Nutrient pollution refers to a form of pollution in which nutrients, usually nitrogen and phosphorus, are present in a high concentration that is damaging to ecosystems. Nutrient pollution is primarily a problem in aquatic ecosystems, such as streams, rivers, bays, and lakes. It is particularly an issue of concern in lakes and relatively closed or contained bays, like the Chesapeake bay. Nutrient pollution is caused primarily by the over-use of fertilizers in agriculture, or by waste from animal farming operations. The negative effects of this pollution are to disrupt, damage, or destroy aquatic ecosystems, which often can have negative environmental impacts, by destroying fishing industries.
This article gives a brief overview of nutrient pollution, including its causes in agriculture and its effects on waterways and fishing industries. The article concludes with some concrete recommendations of what can be done to prevent this type of pollution, both for farmers, and for concerned citizens.
How does nutrient pollution work?
Nutrients such as nitrogen and phosphorus are essential for all living ecosystems. Phosphorus is present in soils, and typically originates from the underlying rock or geologic substrates. Nitrogen is present in the atmosphere, but only enters the ecosystem through a complex process of nitrogen fixation, which is carried out primarily by certain plants and bacteria. The growth of plants are limited by the availability of nitrogen, phosphorus, and other nutrients, so in agriculture, the yield of crops can often be improved by applying fertilizers containing these nutrients.
Plants, however, will only utilize a certain amount of nutrients; once they have as much as they need, they are then limited by other factors, like the availability of sun or water, and the remainder of the nutrients will remain in the soil, where it leeches out when it rains, and runs off into the water table or nearby streams.
Although nutrients are beneficial to some plants, an overabundance of nutrients can cause problems in aquatic ecosystems, primarily because it can cause algal blooms. Algae, which are fast-growing microorganisms or simple plants, respond to the influx of nutrients by growing rapidly. The new growth can choke out existing plants, cloud the water, and clog waterways. When the algae begin to die, the process uses up dissolved oxygen, and if the algal bloom was big enough, it can create a dead zone. This process is called eutrophication. Eutrophication is primarily an issue in lakes and closed bodies of water, but it also happens in rivers and bays as well. Even in areas where eutrophication does not happen, nutrients can still harm and disrupt ecosystems by altering the balance of the various species.
Impact on the fishing industry:
The issue of pollution caused by runoff of nutrients from agriculture is not just an issue of protecting the environment. This form of pollution has immediate and tangible economic impacts. When an aquatic ecosystem is disrupted, the populations of all animals, including fish, crabs, oysters, and other shellfish, are disrupted. In many cases, such as in the Chesapeake bay, whole fishing industries have been destroyed. Whole towns, reliant on fishing for their livelihood, have been driven to economic ruin as a result of the waning populations of fish, caused in part by nutrient pollution, combined with other types of agricultural and industrial pollution.
Causes of nutrient pollution:
The overwhelming majority of cases of nutrient pollution are caused by runoff from agriculture. The main two culprits are the over-use of fertilizer by farming operations growing crops, and the runoff of waste from animal farming operations, such as pig farms or chicken farms.
Nutrient runoff is a wasted resource:
Because nutrients are valuable inputs into the agricultural process, nutrient pollution involves unnecessary waste, waste of inputs, or a wasted resource which is being discarded. In sustainable farming practices, the farmer will apply only the amount of fertilizer that is needed, and the nutrients will be taken up completely by the crops being grown. In sustainable production of animals, the animal waste will be gathered and used as fertilizer for other crops. For example, traditional farming methods use manure from cows and large animals, as well as chicken and pig waste, to fertilize other crops.
A point for hope:
This last realization is a point for hope. Nutrient pollution is not necessary; it represents an inefficiency. It is a problem that can be solved. But there are other ways in which people can prevent or minimize the effects of this form of pollution. One simple but powerful solution is the creation of buffer zones, wild green spaces, along waterways. By filling the areas along streams and rivers with lush growth of plants, the plants will extract nutrients from the water before it runs into the river, and use it for their own growth. The preservation and restoration of wetlands also has a similar effect, filtering nutrients out of the water, as plants use them for their own growth. By raising awareness of these issues, we can ultimately solve the problem of nutrient pollution.