Some of the pollutants associated with the Marine Environment are as follows:
The first in Table 1 is pathogenic materials. These are the living organisms that can produce sickness or biological imbalance in either plants or animals within the ocean itself or in human who either contact oceanic waters or eat the organisms caught in the water.
These include a wide variety or bacteria, protozoa, viruses and fungi. The most common of these are normally associated with human waste products and are found in sewage.
However, other pathogens may occur in non-waste disposal areas where environmental conditions are such that the proper conditions are present for growth and reproduction.
TABLE 1 Pollutants Associated with the Marine Environment:
Oxygen demand materials
Acids and bases
Aesthetically displeasing materials
Sediments are always present to some extent in the marine environment. Generally speaking, concentration of suspended solids increases with proximity to the coast, with the maximum occurring in the reverie and estuarine environment.
As man impinges on the coastal regions, his construction and agriculture efforts generally tend to increase erosion and therefore increase the amount of sediment in suspension.
These sediments have a marked effect on plant growth since they block out a large portion of the light normally reaching greater depths and therefore decrease photosynthetic activity. In some cases rooted plants are completely destroyed by this process.
As sediments are deposited on the bottom they will cover up bottom dwelling organisms (benthos) such as oysters and may even smoothen them under extreme conditions.
In addition to destroying bottom dwelling life, deposited sediments tend to make the water shallower so that, in regions travelled by ships, periodic dredging is required. Dredging and the disposal of dredged material have their own of environmental problems which will be discussed later.
The sediments of concern are primarily inorganic silts and clays since the larger particles such as sand and gravel do not remain in suspension for any non-eligible period of time.
They result from soil being washed from land areas into sea, in many cases because man has changed the character of the affected area by agricultural or construction activities. Once the sediments settles to the natural causes, such as storm, or by man as an operator of a power boat.
The relative importance of recreational vessels in maintaining turbid conditions in shallow water is not well known at this time.
3. Solid Waste:
The disposal of solid waste is a critical urban problem at the present time primarily because areas suitable for the dumping of the sevoluminous materials are becoming scarcer, especially when transportation costs are considered.
Due primarily to low transportation costs the ocean has been used as a dumping ground for solid waste for centuries.
The solid waste most frequently marine dumped is sludge materials left over as a by-product from domestic sewage treatment. However, the unused products of industry and the used-up products of society are also discharged into the sea.
If the product discharged at sea contains materials which may be leached into the oceanic environment, a serious problem could develop, especially if the materials are toxic. However, if the solid materials are inert, a little forethought may result in some benefit to the marine environment. Artificial fishing reefs, for example, have been very successful in certain area, especially for small fish.
On the other hand, solid waste materials also can serve as a pollutant in the sense of destroying habits when this material is dumped into marsh or wetland area. Until recent years marshes and wetlands were assumed to have no practical value, but recently we have found these areas to serve as breeding grounds for most of the commercial species of fish along with many other organisms important in the food chains of all marine creatures. Thus, there is a growing movement not only to save the wetlands from further destruction but also in many cases to attempt to rehabilitate these areas of extreme biological importance.
4. Excess Heat:
Excess heat, when added to the marine environment, changes ambient conditions, and these changes may be detrimental to the organisms present.
The amount of heat that is detrimental and the extent of the degradation are determined by a number of factors to be discussed later.
The primary source of this heat is, of course, from electrical generating plants, whether they by fossil fueled or nuclear powered.
5. Fresh Water and Brine:
Although fresh water may be in great demand ashore, too much of it in the ocean obviously will produce a marked environmental change within a small area. This, change may be caused by poorly designed storm drainage systems, water diversion networks associated with dams and effluent of some industrial process. Excessive fresh water usually is not a critical problem but it could be one of the effluents were directed into a sensitive area.
The introduction of brine into the marine environment is similar in its effect to that of fresh water except in the opposite direction. The organisms acclimatize to a particular salinity now find themselves in a more saline environment which could cause permanent damage.
Brine is a by-product of desalination plants, but changes in the salinity regime also can produce by-changes in estuarine channel depths necessitated by shipping considerations.
Toxic in-organics are materials commonly used in industry, many of them primarily to control the growth of algae or to destroy pathogens. Chlorine is an excellent example of this. In larger quantities this material is relatively harmless; however, in larger quantities it may be quite destructive.
