Exchange of Short-Chain Oxygenated Volatile Organic Compounds (VOCs) between Plants and the Atmosphere: A Compilation of Field and Laboratory Studies     

J. Kesselmeier 《Journal of Atmospheric Chemistry》2001,39(3):219-233

Field and laboratory investigations of the exchange of the short-chain organic acids – formic acid and acetic acid – as well as their homologous aldehydes are discussed. Both acids are substantially released from several plant species. Emission measurements under field conditions are compiled to give an overview of three years of measurements. Emission rates from several tree species were found in the range between zero and 60 nmoles m^–2 min^–1 for acetic acid and between zero and 90 nmoles m^–2 min^–1 for formic acid though also a deposition has been observed to orange trees. Investigations under laboratory conditions showed an order of magnitude lower emission rates with significant differences under light and dark conditions, and a deposition was observed under certain conditions. Hence, low emission rates or even a bi-directional exchange, emission as well as deposition have to be taken into account. Further differences between field and laboratory studies are discussed considering age of trees, stress effects and a potential production of acids by photochemical conversion of precursors inside enclosures during sampling. Field data on the exchange of form- and acetaldehyde show a complex behavior. We found emission as well as uptake. The bi-directional exchange is significantly triggered by the ambient mixing ratios of both aldehyde species and exhibits a compensation point. Further studies are needed for generalization of the exchange of these and potentially also for other compounds.  相似文献   

原子吸收光谱法测定氰化液中的铅     

曹会兰  杨兴武 《岩矿测试》2001,20(4):309-311

通过对比实验，选用柠檬酸钠做络合剂，实现了在碱性介质中用原子吸收光谱测定铅的方法。应用该方法测定实际样品的结果与其他方法相符，对于2.19mg/L Pb浓度的试液10次测定的RSD为1.8%。  相似文献   

鹿井碎裂蚀变花岗岩型铀矿床溶浸评价研究     

李建红  罗毅  王明太  孙志富  周青生 《铀矿地质》2001,17(3):168-173,149

本文从矿床的地质评价入手，对矿体形态、产状、规模，矿石的物质成分，矿石结构构造，铀的存在形式，矿床水文地质、工程地质等诸多方面进行了矿床溶浸天然地质条件研究；通过对低品位、大块度的铀矿石进行柱浸工艺试验，获得了一系列溶浸工艺参数；归纳分析出高昔、牛尾岭矿床的矿石灰第2类有利溶浸类型；提出常规采治法、原地破碎浸出和堆浸相结合的采治方案。  相似文献   

塔河油田下奥陶统溶蚀段的测井响应   总被引：1，自引：0，他引：1       下载免费PDF全文

宋杉林  崔民  傅恒 《沉积与特提斯地质》2001,21(3):76-81

塔河油田位于塔里木盆地，为该盆地油气中储量最大，产量最高的油田。下奥隐统是塔河油田最重要的储集层段，而下奥陶统中溶蚀成因的孔洞又是该层段最主要的储集空间。通过对该溶蚀段的研究，笔者认为该溶蚀段具有可以识别的测井响应，其密度呈指状急剧降低，是溶蚀段最明显的特征，并以此与中上奥陶统的瘤状灰岩形成明显区别。  相似文献   

Li,K／Cl,SO4—H2O体系相平衡的热力学   总被引：1，自引：1，他引：1       下载免费PDF全文

宋彭生  姚燕 《盐湖研究》2001,9(4):8-14

介绍了根据自己研究测定的Li,K/Cl,SO4-H2O体系25℃的渗透系数等热力学性质获得的Pitzer混合参数，并用自己能量小化方法计算25℃Li,K/Cl,SO4-H2O体系的相图，结合测定得到的该体系50℃75℃的相图和复盐LiSO4转变温度的研究，整个体系相平衡和热力学的研究结果可用于盐湖卤水锂盐的分离提取。  相似文献   

