River Brisbane is the longest river in the southeast Queensland of Australia. It originated from the foothills of the great dividing and flows through Brisbane city before releasing its water into Moreton bay. The river was named after Thomas Brisbane, New South Wales Governor, by John Oxley in 1823. The river provided and still provides a main form of transport between the city of Brisbane and Sydney. Before the European settlement Brisbane River was very clean and unpolluted. It was then used as a source of food and also for recreational purposes. For quite a long time the growth and settlement of people around river Brisbane has adversely affected the quality of its water as well as the life that it supports (Straughan 1972 p.93). As the town of Brisbane grew the river became very unclear and polluted and by 1928 the water quality had deteriorated to the extent that it was not safe even for bath.
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However the government of Australia decided to protect the river from pollution and by adopting antipollution acts as well as educating the public on the importance of protecting the environment. The river was used the source for agricultural water and also provided sand used in the construction around the growing city. The river faced so many risks of pollution from the growing industries and from the waster vessels that transported petroleum products and other substances. Nitrogen from sewage treatment and phosphorous from industrial discharge as well as other metals, were and still are among the main pollutants (MacKey, Hodgkinson & Nardella 1992). However the data taken on the nitrogen and phosphorus levels in the river shows that the efforts of protecting the river have bared some fruits. In 2000 the average nitrogen levels were about 2.2mg/l while in 2009 the average level had dropped to 0.5mg/l. A graph plotted for both nitrogen and phosphorous show a decrease in their concentration in the river.
Introduction
For more than 400 million years now, the Brisbane River has been flowing. Its catchments have endured a number of floods and droughts seasons while its origins have continuously shifted as the surrounding land kept changing from time to time. In 1823 when John Oxley entered River Brisbane for the first time, the river was very clean and unpolluted. After a while Oxley realized that the river could be used as a new site for new settlement and through his suggestion, the city of Brisbane was developed alongside the River in 1825. The Brisbane River, whose origin is at the base of Great Dividing Range, has a catchment area of about 30,000km square and it releases its water into the bay of Moreton (National Library of Australia 1988).
The once pure water of Brisbane was mostly used for drinking and for recreational purposes like swimming and the like. However as the city of Brisbane developed, industries started growing in it. At that time industries took the river as an efficient and cheap point for waste disposal. The Brisbane River was the only means of transport between Brisbane town and Sydney until when the road links were established. This river has for long been the most important asset for of Brisbane city as its still used for transportation, recreational and relaxation purposes. For the better part of the twentieth century, this river has been polluted and overused as its basin provided grazing grounds as well as fertile lands for agriculture (Institution of Engineers, Australia, 1986). According to AsiaRooms.com, the river basin also provided suitable catchment areas which could be used for damming purposes.
The river presented several advantages which for the town and its people but the people exploited these advantages so carelessly such that self reparation appeared unfeasible. Today the Brisbane River has undergone considerable modifications to meet the requirements of the city’s population which is increasing. Through diverse public awareness on the need to protect the environment, the river has gained significant political support in form of anti-pollution acts and policies that were adopted by the government (Doyle & Kellow 1995 p.180). Currently the duty of checking pollution levels and water quality of river Brisbane is currently on the Queensland parliament. The parliament has so far made a lot of progress in its efforts of maintaining the quality of the river by establishing two anti-pollution acts.
These acts comprise the 1971; ‘Clean Waters Act’ and the ‘Pollution of Waters by Oil’ of 1973. Due to the current public awareness on environmental protection and by the help of these acts, the quality of River Brisbane has significantly improved although it’s not yet at the safe levels. According to Doyle & Kellow (1995), the River is currently supporting a population of 2 million people while transport and industries and still dependent on the river, which then helps to understand why its pollution level is still above the safe levels (p.180). The aim of this essay is to give a report on the levels of pollution of Brisbane River from the year 2001 to 2010.
For the 150 years that the Europeans have occupation the region, River Brisbane has seen a number of modifications. The river has survived waves of exploration including agriculture, grazing, urbanization and settlement, etc. the urbanization and settlement required flood mitigation strategies and water storage for drinking purposes (Straughan 1972 p.94). Shipping channels and flood prevention measures also needed to be taken as the river was the main means of transport between the city and Sydney. Sand dredging along the river has been the main activity as sand was highly needed for construction in the city. Between the year 1900 and 1970 approximately 12 million cubic meters of sand were extracted from the banks of River Brisbane. Extraction reached its peak latter in mid 70s when about 1.45 million cubic meters of sand were being extracted annually. The extraction later dropped to 1 million per year and eventually ceased in 1996/7.
