long-term environmental monitoring
1. continuity and reliability of information is only assured if it is gathered or produced in a consistent and well documented manner. the most detailed examples are in the chemical sciences where an analytical measurement is the result of following a precisely defined method or process. deviation from the method or its components will often compromise the outcome and adherence to specification and is therefore critical for ensuring reliability of results. in many cases, the way in which the component parts of an experiment or data collection exercise are combined is as important as the correct implementation of the individual parts, and this aspect is often susceptible to operator differences in interpretation. to ensure similarity in scientific investigation .or monitoring, nationally and internationally agreed standards are being introduced. several systems of documenting experimental methods and procedures are in use today and are becoming increasingly important for indicating data quality and verifying the integrity of studies. one such approach is good laboratory practice which was introduced in 1982 by the health and safety executive to monitor the testing of industrial chemicals. since 1982 the range of laboratories inspected has been extended to include those working with pharmaceuticals, agrochemicals, cosmetics and food additives. good laboratory practice is concerned with the way laboratory or field studies are planned, monitored, recorded and reported and the conditions under which this occurs. following the principles' of glp ensures that the studies are properly planned, can be adequately carried out and are fully and accurately reported. as part of the planning, execution and reporting of a study, the various processes carried out are carefully documented as standard operating procedures.
2. the value of long-term observation of environmental factors has only been recognized relatively recently although some monitoring of the environmental factors have been in existence for over a century. the best known long-term study is probably the broadbalk experiment at rothamsted. broadbalk and the other long-term experiments at rothamsted and elsewhere are now proving to be extremely valuable by answering questions not considered, nor even conceived, when they were originally set up. even so they are limited in geographic scope and by the fact that they are confined to one land use category. current environmental and ecological monitoring networks, while not limited geographically, have in the main been set up to measure just one aspect of the environment. in contrast, the environmental change network (ecn) was set up to give added value to long-term monitoring and data collection by providing a network of sites in different parts' of the u.k. and under a variety of land use conditions where comparable long-term data on a wide variety of environmental variables could be recorded.
3. the idea of a network such as ecn was first considered in the mid 1970s but the concept did not reach fruition until 1992. the selection of the initial network of terrestrial sites was based on a range of criteria. one of the most important requirements, given the intended long-term nature of the project, was financial security although consistent quality of research was also required. the project intended that other sites representing more variable climate zones and land use will eventually join the network as funding becomes available.
4. the monitoring carded out at each ecn site covers a range of physical, chemical and biological measurements. where possible procedures and measurements used by existing national monitoring schemes are employed so that ecn provides an integrating function for the more extensive sectorial networks. environmental changes due to factors such as climate change are likely to be difficult to identify against the background noise arising from the numerous sources, both natural and man-made, of environmental variability. it is desirable, therefore, to minimize any additional variation due to operator involvement. to this end, and to ensure consistency and repeatability, protocols for each of the key measurements were produced. as an extension of the soil protocol, specific sops were written to further define the method and to reduce the likelihood of errors being introduced by different investigators during the life of the project. the terrestrial protocols have now been in place for four years ant[ act as blueprints for monitoring and data collection.
5. measurement inconsistency arises from a variety of causes, most of which occur only occasionally, if at all, in short-term or experimental studies but are almost inevitable in long-term studies.
6. advances in knowledge often initiate changes in standard methods as better procedures or instrumentation are developed. an old method can either be retained for comparability with previous results or changed to provide increased accuracy or reduced cost.
参考译文：环境的长期监控
1．以统一和实证的方法采集和推导的信息才具有连续性和可靠性。化学 分析测定方法采用了精确定义的方法或过程，因此提供了最详细的实例。方 法或成分的偏差往往会损害实验结果，因此严格按照规定，对确保结果的可 靠性至关重要。在许多情况下，实验步骤或者采集数据过程的组合方法与正 确地实施每一单个步骤一样重要。这方面容易受操作者在解释过程中的差异 的影响。为了确保科学调查和监控的相似性，引入了国内和国际一致的标准。 现在使用的几套记录实验的方法和过程，对表明数据的质量和验证研究的完 全性起着越来越重要的作用。其中一套是1982年由健康及安全委员会颁布的 “优良实验室条例”，用于监控测试工业化学品。自1982年以来，受检查的 实验室扩展到药品、化肥、化妆品和家用食品添加剂等实验室。“优良实验室 条例”涉及实验的设计、监控、记录、报告以及进行上述工作的实验条件。 根据此条例进行实验，确保了合理的研究计划、充分的实验过程和全面精确 的报告。作为实验的计划、实施和实验报告的一部分，不同的实验过程被当 作标准操作程序记载。
2．尽管环境监控已进行了一个多世纪，但是直到最近人们才认识到长期 观察环境因素的价值。最著名的长期研究实例可能是罗斯目斯坦德地区的“宽 障碍”实验。在这一地区进行的本次实验以及其它实验都是非常有价值的， 能够解答起初没有考虑，甚至没有想到的问题。即使如此目前的环境实验受 到地理范围的局限，限定于同一土地类型。目前建立的环境和生态监测网络， 尽管不受地理的限制，但是主要是测定环境的一个方面。相反，过去建立的 环境变化网络，通过提供英国不同地区定点网络，进一步增强了长期监控及 数据采集的重要价值。而且这些监测和数据采集是在不同地区条件下进行的。 不同土地条件下，基于多项环境变量的、可比较的长期数据得以记录下来。 3．诸如环境变化网络等网络概念是七十年代提出的，但直到1992年才付 诸实施。选择地表位置的初始网络是建立在—定标准范围基础之上。尽管研 究的—致性是必要的，但在研究项目的长期性质已定的情况下，财政保障是 最重要的条件之一。在资金允许的情况下，网络项目最终应力求包括代表更 有差异的气候区和土地使用。
4．在每一个环境变化网络地区进行的监控都包括一定范围的物理、化学 及生物测量。在可能的情况下，应该应用现在国家或国际监控方案中的程序 或测量标准，因而环境变化网络为更广泛的区域网络提供综合函数。在众多 自然及人为因素产生的环境变异源导致的噪音背景下，因气候变化等因素造 成的环境变化很难确定。因此，较为理想的是尽可能减小操作员产生的变量。为了达到这一目的，确保一致性和可重复性，制定了每种关键测量方法的草 约。作为土地草约的扩展，专门制定了具体的标准操作规程，以进一步确定 测量方法，从而减少工程过程中不同测量者产生误差的可能性。陆地草约已 存在了四年，且已成为监控及收集数据的蓝图。
5．测量的不一致性因多种原因而产生。其中大多数即使出现，也只是在 短期或实验室中偶然出现，但是在长期实验中不可避免。
6．随着更合理的程序或研究手段的开发，知识的进步往往能引起标准方 法发生变化。以前的方法要么继续保留，用于与以前的结果作比较，要么为了获得更高的精确度和更低的成本而改变。