Why does the organic carbon content of sediment reduces with increasing disatnce from a sewage discharge?
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Because sewage is made up of a lot of hydrocarbons.  with increasing distance from a sewage discharge, the sewage is more likely to be diluted by the ocean water.  Therefore, the "relative" organic carbon content decreases away from the discharge area.
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Mostly water (!), dissolved atmospheric gases, including CO2 which makes it slightly acidic, NOx and SOx compounds which also make it acidic and particulates. The significance of the dissolved and particulate compounds cannot be underestimated in this day and age, for example it is now true that the majority of pollutants enter Lake Superior (which, granted, has a small, forested watershed) through atmospheric deposition rather than inflow off the watershed.
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Decomposed rock and organic matter.
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Bacteria is added to it to speed up the degrading.
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Erosion is the displacement of solids (soil, mud, rock and other particles) by the agents of wind, water or ice, by downward or down-slope movement in response to gravity or by living organisms (in the case of bioerosion).\n\nDeposition, also known as sedimentation, is the geological process whereby material is added to a landform. This is the process by which wind, water or ice create a sediment deposit, through the laying down of granular material that has been eroded and transported from another geographical location.\n\nDeposition occurs when the forces responsible for sediment transportation are no longer sufficient to overcome the forces of particle weight and friction, which resist motion. Deposition can also refer to the build up of a sediment from organically derived matter or chemical processes. For example, chalk is made up partly of the microscopic calcium carbonate skeletons of marine plankton, the deposition of which has induced chemical processes (diagenesis) to deposit further calcium carbonate.
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wow.. tdhat is a BIG subject and I have studied soil conservation for many years and to put that answer down into a few words is DIFFICULT... just as difficult as conserving soil.\n\nCaring for our soil resources is becoming increasingly critical as the supply of dependable agricultural land decreases from competition by other uses, such as urban development. Healthy soils are key to producing good harvests of crops, and minimizes expenses such as fertilizer and pest control. If we let agricultural soils become degraded, there will be no new soil to take its place\n\nHere are just a few things to be considered:\n\nMinimize or eliminate summer fallow \nSeed directly into the previous year's stubble without pre-seeding tillage. No-till increases soil organic matter, enhances water infiltration, conserves moisture and reduces runoff and soil erosion due to wind, water and tillage. \nReduce tillage: replace one or more tillage operations with herbicide application to control weeds. Reduced tillage over successive years improves the physical and chemical properties of the soil, and at the same time helps restore organic matter – plant roots, microorganisms, insects and earthworms – which, when left undisturbed, work to stimulate and sustain plant growth. \nExtend crop rotations, particularly with the inclusion of legumes. The benefits include improved fertility, tilth, aggregate stability, moisture storage, and resistance to soil erosion and degradation, as well as reductions in insect, weed and disease problems. All of these factors contribute to increased productivity. \nAdopt permanent conservation practices such as grassed waterways, perennial grass barriers, and strip cropping. \nManage manure not as a waste, but as an important source of organic matter and plant nutrients. Organic matter, and the organisms that eat it, can improve water holding capacity, nutrient availability, and can help protect against erosion. However, applying manure in the fall or over-application can lead to water and air pollution. \nManage irrigation effectively, by reducing water losses from spray drift and over-application. \nCarefully manage fertilizer by applying according to the crops needs, during the time that the crop needs it and close to the root system so it can be utilized efficiently. Although fertilizer can increase the amount of organic matter in the soil, mis-management can also pollute air and water. \nManage pesticides carefully, by following label instructions. Try to minimize pesticide use by using an integrated approach, which incorporates other pest control practices such as a varied crop rotation and biological control options. \nMaintain healthy grass cover on pastures to prevent soil erosion, by using practices such as rotational grazing and rest periods. \nKeep crop residues on soil surface as much as possible. Crop residues include roots, chaff, stems and leaves which are left after a crop is harvested. These residues improve several soil properties, such as organic matter replenishment, water infiltration, water storage and particle aggregation. Crop residues also contain nutrients, including nitrogen, phosphorus, potassium, sulphur and micronutrients. \nSeed forages to increase soil organic matter, reduce erosion and salinity, and recover nutrients that leached below the rooting depth of annual crops. Selection of forage species and management practices can be tailored to specific problems such as drought, excessive soil moisture, salinity, poor soil structure, low pH and other problems. \nProvide adequate wind barriers, such as shelterbelts, to reduce wind erosion. Shelterbelts have the added benefit of increasing crop yields by trapping more snow, particularly of less drought-tolerant crops such as canola and alfalfa. \nPlant cover crops late in summer to protect soil against late fall and early spring erosion. Cover crops store nutrients for the crops that follow them, keep weeds down, host beneficial insects a
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This depends upon how dirty the water is.  If the dirty water is clogged with material bits then that will slow it down.  If the dirty water is dirty in color only it should be equal.
