Wells mercury contamination

This book has identified the most useful indicators of environmental changes in mercury contamination in 4 compartments of the environment 1) airsheds and watersheds, 2) water and sediment, 3) aquatic organisms (with emphasis on freshwater ecosystems), and 4) wildlife that live in freshwater, terrestrial, and/or coastal ecosystems. The indicators identified in this book are wide-ranging and involve measurements made at several different scales of time and space. The authors believe that these indicators will provide the best information to policymakers, as well as other stakeholders, as to whether environmental concentrations are changing (A indicators) and what the reasons for those changes might be (B indicators). 

The assembly of functionalized nanostructured silica with uniform pore channels using neutral alkylamine surfactants (S°I° -> HMS) and non-ionic alkylpolyethyleneoxide surfactants (N°I° —> MSU-X) provides many advantages over conventional electrostatic assembly pathways (S+f, etc.). In contrast with electrostatically assembled MCM-41-type materials, mesostructured adsorbents produced by non-electrostatic assembly methods typically possess pore channel structures and particle morphologies which improve their ability to interact with targeted adsorbate species. Moreover, non-electrostatic assembly pathways are well-suited for the direct synthesis of functionalized mesostructured silica by one-step preparation processes under ambient temperature, neutral pH conditions. The environmental application of such materials for the treatment of mercury-contaminated water is also demonstrated. 

Case studies will be presented, essentially from an extensively studied system (the Ria de Aveiro coastal lagoon, west coast of Portugal), where a well-defined anthropogenic mercury contamination gradient has justified numerous studies on the bioaccumulation of contaminants and its effects. 

Reducing or eliminating anthropogenic mercury releases will require the control of releases from mercury-contaminated raw materials and feedstocks, as well as reducing or eliminating the use of mercury in products and processes. 

ABSTRACT The dangers of mercury and its derivatives, especially organomercury compounds have been well dociunented for almost half a century. Concerns remain regarding mercury contamination in aqueous ecosystems. Significant quantities of mercury are present in fossil fuels, particularly petrochemicals. 

The dangers of mercury (Hg) and its derivatives, especially organomercury compounds, have been well documented for almost half a century. Significant concerns remain regarding mercury contamination in aqueous ecosystems. The US EPA has advanced water quality criteria [1] for the protection of organisms native to water environments. The criterion for mercury in fi esh water ecosystems is 12 nanogram/liter (ng/1), and the mercury chronic criterion for salt water is 25 ng/1. These extremely low criteria present significant demands for the analyst, and atomic fluorescence spectroscopy provides a viable option for the measurements. 

Mercury-tolerant strains of bacteria and protozoa have been reported. Mercury-resistant strains of bacteria are common. In Chesapeake Bay, for example, at least 364 strains of bacteria that were isolated were resistant to HgCb. Most were pseudomonads, and almost all were from seven genera. Other groups of bacteria known to materially influence mercury fluxes in saline waters include strains of Escherichia coli that convert Hg + to Hg, and strains of anaerobic methanogenic bacteria that enhance the transfer of methylcobalamin to Hg + under mild reducing conditions. Some mercury-resistant strains were reported to degrade petroleum as well. Mercury-resistant strains of bacteria have been recommended as bioindicators of environmental mercury contamination and as markers of methylmercury in biological samples. The mercury-resistant... 

It has been well-documented that fossil fuel canbustion is a source of mercury contamination. The mercury content of thirty-six American coals ranged from about 70 ppb to as much as 33,000 ppb (Joensuu, 1971). Studies conducted by Gladney and Gordon (1978) indicate that as much as 93 percent of the total mercury liberated from a coal-fired power plant was concentrated in the < 2 pm particulate size fraction. Mercury data for oil is limited although crude oil samples from California contained frcmi 1,900 to 21,000 ppb mercury (Bailey, et al., 1961). 

The most often used subphase is water. Mercury and otlier liquids [12], such as glycerol, have also occasionally been used [13,14]. The water has to be of ultrapure quality. The pH value of tire subphase has to be adjusted and must be controlled, as well as tire ion concentration. Different amphiphiles are differently sensitive to tliese parameters. In general it takes some time until tire whole system is in equilibrium and tire final values of pressure and otlier variables are reached. Organic contaminants cannot always be removed completely. Such contaminants, as well as ions, can have a hannful influence on tire film preparation. In general, all chemicals and materials used in tire film preparation have to be extremely pure and clean. 

Direct reading samplers include simple devices such as colorimetric indicating tubes in which a color change indicates the presence of the contaminant in air passed through the tube, or instruments which are more or less specific for a particular substance. In the latter category are carbon monoxide indicators, combustible gas indicators (explosimeters) and mercury vapor meters, as well as a number of other instruments. 

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