Rivers and Canals
Rivers and canals are both moving bodies of water, however, unlike rivers, canals are man-made structures that channel water for human use. Canals can be used as water ways to provide a method of transportation, either for goods or people; or they can be used to transport water either for irrigation purposes, or for drinking water for human consumption. Very often canals are constructed to connect different water bodies. Depending on the size of the canal, the method of transport used can vary from small barges, to large ships.
Depending on the area that they flow through, rivers and canals may be exposed to different types of pollutants that may enter the water. Where ships and barges travel through rivers and canals, the water is more likely to become contaminated by oil and fuel spills. Litter and waste may be thrown overboard, thus polluting the water further.
Factories very often discharge their waste products directly into rivers, resulting in adverse range of industrial contaminants entering the system. These can include heavy metals, chemicals, organic and inorganic compounds, oil and petroleum, to name a few. Discharged waste may also include industrial dyes that can increase water turbidity, which could have a negative impact on algal growth and primary production in aquatic systems.
Pollutants originate from two main sources, and are classified according to their point of origin They are either point source pollutants, where the contaminants enter the water directly from the source from an outlet that flows directly into the river or canal at a specific point,or they are non-point source pollutants, which may originate from a point nearby or some distance away, and flow into a river or canal with runoff,rather than being discharged directly into the river or canal. Point source pollutants include factory waste, while non-point source includes pollutants that are flushed into a river or canal with runoff, or by airial drift –including pesticides, debris and sediment, organic matter, animal manure, etc.
Whether pollutants originate from point source or non-point source, they all can potentially effect the quality of water in rivers and canals – and eventually lakes – where they can negatively impact aquatic species, as well as wildlife that consume them or the water, including man.
Furthermore, nitrates and phosphates enter rivers and canals from animal manure and fertilizers used in the production of crops, and to maintain facilities such as golf courses. These can fuel algal growth resulting in algal blooms, which can be toxic to animals and humans.
Rivers and canals can become polluted by contaminants from a variety of sources. These include:
- Chemicals, industrial waste products, and sewage that is discharged into rivers and canals.
- Hazardous toxins, such as pesticides and herbicides, entering rivers and canals from runoff.
- Runoff from urban areas can wash oil, road salt,and other chemicals, as well as litter, off road surfaces and into rivers and canals, or storm water drains may carry these pollutants into rivers and canals from urban areas.
- Land use, such as agriculture, logging and mining, may cause high sediment loads to enter rivers and canals as a result of erosion.
- Nutrient loads may be raised as a result of runoff from agricultural land use as a result of animal manure and fertilizers being washed into rivers and canals. Fertilizers used to enhance sporting facilities such as golf courses and sports fields can also cause excessive nutrient loading in rivers and canals.Litter,especially plastic bags are often washed or blown into rivers and canals.
- Litter not only reduces the aesthetic appeal of rivers and canals, it also limits the potential for utilizing rivers and canals for recreational and tourism opportunities. Aquatic species can fall victim of entanglement in discarded litter, and are especially vulnerable to becoming entangled in discarded fishing line. Animals and birds may mistake small bits of plastic debris for food, which may cause them harm.