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维系微囊藻群体结构的胶鞘是微囊藻水华维持优势的重要原因之一.为了探讨微囊藻水华的衰亡机理,在太湖梅梁湾水华衰亡过程中(10月至次年1月),对微囊藻群体大小的组成做了统计,同时对单位藻细胞的胶鞘多糖产量变化进行了检测,并对微囊藻群体胶鞘的变化进行了能谱扫描电镜观察和元素组成分析.结果表明,随着水华的衰亡,100~180μm的微囊藻小群体的比例表现出增多的趋势,而大于180μm的大群体逐渐减少,单位藻细胞的多糖含量呈现下降的趋势.扫描电镜结果显示了微囊藻群体的胶鞘从完整到逐渐裂解的变化过程,群体表面的能谱化学元素分析显示,钠和磷元素的百分含量呈下降的趋势,铝和硫元素的百分含量趋于稳定,而钙和硅元素的百分含量呈上升的趋势.以上结果说明了微囊藻群体中单位细胞的多糖产量减少,群体胶鞘裂解,元素组成发生变化,伴随着微囊藻群体的解聚,出现水华的衰亡. 相似文献
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用刚收割的水稻(Oryza sativa L.)秸秆浸提液代替水配制培养基培养铜绿微囊藻(Microcystic aeruginosa),追踪测定微囊藻的生物量、叶绿素a含量、光合速率、呼吸速率、膜透性、超氧物歧化酶(SOD)活性、光合膜自发荧光强度等相关生理生化指标的变化,研究水稻秸秆浸液对铜绿微囊藻的抑制作用.结果表明,质量比≥1/100(水稻秸秆/水)的水稻秸秆浸提液对微囊藻的生长有明显的抑制作用,表现如下:藻细胞生物量在实验过程中逐日降低,藻细胞叶绿素a含量和光合速率急剧下降,呼吸速率和超氧物歧化酶(SOD)活性呈先升高后下降的趋势,膜透性迅速升高,细胞光合膜自发荧光强度显著衰减.用不同的有机溶剂对该浸提液进行萃取,浓缩后用滤纸片法在固体培养基上做抑藻实验,乙醚和乙酸乙酯萃取液能明显看到抑藻圈,证实其中含有抑制物质. 相似文献
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低氧化还原电位对铜绿微囊藻(Microcystis aeruginosa)生长的抑制及恢复的影响 总被引：1，自引：0，他引：1
在实验室光照黑暗交替培养下,用半胱氨酸下调黑暗起始时的氧化还原电位(ORP),研究低电位对铜绿微囊藻(Microcystis aeruginosa FACHB 469)生长的影响,并探索低电位胁迫消除后铜绿微囊藻生长的恢复潜力.结果表明,在-50～-100 mV范围内水体ORP越低,其对铜绿微囊藻生长的抑制作用越强.低ORP可抑制铜绿微囊藻对磷的吸收,且这种抑制程度与电位变化无关.-50～-75 mV的电位对铜绿微囊藻SOD酶活性有促进作用,而-90～-100 mV电位明显抑制SOD酶活.当低ORP胁迫消除后,铜绿微囊藻能够恢复至最初的生长状态,同时伴随含磷量的提高和SOD酶活的恢复,-50～-75 mV电位胁迫对藻消除胁迫后的生长更有促进作用.因此,低ORP对铜绿微囊藻的生长会产生不利影响,但是该影响是可逆的. 相似文献
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铜绿微囊藻生长对培养液pH值和氮转化的影响 总被引：4，自引：0，他引：4
在不同初始pH值条件下培养蓝藻水华优势种铜绿微囊藻(Microcystis aeruginosa),研究其生长过程对培养液的pH值和氮转化的影响,结果表明,处于延迟期和对数生长期的铜绿微囊藻使培养液的pH值上升,pH从初始的7.2、8.0和8.8分别上升到最大值10.02、10.34和10.94;稳定期和衰亡期的微囊藻使培养液pH值降低,初始pH值为8.8时,最终pH降至8.66,在微囊藻生长过程中,培养液中NO3-含量逐渐降低,NO3-含量先升高再降低,分别在60d和67d后降至零.试验结束时,不同pH值培养液中总氮含量比起始时分别下降了25.97%、27.52%和28.16%,说明化合态无机氮可以经过反硝化作用生成氮气而溢出培养液,因此,较大密度水华水体中存在反硝化的脱氮过程. 相似文献
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黑藻(Hydrilla verticillata)对铜绿微囊藻(Microcystis aeruginosa)抑制作用 总被引：17，自引：0，他引：17
采用黑藻(Hydrilla verticillata)和铜绿微囊藻(Microcystis aeruginosa)共同培养的实验方法，追踪测定微囊藻的生长量、光合速率等相关生理生化指标以及观察藻细胞超微结构变化，研究黑藻对铜绿微囊藻的抑制作用及其机制．结果表明，黑藻对铜绿微囊藻的生长有明显的抑制作用，表现为藻细胞生长量显著降低，细胞超微结构进行性损伤直至细胞解体，藻体叶绿素a含量和光合速率急剧下降，呼吸速率、超氧物歧化酶(SOD)活性均呈现先升高后下降的趋势，膜脂过氧化产物丙二醛(MDA)的积累量与膜的损伤程度相一致．在黑藻养殖水中初步分离得到黑藻分泌的抑藻物质． 相似文献
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河蟹养殖池塘微囊藻水华毒性及其光合作用活性特征 总被引：1，自引：0，他引：1
苏州市吴中区一河蟹养殖池塘在2013年7月和8月发生了严重的微囊藻水华.采用单一和双重PCR扩增微囊藻毒素合成酶基因,用以检测微囊藻水华是否产毒,结果显示为阳性.同时,采用高效液相色谱测定微囊藻水华的毒性大小.结果表明:7月和8月微囊藻水华的胞内微囊藻毒素浓度分别为1.49和0.88μg/L,胞外微囊藻毒素的浓度分别为0.75和1.09μg/L.另外,采用浮游植物荧光仪Phyto-PAM测定河蟹养殖水体形成水华的微囊藻的光合作用活性.结果显示:7月和8月水华微囊藻的最大光量子产量Fv/Fm分别为0.48和0.44,实际光量子产量ΦPSII分别为0.38和0.32,表明形成水华的微囊藻有较高的生长潜力.非光化学荧光淬灭值NPQ分别为0.28和0.36.从快速光响应曲线RLC的特征参数来看,7月水华微囊藻的光合作用活性和光能利用效率高于8月.本研究结果表明,河蟹养殖池塘水体受到微囊藻水华和微囊藻毒素的污染,进而可能对河蟹食品安全构成潜在威胁. 相似文献
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光照强度对水华微囊藻(Microcystis flos-aquae)群体大小增长的影响 总被引：2，自引：1，他引：1
