Determining reference conditions for nutrients, chlorophyll a and Secchi depth in Yungui Plateau ecoregion lakes, China
| Autor: | Jing Su, Fengyu Zan, Danfeng Ji, Qi Chen, Beidou Xi, Shou-Liang Huo, Qigong Xu |
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| Rok vydání: | 2011 |
| Předmět: |
Hydrology
Chlorophyll a geography Environmental Engineering geography.geographical_feature_category Plateau Drainage basin Management Monitoring Policy and Law Plankton Structural basin Pollution chemistry.chemical_compound Ecoregion Nutrient chemistry parasitic diseases Environmental science Eutrophication Water Science and Technology |
| Zdroj: | Water and Environment Journal. 26:324-334 |
| ISSN: | 1747-6585 |
| DOI: | 10.1111/j.1747-6593.2011.00292.x |
| Popis: | Establishing nutrient reference condition (baseline environmental condition) of lakes in ecoregion is a critical consideration in the development of scientifically defensible aquatic nutrient criteria. Three methods were applied to determine reference conditions in Yungui Plateau ecoregion lakes with respect to total phosphorus, total nitrogen, planktonic chlorophyll a (chl a) and Secchi depth. First, minimally developed lake/catchment units were identified based on existing geographical database and visual basin survey. Lakes in these catchments were considered minimally disturbed ‘reference lakes’. Second, the frequency distribution of all of the lake data presently available by each variable was plotted, and the lower 25th percentile was selected as the reference condition for each value. Third, median nutrient, chl a and Secchi depth values were determined for the best one-third of lakes and applied as indicators of reference condition. The result of model prediction and data from historical record were used to test three techniques for determining reference condition. Reference conditions, as determined by these three methods, broadly agreed for all parameters. Overall, the data suggest that multiple methods can be used to determine reference condition, and that in Yungui lakes, reference condition corresponds to oligotrophic–mesotrophic status. |
| Databáze: | OpenAIRE |
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