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41.
Relationship between the δ^13C of tree ring cellulose from Pinus Koraiensis and climate parameters was investigated.A significantly negative correlation between δ^13C and mean low-cloud amount from May to July was discovered,which contributes to reconstructing the mean low-cloud amount form May to July at Antu in recent 200years.Periodicals of quasi-8-year,quasi-4-year and quasi-2-year were detected both in δ^13 C series and in the reconstructed low cloud amount series with 95% confidence level.Quasi-8-year period may reflect the integrated influence of solar activity,monsoon activity and local regional factors.Quasi-4-year and quasi-2-year periods indicate the influences of ENSO and Qussi Biennial Oscillation(QBO)of East Asian monsoon,respectively. 相似文献
42.
三正辛胺纤维棉对金的吸附性能及其在测定金中的应用 总被引：2，自引：0，他引：2
研制了三正辛胺（ＴＯＡ）纤维棉,考察了ＴＯＡ纤维棉对Ａｕ（Ⅲ）的吸附性能,选择了吸附和解吸的最佳条件。在φ＝１０％的王水中,ＴＯＡ纤维棉可定量吸附Ａｕ（Ⅲ）,使其与多种共存离子分离。吸附的Ａｕ（Ⅲ）用１０ｇ／Ｌ的Ｎａ２ＳＯ３溶液解脱。在给定条件下,对５～２００μｇＡｕ（Ⅲ）进行分离富集,其回收率在９８０％～１０１０％。方法已用于氧化金铅矿、铅锌矿、银金矿中金的分离富集和测定,所得结果与其它方法相符,其ＲＳＤ（ｎ＝５）为１６％～３９％。 相似文献
43.
Because of the aridity of the Namib Sand Sea, it has long been assumed that decomposition of buried plant material was largely independent of rainfall. Losses were attributed to consumption by detritivores that forage year-round. Moisture-limited micro-organisms were reported to occur in low densities in Namib sands, supporting the assumption that rainfall was insignificant in regulating decomposition. Observations of abundant macrofungal fruiting from buried plant material and herbivore dung, following a 12 mm rain, suggested the importance of rain-induced decomposition had been underestimated. We used cellulose substrates to compare material loss during dry periods and following differing amounts of rain. Strips of cotton cloth and filter paper, buried at 10 cm depths at five disjunct locations, were sequentially removed over 10 months. A period of at least 170 days elapsed before rains, ranging from 4–46 mm, fell at all locations. Material loss during the dry period averaged 8·2% (range 0–16·7%), and was attributed to macrodetritivore consumption. In marked contrast, an average of 84·1% of the material (range 64·7–97·2%) was lost following rains greater than 9 mm. Wet substrates were heavily colonized by fungi, and termites and tenebrionid beetle larvae were observed feeding on fungus-colonized substrates. Stepwise regression analysis revealed that rainfall, rather than duration of burial, was the primary factor determining substrate loss in the Namib Sand Sea. Although rain events are infrequent and ensuing periods of moist soil are brief, substrate loss following rains is highly significant relative to that occurring in the absence of rain. In contrast to more mesic deserts, rainfall is an important trigger of decomposition in the Namib Sand Sea where soils are too dry to support significant decomposition, except when episodically moistened by rain. 相似文献
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高效纤维素降解菌系的构建 总被引：1，自引：0，他引：1
筛选出能产生不同纤维素酶的10株纤维素降解菌, 系统地分析了各菌株的EG、CBH和BG酶等3类纤维素酶活.经各菌株优化组合、混合培养, 构建了一组由5株细菌(LCB03、LCB12、LCB52、LCD12和LCD51)组成、能协同作用的复合微生物菌系.经生理生化和分子水平鉴定, 这5株细菌分别为Pseudomonas citronellolis(香茅醇假单胞菌)、Stenotrophomonas malto-philia(嗜麦芽寡食单胞菌)、Pseudomonas aeruginosa(铜绿假单胞菌)、Pseudomonas aeruginosa(铜绿假单胞菌)和Flavobacterium mizutaii(水氏黄杆菌).复合菌系的各菌株可产生不同类型的纤维素酶, 且各类酶可以协同作用有效分解天然纤维素, 在纤维素类污染的治理与资源化利用中具有很好的应用前景. 相似文献
45.
