Alnuaimi 1 Eisa Alnuaimi CE 341 Cadwell 12/6/2016 Contaminant Transport in Ecosystems Introduction This paper focus on the study and review of the fate, degradation and transport of organic anthropogenic chemicals in an ecosystem at differentiated spatial scales that range from local to international. An emphasis is made on the utilization of molecular markers to study the pathways used. Identification is made on the various sources of pollutants and dominant degradation pathways are also highlighted and how this may affect the different classes of pollutants is mentioned (Balis et al. 56). A discussion is further made on the effects of the interaction between the inter-physical properties and biogeochemical environment in which these pollutants are released. Currently there is presence of a heightened awareness on the presence and effects of anthropogenic contaminants and especially their biological impact. Industrialized nations have tried to limit the use of such chemicals in their jurisdictions, however multinational companies are still using these chemicals in developing nations. The availability of permissiveness in use of these chemicals has been out of a combination of various factors that include low education levels and conflicting interests on economy and health. Case in point, in tropical environments the outbreak of diseases like malaria necessitates the use of chemicals to fight and kill mosquitoes using DDT (dichloro diphenyl tricholoroethane). The toxicity and effects of this chemical is well known. Elimination of DDT will only be realized if more cheaper and feasible options are made available. Various classes of compounds including organ chlorine compounds and polycyclic aromatic hydrocarbons like DDT and PAH respectively are in a category of chemical compounds that is descried as both being persistent and organic pollutants (Narayananand and Chandramohanakumar 76). The slow rate of degradation of these chemical compounds in the environment makes them persistent. These chemicals are lethal as they undergo bioaccumulation and bio concentration and when this happens the effects on a human system is quite pronounced and may include neurological and immunological disruption. Even worse and probably more fearful is that a good number of these chemicals are known to be carcinogenic. Alnuaimi 2 Input of organic pollutants in the ecosystem PAHs are emitted in the ecosystem after incomplete combustion of hydrocarbon fuels. There are also some natural sources to some of the PAHs that may include petroleum formation and seeps. PCBs are very stable at high temperatures and therefore the reference to use them in generators, flame retardants and transformers. PCCDs are the byproduct of paper mills as these factories use them to bleach paper, it is therefore not uncommon to find them in paper mill effluents. Agrochemicals are also a popular source of contaminants. Sources include organ chlorine compounds like DDT and pestsides such as lindane. Highly volatile compounds like carbon tetrachloride are also in the list. These pollutants can reach terrestrial and groundwater sources through air-water or water-air exchange processes. Differences in degradable and persistent pollutants are very arbitrary. If a pollutant is deemed to reside in the environment beyond a decade after initial use in the environment, it can be said to be a persistent pollutant. A pollutant that breaks down and deco poses in a matter of hours on the contrary is said to be degradable. When laboratory experiment and studies are conducted to evaluate degradability and persistence, it is important to capture the lab environment in which this is simulated as the specific environment in which these processes occur can alter the properties of degradability and persistency. Inherent properties of a chemical have to be taken into account when accessing persistence of a chemical compound. Most chemical contaminants emit a single type of or predominant compound into the environment. However most of these find their way into the environment as mixtures. Creosote as an example distillates into a chemical mixture with varied components of aromatic hydrocarbons. Pesticides are formulated in industries with closely related chemicals. A good example is the composition of hexachlorocylcohexane and chlordane (Connell et al. 56). These two are formulations of closely related isomers of hexachlorocyclohexanes (HCHs) and cis-chlordane. Mixtures may only contain a single class of chemicals or may also contain different varying classes of compounds. Sewage may contain not only nutrients of nitrogen and phosphorous that may lead to eutrophication of the environment, but may also contain household chemicals in quanitities that are identified as endocrine pollutants and pharmaceutical waste and toxic metabolites of pharmaceutical chemical compounds. In the past few decades, POP compounds have been identified as worthy of study and ubiquitous. However there is an emerging class of pollutants and contaminants that may require attention as well in the coming future due Alnuaimi 3 to a demonstrated ability to have pronounced impact on the ecosystem. These compounds include surfactants and pharmaceuticals. Surfactants like nonylphenols have proved that they can cause endocrine disruption events. These chemicals are used in macro amounts in soaps and detergents and will therefore appear in large amount in the environment. Pharmaceuticals are also metabolites that are in high amounts in the environment and their concentration is high enough to cause action. Little is known and documented on the occurrence of pathways and distribution of these contaminants in aquatic and terrestrial ecosystems. Research in this area is however gaining momentum and is receiving widespread attention in North American and Europe. Ecosystem transport pathways Pathways available to transport a contaminant in an ecosystem compartment and within ecosystems are dependent on the mode in which a pollutant gets discharged into the ecosystem and environment. For instance, soot particles first get emitted in the atmosphere after an incineration process. These particles may then be subjected to undergo washing out or atmospheric precipitation by rain and onto the soil or subterranean water sources. Type predominant transport mechanism is majorly a function of the chemical properties of the pollutant itself and on the biophysical and chemical properties