FHSST Biology/Contents/Index/ES/Human Influence/Land
Creation of derelict land.
This is land damaged by industrial or other development so that the land is incapable of beneficial use without treatment. Mining is the main cause of derelict land. Industrial processes such as smelting also cause derelict land. Derelict land may contribute to dust, soil erosion and the subsequent siltation of rivers. Treatment of derelict land is typically expensive.
Many organic wastes may result in the exposure to the environment to a certain element that is usually a limiting substance that is biologically important to certain species. For example, sewage which causes outbreaks of cholera, typhoid and dysentery. Treatment of sewage water should ideally kill the agents of the mentioned ailments. The level of sewage contamination is usually indicated by the concentration of Eshcherichia coli, which is a harmless bacteria but a good indication of sewage contamination.
More phosphorus is added from ‘hard’ synthetic detergents whose foaming reduces photosynthesis and inhibits the oxygenation of water.
Fertilisers are applied in large amounts to crops in modern times, releasing large concentrations of nitrogen and phosphorus into the environment. Causing the eutrophication of fresh waters. Nitrates entering the ground water may also metabolic disorders in domestic animals and children if used for drinking. Domestic livestock produce a lot of waste including sewage waste, much more in fact then their human owners.
The industrial production of lead increased in the 1940’s when lead was first used as an additive in petrol. Most lead produced is now used in this way (modern times?). Lead released into the atmosphere has a residue time of about a month before falling out. The concentration of lead is highest near highways and smelters, but the atmospheric form ensured a wide distribution. It has been shown that there is an accumulation of lead in the Greenland ice cap. Lead poisening has been implicated in causing mental imparement in humans.
Mercury is used in the production of chloride and caustic soda, and as a fungicide. There are two pathways in which mercury and contaminate the environment. The first is the contamination of food, mostly grain, which can cause the death of animals and man. The contamination of water with mercury causes the uptake of mercury in fish.
Waste heat- relecvance to chapter 2 section 3: commonly by power generating plants – e.g. waste heat in Lake Antario (Canada) – hot water can cause changes in biota. A body of water at 30 degrees is essentially a biological desert and many game fish require temperatures of < 10 degrees for successful reproduction. A temperature rise of 10 degrees will double the rate of many chemical reactions and so the decay of organic matter, and the solution rate of salts are all elevated by heating. The metabolic rate of animals is increased and so they require more oxygen which, however, is lower in concentration and the require higher temperatures.