三峡库区树坪滑坡变形特征及其诱发因素研究

三峡库区树坪滑坡为典型的古崩滑堆积型滑坡,自2003年三峡水库蓄水以来其变形明显.本文采用两步聚类法对树坪滑坡的监测数据进行了定性化处理,并在此基础上采用Apriori算法研究了该滑坡的变形特征及其与诱发因素之间的关系.结果表明:库水位是引起树坪滑坡位移变形的主要诱发因素,且该滑坡因每年库水位的升降而呈现周期性的变形特征;降雨是引起树坪滑坡位移变形的次要诱发因素,随着库水作用下滑坡体原有裂隙的扩张及产生新的裂隙,降雨对滑坡变形的影响将逐渐增强.     

长期施用有机和无机肥对黑土nirS型反硝化菌种群结构和丰度的影响

利用末端限制性片段长度多态性(T-RFLP)和实时荧光定量PCR(real-time quantitative PCR,Q-PCR)技术,结合反硝化潜势(DEA)和土壤理化性质的测定,探索了长期施用有机和无机肥对公主岭黑土nirS型反硝化细菌的群落结构和丰度的影响.试验设不施肥(CK)、单施有机肥(OM)、单施无机肥(NPK)以及有机肥和无机肥混施(MNPK)等4个处理.结果表明,长期施用有机肥显著增加了土壤的DEA,其中OM、NPK和MNPK处理分别为CK处理的5.92、1.81和6.03倍,而NPK和CK间无差异.有机肥处理增加了黑土nirS型反硝化细菌的丰度,OM、NPK和MNPK处理中nirS基因的拷贝数分别为CK的2.73、1.30和3.98倍;NPK处理对nirS基因的拷贝数影响不显著.T-RFLP图谱显示施用有机肥改变了nirS反硝化细菌的群落结构;相比于非有机肥处理,有机肥处理中增加了一类79 bp的片段类型,显著降低了84 bp的片段类型,并完全抑制了一类99 bp的片段类型,而有机肥处理间和非有机肥处理间的nirS群落结构分别相似.系统发育分析表明:黑土中nirS型反硝化菌主要由α、β和γ-变形菌纲及一些尚未培养的微生物组成,79 bp的片段类型与γ-变形菌纲的假单胞菌科(Pseudomonadaceae)和β-变形菌纲的伯克氏菌目(Burkholderiales)相似,84 bp片段类型与Burkholderiales和红环菌目(Rhodocyclales)相似.相关性分析表明,pH、全磷(TP)、全氮(TN)、总有机碳(TOC)、硝态氮(NO3--N)和铵态氮(NH4+-N)依次与nirS型反硝化细菌的种群丰度(r为0.724～0.922,P<0.05)和DEA(r为0.453～0.938,P<0.01)显著相关,DEA与nirS型反硝化细菌的种群丰度显著线性正相关(r=0.85,P<0.01);冗余度分析表明,除含水量外,TN、TP、pH、TOC、NH4+-N和NO3--N(r为0.440～0.862,P<0.01)依次与nirS型反硝化细菌群落结构的变化显著相关,DEA的变化和nirS型反硝化细菌群落结构的变化亦显著相关(r=0.863,P<0.01).本研究表明相比于无机肥处理,公主岭黑土中nirS型反硝化菌的群落结构与丰度对有机肥处理有更显著的响应,且其群落结构的改变与种群丰度的增加与DEA的提高显著相关.     

油菜/玉米轮作农田土壤呼吸和异养呼吸对秸秆与生物炭还田的响应

土壤呼吸是农田生态系统碳排放的主要途径,为研究土壤呼吸、其组分和水热因子对秸秆与生物炭还田的响应,在重庆国家紫色土肥力与肥料效益长期监测基地采用根系排除法联合运用土壤呼吸自动监测系统(ACE-002/OPZ/SC)测定了无物料还田(CK)、秸秆还田(CS)、秸秆+速腐剂还田(CSD)、生物炭还田(BC)、秸秆+生物炭1∶1还田(CSBC)5种处理下的紫色土丘陵区油菜/玉米轮作制中油菜和玉米生长季的土壤呼吸及其水热因子,并计算了根系呼吸贡献.结果表明,秸秆与生物炭还田显著影响土壤呼吸季节性变化特征和峰值,除BC处理外,其他处理均促进了土壤呼吸和碳排放;油菜季土壤呼吸呈单峰曲线,在0.12~2.29μmol·(m~2·s)~(-1)波动,不同处理土壤呼吸差异显著,表现为CSCSDCSBCCKBC处理;玉米季各处理土壤呼吸变化较复杂,变化范围为1.02~15.32μmol·(m~2·s)~(-1),其中CS、CSD和CSBC呈双峰型曲线,CK和BC呈单峰曲线.土壤异养呼吸能够解释土壤总呼吸变化的86.50%~93.94%,各处理的玉米季根系呼吸贡献(26.49%~32.86%)显著低于CK处理(53.65%).土壤呼吸速率的变化主要受5cm土壤温度控制,与土壤含水量无显著关系;5cm土壤温度能够解释土壤呼吸季节变化的82%~94%.土壤呼吸的温度敏感性系数Q10值在3.28~4.47之间,与CK处理相比,CS、CSD、CSBC处理的Q10分别降低了26.62%、18.12%、20.58%;而BC处理则增大了12.53%.水热双因子对土壤呼吸不存在协同作用,仅用土壤温度单因子指数函数可较好地模拟土壤呼吸速率的动态变化.可见,秸秆、秸秆+速腐剂和秸秆+生物炭还田显著促进了土壤呼吸,生物炭还田抑制了土壤呼吸.     

