树木年轮分析在环境监测中的应用进展

阐述树木年轮在环境中应用的基本原理，综合分析树木年轮分析在环境监测中应用的发展历程和最新进展，通过研究实例扼要综述树木年轮在大气痕量金属沉降的监测、水体和土壤重金属沉降的监测、有机污染物的推断和人工合成放射性元素的调查研究中的重要领域，探讨树木年轮研究存在的不足、难以解决的问题及可能改进的途径。认为今后利用树木年轮研究环境变化的重要领域是树木逆境条件下生理特性的基础理论研究、污染元素时空分异规律的研究、污染元素进入树木体内动力学过程及其与环境相关性的研究，以及多学科交叉、与其他环境信息源记录的比较研究。     

新疆树木年轮研究特色

本对40多年来新疆树木年轮研究工作做了简要总结．发现有以下研究特色：1．在年轮水学方面开启了我国利用树木年轮重建河流径流量和河流径流深度场研究的先河；2．在年轮气候学方面，主要是利用树木年轮重建空间上大尺度的气候要素变化，开创我国沙漠地区树木年轮研究工作，利用树木年轮重建某地区单旬降水和山区降水日数，研究了雪与树木年轮的关系以及冰期与降水的关系，创立大样本、多年表、面控制的采轮布局策略等；3．在年轮与环境方面利用树木年轮做春小麦气候产量预报，建立了树木年轮与大气环流因子的关系等。     

树木稳定碳同位素比率的方位差异及其机理初步研究

测定了祁连山一棵千年圆柏不同方位上树木稳定碳同位素比率 (δ13 C值 )和光合作用色素 .结果显示 ,树木中 δ13 C值具有明显的方位差异 :北面的 δ13 C值相对较高 ,西面的 δ13 C值相对较低 .树叶中叶绿素含量、类胡萝卜素含量和类黄酮含量的方位变化趋势与δ13 C值类似 .分析表明 ,后者的方位变化是树木对局部环境的光辐射差异长期适应的结果 ,而树木中δ13 C值的方位差异可归咎于光同时引起光合作用和呼吸作用变化的缘故     

土壤中非传统稳定同位素研究进展

过去十几年来,非传统稳定同位素在地球表生环境中的应用得到广泛关注.土壤处于地球表层特殊的空间位置,与其他各圈层不间断地进行物质和能量交换.结合已有的相关研究,本文对非传统稳定同位素在土壤中的分馏行为和重要应用潜力进行了论述,重点以Mg,Fe,Si和Hg等元素同位素为代表,从风化和成土过程、营养元素在植物-土壤之间的循环及重金属污染三个方向阐述土壤基础研究存在的重要科学问题.简要总结了近几年的研究现状,指出目前土壤中非传统稳定同位素值得深入研究的方向.非传统稳定同位素在土壤研究中的应用,是将稳定同位素地球化学与土壤学、环境生态学等学科交叉与融合的典型范例,是土壤学科发展的一个重要趋势.     

自然生长树木气孔导度对CO2浓度升高的响应

研究了近２４０ａ自然生长树木气孔导度对ＣＯ２浓度变化的长期响应,在测定树轮稳定碳同位素组成的基础上,计算了大气ＣＯ２浓度和叶片内部ＣＯ２浓度差（ｃａ－ｃｉ）和树木年轮面积与ｃａ－ｃｉ的比例（以Ｇ表示）。ｃａ－ｃｉ和Ｇ均随ＣＯ２浓度的升高而有所增加,在１９９０年之前,ｃａ－ｃｉ的升高主要与植物同化能力的提高有关,１９００年之后,气孔对大气ＣＯ２的导通能力起主要作用。而Ｇ的升高可能与ＣＯ２浓度升高改变     

山东塔山黑松树轮稳定碳同位素与气候要素的响应

在山东塔山东坡采集黑松(Pinus thunbergii Parl)树芯样本,建立树轮稳定碳同位素年表,发现在数十年尺度上与工业革命以来大气稳定碳同位素比率降低的事实相吻合,但1976年之后树轮稳定碳同位素比率(δ13C)有逐渐上升的趋势,其原因可能是大气中CO2的积累效应导致了大气与海洋之间CO2交换的不稳定性.通过对样本δ13C序列校正提取高频序列后与气象站气象资料进行相关分析,发现树轮δ13C序列与温度呈正相关,与降水量和日照时数呈负相关,温度和降水以及日照时数对树轮δ13C的影响均存在一定的滞后效应,该地区树木生长的限制性气候因子比较复杂,可能受到多种气候因子的共同影响,在气候重建研究中应当慎重选择.     

