First Detection of Microcystin-LR in the Amazon River at the Drinking Water Treatment Plant of the Municipality of Macapá, Brazil

Abstract

Human poisoning by microcystin has been recorded in many countries, including Brazil, where fatal cases have already occurred. The Amazon River is the main source of drinking water in municipalities such as Macapá, where there is no monitoring of cyanobacteria and cyanotoxins. This study investigated the presence of cyanobacteria and cyanotoxins in samples from a drinking water treatment plant (DWTP) that catches water from the Amazon River. The toxin analyses employed ELISA, LC/MS, and molecular screening for genes involved in the production of cyanotoxins. The sampling was carried out monthly from April 2015 to April 2016 at the intake (raw water) and exit (treated water) of the DWTP. This study reports the first detection of microcystin-LR (MC-LR) in the Amazon River, the world’s largest river, and in its treated water destined for drinking water purposes in Macapá, Brazil. The cyanobacterial density and MC-LR concentration were both low during the year. However, Limnothrix planctonica showed a density peak (± 900 cells mL−1) in the quarter of June–August 2015, when MC-LR was registered (2.1 µg L−1). Statistical analyses indicate that L. planctonica may produce the microcystin.

Hydrodynamic Modeling and Simulation of Water Residence Time in the Estuary of the Lower Amazon River

“…In other words, the longer the water remains in the control volume, the greater the likelihood of passive flow agents remaining in the body of water. However, depending on the passive agent in the flow, this characteristic can be positive, for example, nutrients to feed the aquatic biota, or negative, to disperse pollutants [18,22,23,35,[43][44][45].…”

“…Despite the experimental and numerical barriers found in the present research, it is essential taking the first step towards assessing how Rt influences biogeochemical processes dependent on its own interactions in tropical aquatic ecosystems. In this case, it is essential understanding Rt's variations in space and time based on the complex characteristics of these channels [20][21][22][23]35].…”

“…The dynamics of these aquatic ecosystems is often influenced by the biogeochemical processes and nutrient cycles in HZs. These aquatic ecosystems depend on diffusive and dispersive processes associated with local hydrodynamics [32][33][34][35].…”

“…The value of the constituents was imposed in the nodes of the open boundary using adjustment of coefficients (in amplitude and phase) for each harmonic constituent. A similar methodology was used in [35,63,64].…”

Aberrant Expressional Profiling of Known MicroRNAs in the Liver of Silver Carp (Hypophthalmichthys molitrix) Following Microcystin-LR Exposure Based on samllRNA Sequencing

“…Cyanobacteria are highly adaptable and widely distributed photosynthetic bacteria in almost all environments [1]. In the past several decades, global warming and overinvestment in nutrients have both led to the frequency and intensity of large algal blooms [2].…”