False Positives In Presumptive Blood Testing Biology Essay

False Positives In Presumptive Blood Testing Biology Essay Blood is a fluid medium that is found within the cardiovascular system-which comprises of the heart and blood vessels (Jackson and Jackson 2008). It consists of 55% blood plasma and 45% cellular material (Jackson and Jackson 2008). Blood plasma consists of dissolved materials such as antibodies, hormones, waste products and nutrients, whereas the cellular material consists of erythrocytes (red blood cells), leucocytes (white blood cells) and thrombocytes (platelets) (Jackson and Jackson 2008). Blood is transported through the body by the pumping action of the heart. It has numerous functions including (Jackson and Jackson 2008): Acting as an internal transport system-including the removal of waste products for excretion and moving nutrients for metabolism. Maintaining body temperature. Defending against infection. Protecting the body from effects of injury. Blood is one of main sources of DNA found at crime scenes, and is crucially important in establishing a link between a suspect and a victim of a crime (Jackson and Jackson, 2008). To detect the presence of blood at a crime scene, a presumptive test is used. These can, however, only detect whether a substance is blood and cannot distinguish between human and animal blood-a serological test is needed to do this. The Erythrocytes (red blood cells) are the most common type of blood cell and contain haemoglobin (Jackson and Jackson 2008). They contain haemoglobin- a protein containing iron. Haemoglobin is responsible for the carriage of oxygen, and it is this property that presumptive blood tests are based on. Most of the presumptive tests rely on the ability of haemoglobin to catalyse the oxidation of a reagent, normally hydrogen peroxide (H2O2 (aq)) (Jackson and Jackson 2008). The result of oxidation normally produces a colour change in the presumptive test. Tiny amounts of blood present as a scene can be detecting using a colour change test. Some old and dried stains look similar in appearance to blood which can lead to a scenes of crime officer conducting a presumptive test. Other substances that could have contaminated suspected blood or other substances on their own at a scene could lead to a presumptive blood test incorrectly showing a positive result for blood. This is known as a false positive. Once a stain has been determined as blood, then two processes must be completed. The first is to interpret any bloodstain patterns, so that a reconstruction of events can be established (Langford et al 2005). Secondly, bloodstains must then be recovered for further analysis (Langford et al 2005). Recovery of bloodstains varies according to whether the stain is wet or dry. Once recovered, the blood can then be sent to a Forensic Science Service laboratory, where it will be initially tested to ascertain whether it is human or animal blood. To do this a serological test will be conducted, which involves identifying the presence of proteins specific to humans and analysing for DNA sequences specific to humans (Jackson and Jackson 2008). The blood will then be used for DNA profiling, which will hopefully establish whether the blood belongs to the suspect or the victim. I.II Aims and Objectives The aim of my project is to create a definitive list of false positives for four different presumptive blood tests. Within this aim I have six objectives to complete: To compare the false positives of four different presumptive tests. To test substances that are known false positives- as reported by other authors. To test unknown substances allied to those already known. To record the time taken for a substance to react with a presumptive test. To photograph the results of from each substance. To create a definitive list of false positives for each presumptive test. I am going to compare four different presumptive tests, as some tests are more practical to use in some situations than others. Consequently, analysing more than one test will allow a wider range of results. I shall also be testing known false positives as reported by other authors, as it is important to show how the presumptive tests react. Unknown substances allied to those that are known will then be tested to see whether similar substances react alike. This will then allow me to establish whether an unknown substance has reacted or not, as I can compare the reaction times and colour changes from both the known and unknown substances. It is important to record the time taken for a substance to react with a presumptive test, as blood should show a result straight away. An unobvious result that takes time to develop could indicate that the substance being tested is a false positive. Photographing results will allow me to document the differences in the colour change in each reaction with each substance. I feel that it is important to create a definitive list of false positives as it can reduce the risk of using valuable resources at a crime scene. For example, if a scenes of crime officer is informed that a possible blood stain has been contaminated with horseradish (a known false positive), then they can use a presumptive test for blood that is not known to produce a false positive with horseradish. If the result is positive for blood, then serological tests for blood can be carried out. Overall, I hope that this project will aid the work of a scenes of crime officer to choose the correct presumptive test to use in different situations-minimising time spent and resources used. Chapter II. Literature Review II.I Background Information The scientific analysis of blood was initially mentioned in 13th century Chinese texts, but it was Karl Landsteiner who discovered the modern science of blood typing, which categorises different types of blood into the ABO blood typing system (White 2010). In 1901 it was reported that blood could be determined in two week old serum stains on linen, and by 1902 the four blood types A, B, O and AB had been discovered (White 2010). This system is based on types of antigen on the red blood cells membrane. An antigen is a protein molecule capable of binding on to an antibody (Erzinà §lioglu 2004). The ABO system uses two antigens which are known as A and B; and the four blood groups are determined according to this system (Erzinà §lioglu 2004). People that have the blood group A have the A antigen, those that are group B have the B antigen; those in the AB category have both antigens and those who belong to the O group have neither antigen (Erzinà §lioglu 2004). A persons blood contai ns the opposite group of corresponding antibodies, so people with blood group A have b antibodies, people with blood group B have a antibodies, those with blood group AB have neither a or b antibodies and those with blood group O have both a and b antibodies (Erzinà §lioglu 2004). If the wrong antibodies are introduced into the wrong blood group then death can be a result due to the red cells clumping together. The first suspect to have been convicted largely on the basis of DNA analysis of blood samples was found guilty at Leicester Crown Court on 22nd January 1988 (White 2010). This case marks an important milestone, and DNA technology has become commonplace in forensic laboratories and is now instrumental in establishing both guilt and innocence in court cases (White 2010). II.II Physical Properties of Blood Blood constitutes about 7.7% of the body weight of a person (White 2010). This equates to 5-6 litres in males and 4-5 litres in females (Tortora and Anagnostakos 1987). Viscosity is resistance