Evaluation of cyanobacterial blooms in water supply rivers from Joinville city

ABSTRACT The proliferation of cyanobacteria in waters, especially in rivers, is associated with anthropic action, wastewater from industries, agriculture, and the lack of basic sanitation. Many health problems occur due to the cyanotoxins produced by these microorganisms. The present study aimed to evaluate the densities of cyanobacteria and their possible correlations with physical-chemical parameters in waters from supply rivers of the city of Joinville, in order to verify which factors are involved in the growth of these organisms between the years 2015 to 2019. The amount of cyanobacteria cells per milliliter of water were analyzed from the last 5 years of the Cubatão and Piraí rivers, based on the certificates of analysis provided by the current water supply service of Joinville. It was found that the cyanobacteria density values increased in both rivers from the year 2018. The physical-chemical parameters analyzed showed a low correlation with the cyanobacteria density from 2015 to 2019 for the Cubatão and Piraí rivers. To understand this increase in cyanobacteria, other climatic factors such as precipitation and average annual temperature were studied. The expressive increase in precipitation in January 2018, followed by a period of reduced rainfall, in addition to the gradual rising temperature in recent years, might be related to this elevation in the density of cyanobacteria between 2018 and 2019, requiring monitoring of this evolution in the supply rivers of the Joinville city.

摘要：水体（尤其是河流）中蓝藻（Cyanobacteria）的大量繁殖与人类活动、工农业废水以及基础卫生设施的缺失密切相关。此类微生物产生的蓝藻毒素可引发多种健康问题。本研究旨在评估若因维利市供水河流中的蓝藻密度，并探究其与水体理化参数间的潜在关联，以明确2015年至2019年间驱动该类微生物增殖的相关因素。本研究基于若因维利市当前供水服务机构出具的分析报告，对库巴唐河与皮赖河近5年每毫升水体中的蓝藻细胞密度进行了分析。结果显示，2018年起两条河流的蓝藻密度均出现上升。2015至2019年间，库巴唐河与皮赖河的蓝藻密度与所分析的理化参数之间相关性较低。为探明蓝藻密度上升的原因，本研究进一步考察了降水、年平均气温等其他气候因素。2018年1月降水量的显著跃升，叠加随后一段时期的降雨偏少，再叠加近年来气温的逐步升高，或与2018至2019年间蓝藻密度的上升存在关联，因此需对若因维利市供水河流的这一变化趋势开展持续监测。