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To keep our used water from spoiling our water resources, we have to remove the pollutants before the water gets back into the environment. In urban areas in most developed countries, the wastewater from homes, businesses and factories is collected by a system of underground pipes-- sewers-- which carry it to one or more central treatment facilites. Most of these are located near bodies of water into which the treated wastewater is discharged. \n\nIn the U.S., all such facilites must have a permit issued by the federal and/or state government, describing limits on the amounts of various pollutants which may be discharged. The U.S. EPA (Environmental Protection Agency) refers to these as NPDES (National Pollutant Discharge Elimination System) permits. Industries located in areas where they are not connected to a sewer can discharge directly into a waterway, but will need a permit, and will probably have to have their own treatment plants. Even industries which are connected to sewers may have to pretreat their wastewaters before discharging them into the sewers, because they may contain materials which will harm the sewers or the treatment plants-- or may be a danger to the people who work in maintaining the sewer system.\n[If you are some one who works in an industrial pretreatment program, you may be aware that the USEPA has recently (July 22, 1999) proposed a series of changes to the current regulations. I have prepared a summary of the proposals which you may find helpful before reading the entire document.] \n\nHomes in non-urban areas that are not connected to a sewer are usually required by their town to have on-site treatment systems. Most common for single homes are septic systems, which consist of a buried tank connected to a set of perforated pipes, embedded in gravel, which distribute the water into the soil. (The "Links" page has several references on this subject.) Larger housing complexes may have treatment systems based on the principles used in full-scale sewage treatment plants. \n\n\nA Word About Sewers: Besides having a set of sewer pipes-- called, strangely enough, sanitary sewers-- which carry wastewater to a treatment plant, cities and towns also need pipes to collect stormwater. These are needed to prevent street flooding and usually lead directly to a waterway without any treatment. The runoff of pollutants from streets and yards into these storm sewers contain oil and other automotive wastes, which may contain toxic metals and organic compounds-- as well as pesticides and nutrient-containing fertilizers from lawns and gardens, and pathogenic microorganisms from animal wastes. The problem of pollution from storm sewers is currently being addressed by the USEPA. Further complicating the situation is the fact that while some cities and towns have completely separate sanitary and storm sewer systems, many others have combined systems. During rainy periods, combined sewers cause two problems: overloading of the treatment plant with extra water and contaminating waterways with untreated sewage from overflows. Even in cities with separate sewer systems, the flows to the treatment plants often increase greatly when it rains because of cracks or separations in the pipes, which allow groundwater or stormwater from broken storm sewer pipes to infiltrate into the sanitary sewer-- or from direct inflow of stormwater into manholes and from illegal connections of roof drains and sump pumps in buildings.*
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Biodegradation\nBiodegradation is nature's way of recycling wastes, or breaking down organic matter into nutrients that can be used by other organisms. "Degradation" means decay, and the "bio-" prefix means that the decay is carried out by a huge assortment of bacteria, fungi, insects, worms, and other organisms that eat dead material and recycle it into new forms. \n\nIn nature, there is no waste because everything gets recycled. The waste products from one organism become the food for others, providing nutrients and energy while breaking down the waste organic matter. Some organic materials will break down much faster than others, but all will eventually decay.\nBy harnessing these natural forces of biodegradation, people can reduce wastes and clean up some types of environmental contaminants. Through composting, we accelerate natural biodegradation and convert organic wastes to a valuable resource. Wastewater treatment also accelerates natural forces of biodegradation. In this case the purpose is to break down organic matter so that it will not cause pollution problems when the water is released into the environment. Through bioremediation, microorganisms are used to clean up oil spills and other types of organic pollution. Composting and bioremediation provide many possibililites for student research. \n\n\n\nhttp://ei.cornell.edu/biodeg/\nhttp://en.wikipedia.org/wiki/Biodegradation\nhttp://www.glossary.oilfield.slb.com/Display.cfm?Term=biodegradation
