Due to the increase in demand and production for electronic products in the past decades, many problems become apparent regarding the whereabouts of the ever rising amount of electronic waste (e-waste). A growing supply of this waste is illegally exported to recycling facilities in developing countries in order to salvage reusable materials and traces of precious metals. In these foreign facilities, open burning and acid stripping practises take place, but along with recovering the prize comes the release of pollutants and toxic heavy metals. Not only do these contaminants cause health problems for the site workers, they also negatively affect the surrounding environment, including fields, rivers, soils, and sediments (Wang et al., 2009).
A recent study on human exposure to heavy metals in an electronic waste recycling area, published in Bioresource Technology during 2009, suggests that scalp hair can be used as an indicator on the exposure of heavy metals and toxic elements to humans. The six researchers, Thanh Wang, Jianjie Fu, Yawei Wang, Chunyang Liao, Yongqing Tao, and Guibin Jiang, believe that since studies on the potential exposures (both occupationally and environmentally) due to e-waste recycling activities are inadequate, it is important to be able to examine these residential exposures using the least invasive and hazardous, but most convenient techniques. They proposed that human hair scalp could be used to assess the amounts of e-waste contaminants that are exposed and state that their study is one of the very few that deals with “human exposure to trace elements and heavy metals associated in areas with e-waste recycling” (Wang et al., 2009).
The study was purposefully chosen to take place in the south eastern Chinese province Taizhou, where residents have been directly or indirectly involved with a local e-waste recycling site that has been in existence for almost two decades. Hair samples, which were collected from volunteer participants during their routine sessions at nearby barber shops, were analyzed using the external standard calibration method to detect total concentrations of arsenic, barium, cadmium, chromium, copper, manganese, nickel, lead, and, vanadium (Wang et al., 2009). These samples were then compared with samples from two cities located about 130km north and 160km northwest of Taizhou.
The results showed that all of the mentioned elements above were found at higher levels than those in the controlled areas except for arsenic and vanadium. The researchers also stated that compared to non-occupationally exposed populations in Sweden and France, the element levels were all greater, especially lead, which proved to show 80 times higher levels (Wang et al., 2009).
From these results, Wang and his co-researchers concluded that human scalp hair can be used to determine the exposure of toxic heavy elements and metals to residential and occupational personnel directly or indirectly involved with e-waste recycling areas. It provides a non-invasive and cost-effective method, and is beneficial because by knowing the levels of exposure, scientists can further their knowledge on the negative effects of unregulated recycling practises such as open burning and acid stripping.
Reference
Wang, T. et al. (2009) Use of scalp hair as indicator of human exposure to heavy metals in an electronic waste recycling area. Environmental Pollution, issue 157, March 2009. http://journals2.scholarsportal.info/tmp/12866323311903835193.pdf. Accessed 08 October 2009.
Monday, October 12, 2009
Chasing Nature
If someone were to ask you, ”What do helicopters, hypodermic needles, airplane wings and sonar have in common?”, do you think you could come up with the answer? At first glance the answer may not seem clear, but upon closer inspection a hidden similarity emerges. While all of these items do represent enormous leaps in human technological advancement, the design behind them is by no means original. Millions of years before the notion of these technologies were even conceived, dragonflies and hummingbirds hovered in midflight, vipers injected venom through hollow fangs into unsuspecting prey and dolphins used echolocation to locate fish. In fact a vast majority of modern technology is directly copied from designs in nature. Despite our best attempts, these imitations always pale in comparison to the real thing. It is really not much of a surprise then, when technology fails to match the most complex biological processes which, in themselves took millions of years to develop through evolution
One of the most complex and intricate of these systems is the digestive tract, specifically that found in ruminants. Since the emergence of grass as a dominant plant species, ruminants have continued to be the dominant group of herbivores. The secret of this success lies in the unique digestive system of this group of animals. Cellulose, is one of the main components of grass and plant cell walls, and since it is primarily comprised of carbohydrates, it has a lot of stored potential energy. The trouble is that cellulose is very difficult to digest and as a result all of that stored energy is virtually unattainable. Ruminants however, have evolved a highly complex digestive system which can digest tough cellulose so that energy may be extracted. Recently, humans have also recognized the enormous energy potential of cellulosic plant biomass specifically in the production of ethanol. Ethanol has many industrial applications, but its primary use is as a fuel additive. When ethanol is added to fuel, the amount of hydrocarbon and volatile organic emissions decreases. Up until recently, corn has been the primary source of ethanol. Unfortunately, corn alone cannot supply the necessary amount of ethanol required for a worldwide demand. Consolidated bioprocessing(CBP) of biomass is a process which utilizes anaerobic bacteria to decompose and ferment cellulose plant biomass into ethanol. Currently, CBP systems still require many improvements before the process can become a viable ethanol production source. Researchers from the University of Wisconsin-Madison and the USDA-ARS-US Dairy Forage Research Center have set out to observe the digestive system of the cow, which has a very efficient cellulose digestive system, in order to determine how CBP systems can be improved. After observation, 3 main areas of improvement were identified:
1. Pre-treatment of the cellulose fibre
2. Anaerobic bacteria
3. Usage of by-products as possible alternate energy sources
Even for the species of bacteria which can produce cellulase, cellulose must first be pre treated in order to weaken the tough protein lignin found in the cell walls of plantcells. In CBP this is achieved chemically, however, the systems and the chemical agents all require significant costs. In addition, chemical pre treatment also results in the loss of some carbohydrate from the mixture as well as waste which requires disposal. The system in cows is much more primitive, yet more effective. By physically grinding the plant material, and then re-chewing the regurgitated cud, cows are able to reduce the particle size so much that there is an estimated 104 fold increase in total surface area(Weimer 2009). However, in order to thoroughly breakdown the cellulose cows were found to chew for 200 min/kg of fibre intake which adds up to 10-13 hours of ruminating per day or as high as 20 hours per day(Weimer 2009)! Remarkably the energy expended in ruminating is actually quite small. But currently there is no mechanical system which matches the efficiency of the cow in grinding plant biomass, so efforts are continuing to be focused on a chemical pre treatment. However, this research may provide the information which could be used in the future to create a more efficient grinding system which closely mimics the cow.
