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干旱及复水过程中胡杨气孔行为研究
No full textStomata play a key role in regulation the trade-off between photosynthesis andtranspiration. Drought stress may reduce evaporation rate at the cost of carbon assimilationloss through stomatal closure, which suggests that stomatal regulation is critical to balancewater and carbon under different soil moisture conditions. As the constructive species ofTarim desert riparian forests in northwestern china, Populus euphratica is subject tofrequent groundwater fluctuations due to the variations in runoff, which gets P.euphratica,especially for seedlings established on the sediments close to active channel, frequentlysuffer from drought in dry seasons and re-watering after flooding events. Currently little isknow about the role of stomatal behavior of P.euphratica in adapting to such frequentfluctuations in water environments. The dominant species of P.euphratica was chosen inthis study. In this study, we measured photosynthesis responses to CO2, cholorophyllfluorescence, water status and hydraulic architecture parameters for 3 years oldP.euphratica seedling during a progressive drought as well as re-watering. Then thestomatal and non-stomatal limitations for photosynthesis of P.euphratica were analysedduring the progressive drought and after re-watering.The results indicated that, when the xylem water potential decreased to -0.41 MPa forseedling experiencing 11 d drought, the transpiration rate (Tr), electron transport rate(ETR), respiration rate (Rd), stomatal conductance (gs), mesophyll conductance (gm),photospiration rate (Pr), substomatal CO2 concentration (Ci), chloroplast CO2 concentration(Cc) and maximum capacity for carboxylation (Vcmax) decreased while water use efficiency (WUE) increased and the carbon assimilation rate was maintaineds at a high level. At thisearly drought stage, biochemical limitation (BL) was the major limitation to photosynthesis.With the xylem water potential decreasing from -1.28 MPa after 47 d drought, the WUE,Pr and Rd increased, the gs, gm, ETR, Vcmax, Ci, Cc and Tr exhibited varying decease, whichsuggests that shown carbon assimilation mainly limited by SL at this stage. The xylemwater potential further decreasing to -1.52 MPa after 79 drought, the WUE, gs, Tr, ETR, gm,Vcmax, Pr and Rd continued to decrease while Ci and Cc increase, showing a important roleof MCL in maintaining low carbon assimilation rate at this stage. Overall, results theprogressive drought experiment show that, under light drought stress, P.euphraticaseedling are able to maintain high carbon assimilation rate through WUE injustment, withBL as the major limitation on photosynthesis. Under medium drought stress, the reduced gsand carbon assimilation rate along with increased WUE suggest that carbon assimilation islimited by SL. Under severe drought stress, An was mainly limited by MCL, evidenced bydecreased WUE and carbon assimilation rate.For seedlings rewatered at a xylem water potential of -0.98 MPa, Vcmax recoveredcompletely while An unlimited by BL at the time, recovered to 52.98% relative to thecontrol on the 1st day after re-watering. The gs and gm recovered almost completely on the4th day after re-watering, at the time An was 99.35% relative to the control and not limitedeither by SL or by MCL. During the re-watering period, PLC was negatively related to gsand An. For seedlings rewatered at the xylem water potential of -1.52 MPa, Vcmax totallyrecovered while An was restored to 48.78% of the control on 2nd day after re-watering,without limitation by BL. The gm recovered to 93.70% of the control on the 4th day afterre-watering, showing no MCL limitation on An. The gs recovered only to 56.17% of thecontrol on the 5th day after rewatering, showing a major limitation of SL on An. Severelydroughted seedlings under rewatering showed a negative relationship between gs, An andPLC but a positive one between gs, An and KL, KS. In conclusion, results of re-wateringexperiment show that An of the moderately-droughted seedling is little limited by SL, MCLand BL after re-watering, leading to a rapid recovery of An. SL was the major limitation on An for severly droughted seedlings when rewatered. The recovery of PLC, KS and KL maycontribute to the recovery of An in P.euphratica. Furthermore, comparing recovery of Anand limlit factors to photosynthesis under different degrees of drought stress afterre-watering, which find that the realtively rapid recovery of carbon assimilation forP.euphratica seedling that the main reason were quickly recovery of MCL and BL underrewatering
