1、翻译部分xx大学20xx届本科生毕业设计（论文） 第12页A preliminary study of coal mining drainage and environmental health in the SantaCatarina region, BrazilLuis F. O. Silva Marcus Wollenschlager Marcos L. S. OliveiraReceived: 22 September 2009 Accepted: 3 May 2010 Published online: 18 May 2010Springer Science+Business Med
2、ia B.V. 2010Abstract :The concentrations and loadings of major and trace elements in coal mine drainage (CMD) from 49 abandoned mines located in the coal fields of the Brazilian state of Santa Catarina were determined.The CMD sites typically displayed a wide spatial and temporal variability in physi
3、cal and geochemical conditions. The results of our CMD analyses in Santa Catarina State were used to illustrate that the geochemicalprocesses in the rock piles can be deduced from multiple data sets. The observed relationship between the pH and constituent concentrations were attributed to (1) dilut
4、ion of acidic water by nearneutral or alkaline groundwater and (2) solubility control of Al, Fe, Mn, Ba and Sr by hydroxide, sulfate, and/or carbonate minerals. The preliminary results of the CMD analyses and environmental health in the Santa Catarina region, Brazil, are discussed.Keywords :Brazilia
5、n coal mining Coal mine drainage Drainage management Environmental impactsIntroduction A coal mining project can be seen to be a valuable resource in terms of its contribution to the local and national economy and its associated impact on society (Sekine et al. 2008). However, the cost associated wi
6、th reclamation, mitigation, and monitoring of improperly controlled and abandoned mines can be staggering. In addition, one of the major environmental concerns related to coal mining is the contamination of surface and ground waters as a result of surface disposal of waste rock. These waste material
7、s typically contain variable amounts of sulfide minerals. After disposal, exposure to atmospheric oxygen and water results in sulfide oxidation and the formation of mine drainage with variable pH, SO4 2-, and heavy metal content. When coal is mined, pyrite is exposed to oxygen and water, setting off
8、 a series of reactions that can result in lowered pH (unless there are sufficient carbonates to neutralize acids produced by oxidation and hydrolysis) and the release of high concentrations of metals, such as iron (Fe), aluminum (Al), and manganese (Mn). Potentially toxic trace elements, such as ars
9、enic (As), mercury (Hg), lead (Pb), and selenium (Se), may also be released. In addition to causing poor water quality, mine drainage can affect the substrate of a stream. Ferrous iron (Fe2?) is oxidized to ferric iron (Fe3?) to form a precipitate on the substrate (commonly referred to as yellow boy
10、) in the presence of water when the pH is greater than about 3.5 (Rose and Cravotta 1998). In many minedrainage streams with a relatively high pH, precipitated iron and aluminum may coat the stream substrate and cause an unstable habitat for macroinvertebrates (Schmidt et al. 2002; Simmons et al. 20
11、05). The pH of a solution is an important measure for evaluating aquatic toxicity and corrosiveness (Cravotta 2008). The severity of toxicity, or corrosion, tends to be greater under low-pH or high-pH conditions than at near-neutral pH because the solubility of many metals can be described as amphot
12、eric, with a greater tendency to dissolve as cations at low pH or anionic species at high pH (Langmuir 1997). For example, Al hydroxide and aluminosilicate minerals have their minimum solubility at pH 67 (Nordstrom and Ball 1986; Bigham and Nordstrom 2000), and brief exposure to relatively low conce
13、ntrations of dissolved Al can be toxic to fish and other aquatic organisms (Baker and Schofield 1982). Anions, including SO4 2-, HCO3 - and, less commonly, Cl-, can be elevated above background concentrations in coal mine drainage (CMD) (Cravotta 2008), and polyvalent cations such as Al3? and Fe3? t
14、end to associate with such ions of opposite charge (Nordstrom 2004). Ion-pair formation, or aqueouscomplexation reactions, between dissolved cations and anions can increase the total concentration of metals in a solution at equilibrium with minerals and can affect the bioavailability and toxicity of
15、 metal ions in aquatic ecosystems (e.g., Sparks 2005). Eventually, the solutions can become saturated, or reach equilibrium, depending on the various sulfate, carbonate, or hydroxide minerals that establish upper limits for the dissolved metal concentrations. In this study, we analyzed 49 samples of
16、 abandoned CMD at mine dumps in Santa Catarina State, Brazil, identifying the geochemical processes which give rise to its acidic character and evaluating the effects of the selective spoil management on its characteristics. The variation in the water chemistry is also discussed within the framework of the results. This preliminary study of the existing CMD in Santa Catarina State relates to minerals exposed during coal mi
