Studies of Oxidant Production at the Weybourne Atmospheric Observatory in Summer and Winter Conditions

Detailed studies have been made of the behaviour of gases and radicals involved in the production of oxidants at the Weybourne Atmospheric Observatory in both summertime and wintertime conditions. In June 1995 the range of meteorological conditions experienced varied such that ozone destruction was observed in clean northerly air flows reaching Weybourne down the North Sea from the Arctic, and ozone production was observed in varying degrees in air with different loadings of nitrogen oxides and other precursors. The transition point for ozone destruction to ozone production occurred at a nitric oxide concentration of the order of 50 pptv. Plumes of polluted air from various urban areas in the U.K. were experienced in the June campaign at Weybourne. Quantitative studies of ozone production in a plume from the Birmingham conurbation on 18 June 1995 showed that the measurement of ozone production agreed well with calculated production rates from the product of the nitric oxide and peroxy radical concentrations (r2=0.9). In wintertime conditions (October–November 1994) evidence was also found for oxidant production, defined as the sum of O3+NO2. At this time of year the peroxy radical concentrations (RO2) were much lower than observed in the summertime and the nitric oxide (NO) was much higher. There was still sufficient RO2 during the day, however, for a slow accumulation of oxidant. Confirmatory evidence for this comes from the diurnal co-variance of (O3+NO2) with PAN, an excellent tracer of tropospheric photochemistry. The same type of covariance occurs in summer between PAN and ozone. The results obtained in these series of measurements are pertinent to understanding the measures necessary to control production of regional photochemical air pollution, and to the production of ozone throughout the northern hemisphere in winter.     

The Tropospheric Gas-Phase Degradation of NH3 and Its Impact on the Formation of N2O and NOx

The gas-phase degradation of NH3 in the atmosphere still has many uncertainties. One of them is the possible isomerisation of NH2O to NHOH, as indicated by kinetic studies. Since NH2O is formed during the gas-phase oxidation of ammonia in the troposphere, this reaction can potentially influence the subsequent production of N2O and NOx. So far, the isomerisation has never been implemented into current chemical schemes describing the atmospheric gas-phase degradation of NH3 and its atmospheric relevance has never been assessed. The N2O yield from NH3 degradation is calculated to be in the range of 10–43 %. It depends on the NO2 and O3 concentrations, but is independent of the NH3 concentration. Compared with the results from recent literature, the N2O yield derived from the new mechanism is 20–80% lower, implying a smaller global N2O source strength of 0.4 Tg yr- 1. The production of NH2SO2 seems to be less important for the atmospheric degradation of NH3. NH3 oxidation is a sink for NOx at NOx mixing ratios of more than about 1 ppb and a source at lower NOx burdens.     

数值分析预报产品的拼合图制作系统

设计了数值分析预报产品的拼合图制作系统。该系统是在原地面传输网络上的格点资料绘图系统基础上制作的 ,对原系统进行了一系列改进。该系统属于MICAPS系统的二次开发内容之一     

地质工艺孔原地浸出采矿方法与技术

地质工艺孔原地浸出采矿法是一种利用地质工艺孔和化学试剂采矿的新型方法,通过生产试验,对工艺孔结构,布孔方式,施工技术,成井工艺等问题进行了讨论。     

贵州省主要粮食作物综合增产潜力

从大气作物土壤系统出发,建立了贵州省主要粮食和物综合生产潜力模式,提出了作物增产潜力指数的概念,分析了在现实条件下和未来条件下作物综合增产潜力的前景。     

从气候角度提高鲜奶产量的潜力

提出了总奶产量等于生理产奶量加营养产奶量和气候产奶量,即：Ｙ总＝Ｙ１＋Ｙ２＋Ｙ３,并重点讨论气候产奶量Ｙ３和营养产奶量Ｙ２。结果表明,各月平均水汽压,月平均气温,月平均最低气温和月蒸发量４个因子对气候产奶量影响较大,同时找出１９８８年的各月平均水汽压,１９９３年月平均气温,１９８９年月平均最低气温和１９８８年月蒸发量４个最佳气象条件的相似年,它们最利用于提高气候产奶量,其次找到了低产奶原因－产乳高     

垂直集成采样法在234Th—238U不平衡研究海洋新生产力中的应用

对基于梯形积分原理的集成采样法的可行性在理论上进行了阐述,并在厦门湾和南海北部的5个站位分别采集不同深度的水样和由这些水样按一定比例混合而成的集成水样进行了现场研究,结果表明两种采样方法经不可逆稳态清除模型得出的溶解态234Th的清除通量、颗粒态234Th的输出通量及溶解态、颗粒态234Th的停留时间基本一致,证实了垂直集成采样法的可行性与可靠性。这种新的采样方案为今后充分发挥234Th法的优势,在更大空间尺度上进行新生产力的研究提供了可靠的保证。     

现阶段我国乡村旅游产品的供需特征及开发

乡村旅游是中国“９８华夏城乡旅游”的发展主题之一。文章分析了我国乡村旅游产生的背景因素,总结了现阶段我国乡村旅游产品的供给和需求特征,并提出了乡村旅游开发中面临的主要问题及建议。     

黄土高原水土流失地区粮食生产潜力与发展途径

农业是国民经济的基础, 粮食是基础的基础。黄土高原地区是中华民族文化的发祥地,也是我国历史上早期农牧业生产区和政治中心,粮食是该区人民赖以生存的最基本产业。探索其发展规律, 分析其障碍因素, 寻求其发展潜力, 采取 “一靠政策, 二靠科技, 三靠投入, 四靠保护, 五靠工作”的战略措施, 对同类地区的粮食发展具有重要意义。     

Sonoran Desert productivity and the effect of trap size on litterfall estimates in dryland vegetation

We describe the temporal and spatial litterfall and test the accuracy of different litter collection devices in a Sonoran Desert community. Two low-lying PVC litter trap designs were tested and compared against a standard IBP trap. The test traps collected significantly more plant litter than the IBP traps, which failed to capture most of the litter of ephemerals and low shrubs. The largest differences between the traps appeared after the pulses of growth of ephemeral plants. Data collection for a period of almost 2 years showed an annual total litterfall of 3·43 Mg ha⁻¹for the test traps and 2·77 Mg ha⁻¹for the IBP traps. These values are well above the average for deserts and fit better into the lower range of tropical dry forests. The test PVC traps are inexpensive, economical in collecting and sorting effort, and less prone to vandalism. Also, they can be laid in higher numbers than IBP traps, thus providing a better representation of the highly heterogeneous desert environment.