荒漠城市生态系统对未来气候变化响应的模拟研究与可持续评估
No full text作为人类活动的热点区域，城市突出反映了人类对自然环境的改造和控制；城市区域内大规模的物质生产、消费活动正在（或已经）改变陆地表面覆被状况、生物
气候变化与人类活动对阿姆河流域水资源及咸海退缩的影响研究
No full text气候变化与人类活动的影响研究是目前流域水文水资源演变规律研究的两大课题。特别是对于全球变化较敏感的干旱、半干旱区域，气候变化与人类活动对水文水资源的影响比较显著。作为气候系统的重要组成部分，水循环系统与水资源的时空变化必然会受到气候变化的影响。人类活动一方面通过，改变土地利用/土地覆被，改变流域下垫面，破坏了流域天然的产汇流机制影响流域水资源的时空变化；另一方面通过工农业用水或跨流域调水等活动直接改变流域水资源的时空分布特征。本文针对咸海流域的水资源变化问题，采用统计分析和模型模拟相结合的方法，根据阿姆河流域的水文水资源特征，水利设施基本情况和土地资源开发利用现状和气象要素的变化情况，全面分析了阿姆河整个流域的耗水过程，水资源量、耗水量、灌区面积变化和咸海变化的关系。并模拟分析了气候变化和人类活动特别是灌溉农业用水量和灌溉水利用效率对流域水资源和咸海退缩的影响。本文的研究成果如下：1）阿姆河上游的径流量变化趋势主要与上游气象要素的变化相关。降水量和径流量从 19 世纪 50 年代到 70 年代初减少，从 70 年代初到 90 年代末增大，2000 年以后开始减少。气温具有增长趋势，从 1990 年开始气温变化更显著。中下游的径流量变化主要与土地资源开发和修建水利设施，农业灌溉用水等人类活动相关，受气候变化的影响很小。阿姆河中下游的耗水量从 70 年代开始迅速增长，2000 年以后有所减少。1982、1986、2000、2001、2008 年几乎耗尽了上游的来水量。分段耗水量分析结果表明，阿姆河中下游的耗水量在整个流域的耗水量中占 60%以上，中游和下游的耗水量变化趋势基本一致。下游的耗水量受河流水量丰枯变化的影响大于中游。阿姆河中下游的灌溉面积从 1970 年开始迅速增长，1990 年的面积约等于 1970 年的 2 倍。1990 年以后灌区面积缓慢增长，2000 年由于缺水 14%耕地弃耕。虽然 2010 年的灌区面积在 1990 年的基础上增长了 29%，耗水量却减少了 7%。这主要是因为单位面积灌溉水量的减少，灌溉定额从 970 年的 26538 m3/ha/年减少到 2010 年的 14243 m3/ha/年。2）阿姆河上游来水量、中下游耗水量、灌区面积及咸海的变化趋势分析结果表明咸海退缩的主要原因是以灌溉农业为主的人类活动而不是气候变化。咸海的水量从1970 年以后迅速减少，2000 年的水量只占 1950 年水量的 10%。中下游的径流量从1970 年开始迅速减少而上游水量具有增长趋势。这与灌溉农业的发展趋势基本一致。3）基于 SWAT 模型的阿姆河上游气候变化对径流量的影响研究结果显示，阿姆河上游的历史径流量具有微弱的增长趋势；径流量在 GCMs 的最低排放情景下，2021-2060 年在基准期 1965-2004 年的基础上增长了 2%；洪峰在历史时期的气候变化和未来气候变化情景下都具有显著的减少趋势。在未来气候变化情景下洪峰出现时间提前了一个月。4）阿姆河中下游的模拟结果显示，阿姆河下游受到上游来水量的影响大于阿姆河中游（从基准期到 1973-1992 年的影响量分别为-148.58 和-170.14 亿立方米）。气候变化对阿姆河中游和下游流量的贡献都为正值，而且这种影响从 70 年代到现在逐渐减弱。从基准期到 1972-1991 人类活动对阿姆河中游和下游的贡献量分别为-31.24 亿和-13.27 亿立方米。基准期到 1992-2010 年人类活动对阿姆河中游和下游的影响量分别为 10.73 和 11.04 亿立方米。阿姆河中游、下游在 1972-1991 和 1992-2010 两个时间段的灌溉影响量分别为 83.29 和 62.26 亿立方米，146.00 和 172.40 亿立方米。在 3种灌溉效率提高情景对下游的影响大于中游。1972-1991 年提高灌溉效率对中游的影响大于 1992-2010 年的影响，说明 1976-1991 年中游受灌溉水量的影响大于 1992-2010年。对于下游，1992-2010 年的影响大于 1976-1991 年的影响。这主要是因为下游的灌溉人类活动对径流量的影响大于中游。通过上述研究可以深入了解，气候变化和人类活动对阿姆河流域水文水资源及咸海退缩的影响规律及未来的变化趋势，可为阿姆河流域的水资源管理，土地资源管理和生态环境保护提供理论依据
典型荒漠植物叶片和冠层蒸腾高光谱遥感研究
No full text植物蒸腾反映植物耗水情况与生理状态，是区域能量平衡和水量平衡的重要组成部分。在干旱区，准确掌握荒漠植物蒸腾动态是理解干旱区水循环和监测荒漠生态系统稳定性的重要途径。本研究针对传统的植物蒸腾速率的获取方法耗时耗力，无法实现快速动态监测等缺点，以典型荒漠植物梭梭（Haloxylon ammodendron）为研究对象，开展植物蒸腾、高光谱反射信息、植物生化物理等参数及环境因子的野外同步观测实验。基于野外同步实测数据，结合统计方法（指数法、PLSR 法）与 SCOPE 机理模型，研究探讨了不同尺度（叶片和冠层）植物蒸腾的高光谱遥感反演方法，得到的研究成果如下：（1）研究提出了结合 EFAST 全局敏感性分析方法和多目标优化的 SCOPE 模型校正方法。对 SCOPE 模型的敏感性分析结果表明，在 460 nm，675 nm 和 1900 nm附近的冠层反射率受植物生理参数的一定影响，可能与植物蒸腾等生理过程存在联系。研究改进和校正的 SCOPE 模型能够较准确模拟荒漠植物冠层反射信息（R2 >0.9）、冠层蒸腾（R2 > 0.6），及净辐射（R2 > 0.9）。（2）对同步实测数据的植物蒸腾高光谱遥感分析结果表明：一阶导数光谱相比原始反射率在荒漠植物蒸腾估算中的精度更高，尤其是在包含强土壤背景噪声的冠层尺度。研究基于一阶导数光谱，分别构建了叶片和冠层尺度蒸腾最优光谱指数和 PLSR模型。在叶片尺度，基于一阶导数光谱的最优指数 dND(1020, 1900) 估算的叶片蒸腾与实测值之间的决定系数为 0.33，而基于 9 个波段（2210，2215，1980，2205，2000，2140，435，2375 和 2345 nm）一阶导数光谱建立的 PLSR 模型估算的叶片蒸腾与实测值之间的决定系数为 0.71。在冠层尺度，基于一阶导数光谱的最优指数 dSR(660,1040)估算的冠层蒸腾与实测值间的决定系数为 0.53，而基于 7 个波段（670，1195，2190，915，2425，2365 和 2205 nm）导数光谱建立的 PLSR 模型估算的冠层蒸腾与实测值间的决定系数分为 0.78。（3）为解决基于实测数据的植被参数估算统计模型因数据量有限，存在普适性差的问题，研究提出了结合 SCOPE 模拟数据库与野外实测数据集的冠层蒸腾高光谱指数开发方法。结合模拟数据库和实测数据集得到的高光谱指数在实测数据集和模拟数据库中蒸腾估算具有较好的一致性，基于一阶导数光谱的 dSR(660, 1040)指数对实测数据集和模拟数据库中蒸腾估算 R2 分别为 0.54 和 0.50。同时，该指数也是在 10 nm光谱间隔下的最优光谱指数。因此，dSR(660, 1040)指数可为利用 Hyperion 及 AVIRIS等高光谱影像产品进行大范围植物蒸腾遥感监测提供参考。本研究建立了高光谱技术估算荒漠植物蒸腾的新途径，研究成果可为高光谱遥感技术在干旱荒漠生态安全与稳定的监测应用提供技术支持和科学理论依据
艾比湖流域沉积物元素地球化学特征及其揭示的环境信息
No full textSoil is an important basis material for the survival of plants and animals on the earth. It is also an important resource for the development of human production. Element as an important component of soil, its natural content depends on the natural factors such as parent material, soil formation, topography, regional climate, biology and other natural factors. Lake sediments are faithful records of the natural environment evolution (climate, hydrology) and information of human activities in different periods. The elements in the soil of the river basin are imported into the lake under the action of erosion and transportation, and are deposited on the bottom of the lake. The changes in the records of its material sources, the degree of geochemical weathering and erosion, the intensity of human activities, regional climate change and the history of lake geochemical evolution are important indicators of regional environmental