to flow, which in fluids is compared to water which has a viscosity of 1. (Bevel and Gardner 2002). Blood viscosity usually ranges between 4.4 and 4.7 (Tortora and Anagnostakos 1987). Blood also has a higher specific gravity (density) than water, which is the weight of a substance relative to the weight of an equal volume of water (James and Nordby 2005). Blood is a fluid that circulates throughout the body by way of the heart, arteries, veins and capillaries-known as the circulatory system (James and Nordby 2005). A primary function of blood is to transport oxygen, electrolytes, nourishment, hormones, vitamins and antibodies to tissues and to transport waste products from tissues to the excretory organs (James and Nordby 2005). Tortora and Anagnostakos (1987) (in Bevel and Gardner 2002) say that when 4-6 litres of blood is present in the circulatory system, it is distributed as follows: Figure 1- Blood Distribution in the Circulatory System (Tortora and Anagnostakos 1987) As a medium, blood is composed of 55% plasma and 45% cells (White 2010). A single drop or large volume of blood is held together by strong cohesive molecular forces that produce a surface tension (James and Nordby 2005). Surface tension is defined as the force that pulls the surface molecules of a liquid toward its interior, decreasing the surface area and causing the liquid to resist penetration (James and Nordby 2005). Bevel and Gardner (2002) state that plasma is the pale yellow fluid component of blood, which is broken down by volume into 91% water, 8% protein, 1% organic acids and 1% salts. Fibrinogen is one of the proteins, and this plays an important role in the clotting of blood (Bevel and Gardner 2002). Blood serum is blood plasma minus its protein content (Jackson and Jackson 2008). The cellular component of blood consists of erythrocytes (red blood cells), leukocytes (white blood cells) and thrombocytes (platelets) (Bevel and Gardner 2002). Red blood cells are heavier than plasma, which can be seen in bodies as lividity-which is where red cells settle to the lowest extremity of a body after death (Chmiel and Walitza 1980). http://people.eku.edu/ritchisong/301images/Red_White_Blood_cells.jpg Figure 2- A red blood cell, platelet and white blood cell (University of Eastern Kentucky 2010). There are roughly 4.8 to 5.4 million red blood cells per cubic millimetre of blood (Tortora and Anagnostakos 1987). They are bioconcaved discs in shape. The main role of the red blood cells is to transport oxygen from the lungs via the arterial system and return carbon dioxide to the lungs for expiration via the venous system (James and Nordby 2005). Red blood cells contain haemoglobin which is a red pigment that gives blood its colour (Bevel and Gardner 2002). Haemoglobin is composed of globin, which is made up of four folded polypeptide chains, and four haem groups that join with iron (University of Eastern Kentucky 2010). http://www.ul.ie/~childsp/CinA/Issue64/Images/TOC36_2.gif Figure 3- Haemoglobin, containing four haem groups (University of Limerick, 2010). As the oxygen content increases in the blood, the bright red pigment of the haemoglobin also increases (Bevel and Gardner 2002). A red blood cell does not contain a nucleus. Red blood cells are expressed as a percentage of the packed (red) cell volume (PCV), also known as the haematocrit (Wonder 2001). Nelson and Rodak (1983) state that the haematocrit in humans is variable between individuals. Haematocrit Possible people with range of haematocrit 15-29% Chronic alcoholics or drug abusers, steroid abusers, women after traumatic child birth or illegal abortion, malnourished homeless, elderly. 30-48% Normal range for nontraumatic venipuncture (blood drawn in a clinic or hospital) samples. 49-75% Dehydrated individuals, people in shock, those living at high altitude, impending and active heart attack victims, newborn babies, people suffering from hypothermia, and people after extreme exercise. Table 1- Table to show the range of haematocrit ratios (Wonder 2001). White blood cells act to fight infections, destroy old cellular material and to destroy other invading microbes (Bevel and Gardner 2002). White blood cells can be further subdivided into phagocytes which are responsible for the capture and ingestion and foreign substances, and lymphocytes- which are responsible for the production of antibodies (Jackson and Jackson 2008). They make up less than 1% of the cellular component of blood, which equates to 5000 to 9000 white blood cells per cubic millimetre (Tortora and Anagnostakos 1987). The nuclei of white blood cells are the source of DNA in the blood (James and Nordby 2005). The other part of the cellular component of blood is the platelets. Like red blood cells, platelets also lack a nucleus (Bevel and Gardner 2002). Bevel and Gardner (2002) say that there are generally about 250,000 to 400,000 platelets per cubic millimetre of blood. Platelets are major components of the clotting mechanism of blood, and this is their primary function (James and Nordby 2005). Platelets have irregular shapes and are normally quite small, however when they encounter a damaged blood vessel they increase their size and their shapes changes (Bevel and Gardner 2002). They also become sticky and adhere to surrounding fibres in the vessel wall, which results in the accumulation of platelets called the platelet plug (Bevel and Gardner 2002). II.III Blood at a Crime Scene Blood is normally found at a crime scene due to a person sustaining an injury either by accident or on purpose. When a breach in the circulatory system occurs- due to an injury- the body reacts in different ways to control the loss of blood (Bevel and Gardner 2002). Initially the vascular spasm occurs, which is which the smooth vessels in the blood vessel wall contract to decrease the size of the vessel, which reduces the flow of blood through it (Bevel and Gardner 2002). Tortora and Anagnostakos (1987) say that this reduces blood loss for up to 30 minutes following injury, which gives time for the other blood loss mechanisms to engage. The platelet plug then follows which reduces, if not stops, the blood loss (Bevel and Gardner 2002). The final step is coagulation, or clotting. This is what is normally seen at crime scenes, where the clotted mass of fibrin fibres and blood cells is surrounded by blood serum (Bevel and Gardner 2002). There are three types of bleeding that can occur from damage to blood vessels (BUPA 2009): Arterial Bleeding Venous Bleeding Capillary Bleeding. Arterial bleeding usually is spurting bright red blood, due to the blood having come from the heart and lungs-so it is oxygen rich (Walter et al 2004). The pumping action of the heart adds rhythmic surges to move blood vessels away from the heart (Wonder 2001). It is the most serious type of bleeding, and the most difficult to control due to the blood in the arteries being under pressure from the heart (Walter et al 2004). Arterial wounds results in volume stains (Wonder 2001). Loss from the carotid artery or the aorta can rapidly lead to death (Wonder 2001). Examples of arterial injuries, and how they may occur are listed in Table 2. Artery Location Probable Occurrence Facial Mouth/lips Beating Temporal Head/temples Gunshot, Crushing Carotid Neck, front throat Stab wound, Gunshot, Decapitation Subclavian Under collar bone Gunshot, Crushing Aorta Chest Gunshot, Stab wound Brachial Arm/elbow Bone break Radial Wrist Slit wrists, Bone Break, Stab wound Femoral Groin Gunshot, Stab wound Tibial Ankle Bone Break, Crushing Deltoid Upper arm muscle Stab wound Table 2- Areas and actions