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I have guide questions and article. Answer each of them IN YOUR OWN WORD with three sentence at least and the schedule. Please DO NO COPY ANYTHING FROM THE ARTICLE to avoid plagiarism. Again do not use anything from the article. Read the article then answer them IN YOUR OWN WORD. Everything is in the article but do not copy paste

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Assignment #5 Acidification of Earth Intro Geochem Spring 2018 Due Thursday 4/26 - START OF CLASS (no late assignments) For the second read+discuss assignment you’ll be looking at various processes that contribute to acidification on a global scale. The paper for this assignment is as follows: Rice KC and Herman JS (2012). Acidification of Earth: An assessment across mechanisms and scales. Applied Geochemistry, 27(1), 1-14 Answer the questions below and bring the assignment and your copy of the paper to class on the discussion day, Tuesday 4/26. Things to keep in mind: • • • • Answer your questions on this assignment sheet – an electronic copy can be obtained on eCampus. Be precise in your responses and avoid vagueness No late assignments will be accepted Be vigilant against plagiarism 1. What are several natural processes that can cause acidification on large scales? 2. What is meant by an “acidifying” reaction? 3. What is a “hydrolysis” reaction? How does that impact acidification? 4. What are three words/terms you didn’t understand but looked up? Provide the word, the definition you found, and the citation of the source of your definition. 5. Based on Figure 1: a. What is the decrease in USA-Canada SO2 emissions between the maximum value and the final reported date? b. What is the increase in China SO2 emissions between date you reported in (a) and the final reported date? c. Go on line and see what the emisions rates of SO2 are for USA and China in 2018. Be sure to critically evaluate your source and cite it fully. Comment on how this compare with the data in the paper. 6. Coal Combustion: a. Based on Figure 2: Name 3 countries with the highest coal combustion and 3 countries with the lowest coal combustion. b. Go on line and see if this is still true – or how it has changed. Be sure to critically evaluate your source and cite it fully. Comment on how this compare with the data in the paper. 7. Several copper mines are mentioned in the article – Bingham Canyon in Utah, Berkeley Pit in Montana, and the mine in Chuquicamata Chile. Look these up online and provide 2 facts for each site. A following table is provided to help you summarize the article. The first row is completed to get you started – but you’ll have to summarize the rest yourself. Source Important reactions & where they occur Where does this process have the greatest impact? Coal mining & power production • Oxidation of pyrite – results in acid streams and surface waters Coal burning - US, China, India • Fossil fuel combustion – releases CO2 to the atmosphere Acid rain – eastern US, Europe, China • SOX and NOX released from fossil fuel combustion results in acid rain from the atmosphere; results in acidified soils depleted with base cations Applied Geochemistry 27 (2012) 1–14 Contents lists available at SciVerse ScienceDirect Applied Geochemistry journal homepage: www.elsevier.com/locate/apgeochem Review Acidification of Earth: An assessment across mechanisms and scales Karen C. Rice a,⇑, Janet S. Herman b a b U.S. Geological Survey, University of Virginia, Charlottesville, P.O. Box 400123, VA 22904-4123, USA Department of Environmental Sciences, University of Virginia, Charlottesville, P.O. Box 400123, VA 22904-4123, USA a r t i c l e i n f o Article history: Received 5 April 2011 Accepted 1 September 2011 Available online 10 September 2011 Editorial handling by R. Fuge a b s t r a c t In this review article, anthropogenic activities that cause acidification of Earth’s air, waters, and soils are examined. Although there are many mechanisms of acidification, the focus is on the major ones, including emissions from combustion of fossil fuels and smelting of ores, mining of coal and metal ores, and application of nitrogen fertilizer to soils, by elucidating the underlying biogeochemical reactions as well as assessing the magnitude of the effects. These widespread activities have resulted in (1) increased CO2 concentration in the atmosphere that acidifies the oceans; (2) acidic atmospheric deposition that acidifies soils and bodies of freshwater; (3) acid mine drainage that acidifies bodies of freshwater and groundwaters; and (4) nitrification that acidifies soils. Although natural geochemical reactions of mineral weathering and ion exchange work to buffer acidification, the slow reaction rates or the limited abundance of reactant phases are overwhelmed by the onslaught of anthropogenic acid loading. Relatively recent modifications of resource extraction and usage in some regions of the world have begun to ameliorate local acidification, but expanding use of resources in other regions is causing environmental acidification in previously unnoticed places. World maps of coal consumption, Cu mining and smelting, and N fertilizer application are presented to demonstrate the complex spatial heterogeneity of resource consumption as well as the overlap in acidifying potential derived from distinctly different phenomena. Projected population increase by country over the next four decades indicates areas with the highest potential for acidification, so enabling anticipation and planning to offset or mitigate the deleterious environmental effects associated with these global shifts in the consumption of energy, mineral, and food resources. Published by Elsevier Ltd. Contents 1. 2. 3. 4. 5. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Acidifying reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Acidification of the atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Emissions of S and N compounds and acidic atmospheric deposition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1.1. Decreasing emissions in the Western hemisphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1.2. Increasing emissions in developing countries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Other emissions to the atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Elevated atmospheric CO2 and ocean acidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Neutralizing reactions important in the oceans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Acidification of freshwaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Acid mine drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1.1. Metal ores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1.2. Coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Acidic atmospheric deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.3. Neutralizing reactions important in freshwaters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Acidification of soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.1. Fertilizer use for crop production. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.2. Neutralizing reactions important in soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 ⇑ Corresponding author. Tel.: +1 434 243 3429. E-mail addresses: kcrice@usgs.gov (K.C. Rice), jherman@virginia.edu (J.S. Herman). 0883-2927/$ - see front matter Published by Elsevier Ltd. doi:10.1016/j.apgeochem.2011.09.001 2 K.C. Rice, J.S. Herman / Applied Geochemistry 27 (2012) 1–14 6. Global aggregate effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction Natural sources of acidity in the environment range from volcanic emissions to drainage from newly exposed, sulfide-enriched igneous rocks to decomposing organic matter. A collection of reports on natural low-pH environments recently was published in this journal (Eppinger and Fuge, 2009). Natural acidic settings described by geochemists include those associated with oxidizing sulfide-rich mineral deposits of Cu (Verplanck et al., 2009), Zn, Pb and Ag (Graham and Kelley, 2009), and Fe (Kwong et al., 2009). Volcanic eruptions inject gaseous SO2 and NO into the atmosphere, where subsequent oxidation to H2SO4 and HNO3 supports aerosol formation (Pueschel, 1996) and causes acidification of local rainfall (Mather et al., 2004). Oxidation of natural organic matter, including petroleum (Borgund and Barth, 1994) and peat (Gorham et al., 1986), is well known to lower the pH of freshwater with organic acids. Unusually low-pH waters, however, are associated with parts of the landscape disturbed by human activities far more commonly than deriving from natural processes in pristine settings (Langmuir, 1997; Drever, 1997). In this review paper, the authors explore the nature and magnitude of acidification from human activities that exacerbate the oxidation and hydrolysis reactions of C, Fe, N and S. The objectives of this paper are to (1) describe and compare the mechanisms of anthropogenic acidification of Earth’s atmosphere, waters and soils; (2) ensure that specialists in each of the disciplinary fields touched on in this paper are aware of other mechanisms of environmental acidification; and (3) demonstrate that it is the many overlapping sectors of human activity that cumulatively cause acidification of Earth. To the authors’ knowledge, no attempt has been made to amass an assessment of all the major anthropogenic acidifying processes. Growing specialization of the sciences has tended to result in a lack of awareness of the useful information that exists in allied fields, limiting the success of comparative studies. This effort is presented to identify and quantify the most influential processes acidifying the environment across a range of spatial scales as a starting point for others to discuss and extend. The major anthropogenic causes of acidification of the environment are (1) electric power generation, whereby the combustion of fossil fuels affects the atmosphere and the resultant acid is widely distributed to the oceans, freshwaters and soils; (2) resource extraction, whereby the mining and processing of mineral and energy resources result in acid mine drainage into freshwaters and emissions from smelting contaminate the atmosphere and soils; and (3) food production, whereby the manufacture and application of N-based fertilizer affect the atmosphere through gaseous emissions as well as alter freshwaters and soils receiving runoff from agricultural fields. These alterations of Earth’s environment all increase with expanding human population and resource consumption and have direct consequences for the present and future chemical quality of the atmosphere, waters, and soils that support human life. 1.1. Acidifying reactions Biogeochemical reactions involving water in contact with the minerals of soil and bedrock and with the gases of the atmosphere result in solutes in aqueous solution, many of which subsequently undergo oxidation or hydrolysis (Hem, 1985). These two types of reactions are notable for their concomitant production of acidity. A typical oxidation reaction utilizes O2 in the atmosphere or dissolved in water as the oxidizing agent, and the electron-transfer reaction occurs by adding H+ to the aqueous environment (Stumm and Morgan, 1996). The abundant redox-sensitive elements C, Fe, N and S are intrinsic to human exploitation of energy, mineral and food resources, so oxidation of those elements is at the center of the analysis here. In the aquatic environment, sulfide