change. Therefore, in this study, physicochemical proxies (focus on elements) of sediment core in Ebinur Lake are studied, statistical analysis, the semi-variance function model, IDW method and potential ecological risk index method are using to analyze the elements spatial heterogeneity and influence factors of elements in topsoil are also analyzed; using enrichment factor correction method, sequential clustering analysis method to analyze the geochemical characteristics and the environment evolution history, heavy metal pollution history of watershed are also analyzed. This study, in order to give basic scientific guides for the coordinated development of the regional ecological environment and human society, a basic information of the regional environmental change and its response to human activities in Ebinur Lake basin. The main conclusions are listed as follows:（1） Descriptive statistics of element concentrations in topsoil showed: The average contents of Ba, Mn, V, Pb, Cr, Co, Ni, Cu in the topsoil of Ebinur Lake were lower than those of Xinjiang soil background value, while other elements of the average value are higher. The spatial distribution of the contents of elements Ca, Mg, Na, Sr, Ni and Cd shows the most obvious difference from medium to strong variability, while the other elements shows weak variability. The high value area of most elements is mainly located in the fields of farmland, traffic trunk, river and urban residential areas, which indicates that the distribution of surface elements in the study area is affected by human activities and local environment.（2） The environmental proxies of particle size, total organic carbon and elements in Ebinur Lake shows that there are two obvious differences at the deep of 23cm (1960 AD):the content of each environmental proxy was lower and changed small before 1960; after 1960, the content suddenly increased and fluctuated significantly, especially heavy metals Co, Cr, Cu, Ni, Pb, V, Zn and so on.（3） The influence factors of elements in topsoil were analyzed by classical statistical and geostatistics analysis, which shows that elements Al, Fe, K, Ti, Ba, Be, Mn, V,Ti, Ba and so on have a medium to strong spatial autocorrelation and the spatial structure of the element P and the heavy metal elements Zn, Pb, Ni and Cu are more complicated due to random factors such as tillage fertilization, transportation, industrial and agricultural production. Elements Ca、 Sr、 Mg have a strong active geochemical characteristic, in addition to under the influence of regional soil parent material, and easily influenced by local factors lead to complicated spatial structure. Cd is a heavy metal element, however, it is divided into the same class with Ca, Sr and other activity chemical elements, which may be affected by the man-made industrial and agricultural activities, traffic and other anthropogenic resulting in large differences of the distribution and strong spatial variability in the study area, then there is no spatial autocorrelation at the sampling scale. Element Na shows a poor spatial structure due to the regional natural environment changes and the impact of man-made farming.（4） Elements in sediment core are divided into three assemblage: Fe, Mn, V, Ni, Li,Cr, K, Al, Co, P, Ti, Be, Pb, Cu, Ba and Zn are mainly derived from watershed terrestrial debris, and the content of those elements are mainly affected by the watershed erosion intensity. Among them, the changes of heavy metals Co, Cr, Cu, Ni, Pb, V, Zn and nutrient P were nearly different in the past 150 years. The ordered specimen cluster analysis method was applied to study the lake environmental changes base on the enrichment factors of heavy metals and P. The results show that the environmental evolution history nearly 150 years can divide into two distinct stages taking 23 cm (1960) as the boundary in the Ebinur Lake basin:Stage I. From 1875 to 1960 AD, at this stage the level of social development of the basin is low, human activities lead to less input of heavy metals, the basin environment is mainly affected by regional natural changes;Stage II. From 1960 ~ Present, with the increase of population, economic development,industrial and agricultural activities increased, especially agricultural water consumption increased, most of the heavy metal elements and P relative to the early have a more obvious increase. The second type of elements includes