that may involve arterial damage (Wonder 2001) External venous bleeding is normally as a result of wounding, as veins are closer to the skin than arteries (Walter et al 2004). It results in the steady flow of dark red (almost brown) blood, and is darker than arterial blood as it has released oxygen to the tissues in the body and is flowing back to the heart and lungs for more oxygen (Walter et al 2004). Capillary wounding is common in minor wounds as capillaries are very small vessels that are under very little pressure with a low volume of blood (Walter et al 2004). Capillary bleeding results in the oozing of either bright or dark red blood, which will normally stop on its own (Walter et al 2004). As well as the three main types of bleeding, there is a further category which is traumatic bleeding. There are different types of wounds which can cause traumatic bleeding, and these can be categorised as follows: Abrasion- also known as a graze, where an object brushes on the skin but does not break it. Hematoma- where blood vessels are damaged, causing blood to collect under the skin. Laceration- where a blunt impact to soft tissue causes a deep wound. Incision- where a precise cut is made into the skin. Puncture Wound- where an object penetrates the skin and deeper layers. Contusion- also known as a bruise, where a blunt trauma causes damage under the skin, but does not break it. Crushing injuries- where a great amount of force is applied over a period of time, causing initially internal bleeding. Ballistic trauma- where a projectile weapon has entered and exited the area of the body, causing a wound between the two. Scenes of Crime officers attend many types of crime scene where blood is present. These include: Burglary- When an offender breaks a glass window or door to gain entry to a premises, they risk cutting their hands/arms. This leads to blood being left on fragments of glass in the window and on the floor. Assault/Wounding- Open wounds are normally the result of an attack on a victim. Blood can be left at an assault scene on the weapon that was used in the assault, on the ground, on the offender and on the victim. If the victim is bleeding heavily then blood will be left whenever the victim comes into contact with another surface. Manslaughter/Attempted Murder/Murder- Blood left at these scenes is not only important for swabbing purposes, but the pattern in which the blood is left can determine the order of events at a major scene. Road Traffic Crash- Blood at this scene can be found in the victims car and, if involved, the offenders car. This is important as it can place people in their respective cars- allowing investigators to work out the positions of people at the time of the incident. The collection, packaging and preservation of blood evidence at a crime scene should not take place until the scenes of crime officer has documented the bloodstain patterns (Lee, Palmbach and Miller 2001). Whenever biological fluids are encountered at a crime scene, protective clothing, gloves and masks should be worn due to the biohazard nature of blood (Lee, Palmbach and Miller 2001). To recover dry blood, an area near the blood that is unstained should be swabbed using a sterile swab, as a control sample (Derbyshire Constabulary 2008). Then, the stain should be swabbed using a sterile swab that has been moistened using sterile water (Derbyshire Constabulary 2008). The remains of the stain should then be dry swabbed using a sterile swab (Derbyshire Constabulary 2008). The swabs should be returned to their tubes immediately and stored frozen as soon as possible (Derbyshire Constabulary 2008). A batch control of both the water and swabs should always be made, and should be exhibited separately to the swabbed stain and background control (Derbyshire Constabulary 2008). Items that have areas of dried blood on them should be packaged in paper bags which are sealed securely and clearly marked as biohazard. Blood and bloodstained evidence should never be packaged in airtight containers (Lee, Palmbach and Miller 2001). To recover wet blood, a control swab of the surrounding area of the stain should be taken using a sterile swab (Derbyshire Constabulary 2008). The wet stain should then be swabbed using a dry, sterile swab (Derbyshire Constabulary 2008). The swabs should be returned to their tubes immediately, and should be stored frozen as soon as possible (Derbyshire Constabulary 2008). Again, a batch control of the swab should be exhibited separately (Derbyshire Constabulary 2008). If a removable item has an area of wet blood on it, then the entire object should be exhibited and left to dry in a drying room at the police station. Often at crime scenes, stains that are composed of unknown substances can easily be confused with blood. Identifying whether a substance is blood allows further analysis to confirm species, and the individual (Spalding 2006). II.IV Presumptive Tests for Blood James and Nordby (2005) say that a presumptive test is one which allows the scenes of crime officer to make a qualified conclusion that blood is present in the tested sample, when positive. They also say that when a test is negative, stains that need no further consideration are eliminated. Presumptive tests may be recognised as those that produce a visible colour reaction or those that result in the release of light (James and Nordby 2005). Both of these rely on the catalytic properties of blood to drive the reaction (James and Nordby 2005). Lee, Palmbach and Miller (2001) write this as a chemical reaction: AH2 + H2O2 Æ’Â   A + 2H2O Oxidisable chemical Hydrogen peroxide Haeme Oxidised (colourless) (peroxidise) James and Nordby (2005) state that catalytic tests involve the chemical oxidation of a chromogenic substance by an oxidising agent catalyzed by the presence of blood. They also say that the catalyst of the reaction is the peroxidise-like activity of the haeme group of haemoglobin. Cox (2004) describes the attributes that a good presumptive test for blood should be sensitive, specific, quick, simple and safe. In order for presumptive tests for blood to function properly, they must detect a component of blood (Tobe, Watson and Daà ©id 2007). Most presumptive tests therefore act on the peroxidise activity of haemoglobin. This component is not found in the everyday environment, but other substances found in items such as fruit and vegetables perform a similar function (Tobe, Watson and Daà ©id 2007). A very popular presumptive method is the phenolphthalein test, which is also known as the Kastle- Meyer test (Virkler and Lednev 2009). Lee, Palmbach and Miller (2001) say that the Kastle-Meyer test was introduced in 1901 by Kastle. Phenolphthalein will cause an alkaline solution to turn pink after it has been oxidised by peroxide when blood is present (Spalding 2006). The reagent consists of reduced phenolphthalein in alkaline solution, which is oxidised by peroxide in the presence of haemoglobin (James and Nordby 2005). The test result is normally immediate, and a positive result a minute or more after the test is performed is usually not considered as reliable (James and Nordby 2005). It has a sensitivity of 1:100,000 (Lee, Palmbach and Miller 2001). James and Nordby (2005) say that Adler and Adler in 1904 investigated the reduced or colourless form (leuco) of the dye malachite green, which is also referred to as McPhails reagent. This test involves the Leuco base of malachite green (Lillie 1969). Leucomalachite Green oxidation is catalyzed by haeme to produce a green colour (James and Nordby 2005). The reaction is usually carried out in an acid