Mercury groundwater

Krabbenhoft DP, Babiarz CL. 1992. The role of groundwater transport in aquatic mercury cycling. Water Resources Res 28 3119-3128. 

In landfills, heavy metals have the potential to leach slowly into soil, groundwater, or surface water. Dry cell batteries contribute about 88% of the total mercury and 50% of the cadmium in the MSW stream. In the past, household batteries accounted for nearly half of the mercury used in the United States and over half of the mercury and cadmium in the MSW stream. When burned, some heavy metals such as mercury may vaporize and escape into the air, and cadmium and lead may end up in the ash. 

When the mercury-containing equipment is improperly disposed of on land, the mercury will eventually leachate out from the waste equipment. Once released into the environment, mercury remains there indefinitely, contaminating the soil, sediment, and groundwater. This contamination eventually enters the food chain, exposing local populations to mercury s harmful effects.2... 

Until now there has been no effective technology for reducing groundwater mercury to two parts per billion, as required by the maximum contamination limit for drinking water established by the U.S. Food and Drug Administration and the U.S. EPA. 

A half-life of about 40 days was reported for hexachloroethane in an unconfined sand aquifer (Criddle et al. 1986). Laboratory studies with wastewater microflora cultures and aquifer material provided evidence for microbial reduction of hexachloroethane to tetrachloroethylene under aerobic conditions in this aquifer system (Criddle et al. 1986). In anaerobic groundwater, hexachloroethane reduction to pentachloroethane and tetrachloroethylene was found to occur only when the water was not poisoned with mercury chloride (Roberts et al. 1994). Pentachloroethane reduction to tetrachloroethylene occurred at a similar rate in both poisoned and unpoisoned water. From these results, Roberts et al. (1994) suggested that the reduction of hexachloroethane to tetrachloroethylene occurred via pentachloroethane. The first step, the production of pentachloroethane, was microbially mediated, while the production of tetrachloroethylene from pentachloroethane was an abiotic process. 

ISOTRON Corporation s electrokinetic decontamination process is a patented, in situ process for the removal of contaminants from soil, groundwater, and porous concrete. The technology applies a low-intensity direct current (DC) across electrode pairs to facilitate electromigration and electro-osmosis of contaminants. The process works primarily on highly soluble ionized inorganics including alkah metals, chlorides, nitrates, and phosphates. Heavy metals such as lead, mercury, cadmium, and chromium have also responded favorably. 

The Lewis ENVIRO-CLEAN process removes and recovers metals such as chromium, copper, nickel, mercury, lead, zinc, iron, and cadmium and has effectively demonstrated that it can treat a matrix of multiple metals in a single stream with positive results. The process treats wastes from wood preserving, metal finishing, mining, surface and groundwaters. The two-step process uses granular-activated carbon and electrolytic metal recovery to yield a salable metallic by-product. 

Arsenic boron and mercury. As discussed in the following section, As, B, and Hg are typically enriched in geothermal fluids, as compared to surface- and groundwaters (Sakamoto et al. 1988 Ballantyne Moore 1988). Being quite fugitive, Hg partitions significantly into the steam phase at... 

The distribution of Hg within seepage lakes is a net result of the processes that control Hg transport between the atmosphere, water column, seston, sediments, and groundwater. This discussion focuses on the processes that control the exchange of Hg between the sediments and lake water. We first present data on spatial and temporal concentrations in the water column, sediments, pore water, and groundwater. These data set the context for a subsequent discussion of the chemical and physical processes responsible for the transport of mercury across the sediment-water interface and are necessary for assessing transport rates. 

Figure 5. Comparison of groundwater mercury concentrations in samples taken from Pallette Lake using the dug-well and acrylic-tube sampling methods.

In another example [229], atrazine and one of its main by-products (deethylatrazine) have been removed in a large-scale 03/UV plant. The plant was fed with 70 m3 h 1 of groundwater (pH 7.2, 464 mg L 1 bicarbonate and 0.6 mg L-1 DOC). UV-C radiation was emitted from a medium-pressure mercury arc lamp with a maximum total electrical power of 10 kW and 1.2 kW maximum radiant power in the UV-C region. The maximum electrical power of the ozone generator was also 10 kW. Concentrations of atrazine and deethylatrazine in the plant inlet were 0.28 pg... 

---