Canadian Rivers Institute, University of New Brunswick, Alberta, Canada.
Integr Environ Assess Manag. 2013 Jul;9(3):439-55. doi: 10.1002/ieam.1363. Epub 2013 Feb 14.
This article is the second in a 2-part series assessing the accumulated state of the transboundary Yukon River (YR) basin in northern Canada and the United States. The determination of accumulated state based on available long-term (LT) discharge and water quality data is the first step in watershed cumulative effect assessment in the absence of sufficient biological monitoring data. Long-term trends in water quantity and quality were determined and a benchmark against which to measure change was defined for 5 major reaches along the YR for nitrate, total and dissolved organic carbon (TOC and DOC, respectively), total phosphate (TP), orthophosphate, pH, and specific conductivity. Deviations from the reference condition were identified as "hot moments" in time, nested within a reach. Significant increasing LT trends in discharge were found on the Canadian portion of the YR. There were significant LT decreases in nitrate, TOC, and TP at the Headwater reach, and significant increases in nitrate and specific conductivity at the Lower reach. Deviations from reference condition were found in all water quality variables but most notably during the ice-free period of the YR (May-Sept) and in the Lower reach. The greatest magnitudes of outliers were found during the spring freshet. This study also incorporated traditional ecological knowledge (TEK) into its assessment of accumulated state. In the summer of 2007 the YR Inter Tribal Watershed Council organized a team of people to paddle down the length of the YR as part of a "Healing Journey," where both Western Science and TEK paradigms were used. Water quality data were continuously collected and stories were shared between the team and communities along the YR. Healing Journey data were compared to the LT reference conditions and showed the summer of 2007 was abnormal compared to the LT water quality. This study showed the importance of establishing a reference condition by reach and season for key indicators of water health to measure change, and the importance of placing synoptic surveys into context of LT accumulated state assessments.
本文是评估加拿大北部和美国育空河流域（YR）跨界流域累积状况的两部分系列文章中的第二部分。在缺乏足够的生物监测数据的情况下，基于可用的长期（LT）流量和水质数据来确定累积状态是流域累积效应评估的第一步。确定了 5 个主要河段的水量和水质长期趋势，并为硝酸盐、总有机碳（TOC 和 DOC）、总磷酸盐（TP）、正磷酸盐、pH 值和比导率定义了一个基准，用以衡量硝酸盐、总有机碳（TOC）和总磷酸盐（TP）在河源河段的变化。在时间上嵌套在一个河段内的“热点时刻”确定为偏离参考条件的时刻。在育空河的加拿大部分发现 LT 流量呈显著增加趋势。河源段硝酸盐、TOC 和 TP 呈显著 LT 下降趋势，下游段硝酸盐和比导率呈显著上升趋势。所有水质变量均偏离参考条件，但在育空河无冰期（5 月至 9 月）和下游段最为明显。离群值的最大幅度出现在春季融雪期。本研究还将传统生态知识（TEK）纳入其累积状态评估中。2007 年夏天，育空河流域部落间理事会组织了一组人沿着育空河全程划独木舟，作为“疗愈之旅”的一部分，其中使用了西方科学和 TEK 范式。连续收集水质数据，并在团队和育空河流域的社区之间分享故事。疗愈之旅数据与 LT 参考条件进行了比较，结果表明 2007 年夏季与 LT 水质相比异常。本研究表明，为衡量变化建立关键指标的参考条件至关重要，特别是在每个河段和每个季节建立参考条件；将综合调查置于 LT 累积状态评估的背景下也非常重要。
