Fate and transport

M. W. Kemblowski and co-workers, "Fate and Transport of Residual Hydrocarbon in Ground Water A Case Study," Petroleum Hydrocarbons and Organic Chemicals in Ground Water Prevention, Detection, and Restoration, presented at the conference and exposition. National Water Well Association and American Petroleum Institute, Nov. 17—19, 1987. 

Within recent years there have been a number of review articles regarding the release, fate, and transport of zinc in our environment. The pubHcations have provided the insight not only to the environmental hazards of zinc but also to the biological importance of this essential element as weH (81—85). 

We begin by reviewing the regulatory driving force in the United States for air pollution abatement. To appreciate the objectives of our Federal air pollution control regulations, an understanding of the fate and transport mechanisms in the environment is important. Hence, some general discussions on the behavior of pollutants in the atmosphere are included in this chapter. 

EPA, 1996, is the third edition of EML/DVIES on CD-ROM for distributing exposure models, documentation, and the IMES about many computer models used for exposure assessment and other fate and transport studies as developed by the EPA s Office of Research and Development (ORD). 

Uncertainty on tlie other hand, represents lack of knowledge about factors such as adverse effects or contaminant levels which may be reduced with additional study. Generally, risk assessments carry several categories of uncertainly, and each merits consideration. Measurement micertainty refers to tlie usual eiTor tliat accompanies scientific measurements—standard statistical teclmiques can often be used to express measurement micertainty. A substantial aniomit of uncertainty is often inlierent in enviromiiental sampling, and assessments should address tliese micertainties. There are likewise uncertainties associated with tlie use of scientific models, e.g., dose-response models, and models of environmental fate and transport. Evaluation of model uncertainty would consider tlie scientific basis for the model and available empirical validation. 

Caruso BS, Cox LTJ, Runkel RE, Velleux ML, Bencala KE, Nordstrom DK, Julien PY, Butler BA, Alpers CN, Marion A, Smith KS (2008) Metals fate and transport modelling in streams and watersheds state of the science and SEPA workshop review. Hydrol Process 22 4011... 

The toxicological or cumulative effect of illicit drugs on the ecosystems has not been studied yet. Moreover, their fate and transport in the environment is to a big extent still unknown. Due to their physical-chemical properties (octanol-water partition coefficient, solubility, etc.) some of them, such as cannabinoids, are likely to bioaccumulate in organisms or concentrate in sediments whereas the rest, much more polar compounds, will tend to stay in aqueous environmental matrices. However, continuous exposure of aquatic organisms to low aquatic concentrations of these substances, some of them still biologically active (e.g., cocaine (CO), morphine (MOR) and MDMA) may cause undesirable effects on the biota. 

DoustGD, Huang J-C. 1992. The fate and transport of hazardous chemicals in the subsurface environment. Water Sci Technol 25 169-176. 

USEPA] US Enviromnental Protection Agency. 1997. Mercury Study Report to Congress. Fate and Transport of Mercury in the Environment, Vol. 111. EPA-452/R-97-005, US Enviromnental Protection Agency, US Government Printing Office, Washington, D.C. 

While these objectives for method sensitivity may seem ambitious, experience has shown that data from such studies are much more usable for supporting fate and transport models (development and/or validation efforts) that may have to be used when more precise and geographically detailed probabilistic risk assessments become necessary. 

Litaor MI, Barth GR, Zika EM. 1996. Fate and transport of plutonium-239+240 and americium-241 in the soil of Rocky Flats, Colorado. J Environ Qual 25 671-683. 

Mineral Oil Hydraulic Fluids and Polyalphaolefin Hydraulic Fluids. Limited information about environmentally important physical and chemical properties is available for the mineral oil and water-in-oil emulsion hydraulic fluid products and components is presented in Tables 3-4, 3-5, and 3-7. Much of the available trade literature emphasizes properties desirable for the commercial end uses of the products as hydraulic fluids rather than the physical constants most useful in fate and transport analysis. Since the products are typically mixtures, the chief value of the trade literature is to identify specific chemical components, generally various petroleum hydrocarbons. Additional information on the properties of the various mineral oil formulations would make it easier to distinguish the toxicity and environmental effects and to trace the site contaminant s fate based on levels of distinguishing components. Improved information is especially needed on additives, some of which may be of more environmental and public health concern than the hydrocarbons that comprise the bulk of the mineral oil hydraulic fluids by weight. For the polyalphaolefin hydraulic fluids, basic physical and chemical properties related to assessing environmental fate and exposure risks are essentially unknown. Additional information for these types of hydraulic fluids is clearly needed. 

