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RECEIVED ON
DEPT. OF LOCAL GOVERNMENT AND THE ENVIRONMENT
When we acquired the land and the pond in 2002 we did not appreciate the importance of clean water for wildlife. The Bride hills are generally sandy and there is little clean flowing water in the area. This expanse of water is no different and like many dubbs had been used for dumping rubbish up to the early 1970's. Over the past 4 years we have spent many hours clearing and tidying the area and the impact has been considerable. During the summer months all forms of wildlife use it on a daily basis. Hundreds of trees have been planted and although we intend to stock the land we will not be using or indeed doing anything that may contaminate the water. However we do have a problem as the days lengthen and the amount of sunlight increases. The water becomes stagnant as there is no natural flow of water passing through the pond. It is purely dependent upon the run off from the surrounding hills when it rains. There are a number of solutions to this problem however, all but one have an impact on the environment in terms of the energy they use and that is the reason why we want to install a windmill in order to aerate the water. These are used around the world as there is no sound pollution owing to a rubber diaphragm and all that is required is a gentle breeze. The proposed site means it will be barely visible from the road. It will also be painted green.
Detailed below is a full rationale for aeration that we have put together. The information has been supplied by a number of different sources and we hope it will support our planning application.
There are many ways in which to aerate a body of water. The main objective to using an aeration system is to provide sufficient dissolved oxygen into the water column - oxygen is the single most important water quality parameter. The sufficient amount or oxygen varies from pond to pond or lake to lake. Much of it centres on the biological oxygen demand (B.O.D.) and water temperature. All living organisms in an aquatic ecosystem need oxygen. Although fish consume oxygen from the water column, their excrement asserts a higher B.O.D. As faeces and other organic litter builds up on the bottom it forms high organic sediment. Micro-organisms, on the bottom of the pond, feed upon this organic matter and subsequently use up the available oxygen. During night time hours plants and algae further reduce the available oxygen.
Many people ask the question, why was my pond or lake crystal clear and free of weeds and algae 20 years ago? The answer to that question is lengthy, most likely nutrient loading is the cause. Decayed weeds, algae, goose manure, and expanding human population contribute to the cause. As more people build homes in a watershed, (all the surrounding land that empties its surface water into a water body), they create erosion problems, and add fertilisers to their lawns. Septic systems fail over time, and leech nutrients into the watershed. These are just a few of the ways a lake or pond can be impacted.
As man's activities bring more and more nutrients into ponds and lakes, the natural production of oxygen and nature's cleansing action have not been able to keep up with the increase. Although added nutrients have increased the ageing of ponds and lakes, the use of forced air aeration has proved effective in prolonging their natural life cycles. The surrounding agricultural land is intensively farmed and therefore by supplying the water with greater amounts of oxygen, aeration systems can slow down the natural ageing process. Increased plant growth resulting from greater amounts of nutrients cause ponds and lakes to use more oxygen in the decomposition of dead plant life. If the bacteria breaking down the organic matter use too much of the water's oxygen then there will not be enough oxygen for fish life. A proper aeration system provides adequate oxygen for both the increase in decomposition and for fish life.
Aeration takes advantage of nature's own beneficial cleansing process. The only difference is that the natural action is accelerated. The aeration system is based upon the principal of inversion, the complete rolling over of a body of water. Inversion is the natural cleansing action of a water body. This process takes place in the spring and autumn when the cooler surface water is heavier than the bottom water and sinks. This is nature's own way of providing oxygen to the water at the bottom and thus removing toxic gases. As more nutrients enter the water, this natural twice a year process is not capable of keeping up with the increase. As the water is inverted oxygen is pulled to the bottom and toxic gases are blown away at the surface. Again, dissolved oxygen at the bottom is the single most important water quality parameter. Aeration systems rely on the same principals of turn over but on a continuous basis. As bubbles rise from the diffuser, bottom water is pulled to the surface. Surface water then replaces the bottom water. Many years of neglect create an unhealthy pond or lake. Aeration must overcome years of organic and nutrient loading and in many instances deal with present loading. The turn around will be gradual. It helps to implement a watershed program that limits present and future loading. This is not easy, but many private individuals and communities have successfully done so.
Oxygen in ponds comes from three sources - photosynthesis, wind and wave action and diffusion from the air. The most important source is photosynthesis that is the process plants use for manufacturing food. In the presence of sunlight, plants and algae add oxygen to the water as a by-product of photosynthesis. At night or in the winter if the ice is snow-covered respiration of fish, algae and bacteria continues to remove oxygen from the water. If the oxygen concentration gets too low either in summer or winter you can have a fish kill.
With an adequate supply of oxygen in the bottom waters, larger and healthier fish populations can be supported. The area for fish survival is essentially increased. Harmful substances on the bottom that were dangerous to fish are released into the atmosphere. Aerobic bacteria, micro-organisms, invertebrates and aquatic insects that are made possible by getting oxygen to the bottom, providing additional food for the fish and break down bottom organic accumulation.
Often water is murky or discoloured by suspended organic particles or matter. By increasing the amount of oxygen in the water, aerobic bacteria will break down suspended organic particles that can result in increased water clarity.
By providing oxygen to bottom waters, a more complete and rapid breakdown of dying vegetation occurs. The nutrients released by this process are then consumed by living organisms that provide an excellent food source for fish. This means fewer nutrients available for new weed and algae growth.
Biological processes occur within a pond. They are a vast topic. Here are 2 of the most beneficial attributes of aeration. Phosphorus, nitrogen, and carbon cause nuisance algae blooms. Very little phosphorus is needed to support nuisance algae growth. (.03 ppm total phosphorus). Once phosphates enter a pond they are almost impossible to remove. The best option is to bind up the phosphates. Aeration accomplishes this. Phosphates can be bound to cautions (positively charged ions present in the water), only if sufficient oxygen is present (oxidation). Once bound to the cations, the phosphorus is precipitated out of the water column and into the bottom sediment. The phosphorus is unavailable for algae growth as long as oxygen levels are sustained. Microscopic organisms, predominantly bacteria, decompose organic matter and use available phosphorus for energy and reproduction. They will accomplish these feats aerobically (in the presence of oxygen). Without oxygen, anaerobic bacteria produce hydrogen sulphide (rotten egg smell), methane and ammonia. All of which are unhealthy to living organisms. Bacteria also are important in converting nitrogen ammonia to nitrate. The safe form of nitrogen.
Each aeration diffuser can keep a 10' to 100' diameter area open even in sub zero weather.
By adding adequate air to the bottom waters, decaying organic matter gases can be gassed off. The stagnant rotting egg odours found in many ponds and lakes can be completely eliminated.
Mosquitoes are not currently a problem in the IoM although are now appearing in the south of England. However with climate change appearing to accelerate it is difficult to rule out that this will still be the case in 10 years time let alone 50 of 100 years. Mosquito's prefer stagnant water. Aeration will also increase fish and other invertebrates that feed on mosquito larva.
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