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Prior Notice and Consultation System
The Prior Notice and Consultation procedure (proposed by the Great Lakes Charter) would provide each State and Province in the basin an opportunity to review, discuss, and support or oppose any major new or increased diversion or consumptive use of the water resources of the Great Lakes basin. The Prior Notice and Consultation rule would apply to any new or increased diversion or consumptive use of the Great Lakes basin water resources that exceeds 5 million gallons per day in any 30-day period. To participate in the process, the State or Province must have authority to manage (permit, regulate, or allocate) water withdrawals involving a total diversion or consumptive use of Great Lakes basin water in excess of 2 million gallons per day in any 30-day period. This is in addition to the ability to provide accurate and comparable information on water withdrawals that average more than 100,000 gallons per day in any 30-day period. Since the Charter was signed, New York State, for example, has written legislation to meet these criteria.
The regional water-use data base is designed to provide accurate and timely data on withdrawals, diversions, and consumptive uses in the Great Lakes-St. Lawrence River basin. It may also be used to predict the effects on lake levels of proposed withdrawals, diversions, and consumptive use. Hydrologic models currently operated by the U.S. Army Corps of Engineers, Environment Canada, the Great Lakes Environmental Research Laboratory, and the University of Wisconsin, for example, could incorporate data from the regional data base for use in other predictive studies. If the participants choose to develop the regional data base into a sitespecific program, more options will be available for using the data base as a waterresources management tool.
The Great Lakes Charter is a significant document that proclaims the joint desire of the United States and Canada to preserve, conserve, and manage the water
resources of the Great Lakes-St. Lawrence River basin. This good-faith agreement calls for use of the rights and responsibilities of individual States and Provinces for the good of the whole region.
The proposed Prior Notice and Consultation procedure would permit group review of major withdrawals and diversions in relation to competing interests, future plans, and environmental considerations. An integral part of this procedure, and also a prerequisite to participation, is the collection and transmittal of water-use data to the Great Lakes Regional WaterUse Data Base. The data base is intended to gradually become a reliable source of current water-use data available for waterresources planning, management, and forecasting.
Effects of Acid Rain on
By Michael M. Reddy and
The various manmade and naturally occurring materials that are used in construction are subjected to changing natural factors that include temperature, wind, humidity, rain, dew, snow, and solar radiation, all of which may contribute to the gradual deterioration of these construction materials. At many locations, these materials are also subjected to varying quantities of pollutants, including oxidants (such as ozone), acid precursor gases (such as oxides of sulfur and nitrogen), particulate matter, and acid rain. Depending on their concentration, some of these pollutants may significantly increase the rate of deterioration of certain materials. Damage to limestone and marble building materials by air pollution and acid rain has been reported by a number of investigators. Such damage may occur in many places in the Eastern United States. The balusters on the west face of the Pan American Union Building, located at 17th and C Streets Northwest, Washington, D.C., for example, have been damaged by air pollution (fig. 16). On other parts of the west face of the Pan American Building that receive direct rainfall, rainfall appears to be dissolving the stone. This stone damage process appears to be accelerated in areas affected by acid rain.
One major question that remains to be resolved is: What are the relative contributions of air pollution and acid rain to observed stone damage? In order to understand and predict the pollution-caused damage, two tasks need to be addressed. First, the extent of damage to a particular material caused by exposure to pollutants needs to be measured during conditions that are equivalent to actual commercial and cultural use. Second, whether this effect causes earlier replacement than usual or frequent repair must be determined. If this is the case, an economic value can be placed on reducing the pollutant. This analysis is a complicated one and, to date (1987), has not been completed for any building material. The work of the U.S.
Geological Survey, in conjunction with the National Acid Precipitation Assessment Program's Materials Effects Task Group, primarily is to assess the incremental damage to building materials caused by the presence of acid rain and oxidizing pollutants. At present, scientists are unable to differentiate materials degradation caused by pollutants from that caused by natural weathering. Such information is essential to establish a satisfactory inventory of materials at risk and to analyze the economic effect of materials degradation. The ultimate goal of the USGS contribution to the Materials Effects Task Group is to provide an understanding of the incremental damage of acidic pollutants.
Onsite Exposure Studies
During onsite experiments that began in 1982, all limestone and marble samples were subjected to similar exposure at five research sites: Research Triangle Park, North Carolina; Washington, D.C.; Chester, New Jersey; Newcomb, New York; and Steubenville, Ohio. In 1984, Indiana limestone and Vermont marble were added to the onsite study. A typical
site, located in Washington, D.C., is shown in figure 17. A rack used to hold the exposed stone is illustrated in figure 18.
Material samples are analyzed annually by a variety of techniques to measure physical and chemical changes on the sample surfaces. In addition, runoff is collected from the limestone and marble (carbonate rocks) and roughened glass (control) surfaces. When rainfall runs off a marble surface, minimal porosity restricts acid reaction with the carbonate mineral to the surface moisture zone. Chemical analysis of the runoff water provides immediate measurements of the material removed by dissolution of the stone sample. Chemical analysis of the runoff solution also provides a measure of the solubility of deposition and corrosion products under various environmental conditions. Surface moisture
alone may be a major factor in limestone and marble deterioration. Two other processes, which also involve moisture on the stone surface, that may also be important are the direct dissolution of the stone surface by sulfuric acid present in the rain and the adsorption of sulfur dioxide gas by the surface moisture layer and subsequent chemical reaction. Reactions of sulfur dioxide adsorbed at the stone surface are not well understood at the present time. The stone surface can be damaged by sulfur
dioxide even before the gas oxidizes.
