土地利用对水体营养物影响的研究进展

日益严重的水质污染威胁到人类健康与生存,水体富营养化是其中一大治理难题。流域土地利用深刻影响水体中的营养物,定量刻画两者关系,可有效指导土地利用优化以改善水体质量。在国内外研究的基础上,本文梳理了样地实验、统计分析、经验模型和机理模型等4类研究土地利用和水体营养物关系的方法,并分析了不同方法应用的优缺点。以往研究多侧重土地利用数量结构,对强度和空间分布的量化及其与水体营养物关系的模型构建等研究尚显不足,多从单一或部分信息进行松散研究,导致不同研究中土地利用对水体营养物的解释能力差异显著。本文着重综述土地利用类型、强度差异和空间分布等3个方面对水体营养物影响的研究进展,并阐述关于两者定量关系尺度效应的争议和不确定性。目前主要存在问题包括现有研究土地利用和水体营养物的关系手段不足、土地利用多组分信息和水体营养物关系规律不清和尺度效应不确定性等3方面。因此,本文以水体污染物的产生、迁移、转化等的生态水文过程为线索,提出土地利用多信息空间综合表达和量化研究框架作为核心突破口。应用该框架,未来围绕融合过程机理与经验统计的模型开发、富营养化过程关联的土地利用多信息综合量化和多尺度结构的构建等3个方面开展研究,旨在为丰富土地利用对水体营养物影响研究提供一定的参考价值。     

Vertical distribution of larval Atlantic menhaden (Brevoortia tyrannus) and Atlantic croaker (Micropogonias undulatus): Implications for vertical migratory behaviour and transport

Understanding the interactions among biological and physical processes is essential to determining how the environment affects transport and survival of fishes. We examined vertical distribution in larval Atlantic menhaden (Brevoortia tyrannus) and Atlantic croaker (Micropogonias undulatus) using 126 depth stratified tows in Delaware Bay, USA, during two cruises, in December 2007 and February 2008. Menhaden larvae were 16.8–24.6 and 20.5–26.2 mm standard length in December and February. Corresponding lengths for croaker were 9.3–17.9 and 8.6–19.6 mm. Using empirical observations, and statistically derived models, we explored larval concentration for both species as a function of location, depth, diel period, tidal period, size, and pairwise interactions. Menhaden concentration was best modeled as a function of station, cruise, and interactions between depth and size as well as between station and cruise. No significant differences in larval menhaden concentration were present among tidal and diel periods. Croaker concentration was best modeled as a function of size and interactions between station and diel period, depth and size, cruise and size. Despite tidal period not emerging as a significant model parameter, we observed larger croaker larvae during nighttime flood tides. Our statistical models are consistent with processes of up‐estuary transport for both species, suggesting larvae are increasingly affected by behavioral responses as larvae grow, exhibiting stronger patterns in vertical distribution. The results refine our understanding of the potential importance of size‐related differences in vertical distribution for larval transport in these species. Future research should examine the interactions among size‐specific vertical migratory capabilities, vertical distribution, transport, and retention.     

竹蚜空间格局及其抽样技术初步研究

采用聚集度指标等方法测定并分析竹蚜空间格局 ,结果表明 :竹蚜 Astegopteryx bambusae在林间呈聚集分布 ,其个体间相互吸引 ,分布的基本成份是个体群 ,聚集度随种群密度的升高而增大 .同时 ,应用 Iwao统计方法 ,计算了不同种群密度下最适抽样数及序贯抽样     

三江平原环型湿地土壤养分的空间分布规律

以三江平原环型湿地作为研究对象，对其环带状植被区湿地土壤的有机碳、全氮、全磷和全钾的空间分布规律进行了初步研究。结果表明，环型湿地土壤有机碳、全氮、全磷和全钾具有明显的空间水平分异规律，有机质、全氮、全磷的含量由环型湿地中心向边缘逐渐减少，全钾的含量和碳氮比逐渐增加。土壤有机碳、全氮、全磷和全钾在垂直方向上具有明显的分层和富聚现象，自上而下，有机质的含量逐渐降低；全氮含量除漂筏苔草群落外，其他各群落土壤全氮含量呈先增加后减少的分布；大部分植物群落全磷含量呈先减后增的“V”型分布；全钾含量呈表层和底层较高、中间层较低的“中空”状分布。通过相关分析表明，环型湿地土壤有机碳与全氮具有相似的空间分布规律，全钾与有机碳、全氮具有相异的空间分布规律，而全磷具有自己独特的空间分布规律。环型湿地土壤的有机碳、全氮、全磷和全钾的空间分布主要受植物体元素含量、生物过程和水文地貌过程影响，它通过过程影响湿地的功能。研究环型湿地的有机碳、全氮、全磷和全钾的空间分布规律不仅有助于完善湿地土壤形成和发育的理论，探明湿地的生态过程和功能，而且为合理利用和保护湿地提供科学依据。     

Spatial distribution of Antarctic minke whales (Balaenoptera bonaerensis) in relation to spatial distributions of krill in the Ross Sea,Antarctica

