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Effect of Sewage-sludge on Growth Pinus Sylvestris Var. Mongolica Seedlings and Amendment of Aeolian Sandy Soil

Author: LiXue
Tutor: TangFengDe
School: Liaoning University
Course: Environmental Science
Keywords: Sewage sludge Pinus sylvestris var. mongolica Aeolian sandy soil
CLC: X173
Type: Master's thesis
Year: 2011
Downloads: 78
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Abstract

Sewage sludge is the left solid waste after treatment sewage sludge by treatment plant, including a lot of nutrient elements, harmful bacteria, microorganism and various heavy metals. The original disposal ways mainly is piled up, this kind of means not only occupying land but also polluting environment. At present, sewage sludge reuse has been a main ways of sewage sludge treatment of disposal global recognition, in which sewage sludge used in land is sorts of the most important way in all means of sewage sludge reuse. The studies have shown that both at home and abroad, the sewage sludge can improve soil fertility, promote the growth of plants, but the poisonous and harmful constituents of sewage sludge （mainly the heavy metals in the sludge） restrict the use of land utilization, mainly two aspects: one is that if sewage sludge treated in edible plants, heavy metal will entering the food chain, harming human body health; second is that the harmful constituents of the sludge may into underground, affecting the safety of groundwater.Pinus sylvestris var. Mongolica is the main reproducing tree species of desertification forest in the north of China for windbreak and sand-fixation, growing rapidly in cold, drought and infertile desert soil. But the drought and infertile are also the important factors to Pinus sylvestris var. Mongolica in desertification.Therefore, a field experiment has been taken with the aeolian sandy soil, sewage sludge and 2 years Pinus sylvestris var. Mongolica seedlings for find out the influence of Pinus seedling growth, the amendment of Aeolian sandy soil and the infiltration condition of heavy metals in soil at different treatment of sewage sludge. All the consequence will provide the theoretical basis for the feasibility recycle utilization as resource on woodland in sandy soil. The primary results which have been got are:（1） Sewage sludge application had a significant influence on the ground biomass and the underground biomass of Pinus seedlings, tendency is increases then reduce. The sludge treatment of biomass weight increment is larger than CK processing; the biomass weight increment larger at 15 kg, 10 kg sludge treatment with peak; Under 20 kg, 25 kg processing biomass increment although higher than CK processing, but from 20 kg sludge treatment after, biomass increment decline, has shown that the toxic of sludge. The height, stem diameter, leaf length and leaf area of Pinus seedling in the sludge concentration processing also showed higher than CK processing, 10 kg, 15 kg processing are better, but from 20 kg processing after, sludge Pinus seedlings obviously shows the inhibition.（2） Overall, the application of sewage sludge in that the content of chlorophyll Pinus seedlings showed increased and then a downward trend, spikes in 15 kg processing; the influence more remarkable to chlorophyll a than chlorophyll b by sludge treatment; due to the content of chlorophyll far higher than the content of chlorophyll b, the content of chlorophyll a + b also show first increase then reduced, after 20kg sludge treatment showed inhibitory effect.（3） Application of sewage sludge can significantly improve the content of nutrient elements in sandy soil; With the increasing amount of sludge, organic matter, phosphorus and nitrogen, phosphorus, rapidly-available phosphorus increased significantly; prime, the increase mainly concentrated expression in 0-20 cm soil place; with time, in different variation in content of the index is mainly manifested in the 20-60 cm soil, content change is seldom in 0-20 cm soil; among them, the highest available nitrogen and organic matter content focused on 20-40 cm soil; the content of phosphorus in deep soil little change.（4） Application of sewage sludge can effectively increase the content of the metal Zn, Cu and K in soil, and as sludge quantity increases; the content of K and Zn are mainly manifested in the increase in 0-40 cm soil; the increase of the content of Cu mainly in 20-40cm soil; the content of K、Zn、Cu did not change obviously with the different treatment of sludge in 60^-100 cm; application of sewage sludge for the content of harmful heavy metal Pb and Cd has no obvious rule influence; compared with CK processing, very small amounts will increase of the content of heavy metal Pb and Cd in soil; the D-value of Pb content between the sludge processing to CK processing is 0.103～0.172μg·g^-1; the D-value of Cd content between the sludge processing to CK processing is 0.013～0.019μg·g^-1, and the highest value is 0.024μg·g^-1 at surface soil with a far below national land use of sludge of metal content prescribed limits.

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