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I am working on this problem without knowing if you even still need this info. But it is interesting. It seems the most important inorganic nutrient is sunlight!\n\nHere's a quote:\n\nAutotrophs absorb sunlight energy and transfer inorganic mineral nutrients into organic molecules. The autotrophs of the marine environment include algae and flowering plants and in the deep sea are chemosynthetic bacteria that harness inorganic chemical energy to build organic matter...AUTOTROPHIC NUTRITION..supply food molecules to organisms that can't absorb sunlight.\n\nfrom:http://darter.ocps.net/classroom/klenk/Ecology.htm\n\nHere's another link relative to the subject, I think:\nhttp://pubmedcentral.com/articlerender.fcgi?artid=18283\n\nThe oceanic distribution of cadmium follows closely that of major algal nutrients such as phosphate. The reasons for this “nutrient-like” distribution are unclear, however, because cadmium is not generally believed to have a biological function. Herein, we provide evidence of a biological role for Cd in the marine diatom Thalassiosira weissflogii under conditions of low zinc, typical of the marine environment. Addition of Cd to Zn-limited cultures enhances the growth rate of T. weissflogii, particularly at low pCO2. This increase in growth rate is reflected in increased levels of cellular carbonic anhydrase (CA) activity, although the levels of TWCA1, the major intracellular Zn-requiring isoform of CA in T. weissflogii, remain low. 109Cd label comigrates with a protein band that shows CA activity and is distinct from TWCA1 on native PAGE of radiolabeled T. weissflogii cell lysates. The levels of the Cd protein are modulated by CO2 in a manner that is consistent with a role for this enzyme in carbon acquisition. Purification of the CA-active fraction leads to the isolation of a Cd-containing protein of 43 kDa. It is now clear that T. weissflogii expresses a Cd-specific CA, which, particularly under conditions of Zn limitation, can replace the Zn enzyme TWCA1 in its carbon-concentrating mechanism.\n\nMarine microorganisms are largely responsible for the cycling, and therefore the distribution, of many nutrients in the sea, and it is the availability of these nutrients that, in turn, controls oceanic primary production. This relationship is as true of essential trace elements as it is of major nutrients. In oceanic systems, the water column distribution of many biologically important trace metals is thus similar to that of the major nutrients: phosphate, nitrate, and silicate. At the surface, where photosynthetic activity depletes algal nutrients, such metals are present at extremely low concentrations, presumably as the result of biological uptake. Like those of major nutrients, these metal concentrations increase at depth because of decomposition of organic matter and remineralization.\n\nZinc, which has many known biological functions (1), is a good example of a metal that follows this type of nutrient-like profile. Cadmium, however, which is generally thought to be universally deleterious to living organisms, also has a nutrient-like profile (2); its concentration is so well correlated to that of phosphate that the accumulation of Cd in the fossilized tests of marine invertebrates is used as a measure of past nutrient concentrations in the sea (3). In the absence of a demonstrated biological function for Cd, it has been widely thought that abiotic processes, such as adsorption onto organic particles, modulate the distribution of this metal. Recently, it has been proposed that the depletion of Cd from surface seawater is caused by its use by marine phytoplankton (4). Under conditions of Zn limitation, Cd enhances the growth rate of some marine phytoplankton in culture (4–6), and it thus seems that Cd may replace Zn in some essential biochemical function.\n\nIn Thalassiosira weissflogii, the enzyme carbonic anhydrase (CA) constitutes a major use of cellular Zn (7), and the expression of TWC
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From exactly what you said in bold letters....they break down organic matter.  Otherwise the Earth would be littered with dead animals, leaves, trees, birds etc.  Fungus, bacteria, and insects are all decomposers and a very important part of the Life Cycle.\n\nThe organic matter is then released into the soil and taken up in the raw nutrient/mineral content by plants>animals eat plants>animal dies>cycle repeats.
