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宁南山区两种灌木林土壤矿化过程中PLFA指纹季节变化特征 总被引:2,自引:0,他引:2
研究土壤矿化过程中土壤微生物群落结构的变化特征,对深入理解土壤中物质转化和养分迁移机理、提高土壤质量具有重要意义.因此,本文以宁南山区典型的两种人工灌木林-柠条和山桃林地土壤为研究对象,采用PVC顶盖埋管法进行1年的原位矿化实验,每隔2个月采样测定土壤基本理化性质和磷脂脂肪酸(Phospholipid fatty acid,PLFA)含量,探讨土壤在矿化过程中微生物群落结构的变化特征.结果显示:土壤矿化过程中,柠条林地土壤有机碳、全氮、硝态氮、铵态氮和土壤含水率显著高于山桃林地(p0.05);两种灌木林地有机碳含量在矿化240 d和360 d时较低,显著小于其他矿化时期(p0.05),硝态氮、铵态氮含量均在矿化240 d时最低,全氮和土壤pH随时间变化不显著.柠条林土壤各菌群PLFA含量高于山桃林土壤;两种土壤各菌群PLFA随矿化时间大体呈现出夏季春、秋季冬季的趋势,且差异显著(p0.05);土壤细菌与真菌、革兰氏阳性(GP)和阴性菌(GN)的PLFA比值差异显著(p0.05),柠条林土壤细菌与真菌PLFA比值随矿化时间呈现出夏、秋季春、冬季的趋势,而山桃林土壤细菌与真菌PLFA比值在冬季最低,两种土壤革兰氏阳性和阴性菌PLFA比值在春季最大.PLFA主成分分析表明,柠条和山桃林土壤微生物群落结构不同,并且土壤微生物群落结构随矿化时间逐步发生变异,微生物结构的变化主要由以16∶0、16∶1ω9c、16∶1ω9t、17∶0、10Me18∶0和cy19∶0所代表的细菌及以18∶2ω9,12c所代表的真菌的变化引起.土壤微生物PLFA与土壤有机碳、硝态氮和土壤含水率显著相关,与土壤pH值不相关,说明土壤微生物PLFA与土壤理化性质联系紧密. 相似文献
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荧光原位杂交法检测反应器中聚磷菌实验条件优化及应用 总被引:3,自引:0,他引:3
文章简要介绍了荧光原位杂交(FISH)技术的基本原理和操作步骤。通过正交试验筛检荧光原位杂交(FISH)技术在检测反应器中聚磷菌时的最佳及适合的实验条件。结果显示,样品预处理较优的条件为:样品在固定前应先经过1×PBS清洗两次,37℃热固定3h,乙醇脱水3min;FISH技术检测反应器中聚磷菌的最佳实验条件为:杂交温度46℃,杂交时间2h,清洗缓冲液中NaCl浓度70 mmol/L。FISH技术检测反应器样品中聚磷菌与传统检测方法相比具有快捷、简便、淮确的优点,在研究环境微生物方面有较好的应用前景。 相似文献
366.
Wei Tan Shaohua Xie Wenpo Shan Zhihua Lian Lijuan Xie Annai Liu Fei Gao Lin Dong Hong He Fudong Liu 《Frontiers of Environmental Science & Engineering》2022,16(5):60
367.
Mechanism for the destruction of carbon tetrachloride and chloroform DNAPLs by modified Fenton's reagent 总被引:1,自引:0,他引:1
The destruction of a carbon tetrachloride DNAPL and a chloroform DNAPL was investigated in reactions containing 0.5 mL of DNAPL and a solution of modified Fenton's reagent (2M H2O2 and 5mM iron(III)-chelate). Carbon tetrachloride and chloroform masses were followed in the DNAPLs, the aqueous phases, and the off gasses. In addition, the rate of DNAPL destruction was compared to the rate of gas-purge dissolution. Carbon tetrachloride DNAPLs were rapidly destroyed by modified Fenton's reagent at 6.5 times the rate of gas purge dissolution, with 74% of the DNAPL destroyed within 24h. Use of reactions in which a single reactive oxygen species (hydroxyl radical, hydroperoxide anion, or superoxide radical anion) was generated showed that superoxide is the reactive species in modified Fenton's reagent responsible for carbon tetrachloride DNAPL destruction. Chloroform DNAPLs were also destroyed by modified Fenton's reagent, but at a rate slower than the rate of gas purge dissolution. Reactions generating a single reactive oxygen species demonstrated that chloroform destruction was the result of both superoxide and hydroxyl radical activity. Such a mechanism of chloroform DNAPL destruction is in agreement with the slow but relatively equal reactivity of chloroform with both superoxide and hydroxyl radical. The results of this research demonstrate that modified Fenton's reagent can rapidly and effectively destroy DNAPLs of contaminants characterized by minimal reactivity with hydroxyl radical, and should receive more consideration as a DNAPL cleanup technology. 相似文献
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浅层地下水PCE/TCE污染原位曝气修复模拟研究 总被引:1,自引:2,他引:1
通过TMVOC软件模拟了PCE/TCE在渗流区"自然"环境条件下的污染物泄露、重新分布和原位曝气修复过程中的污染物运移行为,确定了最佳曝气流量和曝气时间。结果表明:PCE/TCE污染物在泄露和重新分布过程中在重力作用和毛细作用下污染范围不断扩大,污染羽在垂直方向到达隔水层,水平方向达到23.3m,顺水流方向的污染范围明显大于逆水流方向。曝气修复初期污染范围会有所扩大,但是污染物浓度和总量会减少,曝气影响范围并不是随着曝气流量的增加而线性增大,超过最佳曝气流量值后,增大曝气流量对影响范围的改变效果不大。论文研究条件下最佳曝气速率为6m3/h,影响半径达18m,需要45d完成修复,实际工程中应根据区域面积及地下水埋深确定曝气井数量。 相似文献
370.
Ming Chen Lena Q MaSatya P Singh Rocky X CaoRicardo Melamed 《Advances in Environmental Research》2003,8(1):93-102
A long-term field-scale demonstration project on the feasibility of using P to immobilize Pb in a Pb-contaminated urban soil was conducted. Phosphate was applied at an average rate of 3040 mg P/kg soil based on a P/Pb molar ration of 4.0, with four treatments: T0, no P application; T1, H3PO4 only; T2, 1/2 H3PO4+1/2 CaH2PO4; and T3, 1/2 H3PO4+1/2 phosphate rock. Soil samples were collected and analyzed 220 days after the P applications. For all P treatments, toxicity characteristic leaching procedure (TCLP) extractable Pb levels in surface soils (0-10 cm) were reduced to below 5.0 mg Pb/l, with T2 also effective in reducing the TCLP Pb level in subsurface soils (10-30 cm, <4.63 mg/l). Sequential extraction analysis indicates that P was effective in transforming soil Pb from non-residual fractions to a residual fraction. Such a transformation was mainly through dissolution of Pb associated with carbonate fraction and precipitation of pyromorphite-like minerals, which were confirmed using X-ray diffraction (XRD). Among these three treatments, T3 was the most effective in reducing Pb mobility and minimizing P and Pb leaching in the soil. Our research clearly demonstrates that P amendments were effective in immobilizing Pb in contaminated soil. 相似文献