Mg and Na, mainly from the evaporation of salt crystals in lake water. Due to the development of oasis agriculture and the increase of irrigation water, the lake water level fluctuates violently under the influence of climate change and human activities which lead to the fluctuations Mg, Na and other elements. The third class elements include Ca and Sr, which are controlled by the weathering leaching of readily soluble elements in the watershed （5） The enrichment coefficient and the potential ecological risk assessment show that most of the heavy metal elements in the topsoil of the basin have been affected by human activities, and the enrichment of Cd is most obvious, its Eri value is up to 287.6 which means a highly potential ecological risk; followed by Ni and Cu, Ni Eri value of up to 25.7; Overall, 8 kinds of heavy metal elements in the topsoil comprehensive potential ecological risk (RI) average is 85.5 showing a slight ecological risk. And most of the high RI value areas are located in the main road, farmland and urban areas where human activities are relatively intensive. The accumulation of heavy metals in lake sediments core is lower than that in topsoil, although the accumulation of heavy metals has increased since 1960, but the total cumulative index and potential ecological risk are lower. The results showed the potential ecological risk of elements in sediment core followed the order: Ni(4.7)＞Pb(4.6)＞Cu(4.2) ＞Co(2.6)＞Cr(1.7)＝V(1.7)＞Zn(1.1), and the potential ecological risk of those heavy metals were slight
古尔班通古特沙漠南缘梭梭树干液流特征与林分蒸腾规律
No full textThe transpiration water consumption of Haloxylon ammodendron is an importantphysiological index, and its variation law is influenced by many environmental factorscomprehensively. The transpiration water consumption of individual trees could beaccurately measured by investigating the characteristics of sap flow andenvironmental factors, and the transpiration of single-tree also could be predicted withthe help of environmental indicators by building the modeling with the sap flow andenvironmental factors. Combined with automatic weather stations, thermal dissipationprobe (TDP) was continuously used to measure the sap flow dynamics andenvironmental factors of Haloxylon ammodendron in the southern marginal zone ofthe Gurbantunggut desert, the sap flow velocity response to the environmentalelements were analyzed and the stem sap flow of Haloxylon ammodendron weresimulated based on the potential evapotranspiration and transpiration requirementindex . The results showed that:(1) The change of sap flow velocity mainly presented single peak or occasionallyappeared double peak curve in summer. The amplitude of daily variation and sap flowpeak in summer were greater than in the spring and autumn and presented asignificant differences with the sap-flow velocity during different seasons. Thestarting and peak times of sap flow were earlier and had a weak sap flow at night insummer. (2) In the growing season, net radiation, air temperature and saturated vapor pressuredeficit were the key factors of leading to the instantaneous changes. The instantaneoussap-flow of Haloxylon ammodendron was positively correlated with wind speed, netradiation, saturated vapor pressure deficit and air temperature, and negativelycorrelated with the actual water vapor pressure and air humidity. The net radiation, saturated vapor pressure deficit and air temperature were the key factor affectting theseasonal change of sap flow velocity. The daily average flow rate was positivelycorrelated with the net radiation, air temperature,saturated vapor pressure (3) deficit,actual water vapor pressure, soil water content and soil temperature, and asignificant negatively correlated with the air humidity. (4) There were different degrees of correlation between environmental factors, Thefirst three axes of principal component analysis (PCA) explained 47%, 20%, 17.6% ofvariances in the environmental data sets, while the first principal component includingRH, Ta, VPD, ET0 and Rn could explain 47% of environmental information changes, the second principal component with Ts and ea could explain 20% of environmentinformation, the third principal component given priority to HS and u2 could explain17.6% of the environment change information. The first principal component reflectsthe needs of the atmosphere transpiration, and the second and third principalcomponents