Fate and effects of pentachlorophenol in hard- and soft-water microcosms

The influence of hard water and soft water on the fate and effects of pentachlorophenol (PCP) was investigated in small microcosms. Minor differences in the fate of PCP and minor changes in microcosm structure were noted between the hard- and soft-water systems. Definite differences between hard-and soft-water systems were detected in dissolved oxygen production and dissolved silica concentration at an exposure concentration of 4 mg 1⁻¹ PCP.     

The Missoula Valley semivolatile and volatile organic compound study: seasonal average concentrations

The city of Missoula is located in a high mountain valley (elevation 3200 ft.) in western Montana and contains one of the largest populations in the entire Rocky Mountain Region completely enclosed by mountains. During the 2000/2001 Missoula Valley Sampling Program, ambient levels of 61 semivolatile organic compounds (SVOCs) and 54 volatile organic compounds (VOCs) were originally quantified before refining the analytical program to 28 of the most prominent SVOCs and VOCs found in the Missoula Valley airshed. These compounds were measured over 24-hr periods at two locations throughout an entire year. This study provides the first, comprehensive appraisal of the levels of SVOCs and VOCs measured simultaneously throughout all four seasons at two locations in the Missoula Valley, including those levels measured during the 2000 Montana wildfire season. Generally, SVOC levels were comparable between both sides of the Missoula Valley. However, there were nearly double the amount of VOCs measured at the more urban Boyd Park site compared with the rural Frenchtown sampling site, a result of the greater number of automobiles on the eastern side of the Valley. SVOCs and VOCs were measured at their highest levels of the sampling program during the winter. Forest fire smoke samples collected during the summer of 2000 showed significant increases in SVOC phenolic compounds, including phenol, 2-methylphenol, 4-methylphenol, and 2,4-dimethylphenol. Although there were modest increases in some of the other SVOCs and VOCs measured during the fire season, none of the increases were as dramatic as the phenolics.     

Effect of a starch-rich industrial wastewater on the acid-phase anaerobic digestion process.

This research investigated the effect of varying the starch-rich, industrial-wastewater component of mixtures with municipal wastewater fed to an anaerobic digester. A laboratory-scale, completely-mixed anaerobic digester was operated at an HRT of 30 h, an SRT of 10 d, and an ambient temperature of 21.5 +/- 1.5 degrees C. The industrial-to-municipal ratios tested were 1:3, 1:1, 3:1, and 100% industrial by volume. Steady-state, acidogenic conditions were achieved for all runs, except 100% industrial. The pH was observed to drop substantially as the industrial constituent of the feed increased. Net volatile fatty acids (VFA) production reached a plateau of approximately 800 mg/L at ratios of 1:1 and higher, while volatile suspended solids (VSS) reduction steadily increased as the industrial component rose. The specific VFA and soluble chemical oxygen demand (SCOD) production rates leveled off at approximately 0.070 mgVFA/ mgVSS.d and 0.124 mgSCOD/mgVSS.d, respectively, for all the mixtures investigated, except for 100% industrial. In this latter case, both rates dropped dramatically. Finally, acetic and propionic acid concentrations fell as the industrial proportion of the mixture increased. This was compensated by a rise in butyric acid production.     

Development of a protocol for monitoring status and trends in forest soil carbon at a national level

The national Forest Health Monitoring (FHM) program requires protocols for monitoring soil carbon contents. In a pilot study, 30 FHM plots loblolly shortleaf (Pinus taeda L./Pinus echinata Mill.) pine forests across Georgia were sampled by horizon and by depth increments. For total soil carbon, approximately 40% of the variance was between plots, 40% between subplots and 20% within subplots. Results by depth differed from those obtained by horizon primarily due to the rapid changes in carbon content from the top to the bottom of the A horizon. Published soil survey information overestimated bulk densities for these forest sites. The measurement of forest floor depths as a substitute to sampling did not provide reliable estimates of forest floor carbon. Precision of replicate samples was approximately 10-30% for field duplicates and 5-10% for laboratory duplicates. Based on national indicator evaluation criteria, sampling by depth using bulk density core samplers has been recommended for national implementation. Additional procedures are needed when sampling organic soils or soils with a high percentage of large rock fragments.     