The process of cellulose hydrolysis is made possible by enzymes produced by anaerobic bacteria. In cows these vital bacteria are located in a large organ called the rumen where the chewed plant fibre can remain for up to 72 hours(Weimer 2009). This gives the bacteria in the rumen plenty of time to properly digest the treated plant matter. In the low-no oxygen conditions, fermentation occurs and the main products are volatile fatty acids(VFA), which the cow absorbs through its gut wall(Weimer 2009). The cellulose is degraded faster depending on the available surface area. Plant cell walls are composed of many different components and yet almost every single type of enzyme required to digest the material can be produced by at least one of the bacterial species found in the rumen. In contrast, artificial systems lack this diversity of microflora, and cannot digest plant matter as thoroughly as ruminants.
Perhaps the most important focus of this study was the examination of utilizing the fermentation by products other than ethanol as alternative energy sources. Two of the major by products produced by the fermentation process are methane and VFAs. Methane, which is excreted as gas by ruminants, could be captured in CBP systems and used as an alternate fuel source. VFAs on the other hand have a low volatility, but have a large amount of stored energy therefore have a potential as another energy source. Most systems currently focus on primarily ethanol production however, the addition of these by products could contribute enormously to the biomass energy yield.
Improvements on current CBP systems need to be made before this process becomes a viable source of ethanol. Current research provides a valuable insight regarding the direction to advance this technology. Equally important, the effort towards developing this technology also presents alternatives for waste management. For industries where high cellulose biomass is produced as waste such as agriculture, forestry or even maintenance of green spaces the advancement of CBP systems represents a potentially effective and even beneficial waste management strategy other than composting.
References
Weimer J. Paul, Russell B. James, & Muck E. Richard. (2009). Lessons from the cow: What the ruminant animal can teach us about consolidated bioprocessing of cellulosic biomass. [Lessons from the cow: What the ruminant animal can teach us about consolidated bioprocessing of cellulosic biomass] Bioresource Technology, 100(21), 5323-5331.
One of the most complex and intricate of these systems is the digestive tract, specifically that found in ruminants. Since the emergence of grass as a dominant plant species, ruminants have continued to be the dominant group of herbivores. The secret of this success lies in the unique digestive system of this group of animals. Cellulose, is one of the main components of grass and plant cell walls, and since it is primarily comprised of carbohydrates, it has a lot of stored potential energy. The trouble is that cellulose is very difficult to digest and as a result all of that stored energy is virtually unattainable. Ruminants however, have evolved a highly complex digestive system which can digest tough cellulose so that energy may be extracted. Recently, humans have also recognized the enormous energy potential of cellulosic plant biomass specifically in the production of ethanol. Ethanol has many industrial applications, but its primary use is as a fuel additive. When ethanol is added to fuel, the amount of hydrocarbon and volatile organic emissions decreases. Up until recently, corn has been the primary source of ethanol. Unfortunately, corn alone cannot supply the necessary amount of ethanol required for a worldwide demand. Consolidated bioprocessing(CBP) of biomass is a process which utilizes anaerobic bacteria to decompose and ferment cellulose plant biomass into ethanol. Currently, CBP systems still require many improvements before the process can become a viable ethanol production source. Researchers from the University of Wisconsin-Madison and the USDA-ARS-US Dairy Forage Research Center have set out to observe the digestive system of the cow, which has a very efficient cellulose digestive system, in order to determine how CBP systems can be improved. After observation, 3 main areas of improvement were identified:
1. Pre-treatment of the cellulose fibre
2. Anaerobic bacteria
3. Usage of by-products as possible alternate energy sources
Even for the species of bacteria which can produce cellulase, cellulose must first be pre treated in order to weaken the tough protein lignin found in the cell walls of plantcells. In CBP this is achieved chemically, however, the systems and the chemical agents all require significant costs. In addition, chemical pre treatment also results in the loss of some carbohydrate from the mixture as well as waste which requires disposal. The system in cows is much more primitive, yet more effective. By physically grinding the plant material, and then re-chewing the regurgitated cud, cows are able to reduce the particle size so much that there is an estimated 104 fold increase in total surface area(Weimer 2009). However, in order to thoroughly breakdown the cellulose cows were found to chew for 200 min/kg of fibre intake which adds up to 10-13 hours of ruminating per day or as high as 20 hours per day(Weimer 2009)! Remarkably the energy expended in ruminating is actually quite small. But currently there is no mechanical system which matches the efficiency of the cow in grinding plant biomass, so efforts are continuing to be focused on a chemical pre treatment. However, this research may provide the information which could be used in the future to create a more efficient grinding system which closely mimics the cow.
The process of cellulose hydrolysis is made possible by enzymes produced by anaerobic bacteria. In cows these vital bacteria are located in a large organ called the rumen where the chewed plant fibre can remain for up to 72 hours(Weimer 2009). This gives the bacteria in the rumen plenty of time to properly digest the treated plant matter. In the low-no oxygen conditions, fermentation occurs and the main products are volatile fatty acids(VFA), which the cow absorbs through its gut wall(Weimer 2009). The cellulose is degraded faster depending on the available surface area. Plant cell walls are composed of many different components and yet almost every single type of enzyme required to digest the material can be produced by at least one of the bacterial species found in the rumen. In contrast, artificial systems lack this diversity of microflora, and cannot digest plant matter as thoroughly as ruminants.
Perhaps the most important focus of this study was the examination of utilizing the fermentation by products other than ethanol as alternative energy sources. Two of the major by products produced by the fermentation process are methane and VFAs. Methane, which is excreted as gas by ruminants, could be captured in CBP systems and used as an alternate fuel source. VFAs on the other hand have a low volatility, but have a large amount of stored energy therefore have a potential as another energy source. Most systems currently focus on primarily ethanol production however, the addition of these by products could contribute enormously to the biomass energy yield.
Improvements on current CBP systems need to be made before this process becomes a viable source of ethanol. Current research provides a valuable insight regarding the direction to advance this technology. Equally important, the effort towards developing this technology also presents alternatives for waste management. For industries where high cellulose biomass is produced as waste such as agriculture, forestry or even maintenance of green spaces the advancement of CBP systems represents a potentially effective and even beneficial waste management strategy other than composting.
References
Weimer J. Paul, Russell B. James, & Muck E. Richard. (2009). Lessons from the cow: What the ruminant animal can teach us about consolidated bioprocessing of cellulosic biomass. [Lessons from the cow: What the ruminant animal can teach us about consolidated bioprocessing of cellulosic biomass] Bioresource Technology, 100(21), 5323-5331.
