Xi'an City Dust, Environmental Pollution And Environmental Quality Evaluation

The pollution of citydust can be shown in two aspect: pollution of grain and pollution of heavy metal. The grains of citydust are not only pollutants, but also the medium of pollution of heavy metal.This paper begins by studying the connection of citydust and suspending grain, studying their mineral composition to know about source of substance; studying their distribution of diameter of grain to know about the pattern of grain's carry and deposition; studying their character of element of heavy metal to know about their correlation. Basing on the factors mentioned above, we put forward the basic mode of carry and cycle of citydust and do its classification. This in turn accounts for the correlation and similarity of citydust and suspending grain.To study pollution of heavy metal in xi'an city, we start by researching the character of environmental geochemistry of citydust. We research environmental background value of heavy metal of citydust, know its distribution in xi'an city, divide abnormality of environmental geochemistry, find out its overall pollution of heavy metal finally. Based on national standard of environmental value of the soil, we constitute standard of environmental value about element of heavy metal of citydust.Based on standard of environmental value about element of heavy metal in citydust mentioned above, we utilize the method of index and assess environmental value about element of heavy metal in xi'an city. The result shows: the citydust in xi'an city has all been polluted by heavy metal, in most areas the pollution being light; the mediate pollution being little; in very small areas the pollution being heavy. The most important pollute element of heavy metal in xi'an city causing environmental damage of citydust is cadmium; The less important pollute elements are copper, lead, zinc, chrome and silver. The pollution caused by arsenic is very small, which just makes small areas polluted in xi'an city.