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Quality -> Chemical composition -> Micro components -> Mercury



General characteristics

Mercury is rarely in elementary conditions. It occurs together with sulphur. The main ore of mercury is cinabarite (HgS). It is using in laboratory work (thermometer, barometer and instruments) and in bulbs with mercury vapour, mercury switches and advertising signs. Synthetic organic and inorganic salts of mercury are using industrially and commercially.  The main usage of mercury is in electric equipments. It is using in electrically production of chlorine, amalgams for teeth and as raw material for many mercury compounds. Natural source of mercury in environment is evaporation from Earth crust. Elementary mercury is rare and indissoluble in water. Because of that, toxic of mercury has small attention in water quality until 1950. Soluble salts in water are salts of mercury (I) and mercury (II). The most important salts are HgCl2, HgCl, Hg(ONC)2 and HgS. Organic salts and organic compounds of mercury are the basic shapes of mercury in water. Mercury concentration in soil is 3-300 ppb. Metallization of inorganic mercury are happening in clean water and seawater, but all mercury in pure drinking water is in form of Hg (II). Because of that, there is not direct risk from loading of organic compounds, especially alkyl-mercurate. But still there are real possibilities of transformation in inorganic mercury (WHO, 2004).

Origin in water

Mercury occurs in inorganic shape in surface waters in concentration below 0,5 mg/l and 4% of these waters are with  concentration above 10 mg/1 ( small lakes and reservoirs). Seawaters have 0,03-2,0 mg/1. Underground waters have low concentration of mercury (0,1 mg/1).  

Medical aspect

Negative effect 

Mercury is loading in organism mostly with food, and with drinking water in small quantities. Poisoning with mercury can be acute and chronic. Acute rarely originates from drinking water, except in special situations. Chronic poisoning manifests with overstrain, mental breakdown and gingivitis. The main organs of inorganic mercury are kidneys with neurology and kidney stumbles. Compounds of methyl- mercury are very toxic for central nerve system, and they are also the main source of environment pollution.

Maximal allowable concentrations 

According to recommendations of EU (Directive 98/83/EC) and in our rules for drinking water (Sl. list SRJ 42/98) limitary value for mercury is 1 mg/1.


 






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