Monday, October 5, 2009
Reusable vs. Disposable Cups
In his blog post entitled Reusable vs. Disposable Cups: Saving Money and Energy (July, 2009, http://greenresearch.com/2009/07/16/reusable-vs-disposable-cups-saving-money-and-energy), author David Schatsky discusses the environmental impacts of disposable cups (paper, plastic, polystyrene foam) versus reusable cups (glass, ceramic, higher grade reusable plastic). Schatsky focuses on the impact related to the energy involved in each type of cup. His blog post derives most of its information from one particular study. The study Schatsky cites is entitled Reusable and Disposable Cups: An Energy-Based Evaluation. It was performed by Martin B. Hocking, a chemist at the University of Victoria, and was published in the journal Environmental Management, Vol. 18, No. 6.
From findings in the study, Schatsky highlights many of the energy break-even ratios of the different cup types. For example, polystyrene foam cups require relatively little energy to manufacture, where as ceramic cups require much energy. Therefore, a ceramic cup needs to be reused many times before its energy requirement balances with the energy required to manufacture that number of singly-used foam cups. In this case, the break-even point is 1006 uses (Schatsky, 2009).
Hocking’s study uses a thorough set of equations for determining the total energy involved in all aspect of each cup’s life. These include extracting and processing the raw materials, manufacturing the cups, and washing the reusable varieties. The energy expenditure of each cup type is expressed as a value of kilojoules per gram. It is from these values, along with variables such as the number of uses before washing or disposing, that Hocking arrives at his break-even ratios. These ratios compose the majority of results from the study.
Schatsky accurately summarizes results from the study using data, without making any particularly strong claims that aren’t supported by such data. However, when discussing energy requirements for paper cups, he does use language that is overly strong and subjective. He twice refers to paper as being “an energy hog”. This description goes beyond the data provided in Hocking’s study, and stands out as very opinionated, in an article that is generally results-based.
Hocking performed a number of sensitivity tests in his study, calculating how changes in certain variables affect the break-even ratios. Schatsky does discuss these tests and their results in his article. For example, he notes that if energy in the washing process is reduced by 50%, the breakeven for reusable plastic versus polystyrene falls to 59 versus the 450 from standard energy requirements (Schatsky, 2009). Schatsky goes even further to note that energy efficiency in dish washing has improved since publication of the study, thus highlighting how this limiting variable would affect results if more current data were used to calculate washing energy.
There is one particular limiting factor in Hocking’s study, though, which Schatsky does not discuss in his article. Hocking’s method for determining energy requirements for the manufacture of disposable cups requires that this energy value be compared to the equivalent amount of electricity for washing reusable cups. Such a comparison requires values for the efficiency of electricity production in the area where the manufacturing and washing are done. Efficiency values vary from country to country. For example, Canada has an average electrical generating efficiency of 57.3%, compared to the US at 38% (Hocking, 1994). Values from other countries range from 33.0% to 99.6%. However, Hocking uses the efficiency value from Canada when calculating all energy requirements. Therefore, the actual requirements would vary depending on the country where the manufacture and washing occur.
References:
Schartsky, David, Reusable vs. Disposable Cups: Saving Money and Energy, 2009, http://greenresearch.com/2009/07/16/reusable-vs-disposable-cups-saving-money-and-energy.
Hocking, Martin, Reusable and Disposable Cups: An Energy-Based Evaluation, 1994, Environmental Management, Vol. 18, No. 6.
From findings in the study, Schatsky highlights many of the energy break-even ratios of the different cup types. For example, polystyrene foam cups require relatively little energy to manufacture, where as ceramic cups require much energy. Therefore, a ceramic cup needs to be reused many times before its energy requirement balances with the energy required to manufacture that number of singly-used foam cups. In this case, the break-even point is 1006 uses (Schatsky, 2009).
Hocking’s study uses a thorough set of equations for determining the total energy involved in all aspect of each cup’s life. These include extracting and processing the raw materials, manufacturing the cups, and washing the reusable varieties. The energy expenditure of each cup type is expressed as a value of kilojoules per gram. It is from these values, along with variables such as the number of uses before washing or disposing, that Hocking arrives at his break-even ratios. These ratios compose the majority of results from the study.
Schatsky accurately summarizes results from the study using data, without making any particularly strong claims that aren’t supported by such data. However, when discussing energy requirements for paper cups, he does use language that is overly strong and subjective. He twice refers to paper as being “an energy hog”. This description goes beyond the data provided in Hocking’s study, and stands out as very opinionated, in an article that is generally results-based.
Hocking performed a number of sensitivity tests in his study, calculating how changes in certain variables affect the break-even ratios. Schatsky does discuss these tests and their results in his article. For example, he notes that if energy in the washing process is reduced by 50%, the breakeven for reusable plastic versus polystyrene falls to 59 versus the 450 from standard energy requirements (Schatsky, 2009). Schatsky goes even further to note that energy efficiency in dish washing has improved since publication of the study, thus highlighting how this limiting variable would affect results if more current data were used to calculate washing energy.
There is one particular limiting factor in Hocking’s study, though, which Schatsky does not discuss in his article. Hocking’s method for determining energy requirements for the manufacture of disposable cups requires that this energy value be compared to the equivalent amount of electricity for washing reusable cups. Such a comparison requires values for the efficiency of electricity production in the area where the manufacturing and washing are done. Efficiency values vary from country to country. For example, Canada has an average electrical generating efficiency of 57.3%, compared to the US at 38% (Hocking, 1994). Values from other countries range from 33.0% to 99.6%. However, Hocking uses the efficiency value from Canada when calculating all energy requirements. Therefore, the actual requirements would vary depending on the country where the manufacture and washing occur.
References:
Schartsky, David, Reusable vs. Disposable Cups: Saving Money and Energy, 2009, http://greenresearch.com/2009/07/16/reusable-vs-disposable-cups-saving-money-and-energy.
Hocking, Martin, Reusable and Disposable Cups: An Energy-Based Evaluation, 1994, Environmental Management, Vol. 18, No. 6.
