Introduction
My report is about waterway pollution in New Zealand. New Zealand’s waterways are more polluted than you might realise.
95-99% of rivers running through urban and farming areas carry pollution above water quality guidelines.
What is water pollution? The definition of water pollution is the contamination of streams,rivers,lakes or the ocean.
There are 2 types of water pollution, organic and chemical.
Organic pollution is due to bacteria,viruses and microorganisms being present in the water. Excrement, animal and vegetable waste can introduce these contaminants.
Chemical pollution is introduced by nitrates and phosphates of pesticides,animal and human medicines,household products,heavy metals, acids and hydrocarbons used in industry.
In this report I will argue that the way to solve this problem is to implement strategies to prevent contaminants entering the waterways.
Causes
Farm run-off is a big cause for waterway pollution, an example of which is the excess nutrients from livestock. For pasture to grow well nitrogen is essential this comes from clover and other legumes which get it from the atmosphere or fertilisers. Animals intake the nitrogen when they eat the pasture and most of it is released as waste through urine. Urine from cattle adds nitrogen to soil at high rates, so large amounts of nitrogen can leach through the soil and into groundwater. The groundwater can eventually reach streams, ponds or lakes.
Nutrients such as nitrogen (one of the sources of nitrogen in rivers,lakes and ponds is mentioned in the previous paragraph) and phosphorus, can lead to algal blooms. An algal bloom is an overgrowth of algae caused by the excess nutrients mentioned earlier in the paragraph. Algal blooms can cause dead zones. A dead zone is when an overgrowth in algae blocks sunlight from aquatic plant life and consumes the oxygen in the water. The lack of oxygen and sunlight in the water makes it impossible for aquatic life to thrive. Algae blooms can occur when a combination of suitable environmental conditions exist. The environmental conditions include increased nutrients,warmer temperatures,abundant light and stable wind conditions. When the conditions are more favourable for one species it allows for one organism to become dominant and form a bloom.
Another pollutant is sediment. Sediment causes degradation of ecosystems by making the water turbid (cloudy) and smothering natural habitats on banks and bottoms of rivers. Sediment can enter rivers when it is washed down creaks in the forms of soil,gravel and pebbles. This increases after harvesting trees and crops.
Consequences
Consequences for Animals and Plants
When debris accumulates on the surface of the water it blocks out sunlight that plants need for energy.The removal of light from the habitat will prevent plants from photosynthesizing and creating glucose which in turn stunts their growth.
Pollution is causing pH levels to change in water bodies which kills aquatic plants that can not survive in acidic conditions.
‘Harmful algal blooms release toxins that contaminate drinking water, causing illness for animals and humans’
Consequences for Humans
Pathogens (such as e.coli) can occur in waterways from wastewater discharges,leaks and overflows, algae blooms and run-off from live-stock farming. These pathogens can have health risks when the water is swum in or drunk.
Water contaminated with animal or human faeces can lead to gastrointestinal diseases such as salmonella, Giardia, Campylobacter, and Cryptosporidium.
‘The reported health effects of cyanobacteria are varied but include gastrointestinal symptoms (such as diarrhoea, vomiting, abdominal pain), headaches, fever, muscle aches, joint aches, vertigo, influenza-like symptoms, fatigue, drowsiness, sore throats, conjunctivitis (red eyes), blistering around the mouth, itchy skin rashes, hay fever-like symptoms, and various allergic reactions. Conditions such as hay fever, eczema and dermatitis may also worsen and exposure to cyanobacteria may trigger an acute attack of asthma.’
‘Cyanobacteria blooms form when cyanobacteria, which are normally found in the water, start to multiply very quickly. Blooms can form in warm, slow-moving waters that are rich in nutrients from sources such as fertiliser run-off or septic tank overflows.’
Various Solutions
Fencing Streams and Rivers in Agriculture
Fencing close to the water’s edge
Keeping stock away from the waters edge is a good first step to improving waterway and water quality.This is because there is less chance of animal faeces ending up in the water and the stream or river bank is not eroded by the animals which can cause sediment to enter the waterway.
Fencing and leaving a grassed strip
Some plants act as filters for removing sediment, bacteria and nutrients in farm run-off. Some of these plants are grasses, native sedges and rushes. For the most efficiency grass strips that are on flat or wider rolling land should be at least 1-2 metres wide. If the land is steeper the grassed strip needs to be wider. The steeper the land is the wider the grass strips need to be.
Grassed strips also improve water quality.
Fencing stock out of drains, seeps and wetlands
When stock is kept out of drains, seeps and wetlands it reduces the amount of stock lost due to bogging and improves the management of the stock. The exclusion of livestock gives these wet areas an opportunity to function as natural filters and denitrification zones. The benefits of wetland plants growing in these areas are filtering bacteria and nitrogen from farm run-off and improving water quality by trapping phosphorus and sediment suspended in the water.
Reducing the amount of cattle farming
Reducing the amount of cattle farming would benefit the waterways because there would be less nitrogen entering the waterways from the urine of the cattle.It would also reduce the amount of phosphorus entering the waterways because phosphorus is used as an ingredient in the fertiliser that is used on the fields to increase the speed of the grass growth.
Reduced use of fertilisers and pesticides
Reduced use of fertiliser would mean less nutrients in farm run-off. Nutrients in farm run-off can cause excessive growth in aquatic plants slime when carried to waterways. These can lead to impacts on animals like fish and mayfly. Nitrogen excess in groundwater is concerning for the quality of our drinking water.
Pesticides can kill non-targeted organisms and plants. Insecticides are the most acutely toxic class of pesticides, but herbicides can also pose risks to non-target organisms.
Best Solution
Reducing the use of pesticides and fertiliser is the best solution because its low cost is effective and is not difficult to do. And there is no labour requirement. Its cons are that alternatives would need to be found. But it would impact the economy because pesticide and fertiliser sellers would make less money and if alternatives didn’t work as well, crops would be less likely to grow and grow slower which could cause a food shortage.
Conclusion
My conclusion is that the main cause of waterway pollution is agriculture. The nutrients in agricultural run-off which come from fertiliser can lead to algal blooms which can be harmful. The consequences of agriculture include pathogens, death zones and cyanobacteria; these all affect the quality and contamination of water. I think the best solution would be to use less fertiliser. By doing this the number of nutrients entering streams and rivers from agricultural run-off would decrease. The second-best solution would be fencing off streams and rivers that run through agricultural land. Fencing of the streams and rivers in agricultural land would reduce the amount of faecal waste entering the streams and or rivers directly.