科尔沁沙质草地纤维素分解菌的筛选、鉴定及其分解能力 总被引：1，自引：0，他引：1
从科尔沁沙质草地土壤中,通过分离、纯化、初筛和复筛得到2株分解纤维素(CMC)能力较强的真菌(NM1-1和NM1-2),采用形态学和rDNA-ITS分子生物学相结合的方法鉴定分别为伪弯头曲霉(Asperigillus pseudodeflectus)和尖孢镰刀菌(Fusarium oxysporum)。NM1-1和NM1-2对布条的分解效果较好,30 d的分解率分别达到15.69%和16.91%;凋落物分解试验表明,加NM1-1和NM1-2的草地凋落物分解率在30 d内分别达53.61%和45.72%,分别比对照高7.70和6.42倍。NM1-1和NM1-2的CMC酶活性显著高于其生存的土壤环境。科尔沁沙质草地土壤高效纤维素分解菌的分离和筛选不仅补充了沙质草地土壤功能微生物库,同时对沙地凋落物分解和土壤有效养分输入起到促进作用。 相似文献
46.
Oxygen isotope ratios of organic matter in arctic lakes as a paleoclimate proxy: field and laboratory investigations 总被引：6，自引：5，他引：1
Paleoclimate research based on the stable isotopic composition of lake sediments is often hampered by the lack of preservation of suitable material for isotopic analysis. We examined organic material as a proxy for past water isotopic composition in a series of experiments. First, we cultured aquatic moss under constant illumination, temperature, and water 18O, and show that new cellulose records source water 18O precisely (r2 = 0.9997). Second, we analyzed paired lakewater and vegetation samples collected from sites spanning strong climatic gradients. In field conditions, the relationship between organic 18O and water 18O is more variable, though it is still controlled by environmental water isotopic composition. However, terrestrial mosses in the arctic are often significantly enriched in 18O relative to aquatic mosses in nearby lakes due to their use of different water sources. Third, we measured 18O of cellulose extracted from disseminated sedimentary organic material. In the majority of the middle- to high-arctic lakes in this study, the 18O of disseminated sediment cellulose is greatly enriched relative to the expected values based on lakewater 18O, suggesting a significant component of terrestrial cellulose. This interpretation is supported by radiocarbon dates from a Holocene sediment core in which 14C ages of sediment cellulose are 700-5000 yrs older than the enclosing sediments. We conclude that aquatic cellulose can be used as a reliable tracer of lakewater isotope ratios, but terrestrial cellulose often dominates the sedimentary cellulose pool in places such as Baffin Island where sedimentation rates are low enough to allow the degradation of aquatic cellulose. Care must be taken when interpreting sediment cellulose 18O records where diagenesis has played a role, because terrestrial cellulose is more resistant to degradation, and therefore can predominate in environments with low organic carbon burial. 相似文献
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48.
采用稀释涂板法研究了南麂岛海域沉积物中海洋放线菌的分离技术,分析了真空干燥处理、热处理、海水浓度、培养基种类等因素对分离效果的影响;首次将羧甲基纤维素钠(CMC)溶液应用于海洋沉积物样品的预处理,探讨了不同浓度的CMC对海洋沉积物样品中放线菌分离结果的影响。结果表明:海洋沉积物经干燥处理、50℃热处理20 min均能有效地减少细菌数量,利于海洋沉积物中放线菌的分离;60%的海水配制的培养基对海洋放线菌的分离效果优于纯海水所配培养基,并且培养基中添加海泥浸出液能有效地增加海洋放线菌的出菌率;以质量浓度为2 g/L的CMC为分散剂时,不仅能良好地分散沉积物样品中的放线菌孢子,而且能明显地增加海洋放线菌的检出量及稀有放线菌的数量。 相似文献