Catalytic removal of phenol from gas streams by perovskite-type catalysts

Three perovskite-type catalysts prepared by citric acid method are applied to remove phenol from gas streams with the total flow rate of 300 mL/min, corresponding to a GHSV of10,000/hr. LaMnO_3 catalyst is first prepared and further partially substituted with Sr and Cu to prepare La_(0.8)Sr_(0.2)MnO_3 and La_(0.8)Sr_(0.2)Mn_(0.8)Cu_(0.2)O_3, and catalytic activities and fundamental characteristics of these three catalysts are compared. The results show that phenol removal efficiency achieved with La_(0.8)Sr_(0.2)Mn_(0.8)Cu_(0.2)O_3 reaches 100% with the operating temperature of 200°C and the rate of mineralization at 300°C is up to 100%, while the phenol removal efficiencies achieved with La_(0.8)Sr_(0.2)MnO_3 and LaMnO_3 are up to 100% with the operating temperature of 300°C and 400°C, respectively. X-ray photoelectron spectroscopy(XPS) analysis shows that the addition of Sr and Cu increases the lattice oxygen of La_(0.8)Sr_(0.2)Mn_(0.8)Cu_(0.2)O_3, and further increases mobility or availability of lattice oxygen. The results indicate that La_(0.8)Sr_(0.2)Mn_(0.8)Cu_(0.2)O_3 has the best activity for phenol removal among three catalysts prepared and the catalytic activity of phenol oxidation is enhanced by the introduction of Sr and Cu into LaMnO_3. Apparent activation energy of 48 k J/mol is calculated by Mars–Van Krevelen Model for phenol oxidation with La_(0.8)Sr_(0.2)Mn_(0.8)Cu_(0.2)O_3 as catalyst.     

清淤底泥处置中添加粉煤灰/炉渣对重金属生物有效性及毒性的影响

在清淤底泥中添加碱性粉煤灰、燃煤炉渣进行钝化处理后,通过浸出毒性实验、重金属形态分级实验及植物生长实验对底泥基质中重金属的活性及生物有效性进行了研究.结果表明:清淤底泥中添加粉煤灰、燃煤炉渣等碱性物质后显著降低了底泥基质中可溶态重金属含量,其中,交换态、有机结合态Pb、Zn所占比例显著降低;碱性物质的加入缓解了重金属的浸出危害,钝化底泥基质中粉煤灰、炉渣对Cu的稳定率可达90.34%~96.88%;与此同时也抑制了底泥中重金属在植物体内的富集与迁移,降低了重金属的生物有效性.相关性分析表明,底泥基质中交换态重金属含量、浸出浓度、植物茎叶中重金属含量及植物根伸长抑制率之间存在显著正相关关系(p0.01).     

Soil Carbon Sequestration Potential for “Grain for Green” Project in Loess Plateau,China

Conversion of cropland into perennial vegetation land can increase soil organic carbon (SOC) accumulation, which might be an important mitigation measure to sequester carbon dioxide from the atmosphere. The “Grain for Green” project, one of the most ambitious ecological programmes launched in modern China, aims at transforming the low-yield slope cropland into grassland and woodland. The Loess Plateau in China is the most important target of this project due to its serious soil erosion. The objectives of this study are to answer three questions: (1) what is the rate of the SOC accumulation for this “Grain for Green” project in Loess Plateau? (2) Is there a difference in SOC sequestration among different restoration types, including grassland, shrub and forest? (3) Is the effect of restoration types on SOC accumulation different among northern, middle and southern regions of the Loess Plateau? Based on analysis of the data collected from the literature conducted in the Loess Plateau, we found that SOC increased at a rate of 0.712 TgC/year in the top 20 cm soil layer for 60 years under this project across the entire Loess Plateau. This was a relatively reliable estimation based on current data, although there were some uncertainties. Compared to grassland, forest had a significantly greater effect on SOC accumulation in middle and southern Loess Plateau but had a weaker effect in the northern Loess Plateau. There were no differences found in SOC sequestration between shrub and grassland across the entire Loess Plateau. Grassland had a stronger effect on SOC sequestration in the northern Loess Plateau than in the middle and southern regions. In contrast, forest could increase more SOC in the middle and southern Loess Plateau than in the northern Loess Plateau, whereas shrub had a similar effect on SOC sequestration across the Loess Plateau. Our results suggest that the “Grain for Green” project can significantly increase the SOC storage in Loess Plateau, and it is recommended to expand grassland and shrub areas in the northern Loess Plateau and forest in the middle and southern Loess Plateau to enhance the SOC sequestration in this area.     