undergoing oxidation to sulfate generates acidity (Garrels and Christ, 1965). Exposure of pyrite-containing rocks to O2 and water through human-induced disturbances associated with mining initiates oxidative weathering, þ FeS2 ðsÞ þ 7=2O2 ðgÞ þ H2 O ¼ Fe2þ þ 2SO2 4 þ 2H ; ð1Þ and the reaction equally describes the oxidative dissolution of marcasite and pyrrhotite. Frequently the dissolution of a mineral solid in water is followed by hydrolysis of the aqueous cation (Baes and Mesmer, 1976). The cation coordinates with hydroxyl ions (OH), the source of which is the self-dissociation of water. Once OH is taken up by the cation, H+ remains in solution, as in this hydrolysis leading to precipitation of an insoluble ferric oxyhydroxide solid phase Fe3þ þ 3H2 O ¼ FeðOHÞ3 ðsÞ þ 3Hþ ; ð2Þ or to formation of aqueous complexes of Fe(III) depending upon local geochemical conditions. The details of aqueous speciation and its interaction with mineral solubility and solution pH have been quantitatively presented in textbooks (Butler, 1998) and in a host of computerized geochemical models such as WATEQF (Plummer et al., 1976). The growth of organisms requires the fixation and reduction of C into biomass. Following death, oxidation proceeds in Earth-surface environments, ordinarily accelerated by microbial respiration CðsÞ þ O2 ðgÞ ¼ CO2 ðgÞ; ð3Þ although alternate electron acceptors are utilized in O2-restricted environments (Stumm and Morgan, 1996). In aquatic systems, CO2 gas dissolves, hydrates, and dissociates to form weak carbonic acid CO2 ðgÞ þ H2 O ¼ H2 CO3 ðaqÞ ¼ Hþ þ HCO3 ; ð4Þ which drives natural weathering reactions (Drever, 1997). The representation of decaying biomass as C in Eq. (3) is over simplified, because a typical soil organic matter composition is closer to C115N10S1.2P3 (Walker and Adams, 1958). Ammonium (NHþ 4 ) is the initial N-containing product of microbial decomposition of biomass, and reduced N can follow two pathways: (1) volatilize as gaseous NH3 and be oxidized in the atmosphere or (2) stay in the soil as NHþ 4 where it can undergo nitrification in the presence of O2 in the reaction NHþ4 þ 2O2 ðgÞ ¼ 2Hþ þ NO3 þ H2 O; ð5Þ which generates acidity (van Breemen et al., 1987). Overall, acidification of the atmosphere, surface waters, and soils results from oxidation reactions, primarily of reduced (1) C compounds, through fossil-fuel burning and a host of other anthropogenic activities; (2) Fe compounds, associated with extraction of mineral and coal deposits; (3) N compounds, through fossil-fuel burning and production and application of N-based fertilizers; and (4) S compounds, associated with removal of mineral and coal 3 K.C. Rice, J.S. Herman / Applied Geochemistry 27 (2012) 1–14 Table 1 The acidification processes exacerbated by human activities and their environmental effects. Element oxidized Means of human exacerbation Environmental effect Scale of effect Nature of effect Potential for natural amelioration Trends in human exacerbation S oxidation generates strong acid, H2SO4 Fossil-fuel combustion Acidic atmospheric deposition Regional Acidified receiving waters (freshwater); acidified soils Rate of bedrock weathering too slow to balance stress; depleted exchange capacity in soils Western hemisphere emission controls implemented and emissions reduced; global fuel consumption increasing S oxidation generates strong acid, H2SO4 Fe oxidation and hydrolysis releases free protons, H+ Mining coal and basemetal sulfides; processing and smelting metalsulfide ores Acid mine drainage Local Acidified receiving waters (freshwater) Bedrock weathering restricted to geochemically reactive substrate Global materials and energy consumption increasing C oxidation generates weak acid, H2CO3 Fossil-fuel combustion; deforestation; cement manufacturing; biofuel development Elevated CO2 in atmosphere Global Acidification of oceans Neutralization capacity of oceans inadequate Global fuel consumption increasing; deforestation increasing N oxidation generates strong acid, HNO3 Fossil-fuel combustion; production and use of N fertilizers Acidic atmospheric deposition Regional Acidified receiving waters (freshwater); acidified soils Rate of bedrock weathering too slow to balance stress; depleted exchange capacity in soils Global food production and consumption increasing; transportation sector increasing deposits and the burning of fossil fuel. The nature and scales of effect of each means of human exacerbation of acidifying processes are summarized in Table 1. Although the complex inter-relations among these numerous processes and the receiving media prevent a neat separation into individual components of the Earth-surface environment, this paper is roughly organized along the hydrological pathway of acidification of the atmosphere, followed by effects on surface waters, first the ocean and then freshwaters, and finally the effect on soils. 2. Acidification of the atmosphere Combustion of fossil fuels and various industrial and agricultural emissions of reduced C, N, and S compounds support oxidation reactions and the resulting acidification of the atmosphere (Table 1). The largest source of CO2 and SO2 released to the atmosphere is from combustion of coal for generation of electric power (Energy Information Administration, 1998). Additionally, significant atmospheric emissions derive from combustion of natural gas and petroleum, refining of crude oil, smelting of ores, burning of forests, and manufacture of chemicals, pulp and paper, steel, Al, and cement, all of which have different spatial scales and location of effect. For example, in Canada, the largest portion of SO2 emissions (>30%) derives from the base-metals smelt ...

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