CONSTRUCTION WORK FORCE CHARACTERISTICS AND COMMUNITY SERVICE IMPACT ASSESSMENT1

ABSTRACT: Findings of a national survey of the Corps of Engineers construction work force are presented. The purpose of the survey was to obtain information about the construction work force for use in estimating the demand on local community services associated with building Corps projects. Information on numbers of workers and dependents in-migrating to construction sites, the residential location preferences and commuting patterns of this group, and the intentions of this group to remain in local areas after project construction is presented in this paper. An example showing how this information can be used in a community service impact assessment is provided.     

EFFECTIVENESS OF DUPONT TYPAR SHEETING IN CONTROLLING MACROPHYTE REGROWTH AFTER OVERWINTER DRAWDOWN1

ABSTRACT: A new polypropylene sheeting compound, DuPont Typar 3201 and 3301, was applied to the sediments of Country Lake (Portage Co., Ohio) in March 1978 after an overwinter drawdown, and regrowth of rooted macrophytes was compared to an adjacent control area in summer 1978. Regrowth was slight, and macrophyte biomass was at least 100X less than in controls. The sheeting material was permeable to gases and did not “balloon.” This material is recommended for use around docks, swimming areas, and boat mooring sites. Cost in 1978 was about $0.24/m².     

A Complex Systems Model Approach to Quantified Mineral Resource Appraisal

For federal and state land management agencies, mineral resource appraisal has evolved from value-based to outcome-based procedures wherein the consequences of resource development are compared with those of other management options. Complex systems modeling is proposed as a general framework in which to build models that can evaluate outcomes. Three frequently used methods of mineral resource appraisal (subjective probabilistic estimates, weights of evidence modeling, and fuzzy logic modeling) are discussed to obtain insight into methods of incorporating complexity into mineral resource appraisal models. Fuzzy logic and weights of evidence are most easily utilized in complex systems models. A fundamental product of new appraisals is the production of reusable, accessible databases and methodologies so that appraisals can easily be repeated with new or refined data. The data are representations of complex systems and must be so regarded if all of their information content is to be utilized.The proposed generalized model framework is applicable to mineral assessment and other geoscience problems. We begin with a (fuzzy) cognitive map using (+1,0,–1) values for the links and evaluate the map for various scenarios to obtain a ranking of the importance of various links. Fieldwork and modeling studies identify important links and help identify unanticipated links. Next, the links are given membership functions in accordance with the data. Finally, processes are associated with the links; ideally, the controlling physical and chemical events and equations are found for each link. After calibration and testing, this complex systems model is used for predictions under various scenarios. Published on line     

GLYPHOSATE, OTHER HERBICIDES, AND TRANSFORMATION PRODUCTS IN MIDWESTERN STREAMS, 20021

ABSTRACT: The use of glyphosate has increased rapidly, and there is limited understanding of its environmental fate. The objective of this study was to document the occurrence of glyphosate and the transformation product aminomethylphosphonic acid (AMPA) in Midwestern streams and to compare their occurrence with that of more commonly measured herbicides such as acetochlor, atrazine, and metolachlor. Water samples were collected at sites on 51 streams in nine Midwestern states in 2002 during three runoff events: after the application of pre-emergence herbicides, after the application of post-emergence herbicides, and during harvest season. All samples were analyzed for glyphosate and 20 other herbicides using gas chromatography/mass spectrometry or high performance liquid chromatography/mass spectrometry. The frequency of glyphosate and AMPA detection, range of concentrations in runoff samples, and ratios of AMPA to glyphosate concentrations did not vary throughout the growing season as substantially as for other herbicides like atrazine, probably because of different seasonal use patterns. Glyphosate was detected at or above 0.1 μg/1 in 35 percent of pre-emergence, 40 percent of post-emergence, and 31 percent of harvest season samples, with a maximum concentration of 8.7 μg/1. AMPA was detected at or above 0.1 μg/1 in 53 percent of pre-emergence, 83 percent of post-emergence, and 73 percent of harvest season samples, with a maximum concentration of 3.6 μg/1. Glyphosate was not detected at a concentration at or above the U.S. Environmental Protection Agency's maximum contamination level (MCL) of 700 μg/1 in any sample. Atrazine was detected at or above 0.1 μg/1 in 94 percent of pre-emergence, 96 percent of post-emergence, and 57 percent of harvest season samples, with a maximum concentration of 55 μg/1. Atrazine was detected at or above its MCL (3 μg/1) in 57 percent of pre-emergence and 33 percent of post-emergence samples.     

Loblolly pine response to wet-weather harvesting on wet flats after 5 years

The timing of forestry operations relative to weather conditions is a consideration in applying Forestry Best Management Practices (BMPs). Harvesting during different seasons can result in degrees of soil disturbance, the distribution of logging debris, and potentially future stand productivity. The purpose of this study is to examine the response of loblolly pine (Pinus taeda L.) stands after wet- and dry-weather harvesting combined with three site preparation treatments. A 20 × 20 meter grid was established in fifteen 20-year-old, 3.3-ha loblolly pine plantations in South Carolina. A census of soil physical disturbance and slash distribution was made after harvesting. Growth was measured on 1/125th-ha plots at ages two and five. Dry-weather harvested (DWH) sites were 91% undisturbed, and 9% compressed. Wet-weather harvested (WWH) sites were 41% undisturbed, and 59% disturbed. WWH sites averaged 9% bare soil, while DWH sites averaged 16% with 1 kg m^-2 less logging residue; primarily in the form of heavy and light slash. At age five, the green-weight biomass of flat-planted DWH and WWH sites were 13.3 and 12.6 kg tree^-1 respectively, and on the bedded DWH and WWH sites were 18.6 and 22.8 kg tree^-1. Wet weather harvesting did not seem to adversely affect stand growth, and may have improved it. Due to a prolonged drought, bedding had a larger effect on WWH sites than DWH harvested sites. The effects of droughty conditions may be influencing treatment response on these highly productive sites; however, the long-term effects of harvesting on stand growth remain to be seen.     