medium with hydrogen peroxide as the oxidiser (James and Nordby 2005). It has a sensitivity of 1: 20,000 (Lee, Palmbach and Miller 2001). Bluestar is a luminol preparation developed by Professor Loic Blum in France that is extremely sensitive and stable and produces a very bright, long lasting chemiluminescence (James and Nordby 2005). The extreme sensitivity of Bluestar Forensic allows detections of bloodstains down to 1:10,000 dilutions (Bluestar Forensic 2004). It does not require total darkness to be visible, and works well on either fresh blood or old bloodstains (Bluestar Forensic 2004). Bluestar works by mixing the Bluestar Forensic solution with Bluestar Forensic tablets, which is then left to dissolve. This is sprayed onto the area of suspected blood. A positive result will cause a bluish luminescence (Bluestar Forensic 2004). The Hemastix test, created by Miles Laboratories in 1992, is particularly useful when solutions can be hazardous, or inconvenient (James and Nordby 2005). The test consists of a plastic strip with a reagent treated filter tab at one end (James and Nordby 2005). The tab contains TMB, diisopropylbenzene, dihydroperoxide, buffering materials and non reactants (James and Nordby 2005). A bloodstain is tested by moistening a swab with distilled water, sampling the stain, and touching the swab onto the reagent tab on the strip (James and Nordby 2005). The tab is normally yellow, and turns form orange to green or blue when positive. Quality control testing is necessary and should be completed with known blood samples on every new batch of test reagents to verify that the reagents are working as expected (Lee, Palmbach and Miller 2001). II.V False Positives Sutton (1999) points out that a false positive is an apparent positive test result obtained with a substance other than blood. James and Nordby (2005) say that misleading results can be attributed to Chemical oxidants (often producing a reaction before the application of peroxide) Plant materials (vegetable peroxidises are thermolabile) Materials of animal origin (that contain traces of blood). Substances that produce false positives generally take detectably longer to react and, therefore, may be eliminated through observational interpretation (Tobe, Watson and Daà ©id 2007). False positives were initially noted only with copper salts (Glaister 1926). Tobe, Watson and Daà ©id (2007) state that saliva, semen, potato, tomato, tomato sauce, tomato sauce with meat, red onion, red kidney bean, horseradish, 0.1 ascorbic acid, 5% bleach, 10% cupric sulphate, 10% ferric sulphate and 10% nickel chloride are all known false positives. Bluestar False Positives (2008) say that Bluestar has false positives that include oil based paint, alkyd varnish, turnip, banana, leek, green bean, carrot, ginger, manganese sulphate, copper sulphate, iron sulphate and potassium permanganate. Lee, Palmbach and Miller (2001) write that many household cleaning products contain oxidising agents that can produce false positives. Many fruit and vegetables produce false positives including apples, horseradish and broccoli (Lee, Palmbach and Miller 2001). Bleach is a false positive that provides an (immediate and intense reaction) according to Gardner (2005). Hunt et al (1960) say that faeces often gave a false positive depending on the food that had been eaten previously. Ponce and Pascual (1999) state that lemon juice added to a bloodstain can cause a positive result due to its acidity. A false negative is when there is some interference with the oxidation-reduction reaction, normally in the presence of a strong reducing agent, which results in a delay of the oxidation reaction; thus resulting in a coloured formation (Lee, Palmbach and Miller 2001). False negatives are less common but problematic as an actual blood sample may be overlooked or left at the scene (Lee, Palmbach and Miller 2001). Many of the false positive reactions can be identified during the presumptive testing procedure if any changes observed and the exact point in the reaction of these changes is recorded and compared to that of blood (Lee, Palmbach and Miller 2001). Chapter III. Experimental Methodology I will be investigating known substances previously reported by other authors that show a false positive and then analysing other substances similar to those already known to see if these also produce a false positive. III.I Project Design Each of the substances will need to be repeated to ensure a wide enough range of consistent results. Therefore, a grid will be drawn on a piece of Perspex measuring 1.5m2, and a piece of filter paper placed in each of the grid spaces, to allow the even distribution of substances and to allow the easy identification of false positives. Blood Known False Positives Unknowns 1 2 3 1 2 A New technique to detect metabolites from a single drop of blood B New technique to detect metabolites from a single drop of blood C New technique to detect metabolites from a single drop of blood Figure 4- A diagram to illustrate an example of the project layout. For each of the presumptive reagents tested, the filter paper in each grid space will be exposed to a substance to be tested. This will be allowed to dry for a minimum of 1 hour. Each substance will then be tested with a reagent. Each substance will be repeated three times to give a fair indication of performance. The time taken for a substance to register a positive result will be recorded. If a colour change occurs then the test will be classed as positive. If no colour change is noted within 5 minutes of the reagent being added, then the test will be classed as negative. III.II Sample Preparation The substances that I have chosen to analyse are known false positives as reported by other authors and then substances allied to known false positives. Known false positives to be tested: Horseradish. Tomato Sauce. Red Onion. Turnip. Lemon Juice. Bleach Solution (5%). Unknown substances to be tested: Brown Sauce. BBQ Sauce. Radish. Dark Chocolate. Orange Juice. Bleach Solution (less than 5%). III.III Choice of Presumptive Tests I have chosen to use the following presumptive reagents to test substances for false positives: Kastle-Meyer. Hemastix. McPhails. Bluestar. III.IV Control Tests I will test all of the presumptive tests on blank filter paper before proceeding to test with substances. This ensures that there is no reaction from the filter paper to the presumptive tests. I shall also test all of the presumptive tests with horse blood before proceeding to test with substances. This shows that the tests do recognise a sample of blood. I have chosen to use 2.5g of each substance as I feel this is an amount that is representative of a stain at a scene. Blood is reported to have been diluted to 1:10000 in previous tests, and as this dilution has proved the most successful, I have chosen to use this dilution. REARRANGE + FINISH

Critical Issues of Soil Erosion Problems