The spatial distribution of Antarctic minke whales in the Ross Sea with relation to spatial distributions of their prey – krill – was investigated in this study using generalized additive models (GAMs). Spatial distributions of two species of krill (ice and Antarctic krill) were estimated by GAMs. Three abiotic factors – distance from the continental shelf break (800 m isobaths), the mean temperature and salinity from the surface to 200 m (MTEM‐200 and MSAL‐200), and latitude and longitude – were used as covariates for models of krill. Estimated spatial distributions of krill were then used with other covariates to model the spatial distribution of Antarctic minke whales. In the selected model of Antarctic minke whales, Antarctic krill were more influential than ice krill. The number of Antarctic minke whales increased as the density of Antarctic krill increased to around 1.5 g m^?2. Beyond that, the number of Antarctic minke whales decreased as the density of Antarctic krill increased. High densities of the Antarctic minke whales were estimated along the sea ice edge in the eastern part of the Ross Sea. Specifically, the densities were high in the north of the continental shelf break where low MTEM‐200 and MSAL‐200 and intermediate densities of Antarctic krill were observed. Further data collection is needed to investigate interannual variations and trends in their relationship. The results show that the spatial distribution of Antarctic minke whales is a function of longitude, distance from the shelf break, oceanographic condition (temperature and salinity), and densities of ice and Antarctic krill.     

农电企业配电网GIS系统空间数据库设计

农电企业配电网络数据类型复杂、数据量大,如何合理组织配电系统的数据,为配电GIS系统的高级分析功能或企业层决策提供支持,进而配电网GIS系统设计的关键问题。文章介绍了配电网GIS系统数据组织、数据采集方法及空间数据库构建方法,满足系统需求。     

湘中紫色页岩区芦竹生物量及养分分布规律研究

对湘中紫色页岩区芦竹的生物量和养分分布进行初步研究.结果表明:当年生芦竹杆(含叶)养分含量高于多年生,因此不宜砍伐利用当年生芦竹杆;根茎养分含量较高,是系统中良好的养分贮存库.一年生、二年生、五年生、八年生芦竹的生物量分别为293.00、5258.29、6746.87和480.86 kg.hm-2.     

匀加速直线运动中柔索的张力分布及其稳定形状

本文以一段考虑自重的柔索牵引一质点作匀加速直线运动为模型，采用拖力端柔索为水平的边界条件近似，求得了柔索中张力沿弧长的分布函数，以及柔索稳定形状的参量表达式，并将所有结果与悬链线进行了有意义的比较。     

NaCl胁迫下栽培型番茄Na+、K+吸收、分配和转运特性

【目的】明确盐分胁迫下栽培型番茄离子吸收、分配和转运特性。【方法】以栽培番茄为试材,以NaCl溶液为盐分胁迫条件,通过苗期耐盐性鉴定,采用原子吸收光谱法测定不同耐盐性番茄品种体内离子含量,对盐分胁迫下番茄体内离子积累、分布和转运机制进行系统分析。【结果】番茄对Na+的吸收随盐分处理浓度和时间的增加而增加,在各器官的积累量顺序为根＞茎＞叶。对于较耐盐品种,Na+在体内的积累总量低于盐敏感品种。盐分胁迫后,番茄叶片、茎和根系中Na+/K+比均随NaCl浓度的升高而升高。耐盐品种的Na+/K+比低于盐敏感品种。离子在体内的区域化分布情况是,较耐盐品种的Na+在根茎中的分配比例较高,盐敏感品种趋向于向叶片分配。K+在较耐盐品种的分布集中于叶片。在盐胁迫初期,盐分处理浓度超过200 mmol•L-1时,番茄植株对K+向地上部的选择运输性随着胁迫时间的延长呈现出下降的趋势。低于200 mmol•L-1时,表现出很好的选择运输性,耐盐品种的Sk/Na(运输)高于盐敏感品种,根系表现出更强的向地上部运输K+的能力。【结论】盐分胁迫下,叶片中较低的Na+含量和更强的向地上部运输K+的能力是番茄耐盐性的重要特征。     

An assessment of carcass counting surveys with increasing time lapse following a simulated fish kill on a small upland stream

A simulated fish kill was conducted on a small upland stream in Northern Ireland by planting out hatchery‐produced brown trout Salmo trutta L. carcasses of various size categories. Standard, post‐fish kill, assessment walkover surveys were conducted over time intervals to determine the number of carcasses visible. The sample variance between individual surveyors was generally low, with good agreement between the observed counts for the three, discrete, size fractions of fish up to 72 hr after the simulated fish kill. Despite low discharge rates, shallow water and good accessibility to the experimental stream, only 52% of the small category fish (<8 cm L_F) were recorded 4 hr after the start of the simulated fish kill. Larger carcasses (>17 cm L_F) were more visible, and >90% were detected 48 hr after the start of the simulated fish kill. After 96 hr, all size fractions of carcasses had reduced significantly, and the variability between replicate surveys increased markedly.