Sewage Leaching Into Oceans in Florida
When landfills and cess pits are located too close to any kind of body of water, many problems can arise. The fecal matter from the sewages and cess pits often leach into the soil, and if controlled properly, they do not pose much of a threat to the health of humans and aquatic organisms. However, in many cases, these sewage systems are not properly managed and controlled, and as the fecal matter leaches into the soil, it can get into ground water which evidently ends up in larger bodies of water. It is not the fecal matter itself which can be harmful, but the viruses and bacteria that inhabit the fecal matter. A category of viruses called enteric viruses are viruses that live in the intestinal tract (and therefore are plentiful in human waste) and they can cause infections and diseases in humans and other organisms. In a study performed by Erin Lipp, and doctoral student Carrie Futch from the University of Georgia, along with Dale Griffin of the U.S. Geological Survey in Tallahassee, coral reefs and water columns near Florida Keys was tested for the presence of these enteric viruses. The study is called “Analysis of multiple enteric viral targets as sewage markers in coral reefs” and it was performed during the years 2001, 2002, and 2003.
The secondary source that I found was an article from the Innovations Report entitled “Study finds contaminated water reaching Florida’s offshore keys” written by Sam Fahmy, which was reporting on the findings of the study authored by Lipp. There were many similarities between the secondary article and the primary journal article, but there were also a few things that I found that were reported differently in the secondary article. For one, the actual study is much more detailed in the explanation of the method they used to extract the enteric viruses from the samples and they explain their data a lot more thoroughly in the primary article. The secondary article did not give any real data at all, but just talked about the results and the conclusion taken from the study.
The study performed by the University of Georgia collected coral mucus and water samples and tested for enteric viruses present in those samples. They collected 100 coral and water samples throughout the Florida Keys national Marine Sanctuary and the Dry Tortugas and the study went on for three years. The article in which the results were reported also states that the study went on for three years, but the article did not mention how many samples were collected. It did say however that the samples were collected in five different sites. In the actual study, genetic material was extracted from the enteric viruses and was tested for to see whether they caused diseases in humans and it was found that they do. The secondary article reported this correctly as they stated that “Genetic material from enteric viruses, which cause disease in humans but are only found in infected human feces and urine, also were commonly found throughout the sampled area...” (Fahmy 2007).
A difference that I found between the two articles was that the secondary article described that common fecal indicator bacteria were analyzed, and these indicator fecal bacteria showed how much of the waste matter from the sewages and cess pits were leaking into the ground water. However this is a major difference from what the primary journal article reported, as they said that they analyzed for enteric viruses instead of indicator fecal bacteria because the enteric viruses show more clearly whether the reefs and the water have been contaminated than the indicator bacteria and viruses do. The study states that, “These viral based approaches have demonstrated susceptibility of near shore, offshore and outlying reefs to wastewater contamination when the traditional fecal indicator bacteria levels suggested ‘no evidence of contamination’” (Lipp 2007).
The original article also stated some restrictions that the secondary article failed to mention. The secondary source made it seem as though the study was now fully complete and the treatment was the only thing left to do, but the original article talked about how additional work would need to be done in order for the study to be truly complete. The next part of the study would be to determine whether another type of virus called adenovirus could be used as a marker of human sewage as well, but this cannot be done as of right now. The primary article claims that because RNA and DNA-based viruses are different enough, we cannot tell if adenovirus can be used as a marker. This is a limitation that the secondary article did not mention.
The primary and the secondary articles both stated the same conclusion, and that was that there were more enteric viruses found closer to shore and in areas where the populations were larger. This makes sense, since there are more people in the highly populated places and therefore more fecal matter that is leaching into the ground water and contaminating the coral reefs and the water. Also, both articles say that there were more enteric viruses found in the surface layers of the coral mucus than in the water columns which were also sampled. The original study discusses this in more detail however and they state that because the viruses are trapped in the coral mucus, they are protected from UV degradation and therefore are more plentiful than they are in the water columns. Although there were a few differences between the two sources, I believe that the secondary journal article had enough similarities to the primary study, that it is a fair representation of the study that was performed.
References
Fahmy, S. (2007) Study finds contaminated water reaching florida’s offshore keys. Innovations Report, 26 july 2007. http://www.innovations-report.com/html/reports/environment_sciences/report-87937.html. Accessed October 5, 2009.
Lipp, E., Futch, J., Griffin, D. (2007) Analysis of multiple enteric viral targets as sewage markers in coral reefs. Marine Pollution Bulletin. http://journals2.scholarsportal.info/tmp/9215686711381326070.pdf. Accessed October 5, 2009
The secondary source that I found was an article from the Innovations Report entitled “Study finds contaminated water reaching Florida’s offshore keys” written by Sam Fahmy, which was reporting on the findings of the study authored by Lipp. There were many similarities between the secondary article and the primary journal article, but there were also a few things that I found that were reported differently in the secondary article. For one, the actual study is much more detailed in the explanation of the method they used to extract the enteric viruses from the samples and they explain their data a lot more thoroughly in the primary article. The secondary article did not give any real data at all, but just talked about the results and the conclusion taken from the study.
The study performed by the University of Georgia collected coral mucus and water samples and tested for enteric viruses present in those samples. They collected 100 coral and water samples throughout the Florida Keys national Marine Sanctuary and the Dry Tortugas and the study went on for three years. The article in which the results were reported also states that the study went on for three years, but the article did not mention how many samples were collected. It did say however that the samples were collected in five different sites. In the actual study, genetic material was extracted from the enteric viruses and was tested for to see whether they caused diseases in humans and it was found that they do. The secondary article reported this correctly as they stated that “Genetic material from enteric viruses, which cause disease in humans but are only found in infected human feces and urine, also were commonly found throughout the sampled area...” (Fahmy 2007).
A difference that I found between the two articles was that the secondary article described that common fecal indicator bacteria were analyzed, and these indicator fecal bacteria showed how much of the waste matter from the sewages and cess pits were leaking into the ground water. However this is a major difference from what the primary journal article reported, as they said that they analyzed for enteric viruses instead of indicator fecal bacteria because the enteric viruses show more clearly whether the reefs and the water have been contaminated than the indicator bacteria and viruses do. The study states that, “These viral based approaches have demonstrated susceptibility of near shore, offshore and outlying reefs to wastewater contamination when the traditional fecal indicator bacteria levels suggested ‘no evidence of contamination’” (Lipp 2007).