Soil quality is one of the most basic and perhaps least understood indicators of land health. Soil supports plant growth and represents the living reservoir that buffers the flows of water, nutrients, and energy through an ecosystem. The ongoing degradation of the earth†s soils by human activity, particularly agriculture, threatens human potential to feed a growing population. The annual global erosion amounts to about 36 billion tons, of which 10 billion are due to natural causes and 26 billion are the result of human activity (Crosson et al. 995). The soil or runoff that has been eroded ends up in groundwater, lakes, streams, and rivers. The deposits of excess soil and the contaminates in it, cause further ecological complications. Bodies of water need to be dredged and monitored for contamination. Water levels are lowered with the increasing soil eroded into them, making our world†s water supply a concern directly related to the erosion of soil. The process of soil renewing itself is largely unknown. However, there is consensus on the need for conservation. Evaluating the scope of the problem or predicting the effects that various solutions might have on agriculture and the environment is very difficult. Degradation is gauged for all soil in terms of compaction, erosion, nutrient loss and loss of organic matter. Soil quality refers to the capacity of a soil to perform these beneficial functions. Its texture, structure, water-holding capacity, porosity, organic matter content, and depth, among other properties determine a soil†s quality. Because soils naturally vary in their capacity to perform these functions, we must tie our understanding of soil quality to landscapes and land use. We must understand soil quality for two important reasons: First, we must match our use and management of land to soil capability. Second, we must establish understanding about soil quality so we can recognize ongoing trends. If soil quality is stable or improving, we have a good indicator that the ecosystem is sustainable. If soil quality is deteriorating, the larger ecosystem will almost certainly decline with it (Wilken 1995, Mirzamoatafa et al. 1998). Many conservation efforts are being taken to control soil erosion. In order to do this a universal language is need to measure soil erosion, texture, and the potential for erosion. Soil loss tolerance (â€Å"T†) is the amount of a given soil that can be displaced by water or wind erosion each year and be replenished through natural soil regeneration processes. This is a basis for evaluating the impacts of soil erosion and develops objectives for conservation treatment. Erosion at rates greater than T is a special concern because it threatens agricultural sustainability. Enrichment Ratios (ER) often used as a measure of the nutrients available for soil. It is a ratio of the intrinsic potential for soil displacement from erosion to the â€Å"T† limit (Baffaut et al 1998). From 1991 to 1992 in Central Kenya†s highlands, these formulas were used to monitor runoff, soil loss, and enrichments of eroded soil material. Annual rainfall was 948 and 1125 mm for 1991 and 1992. Soil loss ranged from 0. 8 to 247. 3 tons, and runoff ranged from 1 to 89 mm. The enrichment ratios (ER) were [greater than or equal to] 1 and sediments were mostly enriched with P and Na. The P and Na concentrations were 4 to 10 and 2 to 3 times the source material. Sediment from the plots was 247 to 936% richer in P than the soil from which it originated. Too much P can have negative effects on the plant and wildlife surrounding it. Changes in soil pH, percentage organic C, and percentage total N following erosion were significantly correlated with cumulative soil loss (r values of 0. 77, 0. 59, and 0. 71, n = 20). The data indicated that the unbalancing of nutrients in the soil is due to erosion, and one of the major causes of soil fertility depletion of Kenyan soils (Gachene et. al. 1997). The Universal Soil Loss Equation (USLE) estimates average annual soil loss from sheet and till erosion. The equation is: A=RKLSCP, where A is the computed soil loss per unit area, R is a rainfall factor, K is a soil erodibility factor, L is a slope length factor, S is a slope degree factor, C is a crop practice factor, and P is a conservation practice factor (Baffaut et al 1998). Data from erosion plots in Tarija suggest only moderate rates of erosion (200tons-per. yr. ). Data at 6-min intervals for 41 sites in the tropics of Australia were used to compute the rainfall and runoff factor (R-factor) for the Universal Soil Loss Equation (USLE), and a daily rainfall erosivity model was validated for these tropical sites. Mean annual rainfall varies from about 300 mm at Jervois to about 4000 at Tully. For these tropical sites, both rainfall and rainfall erosivity are highly seasonal. The daily erosivity model performed better for the tropical sites with a marked wet season in summer in comparison to model performance in temperate regions of Australia where peak rainfall and peak rainfall erosivity may occur in different seasons (Yu 1998). The Wind factor must be considered when evaluating soil erosion. Plant nutrients are transported in windblown sediment. The Wind Erosion Equation (WEQ) is designed to predict long-term average annual soil losses from a field having specific characteristics. The equation is E=f (IKCLV), where E is the estimated average annual soil loss, I is the soil erodibility, K is the ridge roughness factor, C is the climatic factor, L is the equivalent unsheltered distance across the field along the prevailing wind erosion direction, and V is the equivalent vegetative cover (Baffaut et al. 1998). As validation for the Wind Erosion equation (WEQ) two field sites were established in southern Alberta (one in 1990, one in 1993). At Site 1, total N in windblown sediment trapped at 25-cm height showed an average (13 events) enrichment ratio of 1. 11, while organic C in windblown sediment showed an average enrichment ratio of only 1. 02 compared with soil from the erodible surface. At Site 2, the average (4 events) total N enrichment ratio was 1. 08 and the average organic C (carbon) enrichment ratio was 1. 05. The results provide further evidence that every effort should be to prevent erosion of the thin layer of surface soil that ensures the future sustainability of agriculture (Baffaut et. al. 1998). These examples of using universal formulas to measure soil erosion allow scientists to evaluate an area and compare efforts that are working else where and apply them to areas were soil erosion is in need of being lessened. During last 40 years, nearly one-third of the world land has been lost by erosion. This loss continues at a rate of more than 10 million hectares per year. The world population†s food demand is increasing at a time when per capita food productivity is beginning to decline (Pimentel et al. 1995). If conditions leading to famine are to be avoided, land that produces food must be preserved. The ecological food web links plants, animals, and people must live in harmony with the planet†s water, soil, and atmosphere. Once those connections are severed the hunger web begins. To avoid these devastating effects, steps must be taking in all aspects of ecology. The greatest impact of soil erosion is farming practices that are ignorant to overall effects on the food web. The key to farming is to grow enough food for all of your people. When towns were made up of small farms this goal was more easily obtainable. When people stop farming, food production then became an industry where money takes precedent over soil. Because of demand and economic reason farmers in the United States are destroying delicate balances in nature and drastically altering the landscape so that soil is at risk of erosion, and is eroded faster than it can be formed. (Pimentel, Resosudarmo1995) Agricultural practices of cropping and tillage are two important factors that influence runoff and soil losses. Much research had been done to show the effects of different tilling and crop rotations on soil erosion. Doyle†s (1996) research concluded that between 1982 and 1992 the US improved or at least had no increase in average erosion rates in most areas with extensive cropland. Some of the improvement found was the result of