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771.
分层型水库水体好氧不产氧光合细菌时空演替特征 总被引:1,自引:1,他引:0
好氧不产氧光合细菌(aerobic anoxygenic photosynthesis bacteria,AAPB)以多样的群落结构及独特的代谢功能在水体物质循环中扮演着重要角色.基于实时荧光定量PCR及Illumina MiSeq高通量DNA测序技术研究金盆水库水体中AAPB丰度及群落结构时空演替特征,结合冗余分析揭示环境因子对其群落结构影响规律.结果表明,金盆水库水体AAPB丰度(以pufM基因计)变化范围为(6.70±0.43)×103~(2.69±0.15)×104 copies·mL-1,最大值出现于10月,且随水深增加而减小.样本主要归为19个属(除未分类菌属外),优势AAPB菌属包括慢生根瘤菌属(Bradyrhizobium sp.)和甲烷菌属(Methylobacterium sp.),两者隶属α-变形菌(α-Proteobacteria),其中慢生根瘤菌属(Bradyrhizobium sp.)占比于11月最高,高达60%以上(除10 m外),此外也发现了以低比例存在的红长命菌属(Rubrivivax sp.),隶属β-变形菌(β-Proteobacteria).AAPB不同属间存在较强的互作关系,如红杆菌属(Rhodobacter sp.)与小红卵菌属(Rhodovulum sp.)呈正相关,噬氢菌属(Hydrogenophaga sp.)与慢生根瘤菌属(Bradyrhizobium sp.)呈负相关等.AAPB种群结构组成及分布差异显著,主要受T、TN、NO3--N和光照强度影响,且由环境因素综合调控.如10月水深0、5和15 m水体AAPB种群结构受水温(T)、总氮(TN)和总磷(TP)显著影响,12月水深5 m水体AAPB种群结构受光照强度、pH、溶解氧(DO)和叶绿素a(Chla)显著影响等.研究结果对解析分层型水库水体AAPB丰度和多样性的时空变化特征具有指导意义,并为探索AAPB种群结构的水环境驱动因素提供理论依据. 相似文献
772.
泄漏是化工过程中很重要的风险事故,危险化学品的泄漏容易发生中毒或转化为火灾爆炸事故。将模糊综合评价模型应用于化工码头罐区的泄漏事故风险评价中,对重大危险源泄漏引起中毒的严重度进行排序,有助于确定安全管理工作的重心。 相似文献
773.
774.
The sedimentation of metals can preserve the historical record of contaminant input from local and regional sources and provide information on the historical changes in regional water and sediment quality. We report the 210Pb activities and the heavy metal (Cd, Cr, Cu, Mn, Pb and Zn) depth profiles from sediment cores retrieved in 2010. The mean sedimentation rates of 0.85-1.5 cm/yr are determined by 210Pb dating. The sediments in the tidal flat have recorded heavy metal deposition and thus allow the establishment of a connection between the temporal evolution of the heavy metal pollution and the historical changes in the economic development of Lianyungang. The enrichment factors (EF) are calculated to estimate the level of contamination stored in these sediments. The results show that in the studied sites, Cr and Cu display low EF values and are mainly from lithogenic origin. For the other studied trace metals, a great variability in the sedimentary record is observed. Significant anthropogenic enrichment over the last 50 years is revealed at the tidal flat that receives fluvial inputs. Zinc is the element with the highest EF values, followed by the order of Pb > Cd > Mn > Cu and Cr. The temporal variations of the heavy metals peak during the late 1980s to the early 2000s and show a decreasing trend afterward. The pollution intensity of the tidal flat is determined by using EF and the geo-accumulation index (Igeo), which show that, based on the Igeo scale, the tidal flat of Haizhou Bay is unpolluted to moderately polluted. 相似文献
775.
