青海湖湖水性质、颗粒物沉积通量季节和年际变化——来自沉积物捕获器的研究

本文通过在青海湖南盆沉积中心试验性放置的Mark 8-13型时间序列沉积物捕获器所收集到的为期15个月的自然沉降颗粒物,分析了颗粒物沉积通量和物质组成,结合温盐传感器（CTD）所记录湖水参数数据的分析,讨论了青海湖上部10 m左右湖水中所发生沉积作用的季节与年际变化特征及其与环境参数的相互关系。结果表明,采集期间所沉降的总颗粒物具有显著季节和年际变化特征,其平均年沉降通量为112 g·m^-2·yr^-1,其组成主要是自生碳酸盐（高Mg方解石、文石）、生物壳体（介形虫、硅藻等）等内生作用形成的物质,以及少量的碎屑矿物。与实时监测的湖水参数比较表明,具有显著季节和年际变化的青海湖内生物质通量变化主要受控于夏季温度的变化。其沉积机制为：湖水温度的升高,有利于高Mg方解石和文石等自生矿物从碳酸盐过饱和的碱性湖水中结晶沉淀（盐度降低）,也有利于藻类和介形虫等微体生物大量繁殖,表现为温度偏高的2010年比2011年具有较低的湖水盐度和高得多的沉积通量。因此,青海湖自生碳酸盐沉淀通量可以用来反映湖水盐度和/或温度的变化,尽管这些内生作用形成的物质可能只约占到湖底沉积物的5%~20%。为更全面地了解青海湖现代沉积过程,有必要在更多点位、不同的深度进行长期放置捕获器和实时监测湖水参数变化。     

光照与东海近海中肋骨条藻(Skeletonema costatum)赤潮发生季节的关系

利用船基现场培养实验和模型计算的方法,研究了光照与东海近海春夏季均能发生中肋骨条藻赤潮的关系.结果表明,中肋骨条藻生长的最适光照强度(I_opt)随水温(t)的增加呈“慢升快降”的不对称“倒V”形变化特征,在25℃左右I_opt最大,为121.6 Ｗ·m^-R, I_opt-t 曲线符合Blanchard方程; 由东海海表水温计算的中肋骨条藻I_opt的季节变化特征与东海海面光照强度、海水透明度的季节变化基本同步(R^R=0.907±0.115, p<0.001),且滞后于海面光照强度2个月左右,这使春夏季海水中光照最适宜生长的水层均为全年最厚(6m左右).可见,中肋骨条藻对光照的适应性很强,海区海水光照的适宜性是春夏季均能形成大规模中肋骨条藻赤潮的重要原因之一.     

Cyclo-stationary maximum cross-covariance analysis for exogenously forced environmental systems

The response of an ecological system to external forcings shows marked seasonality and complex time delays. In order to take seasonality into account, the assumption of stationarity inherent in most statistical models for time series is replaced here by more flexible cyclo-stationarity. To describe the dominant modes of the cross-covariance structure of the system and the forcing, temporal (orthonormal) patterns are derived. They are estimated by a singular value decomposition of the cyclo-stationary sample cross-covariance matrix. These patterns allow to formulate a prediction scheme for the system once the forcing is known. The method has comparatively little tendency for multi-collinearity, so that it is well applicable also for multivariate settings and shorter data records. The method is illustrated for an aquatic ecosystem with distinct phases of a biological succession.     

中国区域反应性气体排放源清单

反应性气体是形成气溶胶及酸雨、光化学烟雾等环境问题的重要前体物,采用政府部门公布的基础数据(包括社会－经济数据、化石燃料和生物质燃料消耗、废物处理数据等,绝大部分为县级水平)及一些较新的、中国特有的排放因子,计算了中国大陆2007年高时空分辨率的关键反应性气体SO2、NOx、CO、NH3、VOCs的排放源清单.计算出的全国和各地区的排放量使用了0.5°×0.5°的网格来显示,结果表明,各反应性气体的估算年排放量分别为:SO2 3158.4万t,主要是燃煤所致;NOx、CO分别为2492.6,15785.2万t,均主要来源于燃煤和生物质燃烧;NH3 1601.7万t,主要源于动物排放和农田化肥的使用;VOCs 3709.8万t,主要源于溶剂挥发、废物处理、交通源等.本研究计算的排放结果比以前的清单稍高,主要是由于部分排放量以前被低估了;东部地区的排放量比西部高.反应性气体的排放具有较强的季节性,主要是由于自然因素及居民采暖、农业秸秆的露天焚烧的季节性等所致.     

