دانلود گزارش کارورزی و کار آموزی

چکیده : 

the ultimate goal of soil remediation is to restore soil health. Soil microbial parameters are considered tobe effective indicators of soil health. The aim of this study was to determine the effects of phytoextractionon microbial properties through the measurement of soil microbial biomass carbon, soil basal respira-tion and enzyme activities. For this purpose, a pre-stratified rhizobox experiment was conducted withthe Cd hyperaccumulator Sedum alfredii H. for phytoextraction Cd from an artificial contaminated soil(15.81 mg kg−1) under greenhouse conditions. The plant and soil samples were collected after growingthe plant for three and six months with three replications. The results indicated that the ecotype of S.alfredii H. originating from an ancient silver mining site was a Cd-hyperaccumulator as it showed hightolerance to Cd stress, the shoot Cd concentration were as high as 922.6 mg kg−1and 581.9 mg kg−1at thetwo samplings, and it also showed high BF (58.4 and 36.8 after 3 and 6 months growth), and TF (5.8 and5.1 after 3 and 6 months growth). The amounts of Cd accumulated in the shoots of S. alfredii reached toan average of 1206 g plant−1after 6 months growth. Basal respiration, invertase and acid phosphataseactivities of the rhizosphere soil separated by the shaking method were significantly higher (P < 0.01)than that of the near-rhizosphere soil and the unplanted soil after 3 months growth, so were microbialbiomass carbon, urease, invertase and acid phosphatase activities of the rhizosphere soil after 6 monthsgrowth. Acid phosphatase activity of the 0–2 mm sub-layer rhizosphere soil collected by the pre-stratifiedmethod after 3 months growth was significantly higher (P < 0.05) than that of other sub-layer rhizospheresoils and bulk soil, and so were microbial biomass carbon, basal respiration, urease, invertase and acidphosphatase activities of the 0–2 mm sub-layer rhizosphere soil after 6 months growth. It was concludedthat phytoextraction by S. alfredii could improve soil microbial properties, especially in rhizosphere, andthis plant poses a great potential for the remediation of Cd contaminated soil.