The original article also stated some restrictions that the secondary article failed to mention. The secondary source made it seem as though the study was now fully complete and the treatment was the only thing left to do, but the original article talked about how additional work would need to be done in order for the study to be truly complete. The next part of the study would be to determine whether another type of virus called adenovirus could be used as a marker of human sewage as well, but this cannot be done as of right now. The primary article claims that because RNA and DNA-based viruses are different enough, we cannot tell if adenovirus can be used as a marker. This is a limitation that the secondary article did not mention.
The primary and the secondary articles both stated the same conclusion, and that was that there were more enteric viruses found closer to shore and in areas where the populations were larger. This makes sense, since there are more people in the highly populated places and therefore more fecal matter that is leaching into the ground water and contaminating the coral reefs and the water. Also, both articles say that there were more enteric viruses found in the surface layers of the coral mucus than in the water columns which were also sampled. The original study discusses this in more detail however and they state that because the viruses are trapped in the coral mucus, they are protected from UV degradation and therefore are more plentiful than they are in the water columns. Although there were a few differences between the two sources, I believe that the secondary journal article had enough similarities to the primary study, that it is a fair representation of the study that was performed.
References
Fahmy, S. (2007) Study finds contaminated water reaching florida’s offshore keys. Innovations Report, 26 july 2007. http://www.innovations-report.com/html/reports/environment_sciences/report-87937.html. Accessed October 5, 2009.
Lipp, E., Futch, J., Griffin, D. (2007) Analysis of multiple enteric viral targets as sewage markers in coral reefs. Marine Pollution Bulletin. http://journals2.scholarsportal.info/tmp/9215686711381326070.pdf. Accessed October 5, 2009
American E-waste in Peru
It is hard to deny that western society’s dependence on new and improved personal computers (PCs) is significantly high, but when considering this statement, one simple question comes to mind. Where do all the old computers go? As time and technology evolves, computer lifespan is actually decreasing, creating more electronic waste (e-waste) than there is room for. The United States have come up with their own solution on how to manage this “junk”; Peru. By exporting their e-waste to the developing South American country, the states easily resolve environmental issues concerned with recycling these unwanted PCs, the majority of these issues being the release of toxic emissions.
Although the problem does not technically belong to the US anymore, researchers continue to question exactly how many of these exported PCs are reused in Peru. They also show concern as to whether the Peruvian government keeps track of the number of computers imported, and where these imports actually end up. In June 2009, Ramzy Kahhat and Eric Williams published a study entitled “Product or Waste? Importation and End-of-Life Processing of Computers in Peru”, which gave answers, including evidence, to these mentioned questions.
The study, which was published in the Environmental Science and Technology journal, is considered the most comprehensive inquiry of computer reuse in a developing country (Betts, 2009). It determined from Peruvian records that 57-76% of the computers imported during the years 2003 to 2007 were directly from the United States (Betts, 2009). It also revealed that at least 85% of unwanted PCs imported to Peru are reused, instead of being directly recycled (Betts 2009). This evidence, along with other, ultimately suggested that the idea that e-waste is exported to Peru mainly to dump unusable junk is inaccurate (Betts, 2009).
In contrast to this inquiry, where researchers provide an in depth look at imports of American PCs in Peru, there is also an article entitled “E-waste reuse may be more persuasive than previously thought” which refers to and summarizes the key objectives, ideas, and conclusions behind the study. The article, which was written by Kellyn Betts in 2009, contains several of the same pieces of information as the original study does, but in a varying manner. The main differences noted between the two sources are the amount of detail given about how the study was conducted, the tables, graphs, and diagrams used to solidify the claim, and the magnitude at which the limitations were discussed.
First of all, the differences with regards to the details of the study can be seen in the introductions. Kahhat and Williams initially begin their paper with a paragraph on what their study entails and describe how they analysed government data to eventually reach their conclusion. They also give mention to background information that was taken into consideration. They then proceed with an elaborate introduction which firstly explains definitions and continues on to identify the three main questions behind the study. Whereas on the other hand, Betts begins her article with a concise description of the study, an outline of the results that were determined, and a brief biography of the lead author and his associate. As well as having a more detailed introduction, the original study also includes materials and methods that were used as well as relevant information such as the computer recycling system in Lima (the capital of Peru). Betts’ article lacks in this area because the primary purpose of her piece is to inform the general public of the study that was made. This alludes to the idea that for the readers to understand the basic logistics of the experiment, only a summary of the observations and findings are necessary.
Not only does Kahhat and William’s work have more detail in their words, but they also give figures that visually demonstrate the data they observed and analysed throughout the study. For example, they include a graph depicting the importation of used and new non-mobile and mobile personal computers to Peru, as well as a table projecting the main paths followed by computer parts and materials. In Betts’ article, there are no examples of concrete data that are used as evidence. This leads to the idea that the primary source has a stronger claim since the authors gave actual proof, which in return creates more solid arguments to back up their conclusion. When reading the secondary source, the audience must trust that the information they are given is credible and that it is indeed coming from a reliable primary source.
Lastly, in the original article, there is an entire section devoted to a discussion of the limitations that were involved. In this fragment, the author states:
“There could be illegal trade, however, the extent and character of which are as yet unknown. The nature of the used computer trade in other countries such as China and India is also still uncertain. We have shown how to use official trade statistics, when available, to characterize if trade is reuse versus recycling oriented. More work is needed both to learn from official statistics from other countries as well as find new ways to characterize legal trade.” (Kahhat, Williams, 2009)
This quote implies that the researchers have acknowledged the limits of their conclusion, while stating an improvement that is necessary to guarantee their findings. This limit is also mentioned in the secondary source when Betts quotes that the researchers feel that their paper provides “compelling evidence that much of the used computer exports to Peru is driven by reuse, we don’t know if this is the case for other countries – the situation could be different” (Kahhat, Williams, 2009). Although Betts recognizes this limit, she only briefly summarizes it, as oppose to explaining it to the same extent as it was originally in the primary source.
Both sources are relevant to the needs and interests of their target audiences. The study conducted by Kahhat and Williams provides an in depth explanation and analysis of how and why they concluded that the assumed image of the United State’s exportation of unwanted PCs is incorrect. The researchers used detailed descriptions, concrete data to strengthen their claim, and a discussion of limitations to educate their specific readers on their study, where as Betts used informative summarizing techniques to give an overview of the study to her intended readers.
