A methodological framework for integrating computational fluid dynamics and ecological models applied to juvenile freshwater mussel dispersal in the Upper Mississippi River

Interdisciplinary research in hydraulics and ecology for river management and restoration must integrate processes that occur over a wide range of spatial and temporal scales, which presents a challenge to ecohydraulics modelers. Computational fluid dynamics (CFD) models are being more widely used to determine flow fields for ecohydraulics applications. In the Upper Mississippi River (UMR), the mussel dynamics model was developed as a tool for management and conservation of freshwater mussels (Unionidae), which are benthic organisms, imperiled in North America, that are inextricably linked with the hydraulics of river flow. We updated the juvenile dispersal component of the mussel dynamics model by using stochastic Lagrangian particle tracking in a three dimensional flow field output from CFD models of reaches in the UMR. We developed a methodological framework to integrate hydrodynamic data with the mussel dynamics model, and we demonstrate the use of the juvenile dispersal model employed within the methodological framework in two reaches of the UMR. The method was used to test the hypothesis that impoundment affects the relationship of some hydraulic parameters with juvenile settling distribution. Simulation results were consistent with this hypothesis, and the relationships of bed shear stress and Froude number with juvenile settling were altered by impoundment most likely through effects on local hydraulics. The methodological framework is robust, integrates Eulerian and Lagrangian reference frameworks, and incorporates processes over a wide range of temporal and spatial scales, from watershed scale hydrologic processes (decades), to reach scale (km) processes that occur over hours or days, and turbulent processes on spatial scales of meter to millimeter and times scales of seconds. The methods are presently being used to assess the impacts of pre- and early post-settlement processes on mussel distributions, including the effects of bed shear stress, and the sensitivity of the location of the host fish when juveniles excyst, on juvenile settling distribution.     

Accuracy and traceability concepts applied to environmental speciation analysis

Traceability issues are of increasing concern in all fields where chemical measurements form the basis for decisions. The concepts of accuracy and traceability as applied to environmental analysis are, however, still prone to misunderstandings, which has been recently illustrated by controversial discussions among the analytical community with respect to accuracy and traceability issues in the area of speciation analysis. Analytical techniques used for the determination of chemical species (speciation analysis) are generally based on a succession of steps (e.g. extraction derivatisation, separation, detection) which are all prone to various sources of systematic errors. Many speciation measurement techniques have been studied within the last decade through interlaboratory studies and certification of reference materials. These collaborative efforts have been understood as being directed towards strive for accuracy (trueness and precision). It has been recognised recently that the achievements actually enabled mostly to establish reference points (e.g. certified values in reference materials) which does not necessarily correspond to 'true values' but rather offer a mean for laboratories to compare their data internationally and, hence, achieve traceability. This ambiguity still generates confusion and misunderstandings among the scientific community. This communication discusses this issue, focusing on analytical measurements only. Extending discussions on general traceability issues would imply an examination of steps prior to laboratory work (sampling, storage, etc.) which is beyond the scope of this contribution.     

环境监测实验室标准物质的使用和管理中应关注的几个问题

从实验室认可和计量认证的需求出发,按照《检测和校准实验室能力认可准则》（简称《准则》）要求,对环境监测实验室如何正确使用和规范管理标准物质,保证监测数据的准确性、溯源性进行探讨。     

制定湖泊营养物基准的技术方法研究进展

湖泊营养物基准是指用可信的科学数据表示水中营养物的允许浓度和生态指标的阈值,是制定富营养化标准、评价湖泊状态依据。文章分析了国外制定湖泊营养物基准的方法:参照状态法、输入-响应模型法和机理推断法,并概述了目前湖泊富营养化预测模型。通过分析对比,提出了适合我国湖泊营养物基准制定的技术方法及思路。     

含13种有机氯农药土壤标准样品的研制

采用分级稀释混合法将来自不同采样点的含不同种类和浓度的有机氯农药(OCPs)的样品进行混合制得含13种OCPs的土壤标准样品。根据GB/T 15000《标准样品工作导则》系列标准对土壤标准样品进行均匀性检验、稳定性检验,并和16家实验室协作定值。实验结果表明:土壤标准样品中13种OCPs指标均匀性良好,保证土壤标准样品足够均匀的最小取样量为0.50 g;在室温(不超过30℃)避光贮存条件下,在为期12个月的稳定性检验期间,该土壤标准样品中13种OCPs稳定性良好。该土壤标准样品中13种OCPs指标的含量范围为0.08~5.23μg/g,扩展不确定度为0.014~0.82μg/g,基本满足我国土壤、沉积物等环境样品中OCPs的质量控制检测需求。     