稳定碳、氮同位素在生态系统研究中的应用

在简要介绍了稳定同位素测定方法之后，对稳定碳、氮同位素在生态系统领域中关于系统的碳源、能量流动、营养结构、污染物的生物放大作用及系统稳定性变化的应用研究作了较为系统的论述，并对稳定碳、氮同位素在赤潮研究、环境污染治理、生态动力学建模及有机分子化合物系列示踪技术等方面的应用提出展望。     

埋藏古木树轮碳、氢、氧同位素研究与古气候重建

树轮作为自然档案的一种,其同位素研究对探讨全球气候和环境变化具有重要的意义.文章系统地介绍了树轮碳、氢、氧同位素的分馏原理, 研究方法以及纤维素的提取等.研究表明,树轮同位素作为环境变化的示踪剂,是古环境再造和了解现代环境气候变化的一个强有力工具.尤其是在过去全球变化(PAGES)研究中,埋藏古木纤维素中的碳、氢、氧同位素分析已成为环境演化研究的主要量化手段.另外,对于中国这样典型的季风气候国家,开展树轮稳定同位素随季节性变化的研究具有重要的意义. 我国在树轮研究方面起步较晚,研究方法和研究内容上也比较简单,还存在不小差距,既要进一步积累基础资料,又要做区域对比,加强与相关学科的交叉研究.     

稳定性碳同位素在C4植物水分利用效率中的研究进展

对稳定性碳同位素的原理作了介绍,进而分析了稳定性同位素分辨率与水分利用效率的关系及近几十年稳定性碳同位素技术在C4植物水分利用效率中的应用,把稳定性碳同位素分辨率等与C4植物水分利用效率之间进行量化分析,同时也分析了稳定性碳同位素分辨率与其他性状指标之间的关系.最后就稳定性碳同位素在C4植物以后研究中的应用进行扩展分析,以期为稳定性碳同位素在C4植物中的研究提供理论依据.     

珠江三角洲陆地生态系统环境质量演变与健康研究：为认识快速城市化、工业化过程中的环境质量演变提供数据资料

近期，华南植物园环境退化与生态恢复研究领域温达志、旷远文、孙芳芳、李炯等科研人员，针对珠江三角洲快速城市化进程中酸沉降及重金属污染对森林群落和生态环境带来严重威胁等问题，以城市工业污染区和远郊相对清洁区的代表性森林生态系统为对象，借助树木年代学与年轮化学、根区土壤化学及稳定同位素化学等研究手段，探讨污染指示元素的年代变化、     

再建气候环境演化历史的碳同位素技术

稳定碳同位素是再建气候环境变化历史最重要手段。简要回顾了碳同位素分馏的主要影响因素。介绍了碳同位素变化与生态环境变迁的可能关系 ;重点探讨了利用碳同位素再建古大气CO2 的原理和方法     

Climatic significance of stable carbon isotope in tree rings of Abies spectabibis in southeastern Tibet

The annually cross-dated stable carbon isotope of tree-ring a-cellulose of Abies spectabibis collected from the southeastern Tibetan Plateau is used to examine its rela-tionship with climatic parameters. The residual D13C series in treerings is constructed after removing the effects of age trend and rising CO2. We found a close relationship between D13C in tree rings and the relative humidity of September—November of the previous year measured at the nearby Ny-ingchi Meteorological Station, albeit a strong 搇agged effect? Thus we developed a transfer function to reconstruct the autumn relative humidity for the Nyingchi region, which explained 37.9% of the total variance (p < 0.001). Our results suggest a high frequency and moderate amplitude variance of the relative humidity before 1800, and the variance re-versed afterwards.     

