No description available.

Digitized by Kansas Correctional Industries

Anthropocene is the current era in which human activities modify various environmental properties, which have implications for many coastal processes. Anthropogenic stressors increasingly affect coasts and push these environments to a new altered equilibrium state. However, monitoring such pollution is a challenging task because coastal systems are highly dynamic and integrate the physicochemical forces at work on freshwater bodies, estuaries and lagoons with the oceanographic characteristics of adjacent seas. The current thesis addresses pollution of coastal environments in a broad way, with special attention to the current and historic problematic of estuarine contamination by metals. Firstly, it introduces the chemical (e.g. metals, persistent organic pollutants, and emerging contaminants), physical (e.g. microplastics, sediment loads, temperature), and biological (e.g. microbiological contamination, invasive species) pervasive anthropogenic influence in coastal areas. This introductory chapter is followed by a discussion on the limitations towards holistic environmental health assessments that are imposed by the scarcity of tools and multidisciplinary approaches. At that juncture, we perform a deep investigation of metal fate and its effects in estuaries. The review of the scientific literature in the third chapter provides a transdisciplinary conceptual framework for the estuarine behaviour of metals and its impacts on fauna and flora. This comprehensive overview and conceptual model are further accompanied by an elaboration on empirical models, as well as discussion of data on metal behaviour under laboratory and field conditions. While our review postulates that most studies had observed a non-conservative behaviour of metals in estuaries, our data suggests that at local scale such phenomenon is greatly explained by a high metal mobilisation driven by biogeochemical gradients. In fact, our results demonstrate that iron mobilisation regulates the pollution levels of iron and potentially other metals in an intertidal area under strong anthropogenic influence. In summary, estuarine physicochemical gradients, biogeochemical processes, and organism physiology are jointly coordinating the fate and potential effects of metals in estuaries, and both realistic model approaches and attempts to postulate site-specific water quality criteria or water/sediment standards must consider such interactions.

none

Thesis (Ph.D.)--Brown University, 2008. / Vita. Advisor : Karl Jacoby. Includes bibliographical references (leaves 322-343).

Thesis (M.Sc.)--University of Adelaide, Dept. of Zoology, 1980.

Univ., Diss.--Lund, 1998.

Thesis (M.P.A.)--University of Alabama at Birmingham, 2007. / Description based on contents viewed June 26, 2007; title from title screen. Includes bibliographical references (p. 177-191).

The longterm fate of petroleum in four marine environments was Investigated: The fate of petroleum on the surface of the ocean was elucidated by undertaking a detailed study of petroleum residues polluting the Pacific Ocean. First, the extent of contamination of the Pacific by petroleum residues was assessed by measuring the amounts of tar in 2092 neuston tows over a nine-year period (1967-1975). The South Pacific was found to be free of tar; the Northeast Pacific was slightly polluted, with an average of 0.03 mg/m² . The Northwest Pacific, particularly the Kuroshio current system, was the most severely polluted area: all 55 tows between 25° and 40°N in the Northwest Pacific were contaminated. The average concentration in that area 2 was 2.1 mg/m² , representing a standing stock of about 25,000 metric tons of tar. Chemical analyses of the tar as well as its distribution pattern strongly imply that it originates primarily from tanker traffic, and from tanker sludge in particular. The pollutants appear to be discharged by tanker on the very large Middle East to Japan tanker route, then become entrained in the Kuroshio current and create a plume of contamination which extends downstream for 7000 kilometers across the Pacific. Initially evaporation is the most important weathering mechanism acting on the tar, removing component up to the volatility of pentadecane over a period of days or perhaps weeks. Thereafter, microbial degradation is dominant, probably acting for over a year on many particles. Both of these processes increase the density of the residues, and this effect, combined with the overburden of fouling growth that develops, eventually results in the slow sinking of the tar into the depths of the ocean. The fate of petroleum in the intertidal environment was studied by following the natural degradation of the oil after a small (200 ton) oil spill of #5 fuel oil. The most important weathering process was microbial degradation. Evaporation played only a minor role, while photo-oxidation and dissolution had no apparent effect. The microbal attack took approximately one year to complete the degradation of the n-paraffin fraction of the spilled oil, leaving a thin asphaltic residue on the beach. The combined effect of microbial degradation and abrasive weathering removed roughly 95% of the oil from the beach over the period of a year. The fate of oil in the benthic environment was studied by treating 500 ml quantities of crude oil with a commercial sinkant, then placing the oil on soft sediments in about 6 meters of water. Again in the benthic environment, microbial action was the process responsible for the degradation of the oil. Evaporation had no opportunity to act, dissolution was ineffective, and photo-oxidation did not occur because of the low energy and intensity of the light reaching the sediment. The benthic petroleum samples were slow to degrade: the oil remained unchanged in chemical composition for at least 6 months, and after 16 months the n-paraffins were only partly degraded. Oil dissolved in the water column was investigated by adding a spike of #2 fuel oil to an enclosed column of water 2 m in diameter by 15 m deep, and monitoring its fate by fluorescence spectroscopy. For water a meter or two in depth, exchange with the atmosphere played the dominant role in removing the hydrocarbons from the water column, but at 7 m and below, microbial degradation and sedimentation were the more important processes. The disappearance of the oil approximately followed an exponential decay curve. The half life for a large dissolved oil spike was about 3 days (less for a smaller spike) so that 95% removal occurred within 2 weeks. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in ful llment of the requirements for the degree of Master of Science. March 27, 2013 / The transport of chemicals through soils to the groundwater or precipitation at the soils surfaces leads to degradation of the resources such as soil fertility, drinking water and so on. Serious consequences may be su ered in the long run. In this dissertation, we consider macroscopic deterministic models de- scribing contaminant transport in saturated soils under uniform radial water ow backgrounds. The arising convection-dispersion equation given in terms of the stream functions is analyzed using classical Lie point symmetries. A number of exotic Lie point symmetries are admitted. Group invariant solu- tions are classi ed according to the elements of the one-dimensional optimal systems. We analyze the group invariant solutions which satisfy some physical boundary conditions. The governing equation describing movements of contaminants under ra- dial water ow background may be given in conserved form. As such, the conserved form of the governing equation may be written as a system of rst order partial di erential equation referred to as an auxiliary system, by an in- troduction of the nonlocal variable. The resulting system of equations admits a number of (local) point symmetries which induce the nonlocal symmetries for the original governing equation. We construct classes of solutions using the admitted genuine nonlocal symmetries, which include the invariant solutions obtained via corresponding point symmetries of the governing equation.