of the environment in which this contaminant id released. Incineration and combustion is a chief way of introducing contaminants in the atmosphere. For this reason environmentalist’s advice accordingly that it’s wrong to incinerate garbage and other kind of garbage as this releases large quantities of contaminants in the air (McCarthy 76). A large number of substances have been detected and most of them even in trace amounts. Detections occur in gaseous state and finite particles from waste incinerations and combustion, spraying and a wide range of other activities depending on context, be it agricultural pesticide application or a manufacturing industry. In incidences of incineration a number of products are emitted in the atmosphere: metals, aid gases, and large organic products of incomplete combustion, noncombustible matter, oxides of nitrogen, sulfur and carbon. When these emissions are released directly into the atmosphere there is a huge chance that people living near an incineration facility are exposed and affected directly by inhalation or though ingestion of water and food sources in the vicinity after the sources are contaminated. Persistence and spatial scale Alnuaimi 4 It is possible for persistent contaminants to be spread beyond the source jurisdiction where they were emitted initially. A good example of such contaminants includes dioxins mercury and furans. This category of contaminants is known as semi volatile organic compounds and have vapor pressures that is below 10-2 -10-5 Pascals at ambient temperature. They also include some high pressure metallic compounds like mercury and low vapor pressure materials that re incorporated in fine particles. SVCs that are organic and persistent are mostly lipophilic and can readily be packed into lipid as well as carbon tissues of flora and fauna (Bard 24). If these particles and elements show tendencies to resistance of biochemical and physical degradation processes they can continue to exist in an unchanged state. These compounds are in a category being named as persistent organic compounds. It is possible for these compounds to be re-emitted from their deposited environment sinks in which they partition because of their vapor pressure. Scientists has posited that it is possible for POPs undergo a repeated re-emission and deposition from the soaked in environment, be it water, soil, animals and vegetation. Transport is effected in the vapor phase and adsorbed in the form of ambient fine particles. A strategy and effort to examine the use of pesticide POP in various parts of the globe was conducted by sampling barks of trees. This study revealed the transport of very persistent contaminants over vast distances. The recognition of POP over such huge distances has created and recognized a need to establish frameworks and management strategies that access dispersion, persistence and the potential adverse long term effects of contaminants on human beings and animals. A process that can also be used to calibrate field data as well as validate models adopted for control strategy and decision making. There are a lot of efforts in academia to transition to a more quantitative based study of characterization of POPs. These efforts have unfortunately been met by a number of several hindrance factors. Most importantly this transition to a quantitative based stud requires that a framework be modeled that includes coupled mass exchange at the existing environmental compartments in linkage of space time and time space dimensions as these greatly influence transport of contaminants over vast distances. There is also an apparent need to come up with high quality data to quantify the partitioning of contaminants present in large scale. All known measurements of transport of vapor-particles partitioning currently is known to have art factual biases due to sampling methods employed. Deposition and accumulation in soil Weathering action is responsible for forming soil from a mixture of rocks and minerals as well as other biochemical actions of living things. Soil is composed and made up of a mixture of several components that include Alnuaimi 5 water, air and solids. The percentage making up soil in the named above constituents determines the method in which a contaminant will exists and be transported in soil or even be transformed. It is possible for a contaminant to be lodged and get mixed in the water component of soil, the air in the solids. Soils are also heterogeneous on the vertical spill and a trench dug reveals that there are several different horizontal layers with varying colors and textures. Radioactive studies that have been conducted in in agricultural land management reveal that in total lack of any mechanical tiling of a piece of land falling atmospheric particles can increase and accumulate and are suspended from a surface soil layer (Mackay 98). Mechanical transport takes place in the longer term by animals and other plants. It is possible to transport particles on the surface mechanically in the horizontal direction by runoff water and other debris. Mass transport on the ground has also occurred as a result of wind erosion. Surface-soil contaminants are transportable by wind erosion, by mechanical movement deeper into the soil, by leaching, by diffusion, dissolution in runoff and volatilization to the atmosphere. Transfer on plant surfaces also occurs via resuspension and deposition. It is also quite possible to transform these compounds by photolysis by chemical degradation and degradation by microorganisms, both flora and fauna. Surface water and sediments Surface chemical water behavior is determined by a number of factors that include rate the velocity of the water system and chemical reactivity. Water transport is also a function of the particulate water body in consideration. In low concentration around natural water, contaminants exist in dissolved and sorbed phases. For slow moving water, advection and dispersion are important. When water is moving at fast speeds, advection influences mass translocation and all present substances will move uniform speeds as the rest of the water mass. Contaminants can also be stuck in debris on moving water and these ones may have to undergo a number of other processes that may altogether alter their stay of residence in water. Such processes include and are not limited to deposition, agglutination and sedimentation. To understand the transport of contaminant