crops being rotated and better tiling methods. Brown (et al 1998) investigated the effects of combining whey and straw in croplands. This research found that straw or whey alone reduces soil loss by 60-85 percent. When combined they reduce soil loss by 96- 98 percent. Ghidey and Alberts (1998) found through a study in Kansas that the annual runoff and soil losses from soybean cropping were slightly higher than those for corn. These studies and others like them have provided the knowledge of how to prevent further soil erosion. The Conservation Reserve Program pays farmers to remove or add environmentally sensitive crops to their croplands (Ghidey, Alberts 1998). There are many casualties of conventional chemical farming: erosion, a decline in soil quality, water purity, weakened crop resistance to pests and diseases, and the safety of farm workers. According to US News & World Report, 9/14/92, an excess of $4 billion a year is spent on pesticides, fungicides, and herbicides Chemical farmers are still losing about a third of their crops each year to insects, diseases, and weeds. Because of tilling practices, these chemicals used in farming not only effect the food produced and ground water but also the places where the runoff is deposited. Herbicide loss by runoff is a world wide problem. These contaminated runoffs kill a variety of wildlife, aquatic life forms, and many species of vegetation. An economical and environmental alternative to conventional farming is organic crop production. Organic farming is a soil management system that maintains and replenishes soil fertility. Organic foods are produced without the use of synthetic pesticides or fertilizers. The strategy behind organic crop production is to produce food crops which are â€Å"processed, packaged, transported, and stored so as to retain maximum nutritional value without the use of artificial preservatives, coloring, or other additives. Allowable management techniques include: the use of cover crops, manures, and composts for soil fertility management, the use of mulches, hand or mechanical cultivation, and crop rotation for weed management, and production scheduling and crop selection for disease and insect management. Organic farming is not as easy or as productive as conventional farming, especially on infertile sandy soils. To be successful, an organic farmer requires a sound knowledge of soil type, crop management and the incidence of pests and diseases in different seasons (Arden-Clarke et al 1987). Organic production preferably should be combined with systems not usually used in agriculture such as cover crops and livestock farming. This requires a larger area than the normal agricultural holding, which must be chosen carefully. The Department of Agriculture (Elliott et al. 1987) certifies organic production systems. Certification involves the development of an organic plan for the operation, the plan to be evaluated and approved by an accredited agent, and the agreement of the farmer to abide by the list of approved substances. The organic agent also reviews soil and water tests, crop histories, production, and rotation plans. The area in which organic crops are to be grown must be chemical free for 3 years. They verify compliance with standards through annual and spot inspections, and record keeping requirements (Elliott et al. 1987). Consumers are demanding organically grown fruit and vegetables, and are willing to pay a higher price. The sales of organic products have increased from $178 million to over $4 billion in 1998, and is growing in excess of 20% per year. These operations will focus on the production of lettuce, tomatoes, and cucumbers (Us News &World 1998). There is a demand for certified organic vegetables, especially with the new health awareness of the public. As with any type of farming, there is the risk of unfavorable weather and invasive pests, which could, reduced a season†s crop. Economics may be a large controlling factor for soil erosion. . When demand for grain increases, and supply decreases, price for food will increase. Americans can afford to pay a few cents extra for bread, horse food, and rice but poorer countries will suffer when food becomes too expensive. Although the United States has been referred to as the â€Å"bread basket† of the world because of our impressive food production, our history constituted prolific amounts of soil erosion. During the 1930†³s dust clouds forced people from their homes, killed humans and animals alike, and caused snow in Vermont to be black. Agricultural economists are aware that severely eroded soils are less productive–if too much soil is lost, the next planting and harvest are delayed. Soils are less productive if crop planting has to be delayed. Instead of harvesting five times in one season, farmers might only reap three. Severely eroded soils have deficiencies in nutrient, bacteria, alterations in structure, and decreased resistance to pests. Continuously planting row crops, corn for example, can cause severe soil loss. Sustainable agriculture can prevent or lessen soil erosion and ensure higher productivity (Gardner 1996). Our county†s high demand for grain forces farmers to over work their land. The demand for this grain and the human consumption of grown vegetation are not the only factors leading to soil erosion. The beef industry and our consumption of red meat impacts soil erosion as well. Of the total amount of grain that is grown in the US, 80% of it is fed to livestock. To support our meat centered diet, 260 million acres of U. S. forest must be cleared to create cropland for livestock (Gardner1996). Costa Rican produced beef is even more devastating to the environment. For every ? lb. of Costa Rican beef made, one acre of Costa Rican rainforest must be destroyed. This devastation is worsened by the deaths of all the plant and animal species that occur due to habitat loss (Gardner1996). Because of the above reasons and several other moral, nutritional, and economical reasons, beef consumption is bad for the environment. Every individual who switches to a purely vegetarian diet (Gardner1996) spares one acre of trees each year. The factor of agricultural practices on soil erosion becomes more severe when forests, grasslands, and wetlands are destroyed. Roots from trees in forests, grasslands, and wetlands stabilize soil not only by holding earth, but also by intercepting precipitation, dispersing energy of raindrops, and by increasing infiltration and reducing runoff (Smith 1998). Native Americans have used good agriculture practices for years. American Indians had respect for the land and all of its life forms. One of their cultural beliefs about farming is centered on the three sisters: corn, squash, and beans. The corn provides a stalk for beans to climb. Beans produce nitrogen that fertilizes the corn. And squash protects the soil and corn roots from the sun, traps moisture, and prevents erosion. All three plants provide edible food, while preserving soil. (Wilken 1995) It is essential to the survival of the human race, and all other life forms that several forms of soil conservation practices are used. There is a finite amount of food that our country can produce before our production starts to decrease. Although erosion is a natural process, humans have found several unnatural ways to make soil erosion more severe. To be able to continue to feed the growing population and preserve the species diversity of wildlife and plants we need to have sustainable agriculture practices and soil conservation these efforts are crucial in the prevention of extensive soil erosion.