reflect the effect of soil environmental conditions on transpiration rate. (4) The accuracy of sigmoid based on potential evapotranspiration in spring andsummer was higher, and the polynomial model was better than the ET0 model inautumn. (5)The hysteresis between velocity of sap flow and environmental factors wererevealed, presented significant differences during different seasons. In spring andautumn, the relationship between the velocity of sap flow and VPD was clockwise, while the relationship between the velocity of sap flow and the net radiation or thepotential evapotranspiration presented a counterclockwise trend. As in the spring andautumn seasons, the relationship between the sap flow velocity and VPD alsopresented a trend of clockwise during summer, however, the relationship between thesap flow velocity and the net radiation or potential evapotranspiration presented aclockwise as figure 8. (6)The daily transpiration of Haloxylon ammodendron forest was 0.35 mm/d, totaltranspiration was 53.35 mm during the whole study period, The daily transpirationwas increased from April to July, then began to decrease until the end of the growingperiod
和田地区人口发展变化特征及其对区域发展的影响研究
No full textPopulation-related issues such as population growth, population structure,population development, demographic dividend and fertility policy have always beenissues in which community are interested and they are the focus for academicresearchers as well as. In recent years, the average growth rate of population in Chinahas been declining continuously, and the main contradiction of population haschanged from excessive growth to disappearing population bonus, low fertility andpopulation aging and so on. Affected by policies and the level of economicdevelopment, population problems in the minority areas such as Hotan were quitedifferent from those in most parts of the country, where population growth was stillfast, the age structure of the population, education structure and employment structureand so on were also unique. The contradiction between population and economicdevelopment and resources and environment was prominent. Population problem hasalways been one of the key problems that restrict their economic development.Population development was not only the condition of economic development, butalso the purpose of it. Therefore, it was of great significance to study the populationdevelopment in Hotan and explore its impact on regional development in thebackground of the implementation of The Belt and Road strategic and comprehensivetwo child policy. This article took Hotan's population as the research object. First, it introduced thebackground and significance of the topic, domestic and international populationresearch, the main research contents, the research methods and thesis framework.Second, it described and analyzed the condition and characteristics of populationdevelopment in hotan since the founding of China. Next, it built index system ofpopulation development level and had a quantitative analysis of populationdevelopment in hotan by entropy method. Then, it predicted the population growthtrend in hotan in 2010-2050. Based on the above study, it analyzed the relationshipsbetween population growth and economic development and resource environment. The main conclusions are as follows. First, the population in hotan had been growing fast and the natural growth ratefluctuated with the change of time. The age structure of the population changed fromyoung to adult, the gender structure was reasonable, the ethnic structure was single,the level of education structure, employment structure, urban and the rural structurewas low. Restricted by natural and economic conditions, population distributionvaried greatly in this region. What’s more, the land population density was low andthe oasis population density was very high. Second, the population development level and each subsystem of populationdevelopment showed a rising trend in Hotan on the whole. There was big differencebetween population development level in different counties and it was decreasing.Each subsystem of population development also showed a rising trend in every county.Subsystem of population development was unbalanced in the same county. Third, future population would change big in hotan and the natural growth ratewould decrease; Labor force would be rich and demographic dividend period wouldlast for a long time; age