大量微囊藻群体的形成和聚集是微囊藻水华形成的重要条件.光照强度是影响微囊藻生长的重要因素之一.为了了解光照强度对水华微囊藻(Microcystis flos-aquae)群体大小增长的影响,以太湖微囊藻水华优势种之一的水华微囊藻作为研究对象,开展了不同光照强度对水华微囊藻群体大小增长的影响研究.共设置5个不同光强处理组,依次为G1:2000 lx;G2:4000 lx;G3:8000 lx;G4:16000 lx;G5:变化光照强度(模拟野外光强).实验期间,G1~G5组大于100细胞群体的平均大小分别为255、480、630、763和662 cells/群体.胞外多糖含量分析显示水华微囊藻形成的群体越大,胞外多糖含量越高.结果表明,低光照强度不利于太湖水华微囊藻群体大小的增长,而变化光照强度和高光照强度有利于水华微囊藻群体大小的增长.研究结果解释了太湖夏季野外变化光照强度和高光照强度有利于微囊藻水华形成的原因. 相似文献
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关注微囊藻群体在超声处理下光合活性变化及超声解除后的浮力恢复情况,可以为超声波控藻技术提供理论依据和数据支撑,具有重要的实践意义.本研究采用处理后水柱中叶绿素a浓度的垂向分布比例和叶绿素荧光变化情况分析微囊藻群体在超声波处理下的光合活性变化和沉降过程.结果表明,适量的超声处理(35 kHz、0.0353 W/cm~3)能在避免破裂藻细胞的同时,显著抑制其光合活性;60 s的处理造成了45.5%的光合活性被抑制.然而,在适宜生长条件下,所有实验组藻细胞中受抑制的光合活性均在24 h内恢复至对照组的80%左右.此外,在上述超声条件下,5 s的超声处理能使水柱中叶绿素a浓度在短时间内(0.5 h)的去除率达79.5%.然而,当处理时间小于30 s时,大于90%的沉降藻细胞可在超声解除后的72 h内恢复浮力上浮;而当处理时间延长至60 s以后,藻细胞基本丧失了上浮能力.通过分析发现,超声处理后微囊藻群体的粒径分布对藻细胞沉降及上浮过程起决定性作用,并且还发现微囊藻群体在超声处理时首先表现为藻细胞失去浮力下沉和光合系统受损,进而发生大群体振散. 相似文献
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《中国科学:地球科学(英文版)》2014,(3)
正SCIENCE CHINA Earth Sciences,an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press and Springer,is committed to publishing high-quality,original results in both basic and applied research. 相似文献
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《国际泥沙研究》2014,(4)
正Director:Shangfu Kuang,China Vice-directors:Chunhong Hu,China Duihu Ning,China Guangquan Liu,China The International Research and Training Center on Erosion and Sedimentation(IRTCES)was jointly set up by the Government of China and UNESCO on July 21,1984.It aims at the promotion of international exchange of knowledge and cooperation in the studies of erosion and 相似文献
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Richard D. Hey 《地球表面变化过程与地形》1979,4(1):59-72
Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape. 相似文献
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Based on relocating the Jiujiang-Ruichang earthquake sequence which occurred on November 26, 2005 in Jiangxi Province with the double-difference （DD） algorithm and master event technique, the paper discusses the focal mechanism of the main shock （MsS.7） and the probable seismo-tectonics. The precise relocation results indicate that the average horizontal error is 0.31kin in a EW direction and 0.40kin in a NS direction, and the average depth error is 0.48kin. The focal depths vary from 8kin to 14kin, with the predominant distribution at 10kin - 12kin. The epicenter of the main shock is relocated to be 29.69^oN, 115.74^oE and the focal depth is about 10.Skin. Combining the predominant distribution of the earthquake sequence, the focal mechanism of the main shock and the tectonic conditions of N-E- and NW-strike faults growth in the seismic region, we infer that the main shock of the earthquake sequence was caused by a NW striking buried fault in the Rnichang basin. The nature of seismic faults needs to be further explored. 相似文献
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《水文科学杂志》2013,58(6)