Land reclamation requirements and their estimated effects on the coal industry

This paper develops a model of the bituminous coal industry that is then used to simulate the price, output, and employment effects of land reclamation requirements in strip mining (other things equal). Our main conclusion is that a requirement to return strip-mined land to its approximate original contour and vegetative cover would have only slight effects on either sector of the industry. We estimate that such a requirement, had it been imposed in 1971, would have decreased strip-mining employment and output by 2.370, while inducing an increase in underground employment more than sufficient to offset these job losses.     

Intertemporal production externalities,technical change,and public expenditure analysis

This paper discusses the implications of relative price change for public expenditure analysis involving natural environments. It develops a model which identifies those demand and supply factors which must be considered in the evaluation of the time stream of benefits associated with the amenity services provided by natural environments in their preserved status.     

Selection of plants for optimization of vegetative filter strips treating runoff from turfgrass

Runoff from turf environments, such as golf courses, is of increasing concern due to the associated chemical contamination of lakes, reservoirs, rivers, and ground water. Pesticide runoff due to fungicides, herbicides, and insecticides used to maintain golf courses in acceptable playing condition is a particular concern. One possible approach to mitigate such contamination is through the implementation of effective vegetative filter strips (VFS) on golf courses and other recreational turf environments. The objective of the current study was to screen ten aesthetically acceptable plant species for their ability to remove four commonly-used and degradable pesticides: chlorpyrifos (CP), chlorothalonil (CT), pendimethalin (PE), and propiconazole (PR) from soil in a greenhouse setting, thus providing invaluable information as to the species composition that would be most efficacious for use in VFS surrounding turf environments. Our results revealed that blue flag iris (Iris versicolor) (76% CP, 94% CT, 48% PE, and 33% PR were lost from soil after 3 mo of plant growth), eastern gama grass (Tripsacum dactyloides) (47% CP, 95% CT, 17% PE, and 22% PR were lost from soil after 3 mo of plant growth), and big blue stem (Andropogon gerardii) (52% CP, 91% CT, 19% PE, and 30% PR were lost from soil after 3 mo of plant growth) were excellent candidates for the optimization of VFS as buffer zones abutting turf environments. Blue flag iris was most effective at removing selected pesticides from soil and had the highest aesthetic value of the plants tested.     

NEW ZEALAND'S NATIONAL WATER QUALITY MONITORING NETWORK - DESIGN AND FIRST YEAR'S OPERATION1

ABSTRACT: The design and implementation of a national surface water quality monitoring network for New Zealand are described. Some of the lessons learned from the first year of operation are also addressed. Underpinning the design, and specified in advance, are the goal and objectives, the data quality assurance system, and the mechanism for data interpretation and reporting. Because of the difficulties associated with the use of a multitude of different agencies, only one agency is involved in field work and one laboratory undertakes the analysis. Staff training has been given a high priority. The network has been designed to give good trend detectability for regular sampling over a 5–10 year period.     

Assessing Linkages in Stream Habitat,Geomorphic Condition,and Biological Integrity Using a Generalized Regression Neural Network

Watershed managers often use physical geomorphic and habitat assessments in making decisions about the biological integrity of a stream, and to reduce the cost and time for identifying stream stressors and developing mitigation strategies. Such analysis is difficult since the complex linkages between reach‐scale geomorphic and habitat conditions, and biological integrity are not fully understood. We evaluate the effectiveness of a generalized regression neural network (GRNN) to predict biological integrity using physical (i.e., geomorphic and habitat) stream‐reach assessment data. The method is first tested using geomorphic assessments to predict habitat condition for 1,292 stream reaches from the Vermont Agency of Natural Resources. The GRNN methodology outperforms linear regression (69% vs. 40% classified correctly) and improves slightly (70% correct) with additional data on channel evolution. Analysis of a subset of the reaches where physical assessments are used to predict biological integrity shows no significant linear correlation, however the GRNN predicted 48% of the fish health data and 23% of macroinvertebrate health. Although the GRNN is superior to linear regression, these results show linking physical and biological health remains challenging. Reasons for lack of agreement, including spatial and temporal scale differences, are discussed. We show the GRNN to be a data‐driven tool that can assist watershed managers with large quantities of complex, nonlinear data.     

Recommended design for more accurate duplication of natural conditions in salt marsh creation

Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been proposed, with the goal of increasing the area of habitat available to endangered whooping cranes (Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation, and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans. Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created marshes to natural reference sites, potentially improving habitat function.