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961.
国内首次运用FastPrep○R 核酸快速提取系统提取了重金属复合污染农田土壤的DNA ,并对其进行了聚合酶链反应—变性梯度凝胶电泳 (PCR DGGE)分析。结果表明 ,FastPrep○R核酸提取仪与相应的FastD NASPINKitforSoil试剂盒联用时 ,能有效地分离到纯度较高的重金属污染农田土壤的DNA。PCR DGGE电泳图谱表明 ,PCR产物经DGGE检测后得到的电泳条带清晰且分离效果好 ,可以明显反映出重金属复合污染导致了农田土壤微生物在基因上的损伤 ,影响到农田土壤生态系统的细菌丰富度 ,改变了土壤环境的优势菌群 ,从而使农田土壤微生物群落结构多样性发生变化。可见 ,FastPrep○R核酸提取系统同样适用于重金属污染农田土壤环境中微生物基因组DNA的快速分离和纯化 ,得到的DNA可直接用于PCR DGGE分析。 相似文献
962.
不同水分状况及施磷量对水稻土中速效磷含量的影响 总被引:13,自引:1,他引:13
通过室内培养试验研究了不同水分(淹水和60%田间持水量)及施P量对水稻土速效P及水层含P量的影响。结果表明,无论水分状况如何,土壤速效P含量随施P量的增加而呈明显增加趋势。土壤速效P出现富集的转折点因供试土壤而异,第三纪红壤性水稻土大致为P2O560~120mg/kg,而第四纪红壤性水稻土和黄泥土为P2O5120~180mg/kg。P肥施入土壤后,水溶性P主要存在于土壤溶液中,而分布于水层中的P相对较少。但在过量施P(P2O5>180mg/kg)时,施肥后短期内(0~30天),水层中P浓度较高(0.05~0.3mg/kg),如水分管理不当,则会造成P的损失。 相似文献
963.
通过对南京市公路绿地系统(城市干线、绕城公路和城郊公路)土壤重金属的调查和分析,并与相对清洁点植物园植被土壤进行比较,研究了公路绿地土壤重金属分布的特点:公路绿地土壤重金属元素含量一般高于“清洁区”,其中土壤Mo、Zn、As、Cd、Cr、Cu、Fe、Mn的含量以绕城公路最高,土壤Pb的含量以城市干线最高,土壤Al的含量以城郊公路最高。城市干线、绕城公路、城郊公路和相对清洁点的土壤重金属多样性指数分别为0 .2 6 1、0 .2 93、0 2 38、0 2 36 ,仍以绕城公路最高,城市干线次之,城郊公路最低,公路土壤重金属多样性指数均高于“相对清洁点”。应用主成分分析方法对土壤样本进行了排序和聚类分析,结果表明:样本点表现了较好的以取样路线聚类的特点,各取样点土壤重金属含量存在明显的演变分异。土壤重金属演变的趋势可解释为:绕城公路是高Zn、Mo、Cd、As、Cr、Fe、Mg、Cu、Mn、Pb区,城市干线是高Pb区,城郊公路是高Al和Fe区,相对清洁点是低重金属区 相似文献
964.
965.
北京百花山区自然土壤与耕作土壤的肥力比较以及土壤管理措施 总被引:2,自引:0,他引:2
通过对北京百花山地区山地自然土壤和耕作土壤有机质含量、全氮、全磷、速效磷、速效钾及微量元素有效含量的测定分析,得到了该地区山地自然土壤和耕作土壤的肥力特征。该地区山地自然土壤的有机质、全氮、全磷的含量较高,速效钾的水平中等,而速效磷的水平很低,微量元素中铜的含量较高,锰的含量较低,而有效锌的含量极低。自然土壤开垦为耕地后,土壤有机质含量明显降低,全氮的含量变化不明显;由于施肥作用,土壤全磷和速效磷的水平上升,个别耕地速效磷的水平极高,有过量使用磷肥的现象。对该地区山地土壤的开发利用,应坚持生态保护,防止水土流失,适当使用磷肥,注意使用微肥尤其是锌肥,因地制宜,根据不同地形、不同的土壤类型、母质的差异制定合理的利用方案。 相似文献
966.
