Zabaleta Bernardo, Aubriot Luis, Olano Hernán, Achkar Marcel
Laboratorio de Desarrollo Sustentable y Gestión Ambiental del Territorio, Instituto de Ecología Y Ciencias Ambientales, Facultad de Ciencias, Universidad de La República, Montevideo, Uruguay.
Grupo de Ecología Y Fisiología de Fitoplancton, Sección Limnología, Instituto de Ecología Y Ciencias Ambientales, Facultad de Ciencias, Universidad de La República, Montevideo, Uruguay.
Environ Sci Pollut Res Int. 2023 Mar;30(15):43604-43618. doi: 10.1007/s11356-023-25334-9. Epub 2023 Jan 20.
Intensive agricultural activities favor eutrophication and harmful phytoplankton blooms due to the high export of nutrients and damming of rivers. Productive watersheds used for water purification can have multiple reservoirs with phytoplankton blooms, which constitutes a high health risk. In general, water quality monitoring does not cover small- and medium-sized reservoirs (0.25-100 ha) of productive use due to their large number and location in private properties. In this work, the in situ trophic state of fourteen reservoirs was simultaneously assessed using Sentinel-2 images in the Santa Lucía River Basin, the main drinking water basin in Uruguay. These reservoirs are hypereutrophic (0.18-5.22 mg total P L) with high phytoplankton biomasses (2.8-4439 µg chlorophyll-a L), mainly cyanobacteria. Based on data generated in situ and Sentinel-2 imagery, models were fitted to estimate satellite Chl-a and transparency in all the basin reservoirs (n = 486). The best fits were obtained with the green-to-red band ratio (560 and 665 nm, R = 0.84) to estimate chlorophyll-a and reflectance at 833 nm (R = 0.73) to determine transparency. The spatial distribution of the trophic state was explored by spatial autocorrelation and hotspot analysis, and the variation in spatial patterns could be determined prior and subsequent to a maximum cyanobacteria value in water treatment plant intakes. Therefore, reservoirs with greater potential for phytoplankton biomass export were identified. This work provides the first fitted tool for satellite monitoring of numerous reservoirs and strengthens the country's ability to respond to harmful phytoplankton blooms in its main drinking water basin.
集约化农业活动因养分大量输出和河流筑坝而有利于富营养化和有害浮游植物大量繁殖。用于水净化的高产流域可能有多个出现浮游植物大量繁殖的水库，这构成了很高的健康风险。一般来说，水质监测并未涵盖用于生产的中小型水库（面积0.25 - 100公顷），因为其数量众多且位于私人土地上。在这项研究中，利用哨兵 - 2号卫星图像同时评估了乌拉圭主要饮用水源地圣卢西亚河流域14个水库的原位营养状态。这些水库处于超富营养状态（总磷含量为0.18 - 5.22毫克/升），浮游植物生物量很高（叶绿素a含量为2.8 - 4439微克/升），主要是蓝藻。基于原位生成的数据和哨兵 - 2号卫星图像，建立了模型来估算该流域所有水库（n = 486）的卫星叶绿素a含量和透明度。利用绿红波段比值（560和665纳米，R = 0.84）估算叶绿素a，利用833纳米处的反射率（R = 0.73）确定透明度时，拟合效果最佳。通过空间自相关和热点分析探索了营养状态的空间分布，并确定了水处理厂取水口处蓝藻最大值出现之前和之后空间格局的变化。因此，确定了浮游植物生物量输出潜力较大的水库。这项工作为众多水库的卫星监测提供了首个拟合工具，并增强了该国应对其主要饮用水源地有害浮游植物大量繁殖的能力。
