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Pollutants in Long Island Sound

The major types of pollutants that affect Long Island Sound are described in this section. We have also included explanations of some of the terms that are often used in discussing water pollution. The Long Island Sound Study has identified the major overall sources of pollutants carried into the Sound as (1) rivers, (2) sewage treatment plants, (3) urban runoff, (4) nonurban runoff.


Nutrients are substances essential to living things. It may seem strange to list them among pollutants, but in excessive concentrations they can create serious problems. Nitrogen, phosphorus, and carbon are the major nutrients for the algae at the base of the food chain in the Sound and are always naturally available from animal waste and the decay of dead plants and animals. Nitrogen has been identified as the nutrient that controls how much algae grows in the Sound. The more nitrogen, the more algae. And following excessive algal blooms comes an overload of dead algae and lowered concentrations of dissolved oxygen, which is used up as the dead algae decay. (Phosphorus pollution has caused similar problems in many freshwater lakes.)

Pure nitrogen is a gas that makes up 78 percent of the air volume, is harmless, and cannot be used as a nutrient by most living things. Only after nitrogen is made water-soluble as ammonia, nitrates, or organic matter from plants and animals is it available as a nutrient. Increasing amounts of water-soluble nitrogen from sewage treatment plants, air pollutants, and other nonpoint sources have led to the serious problem of hypoxia in the Sound.


What usually spoils the pleasure of strolling along the shore? Floatables - we've all seen them. The term refers to any water-borne debris that washes up on the shore. The most common floatables are chunks of plastic, paper, and glass; cigarette filters; plastic cups and utensils; plastic packaging materials; and metal beverage cans. Such items are not only unsightly, but can kill birds, fish, and turtles that swallow them or become tangled in them.

Combined sewer overflows and water from storm drains are the largest sources of floatables in the Northeast. In the worst cases, a long dry period during which litter accumulates on streets is followed by torrential rains that flush debris into sewer systems and forced numerous CSOs. During this period, hospital waste is often observed on the south shore of Long Island and in New Jersey. This observation prompts great public concern and leads to misinterpretation of conditions in some places. Most of the disturbing "medical waste" that has received so much attention along the Sound is either misidentified trash, items discarded by substance abusers, or items such as disposable syringes used at home for insulin injections by diabetics.

Where floatables are concerned, the problem is definitely us. To solve the problem, people must be taught not to drop their garbage on beaches, on streets, down storm drains, down toilets, or overboard. Other remedies are to decrease the volume of floatable waste through recycling, to clean streets and storm drains more often, to send out skimmer vessels to collect floating debris in harbors, and, ultimately, to eliminate combined sewers.


Pathogens are viruses, bacteria, and other microorganisms that can cause diseases. Pathogens enter the Sound in combined sewer overflows, water released by malfunctioning septic systems and sewage treatment plants, and runoff contaminated by animal waste.

Routine analysis of water for the various microorganisms that cause diseases such as diarrhea, dysentery, typhoid fever, hepatitis, or cholera is much too difficult. Instead, analysis is done to detect coliforms. Coliform bacteria are found in the digestive tracts of all warm-blooded animals. The coliforms are not harmful to humans, but because they are always present in sewage and animal waste, they indicate the possible presence of pathogens. When high coliform counts are found in the water, beaches are closed and shellfishing is prohibited. Eating clams, oysters, and mussels from such waters is hazardous because these shellfish are eaten raw (or perhaps improperly cooked). As filter feeders, shellfish process large volumes of water and can concentrate pathogens in their bodies.

Heavy metals

"Heavy metals" are not big chunks of iron and steel. In terms of water pollution, they are the water-soluble forms of certain metals. (These metals are "heavy" in the chemical sense because their atoms are heavier than those of other metals.)

Copper, lead, mercury, cadmium, nickel, chromium, and zinc are some of the heavy metals of concern as water pollutants. One property they share is the ability to be harmful at rather low concentrations. Another is the ability to accumulate in the flesh of animals that consume them and in sediments on the bottom of the Sound.

Copper enters the Sound mainly in water that has flowed through household plumbing. Lead comes mainly from urban runoff over streets and other surfaces exposed to leaded gasoline and paint. Although the use of such gasoline and paint has greatly diminished, much remains in the environment. Heavy metals released during incineration of waste are also washed out of the atmosphere by precipitation.

A bright spot in Long Island Sound pollution studies has been the finding of a gradual overall decrease in heavy metal concentrations in shellfish and in sediments since the 1970s. The shutdown of some nonprofitable, polluting factories, enforcement of the federal Clean Water Act of 1972, and the phasing out of lead from gasoline, share credit for the reductions in heavy metal contamination.