Jim Essay - 2872 Words

†He is sometimes slave who should be master; and sometimes master who should be slave.† [Lat., Fit in dominatu servitus, in servitute dominatus.] Oratio Pro Rege Deiotaro (XI) by Marcus Tullius Cicero Mark Twain’s The Adventures of Huckleberry Finn is considered to be possibly the Great American Novel by many scholars and is certainly the best known of Mark Twain’s works. These scholars both powerfully praise and powerfully depreciate Twain’s artistic judgment in relation to Huck’s character, themes, and political statements, but Jim’s place is often ignored or overlooked. Jim’s character is very important in his roles in supporting Huck as a father figure, his example for Twain’s portrayal of slavery and racism, and in his own right†¦show more content†¦Jim’s concern for Hucks emotional well-being is also shown. He showers Huck with verbal and physical affection. One of the memories that causes Huck to stick with his decision to help free Jim is that of how Jim would quot;always call [him] honey, and pet [him]quot; (161). This was a welcome change to the lonely boy who had only what is in this day and age considered very dreadful child abuse from his real father, boring and self-gratifying lectures from Miss Watson, and tears of pity from the widow. Jim gives Huck more; He gives Huck friendship. Before Jim, Huck never had any true friends. Although Tom comes the closest, he consistently degrades Huck and puts his ideas down. When Huck tries to quot;be his true friendquot; (176) and discourage him from freeing Jim and embarrassing himself and his family, Tom replies by quot;shut[ting] [him] up, and say[ing], `Dont you reckon I know what Im about? Dont I generly know what Im about?quot; (176). Again, when Huck has a sensible idea regarding how to free Jim, Huck puts him down with, quot;Oh, shucks, Huck Finn, if I was as ignorant as you, Id keep stillquot; (182). In spite of their age and social differences, Huck has free, amiable, and easy conversations with Jim. Another one of Hucks memories at a critical dedication point is of when he and Jim were quot;a floating along, talking, and singing, a nd laughingquot; (161). Huck can speak very freely of moreShow MoreRelatedJim Carry1006 Words   |  5 PagesThe youngest of four children born to Percy (an accountant and aspiring jazz saxophonist) and Kathleen, Jim Carrey was an incurable extrovert from day one. As a child he performed constantly, for anyone who would watch, and even mailed his rà ©sumà © to The Carol Burnett Show (1967) at age 10. In junior high he was granted a few precious minutes at the end of each school day to do stand-up routines for his classmates (provided, of course, that he kept a lid on it the rest of the day). Carrey s earlyRead MoreJim Elliot: Missionary627 Words   |  3 Pagesâ€Å"He is no fool who gives what he cannot keep to gain what he cannot lose.† These words were spoken by Jim Elliot early in his life and were words he lived by. Elliot was a dedicated Christian who showed God’s love to everyone by following God’s plan for his life; by his death, he inspired many oth er Christians to go into the mission field. Jim Elliot was a Christian completely dedicated to God and his love of others which he showed by trusting God in every situation of his life. Elliot put his faithRead MoreBiography of Jim Morrison618 Words   |  3 PagesJim Morrison remains one of the most popular and influential singers and writers in rock history; they became famous on the classic rock radio stations. 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At one level, the deaths at Jonestown can be viewed as the product of obedience, ofRead MoreJim Jones Essay1676 Words   |  7 PagesThe mass suicides, that took place under the influence of Reverend Jim Jones, can be explained from a sociological perspective. By looking at how the group dynamics played into the outcome one gets a better idea of the whys? of the massacre. The sociological explanation is but one way to explain this horrific event. It is , however, the only one explored in this essay for reasons of concision. At one level, the deaths at Jonestown can be viewed as the product of obedience, of people complyingRead More Jim Morrison Essay examples1441 Words   |  6 Pages I dont quite recall when I first heard a Doors song, but I could safely assume that it was Jim Morrison wailing the tune quot;Light My Firequot; or quot;Break on Throughquot;. After all, these two anthems are the foundations upon which the Doors legend was built, and to this day remain the bands gems. But as I have come to learn through the years of reading about and scouring over regurgitated bits of information of this group is that they are so much more than a member of the genre of thoseRead MoreEssay on Jim Jones as a Prophet770 Words   |  4 PagesJim Jones as a Prophet November 18, 1978 it all ended. Jim Jones and his followers committed mass suicide in Guyana, South America. The history of Jim Jones and the Peoples Temple is still studied a great deal today. Why did all those people follow Jones? Were they forced, were they brain washed, or was Jones just that charismatic. In this paper we will probe deep into Jonestown and answer some of these questions. We will be using Max Webbers article TheRead More The Jonestown Massacre: Jim Jones881 Words   |  4 Pagescult society led by Reverend Jim Jones, named Jonestown. Jonestown was a small community in the jungle of Guyana, South America. After getting word of people coming to investigate the society, Jones had committed a mass suicide by poisoning Kool-Aid and giving it to the people of Jonestown. A cult society is an organization that basically disguises itself as a religion. In a cult, they normally perform rituals. There are usually many people in these societies. In Jim Jones’s cult, there were atRead MoreThe life of Coach Jim Harbaugh1546 Words   |  6 PagesLove for The Game Born in Toledo, Ohio, one of the most energetic and smartest coaches to ever step onto a sideline, this man is Jim Harbaugh. Son of Jack Harbaugh who spent a majority of Johns childhood coaching at the University of Michigan before moving out to California for a different job. Growing up around the team Jim had the opportunity to get close with the coach, a man named Bo Schembechler. Already having a relationship it really was no surprise when Bo started recruiting one ofRead MoreCodex Alera By Jim Butcher1074 Words   |  5 Pagesâ€Å"Codex Alera† is a fantasy series written by Jim Butcher, and there are only six books to the series. Unlike Butcher s â€Å"Dresden Files†, â€Å"Alera† is swords and horse fantasy that is set in the realm of Alera, a place that is a lot like Rome. It focuses on Tavi, a boy in the first book, as he grows up and becomes a man. The series features magic in the form of furies. Everyone in this universe can wield them. Furies are spirits that are elemental, and include water, metal, wood, fire, air, and earth

Summary Of The Invisible Man - 1612 Words