The Missing Flux in a 35S Budget for the Soils of a Small Polluted Catchment

A combination of cosmogenic and artificial ³⁵S was used to assess the movement of sulfur in a steep Central European catchment affected by spruce die-back. The Jeze?í catchment, Kru?né Hory Mts. (Czech Republic) is characterized by a large disproportion between atmospheric S input and S output via stream discharge, with S output currently exceeding S input three times. A relatively high natural concentration of cosmogenic ³⁵S (42 mBq L^-1) was found in atmospheric deposition into the catchment in winter and spring of 2000. In contrast, stream discharge contained only 2 mBq L^-1. Consequently, more than 95% of the deposited S is cycled or retained within the catchment for more than several months, while older S is exported via surface water. In spring, when the soil temperature is above 0 °C, practically no S from instantaneous rainfall is exported, despite the steepness of the slopes and the relatively short mean residence time of water in the catchment (6.5 months). Sulfur cycling in the soil includes not just adsorption of inorganic sulfate and biological uptake, but also volatilization of S compounds back into the atmosphere. Laboratory incubations of an Orthic Podzol from Jeze?í spiked with 720 kBq of artificial ³⁵S showed a 20% loss of the spike within 18 weeks under summer conditions. Under winter conditions, the ³⁵S loss was insignificant (<5%). This missing S flux was interpreted as volatilized hydrogen sulfide resulting from intermittent dissimilatory bacterial sulfate reduction. The missing S flux is comparable to the estimated uncertainty in many catchment S mass balances (±10%), or even larger, and should be considered in constructing these mass balances. In severely polluted forest catchments, such as Jeze?í, sulfur loss to volatilization may exceed 13 kg ha^-1 a^-1, which is more than the current total atmospheric S input in large parts of North America and Europe.     

Molecular-level investigation of monoaromatic compound sorption to suspended soil particles by deuterium nuclear magnetic resonance

Molecular-level sorption behavior of monoaromatic compounds in suspensions of water-dispersable clay components was studied by measuring 2H nuclear magnetic resonance (NMR) spin-spin relaxation times (T2). In general, decreased T2 values indicate stronger solute-sorbent interactions and increased sorption of the solute. A decreasing trend for T2 values in the order benzene > fluorobenzene > toluene (-C6D5 moiety) was observed, which was probably caused by the hydrophobic effect. The T2 values for benzene and the -C6D5 moiety of toluene increased with increasing pH, whereas the trend with pH was much weaker and less consistent for fluorobenzene and the methyl group of toluene. Conversely, no clear relationship was found between T2 values and pH for dichloromethane. These contrasting results cannot be explained by the pH-dependent self-assembly and hydrophobicity of humics. Instead, directed specific forces, including hydrogen bonding, cation-pi interactions, and aromatic-aromatic interactions, are proposed between the benzene ring of monoaromatic solutes and soil organic matter (SOM). Substituents of benzene affect these interactions by varying the pi electron density. When the soil fraction was treated with NaOH to remove humic and fulvic acids, T2 values for the different monoaromatic solutes were surprisingly lower compared with those for the untreated soil fraction. This result is probably caused by the increased ratio of solutes adsorbed to "hard" or "glassy" SOM components, which leads to less mobile sorbed solute molecules, after removing NaOH-extractable humics that contain more "soft" or "rubbery" SOM components.     

Herbicides in ground water beneath Nebraska's Management Systems Evaluation Area

Profiles of ground water pesticide concentrations beneath the Nebraska Management Systems Evaluation Area (MSEA) describe the effect of 20 yr of pesticide usage on ground water in the central Platte Valley of Nebraska. During the 6-yr (1991-1996) study, 14 pesticides and their transformation products were detected in 7848 ground water samples from the unconfined water table aquifer. Triazine and acetamide herbicides applied on the site and their transformation products had the highest frequencies of detection. Atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] concentrations decreased with depth and ground water age determined with 3H/3He dating techniques. Assuming equivalent atrazine input during the past 20 yr, the measured average changes in concentration with depth (age) suggest an estimated half-life of >10 yr. Hydrolysis of atrazine and deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to hydroxyatrazine [6-hydroxy-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] appeared to be the major degradation route. Aqueous hydroxyatrazine concentrations are governed by sorption on the saturated sediments. Atrazine was detected in the confined Ogallala aquifer in ultra-trace concentrations (0.003 microg L(-1)); however, the possibility of introduction during reverse circulation drilling of these deep wells cannot be eliminated. In fall 1997 sampling, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] was detected in 57% of the 230 samples. Metolachlor oxanilic acid [(2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl) amino]oxo-acetic acid] was detected in most samples. In ground water profiles, concentrations of metolachlor ethane sulfonic acid [2-[(ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino]-2-oxo-ethanesulfonic acid] exceeded those of deethylatrazine. Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] was detected in <1% of the samples; however, alachlor ethane sulfonic acid [2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonic acid] was present in most samples (63%) and was an indicator of past alachlor use.