Cyanobacteria bloom variations and atmospheric variables, an environmental health contribution

Abstract Urbanization in river basins contributes to the anthropogenic eutrophication of their water bodies, leading to the proliferation of toxic algae such as cyanobacteria. There is a characteristic pattern of seasonality in algal blooms and cyanobacterial communities, although these algae may be present or even dominant for most of the year, causing practical problems associated with high cyanobacterial biomass and potential health threats. The increased concentration of toxins originating from these algae, cyanotoxins, in water-supply reservoirs puts the population at serious risk, since they are not removed by conventional treatment and filtration. This study analyzed possible associations between climate elements and cyanobacteria biomass in the Guarapiranga dam reservoir, located in the metropolitan region of São Paulo, Brazil. Meteorological variables were studied exclusively in relation to the cyanobacteria biomass, in order to perceive the influence of weather and climate in this complex system and to provide data for modeling future climate change scenarios. For this purpose, cyanobacteria count data were used for the period from 2010 to 2016, grouped by month, in addition to the atmospheric variables. The strongest correlation with the blooms was with Irradiation and Total Rainfall, explaining 30% of cases of the occurrence of cyanobacteria proliferation at the point of collection GU 101. Despite the notable influence of climatic seasonality on the algae blooms, this difference varies and is not homogeneous, depending on the location and the species studied.

摘要 流域内的城市化进程会导致水体发生人为富营养化，进而引发蓝藻等有毒藻类大量繁殖。蓝藻水华与蓝藻群落具有典型的季节分布特征，尽管此类藻类在一年中多数时段均可存在甚至占据优势，由此引发的高蓝藻生物量问题会带来实际运维困境，并构成潜在健康威胁。供水水库中由藻类产生的藻毒素（cyanotoxins）浓度升高，会对周边人群构成严重健康风险，因为常规的水处理与过滤工艺无法去除此类毒素。本研究针对位于巴西圣保罗大都会区的瓜皮兰加水库（Guarapiranga Dam Reservoir），分析了气候要素与蓝藻生物量之间的潜在关联。本研究仅聚焦气象变量与蓝藻生物量的关联关系，以期明晰天气与气候对该复杂水体系统的影响，并为未来气候变化情景的建模研究提供数据支撑。为此，研究采用了2010年至2016年间按月汇总的蓝藻计数数据，并结合大气变量开展分析。在GU 101采样点，与蓝藻水华关联度最强的气象因子为辐照度与总降雨量，二者可解释30%的蓝藻大量繁殖发生案例。尽管气候季节效应对蓝藻水华存在显著影响，但该影响程度存在差异且并非均质分布，具体取决于研究点位与所涉藻类物种。