Field-scale modelling of carbon and nitrogen dynamics in soils amended with urban waste composts

Composting has emerged as a valuable route for the disposal of urban waste, with the prospect of applying composts on arable fields as organic amendments. Proper management of urban waste composts (UWC) requires a capacity to predict their impacts on carbon and nitrogen dynamics in the field, an issue in which simulation models are expected to play a prominent role.Here, we used a deterministic soil-crop model to simulate C–N dynamics in an arable field amended with three types of UWC (green waste and sludge, biodegradable waste, and solid waste), and a reference amendment (farmyard manure). The model is a version of CERES in which the soil C–N module was substituted with the NCSOIL model, whose microbiological parameters were determined from either laboratory incubation data or biochemical fractionation in a previous paper. CERES was tested against data from a field trial set up in 1998 in the Paris area, and managed as a maize (Zea mays L.)–wheat (Triticum aestivum L.) rotation. Comparison of observed and simulated data over the first 4 years of the field trial showed that CERES predicted the soil moisture and inorganic N dynamics reasonably well, as well as the variations in soil organic C. In particular, the parameterization of UWC organic matter from biochemical fractions achieved a similar fit as the parameterization based on incubation data. Wheat yields were also correctly predicted, but a systematic under-estimation of maize yields pointed at an under-estimation of spring and summer mineralization of N by CERES.Simulated N fluxes showed that the organic amendments induced an additional leaching ranging from 1 to 8 kg N ha⁻¹ yr⁻¹, which can be related to the initial mineral N content of the amendments. After 4 years, the composts had mineralized 3–8% of their initial organic N content, depending on their stability. Composts with slower N release had higher N availability for the crops. CERES could thus be used to aid in selecting the timing of compost application, in relation to its stability, based on both environmental and agronomical criteria.     

Assessing the Vulnerability of Coastal Communities to Extreme Storms: The Case of Revere,MA., USA

Climate change may affect the frequency, intensity, and geographic distribution of severe coastal storms. Concurrent sea-level rise would raise the baseline of flooding during such events. Meanwhile, social vulnerability factors such as poverty and disability hinder the ability to cope with storms and storm damage. While physical changes are likely to remain scientifically uncertain into the foreseeable future, the ability to mitigate potential impacts from coastal flooding may be fostered by better understanding the interplay of social and physical factors that produce human vulnerability. This study does so by integrating the classic causal model of hazards with social, environmental, and spatial dynamics that lead to the differential ability of people to cope with hazards. It uses Census data, factor analysis, data envelopment analysis, and floodplain maps to understand the compound social and physical vulnerability of coastal residents in the city of Revere, MA, USA. This revised version was published online in August 2006 with corrections to the Cover Date.     

Costs of maternal care: infant-carrying in baboons

Summary Infant-carrying, the most costly form of primate parental care other than lactation, was investigated in savannah baboons of Amboseli, Kenya. Measurements of physical growth, counts and length of paces, and simultaneous records of carrying and locomotion were used to evaluate the time, distance, and energetic expenditure of infant-carrying. Finally, we modeled the energetics of independent infant locomotion and considered ontogenetic patterns in the alternative energetic costs of carrying versus independent infant locomotion under assumptions of complete nutritional dependency. The youngest infants were carried by their mothers during all travel and foraging, for a total of 8–10 km/day. By 8 months of age, both carrying time and distance were almost zero. However, daily carrying distance, unlike carrying time, did not decline in the first few months, because older infants were carried disproportionately during rapid travel and, consequently, for greater travel distances per unit carrying time. Females of low dominance rank carried their infants the most; the highest ranking mothers not only carried their infants least but biased their carrying against sons. Although carrying a growing infant is an increasingly costly behavior, during the period of nutritional dependence energetic costs to the mother are appreciably greater if an infant travels independently instead of being carried by its mother. Yet infants increased locomotor independence at a younger age than predicted by a simple model of maternal energetic efficiency. Trade-offs in energetic economy may enhance a mother's future reproduction at the expense of her present infant, may enhance survival of the present infant by promoting early acquisition of developmentally essential skills, or may suggest the importance of additional factors that influence the mother's and infant's behavior. Offprint requests to: J. Altmann     