The riches of the river between mt Crosby and Wivehoe are most pleasing aesthetically because of their cool atmosphere. Between Jindalee and mt. Crosby the river widens and then flows through rural and residential areas. In this area pollution by human beings is very evident and likely. Currently the Brisbane port is accountable for extraction of sand in the lower reaches of the river so as to maintain deep channels for water vessels. This long time dredging has considerably deepened the river hence making its banks quite unstable (Olafson 1978). Strong urban development has been evident throughout the city and on the south bank reach.
As this river proceeds towards the Pinkenba, commercial and industrial areas dominate while further down from Murarie to the mouth, the river passes through mangrove lined region which is dominated by commercial shipping activity (MacKey, Hodgkinson & Nardella 1992 p 418-420). The speed of water in this region is often determined by season. In this region the river reaches its highest flow speed during summer when there is high rainfall while the minimum flow is in winter when rainfall is minimal. Due to the slow flow of water in this region, there is likelihood of pollutants accumulation and overall deterioration of water quality. However this accumulation of pollutants can be cleaned by the release of water from storage dams situated in the river upstream. Wivenhoe and Somerset dams release certain amounts of water that are satisfactory to the water needs of the people of Brisbane. These two dams enable a more even water flow throughout the year thus maintaining and improving the quality of water in the river. The dams are also used as a means for flood prevention by reducing water flow from the range.
Analysis of the past and current pollutants of river Brisbane
According to Connell & Shaw (1980), the major sources of pollutants of the river comprise the many large scale discharge points where wastes from industries and treatment plants discharge into the river (p.356-358). Currently the discharge from sewage is treated to a safer secondary standard with only a small portion of it being left in the primary standard. The small portion of primary standard sewage discharged into river Brisbane does not only contribute considerably to the toxicant load in the river but also to the nutrient load and increased demand for oxygen. This pollution leads to the contamination of fish and other aquatic life by such substances. Sewage discharge around the city of Brisbane is usually chlorinated hence causing a negative impact to the river. The most common discharges to river Brisbane resulted from the highly industrialized section of the river. The city of Brisbane has two main treatment plants for waste water as well as Gibson Island on the Southside and a luggage point on the North side both of which are found at the industrialized section of the river.
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Moreover River Brisbane faces other risks of pollution from the BP and Caltex oil refineries which discharge into the river discharge streams from potentially contaminated areas. Other discharges into the river such as runoff from the urban and industrial parts, and from upstream parts of the catchment, discharge substantial toxic pollutants into the river (Wong & Tam 2005). Sometimes accidents occur resulting to spills of petroleum and insecticides among other substances. This often results to contamination of the river leading to fish death and other water lives. For instance in April 1998, a tanker known as Barrington was docked at White Island in Brisbane collided with a local boat named Austral Salvor. This accident resulted to a spill of 8 tonnes of heavy fuel into the river.
Conclusion
In order to recommend any possible measures that can help improve the quality of River Brisbane one must understand the past and the current pollutions characteristics of the river. In this paper, the pollution analysis of river Brisbane is based on the data provided by Queensland Department of Environment and Resource Management. Nitrogen and phosphorous which are the main pollutants of the river have been measured and their levels in the river minimized. Nitrogen is found in fertilizers and it usually reaches the river when rain water passes through agricultural fields where fertilizer has been applied. It’s also produced during sewage treatment processes. Phosphorous is produced in the waste treatment plants in Brisbane and from confined livestock operations. According to Cambridge Scientific Abstracts (1997), both nitrogen and phosphorous are can be harmful and toxic to aquatic life since their enhance growth of aquatic plants which then depletes the water of oxygen hence posing danger to fish and other organisms (p.35).
The graph below shows the levels of nitrogen and phosphorous in River Brisbane from the year 2000 to 2009. The concentration of these pollutants was measured in milligrams per litre of water.
Fig.1 graph of nitrogen and phosphorous concentration against years
From the graph we see that in 2000 the level of nitrogen in river Brisbane was quite high with more than 2mg of nitrogen in every litre of water. However due to the extensive public awareness and the anti-pollution measures taken by the government these levels reduced drastically between 2000/1 to below 1.5 mg/l. the downward trend in decrease of nitrogen continued until 2008 when the average level was about 0.5 mg/l. in 2009 the levels appeared to be rising again which shows that the government as well as the general public of Brisbane may have relaxed in its efforts to maintaining the quality of the river.
On the other hand phosphorous levels have been low all through with level of below 0.4mg/l in 2000. The phosphorous levels have also shown a general downward trend and show a likely hood of reaching zero levels within the next few years if the same trend is maintained. The analysis of the past and the present pollution situations of river Brisbane indicate the government as well as the local authorities have done tremendous work in controlling the water quality of the river. If the efforts are maintained, the river will reach its old clean levels within a few years.
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