青海湖硅藻组合及其季节变化——来自沉积物捕获器的初步研究

通过对青海湖捕获器中2010年7月至2011年10月份沉积物样品与青海湖湖岸7个地点表层样品的分析,获得青海湖现代硅藻组合及季节变化特征。捕获器沉积物样品中共鉴定出硅藻2纲32属56种,主要为咸水种与微咸水种。其中,优势种为Berkeleya rutilans、Cocconeis placentula var. euglypta、Cyclotella choctawhatcheeana和Nitzschia inconspicua,此四种占总数的82%以上。硅藻组合变化具显著的季节性差异,冬季主要以浮游种Cyclotella choctawhatcheeana占优势;非冰封期则以附生种Berkeleya rutilans、Nitzschia inconspicua与Cocconeis placentula var. euglypta占优势。青海湖湖水具有高碱度,硅藻的保存率不高,其保存率具有夏季高、冬季低的季节性变化,但这不是造成硅藻组合显著季节性变化的主要原因,其季节性变化主要取决于水生植物的生长与湖区冰情。     

青岛市国际旅游的季节性研究——基于不同的视角

以青岛市国际旅游统计数据为基础,利用X-12- ARIMA和TRAMO/SEATS方法,从国际旅游人数和人均旅游花费两个视角对其季节性问题进行深入分析.研究表明,不同视角下的季节性模式存在显著差异,并进而提出缓解季节性问题的相关建议.     

Complexity,continuity and change: livelihood resilience in the Darfur region of Sudan

Darfur farming and pastoralist livelihoods are both adaptations to the environmental variability that characterises the region. This article describes this adaptation and the longer‐term transformation of these specialised livelihoods from the perspective of local communities. Over several decades farmers and herders have experienced a continuous stream of climate, conflict and other shocks, which, combined with wider processes of change, have transformed livelihoods and undermined livelihood institutions. Their well‐rehearsed specialist strategies are now combined with new strategies to cope. These responses help people get by in the short term but risk antagonising not only their specialist strategies but also those of others. A combination of factors has undermined the former integration between farming and pastoralism and their livelihood institutions. Efforts to build resilience in similar contexts must take a long‐term view of livelihood adaptation as a specialisation, and consider the implications of new strategies for the continuity and integration of livelihood specialisations.     

WATER QUALITY IN AGRICULTURAL WATERSHEDS: IMPACT OF RIPARIAN VEGETATION DURING BASE FLOW1

ABSTRACT: Water quality was monitored for 17 months during base flow periods in six agricultural watersheds to evaluate the impact of riparian vegetation on suspended solids and nutrient concentrations. In areas without riparian vegetation, both instream algal production and seasonal low flows appeared to be major determinants of suspended solids, turbidity, and phosphorus concentrations. Peak levels of all parameters were reached during the summer when flows were reduced and benthic algal production was high. Similar summer peaks were reached in streams receiving major point inputs but peaks occurred downstream from the input. Instream organic production was less important in regulating water quality in areas with riparian vegetation and permanent flows. Concentrations of suspended solids remained relatively constant, while phosphorus and turbidity increased in association with leaf fall in autumn. Intermittent flow conditions in summer increased the importance of instream organic production in controlling water quality, even when riparian vegetation was present. Efforts to improve water quality in agricultural watersheds during base flow should emphasize maintenance of riparian vegetation and stable flow conditions.     

The Characteristics of Tropospheric Ozone Seasonality Observed from Ozone Soundings at Pohang, Korea

This paper presents the first analysis of vertical ozone sounding measurements over Pohang, Korea. The main focus is to analyze the seasonal variation of vertical ozone profiles and determine the mechanisms controlling ozone seasonality. The maxima ozone at the surface and in the free troposphere are observed in May and June, respectively. In comparison with the ozone seasonality at Oki (near sea level) and Happo (altitude of 1840 m) in Japan, which are located at the same latitude as of Pohang, we have found that the time of the ozone maximum at the Japanese sites is always a month earlier than at Pohang. Analysis of the wind flow at the surface shows that the wind shifts from westerly to southerly in May over Japan, but in June over Pohang. However, this wind shift above boundary layer occurs a month later. This wind shift results in significantly smaller amounts of ozone because the southerly wind brings clean wet tropical air. It has been suggested that the spring ozone maximum in the lower troposphere is due to polluted air transported from China. However, an enhanced ozone amount over the free troposphere in June appears to have a different origin. A tongue-like structure in the time-height cross-section of ozone concentrations, which starts from the stratosphere and extends to the middle troposphere, suggests that the ozone enhancement occurs due to a gradual migration of ozone from the stratosphere. The high frequency of dry air with elevated ozone concentrations in the upper troposphere in June suggests that the air is transported from the stratosphere. HYSPLIT trajectory analysis supports the hypothesis that enhanced ozone in the free troposphere is not likely due to transport from sources of anthropogenic activity.     

Coping strategies and risk manageability: using participatory geographical information systems to represent local knowledge

The accumulated knowledge and perceptions of communities 'at risk' are key elements in managing disaster risk at the local level. This paper demonstrates that local knowledge of flood hazards can be structured systematically into geographic information system (GIS) outputs. When combined with forecasting models and risk scenarios, they strengthen the legitimacy of local knowledge of at-risk populations. This is essential for effective disaster risk reduction practices by external actors, local non-governmental organisations (NGOs) and municipal authorities. The research focused on understanding coping strategies and 'manageability' of flood hazards as defined by communities. 'Manageability' is how people experience flooding in relation to their household capacity and the coping mechanisms available. The research in the Philippines highlights the significance of localised factors, including socioeconomic resources, livelihoods, seasonality and periodicity, for understanding manageability. The manageability concept improves practice at the municipal level by legitimising local coping strategies, providing better indicators, and developing understanding of flooding as a recurrent threat.