Limestone runoff

Sulfur deposition and subsequent remobilization by incident rain for a limestone surface differs from that exhibited by a marble surface. This difference may be the result of larger porosity values of limestone compared to marble. Larger limestone porosity adsorbs a larger portion of incident rain than marble. Thus, fewer low-rain events occur for limestone. Where small rain-amount data are available for both limestone and marble, excess sulfate values consistently are lower for limestone runoff than for marble runoff. This observation suggests that limestone surface-accumulated sulfate is less mobile than marble surface-accumulated sulfate. 

Not all mine drainage or natural runoff from rock outcrops are acidic, even when extensive sulfide oxidation is present. Synthetic cyanide solutions, which are often used to extract gold and other metals from ores, can greatly increase the alkalinity of mining wastes and neutralize sulfuric acid (Craw et al., 1999). In other cases, the sulfuric acid is effectively neutralized by alkaline soils, limestones, dolostones, marbles, shams, or other carbonate-rich rocks (Pfeifer et al., 2004, 219 Razo et al., 2004 Lee, Lee and Lee, 2001, 491 Mendoza et al., 2006). Reactions between calcium carbonate and sulfuric acid may precipitate gypsum (CaS04 2H20). 

Calculate the composition of seepage water with and without considering evaporation assuming that the annual average precipitation in an area is 250 mm, the current evaporation is 225 mm and the surface runoff is 20 mm. Use the rainwater analysis of exercise chapter 3.1.2.1. Furthermore, there is an increased C02 partial pressure of 0.01 bar in the unsaturated zone. This unsaturated zone consists mainly of limestone and sandstone. 

In this paper, we describe an onsite weathering experiment designed to identify acid-rain increased dissolution of carbonate rock. This experiment is based on the measurement of the change in rainfall-runoff composition from the interaction of a rock surface with incident acid rain 2. The experiment involves conducting long-term exposures of two commercially and culturally important calcium carbonate dimension stones (i.e., Indiana Limestone (commercial name for Salem Limestone) and Vermont Marble (commercial name for Shelburne Marble)) (3-5). This technique appears to give a direct measurement of the chemical dissolution of carbonate rock from the combined reactions of wet and dry deposition. Preliminary results from the initial months of onsite operation are presented to illustrate the technique. 

Approximately one liter of rainfall-runoff solution was collected from each of three experimental racks following rainfall events. Limestone and marble reference rocks were in two of the racks a third rack without a rock was used as a control (hereinafter referred to as a blank sample). Runoff volume, specific conductance, and pH measurements were determined at the exposure site as soon as possible after collection, typically within a few hours. Samples then were filtered through a 0.45-micrometer pore size membrane filter, placed in a clean polyethlyene bottle, and sent to the U.S. Geological Survey laboratory in Denver, Colorado, for chemical analysis. Sample preparation, analytical procedures, and laboratory quality-control protocols are described by Skougstad et al. (6). 

Reddy, M. M. Werner, M. Chemical analysis of samples from a rainfall-runoff experiment using limestone and marble at Research Triangle Park, North Carolina," U.S. Geological Survey Open-File Report 85-630. 

For limestone, the weight losses were far in excess of expectations based on direct measurements of recession and on runoff chemistry. 

Emphasis in the field tests of stone briquettes is on the long-term damage suffered by exposed marble and limestone. Because the pH variations for the existing test sites are principally variations between one rain and the next rather than from site to site, the separation of the pH effect cannot presently be achieved (except possibly in runoff chemistry on individual rains). The annual... 

Limestones 10-120 Jennings (1983) rate may include mechanical erosion, rate increases with runoff... 

An initial and important distinction needs to be made between two microenvironments - exposed and sheltered. Exposed surfaces have water flow across their surfaces either from direct rainfall or from runoff or both. However the magnitude and frequency of this flow may vary between surfaces. Sheltered surfaces do not experience any water flow products of degradation cannot, therefore, be removed from the surface by water flow. This can result in the build-up of a crust of degradation products that could protect the limestone surface from further alteration. On an exposed surface, the build-up of any degradation products is likely to be temporary. Microenvironmental variations in exposure begin to define the type of degradation forms that can be expected to develop on different parts of the building. 

SPILL CLEAN-UP Smother release with wet sand, clay, or ground limestone shovel into suitable dry container control runoff and isolate discharged material. 

During the drainage period of drill hole FOj. S2, in its Ordovician system limestone aquifer, the total quantity of SO/ ion, mineralization, free CO2 and soluble solid tend to decrease, which indicates that the runoff condition of Ordovician system limestone aquifer becomes better along... 

Many areas may have a thick topsoil and rocks composed of sedimentary materials, Uke limestone, that can neutraUze or buffer the acid runoff, greatly decreasing the harmful effects. 

The other reason the Northeast is affected by acid rain is geological. When acid rain falls to Earth, it is possible for thick topsoil containing sedimentary materials—principally limestone (CaCOj)—to neutralize the sulfuric and nitric acid. Chemists would say that limestone has the ability to buffer acid runoff In that case, the water flowing into aquatic ecosystems would have a pH closer to 7 and would do much less harm. 

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