Influence of Chironomid Larvae on oxygen and nitrogen fluxes across the sediment-water interface (Lake Taihu, China) 总被引:7,自引:0,他引:7
The microscale distribution of oxygen,the nitrogen flux and the denitrification rates in sediment inhabited by chironomid larvae(Tanypus chinensis) were measured in eutrophic Lake Taihu,China.The presence of the chironomids in the sediment increased the oxygen diffusional flux from 10.4 ± 1.4 to 12.7 ± 2.5 mmol O 2 /(m 2 ·day).The burrows of the larvae represented "hot spots" and strongly influenced the nitrogen cycles and diagenetic activity in the sediment.The results indicate that the bioturbation effects of Tanypus chinensis chironomid larvae increased the capacity of the sediment as a sink for nitrate and a source for ammonium.Nitrate influx and ammonium outflux were increased 8.8 and 1.7 times,respectively.Under bioturbation,the amount of nitrate consumed was greater than the amount of ammonium released.The total denitrification rate was also enhanced from 0.76 ± 0.34 to 5.50 ± 1.30 mmol N/(m 2 ·day).The net effect was that the bioturbated sediments acted as a net sink for inorganic nitrogen under direct and indirect bioturbation effects compared to the control. 相似文献
776.
Speciation of organic phosphorus in a sediment profile of Lake Taihu I: Chemical forms and their transformation 总被引:2,自引:0,他引:2
Organic phosphorus(nonreactive P,NRP)is a major component of P in sediments,but information about its chemical forms and dynamic transformation is limited.The chemical forms and dynamic behaviors of NRP in a sediment profile from Lake Taihu,a freshwater and eutrophic lake in China,were investigated.Five forms of NRP in the sediments were extracted based on a chemical fractionation technique,including easily labile NRP(NaHCO3-NRP),reactive metal oxide-bound NRP(HCl-NRP),humic acid-associated NRP(NaOH-NRPHA),fulvic acid-associated NRP(NaOH-NRPFA)and residual NRP(Res-TP).There were notable transformations with increasing sediment depth from the labile NaHCO3-NRP and NaOH-NRP pools to the recalcitrant HCl-NRP and Res-TP pools,which caused the NRP to become increasingly recalcitrant as the early diagenetic processes proceeded.Further analyses showed that the relative changes in contents of organic matter and reactive Fe oxides in the sediment profile triggered a competition for binding NRP fractions and led to the transformation of NRP.The results highlighted the importance of abiotic processes in regulating the diagenesis of organic P and its stability in sediments. 相似文献
777.
778.
利用蒸馏装置蒸出钢渣中的氯离子,使用硝酸汞滴定方法进行滴定,选用两种钢渣,在不同实验室分别进行了分析测定的比较和验证。结果表明:该方法简便易操作,重现性和准确性都比较高,作为钢渣中氯离子的测定是可行的。 相似文献
779.
To use the selective inhibition method for quantitative analysis of acetate metabolism in methanogenic systems,the responses of microbial communities and metabolic activities,which were involved in anaerobic degradation of acetate,to the addition of methyl fluoride(CH3F),2-bromoethanesulfonate(BES)and hydrogen were investigated in a thermophilic batch experiment.Both the methanogenic inhibitors,i.e.,CH3F and BES,showed their effectiveness on inhibiting CH4 production,whereas acetate metabolism other than acetoclastic methanogenesis was stimulated by BES,as reflected by the fluctuated acetate concentration.Syntrophic acetate oxidation was thermodynamically blocked by hydrogen(H2),while H2-utilizing reactions as hydrogenotrophic methanogenesis and homoacetogenesis were correspondingly promoted.Results of PCR-DGGE fingerprinting showed that,CH3F did not influence the microbial populations significantly.However,the BES and hydrogen notably altered the bacterial community structures and increased the diversity.BES gradually changed the methanogenic community structure by affecting the existence of different populations to different levels,whilst H2 greatly changed the abundance of different methanogenic populations,and induced growth of new species. 相似文献
780.