Ecologically, copper is a trace element essential to many plants and animals. However, high levels of copper in soil can be directly toxic to certain soil microorganisms and can disrupt important microbial processes in soil, such as nitrogen and phosphorus cycling. Copper is typically found in the environment as a solid metal in soils and soil sediment in surface water. There is no evidence that biotransformation processes have a significant bearing on the fate and transport of copper in water. 

Schnoor, J.L., Environmental Modeling—Fate and Transport of Pollutants in Water, Air, and Soil, John Wiley Sons, New York, 1996. 

Wilson, J.T., Fate and transport of MTBE and other gasoline components, in MTBE Remediation Handbook, Moyer, E.E. and Kostecki, P.T., Eds, Amherst Scientific Publishers, Amherst, MA, 2003. 

Crockett, A.B. Hern, S.C. Kinney, W.L. Flatman, G.T. "Guidelines for Field Testing Aquatic Fate and Transport Models Interim Report" U.S. Environ. Prot. Agency, Environ. Monitoring Systems Lab. Las Vegas, Nevada, 1982 p. 174 + Appendices. 

The goal of this paper Is to present the current status of model validation and field testing of chemical fate and transport models other papers in this symposium discuss the state-of-the-art of modeling specific processes, environments, and multimedia problems. The process of model validation, and its various components, is described considerations in field testing, where model results are compared to field observations, are discussedp an assessment of the current extent of field testing for various processes and media is presented and future field testing and data needs are enumerated. 

In the past few years a variety of workshops and symposia have been held on the subjects of model verification, field validation, field testing, etc. of mathematical models for the fate and transport of chemicals in various environmental media. Following a decade of extensive model development in this area, the emphasis has clearly shifted to answering the questions "How good are these models ", "How well do they represent natural systems ", and "Can they be used for management and regulatory decision-making "... 

For an aquatic model of chemical fate and transport, the input loadings associated with both point and nonpoint sources must be considered. Point loads from industrial or municipal discharges can show significant daily, weekly, or seasonal fluctuations. Nonpoint loads determined either from data or nonpoint loading models are so highly variable that significant errors are likely. In all these cases, errors in input to a model (in conjunction with output errors, discussed below) must be considered in order to provide a valid assessment of model capabilities through the validation process. 

Comparisons between observed data and model predictions must be made on a consistent basis, i.e., apples with apples and oranges with oranges. Since models provide a continuous timeseries, any type of statistic can be produced such as daily maximums, minimums, averages, medians, etc. However, observed data are usually collected on infrequent intervals so only certain statistics can be reliably estimated. Validation of aquatic chemical fate and transport models is often performed by comparing both simulated and observed concentration values and total chemical loadings obtained from multiplying the flow and the concentration values. Whereas the model supplies flow and concentration values in each time step, the calculated observed loads are usually based on values interpolated between actual flow and sample measurements. The frequency of sample collection will affect the validity of the resulting calculated load. Thus, the model user needs to be aware of how observed chemical loads are calculated in order to assess the veracity of the values. 

Specific research investigations into sediment/particulate transport, sediment/water/contaminant interactions, soil (unsaturated and saturated) contaminant fate and transport, and biological degradation processes were identified as priorities by the Exposure Assessment workshops. 

Environmental Fate and Transport at the Terrestrial-Atmospheric Interface... 

Pesticide) Pyrethroids European continent Soil and water - Total pesticide use - Spatial distribution of crops - Crop types (cereal, maize, oilseeds, citrus, etc.) - Runoff and soil moisture - Fate and transport parameters [52]... 

Fig. 2 Main processes and factors affecting the fate and transport of chemicals in the environment...

In order to achieve that an environmental fate model is successfully applied in a screening level risk assessment and ultimately incorporated into the decisionmaking tools, the model should have computational efficiency and modest data input. Moreover, the model should incorporate all relevant compartments and all sources of contamination and should consider the most important mechanisms of fate and transport. Although spatial models describe the environment more accurately, such models are difficult to apply because they require a large amount of input data (e.g., detailed terrain parameters, meteorological data, turbulence characteristics and other related parameters). Therefore, MCMs are more practical, especially for long-term environmental impact evaluation, because of their modest data requirements and relatively simple yet comprehensive model structure. In addition, MCMs are also widely used for the comparative risk assessment of new and existing chemicals [28-33]. 

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