MOE Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
MOE Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Sci Total Environ. 2022 Aug 25;836:155700. doi: 10.1016/j.scitotenv.2022.155700. Epub 2022 May 3.
Chlorophyll-a (Chl-a) has been employed as the "golden proxy" of algae biomass and algae cell densities in lake environments for many years. However, how reliable Chl-a is as algae proxy in lake environments needs further evaluation. Here, we take the eutrophic Lake Chaohu and 46 lakes and reservoirs across China as objects on temporal and spatial scales, respectively, to resolve this issue from the perspective of n-alkanes. Our results showed that Chl-a ranged from 10.5 to 735 μg∙L with a geometric mean of 92.4 μg∙L in Lake Chaohu. There were no statistically significant correlations between Chl-a and algae cell densities in all seasons (Pearson's correlation, p > 0.05), and also for macrophytes and terrestrial plants input (p > 0.05). It was related to the complex changes of environmental factors. By contrast, Chl-a ranged from 7.1 to 1608 μg∙L with a geometric mean of 125 μg∙L in nationwide lakes and reservoirs, and its occurrence was not only related to algae, but also associated with macrophytes and terrestrial plants (p < 0.05). In summary, Chl-a can be applied as an algae proxy, but its application is subject to certain restrictions. Besides, the multiple sources of Chl-a in lake environments may result in an overestimation of algae cell densities. Compared to Chl-a, biogenic n-heptadecane (bio C) could be regarded as a potential alternative. Hence, we compared the advantages and disadvantages of bio C and Chl-a in the aspects of specificity, accuracy, sensitivity and applicability. We found that for most scenarios, their limitations could be surmounted by each other, but failed in some scenarios. Accordingly, an ensemble proxy system may be used for more reliable representation of algae in lake environments.
叶绿素 a（Chl-a）多年来一直被用作湖泊环境中藻类生物量和藻类细胞密度的“黄金代理”。然而，Chl-a 作为湖泊环境中藻类代理的可靠性仍需要进一步评估。在这里，我们分别以富营养化的巢湖和中国 46 个湖泊水库为对象，从正构烷烃的角度来解决这个问题。我们的研究结果表明，巢湖的 Chl-a 浓度范围为 10.5 至 735μg·L-1，几何平均值为 92.4μg·L-1。在所有季节，Chl-a 与藻类细胞密度之间均无统计学显著相关性（皮尔逊相关，p＞0.05），与浮游藻类和陆地植物输入也无相关性（p＞0.05）。这与环境因素的复杂变化有关。相比之下，全国湖泊水库的 Chl-a 浓度范围为 7.1 至 1608μg·L-1，几何平均值为 125μg·L-1，其出现不仅与藻类有关，还与大型藻类和陆地植物有关（p＜0.05）。总之，Chl-a 可以作为藻类的代理，但应用受到一定限制。此外，湖泊环境中 Chl-a 的多种来源可能导致藻类细胞密度的高估。与 Chl-a 相比，生物源正十七烷（bio C）可以被认为是一种潜在的替代物。因此，我们比较了 bio C 和 Chl-a 在特异性、准确性、灵敏度和适用性方面的优缺点。我们发现，在大多数情况下，它们的局限性可以相互克服，但在某些情况下无法克服。因此，可能需要使用集合代理系统来更可靠地表示湖泊环境中的藻类。
