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The hyperaccumulators screening of Cd contaminated soil

Author: DongLinLin
Tutor: ZhaoXianGui
School: Shaanxi Normal University
Course: Environmental Science
Keywords: Phytoremediation Hyperaccumulators Cadmium
CLC: X53
Type: Master's thesis
Year: 2008
Downloads: 408
Quote: 4
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Abstract

In recent years, the soil heavy metal pollution problem caused by the widespread use of chemical fertilizers and pesticides and sewage irrigation, has gradually become one of the hot issues of the attention and study of environmental scientists. Soil heavy metal pollution has a hidden lag, the cumulative characteristics, combined with the complexity of the process of governance, Therefore, the harm caused by heavy metals in the soil than on the atmosphere, water pollution is more serious. The soil is the main place for people to agricultural production, soil pollution directly relates to the safety of the food chain and human health, it is self-evident, research and management of soil heavy metal pollution is of important theoretical and practical significance. Compare physics, chemistry, bioremediation method, it is often a safe and low-cost biological restoration techniques are more interested. The phytoremediation technology developed in recent years is a safe, low-cost green remediation technology, favored by the majority of environmental scientists, especially suitable for use in developing countries to adopt a new technology with broad application prospects. In view of this, on the basis of domestic and foreign research, select predecessors had not studied 22 species of plants, set different concentrations of cadmium contaminated soil potted simulation test, calculate the plant through the determination of the different parts of the plant biomass, cadmium content parts of the enrichment factor, the quality of the transfer coefficient and plants in different parts of cadmium, analysis of plant absorption of cadmium, enrichment and transport capacity of the strength and range of situations. Study on the correlation analysis between the enrichment factor, transfer coefficient and cadmium concentration, the concentration of cadmium in the soil enrichment plant, the degree of influence of the transit cadmium. The main findings are as follows: (1) the concentration of cadmium in the soil to plant biomass different plant species. Roughly 22 species tested the performance of the following three rules: such as the test of the wild carrot, Humulus, Abutilon, Orychophrogmus, rape, yellow heart black biomass in the low cadmium conditions (soil concentration of cadmium less than 50mg · kg ^{-1 ) will increase with the increase of the concentration of cadmium; underground part of the ground portion of the Amaranth, endive in high concentrations of cadmium (cadmium concentration in soil is higher than 75 mg · kg ^{-1 ) environment, the biomass with the increase of the concentration of cadmium in the soil and reduced; Mandala, cocklebur biomass in high concentrations of cadmium (higher than the concentration of cadmium in the soil the 75mg kg ^{-1 ) environment is still increasing. (2) produce toxic effects of cadmium on the different types of plants critical concentration difference. Such as the poisoned water spinach critical concentration of 25mg · kg ^{-1 , plum beans, wild sorghum poisoned the critical concentration of 50 mg · kg ^{-1 . (3) plant absorption of cadmium showed the following characteristics: (1) does not absorb or less absorption of cadmium. This experiment, only safflower shamrock exhibit this characteristic. Safflower Oxalis grass and underground parts of the cadmium content in the soil cadmium concentration of the highest 125mg · kg ^{-1 only 20.13mg · kg ^{-1 9.64mg · kg ^{-1 , and any cadmium levels are not showing symptoms of poisoned safflower shamrock has a strong tolerance to cadmium. (2) underground part of the enrichment of a relatively large amount of cadmium, the aerial parts of lower cadmium content. Such as sesame aerial parts of the cadmium content in soil cadmium concentration of 125mg · kg ^{-1 reaches its maximum only 13.77mg · kg ^{-1 , the enrichment factor of 0.28, The underground part of the cadmium content the maximum compared 231.32mg · kg ^{-1 , the enrichment factor of 1.85, the transfer coefficient is 0.06. See foxtail, Humulus, velvetleaf, green foxtail, plum beans with sesame Cadmium absorption characteristics similar to wild sorghum. (3) on the ground and underground parts of the cadmium content is higher, the cadmium content of the body also showed an increasing trend with increasing concentrations of cadmium in the soil, plants can grow normally do not exhibit symptoms of poisoned. As black yellow heart, when the concentration of cadmium in the soil below the 50mg · kg ^{-1 , the aerial parts of the cadmium content is less than 100mg · kg ^{-1 , but enrichment greater than 1; when the concentration of cadmium in the soil in turn increased from 75mg · kg ^{-1 100mg · kg ^{-1 , 125mg · kg ^{-1 , corresponding to the cadmium content of the aerial part of 106.44mg the kg ^{-1 , the 165.79mg the for · kg ^{-1 144.72mg · kg ^{-1 , more than cadmium hyperaccumulators (above-ground part of the cadmium content of 100mg · kg ^{-1 ) standard, the enrichment factor were 1.42,1.66,1.16 are greater than 1: transfer coefficient, respectively 0.89,0.94,0.60, are less than 1. Visible, yellow heart black has good cadmium accumulation, enrichment capability, but poor transport capacity of cadmium. (4) the size of the plant biomass to a certain extent affect the absolute number of plants to absorb cadmium. Calculates that in each treatment concentration, the largest spider plants of 22 species of the test organisms, the quality of the body of cadmium is the highest. The Chlorophytum aerial parts of the quality of the cadmium in the test concentrations of 0.170 to 0.325mg, the cadmium content of the body as 45.18 to 65.38mg · kg ^{. -1 , did not reach the cadmium hyperaccumulators standard, the test filter out the yellow heart black and Datura the aerial parts of the highest cadmium content respectively 165.79mg · kg ^{-1 and 115.02mg · kg ^{-1 , but the highest quality of the aerial parts of cadmium were 0.029mg 0.077mg, far below the quality of cadmium in Chlorophytum aerial parts of other plants as well. The size of its plant biomass had a greater influence in the absolute number of absorbed cadmium. (5) different types of plant Cd uptake by the existence of an accumulation of the highest concentration, the concentration of cadmium in the soil to achieve this value, the plant Cd uptake by the strongest, best repair effect. The test filter out two cadmium has a strong absorption capacity of the plant: yellow heart black and Mandala, the cadmium content of the aerial parts of cadmium concentration gradient in the experimental design, the concentration of cadmium in the soil of 100mg · kg ^{-1 , are up to. This shows that the plant in a suitable concentration of Cd uptake by the best performance the repair effect will be reduced when the concentration of cadmium in the soil below or above this value. (6) from the influencing factors of plant species is a key factor that decided to plant uptake of cadmium ability, plant the seed crystal differences in the level of cadmium concentration on the ability of plants to absorb the impact of prisoners. Soil, climate, environmental factors affect plant growth conditions and thus indirectly affect plant Cd uptake by. (7) a comprehensive comparative analysis of the test 22 the cadmium content of the aerial parts of plants, enrichment factor and transfer coefficient, and as a screening hyperaccumulators and measurable indicators of the strength of the absorption capacity of plants to cadmium and found a plant belonging to cadmium hyperaccumulators, but yellow heart black and Mandala Cd uptake by the strongest of the 22 species, followed by eggplant, endive, rape, Bidens parviflora, wild carrot, water spinach, amaranth, parsley, wild sorghum, Abutilon, spider plants, autumn purple beans, cocklebur, Zhuge dishes poor absorption capacity, sesame, Humulus A.aequalis, safflower shamrock, plum beans, The Setaria enrichment worst.}}}}}}}}}}}}}}}}}}}}}}}}

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CLC: > Environmental science, safety science > Environmental pollution and its prevention > Soil Contamination and Control
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