Response of tree-ring width to rainfall gradient along the Tianshan Mountains of northwestern China

By comparing the long-term tree-ring growths at various geographic scales, we can make clear the effects of environmental variations on tree growth, and get an understanding of the responses of forest ecosystems to the possible changes in global and regional climate. Radial tree-ring growth of Picea schrenkiana and its relationship to air temperature and precipitation were investigated across longi- tude transects on the north slopes of the Tianshan Mountains in northwestern China. Tree-ring samples were collected and residual chronologies were developed for three different regions along a gradient of decreasing precipitation from west to east. Response-function analysis was conducted to quantify the relationships between tree-ring chronologies and climate variables, such as monthly mean temperature and monthly precipitation from 1961 to 1998, using the PRECON software program. The statistical characteristics of the chronologies showed that the three chronologies constructed in this study con- tained significant environmental signals and were well suitable to reveal the impacts of climatic change on tree growth and forest productivity. Annual ring-width variations were similar among the three sites, but the variability was greatest in the east. This research showed that the growth trends of Picea schrenkiana in the Tianshan Mountains have not followed a uniform pattern. Response-function analy- sis indicated that there were significant correlations between tree growth and climatic factors in all the three regions, among which precipitation was the principal. With decreasing precipitation, the response of tree-ring widths to increasing temperature changed from a positive to a negative correlation. As for precipitation, the positive relationship to tree-ring width always dominates. It could be expected that with increased temperature and decreased precipitation, the importance of precipitation to tree growth would increase, and the response of tree growth to environmental changes would also increase. This study emphasizes the importance of regional-scale investigations into the biosphere-climate interac- tions. The results of this research indicated a substantial increment of tree-ring radial growth as a re- sult of warmer and wetter climate in the eastern regions. However, climate change will have less effect on forest growth and primary production in the western regions.     

Effect of acetazolamide on stable carbon isotope fractionation in <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> and <Emphasis Type="Italic">Chlorella vulgaris</Emphasis>

The effect of extracellular carbonic anhydrase (CAex) on stable carbon isotope fractionation in algae is still unclear. The stable carbon isotope composition and algal growth in the presence and absence of the membrane-impermeable CA inhibitor acetazolamide were compared in Chlamydomonas reinhardtii and Chlorella vulgaris. The CAex of both algal species contributed about 9‰ of the stable carbon isotope fractionation and exhibited a dosage effect. Therefore, evidence in vivo that CAex leads to a larger carbon isotope fractionation of algae is presented.     

全球变化研究中的同位素地球化学

全球变化研究是90年代以来最为引人注目和关切的环境科学问题之一。全球环境变化的信息储存于树轮、湖泊、冰芯、黄土、地下水和海洋沉积物等载体中,随着稳定同位素技术的发展,同位素示踪剂指示环境变化的信息,成为了解古环境再造和现代环境信息变化的一个强有力的工具。     

Isotopic evolution of the terminal Neoproterozoic and early Cambrian carbon cycle on the northern Yangtze Platform, South China

Profound geotectonic, climatic and biological changes occur during the terminal Neoproterozoic and its transition into the early Cambrian. These are reflected in temporal variations of the chemical and isotopic composition of seawater. We are studying a sequence of sedimentary rocks at the Shatan section, northern Yangtze Platform, Sichuan Province of China. This succession comprises, in ascending stratigraphic order, predominantly calcareous sediments of the Sinian upper Dengying Formation and black shales of the lower Cambrian Guojiaba Formation (time equivalent of Niutitang Fm.). Paleoenvironmental setting represents shallow-water shelf deposits. The objective of our study is to provide temporal records for the isotopic compositions of organic and carbonate carbon throughout this time interval. Organic carbon isotope values display a range between -35.8‰ and -30.1‰ with clear stratigraphic variations. Carbonate carbon isotope data vary between -3.5‰ and +0.5‰. These secular variations are interpreted to reflect perturbations of the global carbon cycle, specifically changes in the fractional burial of organic carbon. However, local conditions have further affected the isotopic signals.     

胡杨径向生长与气候环境响应分析

 胡杨作为内陆干旱荒漠地区树龄较长的阔叶树种,是开展过去气候环境变化研究的宝贵材料.为了探讨胡杨树轮生长指标与气候环境之间的相关关系,本文在综述胡杨树种概况和生长区域气候环境特征的基础上,以新疆艾比湖流域胡杨为研究材料,利用树木年轮气候学分析方法,建立了艾比湖地区181年来的胡杨宽度年表.对宽度年表与精河、蔡家湖气象站的温度、降水序列进行了相关分析,结果表明,树轮宽度指标与冬半年降水呈正相关关系,相关系数最大为0.408,两个气象站中,精河站与年表相关系数高于蔡家湖站.通过与其他学者在该地区的研究成果对比分析,发现艾比湖胡杨树轮宽度指数高低时段与艾比湖湖面变化有很好的一致性,这与艾比湖地区地下水和湖面变化有密切关系,与胡杨生长受地下水变化影响的研究结论一致.