载体对生物质油裂解镍基催化剂的性能影响

以改性处理的CaA分子筛、硅藻土和ZrO_2-CeO_2复合氧化物为载体,分别负载镍制备催化剂,并采用XRD、SEM、TPR、TG、FT-IR对催化剂的结构、形貌、表面酸中心种类、还原性能和积碳性能等进行了表征。结果表明,载体的种类影响催化剂性能,改性后的Ca A分子筛具有较大的比表面积和孔容,负载镍基催化剂表面具有较强的L酸和B酸中心,能与镍物种形成较强的相互作用,在生物质油催化裂解反应中表现出较好的活性,同时催化剂表面较强的酸中心也促进了积碳前驱物的形成;而Ni O/硅藻土催化剂和NiO/ZrO_2-CeO_2催化剂的酸中心强度相对较弱,影响了活性组分与载体的相互作用,活性组分在反应中烧结现象明显。     

两种底质对狐尾藻生长和生理指标的影响

在温室条件下,分别以土壤和沉积物作为底质,模拟研究狐尾藻（Myriophyllum spicatum）生长和生理指标的变化。结果表明：与营养水平相当的沉积物相比,以土壤作为底质的处理,其狐尾藻茎叶生物量降低了87．15％,根系生物量增加了226．54％,根系活力降低了46．46％,超氧化物歧化酶（SOD）和过氧化物酶（POD）活性分别增加了134．20％和119．91％。上覆水和间隙水中活性磷浓度分别增加了146．67％和1382．61％。以土壤为底质,增加该处理水体中磷浓度,抑制狐尾藻生长。     

The use of carbon and nitrogen isotope ratios to identify landfill leachate contamination: Green Island Landfill, Dunedin, New Zealand

A study was undertaken to determine whether the isotopic ratios of C and N could be used to uniquely identify municipal solid waste landfill leachate as a source of contamination in the Kaikorai Estuary, Dunedin, New Zealand. Leachate samples were taken from the adjacent Green Island Landfill (GILF), and surface water samples were collected over an 8-month period from the stream and estuary, upstream and downstream of the landfill. Samples were analysed for delta(13)C-dissolved inorganic carbon (DIC), delta(15)N-NO(3)(-), delta(15)N-NH(4)(+), and particulate organic matter (POM) delta(13)C and delta(15)N. Plant material collected along the Kaikorai Stream was analysed for POM delta(13)C and delta(15)N. Leachate was found to have a distinct isotopic signature characterised by a highly enriched delta(13)C-DIC (as much as 16.11+/-0.23 per thousand ) and highly enriched delta(15)N-NH(4)(+) (as much as 27.42+/-0.90 per thousand ). Evidence of leachate contamination was found in the isotopic signatures of downstream delta(13)C-DIC, delta(15)N-NH(4)(+), and delta(13)C and delta(15)N of plant material POM. Other potential sources of enriched delta(13)C-DIC and delta(15)N-NH(4)(+) present in the study area, such as estuarine waters and livestock effluent, were eliminated on the basis of their isotopic characteristics.     

ASSESSMENT OF SAMPLING ERROR ASSOCIATED WITH SOIL MOISTURE ESTIMATION DESIGNS1

A spectral formalism was developed and applied to quantify the sampling errors due to spatial and/or temporal gaps in soil moisture measurements. A design filter was developed to compute the sampling errors for discrete measurements in space and time. This filter has as its advantage a general form applicable to various types of sampling design. The lack of temporal measurements of the two‐dimensional soil moisture field made it difficult to compute the spectra directly from observed records. Therefore, the wave number frequency spectra of soil moisture data derived from stochastic models of rainfall and soil moisture were used. Parameters for both models were estimated using data from the Southern Great Plains Hydrology Experiment (SGP97) and the Oklahoma Mesonet. The estimated sampling error of the spatial average soil moisture measurement by airborne L‐band microwave remote sensing during the SGP97 hydrology experiment is estimated to be 2.4 percent. Under the same climate conditions and soil properties as the SGP97 experiment, equally spaced ground probe networks at intervals of 25 and 50 km are expected to have about 16 percent and 27 percent sampling error, respectively. Satellite designs with temporal gaps of two and three days are expected to have about 6 percent and 9 percent sampling errors, respectively.     

中国科学院生态系统网络观测与模拟重点实验室CERN综合研究中心研究成果与发展

介绍了中国生态系统研究网络(CERN)综合研究中心成立以来的发展历程和主要研究成果,以及未来研究方向及预期发展。取得的代表性研究成果主要有:CERN动态监测数据与生态系统空间信息数据管理和共享系统的开发、陆地生态系统碳和水热通量观测研究、陆地生态系统碳储量的时空格局特征研究、陆地生态系统多尺度模拟综合集成研究和青藏高原生态系统格局与全球变化相互作用关系研究等。未来的研究方向主要集中在陆地生态系统碳氮水循环及其耦合,区域碳汇功能动态,生态敏感区、脆弱区和过渡区对全球气候变化的响应与适应,生态监测、模拟与生态信息应用以及全球气候变化主要因子对生态系统关键过程的影响。未来除了履行CERN综合研究中心的基本职能外,争取在以上研究方向取得有国际影响的开拓性研究成果。     

Human disturbance and shifts in vertebrate community composition in a biodiversity hotspot

Understanding how human modification of the landscape shapes vertebrate community composition is vital to understanding the current status and future trajectory of wildlife. Using a participatory approach, we deployed the largest camera-trap network in Mesoamerica to date to investigate how anthropogenic disturbance shapes the occupancy and co-occurrence of terrestrial vertebrate species in a tropical biodiversity hotspot: the Osa Peninsula, Costa Rica. We estimated species richness in different categories of land protection with rarefaction analysis and estimated the expected occupancy with a joint species distribution model that included covariates for anthropogenic disturbance, land protection, habitat quality, and habitat availability. Areas with the most stringent land-use protections (e.g., Corcovado National Park, 24 species [95% CI 23–25]) harbored significantly more species than unprotected areas (20 species [19.7–20.3]), mainly due to a reduced presence of large-bodied species of conservation concern in unprotected areas (e.g., jaguar Panthera onca and white-lipped peccary Tayassu pecari). Small-bodied generalist species, such as opossums (Didelphidae) and armadillos (Dasypus novemcinctus), in contrast, were more common at disturbed sites, resulting in a significant difference in vertebrate community composition between sites with low and high disturbance. Co-occurrence of species was also mainly associated with response to disturbance. Similar responses to disturbance create two groups of species, those whose site-level occupancy usually increased as anthropogenic disturbance increased and those whose estimated occupancy decreased. The absence of large-bodied species entails an important loss of ecological function in disturbed areas and can hinder forest development and maintenance. Efforts to protect and restore forested landscapes are likely having a positive effect on the abundance of some threatened species. These efforts, however, must be sustained and expanded to increase connectivity and ensure the long-term viability of the wildlife community.