Tracking changes in nutrient delivery to western Lake Erie: Approaches to compensate for variability and trends in streamflow
Tracking changes in nutrient delivery to western Lake Erie: Approaches to compensate for variability and trends in streamflow
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DOI：
10.1016/j.jglr.2018.11.012
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发表时间：
2019-02-01
影响因子：
2.2
通讯作者：
Confesor, R. B., Jr.
中科院分区：
文献类型：
--
作者：
Choquette, A. F.;Hirsch, R. M.;Confesor, R. B., Jr.
跟踪流营养物质输入伊利湖在几十年的时间尺度上的变化取决于使用的统计方法，可以删除流量的年际变化的影响，但也明确考虑流量的长期趋势的影响。本文介绍的方法包括一个扩展版本的加权回归时间，流量和季节（WRTDS）建模，明确考虑非平稳径流纳入信息的频率分布的变化，每日测量流量（流量）随着时间的推移。伊利湖西部流域五个长期监测点的年流量标准化通量（负荷）中可溶性活性磷（SRP）趋势显示，1995年至2015年期间增加了109%至322%。约三分之一的增加似乎归因于排放趋势的增加，而其余三分之二似乎是由浓度与排放关系的变化所驱动的，反映了近年来任何特定排放的浓度较高。总磷和三个氮参数（总氮，硝酸盐-亚硝酸盐，和总凯氏氮）在10个网站分析的趋势是不太明显，通常显示减少的浓度-排放量的关系，伴随着排放量的增加，导致总通量的净变化不大。每月SRP通量和排放量的趋势，溶解与颗粒组分的营养物质，和N：P通量比进行了评价。这里描述的方法提供了更清楚地辨别营养控制策略的有效性的工具，可以作为实现营养减少目标的进展或缺乏进展的持续措施。Elsevier B. V.代表国际五大湖研究协会出版。
Tracking changes in stream nutrient inputs to Lake Erie over multidecadal time scales depends on the use of statistical methods that can remove the influence of year-to-year variability of streamflow but also explicitly consider the influence of long-term trends in streamflow. The methods introduced in this paper include an extended version of Weighted Regressions on Time, Discharge, and Season (WRTDS) modeling that explicitly considers nonstationary streamflow by incorporating information on changes in the frequency distribution of daily measured streamflow (discharge) over time. Soluble reactive phosphorus (SRP) trends in annual flow-normalized fluxes (loads) at five long-term monitoring sites in the western Lake Erie drainage basin show increases of 109 to 322% over the period 1995 to 2015. About one-third of the increase appears attributable to increasing discharge trends, while the remaining two-thirds appears to be driven by changes in concentration versus discharge relationships reflecting higher concentrations for any given discharge during recent years. Trends in total phosphorus and three nitrogen parameters (total nitrogen, nitrate-nitrite, and total Kjeldahl nitrogen) at the 10 sites analyzed were much less pronounced, and commonly show decreases in concentration-discharge relationships accompanied by increases in discharge, resulting in little net change in total flux. Trends in monthly SRP fluxes and discharge, dissolved versus particulate fractions of nutrients, and N:P flux ratios were also evaluated. The methods described here provide tools to more clearly discern the effectiveness of nutrient-control strategies and can serve as ongoing measures of progress, or lack of progress, towards nutrient-reduction goals. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research.