Characteristics of major secondary ions in typical polluted atmospheric aerosols during autumn in central Taiwan

In autumn of 2008, the chemical characteristics of major secondary ionic aerosols at a suburban site in central Taiwan were measured during an annually occurring season of high pollution. The semicontinuous measurement system measured major soluble inorganic species, including NH(4)(+), NO(3)(-), and SO(4)(2-), in PM(10) with a 15 min resolution time. The atmospheric conditions, except for the influences of typhoons, were dominated by the local sea-land breeze with clear diurnal variations of meteorological parameters and air pollutant concentrations. To evaluate secondary aerosol formation at different ozone levels, daily ozone maximum concentration (O(3,daily max)) was used as an index of photochemical activity for dividing between the heavily polluted period (O(3,daily max) ≧80 ppb) and the lightly polluted period (O(3,daily max)<80 ppb). The concentrations of PM(10), NO(3)(-), SO(4)(2-), NH(4)(+) and total major ions during the heavily polluted period were 1.6, 1.9, 2.4, 2.7 and 2.3 times the concentrations during the lightly polluted period, respectively. Results showed that the daily maximum concentrations of PM(10) occurred around midnight and the daily maximum ozone concentration occurred during daytime. The average concentration of SO(2) was higher during daytime, which could be explained by the transportation of coastal industry emissions to the sampling site. In contrast, the high concentration of NO(2) at night was due to the land breeze flow that transport inland urban air masses toward this site. The simulations of breeze circulations and transitions were reflected in transports and distributions of these pollutants. During heavily polluted periods, NO(3)(-) and NH(4)(+) showed a clear diurnal variations with lower concentrations after midday, possibly due to the thermal volatilization of NH(4)NO(3) during daytime and transport of inland urban plume at night. The diurnal variation of PM(10) showed the similar pattern to that of NO(3)(-) and NH(4)(+) aerosols. This indicated that the formatted secondary aerosols in the inland urban area could be transported to the coastal area by the weak land breeze and deteriorated the air quality in the coastal area at night.     

高温作业人员的防护措施

正常气温对人体是必需的、有益的。高温则会引起中暑。当环境受热明显超过散热时,机体则会出现热蓄积;当热蓄积超过了体温调节能力,则出现过热、中暑,甚至死亡。本文从佩戴个体防护用品、技术措施等角度,提出了预防高温作业人员受到职业危害的具体措施。     

Photocatalytic degradation of phenol on different phases of TiO(2) particles in aqueous suspensions under UV irradiation

Photocatalytic degradation of phenol on different phases of TiO₂ particles was examined under 400-W UV irradiation. The effects of various operating parameters including TiO₂ dosage, solution pH (4–10), and initial phenol concentration (0.13–1.05 mM) on phenol degradation were investigated. Three forms of TiO₂ photocatalysts such as pure anatase phase, pure rutile phase, and the mixed phase were prepared by sol-gel method and followed annealing at different temperatures. The annealing temperature used were 500 °C, 700 °C and 900 °C for pure anatase phase, the mixed phase, and pure rutile phase, respectively. It was shown that pure anatase TiO₂ exhibited higher photocatalytic activity than the physical mixture of pure anatase and rutile TiO₂. Moreover, the TiO₂ particle with a specific fraction of mixed anatase and rutile phases exhibited better performance than pure anatase TiO₂. Finally, the degradation rate could be satisfactorily fitted by a pseudo-first-order kinetic model.     

Effects of varying dilutions, pH, temperature and cations on spermatozoa motility in fish Larimichthys polyactis

The objectives of this present study were to assess the effects of varying dilutions, pH, temperature and cations on spermatozoa motile parameters (SMPs) in fish Larimichthys polyactis. Optimal SMPs were observed when emen was diluted in artificial seawater (ASW) at a ratio of 1 to 100, with temperature of 10 degreesC and pH 8.0. The spermatozoa of L. polyactis were immotile in distilled water and motile in solution containing different cations. Maximum SMPs were obtained in each solution containing 0.4 mol NaCI, 0.4 mol KCI, 0.2 mol CaCI2 and 0.2 mol MgCl2. This study provides baseline knowledge of L. polyactis spermatozoa sensitivity of pH, temperature and cationic effects.