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101.
102.
DONG‐RU ZHANG MING‐YONG CHEN ROBERT W. MURPHY JING CHE JUN‐FENG PANG JIAN‐SHENG HU JING LUO SHAN‐JIN WU HUI YE YA‐PING ZHANG 《Molecular ecology》2010,19(16):3406-3420
Historical drainage patterns adjacent to the Qinghai‐Tibetan Plateau differed markedly from those of today. We examined the relationship between drainage history and geographic patterns of genetic variation in the Yunnan spiny frog, Nanorana yunnanensis, using approximately 981 base pairs of mitochondrial DNA partial sequences from protein‐coding genes ND1 and ND2, and intervening areas including complete tRNAIle, tRNAGln and tRNAMet. Two null hypotheses were tested: (i) that genetic patterns do not correspond to the development of drainage systems and (ii) that populations had been stable and not experienced population expansion, bottlenecking and selection. Genealogical analyses identified three, major, well‐supported maternal lineages, each of which had two sublineages. These divergent lineages were completely concordant with six geographical regions. Genetic structure and divergence were strongly congruent with historical rather than contemporary drainage patterns. Most lineages and sublineages were formed via population fragmentation during the rearrangement of paleodrainage basins in the Early Pliocene and Early Pleistocene. Sympatric lineages occurred only in localities at the boundaries of major drainages, likely reflecting secondary contact of previously allopatric populations. Extensive population expansion probably occurred early in the Middle Pleistocene accompanying dramatic climatic oscillations. 相似文献
103.
广东横石水河大型底栖动物群落与环境因子的关系 总被引:1,自引:0,他引:1
应用典范对应分析(CCA)对横石水河流域14个样点中的大型底栖动物与环境因子的关系进行了研究。结果表明,枯水期和丰水期的物种与环境因子的相关性均在90%以上,说明大型底栖动物在横石水河的分布很大程度上受到环境因子的影响。化学需氧量(COD)和pH值是影响枯水期大型底栖动物分布的两个主要因子,浊度和重金属Cu、Pb浓度对大型底栖动物分布也有一定程度的影响。在丰水期,重金属Cu、Pb浓度和pH值是影响大型底栖动物分布的关键因子。从种类水平看,耐污种类如蠓类、摇蚊和大蚊的丰富度与COD和重金属浓度的环境轴呈正相关,而敏感种类如腹足纲、毛翅目以及蜉蝣目昆虫与COD和重金属浓度的环境轴呈负相关。 相似文献
104.
The North American catfish, the black bullhead Ameiurus melas, is recorded for the first time in Poland. The origin of these fish is not clear, but their presence may be associated with unregulated introductions by anglers. 相似文献
105.
养殖排放农药和抗生素在红树林区中残留的初步研究 总被引:2,自引:0,他引:2
广西北海大冠沙红树林区是养殖废水的排放地,该文报道2008年10月农药和抗生素在该林区红树林滩、沙滩和潮沟三类生境的残留水、沉积物和底栖动物中的分布与含量。通过对103种农药和22种抗生素检测,发现该林区有16种农药,4种抗生素,其中甲氰菊酯、仲丁威和醚菌酯是主要的污染农药。在残留水中检出12种农药,它们在红树林滩、沙滩和潮沟中的总浓度分别是42.70、29.63和27.41ng/L。在沉积物中检出10种农药,它们在红树林滩、沙滩和潮沟中的总浓度分别是7.90、6.70和7.29μg/kg.DW。在底栖动物体内检出4种农药和3种抗生素。分析表明,红树林滩(残留水和沉积物)比底栖动物更易受到养殖废水的污染,底栖动物对抗生素的富集能力似乎高于对农药的富集能力,生境间污染相似度高于样品间的污染相似度。 相似文献
106.
应用锥颅置管引流手术治疗急性高血压脑出血 总被引:2,自引:1,他引:1
探讨应用锥颅置管引流术治疗急性高血压脑出血的临床治疗效果。方法:对62例应用锥颅置管引流术治疗的高血压脑出血病人进行了回顾性分析。对高血压脑出血的全组病例的发病年龄、性别、诱发病因、病史、常见发病部位、类型、手术方式以及临床效果进行了分析。结果:手术后2—6个月,按COS方法判定病人治疗效果。手术治疗结果:全组有痊愈者20例,中残者23例,重残者9例,植物生存者4例,死亡者6例(死亡率为10%)。结论:锥颅置管引流的手术方式,安全、医疗费用非常低廉,而且该手术后并发症和死亡率均降低。加之它简便,疗效确切,故值得临床广泛推广应用。 相似文献
107.
