Compared performances of different algorithms for estimating annual nutrient loads discharged by the eutrophic River Loire
Compared performances of different algorithms for estimating annual nutrient loads discharged by the eutrophic River Loire
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评估富营养化卢瓦尔河每年排放的养分负荷的不同算法的性能比较
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发表时间：
2005
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通讯作者：
M. Meybeck
中科院分区：
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作者：
F. Moatar;M. Meybeck
地球系统科学和水质管理需要对污染物通量进行良好的估计。过去几十年来水质数据记录的逐渐积累增加了这些数据用于研究长期趋势的价值。然而，在许多主要河流上，大多数污染物的采样不频繁，使得流量估算及其分析变得困难。本文探讨了估算养分通量的不同方法的性能。目的是根据每月采样评估年度养分通量的准确性（偏差）和精度（离散度），这是自 1971 年以来法国 80% 水质调查的频率。该研究基于在法国卢瓦尔河中游奥尔良站进行的为期 5 年的试点研究（1981-85 年）期间高频次调查的养分浓度数据集。平均比通量为 641（硝酸盐-N）、96（总磷）和 37 kg-1 km-2（正磷酸盐-P）。然后，每年通过随机模拟 12 个采样日期对数据集进行“重新采样”。生成了 100 个模拟每月样本，并测试了七种估计方法。评估表明，当大河流中特定物质的浓度呈现季节性变化时，建议采用基于大约每月间隔采集的样本之间的线性插值的简单方法。在每月采样间隔内，通过适当的方法获得的年养分通量的精度（置信度为 95%）为：硝酸盐为 13%，总磷为 20%，正磷酸盐为 26%，颗粒磷为 34%。获得精度为 10% 的年度养分通量所需的水质调查频率对于硝酸盐而言约为 15 天，对于正磷酸盐-P 和总磷而言约为 10 天，对于颗粒物-P 而言约为 5 天。版权所有 © 2004 约翰·威利父子有限公司
Good estimates of pollutant fluxes are required for Earth systems sciences and water quality management. The gradual accumulation of water quality data records over the past few decades has increased the value of these data for examining long‐term trends. On many major rivers, however, infrequent sampling of most pollutants makes flux estimates and their analysis difficult. This paper explores the performance of different methods for estimating nutrient fluxes. The objective is to assess the accuracy (bias) and precision (dispersion) of annual nutrient fluxes based on monthly sampling, which is the frequency with which 80% of French water quality surveys have been carried out since 1971. The study is based on a data set of nutrient concentrations surveyed at high frequency during a 5 year pilot study (1981–85) at the Orléans station in the middle reaches of the River Loire, France. The mean specific fluxes were 641 (nitrate‐N), 96 (total‐P) and 37 kg year−1 km−2 (orthophosphate‐P). For each year, the data set was then ‘resampled’ by randomly simulating 12 sampling dates. 100 simulated monthly samplings were generated, upon which seven estimation methods were tested. The evaluations indicate that, when concentrations of specific substances in large rivers exhibit seasonal variation, a simple method based on linear interpolation between samples taken at approximately monthly intervals is advocated. With the monthly sampling interval, the precision (confidence level of 95%) of annual nutrient fluxes obtained by the appropriate methods was 13% for nitrates, 20% for total‐P, 26% for orthophosphates, and 34% for particulate‐P. The frequency of water quality surveys required to obtain an annual nutrient flux with 10% precision was around 15 days for nitrate, 10 days for orthophosphate‐P and total‐P, and about 5 days in the case of particulate‐P. Copyright © 2004 John Wiley & Sons, Ltd.