Emerging Soil Pollutants Problems - Literature review Example

Emerging soil pollutants: What is the way forward? Introduction Generally speaking, soil can be defined as the top layer of the earth’s crust that is composed of mineral articles, water, organic matter, living organisms and air (Petruzzelli, Gorini, Pezzarossa & Pedron, 2010). The concept of emerging pollutants refers to substances that are released in environments for which there are no current environmental monitoring regulations (Thomaidis, Asimakopoulos & Bletsou, 2012). Emerging soil pollutants have recently attracted widespread attention among scholars and practitioners who perceive the issue as a threat to the viability of future soil utility. One emerging soil pollutant is heavy metals. In recent years, heavy metals have presented a serious environmental issue for industrialized countries worldwide. This is founded on the fact that the continued release of heavy metals mostly from industrial establishments has led to severe contamination of soil. The presence of metals such as Cu and Zn in soil is considered natural in low concentrations. However, these metals have the potential to become toxic at high concentration levels and thus have a detrimental impact on human health (Petruzzelli, Pedron, Rosellini, Tassi, Gorini, Pezzarossa & Barbafieri, 2013). This is just one example of an emerging soil contaminant among others that will be explored in the sections to follow. However, it is imperative to first discuss the background of the topic on emerging soil pollutants in terms of pollutants, problems, clean up technologies and management. Pollutants and problems A diverse array of emerging soil pollutants have recently attracted increased attention, most notably from environmental pressure groups and policy makers. This is founded on the adverse effects which are caused by these pollutants both to plants, animal as well as human health. Some of the most notable pollutants are heavy metals, such as mercury, which has been discussed in the previous section. Scholars like Pedron, Petruzzelli, Barbafieri & Tassi (2013) have determined that mercury is an extremely toxic non-essential element, and considered it to be a global environmental pollutant based on its capability to undergo long-distance transportation in the atmosphere. According to Petruzzelli et al, (2013), the rudimentary chemistry of mercury in soil is typified by diverse reactions which entail adsorption and release from solid phases. Scholars such as Vidal, Santos, Abrao, Rodriguez and Rigol (2009) as well as Vistoso, Theng, Bolan, Parfitt and Mora (2009) among others have inferred that absorption processes with significant influence on the mobility of metals and bioavailability are of fundamental importance to soils. This is founded on the fact that these processes regulate the transfer of metals through the food chain from the soil and water via plants and animals to humans as the final link as well. Additionally, these processes regulate the leaching of heavy metals to groundwater supplies as well as the surface which has become a core concern among environmentalists. The diabolical impact of heavy metals absorption processes were evident in a research on the distribution of Zn, Mn and Cu among other metals found in soil that was undertaken in Abeokuta, Southwestern Nigeria (Azeez, Mesele, Sarumi, Ogundele, Uponi & Hassan, 2013). Most of these heavy metals are industrial effluents that are disposed on land and lead to pollution of farmland soil in the environs, as well as groundwater, which is a relatively new area of research. Another core pollutant derives from recent technologies that have been developed in the recent past to curb the impacts of increased carbon concentration in the atmosphere. One of these technologies is carbon storage and capture (CSC). According to Hamerlinck, Wyckoff, Oakleaf and Polzer (2010), carbon capture and storage (CCS), which is sometimes referred to as carbon capture and sequestration (CCS), can be understood as the long-term isolation of anthropogenic sources of carbon dioxide (CO2) from the atmosphere. The technology of CCS has been revealed to have positive impacts on the reduction of carbon composition in the air. This is through the minimization and eventual eradication of growing threats associated with climate change. However, CCS has been found to include some inherent risks associated with potential carbon leakage from underground carbon storage sites. Research has revealed that plants can be extremely negatively affected by an increased CO2 concentration in soil, which is an issue related to the potential leakages of CCS. Concentrations of CO2 in soil above 5% can be harmful to the growth of plants, while concentrations above 20% have the possibility of killing the plants (International Energy Agency, 2008). The other class of emerging soil pollutants is organic pollutants (Ops), which have recently received increased attention in the wake of elevated manufacturing and industrialization processes. Both of the latter processes have been credited for resulting in the release of elevated amounts of Ops into the environment and culminating in detrimental soil contamination (Huang, Xu, Cheng, Lu & Zhang, 2012). These Ops include DDT, organic detergents, Cyanide and phenol, among others (Wei, 2011). Organic pollutants, and of these mostly hydrophobic organic compounds (HOC), have been revealed to have an extended retention time with the potential of penetrating into the soils and groundwater supplies. This is due to the low solubility, semi-volatility, high lipophilicity, and low degradability of HOCs, which thus have the capacity to cover wide areas and remain in environmental media (mainly soils) for extended periods of time (Huang et al., 2012). These characteristics are best epitomized by hydrocarbon pollutants such as benzene, which are of specific concern due to the fact that they are problematic for microorganisms to degrade under anaerobic conditions (Huang, 2010), and their cumulated amounts in soil lead to extensive soil pollution. The resultant soil pollution emanating from these Ops has recently become a serious issue in regards to food systems, public health and ground water. The last emerging soil pollutant that will be explored in this section is nuclear waste. The potential of nuclear waste to lead to widespread soil pollution has long been recognized, most notably in the discharge of radionuclides into the Techa River (1949-1953), as well as the Kyshtym (Southern Urals, 1957) and Chernobyl (Ukraine, 1986) accidents among others, (Aleksakhin, 2009) which have revealed the devastating impacts of radionuclides in regards to soil pollution. Recent nuclear accidents, for instance in Japan (2011) among others, have reignited discourse on nuclear wastes’ contribution to soil pollution. The increased efforts of various countries to opt for nuclear energy