Effects Of Cadmium Contamination On Nitrogen Transformation, Leaching And Nitrous Oxide Emission Of Vegetable Soil

Soil cadmium pollution is increasingly serious, vegetable suffer cadmium pollution hazards because of the locations and production, and vegetable production safety is difficult to guarantee. At the same time excessive fertilization of vegetables resulting in frequent soil nitrogen enrichment, which guarantees good vegetable production has brought many problems. Therefore this study explored different levels of cadmium contamination; selected the different levels of nitrate accumulation of three vegetables in the soil-vegetable nitrogen transformation system, and examined nitrate leaching and nitrous oxide emissions. Main points of vegetables, soil and leaching liquid, atmospheric four parts to determine the various nitrogen forms, explore the cadmium pollution of nitrogen in soil and vegetables in the system migration and content change, used to guide the vegetable production safety. The results were as follows:1. The study explored the effect of on vegetable biomass, biomass accumulation, total cadmium content of the soil and vegetables. The results showed: With cabbage biomass increased to a maximum with the0.5mg。kg-1and5mg.kg-1Cd addition. The maximum yields were110381kg.ha-1and90159kg-ha-1for the high and low N accumulated varieties, respectively; with radish biomass increased to a maximum with the0.5mg.kg-1and1mg.kg-1Cd addition, the maximum yields were133218kg.ha-1and74943kg-ha-1; with eggplant biomass was inhibited with increased Cd lelves. the resistance to cadmium of varieties are L> H species, while promoting the accumulation of dry matter content. The biomass and dry matter accumulation of eggplant decline was significant at5mg.kg-1. Cadmium accumulation in three vegetables decresed in the order: cabbage> radish> eggplant.2. The study explored the variation of cadmium contamination, the total nitrogen and nitrate nitrogen content in vegetables and soil. The results showed that nitrate accumulation increased with Cd application reaching a maximum at either0.5or1.0mg.kg-1Cd application, and then decreased again at thel.O or5.0mg.kg-1Cd application. The content of nitrate and ammonia nitrogen in the soil increased with the level of cadmium contamination, and were significantly increased with increased levels of cadmium contamination. While no significant changes on the content of total nitrogen in vegetables and soil. But significantly affected the amount of its total nitrogen accumulation.3. The study explored soil nitrate leaching content under cadmium contamination. With the low range of cadmium contamination, concentration increased soil nitrate leaching fluid, along with the increase of cadmium concentration was increased after the first lower trend in the level of Cd contamination0.5mg.kg-1and1.0mg.kg-1reaches the maximum, further increasing nitrate leaching from soil contamination.4. The study explored the variation of soil nitrous oxide emissions under cadmium pollution. The results showed that: With the passage of time, all treatments showed similar trends in N2O emissions, the size of N2O emissions varied between treatments. During the growth of cabbage, at low Cd level promoted N2O emission rate a significant increase, during the growth of eggplant, with the varieties L44, N2O emission rates increased with Cd application up to a maximum with the1.0mg.kg-1Cd treatment. There was no effect of Cd on nitrous oxide emission with radishes. The daily N2O emissions and total emissions had the same trend with emission rates of the three vegetables, indicating that with the increasing of planting times and Cd leaching, the content of cadmium in soil reduced significantly, the effect of Cd contaminated soil to N2O emissions influence became waning, nitrous oxide emissions is no longer a significant difference to this article radish cultivation period.