References
Betts, K. (2009) E-waste reuse may be more pervasive than previously thought. Environmental Science & Technology, volume 43, No. 18, 29 July 2009. http://pubs.acs.org/doi/pdfplus/10.1021/es902021q. Accessed 4 Sunday Sept 2009.
Kahhat R., Williams, K. (2009) Product or Waste? Importation and End-of-Life Processing of Computers in Peru. Environmental Science & Technology, volume 43, No. 15, 2 June 2009. http://pubs.acs.org/doi/pdf/10.1021/es8035835. Accessed 4 Sunday Sept 2009.
Although the problem does not technically belong to the US anymore, researchers continue to question exactly how many of these exported PCs are reused in Peru. They also show concern as to whether the Peruvian government keeps track of the number of computers imported, and where these imports actually end up. In June 2009, Ramzy Kahhat and Eric Williams published a study entitled “Product or Waste? Importation and End-of-Life Processing of Computers in Peru”, which gave answers, including evidence, to these mentioned questions.
The study, which was published in the Environmental Science and Technology journal, is considered the most comprehensive inquiry of computer reuse in a developing country (Betts, 2009). It determined from Peruvian records that 57-76% of the computers imported during the years 2003 to 2007 were directly from the United States (Betts, 2009). It also revealed that at least 85% of unwanted PCs imported to Peru are reused, instead of being directly recycled (Betts 2009). This evidence, along with other, ultimately suggested that the idea that e-waste is exported to Peru mainly to dump unusable junk is inaccurate (Betts, 2009).
In contrast to this inquiry, where researchers provide an in depth look at imports of American PCs in Peru, there is also an article entitled “E-waste reuse may be more persuasive than previously thought” which refers to and summarizes the key objectives, ideas, and conclusions behind the study. The article, which was written by Kellyn Betts in 2009, contains several of the same pieces of information as the original study does, but in a varying manner. The main differences noted between the two sources are the amount of detail given about how the study was conducted, the tables, graphs, and diagrams used to solidify the claim, and the magnitude at which the limitations were discussed.
First of all, the differences with regards to the details of the study can be seen in the introductions. Kahhat and Williams initially begin their paper with a paragraph on what their study entails and describe how they analysed government data to eventually reach their conclusion. They also give mention to background information that was taken into consideration. They then proceed with an elaborate introduction which firstly explains definitions and continues on to identify the three main questions behind the study. Whereas on the other hand, Betts begins her article with a concise description of the study, an outline of the results that were determined, and a brief biography of the lead author and his associate. As well as having a more detailed introduction, the original study also includes materials and methods that were used as well as relevant information such as the computer recycling system in Lima (the capital of Peru). Betts’ article lacks in this area because the primary purpose of her piece is to inform the general public of the study that was made. This alludes to the idea that for the readers to understand the basic logistics of the experiment, only a summary of the observations and findings are necessary.
Not only does Kahhat and William’s work have more detail in their words, but they also give figures that visually demonstrate the data they observed and analysed throughout the study. For example, they include a graph depicting the importation of used and new non-mobile and mobile personal computers to Peru, as well as a table projecting the main paths followed by computer parts and materials. In Betts’ article, there are no examples of concrete data that are used as evidence. This leads to the idea that the primary source has a stronger claim since the authors gave actual proof, which in return creates more solid arguments to back up their conclusion. When reading the secondary source, the audience must trust that the information they are given is credible and that it is indeed coming from a reliable primary source.
Lastly, in the original article, there is an entire section devoted to a discussion of the limitations that were involved. In this fragment, the author states:
“There could be illegal trade, however, the extent and character of which are as yet unknown. The nature of the used computer trade in other countries such as China and India is also still uncertain. We have shown how to use official trade statistics, when available, to characterize if trade is reuse versus recycling oriented. More work is needed both to learn from official statistics from other countries as well as find new ways to characterize legal trade.” (Kahhat, Williams, 2009)
This quote implies that the researchers have acknowledged the limits of their conclusion, while stating an improvement that is necessary to guarantee their findings. This limit is also mentioned in the secondary source when Betts quotes that the researchers feel that their paper provides “compelling evidence that much of the used computer exports to Peru is driven by reuse, we don’t know if this is the case for other countries – the situation could be different” (Kahhat, Williams, 2009). Although Betts recognizes this limit, she only briefly summarizes it, as oppose to explaining it to the same extent as it was originally in the primary source.
Both sources are relevant to the needs and interests of their target audiences. The study conducted by Kahhat and Williams provides an in depth explanation and analysis of how and why they concluded that the assumed image of the United State’s exportation of unwanted PCs is incorrect. The researchers used detailed descriptions, concrete data to strengthen their claim, and a discussion of limitations to educate their specific readers on their study, where as Betts used informative summarizing techniques to give an overview of the study to her intended readers.
References
Betts, K. (2009) E-waste reuse may be more pervasive than previously thought. Environmental Science & Technology, volume 43, No. 18, 29 July 2009. http://pubs.acs.org/doi/pdfplus/10.1021/es902021q. Accessed 4 Sunday Sept 2009.
Kahhat R., Williams, K. (2009) Product or Waste? Importation and End-of-Life Processing of Computers in Peru. Environmental Science & Technology, volume 43, No. 15, 2 June 2009. http://pubs.acs.org/doi/pdf/10.1021/es8035835. Accessed 4 Sunday Sept 2009.
Sunday, October 4, 2009
Carbon dioxide deep sea storage
The issue of managing increasing levels of carbon dioxide waste is a hot topic nowadays. Many solutions have been proposed, one of the foremost is to store liquid carbon dioxide gas in deposits under the ocean floor. I found two sources of information on the topic, one primary and the other secondary. The primary source entails the proposition, “Carbon Dioxide Sequestration in Deep-Sea Basalt” by David S. Goldberg, Taro Takahashi and Angela L. Sagle. They’re findings were reported in the Seattle Times, “Storing Carbon Dioxide Under NW Seafloor Proposed” by Sandi Doughton.
There are a number of differences between the two sources, the most prominent of which involves the amount of information being displayed. A large number of factors could play into this, for example a newspaper is only allocated a certain amount of room, while the published work of researchers would need the small details and statistics to prove their arguments thoroughly.