The key here apparently is how much and how often. There are perhaps 35 to 40 commonly used toxic in-organics and these should be very closely controlled by the user.
The toxic organics are the most disturbing of the modern day chemicals commonly discharged either purposefully or accidentally into the marine environment.
These include the biocides such as fungicides, herbicides, insecticides, rodenticides, and also the additional organics including halogenated hydrocarbons, petroleum and industrial chemicals.
The most disturbing toxic organics are the pesticides such as DDT and ketone which have the unfortunate characteristic of being more soluble in oil than in water so that they tend to collect within the fatty tissues of marine organisms.
They are also very stable compounds which do not deteriorate very easily over a long period of time. These find way into the ocean both as manufacturing effluent and as runoff after utilization.
Perhaps the most distributing aspect of these toxic organics is that there are hundreds available with many more being produced by the chemical industry without any real knowledge of their long-term effects.
Although petroleum may be classed as a toxic organic, it is a naturally occurring material and is biodegradable, given enough time.
Petroleum in its natural state is a very complex organic material containing a large number of separate compounds, each of which seems to have its own effect on the biosphere. These effects are not too well known and opinions within the scientific community range from one extreme to the other with respect to the toxicity of the material.
It is an aesthetically displeasing of nothing else. Petroleum finds its way into the marine environment due to accidents such as tanker damage or transfer loss, natural seepage, offshore production losses, losses associated with refineries, from runoff originating as drippings or disposal of used automobile lubricants, and unburned hydrocarbons emitted into the atmosphere as internal combustion exhaust.
Nutrients are what are commonly called fertilizers, those chemicals required by plants. The most common of these are the compounds of nitrogen and phosphorus. They exist in the natural environment at all times and some of them are recycled naturally by decaying living organisms.
However, the activities of man have added to the total nutrient load of almost all coastal areas. When nutrient levels get out of hand, plants grow unchecked so that decaying plants exists in such great numbers that the oxygen supply becomes rapidly depleted.
These nutrients are present in domestic sewage effluents, agricultural runoff, and the little understood but apparently important non-point source runoff from urban areas.
Radioactive materials are not only discharged to the marine environment by nuclear power plants, fuel production and reprocessing plants, and uranium activities such as the burning of coal, when coal is burned it emits radioactive particles to the atmosphere which are then washed into the sea at a greater rate than any known nuclear power plants at this time.
Other sources of radioactivity are the natural background, weapons testing, mine drainage, accidental spillage, and a few isolated industries.
One of the partially unsolved problems associated with the use of nuclear energy for electrical power is the long-term storage or disposal of spent fuels.
This storage must be in an area such that there are no pathways back to man, and deep oceans have been suggested as meeting this criterion.
10. Oxygen Demand:
Oxygen demand materials are those which require oxygen for degeneration and therefore steal oxygen which would normally be utilized by marine animals. Thus, if too many oxygen demand materials are placed in the marine environment, the animal population will be markedly decreased due to the lack of oxygen.
Sewage sludge and any other organic waste materials, even that resulting from excessive plant growth due to an oversupply of nutrients are examples of common oxygen demand materials.
11. Acids and Bases:
The discharge of acid and bases to the marine environment can be quite disturbing to the natural ecological balance of the systems. The normal pH of oceanic water is somewhere around 8.0, slightly basic.
This is maintained by the carbonate system wherein carbon dioxide is moved back and forth through a chemical reaction to bicarbonate and carbonic acid. If a large amount of acid or base is introduced into the system, the carbonate reaction will be offset and an important element of the environment will be affected.
In addition, there are large synergistic effects associated with pH. Most toxic materials, for example, increase their toxicity under condition of low pH.
The sources of acidic or basic material are primarily industrial with some of this material reaching the marine environment from accidental discharges and the rupturing of tankers.
12. Aesthetic Considerations:
Aesthetically displeasing materials include all the stuff one finds in the ocean that is unpleasant to look at or to smell. Tar balls, floatables, gas (often hydrogen supplied) producing materials, and coloring agents are some examples of pollutants affecting the sense, although in some cases these materials present no real threat to the ecology of an area, when the area is being used for recreation, the quality of the surroundings becomes very important.
Thus, even though an aesthetically unpleasant area may still be useable for many activities, it is one which probably generates the most public response because no special instruments are required to measure the degradation; it is obvious.
We thereafter find that aesthetic conditions very often are more important to the average person than those that may be more damaging from an ecological point of view.