大气环境建模与仿真中的公共基础技术研究

大气环境是综合自然环境(SNE)的重要组成部分.基于SNE建模与仿真的关键技术,定义了大气环境概念参考模型,提出了一种面向直升机飞行仿真的大气环境数据模型,探讨了大气环境内部模型的选取开发方法,设计了"动态数据柱"形式的大气环境信息格式,并就大气环境建模的基本流程进行了初步探讨.     

河流健康评价中不同标准化方法的应用与比较

年5月与2010年5—6月对浑太河流域开展大型底栖动物野外生态调查,分别使用水质法(水质指标标准化法)、栖境法(栖息地质量评价指标标准化法)和综合法(水质与栖息地质量评价指标结合的标准化法)筛选参照点和受损点,构建IBI(生物完整性指数)以对研究区域的健康状况作出评价. 结果表明:不同标准化方法筛选的参照点与受损点不同,其中,水质法与栖境法筛选的参照点与受损点数量多于综合法. 不同标准化方法构建的IBI核心参数不同,仅有4个参数〔总分类单元数、EPT分类单元数(蜉蝣目、積翅目、毛翅目三目昆虫分类单元数之和)、耐污类群相对丰度和黏附者相对丰度〕为3种方法所共有. 不同标准化方法对河流健康的评价结果不同,其中,水质法与栖境法对浑太河健康状况的评价等级整体高于综合法. 比较不同标准化方法选择参照点的准确率可知,栖境法的准确率(75%)优于水质法(50%)和综合法(67%);而在选择受损点的准确率中,水质法(100%)和综合法(100%)均优于栖境法(89％).      

湖泊营养物参照状态建立方法研究

建立生态分区内各类型湖泊营养物的参照状态是营养物基准制定过程中最为核心的内容之一。在系统分析和评价国外确定湖泊营养物参照状态的若干种方法,包括参照湖泊法、湖泊群体分布法、三分法、回归分析等几种统计学方法以及模型推断和古湖沼学重建方法后,文章根据总磷（total phosphorus,TP）、总氮（total nitrogen,TN）、叶绿素a（chlorophyll a,Chl-a）和塞氏透明度（Secci depth）等四项指标的历史监测数据,应用若干统计学方法建立了巢湖的营养物基准参照状态。通过互相之间的比较分析以及长江中下游湖区古湖沼学重建数据的验证,推荐采用湖泊群体分布法5％点位对应的值作为巢湖营养物基准的参照状态。因此,巢湖营养物参照状态阈值范围为总磷0．023～0．27mg·L^-1,总氮O．62～0．63mg·L^-1,叶绿素aO．65～0．67mg·m^-1,塞氏透明度0．65-0．72m。     

某温湿高度试验箱低温-高度试验温度漂移原因分析与对策

目的针对某国产温湿高度试验箱,给出在低温-高度试验时,温度漂移的解决方法。方法在低温-高度试验时,对温度漂移原因进行研究分析,找出温度漂移的原因,给出了利用箱体微电脑触摸屏编程控制方法与设备控制参数设置的参考数据,找出了解决问题的简单方法。结果在低温(如-55℃)、低气压(如11.9 kPa)阶段,温度波动小于±3℃。结论通过设备控制参数重置,特别是通过一种拟合编程摸底试验,成功地解决了低温-高度试验时温度漂移问题。试验结果满足试验技术条件要求,并且节约了人力物力,为产品的交付使用赢得了时间。     

确定湖泊参照状态过程中频率分析的精度估计

确定湖泊参照状态是建立湖泊水质基准的关键步骤之一。以频率分析为基础的方法,如湖泊群体分布法、频率分析法、三分法等广泛地应用于参照状态的研究中;但是,由于湖泊观测数据具有关联性以及难以确定概率分布,这些研究都未给出参照状态估计的置信区间。滑块自助法无需确定观测数据的理论概率分布,同时能很好地克服数据关联性引起的问题,给出这些方法得到的参照状态的置信区间。以太湖为例,分析了确定频率分析过程中,正态分布法和普通自助法的缺陷;结果说明这一方法适合于确定湖泊参照状态的精度。