两种覆盖方式下的土壤溶液盐分含量变化   总被引：12，自引：0，他引：12  

黄强  殷志刚  田长彦  汪宏年  张建军  陈春英 《干旱区地理》2001,24(1):52-56

利用定期取表层土样测定其电导率和在不同深度埋设盐分传感器探头的方法，在作物生长季节内，监测了秸杆覆盖和地膜覆盖农田不同深度的土壤溶液含盐量变化。结果为：（1）土壤表层盐分含量和10cm深土壤溶液含盐量的变化规律为，未灌水期间迅速增加；灌水时急剧降低。秸杆覆盖和覆膜可明显抑制盐分的累积，使整个生育期内土壤盐分含量波动幅度变小。其中覆膜处理抑制土壤盐分累积的作用最大。（2）30cm深土壤溶液含盐量的变化为灌水降低，未灌水时升高。秸杆覆盖处理在灌头水后含盐量虽有波动，但总体上呈下降趋势；覆膜处理在灌头水后一直处于很低的含盐水平。（3）60cm深土壤溶液含盐量变化幅度小于其上土层。秸杆覆盖增强了灌水对60cm土壤溶液含盐量的降低作用，并抑制了后期土壤溶液含盐量增加。覆膜减少了灌水对60cm深土壤溶液含盐量的降低幅度，也抑制了未灌水期间含盐量的增加。  相似文献   

硼溶液蒸发过程中硼的挥发及硼同位素分馏          下载免费PDF全文

肖应凯 Vocke  RD 《盐湖研究》1997,5(1):28-38

用蒸发实验研究了浓度为10-6级的硼在水和稀HCl溶液蒸发时的挥发度、同位素分馏和甘露醇的影响。结果表明，在溶液中有等摩尔的甘露醇和Cs都存在的条件下，硼才能在蒸发时和蒸干后保持定量回收；硼在不加入甘露醇或Cs的稀HCl溶液中蒸发时也能定量回收，但是不能蒸干；若要蒸干．必须加入等摩尔的甘露醇，才能保持硼的定量回收。蒸发液和残留液的同位素测定表明，11B仇先从近中性和酸性溶液的蒸发中贫化。此结果对于硼需要预富集的过程是非常重要的。  相似文献   

中国外商直接投资的地域结构研究   总被引：19，自引：2，他引：19  

焦华富 《地理研究》1997,16(3):32-38

改革开放以来,我国引进外资工作取得了较大进展。然而,外资地域分布的不平衡,成为导致区域经济发展水平差距拉大的一个重要原因。如何改善外资地域分布结构,成为各界关注的焦点之一。文中采用定量和定性相结合的方法,研究了中国外资地球分布的现状及特点,分析了外资地域分布的动态变化趋势,并在此基础上提出若干改善外资地域分布结构的举措。  相似文献   

Measurement of gaseous HNO3 over the Atlantic Ocean     

T. H. Papenbrock  F. Stuhl  K. P. Müller  J. Rudolph 《Journal of Atmospheric Chemistry》1992,15(3-4):369-379

A latitudinal profile (30° W, from 30° N to 30° S) of mixing ratios of nitric acid and particulate nitrate was determined on the Atlantic Ocean during the Polarstern cruise ANT VII/1 from Bremerhaven, Germany, to Rio Grande, Brazil. The detection of HNO₃ was performed simultaneously by laser-photolysis fragment-fluorescence (LPFF) and by nylon filter packs. The detection limit was about 30 pptv for a signal accumulation time of 1 h for LPFF and about 5 pptv for the filters at a collection time of 4 h. In general, the mixing ratios of HNO₃ in the Northern Hemisphere were found to be significantly higher than those in the Southern Hemisphere. The Atlantic background concentrations frequently varied between 80 pptv and the detection limit. Larger deviations from this trend were found for the more northern latitudes and for episodes like crossings of exhaust plumes from ships or from continental pollutions sources.  相似文献   

日本海-鄂霍次克海下俯冲带的应力状态及其深部形变   总被引：8，自引：1，他引：8       下载免费PDF全文

臧绍先  吴忠良 《地球物理学报》1992,35(5):560-573

通过地震分布及地震机制解所反映的日本海-鄂霍次克海俯冲带的形态及应力状态,研究了俯冲带深部形变及650km间断面的穿透问题.日本海Benioff带较直,连续性较好;鄂霍次克海Benioff带弯度稍大,220-320km深度之间地震很少.两俯冲带在浅部及深部地震密集,100-200km深度之间有双地震层.应力状态随深度变化,200km深度以下P,T轴方向相对集中,P轴接近俯冲方向,在约100-200km深度附近,P,T轴均接近俯冲方向.观测和理论地震图拟合分析表明,地震断层面走向接近俯冲带走向,断裂的结果使俯冲带在深部倾角变小.  相似文献