The article, “Storing Carbon Dioxide under NW Seafloor Proposed” by Doughton also lacks an argument. Doughtan actually seems reluctant to make a concrete statement on the topic, “scientists say a partial solution to global warming,” (Doughton 2008) The author is careful not to be overly optimistic, “Researchers envision a system” (Doughton 2008), I admire how the author simply reports and does not offer an opinion allowing the reader to make their own informed opinion.
Goldberg et al. however are more dynamic in they’re arguments. Unlike the newspaper article they aim to advertise and gain support for their research. They thoroughly back all claims with a number of statistics, “geological storage of industrial CO2 emissions can contribute significantly to achieving a stable solution,” (Goldberg et al. 2008) They also cite a number of different researchers to support their claim, “Matter et al. (25) conducted a small-scale injection experiment,” (Goldberg et al. 2008). They include diagrams on how the process would run as well as.
The newspaper article lacks all the statistics that the primary source provides, “Bulk permeability estimates in the shallow basement range from 10−9 to 10−13 m2” (Goldberg et al 2008). Instead it focuses more on informing a regular audience, and a long winded detailed account would not sell as many copies as a concise article that tells the reader what they want to know in a few paragraphs. The first paragraph itself summarizes easily what the rest is about, “Deep volcanic rocks could serve as a kind of storage locker for carbon dioxide, trapping the greenhouse gas under great pressure with virtually no chance of leaking back into the atmosphere,” (Doughton 2008). This format allows the reader to stop any time without having to search the rest of the article for key points. Newspaper articles are also designed in a way that can easily be edited to fit what ever space has been given, i.e. if an article has to be cut short it can be done with the deletion of a few paragraphs instead of a complete revision.
I believe that the general public simply has no time to sit and read every research publication that is out there. A newspaper can neatly sum up the information in a way the reader can easily decipher. However I only find that some articles contain a large bias and argument on the topic, to find an article without bias is harder, yet easier for the readers to judge information for themselves. The paper by Goldberg et al. also tries somewhat to appeal to the general public; they do this by adding diagrams and pictures
Resources:
Doughton, Sandi. (2008) Storing Carbon Dioxide Under NW Seafloor Proposed. Seattle Times. July 14 2008. Accessed October 1, 2008 from: http://seattletimes.nwsource.com/html/localnews/2008050976_webcarbonstorage14m.html
Goldberg, David S. et al. (2008) Carbon Dioxide Sequestration in Deep-Sea Basalt. Proceedings of the National Academy of Sciences. May 7, 2008. Accessed October 1, 2009 from : http://www.pnas.org/content/105/29/9920.full?sid=688f33eb-ce02-4893-8816-7ee1b03c43b7se
Avian Flu in Landfills?
Nature can be seen as a complex system of checks and balance and it is the biotic factors of life such as lack of food or predation that keep populations in check in order to ensure that this delicate balance is met. Humans have long tried to defy this fact of nature by building immense civilizations where food is plentiful and predators are no longer an issue, but despite our best attempts we cannot escape the ever present threat of disease. Throughout the history of human civilization, humans have been plagued by disease. In Europe during the Middle Ages it was the bubonic plague,with other notable examples such as The Spanish Flu of 1918and the cholera outbreaks during the 19th century. Even the briefest look through history reveals a disturbing trend of pestilence and fear. Ironically, the success of these plagues can be directly attributed to conditions that arose out of living in densely populated settlements, the biggest of which is poor sanitation. In the 21st century it seems we have learned from the past, and as a result we have much improved sanitation practises, but the modern day epidemics are arising from a very different source; agriculture. With the advent of the industrial revolution convenience and efficiency has dominated the way in which livestock and poultry farms are operated. With thousands of animals being crowded into cramped spaces and being fed growth hormones the farms of today resemble factories more than farms. With all these immunocompromised animals being cramped together in small confined spaces it’s really not much of a surprise that in these conditions it only takes one animal to get sick to start an epidemic. Avian influenza virus and the more recent H1N1 are the two pandemic potentials that continue to dominate the headlines.
To date hundreds of millions of birds have been killed by the Avian influenza virus or as a result of efforts to contain the virus (Bartelt-Hunt 2009). One of the issues that arise from this containment method is the disposal of a large number of carcasses. Currently, there are a number of different disposal methods that exist, but the three that are most recommended/economical for farmers are; on site burial, compositing or off site burial (landfills)(Bartelt –Hunt 2009). For disposal of large die-offs, off site burial at municipal solid waste landfills are a convenient option due to accessibility and capacity. However, a new study has revealed that even after disposal the virus can remain active in the dead host for up to two years. The study which was conducted by Bartelt-Hunt and colleagues from the University of Nebraska and was published in Environmental Science & Technology on April 30 2009. This study was unique in that it was the first one which set out to determine how long AIV remained infectious in leachate from landfills. The study compared how long AIV remained active in leachate versus water based on altering temperature, pH and conductivity (heavy metals). The results of the experiment showed that AIV had the potential to persist for up to two years at a low temperatures (4oC) and a neutral pH in both water and leachate. But, in leachate with non ideal conditions the AIV virus became inactive at either the same or two times faster than in water. This study was referred to in an article entitled Bird flu Survives in Landfills by Emily Sohn in Discovery News. The main differences between the two sources are:
1. Details of the study
2. Strength of claims
3. Extent of discussion of limitations
4. Language used/target audience
In the primary journal article all the details pertaining to the study such as materials, methods and raw experimental data are provided. Since the source is primary the extent of detail regarding the study needs to be provided in order for credibility of the experiment to be verified. However in the secondary source, some details regarding the basics of the experiment are provided but not to the extent provided in the primary source. One of the crucial reasons for the contrast in detail provided is also related to the differences in target audiences. The primary source article is indented for peers and other researchers as demonstrated by the language used and the extent of the detail. The secondary source is a news article that is directed at the public, as a result the language is much simpler and extensive detail of the study is omitted purely for the reason of making the article more comprehendible to individuals who do not have a research background. Another key difference is the strength of the claims made by both sources. In the primary article data was provided and conclusions were qualified based on the results. In contrast, the secondary source quoted the conclusions as fact without highlighting any uncertainty.
“AIV inactivation rates calculated in this study yield theoretical persistence times ranging from approximately 30 to >600 days (based on initial titer of 105 tissue culture infection dose50 (TCID50)). This indicates that AIV could remain infectious both during and after waste placement”(Bartelt-Hunt 2009).
