Acid Rain Formation
Acid rain is mostly formed from the spontaneous chemical reaction between naturally occurring dioxides of sulfur and nitrogen (SO2 & NO2) in precipitation and oxygen and/or atmospheric water. The reaction produces sulfuric and nitric acids, respectively, which are further transferred to the soil and downstream through the wet deposition process. According to Qiu et al., the formation of sulfuric acid in the atmosphere is the most common form of acid rain (279). Sulfur deposits from industrial effluents and natural sources readily react with atmospheric oxygen according to equations i and ii. In addition, dry depositions of sulfur (IV) oxide readily react with water molecules from dew to form sulfurous acid, which is an intermediate product as seen from equations iii and iv. As sulfuric acid is a strong acid, there is further dissociation into H+ and SO2-2 ions, which form part of the precipitation.
Contribution of Carbon and Nitrogen
Notably, the deposition of dioxides of carbon and nitrogen into the atmosphere also causes acid rain by first forming weak carbonic and relatively stronger nitric acid intermediaries. From equation ii, it evident that the wet deposition process prolifically contributes to an increase in the H+ concentration of the soils and water bodies. The high concentration of the H+ ions is responsible for the acidity of the soil and lowers the P.H.
Causes of Acid Rain
Acid rain is a prevalent environmental issue, especially in the twenty-first-century owing to the high rate of industrial revolution and transformations. As a result, there is an increase in the emission of carbon, sulfur, and nitrogen into the atmosphere. These reactive molecules are mostly found in industrial effluents due to combustion of fossil fuels and they readily oxidize to the various acid-forming oxides for stability reasons. Other sources of these toxic compounds include volcanic eruptions, ocean spray effect, organic decaying matter, and smelted metal sulfides in metallurgy (Manahan 27). These oxides are the major precursor molecules for acid rain formation. Technically, uncontrolled dumping increases the probability of acid rain (Manahan 18).
Impact on Soil and Plant Life
Acid rain increases the acidity level of the soil by elevating the concentration of H+ ions. Acid rain occurs in various forms of precipitation as rainfall, fog, mist, and smog. When acid rain precipitations percolate through the soil, the high acid concentration is likely to sweep away the various essential and non-essential soil nutrients that support plant life in the event of chemical reactions (Li et al. 92). On the contrary, disintegrative reactions lead to chemical weathering and soil formation (Dixon et al. 1624). In the long run, the plant population is bound to reduce owing to the inability of the soil to provide the necessary nourishment to support cell growth and division (McGivney et al. 14). Similarly, when the soil is rich in calcium and limestone, it is of high alkaline and thus neutralizes the acid rain. However, in the case of intensive dumping, the level of soil acidity increases beyond self-neutralization. This phenomenon shows how human activities prolifically contribute to the occurrence of acid rain and the resultant ecosystem imbalance.
Impact on Ecosystem
Notably, nature relies on a balance. For instance, the vegetation within an ecosystem produces oxygen whilst utilizing Carbon (IV) Oxide in the event of photosynthesizing. On the other hand, animals take up the atmospheric oxygen through cellular respiration to produce energy in giving out CO2 (Chen et al. 149). Therefore, as acid rain constrains the growth of plants, the ecosystem is highly vulnerable to imbalance (McGivney et al. 14). Further, surface run-offs direct acidified precipitation into water bodies. Similarly, the deposition of acidic waters into rivers, lakes, and oceans increases the acidity of the water and renders these aquatic areas inhabitable by certain living organisms that cannot survive in highly acidic media. In extreme cases where the P.H of the waters drops below 5, it becomes unbearable for fish and other aquatic animals to live due to irritation and intoxication.
Solutions to Acid Rain
The effects of acid rain on soil chemistry, plant life, and the ecosystem at large are adverse. There is a need to address them accordingly by tracing and curbing the root cause of acid rains. It is an established fact that a larger assortment of atmospheric carbon, sulfur, and nitrogen emanates from domestic and industrial plants effluents. Despite the necessity of sensitization campaigns to spearhead environmental responsibility, it is difficult to get some role-players to comply. According to Chen et al., businesses hardly stop dumping when they can still profit (151).
The adverse effects of acid rain call for a stricter approach to curbing uncontrolled dumping in the atmosphere. Tax policies and laws should be used to enforce the provisions for acid rain prevention at the societal level to ensure compliance. In this case, businesses and expected to adhere to effluent treatment and recycling policies to avoid deposition of sulfur, carbon, nitrogen, and other toxic substances that contribute to acid rain formation. Harsh punishment for law offenders is expected to enhance compliance with the dumping policies to keep the levels of soil and water acidity within naturally containable limits.
Conclusion
In conclusion, acid rain is a naturally occurring phenomenon from the reaction between oxides of sulfur, carbon, or nitrogen with either oxygen or ozone. This process leads to the formation of the correspondent acid, which further dissociates into constituent ions through wet deposition mechanism. Eventually, there is an increased concentration of H+ ions in the soil or water bodies. The high level of acidity reduces the chances of survival for plants, soil macro and micro-organisms, and the aquatic life in general. Population decrease among various affected species leads to an ecological imbalance, which can be feasibly addressed through awareness, taxation, fines, and effective legislation (McGivney et al. 14). In other words, the policy that is designed to regulate industrial emissions should be legally binding and admissible in a court of law to scare those who are likely to violate.
Works Cited
Chen, Shutao, Xu Zhang, Yifan Liu, Zhenghua Hu, Xiaoshuai Shen, and Jingquan Ren. "Simulated acid rain changed the proportion of heterotrophic respiration in soil respiration in a subtropical secondary forest." Applied Soil Ecology 86 (2015): 148-157.
Dixon, Jean L., Oliver A. Chadwick, and Peter M. Vitousek. "Climate‐driven thresholds for chemical weathering in postglacial soils of New Zealand." Journal of Geophysical Research: Earth Surface 121.9 (2016): 1619-1634.
Li, Junhui, Chongjian Jia, Ying Lu, Suofang Tang, and Hojae Shim. "Multivariate analysis of heavy metal leaching from urban soils following simulated acid rain." Microchemical Journal 122 (2015): 89-95.
Manahan, Stanley. Environmental chemistry. Boca Raton, FL: CRC Press, 2017.
McGivney, Eric, Salim Belyazid, Therese Zetterberg, Stefan Löfgren, and Jon Petter Gustafsson. "Assessing the impact of acid rain and forest harvest intensity with the HD-MINTEQ model–Soil chemistry of three Swedish conifer sites from 1880 to 2080, SOIL Discuss." SOIL Discuss 10 (2018).
Qiu, Qingyan, Jianping Wu, Guohua Liang, Juxiu Liu, Guowei Chu, Guoyi Zhou, and Deqiang Zhang. "Effects of simulated acid rain on soil and soil solution chemistry in a monsoon evergreen broad-leaved forest in southern China." Environmental monitoring and assessment 187.5 (2015): 272.
