at a single locus does appear to play some role in determining physiological phenotype in queens of the polygynous form, providing an example of genotype-environment interaction in the expression of these physiological traits. Differences between the social forms in the mature phenotypes that are produced constrain the reproductive options of queens, so that the characteristic social organization of a colony is perpetuated by virtue of the social environment in which new queens are reared. Correspondence to: L. Keller     

Homing behavior of wood thrushes (Hylocichla mustelina)

Summary Using the wood thrush (Hylocichla mustelina) as an example of a typical nocturnal migrant, we employed radio telemetry to follow breeding birds during the course of homing movements following displacements. Seven thrushes were displaced over distances of 6.5 to 17.3 km in a variety of directions from their nesting territories. The thrushes moved in a series of short flights (mean = 2.1 km) performed primarily at dawn. Consequently, the birds took several days to home from even these relatively short displacements. Thrushes flew under clear and solid overcast skies and even in light rain. The pooled individual flights of the birds were significantly oriented in the homeward direction (Fig. 2). Their orientation relative to home did not improve significantly as they progressed toward the goal. Three of the birds were documented to have returned to their home territories. The detailed tracks of the birds preclude the possibility that they homed by random search.     

Modeling economy-wide climate change impacts on Egypt: A case for an integrated approach

This study looks at the role of biophysical sectors and world markets on an integrated economic assessment of climate change impacts on Egypt. Using the outcome from Global Circulation Models (GCMs) and a global model of world food trade (the Basic Linked System; BLS) — changes in crop yields; crop water demands; water and land resource availability; and world market prices were applied to a dynamic, computable general equilibrium model of Egypt (the Standard National Model of the BLS). Modeling results consistently showed that the net effect of climate change on the macro indicator of per capita GDP was not great — regardless of the level of integration. This outcome was only realized through autonomous economic adjustments which implied significant socio-economic and structural change. Including or excluding certain biophysical sectors and world markets influenced the development path and the nature of the autonomous adjustments. The importance of a particular biophysical sector or of world markets was also dependent upon the specific climate change scenario.     

Greenhouse gas mitigation options in the Forest sector of Russia: National and project level assessments

Greenhouse gas (GHG) mitigation options in the Russian forest sector include: afforestation and reforestation of unforested/degraded land area; enhanced forest productivity; incorporation of nondestructive methods of wood harvesting in the forest industry; establishment of land protective forest stands; increase in stand age of final harvest in the European part of Russia; increased fire control; increased disease and pest control; and preservation of old growth forests in the Russian Far-East, which are presently threatened. Considering the implementation of all of the options presented, the GHG mitigation potential within the forest and agroforestry sectors of Russia is approximately 0.6–0.7 Pg C/yr or one half of the industrial carbon emissions of the United States. The difference between the GHG mitigation potential and the actual level of GHGs mitigated in the Russian forest sector will depend to a great degree on external financing that may be available. One possibility for external financing is through joint implementation (JI). However, under the JI process, each project will be evaluated by considering a number of criteria including also the difference between the carbon emissions or sequestration for the baseline (or reference) and the project case, the permanence of the project, and leakage. Consequently, a project level assessment must appreciate the near-term constraints that will face practitioners who attempt to realize the GHG mitigation potential in the forest and agroforestry sectors of their countries.

     

Pollutant monitoring in the Olympic National Park Biosphere Reserve

Interest in global contamination has been instrumental in the establishment of over 33 Biosphere Reserves in the United States. These reserves include pristine areas that have been protected from industrial development. They serve as areas in which present and future environmental pollution can be assessed.Pollutant monitoring studies are being conducted in the Olympic National Park Biosphere Reserve by the U.S. Park Service and the U.S. Environmental Protection Agency. Studies are designed to identify levels of trace element and organic contaminants in physical and biological media. Ten remote sites were selected for intensive sampling. These areas were located in the Hoh, Quinault, and Dosewallips River drainages; at Anderson and Grand Pass; near Ozette Lake and, at the northern edge of Blue Glacier. Their proximity to vehicle-traveled roads varied from 3 to 20 kilometers.Samples were taken in air, water, soil, litter and vegetation. Samples will be analyzed for organic and heavy metal contaminants. Airborne particulate size and chemical characterization is being investigated.     

Soil vapor extraction system design: A case study comparing vacuum and pore‐gas velocity cutoff criteria

Soil vapor extraction (SVE) systems are typically designed based on the results of a vadose‐zone pumping test (transient or steady‐state) using a pressure criterion to establish the zone of influence (ZOI). A common problem associated with pressure‐based SVE design is overestimating the ZOI of the extraction well. As a result, design strategies based upon critical pore‐ gas velocity (CPGV) have become more common. Field tests were conducted at the Savannah River Site (SRS) to determine the influence of a vapor extraction well based upon both a pressure and pore‐ gas velocity design criterion. The results from these tests show that an SVE system designed based upon a CPGV is more robust and will have shorter cleanup times due to increased flow throughout the treatment zone. Pressure‐based SVE design may be appropriate in applications where soil gas containment is the primary objective; however, in cases where the capture and removal of contaminated soil gas is the primary objective, CPGV is a better design criterion. © 2006 Wiley Periodicals, Inc.     

Approaches to Evaluate Water Quality Model Parameter Uncertainty for Adaptive TMDL Implementation1

Abstract: The National Research Council recommended Adaptive Total Maximum Daily Load implementation with the recognition that the predictive uncertainty of water quality models can be high. Quantifying predictive uncertainty provides important information for model selection and decision‐making. We review five methods that have been used with water quality models to evaluate model parameter and predictive uncertainty. These methods (1) Regionalized Sensitivity Analysis, (2) Generalized Likelihood Uncertainty Estimation, (3) Bayesian Monte Carlo, (4) Importance Sampling, and (5) Markov Chain Monte Carlo (MCMC) are based on similar concepts; their development over time was facilitated by the increasing availability of fast, cheap computers. Using a Streeter‐Phelps model as an example we show that, applied consistently, these methods give compatible results. Thus, all of these methods can, in principle, provide useful sets of parameter values that can be used to evaluate model predictive uncertainty, though, in practice, some are quickly limited by the “curse of dimensionality” or may have difficulty evaluating irregularly shaped parameter spaces. Adaptive implementation invites model updating, as new data become available reflecting water‐body responses to pollutant load reductions, and a Bayesian approach using MCMC is particularly handy for that task.