Abstract:

In this paper,we have studied the relationship of lead and cadmium to the organic

matter, clay content and pH in the paddy soil in the Dongting lake region, Hunan Province

It shows that the content of organic matter has a distinct relationship to cadmium or lead

in soilThe increase in organic matter in soil may obviously lower the content of cadmium

or lead in ionic and exchangeable formAlso, the increase in clay content in soil may

slightly increase the proportion of the content of cadmium and lead in ionic exchangeable

form to the total content of Pb and CdThe lead or cadmium that is adsorbed in the clay

surface may enter into the frond more easily, and would endanger the ecosystemThe soil

acidification may increase the content of cadmium in ionic exchangeable form, which has a

distinct relationship to the pH in soil, and directly results in the increase in cadmium

content in crop, thus it is a good way to avoid ecosystem damage by preventing soil

acidificationThe proportion of the content of lead in ionic exchangeable form to the total

content of lead is distinctly related to the pH in soil; keeping soil pH in a range of less

acidity to alkalescence is a better way to prevent soil acidification or basification in the

heavily leadpolluted areaIt is concluded that the soil organic matter and soil pH are

the most important factors controlling the geochemical behavior of heavy metals

Key words:

Key words: heavy metal element; organic matter; clay; soil pH