Air quality, meteorological conditions, chemical substances in rain, and chemical composition of particulate matter are monitored simultaneously at all sites. Results of these measurements are added to a large data base. The data base will provide annual, monthly, and seasonal averages; maximum and minimum concentrations during storms; and hourly records of gaseous pollutants.
Damage to Stone Surfaces
Figure 18. Isometric projection of a single stone-exposure rack; racks are mounted in pairs and there are four sets per research site.
The mineralogy of the limestone and marble samples used during the test program has been determined by petrographic and surface chemical-analysis techniques. These techniques are used initially and again after each year of exposure to identify the reaction products (for example,
gypsum) of limestone and marble and acidic pollutants. These techniques also provide information on the variation and depth of chemical change across the stone surface. The top and bottom surfaces of the stone specimens are sampled in 0.01-inch layers and are chemically analyzed to determine chemical changes caused by exposure to pollutants.
Gypsum forms on the stone surfaces when calcium in the stone reacts with sulfur-containing pollutants in the atmosphere. Initial onsite experiments indicate that little gypsum accumulates on the exposed upper surface; the amounts accumulated probably represent only the most recent atmospheric conditions (since the last intense rain). Significant accumulations of gypsum were observed on the sheltered underside of the test specimens. Mass-spectrographic analyses of the sulfur in the gypsum indicate that the sulfur resembles atmospheric sulfur, not sulfur indigenous to limestone and marble.
Chemical-dissolution effects are also determined by analyzing runoff collected from stone samples. The types and rates of reaction involved in the degradation of limestone and marble are being determined by collecting and chemically analyzing runoff from slabs exposed at each of the research sites. Initial results indicate that increased dissolution depends on the volume and the hydrogen ion concentration of
the rain. The product of these two variables, hydrogen ion loading, can be expressed in milliequivalents of hydrogen ion deposited per unit area of stone surface. A plot of stone surface recession values (per rain event) as a function of hydrogen ion loading for both limestone and marble samples at the New York, New Jersey, and North Carolina research sites, acquired during summer and fall 1984, demonstrates the direct relation between surface recession and hydrogen ion loading (fig. 19). However, no differences in recession rate for the two types of stone could be discerned from these data. Weight-loss measurements indicate that additional damage to limestone occurs because of granular disaggregation.
Limestone and marble exposed for 1 year and for several years are characterized as to weight loss and color change. These materials are also spectroscopically studied to determine surface recession and roughening caused by weathering. Initial experiments on freshly quarried stone indicate surface recession rates ranging from 0.0004 to 0.0007 inch per year. These recession rates agree with mass-loss estimates inferred from runoff studies, specifically for marble, indicating that surface recession by mechanical grain loss is probably small compared with recession by chemical dissolution. These results were determined for materials exposed at the four research
Figure 19. Stone surface recession for limestone and marble versus hydrogen ion loading (in milliequivalents per square meter) at Newcomb, New York; Chester, New Jersey; and Research Triangle Park, North Carolina, during summer and fall 1984.
sites (including Washington, D.C.) and are not indicative of the higher rates that might be expected in more polluted environments.
Nondestructive near-infrared spectroscopic methods have been developed for measuring gypsum accumulation on surfaces of buildings and monuments. The method has been calibrated by measuring the buildup of gypsum on the samples at the research sites. Measurements over the past 2 years have demonstrated that the technique can accurately measure the gypsum accumulation on the protected surfaces of the test materials. This method ultimately can be used to assess the differential accumulation of gypsum on buildings and monuments and will be useful in translating the results from the onsite and laboratory experimental program samples to verify measurements of gypsum on real structures.
An atmospheric reaction chamber is currently under construction to determine the environmental factors that influence the delivery of gaseous pollutants to carbonate stone. The chamber is designed to deliver radioactively labeled sulfur dioxide to stone surfaces under controlled conditions of relative humidity, pollutant gas concentration, temperature, and gas-flow velocity. The chamber experiments should provide good estimates of the drydeposition flux of sulfur dioxide to stone surfaces as a function of the controllable environmental parameters. The effects of changes in stone textures, composition, and weathering on the delivery of pollutants to carbonate surfaces will also be determined. In the future, the experiment will expand to determine the drydeposition flux of labeled nitrogen oxides.
The experimental investigations currently underway within USGS laboratories are expected to define mathematical relationships that quantify the effects of acid deposition on carbonate stone that are in addition to natural background rates of degradation. These functions are to be used for the development of an economic model for materials degradation as required by the National Acid Precipitation Assessment Program, which ends in fiscal year 1990.
By Robert J. Gilliom
Agricultural drainage problems in the western San Joaquin Valley of central California have attracted national attention since 1983, when selenium in water from subsurface tile-drain systems was found to have toxic effects on waterfowl at Kesterson Reservoir. Kesterson Reservoir received drain water containing an average of about 300 micrograms per liter ((xg/L) of selenium from about 8,000 acres of tiledrained farmland from 1981 to 1986. Drain water from about 77,000 acres of additional tile-drained farmland, north of the area that contributed drain water to Kesterson, eventually flows to the San Joaquin River. Flow of this drain water to the river occurs mainly through two tributaries, Mud and Salt Sloughs. Recent U.S. Geological Survey studies indicate that water from individual drainage systems, which discharge to waterways that eventually reach these sloughs or smaller tributaries, contains selenium concentrations ranging from less than 10 to 4,000 |i.g/L, with mixtures of these waters containing concentrations generally ranging from 20 to 100 n-g/L.
Future decisions on how to manage subsurface drain water in the area, and on how to protect the water quality of the San Joaquin River, depend on understanding the sources, concentrations, and transport of selenium in the river. This study, a first step toward achieving this goal, was done during low-flow conditions when dissolved contaminants, such as selenium, often have their greatest effect on water quality.