The Effect of Nitrates

If your lake or stream tests positive for nitrates, this does not necessarily mean that there is a problem with the water quality. High levels of nitrates in water can create conditions that make it harder for aquatic insects or some species of fish to survive.

Algae and other aquatic plants use nitrates as a source of food. If algae have too many nitrates available, they will grow fast and abundantly. So what is the problem with that?

Large amounts of algae can cause large variations in the amount of dissolved oxygen in the water. Photosynthesis by algae and other plants generates oxygen during the day. However, at night, dissolved oxygen may decrease to lower levels because of higher levels of oxygen consuming bacteria that feed on dead or decaying algae and other aquatic plants.

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Most people who have a well know to test for the presence of nitrates. In drinking water it is much more critical than in your lake or stream. If you drink water that has a high level of nitrates, it can interfere with the ability of your red blood cells to transport oxygen.

Infants who drink water high in nitrates may turn "bluish" and appear to have difficulty in breathing since their bodies are not receiving enough oxygen.

Methaemoglobinaemia is caused by the decreased ability of blood to carry vital oxygen around the body. One of the most common causes is nitrate in drinking water. Controlling nitrate levels in drinking water sources to below around 50mg/litre is an effective preventive measure.* *Taken from the World Health Organization

Why do we need nitrogen? What are the sources of nitrogen? Nitrogen is essential for all living things, this includes both plants and animals. If you look at what makes up DNA in cells and what is found in proteins, you will find the presence of nitrogen. Animals get nitrogen by eating plants and other animals. Plants need nitrogen for growth. Unlike animals, they can’t get their nitrogen by eating proteins. Plants get nitrogen from water and from the soil. They absorb nitrogen in the form of nitrates and ammonium ions.

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Aquatic organisms excrete wastes that contain ammonia. When these organisms die they create ammonia. Different types of bacteria in the water change the ammonia produced during decomposition to produce nitrite which is then converted by other bacteria to nitrate. (NO 3 - )

Although nitrates occur naturally in soil and water, high levels of nitrates are usually considered to be a contaminant of ground and surface waters. Many sources of excess nitrates come from human activity. These can sometimes be traced to agricultural activities, human wastes, or industrial pollution.

Nitrogen based fertilizers are often applied to fields, yards, and golf courses to help with the growth of plants. Manure is also used as a fertilizer to promote plant growth. Rainwater can wash some of these nitrates into streams and rivers or the nitrates can seep into the ground water.

Untreated human sewage can also contribute to nitrate levels in surface and ground water. Leaking septic systems or septic systems that are not functioning properly can be a source of nitrates. And while city sewage treatment plants treat sewage to make it non-hazardous, these plants still some release nitrates into waterways.

Not all excess nitrates are from human activity. If a lake has the presence of large numbers of birds, their excretions that get into the water can create higher levels of nitrates.

Higher levels of nitrates can mean more aquatic plants. An excess in the growth of plants and algae can create an unstable amount of dissolved oxygen.

A fluctuation of dissolved oxygen between daytime and nighttime amounts can create stressful conditions for fish. If they are stressed for a significant part of the day, it will affect their normal eating patterns and their reproductive patterns.

Excess algae or plant growth is a problem for riparians. If you've ever been to a beach where mats of rotting algae wash up on shore or the bottom of the lake is teaming with weeds, it's could be because excess nitrates are available for plant growth.

Taken from: cwh.triplepointwater.comcwh.triplepointwater.com