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Personally when we visit a coral reef we must be careful not to damage it by stepping on it or chipping off pieces for our own use.\nToxic waste and other sewage dumped into the water damages coral reefs, as well as a rise in water temperature that could be caused by global warming.
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Try using a pro-biotic product. The bacteria in the product digests waste. They use this in commercial ponds for cleaning before restocking, and also in oil spills, because it can digest petrol. Ask your local house and garden supplies shop, or if you live near farms ask them.
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That depends on the source you get it from!\n\nIn theory, water has a pH of 7.  If you could separate it from all influences, the disassociation constant of water would keep about 10^-7 M amounts of both [H+] and [OH-].  If you distill pure water and measure the pH, that's what you'll get.\n\nOver a couple hours the pH will change as the pure water absorbs carbon dioxide from the atmosphere.  This reacts with the water to form carbonic acid, lowering the pH to about 5.8.\n\nIn rain and the like, this effect has been countered, however, with other impurities that react with the carbonic acid, as well as producing their own effects.  Sea water has a pH of about 8.0, while water from streams and rain is usually closer to 7.
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It appears as though man has decreased the productivity of the oceans, by runoff of fertilizers and pollutants. Many places like Newfoundland's Grand Banks and the Chesapeake Bay have suffered disasterous declines in productivity. \n\nMan might have also changed the carbon dioxide and dust content of the atmosphere, which might contribute to climate change. Man definitely introduced CFCs into the atmosphere, which has enhanced the size and severity of the springtime ozone holes at the poles.
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You can have too much in your soil..\nNitrifying bacteria such as Nitrosomonas play an important role in providing nitrogen to plants and limiting carbon dioxide fixation. They are found widely distributed in soil or water, where there are large amounts of ammonia, such as lakes or streams into which treated and untreated sewage is pumped. Nitrosomonas does whatever it can to avoid light, and so may appear as clumps of slime in order to protect itself. It is often found on the walls of stone buildings or on the surface of monuments, where its production of nitric acid from the air may cause erosion of the stone beneath. While in some respects Nitrosomonas' effect on ammonia is positive, agriculturally it can pose a problem. Nitrification, the cycle in which Nitrosomonas acts as the initiator by oxidizing ammonia to nitrite, can leave the nitrate in the soil more susceptible to leaching and therefore less available to plants. There are some nitrification inhibitors which slow the nitrification process, making it less possible for the nitrate to be lost due to leaching.
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Forest cover tends to create areas of groundwater recharge and generally slows runoff. Trees tend to buffer the speed which rainfall hits the ground and because they often create areas covered with organic material like leaf litter, the ground has more time to absorb rainfall before it runs off. Bare ground will be subject to erosion as well as higher rates of runoff. \n\nThe burning of trees may contribute to CO2, but is probably insignificant because it is a one time event. The removal of the trees is likely to be accompanied by a long term loss of soil organics, which will also contribute CO2 over time. The real change may be through albedo effects and changes in rainfall related to loss of trees may be an even bigger factor. In Brazil,when trees were removed to be replaced with even darker colored soil, the average temperature of the area increased by about 3 degrees C. Most cities have a heat island around them, often 10% warmer, due to changes in albedo. The lack of trees may change the rainfall patterns, and some hypotheses actually predict that even rain drop size may change. A study in Amazonia known as the Large Scale Biosphere-Atmosphere Experiment is investigating these ideas.