Modeling pesticide volatilization from turf

Pesticide volatilization models are typically based on equilibrium partitioning of the chemical into solid, liquid, and gaseous phases in the soil environment. In turf systems direct vaporization from vegetation surfaces is a more likely source, and it is difficult to apply equilibrium methods to plant material due to the uncertainties of solid-liquid-gas partitioning. An alternative approach is to assume that pesticide volatilization is governed by the same processes that affect water evaporation. A model was developed in which evapotranspiration values, as determined by the Penman equation, were adjusted to chemical vaporization using ratios of water and chemical saturated vapor pressures and latent heats of vaporization. The model also assumes first-order degradation of pesticide on turf vegetation over time. The model was tested by comparisons of predictions with measurements of volatilization for eight pesticides measured during 3 to 7 d in 11 field experiments. Measured volatilization fluxes ranged from 0.1 to 22% of applied chemical. Pesticides were divided into two groups based on saturated vapor pressures and organic C partition coefficients. One pesticide was selected from each group to calibrate the model's volatilization constant for the group, and the remaining pesticides were used for model testing. Testing results indicated that the model provides relatively conservative estimates of pesticide volatilization. Predicted mean losses exceeded observations by 20%, and the model explained 67% of the observed variation in volatilization fluxes. The model was most accurate for those chemicals that exhibited the largest volatilization losses.     

The trends of composite environmental indices in Korea

In this paper we construct for the first time an annual Composite Environmental Index from 1986 to 1995 in Korea, which is useful for evaluating the efficiency of environmental policies. Nine types of environmental problems are examined. On average, the composite index has increased annually by 5.3% over the 1986-1995 period, which implies that overall environmental quality has deteriorated gradually during this period. Problems such as the greenhouse effect, loss of biodiversity, natural resource depletion, and ecotoxication led to deterioration of environmental quality in the 1990s.     

Statistical evaluation of geochemical parameter distribution in a ground water system contaminated with petroleum hydrocarbons

A shallow-depth ground water area was investigated to identify the dominant processes governing the distribution of hydrocarbon contaminants and hydrogeochemical parameters. The ground water in the study site has been highly contaminated with petroleum hydrocarbons. A preliminary pump-and-treatment remediation technology was applied for 4 yr at the site. Multivariate analyses were applied to hydrogeochemical data obtained before and after the rainy season. The pump-and-treatment application, indigenous biodegradation, and mixing by precipitation recharge are the major factors or events involved in the distribution of geochemical parameters of the ground water in the study area. Site-specific artificial pavement also played an important role in the evolution of the ground water chemistry. A conventional graphical analysis method (Piper plot) of major ions did not effectively reveal these effects. In this study, we demonstrate the usefulness of multivariate analysis (factor and cluster analyses) using biodegradation indicator parameters, as well as major cations and anions, for the study of the ground water system in the hydrocarbon-contaminated site.     

Enhanced naphthalene solubility in the presence of sodium dodecyl sulfate: effect of critical micelle concentration

Surfactants can increase the solubility of non-polar compounds, and have been applied in areas such as soil washing and treatment of non-aqueous phase liquids (NAPLs). This investigation explored the feasibility of removing vapor phase polycyclic aromatic hydrocarbon (PAH) from gases using an anionic surfactant. The solubility of vapor phase naphthalene was measured herein using gas chromatograph (GC) with a photon ionization detector (PID). The measurement results indicated that surfactant molecules were not favorable to micelle formation when temperatures increased from 25 degrees C to 50 degrees C. Regardless of whether solutions were quiescent or agitated, equilibrium naphthalene apparent solubility increased linearly with surfactant concentrations exceeding critical micelle concentration (CMC). The pH effects on naphthalene apparent solubility were small. Agitation increased naphthalene apparent solubility and lumped mass transfer coefficients. Furthermore, lumped mass transfer coefficients decreased with increasing surfactant concentration owing to increase in interfacial resistance and viscosity and decreased spherical micelle diffusion coefficients. Finally, the net absorption rate increased because the solubilization effects of micelles exceeded the reduction effects of mass transfer coefficient above the CMC. The enhanced naphthalene apparent solubility from the addition of surfactant can be expressed by an enrichment factor (EF). The EF value of naphthalene for the surfactant solution at 0.1 M with agitation at 270 rpm relative to quiescent water could reach 18.6. This work confirms that anionic surfactant can improve the removal efficiency of hydrophobic organic compound (HOC) from the gas phase.     

Concentrations and activity ratios of uranium isotopes in the groundwater of the Okchun Belt in Korea.

Groundwater samples obtained from the Okchun Belt in Korea were separated into particulate and filtered fraction using a 0.45 microm membrane filter and concentrations and activity ratios of uranium isotopes in the fractions were determined by chemical separation and alpha-spectrometric measurements. Most of the uranium isotopes in the groundwater were found in the filtered water. Only less than 1% of the total uranium was detected in the particulate fraction. The concentrations and activity ratios of uranium isotopes in the groundwater measured in this study were variable, depending upon sampling site. Owing to a rapid material exchange between the subterranean hot waters and the rock strata, the concentrations of 238U in the groundwater in the hot spring area were found to be about four times higher than those elsewhere. Because of the alpha-particle recoil effect, the activity ratios of 234U/238U in the groundwater taken at "cold" spring sites were variable within the range 1.20 to 3.58, depending on the residence time of the groundwater. In the hot spring area, the activity ratios of 234U/238U were close to the equilibrium value (1.10 +/- 0.07) due to rapid erosion of the rock strata by the hot spring water.     