on surface water requires that one has a good knowledge in water movement, resuspension from the sediment and deposition to the sediment. Sediment is the soft layer of matter composed of a combination of water, minerals and other matter that rest at the bottom of a water body after deposition. Water sediment is characterized by two things, an upper layer that is characterized by a high degree of activity both biological and chemical. In the last layer, there is comparably lesser activity and chemicals are quite isolated from water. Resuspension and deposition of organic and mineral matter to Alnuaimi 6 sediments is likely to occur continuously in any kind of a water body and is an important mechanism for transfer of particle bound contaminants to the bottom of the sediment layer. Conclusion The world is becoming a more widespread and polluted place with the sources of pollutant having a widespread impact to vast distances due to transportation of contaminants through several agents that include wind and water. A framework and quality evidence based studies should be conducted to establish the real impact and reach of these contaminants. Due to the impact and persistence of some of the contaminants there is need to limit their use as well as develop cleaner cheaper and more efficient chemicals that will not have negative effects to the environment. Alnuaimi 7 Works cited Bard, Shannon Mala. "Global transport of anthropogenic contaminants and the consequences for the Arctic marine ecosystem." Marine Pollution Bulletin 38.5 (1999): 356-379. Blais, Jules M., et al. "Biologically mediated transport of contaminants to aquatic systems." Environmental Science & Technology 41.4 (2007): 1075-1084. Connell, Des W., et al. "Chemistry of organic pollutants, including agrochemicals." Interactions: Food, Agriculture and Environment-Volume II (2010): 290. Mackay, Donald, and Frank Wania. "Transport of contaminants to the Arctic: partitioning, processes and models." Science of the total environment 160 (1995): 25-38. McCarthy, John F., and John M. Zachara. "Subsurface transport of contaminants." Environmental science & technology 23.5 (1989): 496-502. Narayanan, T., and N. Chandramohanakumar. Sterols in mangrove sediments of the Cochin estuary. Diss. Cochin University of Science and Technology, 2006. CE 341 PROJECT RUBRIC: Paper & Presentation 1 Beginning or incomplete 2 Developing 3 Accomplished 4 Exemplary Introduction (Paper) Very little background information provided or information is incorrect Some introductory information, but still missing some major points Introduction is nearly complete, missing some minor points Results: data, figures, graphs, tables, etc. (Paper) Figures, graphs, tables contain errors or are poorly constructed, have missing titles, captions or numbers, units missing or incorrect, etc. Very incomplete or incorrect interpretation of trends and comparison of data indicating a lack of understanding of results Most figures, graphs, tables OK, some still missing some important or required features All figures, graphs, tables are correctly drawn, but some have minor problems or could still be improved Some of the results have been correctly interpreted and discussed; partial but incomplete understanding of results is still evident Occasional grammar/spelling errors, generally readable with some rough spots in writing style Almost all of the results have been correctly interpreted and discussed, only minor improvements are needed Sections in order, contains the minimum allowable amount of handwritten copy, formatting is rough but readable Audience has difficulty following presentation because student jumps around. All sections in order, formatting generally good but could still be improved All sections in order, wellformatted, very readable Student presents information in logical sequence which audience can follow. Student presents information in logical, interesting sequence which audience can follow. Student demonstrates full knowledge (more than required) by answering all class questions with explanations and elaboration. Discussion/ Conclusions (Paper) Spelling, grammar, sentence structure (Paper) Appearance and formatting (Paper) Frequent grammar and/or spelling errors, writing style is rough and immature Sections out of order, too much handwritten copy, sloppy formatting Organization (Presentation) Audience cannot understand presentation because there is no sequence of information. Subject Knowledge (Presentation) Student does not have grasp of information; student cannot answer questions about subject. Visual Aids (Presentation) Student uses superfluous visual aids or no visual aids. Verbal Techniques (Presentation) Group Work (General) Totals Student is uncomfortable with information and is able to answer only rudimentary questions, but fails to elaborate. Student occasionally uses visual aids that rarely support the presentation. Student mumbles, incorrectly Student's voice is low. Student pronounces terms, and speaks too incorrectly pronounces terms. quietly for audience in the back Audience members have of class to hear. difficulty hearing presentation. Cannot work with others in most Works with others, but has situations. Cannot share difficulty sharing decisions and decisions or responsibilities. responsibilities. 0-8=F, 9-16=D, 17-24=C, 25-32=B, 33-40=A Less than 3 grammar/spelling errors, mature, readable style Student is at ease and answers most questions with explanations and some elaboration. Introduction complete and wellwritten; provides all necessary background principles for the model All figures, graphs, tables are correctly drawn, are numbered and contain titles/captions. All important trends and data comparisons have been interpreted correctly and discussed, good understanding of results is conveyed All grammar/spelling correct and very well-written Student's visual aids relate to the presentation. Student's visual aids explain and reinforce the presentation. Student's voice is clear. Student pronounces most words correctly. Most audience members can hear presentation. Works well with others. Takes part in most decisions and shares in the responsibilities. Student uses a clear voice and correct, precise pronunciation of terms so that all audience members can hear presentation. Works very well with others. Assumes a clear role in decision making and responsibilities. Score
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