Several biotreatmemt techniques for sulfate conversion by the sulfate reducing bacteria (SRB) have been proposed in the past, however few of them have been practically applied to treat sulfate containing acid mine drainage (AMD). This research deals with development of an innovative polypropylene hollow fiber membrane bioreactor system for the treatment of acid mine water from the Berkeley Pit, Butte, MT, using hydrogen consuming SRB biofilms. The advantages of using the membrane bioreactor over the conventional tall liquid phase sparged gas bioreactor systems are: large microporous membrane surface to the liquid phase; formation of hydrogen sulfide outside the membrane, preventing the mixing with the pressurized hydrogen gas inside the membrane; no requirement of gas recycle compressor; membrane surface is suitable for immobilization of active SRB, resulting in the formation of biofilms, thus preventing washout problems associated with suspended culture reactors; and lower operating costs in membrane bioreactors, eliminating gas recompression and gas recycle costs. Information is provided on sulfate reduction rate studies and on biokinetic tests with suspended SRB in anaerobic digester sludge and sediment master culture reactors and with SRB biofilms in bench-scale SRB membrane bioreactors. Biokinetic parameters have been determined using biokinetic models for the master culture and membrane bioreactor systems. Data are presented on the effect of acid mine water sulfate loading at 25, 50, 75 and 100 ml/min in scale-up SRB membrane units, under varied temperatures (25, 35 and 40 °C) to determine and optimize sulfate conversions for an effective AMD biotreatment. Pilot-scale studies have generated data on the effect of flow rates of acid mine water (MGD) and varied inlet sulfate concentrations in the influents on the resultant outlet sulfate concentration in the effluents and on the number of SRB membrane modules needed for the desired sulfate conversion in those systems. The pilot-scale data indicate that the SRB membrane bioreactors systems can be applied toward field-scale biotreatment of AMD and for recovery of high purity metals and an agriculturally usable water. 相似文献
108.
A novel type of macroscopic microbial community consisting of large dendritic filaments (up to 1.5 m) in a pH 2.0 dam of the River Tinto (South-western Spain) is described. The combined use of 16S rRNA-gene surveys and fluorescent in situ hybridisation (FISH) suggested that gamma-proteobacteria and a relative large diversity of alpha-proteobacteria dominated these structures. beta-Proteobacteria, Actinobacteria and Firmicutes were also detected. Whereas acidophilic bacteria of the genera Acidithiobacillus, Leptospirillum and Acidiphilium, and archaea belonging to the Thermoplasmatales dominate mine acid drainage waters and streamers (riverbed filamentous biofilms), none of the lineages identified in this study affiliate to typical acid mine drainage acidophilic bacteria. Bacteria of the Tinto macrofilaments might be heterotrophic, and could be feeding on the organic matter entrapped in the filamentous structure. 相似文献
109.
Calcareous fens in Minnesota are spring-seepage peatlands with adistinctive flora of rare calciphilic species. Peat characteristics andgroundwater geochemistry were determined for six calcareous fens in theMinnesota River Basin to better understand the physical structure andchemical processes associated with stands of rare vegetation. Onset of peataccumulation in three of the fens ranged from about 4,700 to 11,000 14C yrs BP and probably resulted from acombination of climate change and local hydrogeologic conditions. Most peatcores had a carbonate-bearing surface zone with greater than 10%carbonates (average 27%, dry wt basis), an underlyingcarbonate-depleted zone with 10% or less carbonates (average4%), and a carbonate-bearing lower zone again with greater than10% carbonates (average 42%). This carbonate zonation washypothesized to result from the effect of water-table level on carbonateequilibria: carbonate precipitation occurs when the water table is above acritical level, and carbonate dissolution occurs when the water table islower. Other processes that changed the major ion concentrations inupwelling groundwater include dilution by rain water, sulfate reduction orsulfide oxidation, and ion adsorption or exchange. Geochemical modelingindicated that average shallow water in the calcareous fens during the studyperiod was groundwater mixed with about 6 to 13% rain water.Carbonate precipitation in the surface zone of calcareous fens could bedecreased by a number of human activities, especially those that lower thewater table. Such changes in shallow water geochemistry could alter thegrowing conditions that apparently sustain rare fen vegetation. 相似文献
110.
Fernández O. A. Murphy K. J. López cazorla A. Sabbatini M. R. Lazzari M. A. Domaniewski J. C. J. Irigoyen J. H. 《Hydrobiologia》1998,380(1-3):15-25
This study examines the relationships between fish, environmental variables and submerged macrophytes within the irrigation
system of the lower valley of the Río Colorado in southern Argentina. Using Canonical Correspondence Analysis (CCA), the strongest
environmental gradients detected were conductivity and carp ( Cyprinus carpi) biomass per unit area of channel cross-section.
These variables were positively associated with each other and also with water turbidity. Sites scoring high on these gradients
were mainly drainage channels; those scoring lowest were irrigation channels. The main fish species associated with high carp
biomass, high turbidity and high conductivity were carpa ( C. carpio), pejerrey ( Odontesthes bonariensis), madrecita ( Jenynsia
lineata lineata) and lisa ( Mugil liza). Dientudo ( Oligosarcus jenynsi) and mojarra ( Astianax eigenmanniorum) were more
strongly associated with clearer water, with low carp biomass. In all CCA analyses macrophytes were arranged in similar order
along the main conductivity-turbidity-carp biomass gradient. Lowest on this main environmental gradient, and scoring very
close to each other, were Potamogeton pectinatus and Chara contraria. Salinity-tolerant species such as Ruppia maritima, Zannichellia
palustris and Enteromorpha flexuosa tended to score highest, followed by the surface floating Azolla filiculoides and the
filamentous alga Cladophora surera. Within the constraints imposed by conductivity, turbidity was a key predictor of both
abundance and distribution of the two dominant plants of the irrigation scheme ( P. pectinatus and C. contraria). Turbidity
was strongly predicted by biomass of carp per unit channel cross sectional area, when fine sediment particle content was taken
into account. The positive association between carp biomass and water turbidity was both substantial and predictable, and
was in turn associated with reduction in submerged plant growth. The biomass of the most widespread nuisance-causing plant
species in the channels, Potamogeton pectinatus, could best be predicted ( R = 0.592, P < 0.05) using a multiple regression
model utilising four predictor variables: conductivity, nitrate, phosphate and carp biomass.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献