967.
968.
Phosphorus losses by surface runoff from agricultural lands have been of public concern due to increasing P contamination to surface waters. Five representative commercial citrus groves (C1-C5) located in South Florida were studied to evaluate the relationships between P fractions in soils, surface runoff P, and soil phosphatase activity. A modified Hedley P sequential fractionation procedure was employed to fractionate soil P. Soil P consisted of mainly organically- and Ca/Mg-bound P fractions. The organically-bound P (biological P, sum of organic P in the water, NaHCO3 and NaOH extracts) was dominant in the acidic sandy soils from the C2 and C3 sites (18% and 24% of total soil P), whereas the Ca/Mg-bound P (HCl-extractable P) accounted for 45-60% of soil total P in the neutral and alkaline soils (C1, C4 and C5 soils). Plant-available P (sum of water and NaHCO3 extractable P fractions) ranged from 27 to 61 mg P kg−1 and decreased in the order of C3>C4>C1>C2>C5. The mean total P concentrations (TP) in surface runoff water samples ranged from 0.51 to 2.64 mg L−1. Total P, total dissolved P (TDP), and PO43−-P in surface runoff were significantly correlated with soil biological P and plant-available P forms (p<0.01), suggesting that surface runoff P was directly derived from soil available P pools, including H2O- and NaHCO3- extractable inorganic P, water-soluble organic P, and NaHCO3- and NaOH-extractable organic P fractions, which are readily mineralized by soil microorganisms and/or enzyme mediated processes. Soil neutral (55-190 mg phenol kg−1 3 h−1) and natural (measured at soil pH) phosphatase activities (77-295 mg phenol kg−1 3 h−1) were related to TP, TDP, and PO43−-P in surface runoff, and plant-available P and biological P forms in soils. These results indicate that there is a potential relationship between soil P availability and phosphatase activities, relating to P loss by surface runoff. Therefore, the neutral and natural phosphatase activities, especially the natural phosphatase activity, may serve as an index of surface runoff P loss potential and soil P availability. 相似文献
969.
970.
We evaluated the effect of elemental S (S0) under three moisture (40, 60, 120% water-filled pore space; WFPS) and three temperature regimes (12, 24, 36°C) on changes in pH and available P (0.5 N NaHCO3-extractable P) concentrations in acidic (pH 4.9), neutral (pH 7.1) and alkaline (pH 10.2) soils. Repacked soil cores were incubated for 0, 14, 28 and 42 days. Application of S0 did not alter the trends of pH in acidic and neutral soils at all moisture regimes but promoted a decrease in the pH of alkaline soil under aerobic conditions (40%, 60% WFPS). Moisture and temperature had profound effects on the available P concentrations in all three soils, accumulation of available P being greatest under flooded conditions (120% WFPS) at 36°C. Application of S0 in acidic, neutral and alkaline soils resulted in the net accumulation of 16.5, 14.5 and 13 g P g–1 soil after 42 days at 60% WFPS, but had no effect under flooded conditions. The greatest available P accumulations in the respective soils were 19, 19.5 and 20 g P g–1 soil (equivalent to 38, 41, 45 kg P ha–1) with the combined effects of 36°C, 60% WFPS and applied S0. The results of our study revealed that oxidation of S0 lowered the pH of alkaline soil (r=–0.88, P<0.01), which in turn enhanced available P concentrations. Also, considering the significant relationship between the release of sulphate and accumulation of P, even in acidic soil (r=0.92, P<0.01) and neutral soil (r=0.85, P<0.01) where the decrease in pH was smaller, it is possible that the stimulatory effect of sulphate on the availability of P was due to its concurrent desorption from the colloidal surface, release from fixation sites and/or mineralization of organic P. Thus, in the humid tropics and irrigated subtropics where high moisture and temperature regimes are prevalent, the application of S0 could be beneficial not only in alleviating S deficiency in soils but also for enhancing the availability of P in arable soils, irrespective of their initial pH. 相似文献