Keenan Fix Essay 1: The Invisible Man History 228 Professor Harris 5-7 Pages Finding awareness through a journey Throughout the novel The Invisible Man, the narrator struggles with constant prejudice and racism. These negative experiences in many ways shape his opinions and the way in which he views the world. The narrator suffers indignities at the hands of white men early on and no matter what he does he seems to be attacked in part because of his race. The narrator believes he is metaphorically invisible because society doesn’t see him as an individual but as a collection of negative racial stereotypes. In his view no matter what he does or achieves he will be seen as an African American man not just as a man. The narrator is the victim of the racism which was exceedingly common place at the time and as a result of this and constantly being labeled decides to go underground. He is a victim of his circumstances and as a result is deceived and exploited by both whites and African Americans many of whom he is supposed to trust. The narrator goes along with ideas thus in some ways not coming to the conclusion of what is truly right on his own. Others who supposedly have his best interest manipulate him after they gain his trust and then in turn betray him. Early on the narrator who is obviously quite bright allows others to use him for their own benefit. He is initially exceedingly trusting of others and doesn’t contemplate what their exteriorShow MoreRelatedSummary Of Invisible Man1450 Words   |  6 PagesIn 1936, Ellison went to New York City for an internship and while he was there he earned money for his college expenses. He was a researcher and writer in New York for The Federal Writers Program. Plot Summary: Invisible Man is a story by Ralph Ellison, told in the point of view of a black man from the South whose name is never revealed, who we just refer to as the narrator. He is haunted by the warning his grandfather gave to not conform to the wishes of white people. The first time the narratorRead MoreSummary Of The Invisible Man 2605 Words   |  11 PagesThe invisible man begins his journey as a young, naà ¯ve student who is bewildered as he experiences his first taste of blindness. The narrator is a gifted, student with a specialty orating speeches; he and a few other boys are invited to a ceremony but are actually used for â€Å"white entertainment†. They are forced to look upon an unattainable American dream, represented by a nude woman, â€Å"†¦and in the center, facing us, stood a magnificent blonde—stark naked[†¦]Had the price of looking been blindnessRead More Betrayal of Self in Ellisons Invisible Man Essay1310 Words   |  6 PagesBetrayal of Self in Ellisons Invisible Man   Ã‚  Ã‚  Ã‚  In Ralph Ellisons Invisible Man, the nameless narrator is betrayed by a handful of different characters--for this reason his life remains in a constant state of upheaval throughout the novel. Confusion and a lack of personal vision cause the Invisible Man to trust many characters whose designs for him are less than virtuous. Oftentimes these characters betray the Invisible Man, whose reactions to said betrayals form the greater part ofRead MoreInvisible Man By Ralph Ellison1366 Words   |  6 Pagesroyal originated with the Romans, more than two millennia ago, when gladiators would duke it out with no protection, ending in a solitary blood stained fighter left standing, amidst unbridled carnage. The titular narrator of Ralph Ellison s novel Invisible Man, is no stranger to those experiences. In the beginning, he is forced to fight several other black boxers for the amusement of many heckling, white spectators. Through the imaginative use of objects, symbols, a llusions, and the actions, thoughtsRead MoreInvisible Man Character Analysis1533 Words   |  7 PagesIf you skipped from the end of the prologue of Invisible Man, by Ralph Ellison, all the way until the protagonist’s eviction speech, you would probably pick up the plot and character developments without a problem. The first few ordeals described in the novel can be infuriating because of the narrator’s naà ¯ve outlook and his persistence in trying to follow a ‘respectable’ path upwards in life. All of the psychological shifts that lead up to the captivating scenario from the first few pages happenRead MoreInvisible Cities By Italo Calvino1395 Words   |  6 PagesItalo Calvino’s (1923-1985) novel Invisible Cities consists of a number of dialogues between traveller Marco Polo and the Tartar Emperor Kublai Khan. Traveller Marco Polo tells Kublai Khan tales of the numerous cities of his empire, which the Khan himself will never visit. The men pla y with the notion that an understanding of the world’s cities will inform the emperor on how to govern his realm (Bloom 2001). Each city cannot be compared, as they are all radically different from one another. CalvinoRead MoreMetaphor, Metonymy and Vioce895 Words   |  4 Pageswas defined as the substitution based on the resemblance or analogy and then she goes on to the metonymic meaning which she defines as the basis of a relation or association other than that similarity. Paul De Man, a deconstructionist literary critic and theorist, provides a brief summary stating the preference for the metaphor over metonymy by aligning analogy with necessity and contiguity with chance. According to him, â€Å"’the element of truth’ is the product of a purely rhetorical and ultimatelyRead MoreWomen’s Income Inequality and The American Dream Essay1358 Words   |  6 Pagesthere has always been some sort of inequality. Right from the start we had slavery, degra ding African Americans and not giving them equal rights, as a white man would have. That lasted for a long time and then the great depression was next, creating income inequality, killing the economy and ruining the job field for the average working man, and now a days it isn’t any better. We are still currently going through hard economic times that have a big impact on jobs, like Robert Frank says, â€Å"†¦ duringRead MoreCritical Analysis of The Lottery695 Words   |  3 Pagesother towns were getting rid of the lottery. There is one man, Old Man Warner, the town elder is disgusted of the thought of ending the lottery. He has been around for the lottery since he was a child. The black box that the paper is drawn from is a very significant item to the lottery. The current black box is thought to be made from parts of the original black box. â€Å"One by one each male head of the household (or woman if there was no man to take her place) walked up to the box in alph abetical orderRead MoreFree Market Economy: Capitalism and Freedom by Milton Friedman948 Words   |  4 Pagesâ€Æ' What is a free market really? By definition a â€Å"Free market† is a summary term for an array of exchanges that take place in society† (Econlib). However there is more to it than that, in fact there is much to be learned and understood from a free market. A free market is a place (physical or not) where a person(s) in a community are able to go and exchange goods based on supply and demand. A truly free market has no barriers to entrance or to exit, and many goods and services. In any case people