植物修复重金属土壤污染.ppt

植物修复重金属土壤污染.pptPhytoremediation of cadmium pollution in soil
环科1101
李康楠
11320120
Background
Soil heavy metal pollution is refers to the proportion of greater than 5 metals or pounds in the soil environment caused by pollution. At present, the Hg emissions about 15000 tons per year on average, million tons of Cu, Pb, 5 million tons of Mn 15 million tons, ten thousand tons of Ni100. In our country by cadmium, arsenic, chromium, lead and other heavy metal pollution of cultivated land area of nearly 20 million hm2, about 1/5 of the total cultivated land area.
1 . Soil heavy metal pollution sources
Heavy metal concentrations in soil by the dual effects of the natural soil conditions and human activities. Generally, under the condition of low concentration of heavy metals in natural soil, but in recent decades, human activities greatly contributed to the accumulation of heavy metals in soil.
Pollution of the soil
Unreasonable use of agricultural inputs
Solid waste
Sewage irrigation
图1 土壤中重金属污染来源
Atmospheric natural sedimentation and precipitation
Soil cadmium es from the following aspects: :
The harm of cadmium
Cadmium is a kind of grey metal, insoluble in water, the density of g/cm3, melting temperature ℃, boiling point of 767 ℃.
Metal cadmium toxicity was low. But its chemical toxicity is very large. Cadmium in human body savings effect, latent lang but for 10 to 30 years. It is reported that when cadmium in water more than mg/L, residents drinking water for a long time and containing cadmium substances from food intake, can lead to "bone pain disease".
Accumulation of cadmium in soil
Cadmium in soil accumulation of 0 ~ 15 cm. In the soil mainly CdCO3, Cd (PO4) 2 and Cd (OH) 2. Give priority to with CdCO3 again among them.
Due to cadmium can't be in the soil microbial degradation, half-life more than 20 years, as a result, the pollution is the accumulation of the irreversible process.
The mobility and transfer of cadmium in the soil
Heavy metals c