Abstract The western reservoirs represent the principal groundwater system in Morocco. Demographic, industrial and agricultural developments during the last decade have markedly altered groundwater quality. The Mamora coastal aquifer system is among the Atlantic systems which are most heavily threatened by pollution. Agricultural and industrial activities, and rapid urban growth contribute to the pollution of the groundwater. Contamination transport is facilitated by a high permeability of the aquifer formations. In order to assess the actual groundwater quality of the Mamora aquifer and to understand the influence of the factors generating the pollution, an extensive multidisciplinary research programme is in progress, with hydrochemistry and microbiology playing essential roles. The present paper concerns the spatial distribution of physico-chemical parameters in the groundwater, subjected to domestic, industrial and agricultural pollution. Fifty-seven samples were analysed for several parameters (Ca2+, Mg2+, Na+, K+, Cl?, SO4 2?, HCO3 ?, NO3 ?, pH, electrical conductivity and temperature). The microbiological analysis of 143 samples reveals the presence of four kinds of indicator bacteria in the groundwater resources: faecal Streptococci, faecal coliform, Escherichia coli and Clostridium. The physico-chemical results and bacteriological monitoring show that the nitrate and bacteria concentrations exceed the maximum admissible levels, notably around pumping stations in the sectors of Sidi Taibi, Sidi Ahmed Taleb and Aïn Sbaâ. Contamination is generated by uncontrolled anthropogenic activities and accentuated by the high intrinsic vulnerability of the aquifer system. Several parameters appeared to exceed admissibility standards. Measures are recommended to prevent groundwater pollution in the region. 相似文献
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K.-G. Malle 《洁净——土壤、空气、水》1992,20(4):196-204
Zinc in the Environment. In 1990 the world production of zinc ammounted to 7 Mio. metric tons. The main areas of application were: galvanization, alloys like brass and zinc metal. The content in the earth crust varies between 10–300 ppm zinc with a mean of 70 ppm. Uncontaminated surface waters contain less than 10 mg/m3 zinc. Apart from civilization air contains 1–10 ng zinc per m3. These background concentrations are exceeded by orders of magnitude in zinc deposit areas and where anthropogenic influences predominate. Accumulation can occur in sediments and sewage sludge. Molluscs and Algae also accumulate zinc. Zinc is essential for live. With normal food the zinc supply of man is just sufficient. Bioaccumulation of zinc towards man or chronic oversupply of man is not known. Zinc has no teratogenic or mutagenic effects, a suspicion on a carcinogenic effect proved wrong. In stockbreeding and plant cultivation a minimum supply of zinc is necessary. Plants are relatively less sensitive against higher soil contents of zinc. Considering the toxicological and ecotoxicological effects of zinc in the environment, the critical organismens are marine invertebratae like tubifex, daphnia, gammarus and algae. But normally only a minor part of the total zinc contest is biologically available, depending on salt content and pH of the waters. 相似文献