NPS pollution is present on the land, in the air, and in the water.  While one component may not be harmful the combined effects of several can often be deadly to plants, animals, and humans.  The signs of NPS pollution are often not as clear as point source pollution.  Many times the change is marked over the course of several years.  In streams, the pollution can be marked by decreases in fish, insect, plants, and animal populations, increases in sediment on the bottom of streams, and by algae blooms.

     Water chemistry is something that we all deal with on a daily basis.  The chemicals in water can stain our clothing and toilet fixtures, cause our drinking water to have a metallic or off taste, and cause our plumbing and heating systems to clog.

     Water chemistry is also something that affects the fish and insects that live in the water. Changes in chemical balances can cause stress to the fish, insects, and animals that live in the water.  These changes not only can cause stress, they can limit spawning and egg hatches, and in extreme cases, cause fish kills.  By understanding how the different components of water chemistry fit together, we can begin to look at water chemistry and how it affects us and our environment.

• Alkalinity – Alkalinity is the measure of acid-buffering materials that are in the water. Things such as limestone (calcium carbonate, CaCO3) provide an acid buffering effect in streams.  The higher the alkalinity, the more acid (such as acid precipitation and abandoned mine drainage) a stream can handle before the pH of the stream drops. Streams in Pennsylvania typically range from 20 to 200 parts per million (ppm) of alkalinity.  Streams with naturally low alkalinity are especially susceptible to pollution from acid precipitation.  Alkalinity’s biggest effect is to buffer the effects of pH.

The largest problem associated with alkalinity are the two elements that make up  limestone and other rocks, calcium(Ca2+) and magnesium (Mg2+).  When dissolved in water, these two items create what is known as hardness.  Hardness creates scales in heating systems and in other piping utilizing water.

pH ranges of 6 to 8 are the best for most fish and insects in streams.  Fish, insects, and bacteria are able to survive pH’s higher and lower than this, but not for long. Bacteria (insect larvae feed on these) begin to die off below a pH of 5.5.  Insects and other macroinvertebrates begin to die off at a pH of 5 (these feed fish).  Fish are mostly gone at pH’s of 4.5 or lower.  At pH’s of 5 or less, fish hatches are almost nonexistent.

 

Perhaps more toxic than pH is the metals in the water that the acidic pH releases. Things such as aluminum, iron, and sulfur are released because of the acid.  These elements combine with other chemicals in the water to create compounds that are toxic to aquatic life.  These chemicals burn fish gills, eat away at the fish’s protective mucus membrane, and kill the insects and other critters that the fish rely upon for food.

• Phosphorus (P) – Phosphorus is one of the three essential plant nutrients: nitrogen (N), phosphorus (P), and potassium (K). Fertilizer formulas are set up in accordance to these three materials. 10-10-10 is actually 10 parts nitrogen, 10 parts phosphorous, and 10 parts potassium.

Phosphorus occurs naturally in most soils in the state.  Other sources of phosphorus in the water are wastewater treatment plants, roads, detergents, and land erosion.

 

Applications of fertilizers containing phosphorous can also cause excess phosphorus in the soil.  Phosphorus binds to the soil.  When soil washes into the stream, it takes the excess phosphorus with it.  Phosphorus is the lead limiting factor for plant growth in ponds, lakes, and streams.  A plant will use 1 part of phosphorus for every 10 parts of nitrogen.  In normal waters, plants run out of phosphorus long before they run out of nitrogen.

In phosphorus-polluted waters, plant growth isn’t limited by phosphorus.  Algae, plants, and bacteria that use phosphorus and nitrogen in photosynthesis explode, growing uncontrollably.  These then grow to the point where they choke out other plants, fish, and insects.  Certain types of alga that thrive on phosphorus can be harmful to both animals and humans.  The process of choking out and aging lakes is commonly known as eutrophication.

• Dissolved Oxygen (DO) – DO is the measurement of the amount of oxygen that is in the water.  Oxygen enters the water through direct contact with the atmosphere and also through the tumbling action of waves in lakes and riffles in streams.

Cold water holds the most oxygen.  As water temperatures rise, the oxygen holding capacity of the stream begins to decrease.  As streams widen out and slow down, they warm up.  As they warm up, the oxygen capacity of the stream decreases.  So in smaller, faster, cooler streams, fish like trout and insects like mayflies are common.  In larger, warmer streams, you find fish (like bass and catfish), plants, and macroinvertebrates that are especially suited to those environments.

• Temperature – Temperature affects several different aspects of water chemistry and physical attributes (such as ice or steam), the biggest factor being the amount of dissolved oxygen that’s in the water.  It also helps speed up photosynthesis in plants and algae.

Many different things, such as air temperature, sunlight, and shade, affect temperature.  Removal of riparian areas and channelization of streams has created something, called thermal pollution.  The lack of shade and the creation of shallow concrete channels is what causes water temperatures to rise.  This in turn drops DO, the results of which are discussed above.

• Nitrogen (N) - Like phosphorus, nitrogen is a plant nutrient.  It aids in plant and algae growth.  Nitrogen comes from many different sources: from the air, from fertilizers applied to yards and fields, from wastewater treatment plants, and from failing septic systems.

Nitrogen also helps promote eutrophication.  In its nitrate form, it causes something called methemoglobinemia (commonly called blue baby syndrome in humans), which is caused by nitrates being carried by blood cells instead of oxygen.

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