structure of the population would change from adulthood toold age and the population aging would be increasing. Fourth, the economy development gap existed in the whole xinjiang and withinthe region and was large. Population growth had a large influence on economicdevelopment in hotan. From the perspective of demographic dividend, populationresources were not fully utilized. It’s not adequate to realize the demographicdividend. What’s more, the faster the population grew, the greater the pressure oneconomic development. With the increase of population, pressure on Hotan's waterresources and land resources was relatively large and there would be a serious threatto food security
晚古生代伊犁地块北缘岩浆岩的成因及地质意义
No full textThe Central Asian Orogenic Belt is one of the typical accretionary orogens on theEarth, and represents the major site of the continental crust growth during the Phanerozoic.The Central Asian Orogenic Belt can be devided into three collage systems, i.g., Siberiaarctive continental margin collage systems, Tarim and North China cratons collage systems,and Kazakhstan collage system. The Kazakhstan collage system is located at thecombinative region between the other two collage systems, and is characterized by thetypical oroclinal bending structure. The northern Yili Block is situated inboard in thesouthern limb of Kazakhstan collage system with numerous igneous rocks and ore deposits,and thus retains a record of the bending processes of the Kazakhstan Orocline and theassociated evolution of the Junggar Ocean in the late Paleozoic. However, the latePaleozoic evolution of Junggar ocean, the terrane assembly process and continental crustgrowth in the northern Yili Block have been poorly constrained. This thesis focuses on theLate Paleozoic igneous rocks from the Borohoro and Alataw area in the northern YiliBlock. Detailed geological field investigations combined with petrology, mineralogy,geochronlogy, major and trace element, Sr-Nd-Hf-O isotope data are reported in this study,for the sake of investigating the petrogensis of these rocks, their temporal-spatialdistribution and associated geodynamic processes, identify the tectonic evolution andimplication for continental crust growth and formation of ore deposits. The majorconclusions are summarized as follow:（1）These granitoids are mainly monzogranite, K-feldspar granite and granodiorite.On the basis of the chronological study, these samples are subdivided into Group 1 with theage of the Late Devonian (374-369 Ma) and Group 2 with the age of the LateCarboniferous (ca.304 Ma). They have similar major and trace elements contents, butdistinct Sr-Nd-Hf isotopic compositions. Most of these granitoids show high-Kcalc-alkaline and metalumious affinities, and enriched in large ion lithophile elements(LILE) and depleted in high field strength elements (HFSE), and contain low Sr/Y(3.4-20.7) and Sr (96-431 ppm) values, indicating typical arc geochemical affinities. They have variable SiO2 (62.6-72.9 wt.%) and Fe2O3T (2.54-5.21 wt.%) contents, and Mg#(33-51) values. The Group 1 samples display slightly higher initial 87Sr/86Sr ratios(0.7075-0.7089) but lower εNd(t) (+0.3 to +0.9) values than those of Group 2 samples(87Sr/86Sr(i)= 0.7060-0.7066 and εNd(t)= +1.7 to +2.0). The Group 1 samples show the lowerεHf(t) (-3.62 to +6.79) values and older TCDM (0.90-1.61 Ga) than those of Group 2 samples(εHf(t) of +1.21 to +11.3 and TCDM of 0.56 to 1.25 Ga). These features suggest that thegranitoids were derived from a hybridized source of a juvenile materials (includecrust-derived and mantle-derived magmas) and an old metamorphic component, while theGroup 2 samples have greater contribution of juvenile materials.（2）The Nd-Hf isotopic compositions of granitic rocks from northern Yili Blockshow comparable zircon εHf(t)-time and whole-rock εNd(t)-time patterns with an abruptchange at ca. 360 Ma. During ca. 400-360 Ma igneous isotopic features are characterizedby a large spread of zircon εHf(t) values (-12 to +10) and whole-rock εNd(t) values (-5 to+5), and an overall decreasing trend with time, whereas ca.360-300 Ma igneous isotopicfeatures have mostly positive zircon εHf(t) values (+2 to +12) and whole-rock εNd(t) values(-2 to +8) and gradually increasing with time, suggesting a subduction tectonic switch froman advancing subduction of the Junggar oceanic plate to the retreating subduction wasidentified occurred at ca.360 Ma.