The study also mentions that the AIV became inactive at the same or at a rate 2 times faster than that in water. In contrast the secondary article makes much more direct claims from the results of the study, the key difference again in the wording.
“After 60 days, the researchers were able to estimate how long the virus would remain infectious based on how quickly it was breaking down. At colder temperatures and neutral pH levels, the researchers reported in Environmental Science & Technology, the virus was likely to survive the longest -- sometimes for up to nearly two years. (Sohn 2009)”
Although no data is provided the same conclusion is made, but with more certainty. In addition the article does not mention the differing rates of inactivation between the leachate and water. Another key difference is the extent of the detail pertaining specifically to the limitations of the study.
In the primary source multiple acknowledgments are made regarding the limitations of the study such as, the exclusion of solid waste or microbials from the leachate and how that impacts virus survival. In contrast, in the secondary source the extent of the discussion of limitations is very simple. The article quotes David Stalknecht an epidemiologist who simply states “The lab experiment was a simplified version of what happens inside landfills, he said. In the real world, plenty of factors are likely to deactivate viruses more quickly”. (Sohn 2009)
The main reason for these differences is the target audiences: The primary source is intended for researchers and this is reflected in the language and extent of detail regarding the study. The secondary source is intended as a news article for the general public, therefore the language is much simpler and only final results of the study are included without any discussion of the study limitations.
References
Bartelt-Hunt, S.(2009) Survival of the Avian Influenza Virus (H6N2) After Land Disposal. Enviroment Science & Technology,43: 4063-4067. 30 April 2009. Retrieved October 1 2009 from, http://pubs.acs.org.subzero.lib.uoguelph.ca/doi/full/10.1021/es900370x
Sohn, E. (2009) Bird Flu Survives in Landfills. Discovery News, June 9 2009. Retrieved October 1 2009 from http://dsc.discovery.com/news/2009/06/09/bird-flu-landfills.html
To date hundreds of millions of birds have been killed by the Avian influenza virus or as a result of efforts to contain the virus (Bartelt-Hunt 2009). One of the issues that arise from this containment method is the disposal of a large number of carcasses. Currently, there are a number of different disposal methods that exist, but the three that are most recommended/economical for farmers are; on site burial, compositing or off site burial (landfills)(Bartelt –Hunt 2009). For disposal of large die-offs, off site burial at municipal solid waste landfills are a convenient option due to accessibility and capacity. However, a new study has revealed that even after disposal the virus can remain active in the dead host for up to two years. The study which was conducted by Bartelt-Hunt and colleagues from the University of Nebraska and was published in Environmental Science & Technology on April 30 2009. This study was unique in that it was the first one which set out to determine how long AIV remained infectious in leachate from landfills. The study compared how long AIV remained active in leachate versus water based on altering temperature, pH and conductivity (heavy metals). The results of the experiment showed that AIV had the potential to persist for up to two years at a low temperatures (4oC) and a neutral pH in both water and leachate. But, in leachate with non ideal conditions the AIV virus became inactive at either the same or two times faster than in water. This study was referred to in an article entitled Bird flu Survives in Landfills by Emily Sohn in Discovery News. The main differences between the two sources are:
1. Details of the study
2. Strength of claims
3. Extent of discussion of limitations
4. Language used/target audience
In the primary journal article all the details pertaining to the study such as materials, methods and raw experimental data are provided. Since the source is primary the extent of detail regarding the study needs to be provided in order for credibility of the experiment to be verified. However in the secondary source, some details regarding the basics of the experiment are provided but not to the extent provided in the primary source. One of the crucial reasons for the contrast in detail provided is also related to the differences in target audiences. The primary source article is indented for peers and other researchers as demonstrated by the language used and the extent of the detail. The secondary source is a news article that is directed at the public, as a result the language is much simpler and extensive detail of the study is omitted purely for the reason of making the article more comprehendible to individuals who do not have a research background. Another key difference is the strength of the claims made by both sources. In the primary article data was provided and conclusions were qualified based on the results. In contrast, the secondary source quoted the conclusions as fact without highlighting any uncertainty.
“AIV inactivation rates calculated in this study yield theoretical persistence times ranging from approximately 30 to >600 days (based on initial titer of 105 tissue culture infection dose50 (TCID50)). This indicates that AIV could remain infectious both during and after waste placement”(Bartelt-Hunt 2009).
The study also mentions that the AIV became inactive at the same or at a rate 2 times faster than that in water. In contrast the secondary article makes much more direct claims from the results of the study, the key difference again in the wording.
“After 60 days, the researchers were able to estimate how long the virus would remain infectious based on how quickly it was breaking down. At colder temperatures and neutral pH levels, the researchers reported in Environmental Science & Technology, the virus was likely to survive the longest -- sometimes for up to nearly two years. (Sohn 2009)”
Although no data is provided the same conclusion is made, but with more certainty. In addition the article does not mention the differing rates of inactivation between the leachate and water. Another key difference is the extent of the detail pertaining specifically to the limitations of the study.
In the primary source multiple acknowledgments are made regarding the limitations of the study such as, the exclusion of solid waste or microbials from the leachate and how that impacts virus survival. In contrast, in the secondary source the extent of the discussion of limitations is very simple. The article quotes David Stalknecht an epidemiologist who simply states “The lab experiment was a simplified version of what happens inside landfills, he said. In the real world, plenty of factors are likely to deactivate viruses more quickly”. (Sohn 2009)
The main reason for these differences is the target audiences: The primary source is intended for researchers and this is reflected in the language and extent of detail regarding the study. The secondary source is intended as a news article for the general public, therefore the language is much simpler and only final results of the study are included without any discussion of the study limitations.
References
Bartelt-Hunt, S.(2009) Survival of the Avian Influenza Virus (H6N2) After Land Disposal. Enviroment Science & Technology,43: 4063-4067. 30 April 2009. Retrieved October 1 2009 from, http://pubs.acs.org.subzero.lib.uoguelph.ca/doi/full/10.1021/es900370x
Sohn, E. (2009) Bird Flu Survives in Landfills. Discovery News, June 9 2009. Retrieved October 1 2009 from http://dsc.discovery.com/news/2009/06/09/bird-flu-landfills.html
Subscribe to:
Posts (Atom)
Posts