Organic substances

An organic substance is any pure chemical or mixture of substances produced by a plant or animal, or any synthetic substance of related composition. For example, table sugar is an organic substance and so is the banned pesticide DDT. (Table sugar is made of carbon, hydrogen, and oxygen. DDT is made of carbon, hydrogen, and chlorine. All organic substances contain carbon and hydrogen.)

Our society is dependent on synthetic organic chemicals for drugs, cleaning agents, paints and adhesives, pesticides, and raw materials for plastics and fabrics. Most are made from petroleum or its derivatives. Like petroleum, some synthetic organic chemicals are more soluble in fats and oils than in water, a property that makes them persistent in the environment and in the fatty tissue of animals.

The terms "organics" or "organic matter" are also sometimes used collectively for all the waste matter from living or dead plants and animals.

The following paragraphs describe some of the organic chemicals most often mentioned in connection with water pollution. They might enter the water from any of the point or nonpoint pollution sources.

  • PAHs (polycyclic aromatic hydrocarbons): Hydrocarbons are substances that contain only carbon and hydrogen. PAHs are complex hydrocarbons naturally present in petroleum and coal, which can spill into the Sound from barges and industrial activity. PAHs also form when fossil fuels, trees, trash, or charcoal are burned. In this case, they become air pollutants that are washed out of the atmosphere by precipitation. The principal hazard of PAHs is their known activity as carcinogens, that is, as cancer-causing agents. They are, in fact, among the principal carcinogens in cigarette smoke.
  • PCBs (polychlorinated biphenyls): PCBs are a class of compounds that remain of concern as pollutants although their manufacture in the United States ceased in the 1970s. The very properties of great stability to heat, electrical current, and environmental breakdown that led to their widespread use (e.g., as insulators in electrical transformers) have guaranteed their persistence in the environment. In high concentrations, they have caused illness. Their principal hazard, however, is from their gradual accumulation in fatty tissue during long-term exposure to low concentrations and their potential for causing cancer or birth defects. Because PCBs are fat-soluble, their concentration increases more rapidly in fatty fish than in nonfatty fish. Health officials have advised limiting consumption of striped bass and bluefish because of high PCB levels.
  • Pesticides: Any natural or synthetic chemical used to kill a bothersome plant or animal is a pesticide. Each individual pesticide has its own profile of potential hazards and cautions during use. Environmental concerns tend to focus on a number of extremely stable insecticides containing chlorine. The group includes DDT, aldrin, dieldrin, lindane, and heptachlor. Like PCBs, the use of many of these compounds has been halted in the United States, but they persist in the environment. Unlike PCBs, however, their concentrations in fish and shellfish from the Sound are apparently not high enough to be of general concern.
  • Petroleum and its derivatives: It has been estimated that 0.1 percent of the world's annual petroleum production is spilled into the world's oceans. With hundreds of oil barges traveling in the Sound, small spills are inevitable and larger ones are possible. Over time, petroleum evaporates or is broken down by bacteria. In the short term, however, it is deadly for plankton, fish larvae, shellfish, and aquatic birds.
  • Many commercial products used in homes, workshops, and industry contain solvents and active ingredients made from petroleum. Some evaporate quickly, are highly flammable, and are most hazardous during their use. Others, like PCBs or pesticides, are persistent in the environment and may damage living things through low-level, long-term exposure. Marine supplies, including fuel, oils, paints, and solvents, are one easily identifiable source of petroleum derivatives that enter the Sound.

Toxic chemicals

A "toxic" chemical is one that can kill or damage any living organism. The "toxics" referred to in environmental studies are mainly heavy metals and synthetic organic chemicals such as PCBs and pesticides that are slow to break down naturally. Toxic contamination is sometimes detected by analysis for the individual pollutants in water and sediment samples. It is also detected by exposing a variety of organisms (fish, algae, and invertebrates) to the polluted water. The pollutant level is judged by studying the growth, survival, and reproductive success of the exposed organisms.

Enforcement of the Clean Water Act has resulted in a significant reduction in toxic materials entering the Sound on a daily basis. Many toxic materials, particularly heavy metals, remain in the soft sediments of the Sound, however. There are several "hot spots" in which contaminated sediments have been identified as a problem to be dealt with. Most notable is the Black Rock Harbor in Connecticut, where there was once extensive industrial wastewater discharge. Recent studies have found that the sediments are toxic to marine life, although the concentrations of toxics in the water are very low.

Airborne pollutants

An air pollutant becomes a water pollutant when it is washed into the water by precipitation or settles into the water by the force of gravity. Nitrogen and sulfur oxides, which are major air pollutants, are gases produced by fuel combustion. They combine with water in the atmosphere to produce acid rain, which can be harmful to natural ecosystems. Furthermore, the nitrogen-containing substances in acid rain contribute to the nutrient burden in the Sound. Heavy metals and PAH's in fine particles from industrial operations or fuel combustion also enter the Sound from the air.

Soundkeeper, Inc.