（3）Combing the data from this study and published in the study area, showing thatgranitic rocks have high whole-rock εNd(t) and zircon εHf(t) values with the affinity ofdepleted source, which indicate the continental crust growth event. In the Hf isotopesystem, the modeling results show that during the 400-300 Ma, about 15-100 % juvenilematerials with varying degrees involved in the formation of granitic rocks, while in the Ndisotope system, the modeling results show that about 5-60 % juvenile materials withvarying degrees involved in the formation of granitic rocks during the 400-300 Ma.（4）For the ca. 300 Ma volcanism, the ignimbrites have low SiO2 (65.8-71.5 wt.%)and Mg# (6-13) values, and exhibit arc affinity with significantly enrichment of large ionlithophile elements (LILE) and depletement of high field strength elements (HFSE) such as Nb, Ta and Ti. The whole-rock εNd(t) and zircon εHf(t) values range from +6.9 to +7.0 and+9.9 to +14.1 respectively, indicating a juvenile basaltic lower crustal origin. Rhyoliteshave slightly high SiO2 (72.7-74.0 wt.%) and K2O (3.86-4.53 wt.%) contents, high zirconδ18O (11.67-13.23‰) values, and low whole-rock εNd(t) (+2.9 to +3.8) and zircon εHf(t)(+2.8 to +10.0) values, which may suggest sediment involvements during magmageneration. In contrast, for the ca. 288 Ma plutonism, the biotite granites have obviouslyhigher SiO2 (74.7-75.5 wt.%) contents and whole-rock εNd(t) (+7.7 to +8.8), zircon εHf(t)(+9.8 to +12.7), and lower zircon δ18O (5.99-6.84‰) values, than those of the ca. 300 Mavolcanic rocks, which are consistent with signatures of juvenile magma source.（5）The ca.300 Ma ignimbrites and rhyolites have high zircon whole-rock saturationtemperature (888-938℃ and 815-832℃), and high εHf(t) values, indicating an hightemperature magmatic event at ca. 300 Ma, we interpret this magmatic episode having alink with arc-continent collision/amalgamation of the West Junggar Terrane and Yili Block,which intrigued the asthenospheric upwelling through slab break-off. The ca.288 Mabiotite granites have low zircon whole-rock saturation temperature (723-735℃), withresidual amphibole in the source. Thus, we infer the subsequent strike-slipping of NorthTianshan Fault that facilitated introduction of water-fluxes triggering hydrous partialmelting of juvenile lower crust
生物炭与微生物联合修复金尾矿的汞砷污染
No full textXinjiang is rich in mineral resources and large in number of gold mines. The productof gold mining tailings has a huge amount, in which has high concentration of Hg2+ andAs3+. The open-air stacking lead to the migration of Hg2+ and As3+ with rain and snow, thatcaused serious environmental pollution and posed a threat to the ecosystem and humanhealth.However, there are few methods for handling tailings at present. Generally, it isopen-air stacking and has not been dealt with, which has a serious impact on the ecologicalenvironment. There are also few tailings dealt with cement, but which is expensive and isnot conducive to the reuse of tailings. In order to solve this situation, the research teamdeveloped new MICP technology to solidification tailings and was applied it to thesolidification experiments under laboratory conditions. But the effect of tailingssolidification is not ideal, mainly as follows: the unconfined compressive strength is nothigh, and the control effect of some heavy metals needs to be improved. Therefore, thisstudy is expected to enhance the effect of tailings solidification by biochar. Biochar is aneco-friendly material which has a good adsorption effect on heavy metals. We expect theaddition of biochar to enhance the strength of the curing and the effective control of theleaching of heavy metals. In this paper, cotton straw biochar as the material, the biological and physicalproperties of biochar were studied. The adsorption properties of biochar on mercury andarsenic under different conditions also were studied. The thermodynamic process ofmercury adsorption by biochar was investigated by isothermal titration calorimetry (ITC). In combination with the special saline-alkali environment in Xinjiang and the high contentof heavy metals in tailings, bacteria with the ability of urea decomposition and tolerance toheavy metals were isolated. The ability of this bacterium to induce calcium carbonate andthe removal of mercury and arsenic by calcification were investigated. Finally, under theoptimum solidification conditions, biochar was