水稻花药绒毡层特异表达启动子的分离与表达载体构建

从籼稻川75A(OryzasativaL.)黄化苗叶片中直接提取基因组总DNA.根据文献报道的水稻花药绒毡层特异启动子Osg6B序列设计引物,采用TouchdownPCR技术获得水稻花药绒毡层特异表达的启动子Tsp1,将该片段克隆在载体pMD18-TVector上转化到大肠杆菌JM109,并酶切和PCR验证.序列分析发现,该片段与Osg6B启动子同源性为96%,且具有真核生物启动子的多种特征序列,表明启动子Tsp1为来源于籼稻川75A中的水稻花药绒毡层特异表达的启动子.利用该启动子对本实验室保存的质粒pIB467和pIB009进行改造,构建了一个可产生新型雄性不育系的双元植物表达载体pJH401.图7参13     

Shifting foraging strategies in colonies of the social wasp Polybia occidentalis (Hymenoptera, Vespidae)

Social insect colonies can be expected to forage at rates that maximize colony fitness. Foraging at higher rates would increase the rate of worker production, but decrease adult survival. This trade-off has particular significance during the founding stage, when adults lost are not replaced. Prior work has shown that independent-founding wasps rear the first workers rapidly by foraging at high rates. Foraging rates decrease after those individuals pupate, presumably reducing the risk of foundress death. In the swarm-founding wasps, colony-founding units have many workers, making colony death by forager attrition less likely. Do swarm-founding wasps show similar shifts in foraging rates during the founding stage? We measured foraging rates of the swarm-founding wasp, Polybia occidentalis at four stages of colony development. At each stage, foraging rates correlated with the number of larvae present, which, in the founding stages, correlated with the number of cells in the new nest. Thus, foraging rates appear to be demand-driven, with the level of demand in the founding stage set by the size of nest that is constructed. During the founding stage, foraging rates per larva were high initially, suggesting that colonies minimize the development times of larvae early in the founding stage. Later in the stage, foraging rates decreased, which would reduce worker mortality until new workers eclose. This pattern is similar to that shown for independent-founding wasps and likely results from conflicting pressures to maximize colony growth and minimize the risk of colony death by forager attrition.     

WGH型格栅除污机电控系统设计与应用

针对目前一些污水处理入口处仍然采用人工打捞法或格栅机械仪表控制法而产生的各种故障及作业效率低等原因 ,设计了以MCS 5 1单片机为核心的电控系统设计方案 ,研究建立了相应的算法模式 ,并对其设计误差进行了分析 ,提出了保证设备安全和对事故隐患进行摆脱的方法 ,使用结果表明 ,完全可实现打捞过程自动控制及作业工况远程监控 ,提高了系统的安全可靠性及作业效率。该电控系统在同类设备技术中尚未见公开报道。     

高速公路降雨径流污染特征及其污染控制

随着高速公路的快速发展,路面降雨径流污染引起了越来越多的关注.从高速公路路面雨水径流中污染物成分及其影响因素、径流污染迁移模型和径流污染物对受纳水体水质的影响等方面,对路面降雨径流污染特征进行了综述,并从工程和非工程措施两方面比较了目前高速公路路面降雨径流污染治理措施的特点和适用条件,最后提出了进一步研究的建议,希望为有关方面的研究提供借鉴.     

鸭河口水库水体总氮、总磷预测研究

根据鸭河口水库受纳点源及面源污染负荷情况，选择枯水期为预测时期，采用迪隆模型对鸭河口水库水体总氮、总磷进行预测研究，为鸭河口水库水质保持和富营养化防治提供基础数据。     

高强度连作下露天菜地土壤次生盐渍化及其影响因素研究

采集佛山市南海区露天菜地表层土壤,测定其硝酸盐含量和全盐量,分析珠江三角洲典型区域蔬菜地土壤次生盐渍化的发生现状和原因,为制定合理的施肥和管理措施提供科学依据。结果表明,1)136个土壤样本硝态氮质量分数在1.070～854.4mg/kg,平均值为194.3mg/kg,有19.9%的土壤样本硝态氮质量分数超过300mg/kg,已达到极高水平;全盐质量分数在0.02～2.7g/kg,平均值为1.2g/kg,有12.5%的土壤样本全盐质量分数已超过2.0g/kg的轻度盐化标准。2)土壤硝态氮质量分数与全盐质量分数之间具有一定的相关性,经统计检验相关系数达极显著水准(r=0.5665,n=131,P<0.01)。3)高强度连作露天菜地土壤的硝态氮质量分数和可溶性盐分浓度已经接近多年塑料大棚水平。4)综合而言,导致土壤次生盐渍化的原因有气候条件、土壤质地、地下水位、灌溉方式、不合理施肥等,而过量施肥及高强度连作可能是引起南海区露天菜地土壤次生盐渍化的主要因素。