کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5750085 | 1619690 | 2018 | 10 صفحه PDF | دانلود رایگان |
- Substantial, long-term declines in TP were detected in boreal lakes across Sweden.
- Lake trophic status has changed in many lakes to ultra-oligotrophic.
- Increased reliance on forest biomass and hydropower will likely exacerbate P declines.
- Legislation is poorly equipped to handle impairments caused by oligotrophication.
We present an analysis of long-term (1988-2013; 26 years) total phosphorus (TP) concentration trends in 81 Swedish boreal lakes subject to minimal anthropogenic disturbance. Near universal increases in dissolved organic carbon (DOC) concentrations and a widespread but hitherto unexplained decline in TP were observed. Over 50% of the lakes (n = 42) had significant declining TP trends over the past quarter century (Sen's slope = 2.5% yâ 1). These declines were linked to catchment processes related to changes in climate, recovery from acidification, and catchment soil properties, but were unrelated to trends in P deposition. Increasing DOC concentrations appear to be masking in-lake TP declines. When the effect of increasing DOC was removed, the small number of positive TP trends (N = 5) turned negative and the average decline in TP increased to 3.9% yâ 1. The greatest relative TP declines occurred in already nutrient poor, oligotrophic systems and TP concentrations have reached the analytical detection limit (1 μg Lâ 1) in some lakes. In addition, ongoing oligotrophication may be exacerbated by increased reliance on renewable energy from forest biomass and hydropower. It is a cause of significant concern that potential impairments to lake ecosystem functioning associated with oligotrophication are not well handled by a management paradigm focused exclusively on the negative consequences of increasing phosphorus concentrations.
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Journal: Science of The Total Environment - Volumes 613â614, 1 February 2018, Pages 240-249