due to diminishing fossil fuels increases the likelihood of elevated nuclear accidents in the future that are bound to increase the rate of soil pollution in different parts of the world. Clean up technologies Over the past several years, different technologies have been proposed as having the capacity to eradicate the impacts of the above soil pollutants. One such technology is Electrokinetic (EK) remediation. EK is a green remediation technology that was developed over the last decade and has already received extensive utilization in the treatment of soils that are contaminated by Ops and heavy metals. EK has thus evolved into becoming a fundamental development in soil remediation and has proceeded to show promising application prospects (Huang, 2012). Different scholars, for instance, Dong, Huang, Xing and Zhang (2013) have been cognizant of the fact that the successful remediation of soil contaminated by both organics and heavy metals is a challenging task. This is founded on the fact that heavy metal pollutants in the soil can moderately or totally suppress normal heterotrophic microbial activity and therefore impede the biodegradation of organics. However, different studies have pointed to the fact that the EK process is both cost-effective and promising in its ability to remove heavy metals and organic pollutants from soils. Another clean-up technology is Phytoremediation. This technology is a novel strategy with the capacity of removing toxic heavy metals from soils through a hyperaccumulator plant species. Different scholars and practitioners have approved this technology as being not only cost-effective, but also eco-friendly in efforts to reclaim soils that have been contaminated with heavy metals as a result of developmental activities such as the discharge of industrial effluents (Mojiri, Aziz, Aziz, Selamat, Gholami & Aboutorab, 2013). Generally speaking, phytoremediation entails the cultivation of genetic plants that have the capacity to absorb pollutants in soils. Such plants have been cited as having the ability to remove organic contaminants from soils in three rudimentary ways, including the direct absorption, degradation and transformation of pesticides, the secretion of enzymes by root plants that have the ability to degrade pesticides, and lastly, through the secretion of organic acids by plant roots, which then proceed to promote microbial growth and the reproduction of surrounding roots that eventually aid in the degradation of organic pollutants (Wei, 2011). The high efficiency, cost-effectiveness, and eco-friendliness of phytoremediation technology was made evident in a case study on G. pseudochina (L.) DC. growing in a Zn/Cd contaminated area of a Zinc mine. The study revealed G. pseudochina (L.) DC. to have adequate properties for use as a Zinc hyperaccumulator in Thailand, and therefore a solution to the pollution problem caused by the heavy metal (Nakbanpote, Panitlertumpai, Sukadeetad, Meesungneon & Noisa-nguan, 2010). Other scholars such as Marques, Rangel and Castro (2009) believe that increased efforts ought to be undertaken to enhance phytoremediation technology. Based on their recommendations, Microbiota from the rhizosphere can play a fundamental role in these efforts. Additionally, the utility of genetic engineering can also be integral in elevating the success of the phytoremediation technology. Management There are several interventions that can be instituted to manage emerging soil pollutants in the contemporary world. The above section has evidenced the detrimental effects of accumulation of CO2 in soil as a result of leakages following CCS processes. One central management strategy involves the implementation of strong monitoring, verification and accounting (MVA) tools. These tools are aimed at containing permanent storage of CO2 within a geological formation through monitoring abilities that are both reliable and cost-effective (Plasynski, Litynski, McIlvried, Vikara & Srivastava, 2011). Such tools are instrumental in managing CO2 leakages that contribute to soil pollution. In regard to emerging soil pollutants related to nuclear waste, Stakeholders in the development of nuclear energy around the world would be smart to embrace prudent safety approaches when dealing with nuclear waste. Such efforts are integral not only to encourage the prevention of dangerous approaches to harnessing nuclear energy in other countries, but also to ensure the input of stakeholders in the management of any soil pollution impacts that derive from the discharge of radionuclides into soils. Stakeholders can engage in research and development (R&D) to develop prudent mechanisms of coping with the discharge of nuclear waste into soils. This is also a key strategy in the management of soil pollution impacts caused by radionuclides in the case of a nuclear accident. Conclusion The preceding analysis has explored various types of emerging soil pollutants, including heavy metals, organic pollutants and radionuclides, as well as accumulated CO2 after leakages emanating from carbon capture and storage processes. This review has also explored the various problems associated with these emerging soil pollutants both in plant, animal and human life. Additionally, it has explored various clean-up technologies essential to solving the problems emanating from these emerging pollutants. Some of the most notable technologies include Electrokinetic (EK) remediation, which has already been extensively utilized in the treatment of soils contaminated by Ops and heavy metals, as well as phytoremediation technology, which entails the cultivation of genetic plants with the capacity to absorb pollutants in soils. Lastly, this analysis has explored several management strategies for these emerging soil pollutants. These include the adoption of robust monitoring, verification and accounting (MVA) tools to minimize soil pollution risks associated with leakages after CCS processes, as well as embracing prudent safety approaches when dealing with nuclear waste by all stakeholders in the sector. References Aleksakhin, R.M. (2009). Radioactive contamination as a type of soil degradation. Eurasian Soil Science, 42(12), 1487-1498. Azeez, J., Mesele, S., Sarumi, B., Ogundele, J., Uponi, A & Hassan, A. (2013). Soil metal pollution as a function of traffic density and distance from road in emerging cities: a case study of Abeokuta, southwestern Nigeria. Archives of Agronomy and Soil Science, 1, 1-21. Dong, Z., Huang, W., Xing, D., & Zhang, H. (2013). Remediation of soil co-contaminated with petroleum and heavy metals by the integration of electrokinetics and biostimulation. 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Wei, L., (2011). Soil Pollution Issue in Environmental Impact Assessment about Standard Urban Development Project. IAIA11 Conference Proceedings, 28 May- 4 June 2011, Puebla, Mexico: Centro de Convenciones,   Read More