Mercury (element) is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in scientific research applications and in amalgam for dental restoration in some locales. It is also used in fluorescent lighting. Electricity passed through mercury vapor in a fluorescent
The Broads practices and sewage disposal in the 1950s and 1960s released high levels of phosphorus and nitrogen into the Broads, causing eutrophication. Algal blooms can be toxic, posing a health risk to humans and wildlife. Mass decay of plant matter removes oxygen, damaging fish stocks, preventing recreational fishing. The loss of larger plants and reed fringes in eutrophic waters increases erosion of banks and the buildup of sediment on lake floors. This impedes navigation and requires costly dredging to remove. The beauty of the area is damaged by eutrophication, which is detrimental to the tourism industry. The Broads authority and Environment