Preliminary Investigation of Bioaccumulation of Microcystins in Hypereutrophic Irrigation Ponds Case Study-the Jordan Valley

Microcystis blooms , the related toxin known as microcystin-LR (MC-LR) put the safety of human water consumption and global irrigation practices in jeopardy. MC-LR is widely distributed in various environments, including water, sediments, plants , other aquatic organisms. The use of water-containing microcystins for ag-ricultural purposes may have to be restricted despite the limited availability of clean water resources. Accordingly, the present work aimed to determine the MC-LR concentrations and recognize the environmental parameters that initiate the growth of toxic cyanobacteria and MC-LR occurrence in 20 irrigation ponds in the Jordan Valley area. The irrigation ponds studied were found in a hypereutrophic condition, with high levels of N:P ratio and low trans-parency. These cause inseparable effects such as cyanobacterial bloom and MC-LR occurrence. The investigated ponds were classified as hypereutrophic according to General Quality Index (GQI), with two different types of algae covering the surface. The first was the Lemna sp. or duckweeds (Family Araceae) which are free-floating masses, and the second was the cyanobacteria algal bloom. Unpaired t-tests were performed and showed that the concentrations of MC-LR in pond water abundant with cyanobacteria algal bloom in September 2021 were signifi-cantly higher (P = 0.7906) than in June for the same year (0.3022 +/- 0.0444 and 0.1048 +/- 0.0171 ppb, respectively). Two methods for extracting MC-LR were used and showed a significant difference in MC-LR concentration in ponds with an abundance of cyanobacteria algal blooms (0.2273 +/- 0.0356 ppb) compared to the ponds with an abundance of Lemna sp. or duckweeds collected in June 2021 (0.1048 +/- 0.0171 ppb). Despite all of the efforts made by Jordan Valley farmers to prevent or limit the mass growth of cyanobacteria and its consequences for the eutrophication process in their irrigation ponds through the use of fish breading and chemicals such as copper sulfate, this environmental problem is still harming their crops and irrigation methods and requires immediate government assistance.