added into the tailings to study the effect of biochar on the control of heavy metal pollution by MICP tailings. The main conclusions ofthis study are as follows:(1)Biochar has abundant pore structure, large surface area and negative charge. Salinity has some effects on biochar adsorption of mercury and arsenic. Biochar has highadsorption capacity of Hg2+ at pH 5 and the maximum adsorption capacity was 5.81 mg/g. The adsorption capacity of biochar of 10 mg/L Hg2+ was up to 4.26 mg/g at 5 ‰ saltconcentration. Solution pH influenced the morphology of As solution, adsorption capacityof biochar on As3+ was up to a maximum of 2.76 mg/g at pH 7. The effect of salinity on theremoval of arsenic by biochar was not obvious, maximum adsorption capacity was 2.60mg/g at 5 mg/L As3+. (2) A thermodynamic study on the adsorption of mercury by biochar using a newSIITC method. At the initial stage it was surface adsorption process, that can be simulatedwith linear model. After that was surface adsorption and particle diffusion process and thenwas particle diffusion process which can be simulated with linear model. Proton adsorptionexperiment proved the particle diffusion process. The whole adsorption process of Hg2+ was available of index equation fitting. (3) A strain Staphylococcus succinus with high urea decomposition ability and acertain tolerance to heavy metals was isolated. Using SIITC technology to study thetolerance of S. succinus to heavy metals, and SIITC is a microbial detection method whichcan be applied to other heavy metals contaminated by other factors. (4) S. succinus bacteria had the ability of calcification and could produce CalciumCarbonate Granules. In the process of MICP had good removal effect of Hg2+, As3+ andremoval rate were more than 90%. The addition of humic acid had no obvious effect on thecalcification process. (5)Through different screening conditions, final optimum solidification conditionswere OD600=0.7, 4% urea and 40 mM calcium chloride. 2.5% biochar was the optimaldosage. The irregular calcium carbonate crystals were formed after solidification of thetailings. The calcium carbonate crystals connected the tailings particles and biochar particles together, thereby enhancing the curing effect. The content of heavy metals in theleachate of the samples decreased with the increase of the amount of biochar, theexchangeable state of the heavy metals decreased, and the binding state of the carbonatebound and Fe-Mn oxides bound were increased. The process of freezing and thawingreduced the curing effect of tailings, and the compressive strength decreased with theincrease of freeze-thaw cycles
古尔班通古特沙漠土壤种子库时空特征及其对积雪覆盖改变的响应
No full text古尔班通古特沙漠是我国最大的固定和半固定沙漠，自 80 年代以来沙漠油气资源开发、公路建设、过度放牧等对沙漠植被产生严重的干扰，使维持沙漠地表稳定的基本条件正趋于丧失，威胁着荒漠生态系统的稳定性。土壤种子库是植被更新和恢复的重要前提，深入了解该沙漠土壤种子库特征及其与地上植被的关系，对于指导受损植被的恢复实践具有重要意义。鉴于此，本文以古尔班通古特沙漠为研究区域，分析了沙丘 7 个地貌部位土壤种子库时空分布特征，解析了土壤种子库及其与地上植物关系，阐明了土壤种子库空间分布格局的尺度效应，探讨了积雪变化对土壤种子库种子萌发及种子活力的影响。主要研究结果如下：（1）沙丘冬季、春季和秋季沙丘土壤种子库密度在整体上（0-10 cm）分别为478.87 seeds/m2、97.87 seeds/m2 和 177.86 seeds/m2，呈显著差异；土壤种子库物种丰富度分别为 17、11 和 12 种，生活型均以短命植物占绝对优势；土壤种子库密度、物种丰富度、Shannon-Wiener 指数、Simpson 指数和 Pielou 均匀度指数均表现为从冬季土壤种子库到秋季土壤种子库呈“V”型变化即春季土壤种子库各数量特征均为最低。（2）沙丘0-10 cm土壤层次3种土壤种子库的密度、物种丰富度、Shannon-Wiener指数、Simpson 指数和 Pielou 均匀度指数受坡位影响显著，其中迎风坡底部、背风坡3 个坡位的冬季种子库和春季种子库间有显著差异。0-2 cm 土壤层次 3 种土壤种子库各数量指标也受坡位影响显著，其中在迎风坡坡底、背风坡上部和下部多表现出冬季土壤种子库显著高于春季，但个别坡位存在秋季显著高于春季。（3）沙丘植物种以菊科为主，生活型多为短命植物；迎风坡植物密度显著少于背风坡，且随季节变化两坡向植物密度变化均呈“V”型，共有种以背风坡相对较多。α 多样性指数在迎风坡及背风坡均为坡上部最大，坡底最小且有显著差异；从早春到秋季各坡位 α 多样性指数呈减少和“V”型两种变化趋势。β 多样性指数变化表明随坡位升高，迎风坡和背风坡物种替代性指数降低，相似性指数增加，两者在背风坡均表现为显著变化；从早春到秋季两坡向上物种替代指数增加，相似性指数降低，但替代性指数均无显著差异，沙丘坡向和坡位对草本植物α多样性和β多样性时空格局均产生显著影响。（4）沙丘 7 个坡位 0-10 cm 冬季、春季和秋季土壤种子库相似性关系中冬季土壤种子库相似性系数均较春季和秋季为高，但同一种子库在 7 个坡位间相似性系数无显著差异；7 个坡位 0-2 cm、2-5 cm 和 5-10 cm 土壤层次 3 种土壤种子库相似性均以0-2 cm 为最高。土壤种子库与地上植物组成的物种存在关系中以“只有地上植物但无土壤种子库”的物种数量始终为最高。土壤种子库及地上植物物种生活型均以短命植物为主。（5）相比与土壤种子库种子密度和物种丰富度，Shannon-Wiener 指数、Simpson指数和 Pielou 均匀度指数具有更为明显的空间尺度效应；Pielou 均匀度指数随取样面积增加呈线性负相关，最小取样面积不能确定；其余 4 个土壤种子库数量特征均随取样尺度增加呈现单峰分布特征，建议测定种子密度的取样尺度为 0.5 m×0.5 m，物种丰富度指数、Shannon-Wiener 指数和 Simpon 指数为 2 m×2 m。（6）积雪处理对不同植物种子萌发率影响为：抑制萌发、促进萌发、对种子萌发的影响不定；不同积雪处理还显著影响部分植物种子萌发。在积雪处理对种子萌发有促进作用的植物种中，短命植物最多，多年生植物最少；有抑制作用的植物种则主要以短命植物和多年生植物为主。未萌发种子复水萌发率表现出 4 种变化趋势：随积雪厚度增加，复萌萌发率呈单调增加或单调降低的变化趋势；呈“V”型或倒“V”型变化趋势，拐点均出现在自然降雪处理下。积雪处理导致 36.54%的植物所有未萌发种子失去活力。积雪处理对未萌发种子潜在活力均表现两种影响：正效应和负效应。尤其是在积雪处理对种子萌发有抑制作用的植物种中，去雪、自然降雪和加雪处理对短命植物种子萌发负效应高于一年生长营养期植物、多年生草本和灌木