Trends of organic carbon in Scottish rivers and lochs
Trends of organic carbon in Scottish rivers and lochs
复制标题
苏格兰河流和湖泊有机碳的趋势
DOI：
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
S. Reid
中科院分区：
文献类型：
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作者：
S. Reid
在苏格兰，苏格兰环境保护局（SEPA）是负责监测水质并向苏格兰和英国政府以及欧洲共同体报告的监管机构。为了改善河流和洛克斯等地表沃茨的水质，欧洲议会在过去二十年中制定了指令，概述了营养水平和水质状况的目标。Moxley（2010）指出，苏格兰许多河流中的有机碳浓度在过去20年中大约翻了一番，土壤是最可能的来源。根据Moxley（2010年）的说法，所有浓度增加的地点的平均总有机碳（TOC）增加率为每年每升0.12毫克（mg/l/y）。这意味着TOC浓度在20年期间增加了近2.5 mg/l。因此，在苏格兰的河流和洛克斯的有机碳的行为已成为感兴趣的，是本论文分析的重点。
第1章介绍了有机碳，提供了一个洞察观察到的趋势，在英国，而且，世界其他地区。此外，第1章讨论了被认为与有机碳水平变化有关的环境和物理因素。此外，第1章还介绍了所使用的数据和抽样技术。第2章中的探索性分析表明，河流和洛克斯中的TOC对数水平一直在增加，直到21世纪初，TOC对数遵循季节性模式。此外，探索性分析揭示了高水平的总有机碳和溶解有机碳之间的关联。探索性分析还强调了协变量的问题;因此，第2章探讨了处理检测限值以及适当插补缺失值的适当方法。
第3章探讨了在选定的河流和洛赫网站的日志TOC，以及日志TOC和协变量之间的关系，在每个网站的细节。此外，第3章探讨了使用不同的回归技术（如线性和加法建模），以适当地捕捉日志TOC在每个站点的行为。第4章从调查和模拟个别网站，探索网站以某种方式连接。第4章认为，日志TOC的行为在网站的一部分，迪河网络，每个站点之间的距离，以及如何河流之间的流动，每个站点都必须考虑在内。第4章调查的行为日志TOC在整个河流网络的时间和空间的视觉，但也探讨了适当的建模技术，适当捕捉日志TOC在时间和空间的行为，考虑到适当的协变量，合理地解释所观察到的趋势。
第5章讨论了论文的主题：一致性在那里被定义和探讨。进行了文献综述，以考虑可能的方法来测量相干性。季节性的曼恩-肯德尔测试被认为是一个适当的方法来衡量一组网站的异质性和动态因子分析被认为是一种有效的技术，确定共同的趋势，在一组网站，因此，这些方法被应用在第5章测量的一致性水平的网站在迪河网络，而且，网站位于同一个苏格兰地区。从第5章中进行的分析，第6章的目的是适当建模的日志TOC在苏格兰地区的水平，考虑到时间和空间，而且，可能的协变量被认为是推动这种趋势。最后，第7章总结了研究结果，并讨论了研究的局限性和未来可能的研究领域。
In Scotland, the Scottish Environment Protection Agency (SEPA) is the regulatory agency responsible for monitoring water quality and reporting back to the Scottish and UK governments and the European community. In order to improve water quality in surface waters such as rivers and lochs, the European Parliament has established directives over the past twenty years outlining targets for nutrient levels and water quality status. Moxley (2010), states that the concentration of organic carbon in many Scottish rivers, has approximately doubled over the last twenty years, with soils being the most likely source. According to Moxley (2010), the rate of total organic carbon (TOC) increase, averaged across all sites with increasing concentrations, was 0.12 milligrams per litre per year (mg/l/y). This is an increase in TOC concentration of nearly 2.5 mg/l over a twenty year period. Consequently, the behaviour of organic carbon in Scottish rivers and lochs has become of interest and is the focus of analysis within this thesis.
Chapter 1 introduces organic carbon, providing an insight into observed trends in the United Kingdom, but also, other parts of the world. Furthermore, Chapter 1 discusses environmental and physical factors which are thought to be associated with changing levels in organic carbon. Moreover, Chapter 1 provides a description of the data and sampling techniques which have been used. The exploratory analysis in Chapter 2 reveals that the log TOC levels in rivers and lochs have been increasing up until the early 2000’s, and that the log TOC follows a seasonal pattern. Furthermore, the exploratory analysis reveals the high level of association between total organic carbon and dissolved organic carbon. The exploratory analysis also highlighted issues with the covariates; therefore Chapter 2 explores suitable methods of dealing with values at the limit of detection, as well as appropriately imputing missing values.
Chapter 3 explores log TOC at a selection of river and loch sites, and the relationship between log TOC and covariates at each site in detail. In addition, Chapter 3 explores the use of different regression techniques (e.g. linear and additive modelling) in order to appropriately capture the behaviour of log TOC at each site. Chapter 4 progresses from investigating and modelling individual sites, to exploring sites which are connected in some manner. Chapter 4 considers the behaviour of log TOC in sites which are part of the River Dee network, where the distance between each site and how the river flows between each of the sites had to be taken into consideration. Chapter 4 investigates the behaviour of log TOC across the river network over time and space visually; but, also explores appropriate modelling techniques which suitably capture the behaviour of log TOC over time and space, taking into consideration suitable covariates to plausibly explain the observed trends.
Chapter 5 addresses the main theme of the thesis: coherency is defined and explored there. A literature review was conducted to consider possible methods of measuring coherency. The seasonal Mann-Kendall test was found to be an appropriate method of measuring the heterogeneity of a group of sites; and dynamic factor analysis was found to be an effective technique of identifying common trends in a group of sites; hence, these methods were applied in Chapter 5 to measure the level of coherency between sites in the River Dee network, but also, sites located in the same Scottish region. Progressing from the analysis carried out in Chapter 5, Chapter 6 aims to appropriately model the levels of log TOC in Scottish regions, taking into account time and space, but also, possible covariates thought to be driving such trends. Finally, Chapter 7 provides a summary of the findings, and discusses limitations of the study and possible areas of future research.
影响因子：
4.8
作者：
Polansky L;Wittemyer G;Cross PC;Tambling CJ;Getz WM
通讯作者：
Getz WM