Application of life-cycle assessment to type III environmental declarations

The objective of this research is to develop a desirable type III environmental declaration format for the industrial consumer. A total of five different scenarios were chosen for the presentation of life-cycle assessment results in a format that meets the requirements of a type III environmental declaration. Life-cycle assessment of an electronic component was performed for this purpose. Environmentally significant impact categories and input/output items of a product system derived from the life-cycle assessment are presented in this format. Presenting these information concisely in a standardized format would accelerate the communication of environmental aspects of materials and components in a product supply chain. Thus the type III environmental declaration can be a useful instrument for the manufacturing of an ecoproduct.     

Plant Community Composition and Biomass in Gulf Coast Chenier Plain Marshes: Responses to Winter Burning and Structural Marsh Management

Many marshes in the Gulf Coast Chenier Plain, USA, are managed through a combination of fall or winter burning and structural marsh management (i.e., levees and water control structures; hereafter SMM). The goals of winter burning and SMM include improvement of waterfowl and furbearer habitat, maintenance of historic isohaline lines, and creation and maintenance of emergent wetlands. Although management practices are intended to influence the plant community, effects of these practices on primary productivity have not been investigated. Marsh processes, such as vertical accretion and nutrient cycles, which depend on primary productivity may be affected directly or indirectly by winter burning or SMM. We compared Chenier Plain plant community characteristics (species composition and above- and belowground biomass) in experimentally burned and unburned control plots within impounded and unimpounded marshes at 7 months (1996), 19 months (1997), and 31 months (1998) after burning. Burning and SMM did not affect number of plant species or species composition in our experiment. For all three years combined, burned plots had higher live above-ground biomass than did unburned plots. Total above-ground and dead above-ground biomasses were reduced in burned plots for two and three years, respectively, compared to those in unburned control plots. During all three years, belowground biomass was lower in impounded than in unimpounded marshes but did not differ between burn treatments. Our results clearly indicate that current marsh management practices influence marsh primary productivity and may impact other marsh processes, such as vertical accretion, that are dependent on organic matter accumulation and decay.     

MANAGING TAIWAN'S RESERVOIR WATERSHEDS BY THE ZONING APPROACH1

ABSTRACT: For many years, a commonly used strategy for source water protection in Taiwan has been setting up arbitrary, fixed‐width buffer zones near sensitive waters, such as water‐supply reservoirs, and prohibiting any development in their watersheds. However, such regulations are now often viewed as infringing by the government on landowners' property rights, a situation that has led to citizen protests. This paper describes a proposed strategy that is water‐quality based and uses a quantitative zoning approach. A reservoir's watershed is divided into several zones beginning from the normal water line to the divide. Different levels of best management practices (BMPs) are required for controlling runoff pollution in different zones. The layout of the management zones is based on a number of factors such as reservoir classification, water quality conditions, and physical characteristics of the watershed. The goal of promoting such an approach is to try to balance the needs of watershed development and water quality protection. A case study using the Tapu Reservoir Watershed in Northern Taiwan as an example for illustrating the proposed zoning approach is presented.     

METHOD TO IDENTIFY EFFECTWE RIPARIAN BUFFER WIDTHS FOR ATLANTIC SALMON HABITAT PROTECTION1

ABSTRACT: Successful restoration of declining anadromous species is dependent upon effective riparian buffer zone management. Natural resource managers, policy developers and local conservation groups require science‐based information concerning the width at which a given buffer will be effective for its stated purpose. This paper summarizes a method developed in 1999 to determine effective riparian buffer widths for Atlantic salmon habitat protection as part of the Atlantic Salmon Conservation Plan for Seven Maine Rivers. A major assumption of the method is that no two buffers are alike with respect to their effectiveness and that various buffer characteristics dictate the required width for a given level of effectiveness. The method uses a predictive model that generates suggested riparian buffer widths as a function of specific, measurable buffer characteristics (such as slope, soil characteristics, and plant community structure and density) that affect buffer function. The method utilizes a variable‐width, two‐zone approach and specifies land uses that are consistent with desired buffer function within the two zones.     

EFFECT OF WATER QUALITY STANDARDS ON FARM INCOME,RISK, AND NPS POLLUTION1

ABSTRACT: Enforceable standards play a crucial role in the design and implementation of most water quality policies. The impacts of these standards on farm income and nonpoint source (NPS) pollution can provide valuable information to develop economic policies that can improve water quality with minimal loss in income and minimal risk. This study uses an integration of nonlinear programming and a simulation model to assess the impacts of enforceable standards at technology and farm boundary levels. The results indicate that the type of pollutant regulated, enforcement type, and the level of standard had a significant impact on farm income and water quality. Choice of farm boundary standards over technology standards is dependent on the impact of the policy on other NPS pollutants, in addition to the reduction of nitrate and phosphorus pollutants. Enforcing farm boundary standards on nitrates had desirable effects on subsurface and percolate nitrogen and variance in income. Technology standards were uncertain in their effects because of the restriction on the choice of technologies available to farmers. A comparative policy analysis considering incentives, multiple impacts, transaction costs of implementation, and regional consideration is important to an effective policy design.