Aquatic chemistry is becoming both a rewarding and substantial area of inquiry and is drawing many prominent scientists to its fold. Its literature has changed from a compilation of compositional tables to studies of the chemical reactions occurring within the aquatic environments. But more than this is the recognition that human society in part is determining the nature of aquatic systems. Since rivers deliver to the world ocean most of its dissolved and particulate components, the interactions of these two sets of waters determine the vitality of our coastal waters. This significant vol ume provides not only an introduction to the dynamics of aquatic chem istries but also identifies those materials that jeopardize the resources of both the marine and fluvial domains. Its very title provides its emphasis but clearly not its breadth in considering natural processes. The book will be of great value to those environmental scientists who are dedicated to keeping the resources of the hydrosphere renewable. As the size of the world population becomes larger in the near future and as the uses of materials and energy show parallel increases, the rivers and oceans must be considered as a resource to accept some of the wastes of society. The ability of these waters and the sediments below them to accommodate wastes must be assessed continually. The key questions relate to the capacities of aqueous systems to carry one or more pollutants."

Metal pollution in the aquatic environment

Microbial degradation of hydrocarbons in the environment.

Microbial degradation of petroleum hydrocarbons: an environmental perspective.

Dual role of microalgae: Phycoremediation of domestic wastewater and biomass production for sustainable biofuels production

The environmental and microbiological factors that can influence heavy metal toxicity are discussed with a view to understanding the mechanisms of microbial metal tolerance. It is apparent that metal toxicity can be heavily influenced by environmental conditions. Binding of metals to organic materials, precipitation, complexation, and ionic interactions are all important phenomena that must be considered carefully in laboratory and field studies. It is also obvious that microbes possess a range of tolerance mechanisms, most featuring some kind of detoxification. Many of these detoxification mechanisms occur widely in the microbial world and are not only specific to microbes growing in metal-contaminated environments.

Microorganisms and Heavy Metal Toxicity

Prototheca zopfii is an achlorophyllous alga which degrades oil. It has been found to degrade 10 and 40% of a motor oil and crude oil, respectively, when tested under appropriate conditions. Degradation of the crude oil observed in this study compares well with the amount of degradation accomplished by bacteria. P. zopfii was found to degrade a greater percentage of the aromatic hydrocarbons in motor oil than of the saturated hydrocarbons and a greater percentage of saturated hydrocarbons in crude oil than of aromatic hydrocarbons. Resins and asphaltenes were produced during degradation of motor oil, whereas these fractions in crude oil were degraded. P. zopfii did not demonstrate preferential utilization of lower homologues of cycloalkanes and aromatics as has been observed with bacteria.

Degradation of Petroleum by an Alga, Prototheca Zopfii

Methods of examining hydrocarbons to estimate the microbial degradation of petroleum are compared. Gas-liquid chromatography with a mixed hydrocarbon substrate has been shown to be useful in evaluating microbial potential for degradation of a number of hydrocarbons.

Microbial petroleum degradation: use of mixed hydrocarbon substrates

Microorganisms present in Atlantic Ocean sediment samples collected at a depth of 4,940 m were found to be capable of utilizing hydrocarbons under both ambient and in situ pressures. The rate of utilization under in situ pressure (500 atm) and ambient temperature (20 C) was found to be significantly less compared with hydrocarbon utilization examined under conditions of ambient temperature (20 C) and pressure (1 atm).

Deep-sea bacteria: growth and utilization of hydrocarbons at ambient and in situ pressure.

The concentration of mercury in water and sediment and in the oil extracted from water and sediment was determined for samples collected in Colgate Creek, located in Baltimore Harbor of the Chesapeake Bay. The concentration of mercury in the oil was 4,000 times higher than in sediment and 300,000 times higher than in water samples. The mercury-resistant bacterial populations of the samples studied have been shown to degrade oil, suggesting these bacteria to be a significant factor in the degradation of oil in Colgate Creek.

Mercury-resistant bacteria and petroleum degradation.

Bacteria from water and sediment of an oil-polluted harbor were examined for ability to degrade petroleum. Water samples contained a greater variety of bacterial species capable of degrading petroleum than sediment. Cultures from both water and sediment contained Pseudomonas and Acinetobacter spp. Bacteria present in the water samples produced significantly greater degradation of 2-,3-,4-, and 5-ring cycloalkanes and mono-, di-, tri-, tetra-, and pentaaromatics compared with bacteria in sediment samples.

J. D. Walker

Papers

Degradation of Petroleum by an Alga, Prototheca Zopfii

Microbial petroleum degradation: use of mixed hydrocarbon substrates

Deep-sea bacteria: growth and utilization of hydrocarbons at ambient and in situ pressure.

Mercury-resistant bacteria and petroleum degradation.

Evaluation of petroleum-degrading potential of bacteria from water and sediment.